WorldWideScience

Sample records for calcium base alloys

  1. Stress-Relaxation Behavior of Magnesium-3Gadolinium-2Calcium-Based Alloys at Elevated Temperatures

    Science.gov (United States)

    Mo, Ning; Tan, Qiyang; Jiang, Bin; Pan, Fusheng; Zhang, Ming-Xing

    2017-11-01

    Based on previously published work on binary Mg alloys by Abaspour et al. and on the magnesium (Mg)-6gadolinium (Gd)-2zinc (Zn)-0.6zirconium (Zr) (wt pct) alloy reported by Nie et al., a number of new lower-cost Mg-3Gd-2calcium (Ca) (wt pct)-based creep-resistant magnesium alloys were developed by replacing part of the Gd with Ca. After solution treatment at 793 K (520 °C), the Ca-containing alloys exhibited an increased strength and a reduced stress relaxation at 453 K (180 °C) compared with the Mg-6Gd-2Zn-0.6Zr (wt pct) alloy. This work indicates that the replacement of Gd with Ca is a promising approach to develop lower-cost Mg alloys with an improved creep resistance. The results support the hypothesis that the short-range order of solutes governs the creep behavior of magnesium alloys.

  2. CaO insulator coatings on a vanadium-base alloy in liquid 2 at.% calcium-lithium

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.H.; Kassner, T.F. [Argonne National Laboratory, IL (United States)

    1996-10-01

    The electrical resistance of CaO coatings produced on V-4%Cr-4%Ti and V-15%Cr-5%Ti by exposure of the alloy (round bottom samples 6-in. long by 0.25-in. dia.) to liquid lithium that contained 2 at.% dissolved calcium was measured as a function of time at temperatures between 300-464{degrees}C. The solute element, calcium in liquid lithium, reacted with the alloy substrate at these temperatures for 17 h to produce a calcium coating {approx}7-8 {mu}m thick. The calcium-coated vanadium alloy was oxidized to form a CaO coating. Resistance of the coating layer on V-15Cr-5Ti, measured in-situ in liquid lithium that contained 2 at.% calcium, was 1.0 x 10{sup 10} {Omega}-cm{sup 2} at 300{degrees}C and 400 h, and 0.9 x 10{sup 10} {Omega}-cm{sup 2} at 464{degrees}C and 300 h. Thermal cycling between 300 and 464{degrees}C changed the resistance of the coating layer, which followed insulator behavior. Examination of the specimen after cooling to room temperature revealed no cracks in the CaO coating. The coatings were evaluated by optical microscopy, scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), and X-ray analysis. Adhesion between CaO and vanadium alloys was enhanced as exposure time increased.

  3. Corrosion Behavior of PEO Coatings Formed on AZ31 Alloy in Phosphate-Based Electrolytes with Calcium Acetate Additive

    Science.gov (United States)

    Ziyaei, E.; Atapour, M.; Edris, H.; Hakimizad, A.

    2017-07-01

    The PEO coating started on magnesium AZ31 using a unipolar DC power source. The coating was generated in the electrolyte based on Na3PO4·12H2O and KOH with calcium acetate as additive. The x-ray diffraction method showed some phases containing calcium and phosphate, which was created in the presence of additive. Also, the EDS tests of the sample's surfaces proved the existence of calcium on the surface. Based on the electrochemical tests results, the most corrosion resistance belongs to the sample with calcium acetate additive. In fact, the results of the EIS tests showed the coating with calcium acetate has the highest resistance but the lowest capacitance. However, this state belongs to the surface morphology, the lower porosity, and surface chemical composition.

  4. Calcium orthophosphate coatings on magnesium and its biodegradable alloys.

    Science.gov (United States)

    Dorozhkin, Sergey V

    2014-07-01

    Biodegradable metals have been suggested as revolutionary biomaterials for bone-grafting therapies. Of these metals, magnesium (Mg) and its biodegradable alloys appear to be particularly attractive candidates due to their non-toxicity and as their mechanical properties match those of bones better than other metals do. Being light, biocompatible and biodegradable, Mg-based metallic implants have several advantages over other implantable metals currently in use, such as eliminating both the effects of stress shielding and the requirement of a second surgery for implant removal. Unfortunately, the fast degradation rates of Mg and its biodegradable alloys in the aggressive physiological environment impose limitations on their clinical applications. This necessitates development of implants with controlled degradation rates to match the kinetics of bone healing. Application of protective but biocompatible and biodegradable coatings able to delay the onset of Mg corrosion appears to be a reasonable solution. Since calcium orthophosphates are well tolerated by living organisms, they appear to be the excellent candidates for such coatings. Nevertheless, both the high chemical reactivity and the low melting point of Mg require specific parameters for successful deposition of calcium orthophosphate coatings. This review provides an overview of current coating techniques used for deposition of calcium orthophosphates on Mg and its biodegradable alloys. The literature analysis revealed that in all cases the calcium orthophosphate protective coatings both increased the corrosion resistance of Mg-based metallic biomaterials and improved their surface biocompatibility. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  5. Biodegradable Orthopedic Magnesium-Calcium (MgCa Alloys, Processing, and Corrosion Performance

    Directory of Open Access Journals (Sweden)

    Yuebin Guo

    2012-01-01

    Full Text Available Magnesium-Calcium (Mg-Ca alloy has received considerable attention as an emerging biodegradable implant material in orthopedic fixation applications. The biodegradable Mg-Ca alloys avoid stress shielding and secondary surgery inherent with permanent metallic implant materials. They also provide sufficient mechanical strength in load carrying applications as opposed to biopolymers. However, the key issue facing a biodegradable Mg-Ca implant is the fast corrosion in the human body environment. The ability to adjust degradation rate of Mg-Ca alloys is critical for the successful development of biodegradable orthopedic implants. This paper focuses on the functions and requirements of bone implants and critical issues of current implant biomaterials. Microstructures and mechanical properties of Mg-Ca alloys, and the unique properties of novel magnesium-calcium implant materials have been reviewed. Various manufacturing techniques to process Mg-Ca based alloys have been analyzed regarding their impacts on implant performance. Corrosion performance of Mg-Ca alloys processed by different manufacturing techniques was compared. In addition, the societal and economical impacts of developing biodegradable orthopedic implants have been emphasized.

  6. Shape memory alloy based motor

    Indian Academy of Sciences (India)

    http://www.ias.ac.in/article/fulltext/sadh/033/05/0699-0712. Keywords. Shape Memory Alloy (SMA); poly phase; rotary actuator; torque; ripple. Abstract. Design and characterization of a new shape memory alloy wire based Poly Phase Motor has been reported in this paper. The motor can be used either in stepping mode or ...

  7. Studying microstructure and phase composition of a new complex calcium containing alloy

    Directory of Open Access Journals (Sweden)

    I. Bartenev

    2016-10-01

    Full Text Available In the given article there are presented the results of studying the microstructure and phase structure of a complex alloy of alumosilicon with calcium. It is established that in the studied CAMS alloy active elements are present at a type of difficult intermetallid that positively influences quality of both ordinary, and qualitative brands of steel.

  8. Biomimetic coprecipitation of calcium phosphate and bovine serum albumin on titanium alloy

    NARCIS (Netherlands)

    Liu, Yuelian; Layrolle, Pierre; de Bruijn, Joost Dick; van Blitterswijk, Clemens; de Groot, K.

    2001-01-01

    Titanium alloy implants were precoated biomimetically with a thin and dense layer of calcium phosphate and then incubated either in a supersaturated solution of calcium phosphate or in phosphate-buffered saline, each containing bovine serum albumin (BSA) at various concentrations, under

  9. Repassivation Potential of Alloy 22 in Sodium and Calcium Chloride Brines

    Energy Technology Data Exchange (ETDEWEB)

    Rebak, R B; Ilevbare, G O; Carranza, R M

    2007-08-11

    A comprehensive matrix of 60 tests was designed to explore the effect of calcium chloride vs. sodium chloride and the ratio R of nitrate concentration over chloride concentration on the repassivation potential of Alloy 22. Tests were conducted using the cyclic potentiodynamic polarization (CPP) technique at 75 C and at 90 C. Results show that at a ratio R of 0.18 and higher nitrate was able to inhibit the crevice corrosion in Alloy 22 induced by chloride. Current results fail to show in a consistent way a different effect on the repassivation potential of Alloy 22 for calcium chloride solutions than for sodium chloride solutions.

  10. Wettability of magnesium based alloys

    Science.gov (United States)

    Ornelas, Victor Manuel

    The premise of this project was to determine the wettability behavior of Mg-based alloys using three different liquids. Contact angle measurements were carried out along with utilizing the Zisman method for obtaining values for the critical surface tension. Adhesion energy values were also found through the use of the Young-Dupre equation. This project utilized the Mg-based alloy Mg-2Zn-2Gd with supplemented alpha-Minimum Essential Medium (MEM), Phosphate Buffer Saline solution (PBS), and distilled water. These three liquids are commonly used in cell cultivation and protein adsorption studies. Supplemented alpha-MEM consisted of alpha-MEM, fetal bovine serum, and penicillin-streptomycin. Mg-2Zn-2Gd was used because of observed superior mechanical properties and better corrosion resistance as compared to conventional Mg-alloys. These attractive properties have made it possible for this alloy to be used in biomedical devices within the human body. However, the successful use of this alloy system in the human body requires knowledge in the response of protein adsorption on the alloy surface. Protein adsorption depends on many parameters, but one of the most important factors is the wettability behavior at the surface.

  11. Calcium Orthophosphate-Based Bioceramics

    Directory of Open Access Journals (Sweden)

    Sergey V. Dorozhkin

    2013-09-01

    Full Text Available Various types of grafts have been traditionally used to restore damaged bones. In the late 1960s, a strong interest was raised in studying ceramics as potential bone grafts due to their biomechanical properties. A bit later, such synthetic biomaterials were called bioceramics. In principle, bioceramics can be prepared from diverse materials but this review is limited to calcium orthophosphate-based formulations only, which possess the specific advantages due to the chemical similarity to mammalian bones and teeth. During the past 40 years, there have been a number of important achievements in this field. Namely, after the initial development of bioceramics that was just tolerated in the physiological environment, an emphasis was shifted towards the formulations able to form direct chemical bonds with the adjacent bones. Afterwards, by the structural and compositional controls, it became possible to choose whether the calcium orthophosphate-based implants remain biologically stable once incorporated into the skeletal structure or whether they were resorbed over time. At the turn of the millennium, a new concept of regenerative bioceramics was developed and such formulations became an integrated part of the tissue engineering approach. Now calcium orthophosphate scaffolds are designed to induce bone formation and vascularization. These scaffolds are often porous and harbor different biomolecules and/or cells. Therefore, current biomedical applications of calcium orthophosphate bioceramics include bone augmentations, artificial bone grafts, maxillofacial reconstruction, spinal fusion, periodontal disease repairs and bone fillers after tumor surgery. Perspective future applications comprise drug delivery and tissue engineering purposes because calcium orthophosphates appear to be promising carriers of growth factors, bioactive peptides and various types of cells.

  12. First-principles studies on alloying and simplified thermodynamic aqueous chemical stability of calcium-, zinc-, aluminum-, yttrium- and iron-doped magnesium alloys.

    Science.gov (United States)

    Velikokhatnyi, Oleg I; Kumta, Prashant N

    2010-05-01

    In the present study, the density functional theory implemented in the Vienna Ab-initio Simulation Package has been used to investigate the alloying effects of different elements of calcium, zinc, yttrium, aluminum and iron when introduced in the Mg crystal lattice. In particular, studies have been conducted to investigate the thermodynamics of the overall hydrolysis reaction of the different alloys with pure water. Phase stability results obtained from the first-principles calculations of the alloys considered are in good agreement with the published phase diagrams. The heats of the aqueous chemical reactions calculated in this study have been compared with that corresponding to the reaction of pure Mg with water. The heats of reactions dependence on the chemical compositions of the alloys have been investigated and, specifically, the role of Ca, Zn, Y, Al and Fe on the aqueous chemical stability and reactivity of these Mg alloys have been discussed. Results of these studies will help understand the biodegradable characteristic of Mg based alloys. Copyright (c) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  13. High strength forgeable tantalum base alloy

    Science.gov (United States)

    Buckman, R. W., Jr.

    1975-01-01

    Increasing tungsten content of tantalum base alloy to 12-15% level will improve high temperature creep properties of existing tantalum base alloys while retaining their excellent fabrication and welding characteristics.

  14. Rapid coating of AZ31 magnesium alloy with calcium deficient hydroxyapatite using microwave energy

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Yufu, E-mail: Yufu.Ren@rockets.utoledo.edu [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Zhou, Huan [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu (China); Nabiyouni, Maryam [Department of Bioengineering, The University of Toledo, Toledo, OH (United States); Bhaduri, Sarit B. [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Division of Dentistry, The University of Toledo, Toledo, OH (United States)

    2015-04-01

    Due to their unique biodegradability, magnesium alloys have been recognized as suitable metallic implant materials for degradable bone implants and bioresorbable cardiovascular stents. However, the extremely high degradation rate of magnesium alloys in physiological environment has restricted its practical application. This paper reports the use of a novel microwave assisted coating technology to improve the in vitro corrosion resistance and biocompatibility of Mg alloy AZ31. Results indicate that a dense calcium deficient hydroxyapatite (CDHA) layer was uniformly coated on a AZ31 substrate in less than 10 min. Weight loss measurement and SEM were used to evaluate corrosion behaviors in vitro of coated samples and of non-coated samples. It was seen that CDHA coatings remarkably reduced the mass loss of AZ31 alloy after 7 days of immersion in SBF. In addition, the prompt precipitation of bone-like apatite layer on the sample surface during immersion demonstrated a good bioactivity of the CDHA coatings. Proliferation of osteoblast cells was promoted in 5 days of incubation, which indicated that the CDHA coatings could improve the cytocompatibility of the AZ31 alloy. All the results suggest that the CDHA coatings, serving as a protective layer, can enhance the corrosion resistance and biological response of magnesium alloys. Furthermore, this microwave assisted coating technology could be a promising method for rapid surface modification of biomedical materials. - Highlights: • A microwave assisted coating process for biodegradable Mg alloy. • CDHA coatings were successfully developed on AZ31 alloy in minutes. • The as-deposited CDHA coatings significantly reduced the degradation rate of AZ31 alloy. • The CDHA coated AZ31 alloy showed good bioactivity and biocompatibility in vitro. • The microwave assisted coating process can be used as rapid surface modification for bioimplants.

  15. Hall effect in amorphous calcium-aluminum alloys

    Science.gov (United States)

    Mayeya, F. M.; Howson, M. A.

    1994-02-01

    We present results of the Hall effect measurements in CaAl(Au) amorphous alloys. The Hall coefficients have been found to be negative and independent of temperature. Their magnitudes deviate significantly from the nearly-free-electron calculations, and are reduced by gold doping. These deviations have been accounted for from considerations of the unusual electronic structure of CaAl, and the effects of both s-d hybridization and side-jump mechanism on the conduction electrons.

  16. Bulk amorphous Mg-based alloys

    DEFF Research Database (Denmark)

    Pryds, Nini

    2004-01-01

    and a low glass transition temperature. The alloys were prepared by using a relatively simple technique, i.e. rapid cooling of the melt in a copper wedge mould. The essential structural changes that are achieved by going from the amorphous to the crystalline state through the supercooled liquid state...... are discussed in this paper. On the basis of these measurements phase diagrams of the different systems were constructed. Finally, it is demonstrated that when pressing the bulk amorphous alloy onto a metallic dies at temperatures within the supercooled liquid region, the alloy faithfully replicates the surface......The present paper describes the preparation and properties of bulk amorphous quarternary Mg-based alloys and the influence of additional elements on the ability of the alloy to form bulk amorphous. The main goal is to find a Mg-based alloy system which shows both high strength to weight ratio...

  17. A novel biodegradable nicotinic acid/calcium phosphate composite coating on Mg-3Zn alloy

    Energy Technology Data Exchange (ETDEWEB)

    Song, Yingwei, E-mail: ywsong@imr.ac.cn; Shan, Dayong; Han, En-Hou

    2013-01-01

    A novel biodegradable composite coating is prepared to reduce the biodegradation rate of Mg-3Zn alloy. The Mg-3Zn substrate is first immersed into 0.02 mol L{sup -1} nicotinic acid (NA) solution, named as vitamin B{sub 3}, to obtain a pretreatment film, and then the electrodeposition of calcium phosphate coating with ultrasonic agitation is carried out on the NA pretreatment film to obtain a NA/calcium phosphate composite coating. Surface morphology is observed by scanning electron microscopy (SEM). Chemical composition is determined by X-ray diffraction (XRD) and EDX. Protection property of the coatings is evaluated by electrochemical tests. The biodegradable behavior is investigated by immersion tests. The results indicate that a thin but compact bottom layer can be obtained by NA pretreatment. The electrodeposition calcium phosphate coating consists of many flake particles and ultrasonic agitation can greatly improve the compactness of the coating. The composite coating is biodegradable and can reduce the biodegradation rate of Mg alloys in stimulated body fluid (SBF) for twenty times. The biodegradation process of the composite coating can be attributed to the gradual dissolution of the flake particles into chippings. - Highlights: Black-Right-Pointing-Pointer NA/calcium phosphate composite coating is prepared to protect Mg-3Zn alloy implant. Black-Right-Pointing-Pointer Nicotinic acid (vitamin B{sub 3}) is available to obtain a protective bottom film. Black-Right-Pointing-Pointer Ultrasonic agitation greatly improves the compactness of calcium phosphate coating. Black-Right-Pointing-Pointer The composite coating can reduce the biodegradation rate of Mg-3Zn twenty times. Black-Right-Pointing-Pointer The composite coating is biodegraded by the dissolution of flakes into chippings.

  18. Calcium-based multi-element chemistry for grid-scale electrochemical energy storage

    Science.gov (United States)

    Ouchi, Takanari; Kim, Hojong; Spatocco, Brian L.; Sadoway, Donald R.

    2016-03-01

    Calcium is an attractive material for the negative electrode in a rechargeable battery due to its low electronegativity (high cell voltage), double valence, earth abundance and low cost; however, the use of calcium has historically eluded researchers due to its high melting temperature, high reactivity and unfavorably high solubility in molten salts. Here we demonstrate a long-cycle-life calcium-metal-based rechargeable battery for grid-scale energy storage. By deploying a multi-cation binary electrolyte in concert with an alloyed negative electrode, calcium solubility in the electrolyte is suppressed and operating temperature is reduced. These chemical mitigation strategies also engage another element in energy storage reactions resulting in a multi-element battery. These initial results demonstrate how the synergistic effects of deploying multiple chemical mitigation strategies coupled with the relaxation of the requirement of a single itinerant ion can unlock calcium-based chemistries and produce a battery with enhanced performance.

  19. Development of Lightweight Titanium Base Alloys

    Science.gov (United States)

    1989-04-15

    as base alloy compositions. After the program began, the gamma-Ti-35A1 alloy was added. The principal thrust was to add significant amounts of Be to...creepresistance at high temperatures. A secondary thrust of this program was to add Li arid Mg to the base alloys in sufficient concentrations to decrease overall...selected al!oy samples were determined by using the Archimedes technique with water at 23°C; these densities are compared with densities of tne

  20. RGDC Peptide-Induced Biomimetic Calcium Phosphate Coating Formed on AZ31 Magnesium Alloy

    Science.gov (United States)

    Cao, Lin; Wang, Lina; Fan, Lingying; Xiao, Wenjun; Lin, Bingpeng; Xu, Yimeng; Liang, Jun; Cao, Baocheng

    2017-01-01

    Magnesium alloys as biodegradable metal implants have received a lot of interest in biomedical applications. However, magnesium alloys have extremely high corrosion rates a in physiological environment, which have limited their application in the orthopedic field. In this study, calcium phosphate compounds (Ca–P) coating was prepared by arginine–glycine–aspartic acid–cysteine (RGDC) peptide-induced mineralization in 1.5 simulated body fluid (SBF) to improve the corrosion resistance and biocompatibility of the AZ31 magnesium alloys. The adhesion of Ca–P coating to the AZ31 substrates was evaluated by a scratch test. Corrosion resistance and cytocompatibility of the Ca–P coating were investigated. The results showed that the RGDC could effectively promote the nucleation and crystallization of the Ca–P coating and the Ca–P coating had poor adhesion to the AZ31 substrates. The corrosion resistance and biocompatibility of the biomimetic Ca–P coating Mg alloys were greatly improved compared with that of the uncoated sample. PMID:28772717

  1. Nickel-base alloys for severe environments

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, R.K.; Flower, H.L. [Inco Alloys International Inc., Huntington, WV (United States); Hack, G.A.J. [Inco Alloys Ltd., Hereford (United Kingdom); Isobe, S. [Daido Steel Co. Ltd., Nagoya (Japan)

    1996-03-01

    Inconel alloys MA754 and MA758 are nickel-base, oxide dispersion-strengthened superalloys made by mechanical alloying. The simple nickel-chromium matrix, when combined with the strengthening effect of the yttrium oxide dispersoid during mechanical alloys, provides excellent creep properties, resistance to thermal fatigue, and surface stability suitable for operation without protective coatings. Gas turbine engine components are primary applications for alloy MA754, but this aerospace alloy has been applied in many other products that operate in severe conditions, and alloy MA758 was developed specifically for aggressive, elevated temperature industrial environments. Billets for large bar and plate are typically consolidated by hot isostatic pressing (HIP), because this technology allows production of forms suitable for a variety of industrial components. Material consolidated by HIP and conventionally worked by extrusion and hot rolling generally exhibits properties that are more isotropic than those of material consolidated by extrusion. However, the degree of anisotropy depends strongly on the specific processing of the consolidated billet. This article describes production of new mill shapes from HIP billets, and reviews current and potential applications such as skid rails for high-temperature walking-beam furnaces, heat treating furnace parts, equipment for handling molten glass, and furnace tubes.

  2. [Superplastic forming of titanium alloy denture base].

    Science.gov (United States)

    Okuno, O; Nakano, T; Hamanaka, H; Miura, I; Ito, M; Ai, M; Okada, M

    1989-03-01

    Ti-6Al-4V alloy has both excellent biocompatibility and superior mechanical properties. This Ti-6Al-4V can be deformed greatly and easily at the superplastic temperature of 800 degrees C to 900 degrees C. The superplastic forming of Ti-6Al-4V was made to apply to fabrication of denture base. Almost the same procedure as for dental casting mold was employed in producing the superplastic forming die by the improved phosphate bonded investment. In the pressure vessel of heat resistant alloy, Ti-6Al-4V plate was formed superplastically on the die by argon gas pressure at 850 degrees C. The fit of superplactic forming Ti-6Al-4V denture base was better than that of casting Co-Cr alloy denture bases. The Ti-6Al-4V alloy might react a little with the die. Because micro Vikers hardness of the cross-section did not go up too much near the surfaces. Even just after being formed, the surfaces were much smoother than that of Co-Cr alloy casting. The tensile strength and yield strength of superplastic forming Ti-6Al-4V were higher than those of Co-Cr castings. The elongation was about 10%. These results show that superplastic forming of Ti-6Al-4V would be suitable for a denture base.

  3. Fabrication of Superhydrophobic Calcium Phosphate Coating on Mg-Zn-Ca alloy and Its Corrosion Resistance

    Science.gov (United States)

    Zhang, Lashuang; Jiang, Yue; Zai, Wei; Li, Guangyu; Liu, Shaocheng; Lian, Jianshe; Jiang, Zhonghao

    2017-11-01

    A novel superhydrophobic calcium phosphate coating was prepared on a magnesium alloy substrate by a highly effective chemical conversion process and subsequent chemical modification. Different methods were employed to characterize the surface morphology and chemical composition as well as measure the wettability of the coating. It was demonstrated that the as-prepared superhydrophobic calcium phosphate coating has a typical three-level hierarchical structure consisted of micro-protrusions, submicro-lumps and nano-grains, conferring excellent superhydrophobicity with a water contact angle of 159°. The electrochemical measurements and appropriate equivalent circuit revealed that the corrosion-resistant performance of the superhydrophobic calcium phosphate coating was significantly improved as compared with that of the substrate, the corrosion potential of the superhydrophobic coating increases from -1.56 to -1.36 V, and its corrosion current density decreases from 1.29 × 10-4 to 1.3 × 10-6 A/cm2. The anti-corrosion mechanism of the superhydrophobic coating was also discussed. It can be indicated that the corrosion inhibitive properties of the coating are in accordance with its hydrophobicity, which is owing to the presence of a protective layer of air trapped in the grooves of the coating surface to isolate the underlying materials from the external environment.

  4. Study of calcium phosphate (DCPD electrodeposition process on a Mg-3Al-1Zn magnesium alloy surface

    Directory of Open Access Journals (Sweden)

    Filip Pastorek

    2013-02-01

    Full Text Available Evaluation of calcium phosphating process realized on Mg-3Al-1Zn alloy surface after grinding was investigated by electrochemical tests supported by photodocumentation. The electrodeposition treatment was performed by electrochemical method in water solution of Ca(NO32.4H2O, (NH42HPO4 and H2O2. The formation of calcium phosphate was divided into several stages and described using light microscopy. The progress in corrosion protection of created calcium phosphate layer in 0.9% NaCl after particular electrodeposition steps was evaluated by electrochemical impedance spectroscopy. The results in the form of Nyquist plots were analyzed using equivalent circuits.

  5. STUDY OF CALCIUM PHOSPHATE (DCPD ELECTRODEPOSITION PROCESS ON THE Mg-3Al-1Zn MAGNESIUM ALLOY SURFACE

    Directory of Open Access Journals (Sweden)

    Filip Pastorek

    2013-02-01

    Full Text Available Evaluation of calcium phosphating process realized on the Mg-3Al-1Zn alloy surface after grinding was investigated by electrochemical tests supported by photodocumentation. The electrodeposition treatment was performed by electrochemical method in water solution of Ca(NO32.4H2O, (NH42HPO4 and H2O2. The formation of calcium phosphate was divided into several stages and described using light microscopy. The progress in corrosion protection of created calcium phosphate layer in 0.9% NaCl after particular electrodeposition steps was evaluated by electrochemical impedance spectroscopy. The results in the form of Nyquist plots were analyzed using equivalent circuits.

  6. Rapid solidification of Nb-base alloys

    Science.gov (United States)

    Gokhale, A. B.; Javed, K. R.; Abbaschian, G. J.; Lewis, R. E.

    1988-01-01

    New Nb-base alloys are of interest for aerospace structural applications at high temperatures, viz, 800 to 1650 C. Fundamental information regarding the effects of rapid solidification in achieving greatly refined microstructures, extended solid solubility, suppression of embrittling equilibrium phases, and formation of new phases is desired in a number of Nb-X alloys. The microstructures and selected properties of Nb-Si and other Nb-base alloys are presented for materials both rapidly quenched from the equilibrium liquidus and rapidly solidified following deep supercooling. Electromagnetic levitation was used to achieve melting and supercooling in a containerless inert gas environment. A variety of solidification conditions were employed including splatting or drop casting of supercooled samples. The morphology and composition of phases formed are discussed in terms of both solidification history and bulk composition.

  7. Irradiation creep of vanadium-base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, H.; Billone, M.C.; Strain, R.V.; Smith, D.L. [Argonne National Lab., IL (United States); Matsui, H. [Tohoku Univ. (Japan)

    1998-03-01

    A study of irradiation creep in vanadium-base alloys is underway with experiments in the Advanced Test Reactor (ATR) and the High Flux Isotope Reactor (HFIR) in the United States. Test specimens are thin-wall sealed tubes with internal pressure loading. The results from the initial ATR irradiation at low temperature (200--300 C) to a neutron damage level of 4.7 dpa show creep rates ranging from {approx}0 to 1.2 {times} 10{sup {minus}5}/dpa/MPa for a 500-kg heat of V-4Cr-4Ti alloy. These rates were generally lower than reported from a previous experiment in BR-10. Because both the attained neutron damage levels and the creep strains were low in the present study, however, these creep rates should be regarded as only preliminary. Substantially more testing is required before a data base on irradiation creep of vanadium alloys can be developed and used with confidence.

  8. 21 CFR 872.3710 - Base metal alloy.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Base metal alloy. 872.3710 Section 872.3710 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3710 Base metal alloy. (a) Identification. A base metal alloy is a device composed primarily of base metals, such as nickel, chromium, or cobalt, that is...

  9. Discontinuous precipitation in copper base alloys

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Discontinuous precipitation (DP) is associated with grain boundary migration in the wake of which alternate plates of the precipitate and the depleted matrix form. Some copper base alloys show DP while others do not. In this paper the misfit strain parameter, η, has been calculated and predicted that if.

  10. Discontinuous precipitation in copper base alloys

    Indian Academy of Sciences (India)

    Discontinuous precipitation (DP) is associated with grain boundary migration in the wake of which alternate plates of the precipitate and the depleted matrix form. Some copper base alloys show DP while others do not. In this paper the misfit strain parameter, , has been calculated and predicted that if 100 > ± 0.1, DP is ...

  11. Blood compatibility of zinc-calcium phosphate conversion coating on Mg-1.33Li-0.6Ca alloy

    Science.gov (United States)

    Zou, Yu-Hong; Zeng, Rong-Chang; Wang, Qing-Zhao; Liu, Li-Jun; Xu, Qian-Qian; Wang, Chuang; Liu, Zhi-Wei

    2016-09-01

    Magnesium alloys as a new class of biomaterials possess biodegradability and biocompatibility in comparison with currently used metal implants. However, their rapid corrosion rates are necessary to be manipulated by appropriate coatings. In this paper, a new attempt was used to develop a zinc-calcium phosphate (Zn-Ca-P) conversion coating on Mg-1.33Li-0.6Ca alloys to increase the biocompatibility and improve the corrosion resistance. In vitro blood biocompatibility of the alloy with and without the Zn-Ca-P coating was investigated to determine its suitability as a degradable medical biomaterial. Blood biocompatibility was assessed from the hemolysis test, the dynamic cruor time test, blood cell count and SEM observation of the platelet adhesion to membrane surface. The results showed that the Zn-Ca-P coating on Mg-1.33Li-0.6Ca alloys had good blood compatibility, which is in accordance with the requirements for medical biomaterials.

  12. Lead and lead-based alloys as waste matrix materials

    Energy Technology Data Exchange (ETDEWEB)

    Arustamov, A.E.; Ojovan, M.I.; Kachalov, M.B.

    1999-07-01

    Metals and alloys with relatively low melting temperatures such as lead and lead-based alloys are considered in Russia as prospective matrices for encapsulation of spent nuclear fuel in containers in preparation for final disposal in underground repositories. Now lead and lead-based alloys are being used for conditioning spent sealed radioactive sources at radioactive waste disposal facilities.

  13. Vanadium-base alloys for fusion reactor applications

    Energy Technology Data Exchange (ETDEWEB)

    Smith, D.L.; Loomis, B.A.; Diercks, D.R.

    1984-10-01

    Vanadium-base alloys offer potentially significant advantages over other candidate alloys as a structural material for fusion reactor first wall/blanket applications. Although the data base is more limited than that for the other leading candidate structural materials, viz., austenitic and ferritic steels, vanadium-base alloys exhibit several properties that make them particularly attractive for the fusion reactor environment. This paper presents a review of the structural material requirements, a summary of the materials data base for selected vanadium-base alloys, and a comparison of projected performance characteristics compared to other candidate alloys. Also, critical research and development (R and D) needs are defined.

  14. Calcium

    Science.gov (United States)

    ... Turn to calcium-fortified (or "calcium-set") tofu, soy milk, tempeh, soy yogurt, and cooked soybeans (edamame). Calcium-fortified foods. Look for calcium-fortified orange juice, soy or rice milk, breads, and cereal. Beans. You can get decent ...

  15. Excessively High Vapor Pressure of Al-based Amorphous Alloys

    OpenAIRE

    Jeong, Jae; Lee, Sung; Jeon, Je-Beom; Kim, Suk

    2015-01-01

    Aluminum-based amorphous alloys exhibited an abnormally high vapor pressure at their approximate glass transition temperatures. The vapor pressure was confirmed by the formation of Al nanocrystallites from condensation, which was attributed to weight loss of the amorphous alloys. The amount of weight loss varied with the amorphous alloy compositions and was inversely proportional to their glass-forming ability. The vapor pressure of the amorphous alloys around 573 K was close to the va...

  16. New Developments of Ti-Based Alloys for Biomedical Applications.

    Science.gov (United States)

    Li, Yuhua; Yang, Chao; Zhao, Haidong; Qu, Shengguan; Li, Xiaoqiang; Li, Yuanyuan

    2014-03-04

    Ti-based alloys are finding ever-increasing applications in biomaterials due to their excellent mechanical, physical and biological performance. Nowdays, low modulus β-type Ti-based alloys are still being developed. Meanwhile, porous Ti-based alloys are being developed as an alternative orthopedic implant material, as they can provide good biological fixation through bone tissue ingrowth into the porous network. This paper focuses on recent developments of biomedical Ti-based alloys. It can be divided into four main sections. The first section focuses on the fundamental requirements titanium biomaterial should fulfill and its market and application prospects. This section is followed by discussing basic phases, alloying elements and mechanical properties of low modulus β-type Ti-based alloys. Thermal treatment, grain size, texture and properties in Ti-based alloys and their limitations are dicussed in the third section. Finally, the fourth section reviews the influence of microstructural configurations on mechanical properties of porous Ti-based alloys and all known methods for fabricating porous Ti-based alloys. This section also reviews prospects and challenges of porous Ti-based alloys, emphasizing their current status, future opportunities and obstacles for expanded applications. Overall, efforts have been made to reveal the latest scenario of bulk and porous Ti-based materials for biomedical applications.

  17. Electrochemical characteristics of calcium-phosphatized AZ31 magnesium alloy in 0.9 % NaCl solution.

    Science.gov (United States)

    Hadzima, Branislav; Mhaede, Mansour; Pastorek, Filip

    2014-05-01

    Magnesium alloys suffer from their high reactivity in common environments. Protective layers are widely created on the surface of magnesium alloys to improve their corrosion resistance. This article evaluates the influence of a calcium-phosphate layer on the electrochemical characteristics of AZ31 magnesium alloy in 0.9 % NaCl solution. The calcium phosphate (CaP) layer was electrochemically deposited in a solution containing 0.1 M Ca(NO3)2, 0.06 M NH4H2PO4 and 10 ml l(-1) of H2O2. The formed surface layer was composed mainly of brushite [(dicalcium phosphate dihidrate (DCPD)] as proved by energy-dispersive X-ray analysis. The surface morphology was observed by scanning electron microscopy. Immersion test was performed in order to observe degradation of the calcium phosphatized surfaces. The influence of the phosphate layer on the electrochemical characteristics of AZ31, in 0.9 % NaCl solution, was evaluated by potentiodynamic measurements and electrochemical impedance spectroscopy. The obtained results were analysed by the Tafel-extrapolation method and equivalent circuits method. The results showed that the polarization resistance of the DCPD-coated surface is about 25 times higher than that of non-coated surface. The CaP electro-deposition process increased the activation energy of corrosion process.

  18. Preparation of calcium phosphate glass-ceramics and their coating on titanium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kasuga, T.; Nogami, M. [Nagoya Inst. of Tech. (Japan). Dept. of Materials Science and Engineering; Niinomi, M. [Toyohashi Univ. of Technology (Japan). Dept. of Production Systems Engineering

    2001-07-01

    Novel silica-free calcium phosphate glass-ceramics was prepared by heating a compact of 60CaO . 30P{sub 2}O{sub 5} . 3TiO{sub 2} . 7Na{sub 2}O glass powders. When powder-compacts of the glasses were heated at 850 C, they crystallized and subsequently sintered, resulting in glass-ceramics containing {beta}Ca{sub 3}(PO{sub 4}){sub 2} and {beta}-Ca{sub 2}P{sub 2}O{sub 7} crystalline phases. The glass-ceramics show relatively high mechanical strength of 100 {proportional_to} 120 MPa in bending and fracture toughness of K{sub IC} {approx} 1.9 MPa.m{sup 0.5}. Hydroxyapatite was formed newly on the surface of the glass-ceramic in simulated body fluid at 37 C. By heating a new type of titanium alloy (Ti-29Nb-13Ta-4.6Zr), on which the glass powders were placed, at 800 C in air, a glass-ceramic layer containing {beta}-Ca{sub 3}(PO{sub 4}){sub 2} crystal was found to be joined easily with the metal. The joining between the coating layer and the metal substrate is very strong in tensile bonding strength. (orig.)

  19. Grain Refinement of Permanent Mold Cast Copper Base Alloys

    Energy Technology Data Exchange (ETDEWEB)

    M.Sadayappan; J.P.Thomson; M.Elboujdaini; G.Ping Gu; M. Sahoo

    2005-04-01

    Grain refinement is a well established process for many cast and wrought alloys. The mechanical properties of various alloys could be enhanced by reducing the grain size. Refinement is also known to improve casting characteristics such as fluidity and hot tearing. Grain refinement of copper-base alloys is not widely used, especially in sand casting process. However, in permanent mold casting of copper alloys it is now common to use grain refinement to counteract the problem of severe hot tearing which also improves the pressure tightness of plumbing components. The mechanism of grain refinement in copper-base alloys is not well understood. The issues to be studied include the effect of minor alloy additions on the microstructure, their interaction with the grain refiner, effect of cooling rate, and loss of grain refinement (fading). In this investigation, efforts were made to explore and understand grain refinement of copper alloys, especially in permanent mold casting conditions.

  20. In vitro and in vivo evaluation of the surface bioactivity of a calcium phosphate coated magnesium alloy.

    Science.gov (United States)

    Xu, Liping; Pan, Feng; Yu, Guoning; Yang, Lei; Zhang, Erlin; Yang, Ke

    2009-03-01

    Magnesium has shown potential application as a bio-absorbable biomaterial, such as for bone screws and plates. In order to improve the surface bioactivity, a calcium phosphate was coated on a magnesium alloy by a phosphating process (Ca-P coating). The surface characterization showed that a porous and netlike CaHPO(4).2H(2)O layer with small amounts of Mg(2+) and Zn(2+) was formed on the surface of the Mg alloy. Cells L929 showed significantly good adherence and significantly high growth rate and proliferation characteristics on the Ca-P coated magnesium alloy (p<0.05) in in-vitro cell experiments, demonstrating that the surface cytocompatibility of magnesium was significantly improved by the Ca-P coating. In vivo implantations of the Ca-P coated and the naked alloy rods were carried out to investigate the bone response at the early stage. Both routine pathological examination and immunohistochemical analysis demonstrated that the Ca-P coating provided magnesium with a significantly good surface bioactivity (p<0.05) and promoted early bone growth at the implant/bone interface. It was suggested that the Ca-P coating might be an effective method to improve the surface bioactivity of magnesium alloy.

  1. Corrosion and wear protective composition modulated alloy coatings based on ternary Ni-P-X alloys

    DEFF Research Database (Denmark)

    Leisner, P.; Benzon, M. E.; Christoffersen, Lasse

    1996-01-01

    Scattered reporting in the litterature describes a number of ternary Ni-P-X alloyes (where X can be Co, Cr, Cu, Mo, Pd, Re or W) with promising corrosin and wear protective performance. Based on a systematic study of Ni-P-X alloys it is the intention to produce coatings with improved corrosion...

  2. Study and understanding of the ageing mechanisms in lead-calcium alloys; Etude et comprehension des mecanismes de vieillissement des alliages de plomb-calcium

    Energy Technology Data Exchange (ETDEWEB)

    Rossi, F

    2006-12-15

    The data available in the literature about ageing and over-ageing of lead-calcium alloys are often incomplete and inconsistent. It is undoubtedly due to the experimental difficulties encountered to observe the structure transformations which are numerous. As a result there is a certain confusion among the results of the different authors. Moreover, small variations in the process parameters and chemical composition may have some influence on the alloy behaviour. This work enabled us to obtain a set of TTT diagrams, more realistic and accurate than the ones available in the literature. Experimental techniques developed (particularly the preservation of the cold chain with is essential for the guaranty of the results repeatability), enabled particularly the study of the first transformations and better control the five stages of ageing and over-ageing. Our work have enabled to determine precisely the kinetics and the mechanisms of the transformations. This work constitutes a thorough analysis of the ageing and over-ageing of theses alloys. (author)

  3. Cast iron-base alloy for cylinder/regenerator housing

    Science.gov (United States)

    Witter, Stewart L.; Simmons, Harold E.; Woulds, Michael J.

    1985-01-01

    NASACC-1 is a castable iron-base alloy designed to replace the costly and strategic cobalt-base X-40 alloy used in the automotive Stirling engine cylinder/generator housing. Over 40 alloy compositions were evaluated using investment cast test bars for stress-rupture testing. Also, hydrogen compatibility and oxygen corrosion resistance tests were used to determine the optimal alloy. NASACC-1 alloy was characterized using elevated and room temperature tensile, creep-rupture, low cycle fatigue, heat capacity, specific heat, and thermal expansion testing. Furthermore, phase analysis was performed on samples with several heat treated conditions. The properties are very encouraging. NASACC-1 alloy shows stress-rupture and low cycle fatigue properties equivalent to X-40. The oxidation resistance surpassed the program goal while maintaining acceptable resistance to hydrogen exposure. The welding, brazing, and casting characteristics are excellent. Finally, the cost of NASACC-1 is significantly lower than that of X-40.

  4. Calcium

    Science.gov (United States)

    ... and blood vessels contract and expand, to secrete hormones and enzymes and to send messages through the nervous system. It is important to get plenty of calcium in the foods you eat. Foods rich in calcium include Dairy products such as milk, cheese, and yogurt Leafy, green vegetables Fish with ...

  5. ELECTROSLAG CАSTING OF CHROMIUM BASED ALLOYS

    Directory of Open Access Journals (Sweden)

    Jong-Hoon Lee

    2015-01-01

    Full Text Available The analysis of the electroslag remelting (ESR process schemes was carried out. For heat-resistant material on the basis of chromium chosen scheme crucible ESR with nonconsumable bifilar electrodes. Developed and manufactured laboratory plant for studying the processes of electroslag remelting crucible chromium-based alloys. Samples from chromium based alloy were obtained.

  6. Non-alloyed Ni3Al based alloys – preparation and evaluation of mechanical properties

    Directory of Open Access Journals (Sweden)

    J. Malcharcziková

    2013-07-01

    Full Text Available The paper reports on the fabrication and mechanical properties of Ni3Al based alloy, which represents the most frequently used basic composition of nickel based intermetallic alloys for high temperature applications. The structure of the alloy was controlled through directional solidification. The samples had a multi-phase microstructure. The directionally solidified specimens were subjected to tensile tests with concurrent measurement of acoustic emission (AE. The specimens exhibited considerable room temperature ductility before fracture. During tensile testing an intensive AE was observed.

  7. Calcium and zirconium as texture modifiers during rolling and annealing of magnesium–zinc alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bohlen, Jan, E-mail: jan.bohlen@hzg.de; Wendt, Joachim; Nienaber, Maria; Kainer, Karl Ulrich; Stutz, Lennart; Letzig, Dietmar

    2015-03-15

    Rolling experiments were carried out on a ternary Mg–Zn–Ca alloy and its modification with zirconium. Short time annealing of as-rolled sheets is used to reveal the microstructure and texture development. The texture of the as-rolled sheets can be characterised by basal pole figures with split peak towards the rolling direction (RD) and a broad transverse angular spread of basal planes towards the transverse direction (TD). During annealing the RD split peaks as well as orientations in the sheet plane vanish whereas the distribution of orientations tilted towards the TD remains. It is shown in EBSD measurements that during rolling bands of twin containing structures form. During subsequent annealing basal orientations close to the sheet plane vanish based on a grain nucleation and growth mechanism of recrystallisation. Orientations with tilt towards the TD remain in grains that do not undergo such a mechanism. The addition of Zr delays texture weakening. - Highlights: • Ca in Mg–Zn-alloys contributes to a significant texture weakening during rolling and annealing. • Grain nucleation and growth in structures consisting of twins explain a texture randomisation during annealing. • Grains with transverse tilt of basal planes preferentially do not undergo a grain nucleation and growth mechanism. • Zr delays the microstructure and texture development.

  8. Excessively High Vapor Pressure of Al-based Amorphous Alloys

    Directory of Open Access Journals (Sweden)

    Jae Im Jeong

    2015-10-01

    Full Text Available Aluminum-based amorphous alloys exhibited an abnormally high vapor pressure at their approximate glass transition temperatures. The vapor pressure was confirmed by the formation of Al nanocrystallites from condensation, which was attributed to weight loss of the amorphous alloys. The amount of weight loss varied with the amorphous alloy compositions and was inversely proportional to their glass-forming ability. The vapor pressure of the amorphous alloys around 573 K was close to the vapor pressure of crystalline Al near its melting temperature, 873 K. Our results strongly suggest the possibility of fabricating nanocrystallites or thin films by evaporation at low temperatures.

  9. Calcium

    Science.gov (United States)

    ... from dietary supplements are linked to a greater risk of kidney stones, especially among older adults. But calcium from foods does not appear to cause kidney stones. For most people, other factors (such as not drinking enough fluids) probably have ...

  10. Biocompatibility of bio based calcium carbonate nanocrystals ...

    African Journals Online (AJOL)

    Material and Methods: Transmission and field emission scanning electron microscopy (TEM and FESEM) were used for the characterisation of CaCO3 nanocrystals. Cytotoxicity and genotoxic effect of calcium carbonate nanocrystals in cultured mouse embryonic fibroblast NIH 3T3 cell line using various bioassays including ...

  11. Tantalum modified ferritic iron base alloys

    Science.gov (United States)

    Oldrieve, R. E.; Blankenship, C. P. (Inventor)

    1977-01-01

    Strong ferritic alloys of the Fe-CR-Al type containing 0.4% to 2% tantalum were developed. These alloys have improved fabricability without sacrificing high temperature strength and oxidation resistance in the 800 C (1475 F) to 1040 C (1900 F) range.

  12. Corrosion resistance improvement of titanium base alloys

    Directory of Open Access Journals (Sweden)

    Mihai V. Popa

    2010-01-01

    Full Text Available The corrosion resistance of the new Ti-6Al-4V-1Zr alloy in comparison with ternary Ti-6Al-4V alloy in Ringer-Brown solution and artificial Carter-Brugirard saliva of different pH values was studied. In Ringer-Brown solution, the new alloy presented an improvement of all electrochemical parameters due to the alloying with Zr; also, impedance spectra revealed better protective properties of its passive layer. In Carter-Brugirard artificial saliva, an increase of the passive film thickness was proved. Fluoride ions had a slight negative influence on the corrosion and ion release rates, without to affect the very good stability of the new Ti-6Al-4V-1Zr alloy.

  13. Study on the bonding strength between calcium phosphate/chitosan composite coatings and a Mg alloy substrate

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Jie [School of Chemistry Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Pharmacy College, Jiamusi University, Jiamusi 154007 (China); Dai Changsong, E-mail: changsd@hit.edu.cn [School of Chemistry Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Wei Jie [School of Chemistry Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); School of Chemistry and Bioengineering, Suzhou Science Technology University, Suzhou 215009 (China); Wen Zhaohui, E-mail: wenzhaohui1968@163.com [Department of Neuro intern, First Affiliated Hospital of Harbin Medical University, Harbin 150001 (China)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Calcium phosphate/chitosan composite coatings on the MAO-AZ91D alloy were prepared. Black-Right-Pointing-Pointer The bonding force between the coating and the magnesium alloy was optimized. Black-Right-Pointing-Pointer The composite coating slowed down the corrosion rate of magnesium alloy in m-SBF. - Abstract: In order to improve the bonding strength between calcium phosphate/chitosan composite coatings and a micro-arc oxidized (MAO)-AZ91D Mg alloy, different influencing parameters were investigated in the process of electrophoretic deposition (EPD) followed by conversion in a phosphate buffer solution (PBS). Surface morphology and phase constituents of the as-prepared materials were investigated by using X-ray diffractometer (XRD), Fourier-transformed infrared spectrophotometer (FTIR), Raman spectrometer, scanning electron microscope (SEM) with an energy dispersive spectrometer (EDS), and a thermo gravimetric and differential thermal analyzer (TG-DTA). Scratch tests were carried out to study the bonding properties between the coatings and the substrates. In vitro immersion tests were conducted to determine the corrosion behaviors of samples with and without deposit layers through electrochemical experiments. In the EPD process, the acetic acid content in the electrophoresis suspension and the electrophoretic voltage played important roles in improving the bonding properties, while the contents of chitosan (CS) and nano-hydroxyapatite (nHA, Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}) in the suspension had less significant influences on the mechanical bonding strength. It was observed that the coatings showed the excellent bonding property when an electrophoretic voltage was in a range of 40-110 V with other reagent amounts as follows: acetic acid: 4.5 vol.%, CS {<=} 0.25 g, nHA {<=} 2.0 g in 200 ml of a CS-acetic acid aqueous solution and nHA {<=} 2.5 g in 300 ml of absolute ethanol. The morphology of the composite coating

  14. Cr{sub 2}Nb-based alloy development

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.T.; Tortorelli, P.F.; Horton, J.A. [Oak Ridge National Lab., TN (United States)] [and others

    1996-08-01

    Alloys of Cr-Cr{sub 2}Nb with exceptionally high strength at 1200{degrees}C have been developed. However, these compositions suffer from limited ductility and toughness at room temperature. Despite improvements from processing modifications, as-fabricated defects still limit room temperature mechanical behavior. In contrast, an alloy system with only a small mismatch of the coefficients of thermal expansion of the two phases, Cr-Cr{sub 2}Zr, showed good fabricability. However, these alloys are weaker than Cr-Cr{sub 2}Nb compositions at high temperatures and have poor oxidation resistance. Silicide coatings can provide high-temperature oxidation and sulfidation protection of these alloys. Improvements in room temperature mechanical properties of Laves-phase-strengthened alloys will rely on further development based on increasing the ductility of the matrix phase by impurity control and compositional modifications.

  15. Hydrogen treatment of titanium based alloys

    Science.gov (United States)

    Losertová, M.; Hartmann, M.; Schindler, I.; Drápala, J.

    2017-11-01

    The positive effect of the hydrogen on hot deformation behaviour at 700 and 750 °C was investigated after thermal hydrogen treatment of Ti6Al4V and Ti26Nb alloys. Comparing the results obtained for the non-hydrogenated and hydrogenated specimens of both alloys, it was found that the hydrogen content as high as 1325 wt. ppm has an obvious benefit effect on high temperature deformation behaviour in the Ti6Al4V alloy by stabilizing beta phase and lowering thermal deformation resistance. In the case of Ti26Nb alloy the hydrogen content of 2572 wt. ppm suppressed stress instabilities during hot compression but slightly increased thermal deformation resistance. The microstructure study was performed before and after the isothermal compression tests on the specimens in hydrogenated as well as in non-hydrogenated condition. The hydrogen amounts in the specimens were measured by means of an analyser LECO RH600.

  16. MULTIFUNCTIONAL CAGULANTS BASED ON HIDROCARBOALUMINATES CALCIUM

    Directory of Open Access Journals (Sweden)

    Ekaterina Viktorovna Siziakova

    2017-03-01

    Full Text Available The article describes harmful factors from the environmental point of view that accompany almost all stages of production of non-ferrous metals. Due to the fact that this industry requires large volume of water, these factors require special attention when cleaning wastewater. The contamination of wastewater by non-ferrous metallurgy is characterized by metal ions, particulate pollutants, acids, SAS, etc, The common feature of all these substances is harmfulness, however, they are often very aggressive and toxic also. The article focuses on the possible use of hidrocarboaluminates calcium as an active ion exchanger for cleanup wastewater metallurgical production.

  17. Microstructures and oxidation behavior of some Molybdenum based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Pratik Kumar [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    The advent of Ni based superalloys revolutionized the high temperature alloy industry. These materials are capable of operating in extremely harsh environments, comprising of temperatures around 1050 C, under oxidative conditions. Demands for increased fuel efficiency, however, has highlighted the need for materials that can be used under oxidative conditions at temperatures in excess of 1200 C. The Ni based superalloys are restricted to lower temperatures due to the presence of a number of low melting phases that melt in the 1250 - 1450 C, resulting in softening of the alloys above 1000 C. Therefore, recent research directions have been skewed towards exploring and developing newer alloy systems. This thesis comprises a part of such an effort. Techniques for rapid thermodynamic assessments were developed and applied to two different systems - Mo-Si alloys with transition metal substitutions (and this forms the first part of the thesis) and Ni-Al alloys with added components for providing high temperature strength and ductility. A hierarchical approach towards alloy design indicated the Mo-Ni-Al system as a prospective candidate for high temperature applications. Investigations on microstructures and oxidation behavior, under both isothermal and cyclic conditions, of these alloys constitute the second part of this thesis. It was seen that refractory metal systems show a marked microstructure dependence of oxidation.

  18. Structural studies of calcium phosphate doped with titanium and zirconium obtained by high-energy mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Silva, C C; Sombra, A S B [Telecommunications and Materials Science and Engineering Laboratory (LOCEM), Physics Department, Federal University of Ceara, Campus do Pii, Postal Code 6030, 60455-760, Fortaleza-Ceara (Brazil)], E-mail: sombra@fisica.ufc.br

    2009-12-15

    In this paper, we present a new variation of the solid-state procedure on the synthesis of bioceramics with titanium (CapTi) and zirconium (CapZr), considering that zirconium (ZrO{sub 2}) and titanium oxide (TiO{sub 2}) are strengthening agents, due to their superb force and fracture toughness. The high efficiency of the calcination process opens a new way of producing commercial amounts of nanocrystalline bioceramics. In this work, a new variation of the solid-state procedure method was used to produce nanocrystalline powders of titanium and zirconium, using two different experimental chemical routes: CapTi: Ca(H{sub 2}PO{sub 4}){sub 2}+TiO{sub 2} and CapZr: Ca(H{sub 2}PO{sub 4}){sub 2}+ZrO{sub 2}. The powders were submitted to calcination processes (CapTic and CapZrc) at 800, 900 and 1000 deg. C. The calcium titanium phosphate phase, CaTi{sub 4}P{sub 6}O{sub 24}, was obtained in the CapTic reaction and the calcium zirconium phosphate, CaZr{sub 4}P{sub 6}O{sub 24}, was obtained in the CapZrc reaction. The obtained ceramics were characterized by x-ray powder diffraction (XRD), infrared (IR) spectroscopy, Raman scattering spectroscopy (RSS) and scanning electron microscopy (SEM) analysis. This method was compared with the milling process (CapTim and CapZrm), where in the last process the melting is not necessary and the powder obtained is nanocrystalline. The calcium titanium phosphate phase, CaTi{sub 4}P{sub 6}O{sub 24}, was obtained in the reaction CapTim, but in CapZrm the formation of any calcium phosphate phase even after 15 h of dry mechanical alloying was not observed.

  19. Oxidation Behavior of TiAl-Based Alloy Modified by Double-Glow Plasma Surface Alloying with Cr-Mo

    Science.gov (United States)

    Wei, Xiangfei; Zhang, Pingze; Wang, Qiong; Wei, Dongbo; Chen, Xiaohu

    2017-07-01

    A Cr-Mo alloyed layer was prepared on a TiAl-based alloy using plasma surface alloying technique. The isothermal oxidation kinetics of the untreated and treated samples was examined at 850 °C. The microstructure and phase composition of the alloyed layer were analyzed by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray powder diffraction (XRD). The morphology and constituent of the oxide scales were also analyzed. The results indicated that the oxidation resistance of TiAl was improved significantly after the alloying treatment. The oxide scale eventually became a mixture of Al2O3, Cr2O3 and TiO2. The oxide scale was dense and integrated throughout the oxidation process. The improvement was mainly owing to the enhancing of scale adhesion and the preferential oxidation of aluminum brought by the alloying effect for TiAl-based alloy.

  20. EXAFS investigation on microstructure of La-based alloy deuteride

    CERN Document Server

    Chen Bo Fei; Xie Chao Mei; Chen Xi Ping; Liu Li Juan; Xie Ya Ning; Hu Tian Dou; Zhang Jing

    2002-01-01

    Extended X-ray absorption fine structure (EXAFS) spectra were measured to investigate the microstructure of La-based alloy deuteride. The radial structural functions of LaNi sub 4 sub . sub 2 sub 5 Al sub 0 sub . sub 7 sub 5 D sub x samples were obtained and the comparisons among different samples were performed. The results show that removal of deuterium is fast in La-Ni-Al hydrogen storage alloys under non-airtight condition

  1. Calcium phosphate coatings on magnesium alloys for biomedical applications: a review.

    Science.gov (United States)

    Shadanbaz, Shaylin; Dias, George J

    2012-01-01

    Magnesium has been suggested as a revolutionary biodegradable metal for use as an orthopaedic material. As a biocompatible and degradable metal, it has several advantages over the permanent metallic materials currently in use, including eliminating the effects of stress shielding, improving biocompatibility concerns in vivo and improving degradation properties, removing the requirement of a second surgery for implant removal. The rapid degradation of magnesium, however, is a double-edged sword as it is necessary to control the corrosion rates of the materials to match the rates of bone healing. In response, calcium phosphate coatings have been suggested as a means to control these corrosion rates. The potential calcium phosphate phases and their coating techniques on substrates are numerous and can provide several different properties for different applications. The reactivity and low melting point of magnesium, however, require specific parameters for calcium phosphate coatings to be successful. Within this review, an overview of the different calcium phosphate phases, their properties and their behaviour in vitro and in vivo has been provided, followed by the current coating techniques used for calcium phosphates that may be or may have been adapted for magnesium substrates. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  2. Corrosion of nickel-based dental casting alloys.

    Science.gov (United States)

    Wylie, Christopher M; Shelton, Richard M; Fleming, Garry J P; Davenport, Alison J

    2007-06-01

    To study the microstructure, corrosion behaviour and cell culture response of two nickel-based dental casting alloys before and after a heat treatment to simulate porcelain firing. The microstructure was studied using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Corrosion behaviour was evaluated by electrochemical measurements in artificial saliva at different values of pH in the presence of a crevice. 3T3 mouse fibroblasts were exposed indirectly to alloy specimens and the number of viable cells counted after 3 and 6 days compared to a control culture. Small changes in microstructure were observed after heat treatment but had a negligible effect on the corrosion properties in the conditions tested. The alloy with a lower bulk level of Cr (12.6 wt.%) showed lower corrosion resistance, indicated by an increased passive current density and this stability was greatly reduced at pH 2.5, where crevice corrosion was observed. Selective dissolution occurred at regions within the microstructure containing lower levels of Cr and Mo. Furthermore, the proliferation of 3T3 mouse fibroblasts was reduced (pcorrosion resistance, which was associated with a more uniform distribution of Cr in the alloy microstructure. The presence of crevices combined with an inhomogeneous distribution of Cr in the microstructure can lead to accelerated corrosion of Ni-based alloys with lower Cr contents. This effect can be avoided by increasing the Cr content of the alloy.

  3. Effects of calcium ion incorporation on bone healing of Ti6Al4V alloy implants in rabbit tibiae.

    Science.gov (United States)

    Park, Jin-Woo; Park, Kwang-Bum; Suh, Jo-Young

    2007-08-01

    The biocompatibility of calcium ion (Ca)-incorporated Ti6Al4V alloy implants, produced by hydrothermal treatment using a Ca-containing solution, was investigated. The surface characteristics were evaluated by scanning electron microscopy, thin-film X-ray diffractometry, Auger electron spectroscopy, and stylus profilometry. The viability of MC3T3-E1 cells on Ca-incorporated machined Ti6Al4V surfaces with different oxide thicknesses was compared with that on untreated machined Ti6Al4V surfaces with MTT assay. The osteoconductivity of the Ca-incorporated Ti6Al4V implants was evaluated by removal torque testing and histomorphometric analysis after 6 weeks of implantation in rabbit tibiae. Our results show that hydrothermal treatment with a Ca-containing solution produced a crystalline CaTiO(3) layer on Ti6Al4V surfaces, and calcium ions were gradually incorporated throughout the oxide layer. After immersion in Hank's balanced salt solution, a considerable apatite deposition was observed on all surfaces of the Ca-incorporated samples. Significant increases in cell viability (pTi6Al4V implants compared with those for untreated Ti6Al4V implants.

  4. Durability studies on the high calcium flyash based GPC ...

    African Journals Online (AJOL)

    Geopolymer concrete is an environment friendly green concrete which is comparatively of lower carbon footprint. Most of the studies reported is about the development of low calcium flyash based GPC only and and that too mostly on achieving the compressive strength and not much on its durability related properties.

  5. Mercury Control with Calcium-Based Sorbents and Oxidizing Agents

    Energy Technology Data Exchange (ETDEWEB)

    Thomas K. Gale

    2005-07-01

    This Final Report contains the test descriptions, results, analysis, correlations, theoretical descriptions, and model derivations produced from many different investigations performed on a project funded by the U.S. Department of Energy, to investigate calcium-based sorbents and injection of oxidizing agents for the removal of mercury. Among the technologies were (a) calcium-based sorbents in general, (b) oxidant-additive sorbents developed originally at the EPA, and (c) optimized calcium/carbon synergism for mercury-removal enhancement. In addition, (d) sodium-tetrasulfide injection was found to effectively capture both forms of mercury across baghouses and ESPs, and has since been demonstrated at a slipstream treating PRB coal. It has been shown that sodium-tetrasulfide had little impact on the foam index of PRB flyash, which may indicate that sodium-tetrasulfide injection could be used at power plants without affecting flyash sales. Another technology, (e) coal blending, was shown to be an effective means of increasing mercury removal, by optimizing the concentration of calcium and carbon in the flyash. In addition to the investigation and validation of multiple mercury-control technologies (a through e above), important fundamental mechanism governing mercury kinetics in flue gas were elucidated. For example, it was shown, for the range of chlorine and unburned-carbon (UBC) concentrations in coal-fired utilities, that chlorine has much less effect on mercury oxidation and removal than UBC in the flyash. Unburned carbon enhances mercury oxidation in the flue gas by reacting with HCl to form chlorinated-carbon sites, which then react with elemental mercury to form mercuric chloride, which subsequently desorbs back into the flue gas. Calcium was found to enhance mercury removal by stabilizing the oxidized mercury formed on carbon surfaces. Finally, a model was developed to describe these mercury adsorption, desorption, oxidation, and removal mechanisms, including

  6. Characterization of the microstructure in Mg based alloy

    KAUST Repository

    Kutbee, Arwa T

    2013-06-01

    The cast products Mg–Sn based alloys are promising candidates for automobile industries, since they provide a cheap yet thermally stable alternative to existing alloys. One drawback of the Mg–Sn based alloys is their insufficient hardness. The hardenability can be improved by engineering the microstructure through additions of Zn to the base alloy and selective aging conditions. Therefore, detailed knowledge about the microstructural characteristics and the role of Zn to promote precipitation hardening is essential for age hardenable Mg-based alloys. In this work, microstructural investigation of the Mg–1.4Sn–1.3Zn–0.1Mn (at.%) precipitation system was performed using TEM. The chemical composition of the precipitates was analyzed using EDS. APT was employed to obtain precise chemical information on the distribution of Zn in the microstructure. It was found from microstructural studies that different precipitates with varying sizes and phases were present; lath-shaped precipitates of the Mg2Sn phase have an incoherent interface with the matrix, unlike the lath-shaped MgZn2 precipitates. Furthermore, nano-sized precipitates dispersed in the microstructure with short-lath morphology can either be enriched with Sn or Zn. On the other hand, APT analysis revealed the strong repulsion between Sn and Zn atoms in a portion of the analysis volume. However, larger reconstruction volume required to identify the role of Zn is still limited to the optimization of specimen preparation.

  7. Heat resistant nickel base alloy excellent in workability and high temperature strength properties

    Energy Technology Data Exchange (ETDEWEB)

    Susukida, H.; Itoh, H.; Kawai, H.; Kojima, T.; Sahira, K.; Takeiri, T.; Tsuji, I.; Yuge, M.

    1984-10-02

    A heat resistant nickel base alloy which is excellent in not only hot and cold workability but also high temperature strength properties and which also possesses satisfactory oxidation resistance. The nickel base alloy consists essentially of 0.001-0.15 percent carbon, 0.0005-0.05 percent calcium, 20.0-126.0 percent chromium, 4.7-9.4 percent cobalt, 5.0-16.0 percent molybdenum, 0.5-4.0 percent tungsten, with the total of molybdenum plus tungsten being from 9.0 to 16.5 percent, and the balance nickel and inevitable impurities. The alloy may further contain one selected from the group consisting of (1) 0.3-1.5 percent aluminum and 0.1-1.0 percent titanium, (2) 0.001-0.30 percent at least one of yttrium and rare earth elements, and (3) 0.001-1.0 percent at least one of niobium, vanadium and tantalum, whereby the aforementioned characteristics are further enhanced.

  8. Effects of alloying elements and temperature on the elastic properties of W-based alloys by first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Yong-Jie, E-mail: yoh5120@psu.edu [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Shang, Shun-Li; Wang, Yi [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Darling, Kristopher A.; Butler, Brady G.; Kecskes, Laszlo J. [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, RDRL-WMM-F, Aberdeen Proving Ground, MD 21005 (United States); Liu, Zi-Kui [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802 (United States)

    2016-06-25

    The influence of various transition alloying elements (X's) on the elastic properties of W-based alloys has been studied via first-principles calculations on the basis of density functional theory. Here, nineteen transition metal alloying elements (X) are considered: Ti, V, Cr, Fe, Co, Ni, Y, Zr, Nb, Mo, Ru, Rh, Pd, Hf, Ta, Re, Os, Ir, and Pt. It is found that (i) the bulk modulus of the dilute W-X alloy decreases with increasing its equilibrium volume, particularly, for the alloying elements in the same period; (ii) all of the alloying elements decrease the shear modulus of BCC W; and (iii) the largest decrease of elastic properties of W is due to alloying element Y. In addition, it is shown that the changes of elastic properties of W caused by the alloying elements are traceable from the electron charge density distribution, resulting in a bonding distortion between W and the alloying atoms. Using the quasi-static approach based on the Debye model, the elastic properties of these W-X alloys at finite temperatures are predicted. Calculated properties of BCC W and the W-X alloys are in favorable agreement with available experimental measurements. - Highlights: • The effects of nineteen metal elements on the elastic properties of W are studied. • The elastic properties at finite temperatures are predicted by the Debye model. • The alloying effects can be traceable from the changes of electronic structure. • The possibly promising alloying elements to soften BCC W are suggested.

  9. Durable pd-based alloy and hydrogen generation membrane thereof

    Science.gov (United States)

    Benn, Raymond C.; Opalka, Susanne M.; Vanderspurt, Thomas Henry

    2010-02-02

    A durable Pd-based alloy is used for a H.sub.2-selective membrane in a hydrogen generator, as in the fuel processor of a fuel cell plant. The Pd-based alloy includes Cu as a binary element, and further includes "X", where "X" comprises at least one metal from group "M" that is BCC and acts to stabilize the .beta. BCC phase for stability during operating temperatures. The metal from group "M" is selected from the group consisting of Fe, Cr, Nb, Ta, V, Mo, and W, with Nb and Ta being most preferred. "X" may further comprise at least one metal from a group "N" that is non-BCC, preferably FCC, that enhances other properties of the membrane, such as ductility. The metal from group "N" is selected from the group consisting of Ag, Au, Re, Ru, Rh, Y, Ce, Ni, Ir, Pt, Co, La and In. The at. % of Pd in the binary Pd--Cu alloy ranges from about 35 at. % to about 55 at. %, and the at. % of "X" in the higher order alloy, based on said binary alloy, is in the range of about 1 at. % to about 15 at. %. The metals are selected according to a novel process.

  10. Poor glass-forming ability of Fe-based alloys

    DEFF Research Database (Denmark)

    Zheng, H.J.; Hu, L.N.; Zhao, X.

    2017-01-01

    processes. By using the concept of fluid cluster and supercooled liquid fragility in metallic liquids, it has been found that this dynamic transition makes the Fe-based supercooled liquids become more unstable, which leads to the poor GFA of Fe-based alloys. Further, it has been found that the degree...

  11. Several Issues in the Development of Ti-Nb-Based Shape Memory Alloys

    Science.gov (United States)

    Kim, Hee Young; Miyazaki, Shuichi

    2016-12-01

    Ni-free Ti-based shape memory alloys, particularly Ti-Nb-based alloys, have attracted increasing attraction since the early 2000s due to their wide application potentials in biomedical fields. Recently, there has been significant progress in understanding the martensitic transformation behavior of Ti-Nb-based alloys and many novel superelastic alloys have been developed. The superelastic properties of Ti-Nb-based alloys have been remarkably improved through the optimization of alloying elements and microstructure control. In this paper, in order to explore and establish the alloy design strategy, several important issues in the development of Ti-Nb-based shape memory alloys are reviewed. Particularly, the effects of alloying elements on the martensitic transformation temperature and the transformation strain are analyzed. The effects of omega phase and texture on the superelastic properties are also discussed.

  12. Melting and casting of FeAl-based cast alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K. [Oak Ridge National Lab., TN (United States); Wilkening, D. [Columbia Falls Aluminum Co., Columbia Falls, MT (United States); Liebetrau, J.; Mackey, B. [AFFCO, L.L.C., Anaconda, MT (United States)

    1998-11-01

    The FeAl-based intermetallic alloys are of great interest because of their low density, low raw material cost, and excellent resistance to high-temperature oxidation, sulfidation, carburization, and molten salts. The applications based on these unique properties of FeAl require methods to melt and cast these alloys into complex-shaped castings and centrifugal cast tubes. This paper addresses the melting-related issues and the effect of chemistry on the microstructure and hardness of castings. It is concluded that the use of the Exo-Melt{trademark} process for melting and the proper selection of the aluminum melt stock can result in porosity-free castings. The FeAl alloys can be melted and cast from the virgin and revert stock. A large variation in carbon content of the alloys is possible before the precipitation of graphite flakes occurs. Titanium is a very potent addition to refine the grain size of castings. A range of complex sand castings and two different sizes of centrifugal cast tubes of the alloy have already been cast.

  13. Cr{sub 2}Nb-based alloy development

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.T.; Tortorelli, P.F.; Horton, J.A.; Easton, D.S.; Heatherly, L.

    1996-06-01

    The objective of this work is to develop a new generation of structural materials based on intermetallic alloys for use at high temperatures in advanced fossil energy conversion systems. Target applications of such ultrahigh strength alloys include hot components (for example, air heat exchangers) in advanced energy conversion systems and heat engines. However, these materials may also find use as wear-resistant parts in coal handling systems (for example, nozzles), drill bits for oil/gas wells, and valve guides in diesel engines. One potential class of such alloys is that based on Cr-Cr{sub 2}Nb alloys. The intermetallic phase, Cr{sub 2}Nb, with a complex cubic structure (C-15) has been selected for initial development because of its high melting point (1770{degrees}C), relatively low material density (7.7 g/cm{sup 2}), and excellent high-temperature strength (at 1000 to 1250{degrees}C). This intermetallic phase, like many other Laves phases, has a wide range of compositional homogeneity suggesting the possibility of improving its mechanical and metallurgical properties by alloying additions.

  14. Calcium intake by adolescents: a population-based health survey

    Directory of Open Access Journals (Sweden)

    Daniela de Assumpção

    2016-06-01

    Full Text Available Abstract Objective To analyze calcium intake in adolescents according to sociodemographic variables, health-related behaviors, morbidities, and body mass index. Methods This was a cross-sectional population-based study, with a two-stage cluster sampling that used data from a survey conducted in Campinas, São Paulo, Brazil, between 2008 and 2009. Food intake was assessed using a 24-hour dietary recall. The study included 913 adolescents aged 10-19 years. Results Average nutrient intake was significantly lower in the segment with lower education of the head of the family and lower per capita family income, in individuals from other cities or states, those who consumed fruit less than four times a week, those who did not drink milk daily, those who were smokers, and those who reported the occurrence of headaches and dizziness. Higher mean calcium intake was found in individuals that slept less than seven hours a day. The prevalence of calcium intake below the recommendation was 88.6% (95% CI: 85.4-91.2. Conclusion The results alert to an insufficient calcium intake and suggest that certain subgroups of adolescents need specific strategies to increase the intake of this nutrient.

  15. Calcium intake by adolescents: a population-based health survey.

    Science.gov (United States)

    de Assumpção, Daniela; Dias, Marcia Regina Messaggi Gomes; de Azevedo Barros, Marilisa Berti; Fisberg, Regina Mara; de Azevedo Barros Filho, Antonio

    2016-01-01

    To analyze calcium intake in adolescents according to sociodemographic variables, health-related behaviors, morbidities, and body mass index. This was a cross-sectional population-based study, with a two-stage cluster sampling that used data from a survey conducted in Campinas, São Paulo, Brazil, between 2008 and 2009. Food intake was assessed using a 24-hour dietary recall. The study included 913 adolescents aged 10-19 years. Average nutrient intake was significantly lower in the segment with lower education of the head of the family and lower per capita family income, in individuals from other cities or states, those who consumed fruit less than four times a week, those who did not drink milk daily, those who were smokers, and those who reported the occurrence of headaches and dizziness. Higher mean calcium intake was found in individuals that slept less than seven hours a day. The prevalence of calcium intake below the recommendation was 88.6% (95% CI: 85.4-91.2). The results alert to an insufficient calcium intake and suggest that certain subgroups of adolescents need specific strategies to increase the intake of this nutrient. Copyright © 2015 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

  16. High temperature hardness of steels and iron-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Torres, H., E-mail: torres@ac2t.at; Varga, M.; Ripoll, M. Rodríguez

    2016-08-01

    Hot hardness, related to the mechanical strength and wear resistance of materials at high temperatures, has been measured from room temperature up to 800 °C for a comprehensive set of iron-based alloys having different microstructures and chemical compositions. The results obtained suggest the existence of several softening regimes with increasing temperatures, also with a massive hardness drop observed to begin at temperatures close to 0.5 times the melting temperature for most of the chosen alloys. Austenitic steel grades were also observed to show a significant softening behaviour at moderate temperatures compared to ferritic and martensitic alloys, attributed to the dislocation dynamics of face cubic centred alloys. The exact nature of the temperature dependence shown by hardness has been proposed to adopt the form of an exponential Arrhenius equation. Another model suggested in the available literature is also discussed within this context. Additionally, the role of alloying elements has been correlated to the softening behaviour. Molybdenum or boron were found to slow down the softening behaviour, while carbide-forming elements such as vanadium and tungsten were found to be beneficial for room temperature hardness.

  17. Electrochemical characteristics of titanium-based hydrogen storage alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ramya, K.; Rajalakshmi, N.; Sridhar, P.; Sivasankar, B

    2004-06-30

    Zirconium-substituted TiMn{sub 2}-based hydrogen storage alloy electrodes were prepared and their electrochemical characteristics have been evaluated in 6 M aqueous KOH solution. The electrode characteristics of Ti{sub 1-x}Zr{sub x}Mn{sub 1.6}Ni{sub 0.4} (x=0.1 and 0.2) alloys such as discharge capacity, high rate capability and cycle life were evaluated. The alloy Ti{sub 0.9}Zr{sub 0.1}Mn{sub 1.6}Ni{sub 0.4} was found to have higher capacity than Ti{sub 0.8}Zr{sub 0.2}Mn{sub 1.6}Ni{sub 0.4} alloy. The exchange current density was also higher for Ti{sub 0.9}Zr{sub 0.1}Mn{sub 1.6}Ni{sub 0.4} alloy.

  18. Advanced nickel base alloys for high strength, corrosion applications

    Science.gov (United States)

    Flinn, John E.

    1998-01-01

    Improved nickel-base alloys of enhanced strength and corrosion resistance, produced by atomization of an alloy melt under an inert gas atmosphere and of composition 0-20Fe, 10-30Cr, 2-12Mo, 6 max. Nb, 0.05-3 V, 0.08 max. Mn, 0.5 max. Si, less than 0.01 each of Al and Ti, less than 0.05 each of P and S, 0.01-0.08C, less than 0.2N, 0.1 max. 0, bal. Ni.

  19. Improved Mg-based alloys for hydrogen storage

    Energy Technology Data Exchange (ETDEWEB)

    Sapru, K.; Ming, L.; Stetson, N.T.; Evans, J. [Energy Conversion Devices, Inc., Troy, MI (United States)

    1998-08-01

    The overall objective of this on-going work is to develop low temperature alloys capable of reversibly storing at least 3 wt.% hydrogen, allowing greater than for 2 wt.% at the system level which is required by most applications. Surface modification of Mg can be used to improve its H-sorption kinetics. The authors show here that the same Mg-transition metal-based multi-component alloy when prepared by melt-spinning results in a more homogeneous materials with a higher plateau pressure as compared to preparing the material by mechanical grinding. They have also shown that mechanically alloyed Mg{sub 50}Al{sub 45}Zn{sub 5} results in a sample having a higher plateau pressure.

  20. Positron lifetime study in dilute electron irradiated lead based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Moya, G. [Lab. de Physique des Materiaux, 13 Marseille (France); Li, X.H. [D.R.F.M., S.P.2.M., M.P., C.E.N.G., 38 Grenoble (France); Menai, A. [Lab. de Physique des Materiaux, 13 Marseille (France); Kherraz, M. [Lab. de Physique des Materiaux, 13 Marseille (France); Amenzou, H. [Lab. de Physique des Materiaux, 13 Marseille (France); Bernardini, J. [Lab. de Metallurgie, 13 Marseille (France); Moser, P. [D.R.F.M., S.P.2.M., M.P., C.E.N.G., 38 Grenoble (France)

    1995-06-01

    The recovery of defects in two dilute solute-lead based alloys (Pb-Au, Pb-Cd) has been followed by positron lifetime measurements after a 3 MeV electron irradiation at 20 K. Two distinct isochronal annealing stages, the first centred at about 150 K and the other around 275 K, are to be observed as exactly the same in both the pure Pb and dilute alloys but the vacancy clustering over the second stage seen in lead and Pb-Au is completely suppressed in the Pb-Cd alloy. The results are discussed in terms of a high interaction between the cadmium atoms and vacancies in agreement with a probable presence of atomic excitons. (orig.)

  1. NiTi shape memory alloys coated with calcium phosphate by plasma-spraying. Chemical and biological properties

    Energy Technology Data Exchange (ETDEWEB)

    Prymak, O.; Epple, M. [Institute of Inorganic Chemistry, University of Duisburg-Essen, D-45117 Essen (Germany); Bogdansk, D.; Esenwein, S.A.; Koeller, M. [Department of Surgery, BG Kliniken Bergmannsheil - Universitaetsklinik, Buerkle-de-la-Camp-Platz 1, D-44780 Bochum (Germany)

    2004-05-01

    Plates of superelastic nickel-titanium shape memory alloy (NiTi) were coated with calcium phosphate (hydroxyapatite) by high-temperature plasma-spraying. The porous layer of about 100 {mu}m thickness showed a good adhesion to the metallic substrate that withstood bending of the plate but detached upon cutting the plate. The biocompatibility was tested by cultivation of blood cells (whole blood and isolated granulocytes [a subpopulation of blood leukocytes]). As substrates, pure NiTi, plasma-spray-coated NiTi and calcium phosphate-coated NiTi prepared by a dip-coating process were used. The adhesion of whole blood cells to all materials was not significantly different. In contrast, isolated granulocytes showed an increased adhesion to both calcium phosphate-coated NiTi samples. However, compared to non-coated NiTi or dip-coated NiTi, the number of dead granulocytes adherent to plasma-sprayed surfaces was significantly increased for isolated granulocytes (p<0.01). (Abstract Copyright [2004], Wiley Periodicals, Inc.) [German] Bleche aus superelastischer Nickel-Titan-Legierung (NiTi) wurden durch Hochtemperatur-Plasmaspritzen mit Calciumphosphat (Hydroxylapatit) beschichtet. Die Haftung der ca. 100 {mu}m starken poroesen Schicht auf der metallischen Unterlage ist so gut, dass das Blech gebogen werden kann. Das Schneiden des Bleches fuehrte allerdings zur Abloesung der Schicht. Die Biokompatibilitaet der beschichteten Bleche wurde im Zellkulturexperiment mit Blutzellen (Vollblut und isolierte Granulozyten, [eine Subpopulation von Blutleukozyten]) untersucht. Zum Vergleich wurden reines NiTi und Calciumphosphat-beschichtetes NiTi (hergestellt durch einen Tauchprozess) ebenfalls in der Zellkultur untersucht. Die Adhaerenz der Vollblutzellen an die Materialien war nicht signifikant unterschiedlich. Im Gegensatz dazu zeigten isolierte Granulozyten eine hoehere Adhaesion auf beiden Calciumphosphat-beschichteten NiTi-Proben. Die Anzahl von toten Granulozyten war auf

  2. Purely inorganic coatings based on nanoparticles for magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Feil, Florian [DECHEMA e.V., Karl-Winnacker-Institut, Frankfurt am Main (Germany)], E-mail: feil@dechema.de; Fuerbeth, Wolfram; Schuetze, Michael [DECHEMA e.V., Karl-Winnacker-Institut, Frankfurt am Main (Germany)

    2009-03-30

    The chemical nanotechnology is offering a chance to apply stable inorganic coatings onto magnesium alloys. The cast alloy AZ91 as well as the wrought alloy AZ31 could be dip-coated with aqueous dispersions based on commercially available silica particles and various additives. The high surface activity of the nanoparticles and appropriate additives, e.g. boron, aluminium or alkali salts, help to densify these coatings under moderate conditions even suitable for those thermally precarious magnesium alloys. Another coating technique is based on the electrophoretic deposition of nanoparticles already containing all sintering aids. These particles could be synthesised by a base-catalysed sol-gel process. Polydiethoxysiloxane can act as an adhesion promoter for these coatings. Additionally concentration gradients of different oxides within these particles can adjust the coating properties, too. Usually single coatings are very thin (200-500 nm). However, multiple coating applications as well as a process involving special particle mixtures lead to coatings with a thickness of up to several micrometers. Even after thermal treatment at 200 or 400 deg. C these coatings stay crack-free. The composition and texture of these coatings were studied using IR, atomic force microscopy (AFM), scanning electron microscopy (SEM) and other techniques. Electrochemical impedance measurements show an improvement of the corrosion performance by these coatings. The coating resistance is improving with the coating thickness.

  3. Elimination of Iron Based Particles in Al-Si Alloy

    Directory of Open Access Journals (Sweden)

    Bolibruchová D.

    2015-03-01

    Full Text Available This paper deals with influence on segregation of iron based phases on the secondary alloy AlSi7Mg0.3 microstructure by chrome. Iron is the most common and harmful impurity in aluminum casting alloys and has long been associated with an increase of casting defects. In generally, iron is associated with the formation of Fe-rich phases. It is impossible to remove iron from melt by standard operations, but it is possible to eliminate its negative influence by addition some other elements that affect the segregation of intermetallics in less harmful type. Realization of experiments and results of analysis show new view on solubility of iron based phases during melt preparation with higher iron content and influence of chrome as iron corrector of iron based phases. By experimental work were used three different amounts of AlCr20 master alloy a three different temperature of chill mold. Our experimental work confirmed that chrome can be used as an iron corrector in Al-Si alloy, due to the change of intermetallic phases and shortening their length.

  4. Replacement of Cobalt base alloys hardfacing by NOREM alloy; EDF experience and development, some metallurgical considerations. Valves application (CLAMA, RAMA)

    Energy Technology Data Exchange (ETDEWEB)

    Carnus, M. [EDF DPN UTO Direction Expertise Technique, Noisy le Grand (France); Confort, X. [VELAN SAS, Lyon (France)

    2011-07-01

    Cobalt base alloys, such as Stellite 6 and 21, are used extensively in applications where superior resistance to wear and corrosion are required. However the use of Cobalt alloys hardfacing materials, especially on valves, is a major contributor to the level of radioactive contamination of nuclear facilities. NOREM alloys, an iron base and cobalt free materials, have been developed through an Electric Power Research Institute (EPRI) long running program during the eighties as an alternative of Stellite. This alloy has relatively good weldability properties, it was developed initially for repairing Stellite hardfacing (deposit over existing hardfacing alloys). This alloy has good corrosion resistance properties associated with elevated hardness (HRC 36-42). Technological properties (such as galling resistance, wear resistance) have been evaluated through different testing programs led by EPRI, AECL(Atomic Energy of Canada Limited), Valves manufacturers, EDF and others during the nineties. More recently EDF (for replacement of globe valves) has carried out testing program focused on weld deposit chemistry and mechanical properties. NOREM is a candidate for replacement of stellite hardfacing on valves. However this alloy is not so versatile as stellite alloys regarding technological properties (such as wear resistance) at elevated temperature and under high contact pressure. As a consequence some limits have to be considered for application on valves operating at elevated temperature and under high contact pressure (> 20 Mpa). Examples of application on valves, from VELAN manufacturer, for EDF PWR equipment are given. The industrial feedback from installed equipment (CLAMA, RAMA) since 2006 on EDF PWR has been good

  5. High strength nickel base alloy, WAZ-16, for applications up to 2200 F

    Science.gov (United States)

    Waters, W. J.; Freche, J. C.

    1974-01-01

    Alloy product is high strength, high temperature nickel base material with higher incipient melting temperature than all known nickel base alloys. It is microstructurally stable and has high impact resistance both before and after prolonged thermal exposure. It contains relatively few alloying constitutents and low content of expensive and rare metals.

  6. Nitriding behavior of Ni and Ni-based binary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Fonovic, Matej

    2015-01-15

    Gaseous nitriding is a prominent thermochemical surface treatment process which can improve various properties of metallic materials such as mechanical, tribological and/or corrosion properties. This process is predominantly performed by applying NH{sub 3}+H{sub 2} containing gas atmospheres serving as the nitrogen donating medium at temperatures between 673 K and 873 K (400 C and 600 C). NH{sub 3} decomposes at the surface of the metallic specimen and nitrogen diffuses into the surface adjacent region of the specimen whereas hydrogen remains in the gas atmosphere. One of the most important parameters characterizing a gaseous nitriding process is the so-called nitriding potential (r{sub N}) which determines the chemical potential of nitrogen provided by the gas phase. The nitriding potential is defined as r{sub N} = p{sub NH{sub 3}}/p{sub H{sub 2}{sup 3/2}} where p{sub NH{sub 3}} and p{sub H{sub 2}} are the partial pressures of the NH{sub 3} and H{sub 2} in the nitriding atmosphere. In contrast with nitriding of α-Fe where the nitriding potential is usually in the range between 0.01 and 1 atm{sup -1/2}, nitriding of Ni and Ni-based alloys requires employing nitriding potentials higher than 100 atm{sup -1/2} and even up to ∞ (nitriding in pure NH{sub 3} atmosphere). This behavior is compatible with decreased thermodynamic stability of the 3d-metal nitrides with increasing atomic number. Depending on the nitriding conditions (temperature, nitriding potential and treatment time), different phases are formed at the surface of the Ni-based alloys. By applying very high nitriding potential, formation of hexagonal Ni{sub 3}N at the surface of the specimen (known as external nitriding) leads to the development of a compound layer, which may improve tribological properties. Underneath the Ni{sub 3}N compound layer, two possibilities exist: (i) alloying element precipitation within the nitrided zone (known as internal nitriding) and/or (ii) development of metastable and

  7. Investigation of the Precipitation Behavior in Aluminum Based Alloys

    KAUST Repository

    Khushaim, Muna S.

    2015-11-30

    The transportation industries are constantly striving to achieve minimum weight to cut fuel consumption and improve overall performance. Different innovative design strategies have been placed and directed toward weight saving combined with good mechanical behavior. Among different materials, aluminum-based alloys play a key role in modern engineering and are widely used in construction components because of their light weight and superior mechanical properties. Introduction of different nano-structure features can improve the service and the physical properties of such alloys. For intelligent microstructure design in the complex Al-based alloy, it is important to gain a deep physical understanding of the correlation between the microstructure and macroscopic properties, and thus atom probe tomography with its exceptional capabilities of spatially resolution and quantitative chemical analyses is presented as a sophisticated analytical tool to elucidate the underlying process of precipitation phenomena in aluminum alloys. A complete study examining the influence of common industrial heat treatment on the precipitation kinetics and phase transformations of complex aluminum alloy is performed. The qualitative evaluation results of the precipitation kinetics and phase transformation as functions of the heat treatment conditions are translated to engineer a complex aluminum alloy. The study demonstrates the ability to construct a robust microstructure with an excellent hardness behavior by applying a low-energy-consumption, cost-effective method. The proposed strategy to engineer complex aluminum alloys is based on both mechanical strategy and intelligent microstructural design. An intelligent microstructural design requires an investigation of the different strengthen phases, such as T1 (Al2CuLi), θ′(Al2Cu), β′(Al3Zr) and δ′(Al3Li). Therefore, the early stage of phase decomposition is examined in different binary Al-Li and Al-Cu alloys together with different

  8. Analysis of thermoelectric properties of high-temperature complex alloys of nickel-base, iron-base and cobalt-base groups

    Science.gov (United States)

    Holanda, R.

    1984-01-01

    The thermoelectric properties alloys of the nickel-base, iron-base, and cobalt-base groups containing from 1% to 25% 106 chromium were compared and correlated with the following material characteristics: atomic percent of the principle alloy constituent; ratio of concentration of two constituents; alloy physical property (electrical resistivity); alloy phase structure (percent precipitate or percent hardener content); alloy electronic structure (electron concentration). For solid-solution-type alloys the most consistent correlation was obtained with electron concentration, for precipitation-hardenable alloys of the nickel-base superalloy group, the thermoelectric potential correlated with hardener content in the alloy structure. For solid-solution-type alloys, no problems were found with thermoelectric stability to 1000; for precipitation-hardenable alloys, thermoelectric stability was dependent on phase stability. The effects of the compositional range of alloy constituents on temperature measurement uncertainty are discussed.

  9. BLENDED CALCIUM ALUMINATE-CALCIUM SULFATE CEMENT-BASED GROUT FOR P-REACTOR VESSEL IN-SITU DECOMMISSIONING

    Energy Technology Data Exchange (ETDEWEB)

    Langton, C.; Stefanko, D.

    2011-03-10

    The objective of this report is to document laboratory testing of blended calcium aluminate - calcium hemihydrate grouts for P-Reactor vessel in-situ decommissioning. Blended calcium aluminate - calcium hemihydrate cement-based grout was identified as candidate material for filling (physically stabilizing) the 105-P Reactor vessel (RV) because it is less alkaline than portland cement-based grout which has a pH greater than 12.4. In addition, blended calcium aluminate - calcium hemihydrate cement compositions can be formulated such that the primary cementitious phase is a stable crystalline material. A less alkaline material (pH {<=} 10.5) was desired to address a potential materials compatibility issue caused by corrosion of aluminum metal in highly alkaline environments such as that encountered in portland cement grouts [Wiersma, 2009a and b, Wiersma, 2010, and Serrato and Langton, 2010]. Information concerning access points into the P-Reactor vessel and amount of aluminum metal in the vessel is provided elsewhere [Griffin, 2010, Stefanko, 2009 and Wiersma, 2009 and 2010, Bobbitt, 2010, respectively]. Radiolysis calculations are also provided in a separate document [Reyes-Jimenez, 2010].

  10. Computational modelling of local calcium ions release from calcium phosphate-based scaffolds.

    Science.gov (United States)

    Manhas, Varun; Guyot, Yann; Kerckhofs, Greet; Chai, Yoke Chin; Geris, Liesbet

    2017-04-01

    A variety of natural or synthetic calcium phosphate (CaP)-based scaffolds are currently produced for dental and orthopaedic applications. These scaffolds have been shown to stimulate bone formation due to their biocompatibility, osteoconductivity and osteoinductivity. The release of the [Formula: see text] ions from these scaffolds is of great interest in light of the aforementioned properties. It can depend on a number of biophysicochemical phenomena such as dissolution, diffusion and degradation, which in turn depend on specific scaffold characteristics such as composition and morphology. Achieving an optimal release profile can be challenging when relying on traditional experimental work alone. Mathematical modelling can complement experimentation. In this study, the in vitro dissolution behaviour of four CaP-based scaffold types was investigated experimentally. Subsequently, a mechanistic finite element method model based on biophysicochemical phenomena and specific scaffold characteristics was developed to predict the experimentally observed behaviour. Before the model could be used for local [Formula: see text] ions release predictions, certain parameters such as dissolution constant ([Formula: see text]) and degradation constant ([Formula: see text]) for each type of scaffold were determined by calibrating the model to the in vitro dissolution data. The resulting model showed to yield release characteristics in satisfactory agreement with those observed experimentally. This suggests that the mathematical model can be used to investigate the local [Formula: see text] ions release from CaP-based scaffolds.

  11. CuZn Alloy- Based Electrocatalyst for CO2 Reduction

    KAUST Repository

    Alazmi, Amira

    2014-06-01

    ABSTRACT CuZn Alloy- Based Electrocatalyst for CO2 Reduction Amira Alazmi Carbon dioxide (CO2) is one of the major greenhouse gases and its emission is a significant threat to global economy and sustainability. Efficient CO2 conversion leads to utilization of CO2 as a carbon feedstock, but activating the most stable carbon-based molecule, CO2, is a challenging task. Electrochemical conversion of CO2 is considered to be the beneficial approach to generate carbon-containing fuels directly from CO2, especially when the electronic energy is derived from renewable energies, such as solar, wind, geo-thermal and tidal. To achieve this goal, the development of an efficient electrocatalyst for CO2 reduction is essential. In this thesis, studies on CuZn alloys with heat treatments at different temperatures have been evaluated as electrocatalysts for CO2 reduction. It was found that the catalytic activity of these electrodes was strongly dependent on the thermal oxidation temperature before their use for electrochemical measurements. The polycrystalline CuZn electrode without thermal treatment shows the Faradaic efficiency for CO formation of only 30% at applied potential ~−1.0 V vs. RHE with current density of ~−2.55 mA cm−2. In contrast, the reduction of oxide-based CuZn alloy electrode exhibits 65% Faradaic efficiency for CO at lower applied potential about −1.0 V vs. RHE with current density of −2.55 mA cm−2. Furthermore, stable activity was achieved over several hours of the reduction reaction at the modified electrodes. Based on electrokinetic studies, this improvement could be attributed to further stabilization of the CO2•− on the oxide-based Cu-Zn alloy surface.

  12. Dendritic growth and structure of undercooled nickel base alloys

    Science.gov (United States)

    Flemings, M. C.; Shiohara, Y.

    1988-01-01

    The principal objectives of this overall investigation are to: study means for obtaining high undercooling in levitation melted droplets, and study structures produced upon the solidification of these undercooled specimens. Thermal measurements are made of the undercooling, and of the rapid recalescence, to develop an understanding of the solidification mechanism. Comparison of results is made with the modeling studies. Characterization and metallographic work is done to gain an understanding of the relationship between rapid solidification variables and the structures so produced. In ground based work to date, solidification of undercooled Ni-25 wt percent Sn alloy was observed by high-speed cinematography and the results compared with optical temperature measurements. Also in ground based work, high-speed optical temperature measurements were made of the solidification behavior of levitated metal samples within a transparent glass medium. Two undercooled Ni-Sn alloys were examined. Measurements were carried out on samples at undercoolings up to 330 K. Microstructures of samples produced in ground based work were determined by optical metallography and by SEM, and microsegregation by electron microprobe measurements. A series of flight tests were planned to conduct experiments similar to the ground based experiments. The Space Shuttle Columbia carried an alloy undercooled experiment in the STS 61-C mission in January 1986. A sample of Ni-32.5 wt percent Sn eutectic was melted and solidified under microgravity conditions.

  13. Effect of calcium content on the microstructure, hardness and in-vitro corrosion behavior of biodegradable Mg-Ca binary alloy

    Directory of Open Access Journals (Sweden)

    Shervin Eslami Harandi

    2013-02-01

    Full Text Available Effect of calcium addition on microstructure, hardness value and corrosion behavior of five different Mg-xCa binary alloys (x = 0.7, 1, 2, 3, 4 wt. (% was investigated. Notable refinement in microstructure of the alloy occurred with increasing calcium content. In addition, more uniform distribution of Mg2Ca phase was observed in a-Mg matrix resulted in an increase in hardness value. The in-vitro corrosion examination using Kokubo simulated body fluid showed that the addition of calcium shifted the fluid pH value to a higher level similar to those found in pure commercial Mg. The high pH value amplified the formation and growth of bone-like apatite. Higher percentage of Ca resulted in needle-shaped growth of the apatite. Electrochemical measurements in the same solution revealed that increasing Ca content led to higher corrosion rates due to the formation of more cathodic Mg2Ca precipitate in the microstructure. The results therefore suggested that Mg-0.7Ca with the minimum amount of Mg2Ca is a good candidate for bio-implant applications.

  14. Effect of calcium content on the microstructure, hardness and in-vitro corrosion behavior of biodegradable Mg-Ca binary alloy

    Directory of Open Access Journals (Sweden)

    Shervin Eslami Harandi

    2012-01-01

    Full Text Available Effect of calcium addition on microstructure, hardness value and corrosion behavior of five different Mg-xCa binary alloys (x = 0.7, 1, 2, 3, 4 wt. (% was investigated. Notable refinement in microstructure of the alloy occurred with increasing calcium content. In addition, more uniform distribution of Mg2Ca phase was observed in a-Mg matrix resulted in an increase in hardness value. The in-vitro corrosion examination using Kokubo simulated body fluid showed that the addition of calcium shifted the fluid pH value to a higher level similar to those found in pure commercial Mg. The high pH value amplified the formation and growth of bone-like apatite. Higher percentage of Ca resulted in needle-shaped growth of the apatite. Electrochemical measurements in the same solution revealed that increasing Ca content led to higher corrosion rates due to the formation of more cathodic Mg2Ca precipitate in the microstructure. The results therefore suggested that Mg-0.7Ca with the minimum amount of Mg2Ca is a good candidate for bio-implant applications.

  15. Combined thermodynamic study of nickel-base alloys. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, C. R.; Meschter, P. J.

    1981-02-15

    Achievements during this period are the following: (1) initiation of a high-temperature study of the Ni-Ta system using the galvanic cell technique, (2) emf study of high-temperature thermodynamics in the Ni-Mo system, (3) measured heat capacity data on ordered and disordered Ni/sub 4/Mo, (4) heat capacities of Ni and disordered Ni/sub 3/Fe, and (5) computer correlation of thermodynamic and phase diagram data in binary Ni-base alloys. (MOW)

  16. The prospects of biodegradable magnesium-based alloys in osteosynthesis

    Directory of Open Access Journals (Sweden)

    V. N. Chorny

    2013-12-01

    various types of implants for osteosynthesis in traumatology and orthopedics. As the analysis of scientific papers over the past decade, the number of scientific articles devoted to the study of the properties of magnesium alloys and their effect on bone formation, as well as their use in osteosynthesis has grown significantly. Implants which are based on magnesium, may have several advantages over bioinert metal alloys, polymers, and bioceramics. They are not toxic, not carcinogenic, the mechanical properties of a structure close to the cortical bone, and may have osteoinductive and anti-bacterial action. Also, there is no need for a second surgical intervention. The main problems to be addressed, in our view, are as follows. 1. Need to examine the nature of -bone formation in the fracture in the presence of the implant based on magnesium alloy. 2. To examine the impact of products of magnesium degradation on the surrounding tissue and the body as a whole. 3. Loss of rigidity of the implant magnesium based alloy in the process of biodegradation.

  17. Iron-based alloys with corrosion resistance to oxygen-sulfur mixed gases

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, Krishnamurti (Naperville, IL)

    1992-01-01

    An iron-based alloy with improved performance with exposure to oxygen-sulfur mixed gases with the alloy containing about 9-30 wt. % Cr and a small amount of Nb and/or Zr implanted on the surface of the alloy to diffuse a depth into the surface portion, with the alloy exhibiting corrosion resistance to the corrosive gases without bulk addition of Nb and/or Zr and without heat treatment at temperatures of 1000.degree.-1100.degree. C.

  18. Role of alloying elements in adhesive transfer and friction of copper-base alloys

    Science.gov (United States)

    Buckley, D. H.

    1978-01-01

    Sliding friction experiments were conducted in a vacuum with binary-copper alloy riders sliding against a conventional bearing-steel surface with normal residual oxides present. The binary alloys contained 1 atomic percent of various alloying elements. Auger spectroscopy analysis was used to monitor the adhesive transfer of the copper alloys to the bearing-steel surface. A relation was found to exist between adhesive transfer and the reaction potential and free energy of formation of the alloying element in the copper. The more chemically active the element and the more stable its oxide, the greater was the adhesive transfer and wear of the copper alloy. Transfer occurred in all the alloys except copper-gold after relatively few (25) passes across the steel surface.

  19. High Frequency Vibration Based Fatigue Testing of Developmental Alloys

    Science.gov (United States)

    Holycross, Casey M.; Srinivasan, Raghavan; George, Tommy J.; Tamirisakandala, Seshacharyulu; Russ, Stephan M.

    Many fatigue test methods have been previously developed to rapidly evaluate fatigue behavior. This increased test speed can come at some expense, since these methods may require non-standard specimen geometry or increased facility and equipment capability. One such method, developed by George et al, involves a base-excited plate specimen driven into a high frequency bending resonant mode. This resonant mode is of sufficient frequency (typically 1200 to 1700 Hertz) to accumulate 107 cycles in a few hours. One of the main limitations of this test method is that fatigue cracking is almost certainly guaranteed to be surface initiated at regions of high stress. This brings into question the validity of the fatigue test results, as compared to more traditional uniaxial, smooth-bar testing, since high stresses are subjecting only a small volume to fatigue damage. This limitation also brings into question the suitability of this method to screen developmental alloys, should their initiation life be governed by subsurface flaws. However, if applicable, the rapid generation of fatigue data using this method would facilitate faster design iterations, identifying more quickly, material and manufacturing process deficiencies. The developmental alloy used in this study was a powder metallurgy boron-modified Ti-6Al-4V, a new alloy currently being considered for gas turbine engine fan blades. Plate specimens were subjected to fully reversed bending fatigue. Results are compared with existing data from commercially available Ti-6Al-4V using both vibration based and more traditional fatigue test methods.

  20. Effects of Alloying Elements on Room and High Temperature Tensile Properties of Al-Si Cu-Mg Base Alloys =

    Science.gov (United States)

    Alyaldin, Loay

    In recent years, aluminum and aluminum alloys have been widely used in automotive and aerospace industries. Among the most commonly used cast aluminum alloys are those belonging to the Al-Si system. Due to their mechanical properties, light weight, excellent castability and corrosion resistance, these alloys are primarily used in engineering and in automotive applications. The more aluminum is used in the production of a vehicle, the less the weight of the vehicle, and the less fuel it consumes, thereby reducing the amount of harmful emissions into the atmosphere. The principal alloying elements in Al-Si alloys, in addition to silicon, are magnesium and copper which, through the formation of Al2Cu and Mg2Si precipitates, improve the alloy strength via precipitation hardening following heat treatment. However, most Al-Si alloys are not suitable for high temperature applications because their tensile and fatigue strengths are not as high as desired in the temperature range 230-350°C, which are the temperatures that are often attained in automotive engine components under actual service conditions. The main challenge lies in the fact that the strength of heat-treatable cast aluminum alloys decreases at temperatures above 200°C. The strength of alloys under high temperature conditions is improved by obtaining a microstructure containing thermally stable and coarsening-resistant intermetallics, which may be achieved with the addition of Ni. Zr and Sc. Nickel leads to the formation of nickel aluminide Al3Ni and Al 9FeNi in the presence of iron, while zirconium forms Al3Zr. These intermetallics improve the high temperature strength of Al-Si alloys. Some interesting improvements have been achieved by modifying the composition of the base alloy with additions of Mn, resulting in an increase in strength and ductility at both room and high temperatures. Al-Si-Cu-Mg alloys such as the 354 (Al-9wt%Si-1.8wt%Cu-0.5wt%Mg) alloys show a greater response to heat treatment as a

  1. Effect of nitrogen on iron-manganese-based shape memory alloys

    Science.gov (United States)

    Ariapour, Azita

    Shape memory effect is due to a reversible martensitic transformation. The major drawback in case of Fe-Mn-based shape memory alloys is their inferior shape memory effect compared to Ni-Ti and Cu-based shape memory alloys and their low strength and corrosion resistance compared to steel alloys. It is known that by increasing the alloy strength the shape memory effect can be improved. Nitrogen in solid solution can increase the strength of steels to a greater extent than other major alloying elements. However, its effect on shape memory effect of Fe-Mn-based alloys is ambiguous. In this work first we investigated the effect of nitrogen addition in solid solution on both shape memory effect (SME) and strength of a Fe-Mn-Cr-Ni-Si shape memory alloy (SMA). It was found that interstitial nitrogen suppressed the shape memory effect in these alloys. As an example addition of 0.24 wt % nitrogen in solid solution to the alloy system suppressed the SME by ˜80% and increased the strength by 20%. A reduction of martensitic phase formation was found to be the dominant factor in suppression of the SME. This was related, experimentally and theoretically to stacking fault energy of the alloy as well as the driving force and friction force during the transformation. The second approach was doping the alloy with both 0.36 wt% of nitrogen and 0.36 wt% of niobium. Niobium has great affinity for nitrogen and thus NbN dispersed particles can be produced in the alloy following hot rolling. Then particles prevent growth of the alloy and increase the strength of the alloy due to reduced grain size, and precipitation hardening. The improvement of SME in this alloy compared to the interstitial containing alloys was due to the large removal of the nitrogen from solid solution. In case of all the alloys studied in this work, the presence of nitrogen in solid solution improved the corrosion resistance of the alloy. This suggests that nitrogen can replace nickel in the alloy. One of the

  2. Intracellular calcium spikes in rat suprachiasmatic nucleus neurons induced by BAPTA-based calcium dyes.

    Directory of Open Access Journals (Sweden)

    Jin Hee Hong

    Full Text Available BACKGROUND: Circadian rhythms in spontaneous action potential (AP firing frequencies and in cytosolic free calcium concentrations have been reported for mammalian circadian pacemaker neurons located within the hypothalamic suprachiasmatic nucleus (SCN. Also reported is the existence of "Ca(2+ spikes" (i.e., [Ca(2+](c transients having a bandwidth of 10 approximately 100 seconds in SCN neurons, but it is unclear if these SCN Ca(2+ spikes are related to the slow circadian rhythms. METHODOLOGY/PRINCIPAL FINDINGS: We addressed this issue based on a Ca(2+ indicator dye (fluo-4 and a protein Ca(2+ sensor (yellow cameleon. Using fluo-4 AM dye, we found spontaneous Ca(2+ spikes in 18% of rat SCN cells in acute brain slices, but the Ca(2+ spiking frequencies showed no day/night variation. We repeated the same experiments with rat (and mouse SCN slice cultures that expressed yellow cameleon genes for a number of different circadian phases and, surprisingly, spontaneous Ca(2+ spike was barely observed (<3%. When fluo-4 AM or BAPTA-AM was loaded in addition to the cameleon-expressing SCN cultures, however, the number of cells exhibiting Ca(2+ spikes was increased to 13 approximately 14%. CONCLUSIONS/SIGNIFICANCE: Despite our extensive set of experiments, no evidence of a circadian rhythm was found in the spontaneous Ca(2+ spiking activity of SCN. Furthermore, our study strongly suggests that the spontaneous Ca(2+ spiking activity is caused by the Ca(2+ chelating effect of the BAPTA-based fluo-4 dye. Therefore, this induced activity seems irrelevant to the intrinsic circadian rhythm of [Ca(2+](c in SCN neurons. The problems with BAPTA based dyes are widely known and our study provides a clear case for concern, in particular, for SCN Ca(2+ spikes. On the other hand, our study neither invalidates the use of these dyes as a whole, nor undermines the potential role of SCN Ca(2+ spikes in the function of SCN.

  3. Calculations of hydrogen diffusivity in Zr-based alloys: Influence of alloying elements and effect of stress

    Energy Technology Data Exchange (ETDEWEB)

    Yu, J. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Jiang, C. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Zhang, Y. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2017-06-01

    This report summarizes the progress on modeling hydrogen diffusivity in Zr-based alloys. The presence of hydrogen (H) can detrimentally affect the mechanical properties of many metals and alloys. To mitigate these detrimental effects requires fundamental understanding of the thermodynamics and kinetics governing H pickup and hydride formation. In this work, we focus on H diffusion in Zr-based alloys by studying the effects of alloying elements and stress, factors that have been shown to strongly affect H pickup and hydride formation in nuclear fuel claddings. A recently developed accelerated kinetic Monte Carlo method is used for the study. It is found that for the alloys considered here, H diffusivity depends weakly on composition, with negligible effect at high temperatures in the range of 600-1200 K. Therefore, the small variation in compositions of these alloys is likely not a major cause of the very different H pickup rates. In contrast, stress strongly affects H diffusivity. This effect needs to be considered for studying hydride formation and delayed hydride cracking.

  4. Metallic ion release from biocompatible cobalt-based alloy

    Directory of Open Access Journals (Sweden)

    Dimić Ivana D.

    2014-01-01

    Full Text Available Metallic biomaterials, which are mainly used for the damaged hard tissue replacements, are materials with high strength, excellent toughness and good wear resistance. The disadvantages of metals as implant materials are their susceptibility to corrosion, the elastic modulus mismatch between metals and human hard tissues, relatively high density and metallic ion release which can cause serious health problems. The aim of this study was to examine metallic ion release from Co-Cr-Mo alloy in artificial saliva. In that purpose, alloy samples were immersed into artificial saliva with different pH values (4.0, 5.5 and 7.5. After a certain immersion period (1, 3 and 6 weeks the concentrations of released ions were determined using Inductively Coupled Plasma - Mass Spectrophotometer (ICP-MS. The research findings were used in order to define the dependence between the concentration of released metallic ions, artificial saliva pH values and immersion time. The determined released metallic ions concentrations were compared with literature data in order to describe and better understand the phenomenon of metallic ion release from the biocompatible cobalt-based alloy. [Projekat Ministarstva nauke Republike Srbije, br. III 46010 i br. ON 174004

  5. Investigation of solidification dynamics of Zr-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kobold, Raphael; Herlach, Dieter [Institut fuer Materialphysik im Weltraum, Deutsches Zentrum fuer Luft- und Raumfahrt, 51170 Koeln (Germany); Ruhr-Universitaet Bochum, 44780 Bochum (Germany)

    2013-07-01

    In contrast to experiments with most undercooled binary alloys the velocity of dendritic growth of a Cu50Zr50 alloy does not increase monotonically with undercooling but passes through a maximum and then decreases. To study this behaviour we investigate Zr-based alloys such as CuZr, NiZr and NiZrAl with Zirconium concentrations ranging from 36 to 64 at.% including eutectic and intermetallic phases. We use electrostatic levitation technique to melt and undercool samples with a diameter of 2-3 mm under ultra-high-vacuum conditions. Containerless processing is an effective tool for undercooling metallic melts far below their equilibrium melting temperatures since heterogeneous nucleation on container walls is completely avoided. During crystallisation of the undercooled melt the heat of crystallisation is released. The rapid increase of the temperature at the solid-liquid interface makes the solidification front visible. The velocities of the solidification front are recorded by using a high-speed camera with a maximum rate of 50.000 frames per second and are analyzed with a software for optical ray tracing. Furthermore, we try to model the growth velocity vs. the undercooling temperature and perform sample EBSD analysis with a scanning electron microscope.

  6. In vitro element release and biological aspects of base?metal alloys for metal-ceramic applications

    OpenAIRE

    Holm, Charlotta; Morisbak, Else; Kalfoss, Torill; Dahl, Jon E.

    2015-01-01

    Abstract Objective: The aims of this study were to investigate the release of element from, and the biological response in vitro to, cobalt?chromium alloys and other base?metal alloys used for the fabrication of metal-ceramic restorations. Material and methods: Eighteen different alloys were investigated. Nine cobalt?chromium alloys, three nickel?chromium alloys, two cobalt?chromium?iron alloys, one palladium?silver alloy, one high-noble gold alloy, titanium grade II and one type III copper?a...

  7. My Experience with Ti-Ni-Based and Ti-Based Shape Memory Alloys

    Science.gov (United States)

    Miyazaki, Shuichi

    2017-10-01

    The present author has been studying shape memory alloys including Cu-Al-Ni, Ti-Ni-based, and Ni-free Ti-based alloys since 1979. This paper reviews the present author's research results for the latter two materials since 1981. The topics on the Ti-Ni-based alloys include the achievement of superelasticity in Ti-Ni alloys through understanding of the role of microstructures consisting of dislocations and precipitates, followed by the contribution to the development of application market of shape memory effect and superelasticity, characterization of the R-phase and monoclinic martensitic transformations, clarification of the basic characteristics of fatigue properties, development of sputter-deposited shape memory thin films and fabrication of prototypes of microactuators utilizing thin films, development of high temperature shape memory alloys, and so on. The topics of Ni-free Ti-based shape memory alloys include the characterization of the orthorhombic phase martensitic transformation and related shape memory effect and superelasticity, the effects of texture, omega phase and adding elements on the martensitic transformation and shape memory properties, clarification of the unique effects of oxygen addition to induce non-linear large elasticity, Invar effect and heating-induced martensitic transformation, and so on.

  8. My Experience with Ti-Ni-Based and Ti-Based Shape Memory Alloys

    Science.gov (United States)

    Miyazaki, Shuichi

    2017-12-01

    The present author has been studying shape memory alloys including Cu-Al-Ni, Ti-Ni-based, and Ni-free Ti-based alloys since 1979. This paper reviews the present author's research results for the latter two materials since 1981. The topics on the Ti-Ni-based alloys include the achievement of superelasticity in Ti-Ni alloys through understanding of the role of microstructures consisting of dislocations and precipitates, followed by the contribution to the development of application market of shape memory effect and superelasticity, characterization of the R-phase and monoclinic martensitic transformations, clarification of the basic characteristics of fatigue properties, development of sputter-deposited shape memory thin films and fabrication of prototypes of microactuators utilizing thin films, development of high temperature shape memory alloys, and so on. The topics of Ni-free Ti-based shape memory alloys include the characterization of the orthorhombic phase martensitic transformation and related shape memory effect and superelasticity, the effects of texture, omega phase and adding elements on the martensitic transformation and shape memory properties, clarification of the unique effects of oxygen addition to induce non-linear large elasticity, Invar effect and heating-induced martensitic transformation, and so on.

  9. Crystallization kinetics of Fe based amorphous alloy

    Science.gov (United States)

    Shanker Rao, T.; Lilly Shanker Rao, T.

    2015-02-01

    Differential Scanning Calorimetry(DSC) experimental data under non-isothermal conditions for Fe based Metglas 2605SA1 (wt% Fe=85-95, Si=5-10, B=1-5) metallic glass ribbons are reported and discussed. The DSC Scans performed at different heating rates showed two step crystallization processes and are interpreted in terms of different models like Kissinger, Ozawa, Boswell, Augis & Bennett and Gao & Wang. From the heating rate dependence of the onset temperature (To) and the crystallization peak temperature (Tp), the kinetic triplet, activation energy of crystallization (E), Avrami exponent (n) and the frequency factor (A) are determined. The determined E for peak I is 354.5 ± 2.5 kJ/mol and for the peak II is 348.2 ± 2.2 kJ/mol, respectively. The frequency factor for peak I is 1.1 × 1023sec-1 and for peak II is 6.1 × 1020sec-1.

  10. Modeling calcium wave based on anomalous subdiffusion of calcium sparks in cardiac myocytes.

    Directory of Open Access Journals (Sweden)

    Xi Chen

    Full Text Available Ca(2+ sparks and Ca(2+ waves play important roles in calcium release and calcium propagation during the excitation-contraction (EC coupling process in cardiac myocytes. Although the classical Fick's law is widely used to model Ca(2+ sparks and Ca(2+ waves in cardiac myocytes, it fails to reasonably explain the full-width at half maximum(FWHM paradox. However, the anomalous subdiffusion model successfully reproduces Ca(2+ sparks of experimental results. In this paper, in the light of anomalous subdiffusion of Ca(2+ sparks, we develop a mathematical model of calcium wave in cardiac myocytes by using stochastic Ca(2+ release of Ca(2+ release units (CRUs. Our model successfully reproduces calcium waves with physiological parameters. The results reveal how Ca(2+ concentration waves propagate from an initial firing of one CRU at a corner or in the middle of considered region, answer how large in magnitude of an anomalous Ca(2+ spark can induce a Ca(2+ wave. With physiological Ca(2+ currents (2pA through CRUs, it is shown that an initial firing of four adjacent CRUs can form a Ca(2+ wave. Furthermore, the phenomenon of calcium waves collision is also investigated.

  11. Effects of thermal aging on microstructures of low alloy steel-Ni base alloy dissimilar metal weld interfaces

    Science.gov (United States)

    Choi, Kyoung Joon; Kim, Jong Jin; Lee, Bong Ho; Bahn, Chi Bum; Kim, Ji Hyun

    2013-10-01

    In this study, the advanced instrumental analysis has been performed to investigate the effect of long-term thermal aging on the microstructural evolution in the fusion boundary region between weld metal and low alloy steel in dissimilar metal welds. A representative dissimilar weld mock-up made of Alloy 690-Alloy 152-A533 Gr. B was fabricated and aged at 450 °C for 2750 h. The micro- and nano-scale characterization were conducted mainly near in a weld root region by using optical microscopy, scanning electron microscopy, transmission electron microscopy, and three dimensional atom probe tomography. It was observed that the weld root was generally divided into several regions including dilution zone in the Ni-base alloy weld metal, fusion boundary, and heat-affected zone in the low alloy steel. A steep gradient was shown in the chemical composition profile across the interface between A533 Gr. B and Alloy 152. The precipitation of carbides was also observed along and near the fusion boundary of as-welded and aged dissimilar metal joints. It was also found that the precipitation of Cr carbides was enhanced by the thermal aging near the fusion boundary.

  12. Effects of thermal aging on microstructures of low alloy steel–Ni base alloy dissimilar metal weld interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kyoung Joon; Kim, Jong Jin [Interdisciplinary School of Green Energy, Ulsan National Institute of Science and Technology (UNIST), 100 Banyeon-ri, Eonyang-eup, Ulju-gun, Ulsan 689-798 (Korea, Republic of); Lee, Bong Ho [National Center for Nanomaterials Technology (NCNT), Pohang University of Science and Technology (POSTECH), 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 790-784 (Korea, Republic of); Bahn, Chi Bum [Argonne National Laboratory, 9700 S. Cass Ave, Lemont, IL 60439 (United States); Kim, Ji Hyun, E-mail: kimjh@unist.ac.kr [Interdisciplinary School of Green Energy, Ulsan National Institute of Science and Technology (UNIST), 100 Banyeon-ri, Eonyang-eup, Ulju-gun, Ulsan 689-798 (Korea, Republic of)

    2013-10-15

    In this study, the advanced instrumental analysis has been performed to investigate the effect of long-term thermal aging on the microstructural evolution in the fusion boundary region between weld metal and low alloy steel in dissimilar metal welds. A representative dissimilar weld mock-up made of Alloy 690-Alloy 152-A533 Gr. B was fabricated and aged at 450 °C for 2750 h. The micro- and nano-scale characterization were conducted mainly near in a weld root region by using optical microscopy, scanning electron microscopy, transmission electron microscopy, and three dimensional atom probe tomography. It was observed that the weld root was generally divided into several regions including dilution zone in the Ni-base alloy weld metal, fusion boundary, and heat-affected zone in the low alloy steel. A steep gradient was shown in the chemical composition profile across the interface between A533 Gr. B and Alloy 152. The precipitation of carbides was also observed along and near the fusion boundary of as-welded and aged dissimilar metal joints. It was also found that the precipitation of Cr carbides was enhanced by the thermal aging near the fusion boundary.

  13. A Novel Synthesis Method of Porous Calcium Silicate Hydrate Based on the Calcium Oxide/Polyethylene Glycol Composites

    Directory of Open Access Journals (Sweden)

    Wei Guan

    2013-01-01

    Full Text Available This paper proposed a novel method to prepare porous calcium silicate hydrate (CSH based on the calcium oxide/polyethylene glycol (CaO/PEG2000 composites as the calcium materials. The porosity formation mechanism was revealed via X-ray diffraction (XRD, field-emission scanning electron microscopy (FESEM, Brunauer-Emmett-Teller (BET, and Fourier transformed infrared spectroscopy (FT-IR. The reactivity of silica materials (SiO2 enhanced by increasing pH value. Ca2+ could not sustain release from CaO/PEG2000 and reacted with caused by silica to form CSH until the hydrothermal temperature reached to 170°C, avoiding the hardly dissolved intermediates formation efficiently. The as-prepared CSH, due to the large specific surface areas, exhibited excellent release capability of Ca2+ and OH−. This porous CSH has potential application in reducing the negative environmental effects of continual natural phosphate resource depletion.

  14. Brushing-induced surface roughness of nickel-, palladium-, and gold-based dental casting alloys.

    Science.gov (United States)

    Wataha, John C; Lockwood, Petra E; Messer, Regina L W; Lewis, Jill B; Mettenburg, Donald J

    2008-06-01

    Alloys with high nickel content have been increasingly used for dental prostheses. These alloys have excellent hardness, elastic modulus, and strength, yet have high corrosion rates when exposed to chemical or physical forces that are common intraorally. The purpose of the current study was to measure the susceptibility of several types of nickel-based alloys to brushing abrasion relative to gold- and palladium-based alloys. Au-Pt, Au-Pd, Pd-Ag, Ni-Cr, and Ni-Cr-Be dental alloys were brushed with a toothbrush (Oral-B Soft) and toothpaste (Ultrabrite) in a linear brushing machine, then the surface roughness was measured by profilometry (R(a), R(v), R(p)). Specimens (n=4) were brushed for 48 hours in a saline solution (pH 7). The effect of brushing was determined using 2-sided t tests (alpha=.05), and roughness among alloys postbrushing was compared using 1-way ANOVA with Tukey post hoc analyses (alpha=.05). All polished alloy surfaces (before brushing) had roughnesses of 1 microm (R(a)). Ni-Cr alloys without Be had a postbrushing surface roughness of 0.25 microm (R(a)). Postbrushing roughness of all other alloys ranged from 0.1-0.25 microm (R(a)). R(v) and R(p) values behaved similarly to R(a) values for all alloys. Although they have many excellent mechanical properties, Ni-Cr-Be alloys may be prone to degradation from brushing.

  15. Influence of S. mutans on base-metal dental casting alloy toxicity.

    Science.gov (United States)

    McGinley, E L; Dowling, A H; Moran, G P; Fleming, G J P

    2013-01-01

    We have highlighted that exposure of base-metal dental casting alloys to the acidogenic bacterium Streptococcus mutans significantly increases cellular toxicity following exposure to immortalized human TR146 oral keratinocytes. With Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), S. mutans-treated nickel-based (Ni-based) and cobalt-chromium-based (Co-Cr-based) dental casting alloys were shown to leach elevated levels of metal ions compared with untreated dental casting alloys. We targeted several biological parameters: cell morphology, viable cell counts, cell metabolic activity, cell toxicity, and inflammatory cytokine expression. S. mutans-treated dental casting alloys disrupted cell morphology, elicited significantly decreased viable cell counts (p casting alloys induced elevated levels of cellular toxicity compared with S. mutans-treated Co-Cr-based dental casting alloys. While our findings indicated that the exacerbated release of metal ions from S. mutans-treated base-metal dental casting alloys was the likely result of the pH reduction during S. mutans growth, the exact nature of mechanisms leading to accelerated dissolution of alloy-discs is not yet fully understood. Given the predominance of S. mutans oral carriage and the exacerbated cytotoxicity observed in TR146 cells following exposure to S. mutans-treated base-metal dental casting alloys, the implications for the long-term stability of base-metal dental restorations in the oral cavity are a cause for concern.

  16. Magnesium implant alloy with low levels of strontium and calcium: The third element effect and phase selection improve bio-corrosion resistance and mechanical performance

    Energy Technology Data Exchange (ETDEWEB)

    Bornapour, M., E-mail: mandana.bornapour@mail.mcgill.ca [Light Metals and Advanced Magnesium Materials, Mining and Materials Engineering, McGill University, Montreal, QC H3A 2B2 (Canada); Biointerface Lab, Mining and Materials Engineering, McGill University, Montreal, QC H3A 2B2 (Canada); Celikin, M. [Light Metals and Advanced Magnesium Materials, Mining and Materials Engineering, McGill University, Montreal, QC H3A 2B2 (Canada); Cerruti, M. [Biointerface Lab, Mining and Materials Engineering, McGill University, Montreal, QC H3A 2B2 (Canada); Pekguleryuz, M. [Light Metals and Advanced Magnesium Materials, Mining and Materials Engineering, McGill University, Montreal, QC H3A 2B2 (Canada)

    2014-02-01

    Low density, non-toxicity, biodegradability and mechanical properties similar to human tissues such as bone make magnesium (Mg) alloys attractive for biomedical applications ranging from bone to cardiovascular implants. The most important challenge that still prevents the widespread use of Mg implants is their rapid degradation rate. In this study we investigate the combined effect of calcium (Ca) and strontium (Sr) on the corrosion behavior of Mg via in vitro immersion and electrochemical tests in simulated body fluid (SBF), and analyze changes in mechanical properties. We show that the combined addition of 0.3 wt.% Sr and 0.4 wt.% Ca decreases the corrosion rate of Mg both in terms of mass loss and hydrogen evolution more effectively than the single addition of either alloying element. We investigate the microstructure of as-cast specimens and the morphology of the corrosion products using optical microscopy, scanning electron microscopy, electron probe micro-analysis, X-ray diffraction, and X-ray photoelectron spectroscopy. Tensile and three point bending tests reveal that the ternary alloy Mg–0.3Sr–0.3Ca has a good combination of mechanical properties and corrosion resistance with hydrogen evolution rates of 0.01 mL/cm{sup 2}/h in SBF. Higher concentrations of Sr and Ca alter the resulting microstructure leading to increased corrosion rates in SBF by promoting the micro-galvanic corrosion between the α-Mg matrix and intermetallic phases of Mg{sub 17}Sr{sub 2} and Mg{sub 2}Ca along the grain boundaries. These results indicate that the combined addition of optimal amounts of Ca and Sr is a promising approach to decrease the high degradation rate of Mg implants in physiological conditions, as well as attaining high ductility in the alloy. The better properties of the Mg–0.3Sr–0.3Ca alloy are related to the new intermetallic phases found in this sample. The optimum composition is attributed to the “third element effect”, as seen in the corrosion

  17. Method for producing La/Ce/MM/Y base alloys, resulting alloys and battery electrodes

    Science.gov (United States)

    Gschneidner, Jr., Karl A.; Schmidt, Frederick A.

    2016-12-20

    A carbothermic reduction method is provided for reducing a La-, Ce-, MM-, and/or Y-containing oxide in the presence of carbon and a source of a reactant element comprising Si, Ge, Sn, Pb, As, Sb, Bi, and/or P to form an intermediate alloy material including a majority of La, Ce, MM, and/or Y and a minor amount of the reactant element. The intermediate material is useful as a master alloy for in making negative electrode materials for a metal hydride battery, as hydrogen storage alloys, as master alloy additive for addition to a melt of commercial Mg and Al alloys, steels, cast irons, and superalloys; or in reducing Sm.sub.2O.sub.3 to Sm metal for use in Sm--Co permanent magnets.

  18. FUNCTIONAL COATINGS BY TERNARY COBALT BASED ALLOYS FOR THE AUTUMOBILE INDUSTRY

    Directory of Open Access Journals (Sweden)

    T. Nenastіna

    2015-07-01

    Full Text Available The environmentally friendly and resource-saving technologies for producing multifunctional coatings based on cobalt and silver alloys with refractory metals are proposed. The catalytic activity testing results of binary and ternary alloys based on cobalt in the carbon monoxide oxidation reaction in carbon dioxide were analyzed. It was revealed that there is on improvement of functional properties of galvanic alloys when the content of tungsten and molybdenum is within the range of 10–30 wt. %.

  19. Development of calcium phosphate based apatite from hen's eggshell

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Stoichiometric hydroxyapatite with Ca/P molar ratio, 1⋅67, was synthesized using hen's eggshell as calcium source and phosphoric acid by precipitation method. Conventional EDTA titration and gravimetric methods were adopted to estimate the amount of calcium and phosphorous, respectively. Fourier-transform.

  20. MODELING OF NI-CR-MO BASED ALLOYS: PART II - KINETICS

    Energy Technology Data Exchange (ETDEWEB)

    Turchi, P A; Kaufman, L; Liu, Z

    2006-07-07

    The CALPHAD approach is applied to kinetic studies of phase transformations and aging of prototypes of Ni-Cr-Mo-based alloys selected for waste disposal canisters in the Yucca Mountain Project (YMP). Based on a previous study on alloy stability for several candidate alloys, the thermodynamic driving forces together with a newly developed mobility database have been used to analyze diffusion-controlled transformations in these Ni-based alloys. Results on precipitation of the Ni{sub 2}Cr-ordered phase in Ni-Cr and Ni-Cr-Mo alloys, and of the complex P- and {delta}-phases in a surrogate of Alloy 22 are presented, and the output from the modeling are compared with experimental data on aging.

  1. Optimization of the aging regime of Al-based alloys

    Directory of Open Access Journals (Sweden)

    Ivanov Svetlana Lj.

    2012-01-01

    Full Text Available Successful simulation of problems and phenomena related to the changes of the alloys composition is possible by applying simplex plans. The concentration (simplex triangle application for the design of the optimal regime of Al-5wt%Cu-Pb-Bi alloy aging process is presented in this paper. The iso-lines of the given alloy’s mechanical properties in temperature-aging time coordinates were obtained by applying the mathematical models based of the given aging regimes, and the obtained results of changed properties. Regression polynomial of the fourth degree was used as the mathematical model, whereas the effect of the aging regime has been observed through the changes of tensile strength and contraction. Based on the obtained results, we have come to the conclusion that the simplex lattice method can be successfully applied to a great number of heat treatment aspects when with the increase of the temperature the duration time must be reduced, and vice versa (aging, annealing, homogenizing, etc..

  2. First principles study on Fe based ferromagnetic quaternary Heusler alloys

    Science.gov (United States)

    Amudhavalli, A.; Rajeswarapalanichamy, R.; Iyakutti, K.

    2017-11-01

    The study of stable half-metallic ferromagnetic materials is important from various fundamental and application points of view in condensed matter Physics. Structural phase stability, electronic structure, mechanical and magnetic properties of Fe-based quaternary Heusler alloys XX‧YZ (X = Co, Ni; X‧ = Fe; Y = Ti; Z = Si, Ge, As) for three different phases namely α, β and γ phases of LiMgPdSn crystal structure have been studied by density functional theory with generalized gradient approximation formulated by Perdew, Burke and Ernzerhof (GGA-PBE) and the Hubbard formalism (GGA-PBE + U). This work aims to identify the ferromagnetic and half-metallic properties of XX‧YZ (X = Co, Ni, X‧ = Fe; Y = Ti; Z = Si, Ge, As) quaternary Heusler alloys. The predicted phase stability shows that α-phase is found to be the lowest energy phase at ambient pressure. A pressure-induced structural phase transition is observed in CoFeTiSi, CoFeTiGe, CoFeTiAs, NiFeTiSi, NiFeTiGe and NiFeTiAs at the pressures of 151.6 GPa, 33.7 GPa, 76.4 GPa, 85.3 GPa, 87.7 GPa and 96.5 GPa respectively. The electronic structure reveals that these materials are half metals at normal pressure whereas metals at high pressure. The investigation of electronic structure and magnetic properties are performed to reveal the underlying mechanism of half metallicity. The spin polarized calculations concede that these quaternary Heusler compounds may exhibit the potential candidate in spintronics application. The magnetic moments for these quaternary Heusler alloys in all the three different phases (α, β and γ) are estimated.

  3. Efficacy of three methods for inserting calcium hydroxide-based paste in root canals

    OpenAIRE

    Galvão, Thales; Camargo, Bernardo; Armada, Luciana; Alves, Flávio

    2017-01-01

    Background To compare the quality of calcium hydroxide paste fillings performed by three different techniques. Material and Methods Sixty extracted maxillary central incisors, with previous root canal treatment, were decoronated and the gutta-percha was completely removed from the root canals. Subsequently, the canals were filled with a calcium hydroxide-based paste composed of calcium hydroxide, bismuth carbonate, and glycerin. The study samples were divided into the following three groups o...

  4. Combinatorial Density Functional Theory-Based Screening of Surface Alloys for the Oxygen Reduction Reaction

    DEFF Research Database (Denmark)

    Greeley, Jeffrey Philip; Nørskov, Jens Kehlet

    2009-01-01

    A density functional theory (DFT)-based, combinatorial search for improved oxygen reduction reaction (ORR) catalysts is presented. A descriptor-based approach to estimate the ORR activity of binary surface alloys, wherein alloying occurs only in the surface layer, is described, and rigorous......, potential-dependent computational tests of the stability of these alloys in aqueous, acidic environments are presented. These activity and stability criteria are applied to a database of DFT calculations on nearly 750 binary transition metal surface alloys; of these, many are predicted to be active...... for the ORR but, with few exceptions, they are found to be thermodynamically unstable in the acidic environments typical of low-temperature fuel cells. The results suggest that, absent other thermodynamic or kinetic mechanisms to stabilize the alloys, surface alloys are unlikely to serve as useful ORR...

  5. Evaluation of different finish line designs in base metal alloys

    Directory of Open Access Journals (Sweden)

    Aghandeh R

    1999-06-01

    Full Text Available This investigation was performed according to the widespread application of base metal alloys"nand few articles published about the marginal integrity of restorations fabricated by these metals."nThree standard dies of a maxillary first premolar were prepared with a flat shoulder finish line in buccal"naspect and chamfer in palatal. One of them left with no change. On the buccal aspect of the second and"nthird dies 135?and 1607 bevel were added respectively"nUsing dual wax technique, nine wax patterns were formed on each die and casting procedure of selected"nnon precious alloy was performed by centrifugal method. Marginal gaps of each copping seated on dies"nwere measured by scanning electron microscope (SEM with X500 magnification. Measurements were"ndone on three areas of marked dies on buccal aspect. Measurement son palatal aspect was done on"nmarked midpalatal point as control."nResults and statistical analysis showed no significant difference among marginal gaps in lingual aspect."nBut on the buccal aspect there were statistically significant differences among the groups (P<0.001. Flat"nshoulder had the best marginal integrity (mean 4 micron. Shoulder with 160' bevel had the most marginal"ngap (mean 26.5 micron and shoulder with 1357 bevel was between two other groups (mean 15.7 micron.

  6. Application of pyrolitic method of synthesis for preparation of calcium bismuthate based photocatalyst

    Science.gov (United States)

    Shtarev, Dmitry S.; Makarevich, Konstantin S.; Shtareva, Anna V.; Blokh, Artem I.; Syuy, Alexander V.

    2016-11-01

    The study describes use of pyrolytic synthesis method for preparation of visible light calcium bismuthate based photocatalyst. The advantage of the proposed method is that it allows obtaining single-phase, homogeneous samples with various types of crystal lattice and controlled defects. It is shown that it is possible to obtain crystalline calcium bismuthate with the same stoichiometry in the entire region of existence of the solid solution. Synthesized samples of calcium bismuthate have been characterized using the scanning electron microscopy and X-ray analysis. It was found that the scope and conditions of synthesis affect the degree of imperfection of both anionic and cationic sublattice of calcium bismuthate.

  7. Soft magnetic properties of rapidly quenched pig-iron-based alloys

    Science.gov (United States)

    Chakrabarti, P. K.; Mazaleyrat, F.; Varga, L. K.

    2003-01-01

    A family of rapidly quenched alloys based on pig iron (PI) having 6-10 at% additions (B, Ge, Ga,Al) has been found. In spite of small crystalline fraction, the best sample has the interesting values of resistivity, saturation polarization and magnetostriction of 129 μΩ cm , 1.59 T and 1.3 ppm, respectively. The AC power losses of these alloys were found comparable with those of the commercial glassy alloys.

  8. Monitoring the progression of calcium and protein solubilisation as affected by calcium chelators during small-scale manufacture of casein-based food matrices.

    Science.gov (United States)

    McIntyre, Irene; O'Sullivan, Michael; O'Riordan, Dolores

    2017-12-15

    Calcium and protein solubilisation during small-scale manufacture of semi-solid casein-based food matrices was investigated and found to be very different in the presence or absence of calcium chelating salts. Calcium concentrations in the dispersed phase increased and calcium-ion activity (ACa++) decreased during manufacture of the matrices containing calcium chelating salts; with ∼23% of total calcium solubilised by the end of manufacture. In the absence of calcium chelating salts, these concentrations were significantly lower at equivalent processing times and remained unchanged as did ACa++, throughout manufacture. The protein content of the dispersed phase was low (≤3% of total protein), but was significantly higher for matrices containing calcium chelating salts. This study elucidates the critical role of calcium chelating salts in modulating casein hydration and dispersion and gives an indication of the levels of soluble calcium and protein required to allow matrix formation during manufacture of casein-based food structures e.g. processed and analogue cheese. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Evaluation of Nb-base alloys for the divertor structure in fusion reactors

    Energy Technology Data Exchange (ETDEWEB)

    Purdy, I.M. [Argonne National Laboratory, Upton, IL (United States)

    1996-04-01

    Niobium-base alloys are candidate materials for the divertor structure in fusion reactors. For this application, an alloy should resist aqueous corrosion, hydrogen embrittlement, and radiation damage and should have high thermal conductivity and low thermal expansion. Results of corrosion and embrittlement screening tests of several binary and ternary Nb alloys in high-temperature water indicated the Mb-1Zr, Nb-5MO-1Zr, and Nb-5V-1Z4 (wt %) showed sufficient promise for further investigation. These alloys, together with pure Nb and Zircaloy-4 have been exposed to high purity water containing a low concentration of dissolved oxygen (<12 ppb) at 170, 230, and 300{degrees}C for up to {approx}3200 h. Weight-change data, microstructural observations, and qualitative mechanical-property evaluation reveal that Nb-5V-1Zr is the most promising alloy at higher temperatures. Below {approx}200{degrees}C, the alloys exhibit similiar corrosion behavior.

  10. Assessment of special stainless steels and nickel-base alloys for use under offshore conditions

    Energy Technology Data Exchange (ETDEWEB)

    Jasner, M.R. [Krupp VDM GmbH, Duisburg (Germany); Herda, W.R. [Krupp VDM GmbH, Werdohl (Germany)

    1994-12-31

    Major offshore installations are designed for a 25-years` life span and more. To predict the corrosion behavior of various alloys for such a long period results from accelerated laboratory tests have to be verified by suitable field tests. The results from laboratory tests and exposure to natural seawater show that nickel-based alloys such as alloy 59 (UNS N06059) and alloy 31 (UNS N08031) can be employed to most severe conditions. For general applications 6Mo stainless steels with 25% Ni such as alloy 926 (UNS N08926) may be used. If higher strength is required alloy 24 (18 Ni-24.5 Cr-6.2 Mn-4.3 Mo-0.6 Cu-0.45 Mn) is the preferred material.

  11. Elements loss analysis based on spectral diagnosis in laser-arc hybrid welding of aluminum alloy

    Science.gov (United States)

    Chen, Yong; Chen, Hui; Zhu, Minhao; Yang, Tao; Shen, Lin

    2017-07-01

    Aluminum alloy has been widely used in automobiles, high-speed trains, aerospace and many other fields. The loss of elements during welding process causes welding defects and affects the microstructure and properties of the joints. This paper discusses the correlation between welding process, spectral intensity and loss of elements in laser-arc hybrid welding of Al alloys. The results show that laser power and arc current have a significant impact on the spectral intensity and loss of elements. Compared with the base metal, the contents of alloying elements in the weld area are lower. The burning losses of alloy elements increase with the welding heat input.

  12. Development of Mg-Al-Zn based diecasting alloys for elevated temperature applications

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.M.; Park, B.K.; Jun, J.H.; Kim, K.T.; Jung, W.J. [Advanced Materials Development Center, Korea Inst. of Industrial Technology, Incheon (Korea); Shin, K. [Dept. of Metallurgy and Materials Science, Changwon National Univ., Changwon (Korea)

    2005-07-01

    Effort has been devoted to develop new heat resistant diecasting alloys based on Mg-Al-Zn system in this research. Small amounts of cerium-rich misch metal and antimony additions to AZ91 alloy could enhance the tensile strength at an elevated temperature while keeping the good castability. The increase of Zn content in Mg-8(wt%)Al-xZn-0.5RE-0.5Sb alloys, was observed to significantly increase the yield strength at 175 C although the castability such as fluidity and hot cracking resistance was slightly decreased. Intensive microstructural investigation on the new Mg-Al-Zn diecasting alloys was also carried out. (orig.)

  13. Fe-based magnetic shape memory alloy-sheet specimen

    Science.gov (United States)

    Kanada, Tsugunori; Enokizono, Masato

    1999-05-01

    We contrived a new composite functional alloy which is compatible for both magnetization and the shape memory effect (SME). A FeMnSiCr alloy, one of the shape memory alloys (SMA) has strong magnetization in addition to SME after heating in air. It is because the specimen is composed of a ferromagnetic iron oxide Fe 3O 4 (magnetite) surface layer, the inside being SMA. The measurements were carried out on a sheet specimen.

  14. Effects of heat treatment on mechanical and tribological properties of cobalt-base tribaloy alloys

    Science.gov (United States)

    Liu, Rong; Yao, Matthew X.; Patnaik, Prakash C.; Wu, Xijia

    2005-10-01

    Cobalt-base Tribaloy alloys are important wear-resistant materials, especially for high-temperature applications, because of the outstanding properties of the strengthened cobalt solid solution and the hard Laves intermetallic phase that make up the alloys. The Laves intermetallic phase is so abundant (35-70 vol.%) in these alloys that its presence governs all of the material properties. Heat treatment may alter the volume fraction, the size/shape, and the distribution of the Laves phase in the microstructures as well as the phase and structure of the cobalt solid solution, thus influencing the mechanical and tribological properties of the alloys. In this work, the effects of heat treatment on two cobalt-based Tribaloy alloys, T-400 and T-200, were studied. The former is a well-known Tribaloy alloy, and the latter is a newly developed one. These two alloys were heat treated in different conditions. The phases and microstructures of the alloys before and after the heat treatments were analyzed using x-ray and scanning electron microscopy. The mechanical and tribological properties of the alloys were investigated using a nano-indentation technique and a pin-on-disc tribometer, respectively.

  15. Shape Memory Alloy-Based Periodic Cellular Structures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I effort will develop and demonstrate an innovative shape memory alloy (SMA) periodic cellular structural technology. Periodic cellular structures...

  16. Emeraldine base as corrosion protective layer on aluminium alloy AA5182, effect of the surface microstructure

    DEFF Research Database (Denmark)

    Cecchetto, L; Ambat, Rajan; Davenport, A.J.

    2007-01-01

    AA5182 aluminium alloy cold rolled samples were coated by thin Wlms of emeraldine base (EB) obtained from a 5% solution in N-methylpyrrolidinone. Accelerated corrosion tests prove this coating very eVective for corrosion protection of aluminium alloys in neutral environment. This study underlines...

  17. On the formation of ultra-fine grained Fe-base alloys via phase transformations

    NARCIS (Netherlands)

    Chezan, AR; Craus, CB; Chechenin, NG; Vystavel, T; Niesen, L; De Hosson, JTM; Boerma, DO

    2004-01-01

    This paper concentrates on the formation of ultra-fine grained Fe-base alloys via phase transformations. In particular the manipulation of the microstructure of Fe-Ni-Ti and Fe-Ni-Cr alloys via phase cycling in the Fe-N system was investigated. Transitions between bcc (alpha-Fe), fee (gamma'-Fe4N)

  18. Thermal analysis of selected tin-based lead-free solder alloys

    DEFF Research Database (Denmark)

    Palcut, Marián; Sopoušek, J.; Trnková, L.

    2009-01-01

    The Sn-Ag-Cu alloys have favourable solderability and wetting properties and are, therefore, being considered as potential lead-free solder materials. In the present study, tin-based Sn-Ag-Cu and Sn-Ag-Cu-Bi alloys were studied in detail by a differential scanning calorimetry (DSC...

  19. Processing of New Materials by Additive Manufacturing: Iron-Based Alloys Containing Silver for Biomedical Applications

    Science.gov (United States)

    Niendorf, Thomas; Brenne, Florian; Hoyer, Peter; Schwarze, Dieter; Schaper, Mirko; Grothe, Richard; Wiesener, Markus; Grundmeier, Guido; Maier, Hans Jürgen

    2015-07-01

    In the biomedical sector, production of bioresorbable implants remains challenging due to improper dissolution rates or deficient strength of many candidate alloys. Promising materials for overcoming the prevalent drawbacks are iron-based alloys containing silver. However, due to immiscibility of iron and silver these alloys cannot be manufactured based on conventional processing routes. In this study, iron-manganese-silver alloys were for the first time synthesized by means of additive manufacturing. Based on combined mechanical, microscopic, and electrochemical studies, it is shown that silver particles well distributed in the matrix can be obtained, leading to cathodic sites in the composite material. Eventually, this results in an increased dissolution rate of the alloy. Stress-strain curves showed that the incorporation of silver barely affects the mechanical properties.

  20. Formation of alumina layers on iron-base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Peters, J.; Grabke, H.J.

    1984-09-01

    The formation of Al/sub 2/O/sub 3/-layers has been studied for ferritic alloys Fe-6Al-M and austenitic alloys Fe-27 Ni-4 Al-M where M-Ti, Zr, V, Nb, W, B, Si... (concentration in wt%). One or more alloying elements M had been added and in some cases carbon. The oxidation was performed at 1000/sup 0/C in H/sub 2/O-H/sub 2/ mixtures at PO/sub 2/ = 10/sup -19/ bar. After 1/2 h oxidation the oxide layers were investigated by X-ray structures analysis, scanning electron microscopy and Auger electron spectroscopy (AES). The alloy Fe-6Al and most doped alloys form badly adherent layers, however, on alloys with additions of 0.1 to 1% Ti, Zr, V or Y the oxide layers are fine-grained and well-adherent. The Ti-doped ferritic alloys showed very protective layers, which is caused by the formation of a Ti(C, O)-layer beneath the ..cap alpha..-Al/sub 2/O/sub 3/. The presence of the oxicarbide induces nucleation and improves the adherence of ..cap alpha..-Al/sub 2/O/sub 3/, according to epitaxial relations between ferrite and oxicarbide and between oxicarbide and alumina. The favourable influence of Ti and Zr on the Al/sub 2/O/sub 3/ formation is also effective on the austenitic alloys.

  1. Development and study of chemical vapor deposited tantalum base alloys

    Science.gov (United States)

    Meier, G. H.; Bryant, W. A.

    1976-01-01

    A technique for the chemical vapor deposition of alloys was developed. The process, termed pulsing, involves the periodic injection of reactant gases into a previously-evacuated reaction chamber where they blanket the substrate almost instantaneously. Formation of alternating layers of the alloy components and subsequent homogenization allows the formation of an alloy of uniform composition with the composition being determined by the duration and relative numbers of the various cycles. The technique has been utilized to produce dense alloys of uniform thickness and composition (Ta- 10 wt % W) by depositing alternating layers of Ta and W by the hydrogen reduction of TaCl5 and WCl6. A similar attempt to deposit a Ta - 8 wt % W - 2 wt% Hf alloy was unsuccessful because of the difficulty in reducing HfCl4 at temperatures below those at which gas phase nucleation of Ta and W occurred.

  2. Biodegradability and platelets adhesion assessment of magnesium-based alloys using a microfluidic system.

    Directory of Open Access Journals (Sweden)

    Lumei Liu

    Full Text Available Magnesium (Mg-based stents are extensively explored to alleviate atherosclerosis due to their biodegradability and relative hemocompatibility. To ensure the quality, safety and cost-efficacy of bioresorbable scaffolds and full utilization of the material tunability afforded by alloying, it is critical to access degradability and thrombosis potential of Mg-based alloys using improved in vitro models that mimic as closely as possible the in vivo microenvironment. In this study, we investigated biodegradation and initial thrombogenic behavior of Mg-based alloys at the interface between Mg alloys' surface and simulated physiological environment using a microfluidic system. The degradation properties of Mg-based alloys WE43, AZ31, ZWEK-L, and ZWEK-C were evaluated in complete culture medium and their thrombosis potentials in platelet rich plasma, respectively. The results show that 1 physiological shear stress increased the corrosion rate and decreased platelets adhesion rate as compared to static immersion; 2 secondary phases and impurities in material composition induced galvanic corrosion, resulting in higher corrosion resistance and platelet adhesion rate; 3 Mg-based alloys with higher corrosion rate showed higher platelets adhesion rate. We conclude that a microfluidic-based in vitro system allows evaluation of biodegradation behaviors and platelets responses of Mg-based alloys under specific shear stress, and degradability is related to platelets adhesion.

  3. Hydrogen sensor based on palladium-yttrium alloy nanosheet

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Boyi [Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, QLD 4111 (Australia); Zhu, Yong, E-mail: y.zhu@griffith.edu.au [Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, QLD 4111 (Australia); Chen, Youping; Song, Han; Huang, Pengcheng [School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074 (China); Dao, Dzung Viet [Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, QLD 4111 (Australia)

    2017-06-15

    This paper presents a hydrogen sensor based on palladium-yttrium (Pd-Y) alloy nanosheet. Zigzag-shaped Pd-Y nanosheet with a thickness of 19.3 nm was deposited on a quartz substrate by using an ultrahigh-vacuum magnetron sputtering system and shadow mask. The atomic ratio of palladium to yttrium in the nanosheet was 0.92/0.08. The fabrication process was simple and low-cost, and the sensor can be mass-produced. The experimental results show the sensor has a superior sensitivity, reversibility, and reproducibility. The resistive-based hydrogen detection mechanism in this research is much simpler and more compact compared to the optical-based detection method. - Highlights: • Pd-Y sensing element was fabricated using a magnetron sputtering system and shadow mask. • The Pd-Y compound consisted of 92% Pd and 8% Y. • The fabrication process was simple, low-cost, and mass-production compatible. • The sensor showed superior sensitivity, reversibility, and reproducibility to hydrogen gas. • The device is more compact than the optical-based counterpart.

  4. Strengthening mechanisms of indirect-extruded Mg–Sn based alloys at room temperature

    Directory of Open Access Journals (Sweden)

    Wei Li Cheng

    2014-12-01

    Full Text Available The strength of a material is dependent on how dislocations in its crystal lattice can be easily propagated. These dislocations create stress fields within the material depending on their intrinsic character. Generally, the following strengthening mechanisms are relevant in wrought magnesium materials tested at room temperature: fine-grain strengthening, precipitate strengthening and solid solution strengthening as well as texture strengthening. The indirect-extruded Mg–8Sn (T8 and Mg–8Sn–1Al–1Zn (TAZ811 alloys present superior tensile properties compared to the commercial AZ31 alloy extruded in the same condition. The contributions to the strengthen of Mg–Sn based alloys made by four strengthening mechanisms were calculated quantitatively based on the microstructure characteristics, physical characteristics, thermomechanical analysis and interactions of alloying elements using AZ31 alloy as benchmark.

  5. Mechanical alloying of Fe?Ni based nanostructured magnetic materials

    Science.gov (United States)

    Du, S. W.; Ramanujan, R. V.

    2005-04-01

    Alloys with the composition Fe 40Ni 38B 18Mo 4, Fe 49Ni 46Mo 5 and Fe 42Ni 40B 18 were processed from elemental powders by mechanical alloying and the microstructure was studied by differential scanning calorimetry (DSC), X-ray diffractometer (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. Nanocrystalline fcc solid solution was achieved as a result of mechanical alloying in all three alloy compositions and the grain size reduced to nanoscale but lattice strain was introduced. Molybdenum was found to affect the products of mechanical alloying, specifically, the Fe 3B phase formed in the Fe 42Ni 40B 18 alloy while no boride phase formed in the Fe 40Ni 38B 18Mo 4 alloy. SEM studies indicated that the presence of boron was found to make the milling process easier. Elemental mapping by SEM as well as XRD results showed that molybdenum does not dissolve easily in the Fe-Ni solid solution produced by milling. The DSC results suggested that an amorphous structure together with nanocrystals was obtained in the Fe 40Ni 38B 18Mo 4 and Fe 42Ni 40B 18 alloys. A two-stage crystallization process was found in the Fe 40Ni 38B 18Mo 4 and Fe 42Ni 40B 18 alloys, the presence of boron was found to make amorphization easier. TEM investigations were consistent with these XRD and DSC results. Heat-treated samples of the Fe 40Ni 38B 18Mo 4 and Fe 42Ni 40B 18 alloys milled for 100 h showed that molybdenum inhibited the grain growth. The saturation magnetization of the heat-treated Fe 40Ni 38B 18Mo 4 alloy milled for 100 h was stable, coercivity was reduced; on the other hand, the Ms of heat-treated Fe 42Ni 40B 18 alloy milled for 100 h decreased and the Hc increased. This difference in magnetic behavior is due to the alloying addition of molybdenum which affected the microstructural evolution during heat treatment, specifically by inhibition of the increase in grain size.

  6. Influence of calcium and magnesium based fertilizers on fungal ...

    African Journals Online (AJOL)

    Notwithstanding the important roles of calcium and magnesium ions in plant growth and development,the use of fertilizers containing them is not yet a common agricultural practice in Cameroon. Such fertilizers were applied on the soil and leaves of three most cultivated varieties of tomato in the Western Highlands of ...

  7. influence of calcium and magnesium based fertilizers on fungal

    African Journals Online (AJOL)

    PUBLICATIONS1

    Magnesium that activates many dehy- drogenases and phosphate transfer enzymes. (Öpik and Rolfe, 2005) may stimulate the ef- fects of calcium and/or ABA on fruit yield since ABA regulates fruit maturation, seed stor- age reserve accumulation and induces protein synthesis in seeds (Davies, 2007; Taiz and. Zeiger, 2006).

  8. Amorphous Calcium Carbonate Based-Microparticles for Peptide Pulmonary Delivery.

    Science.gov (United States)

    Tewes, Frederic; Gobbo, Oliviero L; Ehrhardt, Carsten; Healy, Anne Marie

    2016-01-20

    Amorphous calcium carbonate (ACC) is known to interact with proteins, for example, in biogenic ACC, to form stable amorphous phases. The control of amorphous/crystalline and inorganic/organic ratios in inhalable calcium carbonate microparticles may enable particle properties to be adapted to suit the requirements of dry powders for pulmonary delivery by oral inhalation. For example, an amorphous phase can immobilize and stabilize polypeptides in their native structure and amorphous and crystalline phases have different mechanical properties. Therefore, inhalable composite microparticles made of inorganic (i.e., calcium carbonate and calcium formate) and organic (i.e., hyaluronan (HA)) amorphous and crystalline phases were investigated for peptide and protein pulmonary aerosol delivery. The crystalline/amorphous ratio and polymorphic form of the inorganic component was altered by changing the microparticle drying rate and by changing the ammonium carbonate and HA initial concentration. The bioactivity of the model peptide, salmon calcitonin (sCT), coprocessed with alpha-1-antitrypsin (AAT), a model protein with peptidase inhibitor activity, was maintained during processing and the microparticles had excellent aerodynamic properties, making them suitable for pulmonary aerosol delivery. The bioavailability of sCT after aerosol delivery as sCT and AAT-loaded composite microparticles to rats was 4-times higher than that of sCT solution.

  9. influence of calcium and magnesium based fertilizers on fungal

    African Journals Online (AJOL)

    PUBLICATIONS1

    ABSTRACT. Notwithstanding the important roles of calcium and magnesium ions in plant growth and devel- opment, the use of fertilizers containing them is not yet a common agricultural practice in Cam- eroon. Such fertilizers were applied on the soil and leaves of three most cultivated varieties of tomato in the Western ...

  10. Durability studies on the high calcium flyash based GPC

    African Journals Online (AJOL)

    The sustainable development in the geopolymers is best used by the development of GPC. The durability ... Better microstructure for geopolymer pastes and mortars made of HCFA at mass ratios ..... Cheema D.S., 2012, Low calcium flyash geopolymer concrete –A promising sustainable alternative for rigid concrete road.

  11. Experimental research on combustion fluorine retention using calcium-based sorbets during coal combustion (I)

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Qing-jie; Lin, Zhi-yan; Liu, Jian-zhong; Wu, Xian; Zhou, Jun-hu; Cen, Ke-fa [Liaoning Technical University, Fuxin (China). College of Resource and Environment Engineering

    2008-06-15

    In order to provide experimental guide to commercial use of fluorine pollution control during coal combustion, with fluorine pollution control during coal combustion in mind, this paper proposed the theory of combustion fluorine retention technology. Feasibility of fluorine retention reaction with calcium-based fluorine retention agent was analyzed through thermodynamic calculation during coal combustion. By simulating the restraining and retention effects and influential factors of calcium-based sorbets on vaporized fluoride during experimental combustion using fixed bed tube furnace, the paper systematically explored the influential law of such factors as combustion temperature, retention time, and added quantities of calcium-based sorbets on effects of fluorine retention. The research result shows that adding calcium-based fluorine retention agent in coal combustion has double effects of fluorine retention and sulfur retention, it lays an experimental foundation for commercial test of combustion fluorine retention. 7 refs., 2 figs., 4 tabs.

  12. Effect of acute acid loading on acid-base and calcium metabolism

    DEFF Research Database (Denmark)

    Osther, Palle J

    2006-01-01

    OBJECTIVE: To investigate the acid-base and calcium metabolic responses to acute non-carbonic acid loading in idiopathic calcium stone-formers and healthy males using a quantitative organ physiological approach. MATERIAL AND METHODS: Five-h ammonium chloride loading studies were performed in 12...... male recurrent idiopathic calcium stone-formers and 12 matched healthy men using a randomized, placebo-controlled, cross-over design. Arterialized capillary blood, serum and urine were collected hourly for measurement of electrolytes, ionized calcium, magnesium, phosphate, parathyroid hormone and acid-base...... status. Concentrations of non-metabolizable base (NB) and acid (NA) were calculated from measured concentrations of non-metabolizable ions. RESULTS: The extracellular acid-base status in the stone-formers during basal conditions and acid loading was comparable to the levels in the healthy controls...

  13. Calcium-Sensitive MRI Contrast Agents Based on Superparamagnetic Iron Oxide Nanoparticles and Calmodulin

    National Research Council Canada - National Science Library

    Tatjana Atanasijevic; Maxim Shusteff; Peter Fam; Alan Jasanoff

    2006-01-01

    We describe a family of calcium indicators for magnetic resonance imaging (MRI), formed by combining a powerful iron oxide nanoparticle-based contrast mechanism with the versatile calciumsensing protein calmodulin and its targets...

  14. Dynamic precipitation of second phase under deformed condition in Mg-Nd based alloy

    Science.gov (United States)

    Dendge, Nilesh Bajirao

    Magnesium alloys are the lightweight structural materials with high strength to weigh ratio that permits their application in fuel economy sensitive automobile industries. Among the several flavors of of Mg-alloys, precipitation hardenable Mg-rare earth (RE) based alloys have shown good potential due to their favorable creep resistance within a wide window of operating temperatures ranging from 150°C to 300°C. A key aspect of Mg-RE alloys is the presence of precipitate phases that leads to strengthening of such alloys. Several notable works, in literature, have been done to examine the formation of such precipitate phases. However, there are very few studies that evaluated the effect stress induced deformation on the precipitation in Mg-RE alloys. Therefore, the objective of this work is to examine influence of deformation on the precipitation of Mg-Nd based alloys. To address this problem, precipitation in two Mg-Nd based alloys, subjected to two different deformation conditions, and was examined via transmission electron microscopy (TEM) and atom probe tomography (APT). In first deformation condition, Md-2.6wt%Nd alloy was subjected to creep deformation (90MPa / 177ºC) to failure. Effect of stress-induced deformation was examined by comparing and contrasting with precipitation in non-creep tested specimens subjected to isothermal annealing (at 177ºC). In second condition, Mg-4.0Y-3.0Nd-0.5Zr (wt %) or WE43 alloy (with comparable Nd content as model Mg-Nd system) was subjected to hot rolling deformation at a sub-solvus temperature.

  15. Selective thermal transformation of old computer printed circuit boards to Cu-Sn based alloy.

    Science.gov (United States)

    Shokri, Ali; Pahlevani, Farshid; Cole, Ivan; Sahajwalla, Veena

    2017-09-01

    This study investigates, verifies and determines the optimal parameters for the selective thermal transformation of problematic electronic waste (e-waste) to produce value-added copper-tin (Cu-Sn) based alloys; thereby demonstrating a novel new pathway for the cost-effective recovery of resources from one of the world's fastest growing and most challenging waste streams. Using outdated computer printed circuit boards (PCBs), a ubiquitous component of e-waste, we investigated transformations across a range of temperatures and time frames. Results indicate a two-step heat treatment process, using a low temperature step followed by a high temperature step, can be used to produce and separate off, first, a lead (Pb) based alloy and, subsequently, a Cu-Sn based alloy. We also found a single-step heat treatment process at a moderate temperature of 900 °C can be used to directly transform old PCBs to produce a Cu-Sn based alloy, while capturing the Pb and antimony (Sb) as alloying elements to prevent the emission of these low melting point elements. These results demonstrate old computer PCBs, large volumes of which are already within global waste stockpiles, can be considered a potential source of value-added metal alloys, opening up a new opportunity for utilizing e-waste to produce metal alloys in local micro-factories. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Study of the performance of Ti-Zr based hydrogen storage alloys

    Science.gov (United States)

    Chuang, H. J.; Chan, S. L. I.

    The P-C-I and charging-discharging properties of three Ti-Zr based alloys have been studied. Ni substitution for Mn and Cr in the alloy was found to increase the plateau pressure of the P-C-I curve. In addition, the partial substitution of Cr by V greatly improved the discharge capacity. However, the six-element alloy, Ti 0.5Zr 0.5V 0.2Mn 0.7Cr 0.5Ni 0.6, degraded rapidly in the gas-solid reaction. Hydrogen contents in the alloy under low pressure were increased during hydrogen absorption-desorption cycling. Annealing at 1050°C for 4 h before the P-C-I experiment helped in releasing the retained hydrogen under low pressure. Only a slightly flattened P-C-I slope was obtained for the annealed alloy. Microstructures of the as-cast and annealed alloys were examined and related to the above results. Alloy powder was poisoned after 2-month storage in air, which resulted in the deterioration of discharge capacity. Surface pretreatment on alloy powders by HCl-HF solution decreased the activation time of charge-discharge reaction.

  17. The Importance of Rare-Earth Additions in Zr-Based AB2 Metal Hydride Alloys

    Directory of Open Access Journals (Sweden)

    Kwo-Hsiung Young

    2016-07-01

    Full Text Available Effects of substitutions of rare earth (RE elements (Y, La, Ce, and Nd to the Zr-based AB2 multi-phase metal hydride (MH alloys on the structure, gaseous phase hydrogen storage (H-storage, and electrochemical properties were studied and compared. Solubilities of the RE atoms in the main Laves phases (C14 and C15 are very low, and therefore the main contributions of the RE additives are through the formation of the RENi phase and change in TiNi phase abundance. Both the RENi and TiNi phases are found to facilitate the bulk diffusion of hydrogen but impede the surface reaction. The former is very effective in improving the activation behaviors. −40 °C performances of the Ce-doped alloys are slightly better than the Nd-doped alloys but not as good as those of the La-doped alloys, which gained the improvement through a different mechanism. While the improvement in ultra-low-temperature performance of the Ce-containing alloys can be associated with a larger amount of metallic Ni-clusters embedded in the surface oxide, the improvement in the La-containing alloys originates from the clean alloy/oxide interface as shown in an earlier transmission electron microscopy study. Overall, the substitution of 1 at% Ce to partially replace Zr gives the best electrochemical performances (capacity, rate, and activation and is recommended for all the AB2 MH alloys for electrochemical applications.

  18. Welding and mechanical properties of cast FAPY (Fe-16 at. % Al-based) alloy slabs

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.; Goodwin, G.M.; Alexander, D.J.; Howell, C.R.

    1995-08-01

    The low-aluminum-content iron-aluminum program deals with the development of a Fe-Al alloy with aluminum content such as a produce the minimum environmental effect at room temperature. The FAPY is an Fe-16 at. % Al-based alloy developed at the Oak Ridge National Laboratory as the highest aluminum-containing alloy with essentially no environmental effect. The chemical composition for FAPY in weight percent is: aluminum = 8.46, chromium = 5.50, zirconium = 0.20, carbon = 0.03, molybdenum = 2.00, yttrium = 0.10, and iron = 83.71. The cast ingots of the alloy can be hot worked by extrusion, forging, and rolling processes. The hot- worked cast structure can be cold worked with intermediate anneals at 800{degrees}C. Typical room-temperature ductility of the fine-grained wrought structure is 20 to 25% for this alloy. In contrast to the wrought structure, the cast ductility at room temperature is approximately 1% with a transition temperature of approximately 100 to 150{degrees}C, above which ductility values exceed 20%. The alloy has been melted and processed into bar, sheet, and foil. The alloy has also been cast into slabs, step-blocks of varying thicknesses, and shapes. The purpose of this section is to describe the welding response of cast slabs of three different thicknesses of FAPY alloy. Tensile, creep, and Charpy-impact data of the welded plates are also presented.

  19. Alloy catalysts for fuel cell-based alcohol sensors

    Science.gov (United States)

    Ghavidel, Mohammadreza Zamanzad

    Direct ethanol fuel cells (DEFCs) are attractive from both economic and environmental standpoints for generating renewable energy and powering vehicles and portable electronic devices. There is a great interest recently in developing DEFC systems. The cost and performance of the DEFCs are mainly controlled by the Pt-base catalysts used at each electrode. In addition to energy conversion, DEFC technology is commonly employed in the fuel-cell based breath alcohol sensors (BrAS). BrAS is a device commonly used to measure blood alcohol concentration (BAC) and enforce drinking and driving laws. The BrAS is non-invasive and has a fast respond time. However, one of the most important drawback of the commercially available BrAS is the very high loading of Pt employed. One well-known and cost effective method to reduce the Pt loading is developing Pt-alloy catalysts. Recent studies have shown that Pt-transition metal alloy catalysts enhanced the electroactivity while decreasing the required loadings of the Pt catalysts. In this thesis, carbon supported Pt-Mn and Pt-Cu electrocatalysts were synthesized by different methods and the effects of heat treatment and structural modification on the ethanol oxidation reaction (EOR) activity, oxygen reduction reaction (ORR) activity and durability of these samples were thoroughly studied. Finally, the selected Pt-Mn and Pt-Cu samples with the highest EOR activity were examined in a prototype BrAS system and compared to the Pt/C and Pt 3Sn/C commercial electrocatalysts. Studies on the Pt-Mn catalysts produced with and without additives indicate that adding trisodium citrate (SC) to the impregnation solution improved the particle dispersion, decreased particle sizes and reduced the time required for heat treatment. Further studies show that the optimum weight ratio of SC to the metal loading in the impregnation solution was 2:1 and optimum results achieved at pH lower than 4. In addition, powder X-ray diffraction (XRD) analyses indicate

  20. Shape Memory Alloy-Based Periodic Cellular Structures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase II effort will continue to develop and demonstrate an innovative shape memory alloy (SMA) periodic cellular structural technology. Periodic cellular...

  1. Effect of alloying on elastic properties of ZrN based transition metal nitride alloys

    KAUST Repository

    Kanoun, Mohammed

    2014-09-01

    We report the effect of composition and metal sublattice substitutional element on the structural, elastic and electronic properties of ternary transition metal nitrides Zr1-xMxN with M=Al, Ti, Hf, V, Nb, W and Mo. The analysis of the elastic constants, bulk modulus, shear modulus, Young\\'s modulus, and Poisson\\'s ratio provides insights regarding the mechanical behavior of Zr1-xMxN. We predict that ternary alloys are more ductile compared to their parent binary compounds. The revealed trend in the mechanical behavior might help for experimentalists on the ability of tuning the mechanical properties during the alloying process by varying the concentration of the transition metal. © 2014 Elsevier B.V.

  2. Non-Gold Base Dental Casting Alloys. Volume 2. Porcelain-Fused-to-Metal Alloys.

    Science.gov (United States)

    1986-08-01

    aluminum - bronze (80-85% copper, 8-10% aluminum, 1-3% nickel, plus iron); beta -brass ." (60% copper and 40% zinc), and other lesser known entities. The...gypsum investment, plaster is the binder and silica is the refractory. Beauty-Cast and Cristobalite are examples of such investments. In general, gypsum... Cristobalite ) on heating. LIQUIDUS - The temperature above which an alloy is entirely molten. 4. LIQUIDUS RANGE - The temperature range from the

  3. FEATURES OF SPHEROIDIZING MODIFICATION OF HIGH-STRENGTH CAST IRON WITH MASTER ALLOYS BASED ON COPPER

    Directory of Open Access Journals (Sweden)

    A. S. Kalinichenko

    2016-01-01

    Full Text Available The increase of efficiency of modification process for ductile iron is topically, thereby increasing its mechanical and operational properties. For these purposes, in practice, various magnesium containing alloys are used, including «heavy» ones on the basis of Copper and Nickel. The analysis has shown that the application of bulk inoculating alloys based on copper basis were not effectively due to long dissolution period. From this point of view, the interest is high-speed casting, allowing the production of inoculating alloys in the form of strips – chips that are characterized by a low dissolution time and low piroeffekt. The aim of this work is to study the features of structure formation in nodular cast iron using different spheroidizing alloys based on copper. Studies have shown that the transition from the use of briquetted form alloys based on copper and magnesium to the «chips-inoculating alloys» allowed increasing the efficiency of the spheroidizing process. Further improvement in the quality of ductile iron can be achieved by the use in «chip-inoculating alloys» additives of nanosized yttrium oxide powder. 

  4. Microstructural characterisation of friction stir welding joints of mild steel to Ni-based alloy 625

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, J. [Brazilian Nanotechnology National Laboratory (LNNano), P.O. Box 6192, Campinas, SP (Brazil); University of Campinas (UNICAMP), Campinas, SP (Brazil); Ramirez, A.J., E-mail: ramirezlondono.1@osu.edu [Brazilian Nanotechnology National Laboratory (LNNano), P.O. Box 6192, Campinas, SP (Brazil); University of Campinas (UNICAMP), Campinas, SP (Brazil); Department of Materials Science and Engineering, The Ohio State University — OSU, Columbus, OH 43221 (United States)

    2015-12-15

    In this study, 6-mm-thick mild steel and Ni-based alloy 625 plates were friction stir welded using a tool rotational speed of 300 rpm and a travel speed of 100 mm·min{sup −1}. A microstructural characterisation of the dissimilar butt joint was performed using optical microscopy, scanning and transmission electron microscopy, and energy dispersive X-ray spectroscopy (XEDS). Six different weld zones were found. In the steel, the heat-affected zone (HAZ) was divided into three zones and was composed of ferrite, pearlite colonies with different morphologies, degenerated regions of pearlite and allotriomorphic and Widmanstätten ferrite. The stir zone (SZ) of the steel showed a coarse microstructure consisting of allotriomorphic and Widmanstätten ferrite, degenerate pearlite and MA constituents. In the Ni-based alloy 625, the thermo-mechanically affected zone (TMAZ) showed deformed grains and redistribution of precipitates. In the SZ, the high deformation and temperature produced a recrystallised microstructure, as well as fracture and redistribution of MC precipitates. The M{sub 23}C{sub 6} precipitates, present in the base material, were also redistributed in the stir zone of the Ni-based alloy. TMAZ in the steel and HAZ in the Ni-based alloy could not be identified. The main restorative mechanisms were discontinuous dynamic recrystallisation in the steel, and discontinuous and continuous dynamic recrystallisation in the Ni-based alloy. The interface region between the steel and the Ni-based alloy showed a fcc microstructure with NbC carbides and an average length of 2.0 μm. - Highlights: • Comprehensive microstructural characterisation of dissimilar joints of mild steel to Ni-based alloy • Friction stir welding of joints of mild steel to Ni-based alloy 625 produces sound welds. • The interface region showed deformed and recrystallised fcc grains with NbC carbides and a length of 2.0 μm.

  5. Preliminary study of raw material for calcium silicate/PVA coating on Ti-6Al-4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Azam, Farah ' Atiqah bt Abdul; Shamsudin, Roslinda, E-mail: linda@ukm.edu.my [School of Applied Physics, Faculty of Science and Technology Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan (Malaysia)

    2015-09-25

    Calcium silicate bioceramic was prepared from the rice husk and limestone resources using the sol gel method. The preparations of CaSiO{sub 3} formulation were differ from the previous study due CaO/SiO{sub 2} amount with 45:55 ratio. X-Ray Fluorescence analysis was carried out to clarify the amount of SiO{sub 2} and CaO content in the limestone and rice husk ash. The high amount of CaO was found in the limestone with the percentages of 97.22%, whereby 89% of SiO{sub 2} content of the rice husk ash. Several milling time were studied to obtain the optimized milling ti me and speed in progress to obtain nano size particle. The particle size analysis result confirms that increase in milling time does not certainly reduce the size of particle. The addition of 0.05% polyvinyl alcohol as a binder did not change the phases or composition of calcium silicates after examined by X-Ray diffraction analysis which make it suitable to be used as a binder for calcium silicate coating without changing the chemical structure.

  6. MACHINING OF NICKEL BASED ALLOYS USING DIFFERENT CEMENTED CARBIDE TOOLS

    Directory of Open Access Journals (Sweden)

    BASIM A. KHIDHIR

    2010-09-01

    Full Text Available This paper presents the results of experimental work in dry turning of nickel based alloys (Haynes – 276 using Deferent tool geometer of cemented carbide tools. The turning tests were conducted at three different cutting speeds (112, 152, 201and 269 m/min while feed rate and depth of cut were kept constant at 0.2 mm/rev and 1.5 mm, respectively. The tool holders used were SCLCR with insert CCMT-12 and CCLNR – M12-4 with insert CNGN-12. The influence of cutting speed, tool inserts type and workpiece material was investigated on the machined surface roughness. The worn parts of the cutting tools were also examined under scanning electron microscope (SEM. The results showed that cutting speed significantly affected the machined surface finish values in related with the tool insert geometry. Insert type CCMT-12 showed better surface finish for cutting speed to 201 m/min, while insert type CNGN-12 surface roughness increased dramatically with increasing of speed to a limit completely damage of insert geometer beyond 152 m/min.

  7. A Gradient-Based Constitutive Model for Shape Memory Alloys

    Science.gov (United States)

    Tabesh, Majid; Boyd, James; Lagoudas, Dimitris

    2017-06-01

    Constitutive models are necessary to design shape memory alloy (SMA) components at nano- and micro-scales in NEMS and MEMS. The behavior of small-scale SMA structures deviates from that of the bulk material. Unfortunately, this response cannot be modeled using conventional constitutive models which lack an intrinsic length scale. At small scales, size effects are often observed along with large gradients in the stress or strain. Therefore, a gradient-based thermodynamically consistent constitutive framework is established. Generalized surface and body forces are assumed to contribute to the free energy as work conjugates to the martensite volume fraction, transformation strain tensor, and their spatial gradients. The rates of evolution of these variables are obtained by invoking the principal of maximum dissipation after assuming a transformation surface, which is a differential equation in space. This approach is compared to the theories that use a configurational force (microforce) balance law. The developed constitutive model includes energetic and dissipative length scales that can be calibrated experimentally. Boundary value problems, including pure bending of SMA beams and simple torsion of SMA cylindrical bars, are solved to demonstrate the capabilities of this model. These problems contain the differential equation for the transformation surface as well as the equilibrium equation and are solved analytically and numerically. The simplest version of the model, containing only the additional gradient of martensite volume fraction, predicts a response with greater transformation hardening for smaller structures.

  8. Shape Memory Alloy (SMA)-Based Launch Lock

    Science.gov (United States)

    Badescu, Mircea; Bao, Xiaoqi; Bar-Cohen, Yoseph

    2014-01-01

    Most NASA missions require the use of a launch lock for securing moving components during the launch or securing the payload before release. A launch lock is a device used to prevent unwanted motion and secure the controlled components. The current launch locks are based on pyrotechnic, electro mechanically or NiTi driven pin pullers and they are mostly one time use mechanisms that are usually bulky and involve a relatively high mass. Generally, the use of piezoelectric actuation provides high precession nanometer accuracy but it relies on friction to generate displacement. During launch, the generated vibrations can release the normal force between the actuator components allowing shaft's free motion which could result in damage to the actuated structures or instruments. This problem is common to other linear actuators that consist of a ball screw mechanism. The authors are exploring the development of a novel launch lock mechanism that is activated by a shape memory alloy (SMA) material ring, a rigid element and an SMA ring holding flexure. The proposed design and analytical model will be described and discussed in this paper.

  9. Quality management of dispersion-strengthened beryllium-based composite alloy

    Directory of Open Access Journals (Sweden)

    Дмитро Миколайович Макаренко

    2016-05-01

    Full Text Available The article is devoted to investigation of the composition and properties of dispersion-strengthened beryllium-based composite alloy, used in various industries, including the aircraft manufacture aircraft. Analyzed the properties of these materials are analyzed to ensure their quality management. The mathematical relationship of dispersion strengthened beryllium-based composite alloy parameters from content of beryllium oxide and temperature are built

  10. Survey of BGFA Criteria for the Cu-Based Bulk Amorphous Alloys

    Directory of Open Access Journals (Sweden)

    D. Janovszky

    2011-01-01

    Full Text Available To verify the effect of composition on the bulk glass forming ability (BGFA of Cu-based alloys, properties have been collected from the literature (~100 papers, more than 200 alloys. Surveying the BGFA criteria published so far, it has been found that the atomic mismatch condition of Egami-Waseda is fulfilled for all the Cu-based BGFAs, the value being above 0,3. The Zhang Bangwei criterion could be applied for the binary Cu-based alloys. The Miracle and Senkov criteria do not necessarily apply for Cu based bulk amorphous alloys. The critical thickness versus =/(+ plot of Lu and Liu extrapolates to =0.36, somewhat higher than the 0.33 value found in other BGFA alloys. The Park and Kim parameter correlates rather poorly with the critical thickness for Cu based alloys. The Cheney and Vecchino parameter is a good indicator to find the best glass former if it is possible to calculate the exact liquids projection. In 2009 Xiu-lin and Pan defined a new parameter which correlates a bit better with the critical thickness. Based on this survey it is still very difficult to find one parameter in order to characterize the real GFA without an unrealized mechanism of crystallization.

  11. Porous Nb-Ti based alloy produced from plasma spheroidized powder

    Directory of Open Access Journals (Sweden)

    Qijun Li

    Full Text Available Spherical Nb-Ti based alloy powder was prepared by the combination of plasma spheroidization and mechanical alloying. Phase constituents, microstructure and surface state of the powder, and pore characteristics of the resulting porous alloy were investigated. The results show that the undissolved W and V in the mechanically alloyed powder is fully alloyed after spheroidization, and single β phase is achieved. Particle size of the spheroidized powder is in the range of 20–110 μm. With the decrease of particle size, a transformation from typical dendrite solidification structure to fine cell microstructure occurs. The surface of the spheroidized powder is coated by a layer of oxides consisting mainly of TiO2 and Nb2O5. Probabilities of sinter-neck formation and particle coalescence increases with increasing sintering temperature. Porous skeleton with relatively homogeneous pore distribution and open pore channel is formed after vacuum sintering at 1700 °C, and the porosity is 32%. The sintering kinetic analysis indicates that grain boundary diffusion is the primary mass transport mechanism during sintering process. Keywords: Powder metallurgy, Nb-Ti based alloy, Porous material, Mechanical alloying, Plasma spheroidizing, Solidification microstructure

  12. Design strategy for biodegradable Fe-based alloys for medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Schinhammer, Michael; Haenzi, Anja C.; Loeffler, Joerg F.; Uggowitzer, Peter J. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zuerich (Switzerland)

    2010-07-01

    Iron is a promising metallic element for bioabsorbable medical implants. The aim of this article is to describe a design strategy for the development of new biodegradable Fe-based alloys for temporary implant applications, in terms of both an enhanced degradation rate compared to pure iron, and suitable strength and ductility. The design strategy is based on electrochemical, microstructural and toxicological considerations. The influence of alloying elements on the electrochemical modification of the Fe matrix and the controlled formation of noble intermetallic phases is deployed. Manganese and palladium have been shown to be suitable alloying additions for this design strategy: Mn lowers the standard electrode potential, while Pd forms noble (Fe,Mn)Pd intermetallics acting as cathodic sites. We discuss the efficiency and the potential of the design approach, and evaluate the resulting characteristics of the new alloys. The newly developed Fe-Mn-Pd alloys reveal an increased degradation rate compared to pure iron. Additionally, the mechanical performance is shown to be adjustable not only by the choice of alloying elements but also by heat treatment procedures; high strength values >1400 MPa at ductility levels >10% can be achieved. Thus, the new alloys offer an attractive combination of electrochemical and mechanical characteristics considered suitable for biodegradable medical applications.

  13. Evaluation of Surface Roughness and Tensile Strength of Base Metal Alloys Used for Crown and Bridge on Recasting (Recycling).

    Science.gov (United States)

    Agrawal, Amit; Hashmi, Syed W; Rao, Yogesh; Garg, Akanksha

    2015-07-01

    Dental casting alloys play a prominent role in the restoration of the partial dentition. Casting alloys have to survive long term in the mouth and also have the combination of structure, molecules, wear resistance and biologic compatibility. According to ADA system casting alloys were divided into three groups (wt%); high noble, Noble and predominantly base metal alloys. To evaluate the mechanical properties such as tensile strength and surface roughness of the new and recast base metal (nickel-chromium) alloys. Recasting of the base metal alloys derived from sprue and button, to make it reusable has been done. A total of 200 test specimens were fabricated using specially fabricated jig of metal and divided into two groups- 100 specimens of new alloy and 100 specimens of recast alloys, which were tested for tensile strength on universal testing machine and surface roughness on surface roughness tester. Tensile strength of new alloy showed no statistically significant difference (p-value>0.05) from recast alloy whereas new alloy had statistically significant surface roughness (Maximum and Average surface roughness) difference (p-valuealloy. Within the limitations of the study it is concluded that the tensile strength will not be affected by recasting of nickel-chromium alloy whereas surface roughness increases markedly.

  14. ROLE OF GRAIN BOUNDARY CARBIDES IN CRACKING BEHAVIOR OF Ni BASE ALLOYS

    Directory of Open Access Journals (Sweden)

    SEONG SIK HWANG

    2013-02-01

    Full Text Available The primary water stress corrosion cracking (PWSCC of Alloy 600 in a PWR has been reported in the control rod drive mechanism (CRDM, pressurizer instrumentation, and the pressurizer heater sleeves. Recently, two cases of boric acid precipitation that indicated leaking of the primary cooling water were reported on the bottom head surface of steam generators (SG in Korea. The PWSCC resistance of Ni base alloys which have intergranular carbides is higher than those which have intragranular carbides. Conversely, in oxidized acidic solutions like sodium sulfate or sodium tetrathionate solutions, the Ni base alloys with a lot of carbides at the grain boundaries and shows less stress corrosion cracking (SCC resistance. The role of grain boundary carbides in SCC behavior of Ni base alloys was evaluated and effect of intergranular carbides on the SCC susceptibility were reviewed from the literature.

  15. Mechanical alloying of Fe-Ni based nanostructured magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Du, S.W. [School of Materials Engineering, Nanyang Technological University, B1k N4.1, Nanyang Ave., Singapore 639798 (Singapore); Ramanujan, R.V. [School of Materials Engineering, Nanyang Technological University, B1k N4.1, Nanyang Ave., Singapore 639798 (Singapore)]. E-mail: ramanujan@ntu.edu.sg

    2005-04-15

    Alloys with the composition Fe{sub 40}Ni{sub 38}B{sub 18}Mo{sub 4}, Fe{sub 49}Ni{sub 46}Mo{sub 5} and Fe{sub 42}Ni{sub 40}B{sub 18} were processed from elemental powders by mechanical alloying and the microstructure was studied by differential scanning calorimetry (DSC), X-ray diffractometer (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. Nanocrystalline fcc solid solution was achieved as a result of mechanical alloying in all three alloy compositions and the grain size reduced to nanoscale but lattice strain was introduced. Molybdenum was found to affect the products of mechanical alloying, specifically, the Fe{sub 3}B phase formed in the Fe{sub 42}Ni{sub 40}B{sub 18} alloy while no boride phase formed in the Fe{sub 40}Ni{sub 38}B{sub 18}Mo{sub 4} alloy. SEM studies indicated that the presence of boron was found to make the milling process easier. Elemental mapping by SEM as well as XRD results showed that molybdenum does not dissolve easily in the Fe-Ni solid solution produced by milling. The DSC results suggested that an amorphous structure together with nanocrystals was obtained in the Fe{sub 40}Ni{sub 38}B{sub 18}Mo{sub 4} and Fe{sub 42}Ni{sub 40}B{sub 18} alloys. A two-stage crystallization process was found in the Fe{sub 40}Ni{sub 38}B{sub 18}Mo{sub 4} and Fe{sub 42}Ni{sub 40}B{sub 18} alloys, the presence of boron was found to make amorphization easier. TEM investigations were consistent with these XRD and DSC results. Heat-treated samples of the Fe{sub 40}Ni{sub 38}B{sub 18}Mo{sub 4} and Fe{sub 42}Ni{sub 40}B{sub 18} alloys milled for 100 h showed that molybdenum inhibited the grain growth. The saturation magnetization of the heat-treated Fe{sub 40}Ni{sub 38}B{sub 18}Mo{sub 4} alloy milled for 100 h was stable, coercivity was reduced; on the other hand, the M {sub s} of heat-treated Fe{sub 42}Ni{sub 40}B{sub 18} alloy milled for 100 h decreased and the H {sub c} increased. This difference in magnetic

  16. Aging of a commercial Al-Cu-Si based alloy modified with germanium

    Energy Technology Data Exchange (ETDEWEB)

    Maksimovic, V.; Jovanovic, M.T. [Dept. of Materials Science, Vinca Inst. of Nuclear Sciences, Belgrade (Czechoslovakia); Tolley, A.; Radmilovic, V. [National Center for Electron Microscopy, LBLN Univ. of California, Berkeley (United States)

    2004-07-01

    The effect of small addition (0,7 wt.%) of Ge on precipitation during aging at 190 C of a modified commercial Al-Cu-Si based alloy has been studied. It was found that the maximum hardness in the alloy containing Ge was achieved three times faster than in the alloy without Ge. TEM results clearly demonstrate that the accelerated precipitation should be ascribed to a dense and fine distribution of Si-Ge particles serving as sites for heterogeneous precipitation of {theta}{sup ''} and {theta}' phases. Accelerated precipitation during aging was accompanied by increase in hardness. (orig.)

  17. Crystallographic Orientation Dependence of Corrosion Behavior of a Single Crystal Nickel-Based Alloy

    Science.gov (United States)

    Zhang, L. N.; Ojo, O. A.

    2018-01-01

    Crystallographic orientation dependence of corrosion behavior of a nickel-based single crystal alloy IN738 was studied. Potentiodynamic polarization and electrochemical impedance spectroscopy show that corrosion performance of the single crystal alloy varies with crystallographic orientation. The dependence of passivation behavior on crystallographic orientation is influenced by environmental concentration. Potentiostatic polarization, scanning probe microscopy, and X-ray photoelectron spectroscopy were performed to understand the variation in passivation of different crystallographic orientations. The crystallographic orientation dependence of corrosion performance of the alloy can be explained by the difference of passive films in terms of chemical compositions, compactness, and porosity properties, as well as surface roughness.

  18. Biocompatibility of new Ti-Nb-Ta base alloys.

    Science.gov (United States)

    Hussein, Abdelrahman H; Gepreel, Mohamed A-H; Gouda, Mohamed K; Hefnawy, Ahmad M; Kandil, Sherif H

    2016-04-01

    β-type titanium alloys are promising materials in the field of medical implants. The effect of β-phase stability on the mechanical properties, corrosion resistance and cytotoxicity of a newly designed β-type (Ti77Nb17Ta6) biocompatible alloys are studied. The β-phase stability was controlled by the addition of small quantities of Fe and O. X-ray diffraction and microstructural analysis showed that the addition of O and Fe stabilized the β-phase in the treated solution condition. The strength and hardness have increased with the increase in β-phase stability while ductility and Young's modulus have decreased. The potentio-dynamic polarization tests showed that the corrosion resistance of the new alloys is better than Ti-6Al-4V alloy by at least ten times. Neutral red uptake assay cytotoxicity test showed cell viability of at least 95%. The new alloys are promising candidates for biomedical applications due to their high mechanical properties, corrosion resistance, and reduced cytotoxicity. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Do Ca2+-adsorbing ceramics reduce the release of calcium ions from gypsum-based biomaterials?

    Science.gov (United States)

    Belcarz, Anna; Zalewska, Justyna; Pałka, Krzysztof; Hajnos, Mieczysław; Ginalska, Grazyna

    2015-02-01

    Bone implantable materials based on calcium sulfate dihydrate dissolve quickly in tissue liquids and release calcium ions at very high levels. This phenomenon induces temporary toxicity for osteoblasts, may cause local inflammation and delay the healing process. Reduction in the calcium ion release rate by gypsum could be therefore beneficial for the healing of gypsum-filled bone defects. The aim of this study concerned the potential use of calcium phosphate ceramics of various porosities for the reduction of high Ca(2+) ion release from gypsum-based materials. Highly porous ceramics failed to reduce the level of Ca(2+) ions released to the medium in a continuous flow system. However, it succeeded to shorten the period of high calcium level. It was not the phase composition but the high porosity of ceramics that was found crucial for both the shortening of the Ca(2+) release-related toxicity period and intensification of apatite deposition on the composite. Nonporous ceramics was completely ineffective for this purpose and did not show any ability to absorb calcium ions at a significant level. Moreover, according to our observations, complex studies imitating in vivo systems, rather than standard tests, are essential for the proper evaluation of implantable biomaterials. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Basic research for alloy design of Nb-base alloys as ultra high temperature structural materials; Chokoon kozoyo niobuki gokin no gokin sekkei no tame no kisoteki kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Miura, E. [Tohoku University, Sendai (Japan); Yoshimi, K.; Hanada, S. [Tohoku Univ., Sendai (Japan). Research Inst. for Iron, Steel and Other Metals

    1997-02-01

    This paper describes an influence of additional elements on the high temperature deformation behavior of Nb-base solid solution alloys. Highly concentrated solid solution single crystals of Nb-Ta and Nb-Mo alloys were prepared. Compression test and strain rate sudden change test were conducted in the vacuum at temperatures ranging from 77 to 1773 K, to determine the strain rate sensitivity index. Yield stress of the Nb-Ta alloy was similar to that of Nb alloy at temperatures over 0.3{times}T{sub M}, where T{sub M} is fusing point of Nb. While, the yield stress increased with increasing the impurity oxygen concentration at temperatures below 0.3{times}T{sub M}. The yield stress became much higher than that of Nb alloy. The strain rate sensitivity index showed positive values in the whole temperature range. On the other hand, the yield stress of Nb-Mo alloy was higher than that of Nb alloy in the whole temperature range, and increased with increasing the Mo concentration. The strain rate sensitivity index showed negative values at the temperature range from 0.3{times}T{sub M} to 0.4{times}T{sub M}. It was found that serration occurred often for Nb-40Mo alloys. 1 ref., 4 figs., 1 tab.

  1. Iron-based alloy and nitridation treatment for PEM fuel cell bipolar plates

    Science.gov (United States)

    Brady, Michael P [Oak Ridge, TN; Yang, Bing [Oak Ridge, TN; Maziasz, Philip J [Oak Ridge, TN

    2010-11-09

    A corrosion resistant electrically conductive component that can be used as a bipolar plate in a PEM fuel cell application is composed of an alloy substrate which has 10-30 wt. % Cr, 0.5 to 7 wt. % V, and base metal being Fe, and a continuous surface layer of chromium nitride and vanadium nitride essentially free of base metal. A oxide layer of chromium vanadium oxide can be disposed between the alloy substrate and the continuous surface nitride layer. A method to prepare the corrosion resistant electrically conductive component involves a two-step nitridization sequence by exposing the alloy to a oxygen containing gas at an elevated temperature, and subsequently exposing the alloy to an oxygen free nitrogen containing gas at an elevated temperature to yield a component where a continuous chromium nitride layer free of iron has formed at the surface.

  2. Sheet texture modification in magnesium-based alloys by selective rare earth alloying

    Energy Technology Data Exchange (ETDEWEB)

    Al-Samman, T., E-mail: al-samman@imm.rwth-aachen.de [Institut fuer Metallkunde und Metallphysik, RWTH Aachen University, D-52056 Aachen (Germany); Li, X. [Institut fuer Metallkunde und Metallphysik, RWTH Aachen University, D-52056 Aachen (Germany)

    2011-04-25

    Research highlights: {yields} Different RE elements gave distinct microstructures and imparted different properties. {yields} Gd demonstrated the highest potential to modify the sheet texture of rolled Mg. {yields} Gd yielded excellent mechanical properties despite a coarse-grained microstructure. {yields} RE alloying seems to promote the hard deformation mechanisms in Mg. {yields} Indications of PSN were found in the annealed microstructures of rolled sheets. - Abstract: The current study examines the influence of select rare earth elements; Gd, Nd, Ce, La and mischmetal (MM) on the sheet texture modification during warm rolling and annealing of a ZEK100 magnesium alloy, and the resulting formability and anisotropy during subsequent tensile testing at room temperature. It was found that all the investigated RE elements led to weak sheet textures and hence promoted enhanced ductility and reduced anisotropy over conventional Mg sheet. Gd was of a particular interest because it gave rise to a desired Mg sheet texture despite its coarsest grain size resulting in promising mechanical properties. It is suggested that solute related effects on the grain boundary migration and the relative strengths of different deformation mechanisms are responsible for altering the common concepts of recrystallization and grain growth during annealing, and the activation scenarios of slip and twinning during deformation.

  3. Corrosion Behavior of Amorphous Nickel-Base Alloys in a Boiling Concentrated Sodium Hydroxide Solution

    OpenAIRE

    Kazuo, SHIMAMURA; Kimikado, MIURA; Asahi, Kawashima; Katsuhiko, Asami; Koji, Hashimoto; Institute for Materials Research:Mitsui Engineering & Shipbuilding Co., Ltd.; Institute for Materials Research

    1988-01-01

    Polarization curves were measured in a boiling 50% NaOH solution, and the specimen surface was analyzed by X-ray photoelectron spectroscopy. A combined addition of chromium and molybdenum to amorphous nickel-phosphorus alloys significantly enhances the corrosion resistance. Addition of copper and lead are also effective in improving the corrosion resistance. The surface film formed on amorphous nickel-base alloys consists mainly of hydrated nickel oxyhydroxide. Chromium is concentrated in the...

  4. Nickel, cobalt and titanium-based alloys – from aircraft vehicles to medical applications - REVIEW

    OpenAIRE

    Milan Jovanović

    2016-01-01

    Since the introduction of nickel, cobalt and titanium-based alloys in the early 1950s, these materials in a relatively short time became backbone materials for the aerospace, energy, chemical industry and even medicine. The combination of excellent mechanical properties, corrosion resistance and bio-compatibility renders these alloys the best material choice for many critical applications. This review describes the results realized through the research in the Department of Materials Science i...

  5. Leaching characteristics of calcium-based compounds in MSWI Residues: From the viewpoint of clogging risk

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Yi [State Key Laboratory of Pollution Control & Resource Reuse, Tongji University, Shanghai 200092 (China); Institute of Waste Treatment and Reclamation, Tongji University, Shanghai 200092 (China); Zhang, Hua, E-mail: zhanghua_tj@tongji.edu.cn [State Key Laboratory of Pollution Control & Resource Reuse, Tongji University, Shanghai 200092 (China); Phoungthong, Khamphe [State Key Laboratory of Pollution Control & Resource Reuse, Tongji University, Shanghai 200092 (China); Institute of Waste Treatment and Reclamation, Tongji University, Shanghai 200092 (China); Shi, Dong-Xiao; Shen, Wen-Hui [Changzhou Domestic Waste Treatment Center, Changzhou 213000 (China); Shao, Li-Ming [Institute of Waste Treatment and Reclamation, Tongji University, Shanghai 200092 (China); Center for the Technology Research and Training on Household Waste in Small Towns & Rural Area, Ministry of Housing and Urban–Rural Development of PR China (MOHURD), Shanghai 200092 (China); He, Pin-Jing, E-mail: solidwaste@tongji.edu.cn [Institute of Waste Treatment and Reclamation, Tongji University, Shanghai 200092 (China); Center for the Technology Research and Training on Household Waste in Small Towns & Rural Area, Ministry of Housing and Urban–Rural Development of PR China (MOHURD), Shanghai 200092 (China)

    2015-08-15

    Highlights: • The leaching behavior of Ca-based compounds commonly in MSWI residues was studied. • pH is the crucial factor for calcium leaching process. • CaCO{sub 3} was the most sensitive to leaching temperature and Ca{sub 3}(PO{sub 4}){sub 2} was the least. • Ca leaching of MSWIBA and SAPCR attributed to CaCO{sub 3} and Ca{sub 3}(PO{sub 4}){sub 2} respectively. • Potential clogging ability of MSWI residues leachate in open air was calculated. - Abstract: Leachate collection system (LCS) clogging caused by calcium precipitation would be disadvantageous to landfill stability and operation. Meanwhile, calcium-based compounds are the main constituents in both municipal solid waste incineration bottom ash (MSWIBA) and stabilized air pollution control residues (SAPCR), which would increase the risk of LCS clogging once these calcium-rich residues were disposed in landfills. The leaching behaviors of calcium from the four compounds and municipal solid waste incineration (MSWI) residues were studied, and the influencing factors on leaching were discussed. The results showed that pH was the crucial factor in the calcium leaching process. CaCO{sub 3} and CaSiO{sub 3} began leaching when the leachate pH decreased to less than 7 and 10, respectively, while Ca{sub 3}(PO{sub 4}){sub 2} leached at pH < 12. CaSO{sub 4} could hardly dissolve in the experimental conditions. Moreover, the sequence of the leaching rate for the different calcium-based compounds is as follows: CaSiO{sub 3} > Ca{sub 3}(PO{sub 4}){sub 2} > CaCO{sub 3}. The calcium leaching from the MSWIBA and SAPCR separately started from pH < 7 and pH < 12, resulting from CaCO{sub 3} and Ca{sub 3}(PO{sub 4}){sub 2} leaching respectively, which was proven by the X-ray diffraction results. Based on the leaching characteristics of the different calcium compounds and the mineral phase of calcium in the incineration residues, simulated computation of their clogging potential was conducted, providing the

  6. Bond strength of resin cements to noble and base metal alloys with different surface treatments.

    Directory of Open Access Journals (Sweden)

    Farkhondeh Raeisosadat

    2014-10-01

    Full Text Available The bond strength of resin cements to metal alloys depends on the type of the metal, conditioning methods and the adhesive resins used. The purpose of this study was to evaluate the bond strength of resin cements to base and noble metal alloys after sand blasting or application of silano-pen.Cylinders of light cured Z 250 composite were cemented to "Degubond 4" (Au Pd and "Verabond" (Ni Cr alloys by either RelyX Unicem or Panavia F2, after sandblasting or treating the alloys with Silano-Pen. The shear bond strengths were evaluated. Data were analyzed by three-way ANOVA and t tests at a significance level of P<0.05.When the alloys were treated by Silano-Pen, RelyX Unicem showed a higher bond strength for Degubond 4 (P=0.021 and Verabond (P< 0.001. No significant difference was observed in the bond strength of Panavia F2 to the alloys after either of surface treatments, Degubond 4 (P=0.291 and Verabond (P=0.899. Panavia F2 showed a higher bond strength to sandblasted Verabond compared to RelyX Unicem (P=0.003. The bond strength of RelyX Unicem was significantly higher to Silano-Pen treated Verabond (P=0.011. The bond strength of the cements to sandblasted Degubond 4 showed no significant difference (P=0.59. RelyX Unicem had a higher bond strength to Silano-Pen treated Degubond 4 (P=0.035.The bond strength of resin cements to Verabond alloy was significantly higher than Degubond 4. RelyX Unicem had a higher bond strength to Silano-Pen treated alloys. Surface treatments of the alloys did not affect the bond strength of Panavia F2.

  7. Nickel-base alloy forgings for advanced high temperature power plants

    Energy Technology Data Exchange (ETDEWEB)

    Donth, B.; Diwo, A.; Blaes, N.; Bokelmann, D. [Saarschmiede GmbH Freiformschmiede, Voelklingen (Germany)

    2008-07-01

    The strong efforts to reduce the CO{sub 2} emissions lead to the demand for improved thermal efficiency of coal fired power plants. An increased thermal efficiency can be realised by higher steam temperatures and pressures in the boiler and the turbine. The European development aims for steam temperatures of 700 C which requires the development and use of new materials and also associated process technology for large components. Temperatures of 700 C and above are too high for the application of ferritic steels and therefore only Nickel-Base Alloys can fulfill the required material properties. In particular the Nickel-Base Alloy A617 is the most candidate alloy on which was focused the investigation and development in several German and European programs during the last 10 years. The goal is to verify and improve the attainable material properties and ultrasonic detectability of large Alloy 617 forgings for turbine rotors and boiler parts. For many years Saarschmiede has been manufacturing nickel and cobalt alloys and is participating the research programs by developing the manufacturing routes for large turbine rotor forgings up to a maximum diameter of 1000 mm as well as for forged tubes and valve parts for the boiler side. The experiences in manufacturing and testing of very large forgings made from nickel base alloys for 700 C steam power plants are reported. (orig.)

  8. Undercooling and demixing of copper-based alloys

    DEFF Research Database (Denmark)

    Kolbe, M.; Brillo, J.; Egry, I.

    2006-01-01

    Since the beginning of materials science research under microgravity conditions immiscible alloys have been an interesting subject. New possibilities to investigate such systems are offered by containerless processing techniques. Of particular interest is the ternary system Cu-Fe-Co, and its...

  9. Fracture behavior of nickel-based alloys in water

    Energy Technology Data Exchange (ETDEWEB)

    Mills, W.J.; Brown, C.M.

    1999-08-01

    The cracking resistance of Alloy 600, Alloy 690 and their welds, EN82H and EN52, was characterized by conducting J{sub IC} tests in air and hydrogenated water. All test materials displayed excellent toughness in air and high temperature water, but Alloy 690 and the two welds were severely embrittled in low temperature water. In 54 C water with 150 cc H{sub 2}/kg H{sub 2}O, J{sub IC} values were typically 70% to 95% lower than their air counterparts. The toughness degradation was associated with a fracture mechanism transition from microvoid coalescence to intergranular fracture. Comparison of the cracking response in water with that for hydrogen-precharged specimens tested in air demonstrated that susceptibility to low temperature cracking is due to hydrogen embrittlement of grain boundaries. The effects of water temperature, hydrogen content and loading rate on low temperature crack propagation were studied. In addition, testing of specimens containing natural weld defects and as-machined notches was performed to determine if low temperature cracking can initiate at these features. Unlike the other materials, Alloy 600 is not susceptible to low temperature cracking as the toughness in 54 C water remained high and a microvoid coalescence mechanism was operative in both air and water.

  10. Moessbauer spectroscopy of Fe-B based amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kreislerova, Y.; Zemcik, T. (Ceskoslovenska Akademie Ved, Brno. Ustav Fyzikalni Metalurgie)

    1984-01-01

    The influence of heat treatment on structure changes of amorphous alloy Fe/sub 83/B/sub 17/ was studied by /sup 57/Fe Moessbauer spectroscopy. At 613 K a change in the magnetization direction was detected and at 633 K the precipitation of ..cap alpha..-Fe quantitatively determined.

  11. The calcium fluoride effect on properties of cryolite melts feasible for low-temperature production of aluminum and its alloys

    Science.gov (United States)

    Tkacheva, O.; Dedyukhin, A.; Redkin, A.; Zaikov, Yu.

    2017-07-01

    The CaF2 effect on the liquidus temperature, electrical conductivity and alumina solubility in the potassium-sodium and potassium-lithium cryolite melts with cryolite ratio (CR = (nKF+nMF)/nAlF3, M = Li, Na) 1.3 was studied. The liquidus temperature in the quisi-binary system [KF-LiF-AlF3]-CaF2 changes with the same manner as in the [KF-NaF-AlF3]-CaF2. The electrical conductivity in the KF-NaF-AlF3-CaF2 melt decreases with increasing the CaF2 content, but it slightly raises with the first small addition of CaF2 into the KF-LiF-AlF3-CaF2 melts, enriched with KF, which was explained by the increased K+ ions mobility due to their relatively low ionic potential. The contribution of the Li+ cations in conductivity of the KF-LiF-AlF3-CaF2 electrolyte is not noteworthy. The Al2O3 solubility in the KF-NaF-AlF3 electrolyte rises with the increasing KF content, but the opposite tendency is observed in the cryolite mixtures containing CaF2. The insoluble compounds - KCaAl2F9 or KCaF3 - formed in the molten mixtures containing potassium and calcium ions endorse the increase of the liquidus temperature. The calcium fluoride effect on the side ledge formation in the electrolytic cell during low-temperature aluminum electrolysis is discussed.

  12. Description of the capacity degradation mechanism in LaNi{sub 5}-based alloy electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Spodaryk, Mariana, E-mail: poshtamary@ukr.net [Institute for Problems of Materials Science, NAS of Ukraine, 3, Krzhyzhanovsky Str., 03680 Kyiv-142 (Ukraine); Shcherbakova, Larisa; Sameljuk, Anatoly [Institute for Problems of Materials Science, NAS of Ukraine, 3, Krzhyzhanovsky Str., 03680 Kyiv-142 (Ukraine); Wichser, Adrian; Zakaznova-Herzog, Valentina; Holzer, Marco; Braem, Beat [EMPA Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf (Switzerland); Khyzhun, Oleg [Institute for Problems of Materials Science, NAS of Ukraine, 3, Krzhyzhanovsky Str., 03680 Kyiv-142 (Ukraine); Mauron, Philippe; Remhof, Arndt [EMPA Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf (Switzerland); Solonin, Yurii [Institute for Problems of Materials Science, NAS of Ukraine, 3, Krzhyzhanovsky Str., 03680 Kyiv-142 (Ukraine); Züttel, Andreas [EMPA Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf (Switzerland); Ecole polytechnique fédérale de Lausanne (EPFL), Institut des sciences et ingénierie chimiques, CH-1015 Lausanne (Switzerland)

    2015-02-05

    Highlights: • Morphology of gas atomised powders depends on the alloy composition. • Co substituted alloy electrodes exhibit slow activation and slow degradation. • The corrosion mechanism depends on the alloy composition and solubility of metals. - Abstract: The mechanism of the capacity degradation of LaNi{sub 5}-based alloy electrodes was investigated with a special focus on the influence of the alloy and surface composition, as well as the unique structure obtained by gas atomisation. The electrochemical properties, especially the cycle life curve (i.e. the capacity as a function of the cycle number of LaNi{sub 4.5}Al{sub 0.5}, LaNi{sub 2.5}Co{sub 2.4}Al{sub 0.1}, (La + Mm)Ni{sub 3.5}Co{sub 0.7}Al{sub 0.35}Mn{sub 0.4}Zr{sub 0.05}, and MmNi{sub 4.3}Al{sub 0.2}Mn{sub 0.5} alloy electrodes), was analysed and modelled. The capacity degradation upon cycling is determined by the chemical state of the alloy elements and the solubility of their oxides. The cycle life curves for the alloy electrodes without Co exhibited a rapid activation (3–4 cycles to reach maximum capacity), as well as rapid degradation (130–180 cycles for 50% maximum discharge capacity). LaNi{sub 2.5}Co{sub 2.4}Al{sub 0.1} and (La + Mm)Ni{sub 3.5}Co{sub 0.7}Al{sub 0.35}Mn{sub 0.4}Zr{sub 0.05} alloy electrodes activated after 7–10 cycles and showed very stable discharge behaviour (more than 400 cycles). The Co-containing alloy electrodes primarily lose the cycle stability because of mechanical decrepitation, whereas the alloys without Co suffer from selective dissolution of the unstable elements in the potential window, which was shown by our model of alloy degradation and confirmed by means of SEM, WDX, and ICP-OES data.

  13. Vacuum thermal-mechanical fatigue behavior of two iron-base alloys

    Science.gov (United States)

    Sheffler, K. D.

    1976-01-01

    The present study extends the concept of in-phase grain boundary ratcheting to two iron-base alloys (Type 304 stainless steel and A286 alloy) and provides a clearer interpretation of out-of-phase grain boundary ratcheting effects observed in the A286 alloy which does not exhibit geometric instability. Elevated-temperature low-cycle thermal-mechanical fatigue tests in an ion-pumped ultrahigh vacuum chamber revealed significant effects of frequency and combined temperature-strain cycling on fatigue life. In-phase thermal cycling (tension at high temperature and compression at low temperature) caused large life reductions in both materials due to grain boundary cavitation caused by unreversed grain boundary sliding (grain boundary ratcheting). Out-of-phase thermal cycling (tension at low temperature and compression at high temperature) also caused large cyclic life reductions in both materials. In the A286 alloy, out-of-phase life reductions are attributed to compressive ratcheting.

  14. Cobalt-based orthopaedic alloys: Relationship between forming route, microstructure and tribological performance

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Bhairav [Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom); Favaro, Gregory [CSM Instruments SA, Rue de la Gare 4, Galileo Center, CH-2034 Peseux (Switzerland); Inam, Fawad [Advanced Composite Training and Development Centre and School of Mechanical and Aeronautical Engineering, Glyndwr University, Mold Road, Wrexham LL11 2AW (United Kingdom); School of Engineering and Materials Science and Nanoforce Technology Ltd, Queen Mary University of London, London E1 4NS (United Kingdom); Reece, Michael J. [School of Engineering and Materials Science and Nanoforce Technology Ltd, Queen Mary University of London, London E1 4NS (United Kingdom); Angadji, Arash [Orthopaedic Research UK, Furlong House, 10a Chandos Street, London W1G 9DQ (United Kingdom); Bonfield, William [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Huang, Jie [Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom); Edirisinghe, Mohan, E-mail: m.edirisinghe@ucl.ac.uk [Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom)

    2012-07-01

    The average longevity of hip replacement devices is approximately 10-15 years, which generally depends on many factors. But for younger generation patients this would mean that revisions may be required at some stage in order to maintain functional activity. Therefore, research is required to increase the longevity to around 25-30 years; a target that was initially set by John Charnley. The main issues related to metal-on-metal (MoM) hip replacement devices are the high wear rates when malpositioned and the release of metallic ions into the blood stream and surrounding tissues. Work is required to reduce the wear rates and limit the amount of metallic ions being leached out of the current MoM materials, to be able to produce an ideal hip replacement material. The most commonly used MoM material is the cobalt-based alloys, more specifically ASTM F75, due to their excellent wear and corrosion resistance. They are either fabricated using the cast or wrought method, however powder processing of these alloys has been shown to improve the properties. One powder processing technique used is spark plasma sintering, which utilises electric current Joule heating to produce high heating rates to sinter powders to form an alloy. Two conventionally manufactured alloys (ASTM F75 and ASTM F1537) and a spark plasma sintered (SPS) alloy were evaluated for their microstructure, hardness, tribological performance and the release of metallic content. The SPS alloy with oxides and not carbides in its microstructure had the higher hardness, which resulted in the lowest wear and friction coefficient, with lower amounts of chromium and molybdenum detected from the wear debris compared to the ASTM F75 and ASTM F1537. In addition the wear debris size and size distribution of the SPS alloy generated were considerably small, indicating a material that exhibits excellent performance and more favourable compared to the current conventional cobalt based alloys used in orthopaedics. - Highlights

  15. [Study on the calcium-based sorbent for removal fluorine during coal combustion].

    Science.gov (United States)

    Li, Shu-ling; Qi, Qing-jie; Liu, Jian-zhong; Cao, Xin-yu; Zhou, Jun-hu; Cen, Ke-fa

    2004-03-01

    In the paper, the reaction of CaO-HF and fluorine removal mechanics at high temperature by blending calcium-based sorbents with coal during coal combustion were discussed, and test results about fluorine retention during coal combustion in fluidized bed and chain-grate furnace were reported. The results identified that lime and calcium-based sorbets developed can restratin the emission of fluorine during coal combustion. The efficiency of fluorine removal can reach 66.7%-70.0% at Ca/F 60-70 by blending lime with coal in fluidized bed combustion, and the efficiency of fluorine removal are between 57.32% and 75.19% by blending calcium-based sorbets with coal in chain-grate furnace combustion. Blending CaO or lime with coal during coal combustion can remove SO2 and HF simultaneously.

  16. MRI compatibility of several early transition metal based alloys and its influencing factors.

    Science.gov (United States)

    Zhou, Da-Bo; Wang, Shao-Gang; Wang, Shao-Ping; Ai, Hong-Jun; Xu, Jian

    2017-02-03

    Magnetic resonance imaging (MRI) compatibility of three early transition metal (ETM) based alloys was assessed in vitro with agarose gel as a phantom, including Zr-20Nb, near-equiatomic (TiZrNbTa)90 Mo10 and Nb-60Ta-2Zr, together with pure tantalum and L605 Co-Cr alloy for comparison. The artifact extent in the MR image was quantitatively characterized according to the maximum area of 2D images and the total volume in reconstructed 3D images with a series of slices under acquisition by fast spin echo (FSE) sequence and gradient echo (GRE) sequence. It was indicated that the artifacts extent of L605 Co-Cr alloy with a higher magnetic susceptibility (χv ) was approximately 3-fold greater than that of the ETM-based alloys with χv in the range of 160-250 ppm. In the ETM group, the MRI compatibility of the materials can be ranked in a sequence of Zr-20Nb, pure tantalum, (TiZrNbTa)90 Mo10 and Nb-60Ta-2Zr. In addition, using a rabbit cadaver with the implanted tube specimens as a model for ex vivo assessment, it was confirmed that the artifact severity of Nb-60Ta-2Zr alloy is significantly reduced in comparison with the L605 alloy. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017. © 2017 Wiley Periodicals, Inc.

  17. New Platinum Alloy Catalysts for Oxygen Electroreduction Based on Alkaline Earth Metals

    DEFF Research Database (Denmark)

    Vej-Hansen, Ulrik Grønbjerg; Escudero-Escribano, M.; Velazquez-Palenzuela, Amado Andres

    2017-01-01

    The energy efficiency of polymer electrolyte membrane fuel cells is mainly limited by overpotentials related to the oxygen reduction reaction (ORR). In this paper, we present new platinum alloys which are active for the ORR and based on alloying Pt with very abundant elements, such as Ca. Theoret......The energy efficiency of polymer electrolyte membrane fuel cells is mainly limited by overpotentials related to the oxygen reduction reaction (ORR). In this paper, we present new platinum alloys which are active for the ORR and based on alloying Pt with very abundant elements, such as Ca....... Theoretical calculations suggested that Pt5Ca and Pt5Sr should be active for the ORR. Electrochemical measurements show that the activity of sputter-cleaned polycrystalline Pt5Ca and Pt5Sr electrodes is enhanced by a factor of 5–7 relative to polycrystalline Pt. Accelerated stability testing shows that after...... 10,000 electrochemical cycles, the alloys still retain over half their activity. The stability is thus not quite on par with the similar Pt-lanthanide alloys, possibly due to the somewhat lower heat of formation....

  18. Pack cementation diffusion coatings for Fe-base and refractory alloys. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, R.A. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering

    1998-03-10

    With the aid of computer-assisted calculations of the equilibrium vapor pressures in halide-activated cementation packs, processing conditions have been identified and experimentally verified for the codeposition of two or more alloying elements in a diffusion coating on a variety of steels and refractory metal alloys. A new comprehensive theory to treat the multi-component thermodynamic equilibria in the gas phase for several coexisting solid phases was developed and used. Many different processes to deposit various types of coatings on several types of steels were developed: Cr-Si codeposition for low- or medium-carbon steels, Cr-Al codeposition on low-carbon steels to yield either a Kanthal-type composition (Fe-25Cr-4Al in wt.%) or else a (Fe, Cr){sub 3}Al surface composition. An Fe{sub 3}Al substrate was aluminized to achieve an FeAl surface composition, and boron was also added to ductilize the coating. The developmental Cr-lean ORNL alloys with exceptional creep resistance were Cr-Al coated to achieve excellent oxidation resistance. Alloy wires of Ni-base were aluminized to provide an average composition of Ni{sub 3}Al for use as welding rods. Several different refractory metal alloys based on Cr-Cr{sub 2}Nb have been silicided, also with germanium additions, to provide excellent oxidation resistance. A couple of developmental Cr-Zr alloys were similarly coated and tested.

  19. Fabrication and study of double sintered TiNi-based porous alloys

    Science.gov (United States)

    Sergey, Anikeev; Valentina, Hodorenko; Timofey, Chekalkin; Victor, Gunther; Ji-hoon, Kang; Ji-soon, Kim

    2017-05-01

    Double-sintered porous TiNi-based alloys were fabricated and their structural characteristics and physico-mechanical properties were investigated. A fabrication technology of powder mixtures is elaborated in this article. Sintering conditions were chosen experimentally to ensure good structure and properties. The porous alloys were synthesized by solid-state double diffusion sintering (DDS) of Ti-Ni powder and prepare to obtain dense, crack-free, and homogeneous samples. The Ti-Ni compound sintered at various temperatures was investigated by scanning electron microscopy. Phase composition of the sintered alloys was determined by x-ray diffraction. Analysis of the data confirmed the morphology and structural parameters. Mechanical and physical properties of the sintered alloys were evaluated. DDS at 1250 °C was found to be optimal to produce porous samples with a porosity of 56% and mean pore size of 90 μm. Pore size distribution was unimodal within the narrow range of values. The alloys present enhanced strength and ductility, owing to both the homogeneity of the macrostructure and relative elasticity of the bulk, which is hardened by the Ni-rich precipitates. These results suggest the possibility to manufacture porous TiNi-based alloys for application as a new class of dental implants.

  20. Adhesion property of epoxidized natural rubber (ENR-based adhesives containing calcium carbonate

    Directory of Open Access Journals (Sweden)

    2008-06-01

    Full Text Available The adhesion property (i.e. viscosity, loop tack and peel strength of epoxidized natural rubber (ENR 25 and ENR 50 grade-based pressure-sensitive adhesive was studied in the presence of calcium carbonate. The range of calcium carbonate loaded was from 10 to 50 parts per hundred parts of rubber (phr. Coumarone-indene resin was used as the tackifier and its concentration was fixed at 80 phr. Toluene was chosen as the solvent throughout the investigation. The substrates (PET film/paper were coated with the adhesive using a SHEEN hand coater at a coating thickness of 60 µm. Viscosity of the adhesive was measured by a HAAKE Rotary Viscometer whereas loop tack and peel strength were determined by a Llyod Adhesion Tester operating at 30 cm/min. Results show that viscosity of ENR-based adhesives increases gradually with increase in calcium carbonate loading due to the concentration effect of the filler. However, for loop tack and peel strength, it passes through a maximum at 30 phr calcium carbonate, an observation which is attributed to the optimum wettability of adhesive on the substrate at this adhesive composition. ENR 25-based adhesive consistently exhibits higher adhesion property than ENR 50 for all calcium carbonate loadings studied.

  1. VANADIUM ALLOYS

    Science.gov (United States)

    Smith, K.F.; Van Thyne, R.J.

    1959-05-12

    This patent deals with vanadium based ternary alloys useful as fuel element jackets. According to the invention the ternary vanadium alloys, prepared in an arc furnace, contain from 2.5 to 15% by weight titanium and from 0.5 to 10% by weight niobium. Characteristics of these alloys are good thermal conductivity, low neutron capture cross section, good corrosion resistance, good welding and fabricating properties, low expansion coefficient, and high strength.

  2. Bioactivity evaluation of commercial calcium phosphate-based bioceramics for bone regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Borrós, S.; Mas, A.

    2016-11-01

    Calcium phosphate-based bioceramics constitute a great promise for bone tissue engineering as they chemically resemble to mammalian bone and teeth. Their use is a viable alternative for bone regeneration as it avoids the use of autografts and allografts, which usually involves immunogenic reactions and patient’s discomfort. This work evolves around the study of the bioactivity potential of different commercially available bone substitutes based in calcium phosphate through the characterization of their ionic exchangeability when immersed in simulated body fluid (SBF). (Author)

  3. Nanoneedle transistor-based sensors for the selective detection of intracellular calcium ions.

    Science.gov (United States)

    Son, Donghee; Park, Sung Young; Kim, Byeongju; Koh, Jun Tae; Kim, Tae Hyun; An, Sangmin; Jang, Doyoung; Kim, Gyu Tae; Jhe, Wonho; Hong, Seunghun

    2011-05-24

    We developed a nanoneedle transistor-based sensor (NTS) for the selective detection of calcium ions inside a living cell. In this work, a single-walled carbon nanotube-based field effect transistor (swCNT-FET) was first fabricated at the end of a glass nanopipette and functionalized with Fluo-4-AM probe dye. The selective binding of calcium ions onto the dye molecules altered the charge state of the dye molecules, resulting in the change of the source-drain current of the swCNT-FET as well as the fluorescence intensity from the dye. We demonstrated the electrical and fluorescence detection of the concentration change of intracellular calcium ions inside a HeLa cell using the NTS.

  4. Durability Study on High Calcium Fly Ash Based Geopolymer Concrete

    Directory of Open Access Journals (Sweden)

    Ganesan Lavanya

    2015-01-01

    Full Text Available This study presents an investigation into the durability of geopolymer concrete prepared using high calcium fly ash along with alkaline activators when exposed to 2% solution of sulfuric acid and 5% magnesium sulphate for up to 45 days. The durability was also assessed by measuring water absorption and sorptivity. Ordinary Portland cement concrete was also prepared as control concrete. The grades chosen for the investigation were M20, M40, and M60. The alkaline solution used for present study is the combination of sodium silicate and sodium hydroxide solution with the ratio of 2.50. The molarity of sodium hydroxide was fixed as 12. The test specimens were 150×150×150 mm cubes, 100×200 mm cylinders, and 100×50 mm discs cured at ambient temperature. Surface deterioration, density, and strength over a period of 14, 28, and 45 days were observed. The results of geopolymer and ordinary Portland cement concrete were compared and discussed. After 45 days of exposure to the magnesium sulfate solution, the reduction in strength was up to 12% for geopolymer concrete and up to 25% for ordinary Portland cement concrete. After the same period of exposure to the sulphuric acid solution, the compressive strength decrease was up to 20% for geopolymer concrete and up to 28% for ordinary Portland cement concrete.

  5. Computational studies of physical properties of Nb-Si based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ouyang, Lizhi [Middle Tennessee State Univ., Murfreesboro, TN (United States)

    2015-04-16

    The overall goal is to provide physical properties data supplementing experiments for thermodynamic modeling and other simulations such as phase filed simulation for microstructure and continuum simulations for mechanical properties. These predictive computational modeling and simulations may yield insights that can be used to guide materials design, processing, and manufacture. Ultimately, they may lead to usable Nb-Si based alloy which could play an important role in current plight towards greener energy. The main objectives of the proposed projects are: (1) developing a first principles method based supercell approach for calculating thermodynamic and mechanic properties of ordered crystals and disordered lattices including solid solution; (2) application of the supercell approach to Nb-Si base alloy to compute physical properties data that can be used for thermodynamic modeling and other simulations to guide the optimal design of Nb-Si based alloy.

  6. Atomic scale properties of magnetic Mn-based alloys probed by emission Mössbauer spectroscopy

    CERN Multimedia

    Mn-based alloys are characterized by a wealth of properties, which are of interest both from fundamental physics point of view and particularly attractive for different applications in modern technology: from magnetic storage to sensing and spin-based electronics. The possibility to tune their magnetic properties through post-growth thermal processes and/or stoichiometry engineering is highly important in order to target different applications (i.e. Mn$_{x}$Ga) or to increase their Curie temperature above room temperature (i.e. off-stoichiometric MnSi). In this project, the Mössbauer effect will be applied at $^{57}$Fe sites following implantation of radioactive $^{57}$Mn, to probe the micro-structure and magnetism of Mn-based alloys on the atomic-scale. The proposed experimental plan is devoted to establish a direct correlation between the local structure and bulk magnetism (and other physical properties) of Mn-based alloys.

  7. Thermodynamic Tuning of Mg-Based Hydrogen Storage Alloys: A Review

    Science.gov (United States)

    Zhu, Min; Lu, Yanshan; Ouyang, Liuzhang; Wang, Hui

    2013-01-01

    Mg-based hydrides are one of the most promising hydrogen storage materials because of their relatively high storage capacity, abundance, and low cost. However, slow kinetics and stable thermodynamics hinder their practical application. In contrast to the substantial progress in the enhancement of the hydrogenation/dehydrogenation kinetics, thermodynamic tuning is still a great challenge for Mg-based alloys. At present, the main strategies to alter the thermodynamics of Mg/MgH2 are alloying, nanostructuring, and changing the reaction pathway. Using these approaches, thermodynamic tuning has been achieved to some extent, but it is still far from that required for practical application. In this article, we summarize the advantages and disadvantages of these strategies. Based on the current progress, finding reversible systems with high hydrogen capacity and effectively tailored reaction enthalpy offers a promising route for tuning the thermodynamics of Mg-based hydrogen storage alloys. PMID:28788353

  8. Room temperature synthesis of Ni-based alloy nanoparticles by radiolysis.

    Energy Technology Data Exchange (ETDEWEB)

    Nenoff, Tina Maria; Berry, Donald T.; Lu, Ping; Leung, Kevin; Provencio, Paula Polyak; Stumpf, Roland Rudolph; Huang, Jian Yu; Zhang, Zhenyuan

    2009-09-01

    Room temperature radiolysis, density functional theory, and various nanoscale characterization methods were used to synthesize and fully describe Ni-based alloy nanoparticles (NPs) that were synthesized at room temperature. These complementary methods provide a strong basis in understanding and describing metastable phase regimes of alloy NPs whose reaction formation is determined by kinetic rather than thermodynamic reaction processes. Four series of NPs, (Ag-Ni, Pd-Ni, Co-Ni, and W-Ni) were analyzed and characterized by a variety of methods, including UV-vis, TEM/HRTEM, HAADF-STEM and EFTEM mapping. In the first focus of research, AgNi and PdNi were studied. Different ratios of Ag{sub x}- Ni{sub 1-x} alloy NPs and Pd{sub 0.5}- Ni{sub 0.5} alloy NP were prepared using a high dose rate from gamma irradiation. Images from high-angle annular dark-field (HAADF) show that the Ag-Ni NPs are not core-shell structure but are homogeneous alloys in composition. Energy filtered transmission electron microscopy (EFTEM) maps show the homogeneity of the metals in each alloy NP. Of particular interest are the normally immiscible Ag-Ni NPs. All evidence confirmed that homogeneous Ag-Ni and Pd-Ni alloy NPs presented here were successfully synthesized by high dose rate radiolytic methodology. A mechanism is provided to explain the homogeneous formation of the alloy NPs. Furthermore, studies of Pd-Ni NPs by in situ TEM (with heated stage) shows the ability to sinter these NPs at temperatures below 800 C. In the second set of work, CoNi and WNi superalloy NPs were attempted at 50/50 concentration ratios using high dose rates from gamma irradiation. Preliminary results on synthesis and characterization have been completed and are presented. As with the earlier alloy NPs, no evidence of core-shell NP formation occurs. Microscopy results seem to indicate alloying occurred with the CoNi alloys. However, there appears to be incomplete reduction of the Na{sub 2}WO{sub 4} to form the W

  9. Efficacy of three methods for inserting calcium hydroxide-based paste in root canals.

    Science.gov (United States)

    Galvão, Thales; Camargo, Bernardo; Armada, Luciana; Alves, Flávio

    2017-06-01

    To compare the quality of calcium hydroxide paste fillings performed by three different techniques. Sixty extracted maxillary central incisors, with previous root canal treatment, were decoronated and the gutta-percha was completely removed from the root canals. Subsequently, the canals were filled with a calcium hydroxide-based paste composed of calcium hydroxide, bismuth carbonate, and glycerin. The study samples were divided into the following three groups on the basis of three insertion techniques (n = 20, each): conventional technique using a hand instrument (MAN), rotary Lentulo spiral (LEN) technique, and a combined technique combining conventional hand files with sonic activation through the EndoActivator device (EA). The quality of fillings was evaluated radiographically by two examiners on the basis of the amount of voids and the apical limit. The canals filled with LEN or MAN had less void volume compared to the EA technique ( P >0.01), with no significant differences between them. Considering the apical limits, the three tested techniques showed comparable results ( P >0.05). A combined approach utilizing hand files with sonic activation showed no enhancements over the LEN or MAN techniques on the quality of intracanal placement of calcium hydroxide paste. Key words: Calcium hydroxide placement, EndoActivator, Lentulo spirals, intracanal medication, root canal treatment.

  10. Shear bond strength of a ceromer to noble and base metal alloys

    Directory of Open Access Journals (Sweden)

    Dorriz H.

    2006-08-01

    Full Text Available Background and Aim: The improvement of the physical and chemical properties of resins as well as great advances achieved in the field of chemical bonding of resin to metal has changed the trend of restorative treatments. Today the second generation of laboratory resins have an important role in the restoration of teeth. The clinical bond strength should be reliable in order to gain successful results. In this study the shear bond strength (SBS between targis (a ceromer and two alloys (noble and base metal was studied and the effect of thermocycling on the bond investigated. Materials and Methods: In this experimental study, alloys samples were prepared according to the manufacturer. After sandblasting of bonding surfaces with 50µ AI2o3 Targis was bonded to the alloy using Targis I link. All of the samples were placed in 37°C water for a period of 24 hours. Then half of the samples were subjected to 1000 cycles of thermocycling at temperatures of 5°C and 55°C. Planear shear test was used to test the bond strength in the Instron machine with the speed rate of 0.5mm/min. Data were analyzed by SPSS software. Two-way analysis of variance was used to compare the bond strength among the groups. T test was used to compare the alloys. The influence of thermocycling and alloy type on bond strength was studied using Mann Whitney test. P<0.05 was considered as the limit of significance. Result: The studied alloys did not differ significantly, when the samples were not thermocycled (P=0.136 but after thermocycling a significant difference was observed in SBS of resin to different alloys (P=000.1. Thermal stress and alloy type had significant interaction, with regard to shear bond strength (P=0.003. There was a significant difference in SBS before and after thermocycling in noble alloys (P=0.009, but this was not true in base metals (P=0.29. Maximum SBS (19.09 Mpa belonged to Degubond 4, before thermocycling. Minimum SBS (8.21 Mpa was seen in Degubond 4

  11. Experimental Investigation on Laser Impact Welding of Fe-Based Amorphous Alloys to Crystalline Copper

    Science.gov (United States)

    Wang, Xiao; Luo, Yapeng; Huang, Tao; Liu, Huixia

    2017-01-01

    Recently, amorphous alloys have attracted many researchers’ attention for amorphous structures and excellent properties. However, the welding of amorphous alloys to traditional metals in the microscale is not easy to realize in the process with amorphous structures unchanged, which restrains the application in industry. In this paper, a new method of welding Fe-based amorphous alloys (GB1K101) to crystalline copper by laser impact welding (LIW) is investigated. A series of experiments was conducted under different laser energies, during which Fe-based amorphous alloys and crystalline copper were welded successfully by LIW. In addition, the microstructure and mechanical properties of welding joints were observed and measured, respectively. The results showed that the surface wave and springback were observed on the flyer plate after LIW. The welding interface was straight or wavy due to different plastic deformation under different laser energies. The welding interface was directly bonded tightly without visible defects. No visible element diffusion and intermetallic phases were found in the welding interface. The Fe-based amorphous alloys retained amorphous structures after LIW under the laser energy of 835 mJ. The nanoindentation hardness across the welding interface showed an increase on both sides of the welding interface. The results of the lap shearing test showed that the fracture position was on the side of copper coil. PMID:28772886

  12. Experimental Investigation on Laser Impact Welding of Fe-Based Amorphous Alloys to Crystalline Copper.

    Science.gov (United States)

    Wang, Xiao; Luo, Yapeng; Huang, Tao; Liu, Huixia

    2017-05-12

    Recently, amorphous alloys have attracted many researchers' attention for amorphous structures and excellent properties. However, the welding of amorphous alloys to traditional metals in the microscale is not easy to realize in the process with amorphous structures unchanged, which restrains the application in industry. In this paper, a new method of welding Fe-based amorphous alloys (GB1K101) to crystalline copper by laser impact welding (LIW) is investigated. A series of experiments was conducted under different laser energies, during which Fe-based amorphous alloys and crystalline copper were welded successfully by LIW. In addition, the microstructure and mechanical properties of welding joints were observed and measured, respectively. The results showed that the surface wave and springback were observed on the flyer plate after LIW. The welding interface was straight or wavy due to different plastic deformation under different laser energies. The welding interface was directly bonded tightly without visible defects. No visible element diffusion and intermetallic phases were found in the welding interface. The Fe-based amorphous alloys retained amorphous structures after LIW under the laser energy of 835 mJ. The nanoindentation hardness across the welding interface showed an increase on both sides of the welding interface. The results of the lap shearing test showed that the fracture position was on the side of copper coil.

  13. The strengthening mechanism of a nickel-based alloy after laser shock processing at high temperatures

    Directory of Open Access Journals (Sweden)

    Yinghong Li, Liucheng Zhou, Weifeng He, Guangyu He, Xuede Wang, Xiangfan Nie, Bo Wang, Sihai Luo and Yuqin Li

    2013-01-01

    Full Text Available We investigated the strengthening mechanism of laser shock processing (LSP at high temperatures in the K417 nickel-based alloy. Using a laser-induced shock wave, residual compressive stresses and nanocrystals with a length of 30–200 nm and a thickness of 1 μm are produced on the surface of the nickel-based alloy K417. When the K417 alloy is subjected to heat treatment at 900 °C after LSP, most of the residual compressive stress relaxes while the microhardness retains good thermal stability; the nanocrystalline surface has not obviously grown after the 900 °C per 10 h heat treatment, which shows a comparatively good thermal stability. There are several reasons for the good thermal stability of the nanocrystalline surface, such as the low value of cold hardening of LSP, extreme high-density defects and the grain boundary pinning of an impure element. The results of the vibration fatigue experiments show that the fatigue strength of K417 alloy is enhanced and improved from 110 to 285 MPa after LSP. After the 900 °C per 10 h heat treatment, the fatigue strength is 225 MPa; the heat treatment has not significantly reduced the reinforcement effect. The feature of the LSP strengthening mechanism of nickel-based alloy at a high temperature is the co-working effect of the nanocrystalline surface and the residual compressive stress after thermal relaxation.

  14. Resistivity and Passivity Characterization of Ni-Base Glassy Alloys in NaOH Media

    Directory of Open Access Journals (Sweden)

    Khadijah M. Emran

    2018-01-01

    Full Text Available Resistivity and passivation behavior of two Ni-base bulk metallic glasses, with the nominal composition of Ni70Cr21Si0.5B0.5P8C ≤ 0.1Co ≤ 1Fe ≤ 1 (VZ1 and Ni72.65Cr7.3-Si6.7B2.15C ≤ 0.06Fe8.2Mo3 (VZ2, in various concentrations of NaOH solutions were studied. The investigations involved cyclic polarization (CP, electrochemical impedance spectroscopy (EIS, and electrochemical frequency modulation (EFM methods. Cyclic polarization measurements showed spontaneous passivation for both Ni-base glassy alloys at all alkaline concentrations, due to the presence of chromium as an alloying element that formed an oxide film on the alloy surface. The EIS analysis showed that the passive layers grown on the two Ni-base glassy alloy surfaces are formed by a double oxide layer structure. Scanning electron microscope (SEM examinations of the electrode surface showed Cr, Ni, Fe, and O rich corrosion products that reduced the extent of corrosion damage. Atomic force microscopy (AFM imaging technique was used to evaluate the topographic and morphologic features of surface layers formed on the surface of the alloys.

  15. Dendrite-Free Potassium–Oxygen Battery Based on a Liquid Alloy Anode

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Wei [Advanced Materials; School; Lau, Kah Chun [Department of Physics; Lei, Yu [Advanced Materials; Liu, Ruliang [Materials Science Institute, PCFM Lab and GDHPPC Lab, School of Chemistry, Sun Yat-sen University, Guangzhou 510275, China; Qin, Lei [Advanced Materials; School; Yang, Wei [Advanced Materials; Li, Baohua [Advanced Materials; Curtiss, Larry A. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States; Zhai, Dengyun [Advanced Materials; Kang, Feiyu [Advanced Materials; School

    2017-03-20

    The safety issue caused by the dendrite growth is not only a key research problem in lithium-ion batteries but also a critical concern in alkali metal (i.e., Li, Na, and K) oxygen batteries where a solid metal is usually used as the anode. Herein, we demonstrate the first dendrite-free K-O-2 battery at ambient temperature based on a liquid Na K alloy anode. The unique liquid liquid connection between the liquid alloy and the electrolyte in our alloy anode-based battery provides a homogeneous and robust anode electrolyte interface. Meanwhile, we manage to show that the Na K alloy is only compatible in K-O-2 batteries but not in Na-O-2 batteries, which is mainly attributed to the stronger reducibility of potassium and relatively more favorable thermodynamic formation of KO, over NaO2 during the discharge process. It is observed that our K-O-2 battery based on a liquid alloy anode shows a long cycle life (over 620 h) and a low discharge charge overpotential (about 0.05 V at initial cycles). Moreover, the mechanism investigation into the K-O-2 cell degradation shows that the 02 crossover effect and the ether electrolyte instability are the critical problems for K-O-2 batteries. In a word, this study provides a new route to solve the problems caused by the dendrite growth in alkali metal oxygen batteries.

  16. Using the PSCPCSP computer software for optimization of the composition of industrial alloys and development of new high-temperature nickel-base alloys

    Science.gov (United States)

    Rtishchev, V. V.

    1995-11-01

    Using computer programs some foreign firms have developed new deformable and castable high-temperature nickel-base alloys such as IN, Rene, Mar-M, Udimet, TRW, TM, TMS, TUT, with equiaxial, columnar, and single-crystal structures for manufacturing functional and nozzle blades and other parts of the hot duct of transport and stationary gas-turbine installations (GTI). Similar investigations have been carried out in Russia. This paper presents examples of the use of the PSCPCSP computer software for a quantitative analysis of structural und phase characteristics and properties of industrial alloys with change (within the grade range) in the concentrations of the alloying elements for optimizing the composition of the alloys and regimes of their heat treatment.

  17. Fluorine-fixing efficiency on calcium-based briquette: pilot experiment, demonstration and promotion.

    Science.gov (United States)

    Yang, Jiao-lan; Chen, Dong-qing; Li, Shu-min; Yue, Yin-ling; Jin, Xin; Zhao, Bing-cheng; Ying, Bo

    2010-02-05

    The fluorosis derived from coal burning is a very serious problem in China. By using fluorine-fixing technology during coal burning we are able to reduce the release of fluorides in coal at the source in order to reduce pollution to the surrounding environment by coal burning pollutants as well as decrease the intake and accumulating amounts of fluorine in the human body. The aim of this study was to conduct a pilot experiment on calcium-based fluorine-fixing material efficiency during coal burning to demonstrate and promote the technology based on laboratory research. A proper amount of calcium-based fluorine sorbent was added into high-fluorine coal to form briquettes so that the fluorine in high-fluorine coal can be fixed in coal slag and its release into atmosphere reduced. We determined figures on various components in briquettes and fluorine in coal slag as well as the concentrations of indoor air pollutants, including fluoride, sulfur dioxide and respirable particulate matter (RPM), and evaluated the fluorine-fixing efficiency of calcium-based fluorine sorbents and the levels of indoor air pollutants. Pilot experiments on fluorine-fixing efficiency during coal burning as well as its demonstration and promotion were carried out separately in Guiding and Longli Counties of Guizhou Province, two areas with coal burning fluorosis problems. If the calcium-based fluorine sorbent mixed coal was made into honeycomb briquettes the average fluorine-fixing ratio in the pilot experiment was 71.8%. If the burning calcium-based fluorine-fixing bitumite was made into a coalball, the average of fluorine-fixing ratio was 77.3%. The concentration of fluoride, sulfur dioxide and PM10 of indoor air were decreased significantly. There was a 10% increase in the cost of briquettes due to the addition of calcium-based fluorine sorbent. The preparation process of calcium-based fluorine-fixing briquette is simple yet highly flammable and it is applicable to regions with abundant

  18. Chitosan based hydrogel assisted spongelike calcium phosphate mineralization for in-vitro BSA release.

    Science.gov (United States)

    Salama, Ahmed

    2017-12-07

    New chitosan-g- poly (3-sulfopropyl methacrylate), CHI-g-P(SPMA), hydrogel was prepared by free radical polymerization process and investigated as a template for biomimetic spongelike calcium phosphate mineralization in a solution mimicking physiological condition. Infrared spectroscopy, scanning electron microscopy, X-ray diffraction and transmission electron microscopy confirmed the predominant formation of rod-like hydroxyapatite. The swelling behavior of the nanocomposite was evaluated at different pHs and different saline concentrations. Bovine serum albumin (BSA), as a model protein drug, was loaded in the CHI-g-P(SPMA)/calcium phosphate hybrid. The BSA release behavior was investigated and the results suggested CHI-g-P(SPMA)/calcium phosphate hybrid as controlled release carrier. These results suggest that next generation of polysaccharides based hybrid materials could be interesting for biomedical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Calcium Oxide Supported on Monoclinic Zirconia as a Highly Active Solid Base Catalyst

    NARCIS (Netherlands)

    Frey, A.M.; Haasterecht, van T.; Jong, de K.P.; Bitter, J.H.

    2013-01-01

    Calcium oxide supported on ZrO2 is a highly active catalyst for base-catalyzed reactions such as aldol-type reactions and transesterification reactions. The role of key parameters during preparation, that is, impregnation versus precipitation, heat treatment, and metal oxide loading on the basicity

  20. Submillisievert coronary calcium quantification using model-based iterative reconstruction : A within-patient analysis

    NARCIS (Netherlands)

    den Harder, Annemarie M; Wolterink, Jelmer M; Willemink, Martin J; Schilham, Arnold M R; de Jong, Pim A; Budde, Ricardo P J; Nathoe, Hendrik M; Išgum, Ivana; Leiner, Tim

    2016-01-01

    PURPOSE: To determine the effect of model-based iterative reconstruction (IR) on coronary calcium quantification using different submillisievert CT acquisition protocols. METHODS: Twenty-eight patients received a clinically indicated non contrast-enhanced cardiac CT. After the routine dose

  1. Pulp capping with adhesive resin-based composite vs. calcium hydroxide: a review.

    Science.gov (United States)

    Schuurs, A H; Gruythuysen, R J; Wesselink, P R

    2000-12-01

    The results of some short-term experiments suggest that direct capping of a vital pulp with the modern resin-based composite systems may be as effective as capping with calcium hydroxide. Total cavity etching with 10% phosphoric acid seems to be safe for the exposed pulp, but unless annulled by calcium hydroxide 35% phosphoric acid may be disastrous. For hemostasis and cleaning of the pulp wound both sodium hypochlorite and saline seem suitable, whereas the effectiveness of a 2% chlorhexidine solution is questionable. Although hard-setting calcium hydroxide cements may induce the formation of dentin bridges, they appear not to provide an effective long-term seal against bacterial factors. Within a few years, the majority of mechanically exposed and capped pulps show infection and necrosis due to microleakage of such capping materials and tunnel defects in the dentin bridges. It is unknown whether newer types of resin containing calcium-hydroxide-products will act as a permanent barrier. The cytotoxicity of the resin-based composites and the temperature rise during polymerisation may not be of concern, but microleakage, sensitisation and allergic reactions may pose problems. Based on available data, pulp capping with resin-based composites may be said to be promising, but more and long-term research is mandatory before the method can be recommended.

  2. The environmentally-assisted cracking behaviour in the transition region of nickel-base alloy/low-alloy steel dissimilar weld joints under simulated BWR conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ritter, S.; Seifert, H.P.; Leber, H.J. [Paul Scherrer Institute, Nuclear Energy and Safety Research Department, Lab for Nuclear Materials, 5232 Villigen PSI (Switzerland)

    2011-07-01

    The stress corrosion cracking (SCC) behaviour perpendicular to the fusion line in the transition region between the Alloy 182 nickel-base weld metal and the adjacent low-alloy reactor pressure vessel (RPV) steel of simulated dissimilar metal weld joints was investigated under boiling water reactor normal water chemistry conditions at different stress intensities and chloride concentrations. A special emphasis was placed to the question whether a fast growing inter-dendritic SCC crack in the highly susceptible Alloy 182 weld metal can easily cross the fusion line and significantly propagate into the adjacent low-alloy RPV steel. Cessation of inter-dendritic stress corrosion crack growth was observed in high-purity or sulphate-containing oxygenated water under periodical partial unloading or constant loading conditions with stress intensity factors below 60 MPa-m{sup 1/2} for those parts of the crack front, which reached the fusion line. In chloride containing water, on the other hand, the inter-dendritic stress corrosion crack in the Alloy 182 weld metal very easily crossed the fusion line and further propagated with a very high growth rate as a transgranular crack into the heat-affected zone and base material of the adjacent low-alloy steel. (authors)

  3. Comparative investigations of structure and properties of micro-arc wollastonite-calcium phosphate coatings on titanium and zirconium-niobium alloy

    Directory of Open Access Journals (Sweden)

    M.B. Sedelnikova

    2017-09-01

    Full Text Available Investigation results of micro-arc wollastonite–calcium phosphate (W–CaP biocoatings on the pure titanium (Ti and Zr–1wt.%Nb (Zr–1Nb alloy were presented. The voltages of 150–300 V generate the micro-arc oxidation (MAO process with the initial amplitude current of 150–550 A and 100–350 A for Ti and Zr–1Nb substrates, respectively. The identical dependencies of changes of the coating thickness, surface roughness and adhesion strength on the process voltage were revealed for the both substrates. The W–CaP coatings with the thickness of 10–11 μm were formed on Ti and Zr–1Nb under the low process voltage of 130–150 V. Elongated wollastonite particles with the size in the range of 40–100 μm were observed in such coatings. The structure of the coatings on Ti was presented by the X–ray amorphous and crystalline phases. The X–ray reflexes relating to the crystalline phases of Ti and wollastonite were observed only in XRD patterns of the coatings deposited under 130–200 V on Ti. While, the crystalline structure with phases of CaZr4(PO46, β–ZrP2O7, ZrO2, and Zr was detected in the coatings on Zr–1Nb. FT–IRS, XRD, SEM, and TEM data confirmed that the increase of the process voltage to 300 V leads to the dissociation of the wollastonite. No toxic effect of specimens on a viability, morphology and motility of human adipose–derived multipotent mesenchymal stem cells was revealed in vitro.

  4. A Comparison in Mechanical Properties of Cermets of Calcium Silicate with Ti-55Ni and Ti-6Al-4V Alloys for Hard Tissues Replacement

    Directory of Open Access Journals (Sweden)

    Azim Ataollahi Oshkour

    2014-01-01

    Full Text Available This study investigated the impact of calcium silicate (CS content on composition, compressive mechanical properties, and hardness of CS cermets with Ti-55Ni and Ti-6Al-4V alloys sintered at 1200°C. The powder metallurgy route was exploited to prepare the cermets. New phases of materials of Ni16Ti6Si7, CaTiO3, and Ni31Si12 appeared in cermet of Ti-55Ni with CS and in cermet of Ti-6Al-4V with CS, the new phases Ti5Si3, Ti2O, and CaTiO3, which were emerged during sintering at different CS content (wt%. The minimum shrinkage and density were observed in both groups of cermets for the 50 and 100 wt% CS content, respectively. The cermets with 40 wt% of CS had minimum compressive Young’s modulus. The minimum of compressive strength and strain percentage at maximum load were revealed in cermets with 50 and 40 wt% of CS with Ti-55Ni and Ti-6Al-4V cermets, respectively. The cermets with 80 and 90 wt% of CS showed more plasticity than the pure CS. It concluded that the composition and mechanical properties of sintered cermets of Ti-55Ni and Ti-6Al-4V with CS significantly depend on the CS content in raw cermet materials. Thus, the different mechanical properties of the cermets can be used as potential materials for different hard tissues replacements.

  5. Microstructural Analysis of Ti-Based Shape Memory Alloys Following the Electrochemical Corrosion in Artificial Saliva

    Science.gov (United States)

    Baciu, C.; Baciu, E. R.; Cimpoeșu, R.; Levente, C. G.; Bosinceanu, D. G.; Baciu, M.; Bejinariu, C.

    2017-06-01

    The investigations carried out aimed to highlight the structural modifications occurred in the Ti-based shape memory alloys subject to electrocorrosion in Afnor artificial saliva. The behavior to corrosion was highlighted by fast electrochemical tests, mainly by dynamic potentiometry. From the microstructural analysis we noticed that the specimens of the two Ti-based shape memory alloys show traces of “pitting” corrosion on their surface of diverse sizes, a fact that will raise issues in terms of cytotoxicity due to the corrosion products released.

  6. The fluidity and molding ability of glass-forming Zr-based alloy melt

    Science.gov (United States)

    Ma, Mingzhen; Zong, Haitao; Wang, Haiyan; Qi, Yanpeng; Liang, Sunxing; Song, Aijun; Zhang, Weiguo; Wang, Qiang; Zhang, Xinyu; Jing, Qin; Li, Gong; Liu, Riping

    2008-04-01

    The fluidity and filling ability of glass-forming Zr-based alloy melt in copper mould were investigated both theoretically and experimentally. The major factors which affected the flowing behavior of the metallic melt in the mold were determined, which provides the foundation for overcoming the contradiction between the filling and formation of amorphous alloy during the rapid cooling process of the metallic melts. The casting factors to prepare a metallic ring were discussed and selected. As a result, a Zr-based bulk metallic glass ring was prepared successfully.

  7. A new approach to the hazard classification of alloys based on transformation/dissolution.

    Science.gov (United States)

    Skeaff, James M; Hardy, David J; King, Pierrette

    2008-01-01

    . For the other alloys, we developed a new critical surface area-toxic units (CSA-TU) approach to derive their GHS classification proposals. The CSA-TU approach can be readily applied to other multicomponent alloy systems, without the need to arbitrarily select a particular component among several as the determinant of toxicity. This paper shows how regulatory obligations, such as those mandated by REACH, can be met with a laboratory-based CSA-TU method for deriving hazard classification proposals for alloys, linking to attendant environmental protection management decisions. Drawing on T/D data derived from laboratory testing of the alloy itself, the CSA-TU approach can be applied to establish scientifically defensible decisions on hazard classification proposals for an alloy of interest. The resulting decisions can then be incorporated into environmental management measures in such jurisdictions as the European Union. Based on an approach developed specifically for alloys, the hazard classification decisions can be regarded as relevant, credible, and protective of the environment. Since alloys are usually more resistant to chemical attack than their components, this approach is a considerable improvement over the possibility provided for in the GHS of calculating a hazard classification level for an alloy from the classification levels of its components.

  8. Identification of phase structure of plated zinc alloys based on a linear voltammetry in alkaline solutions

    Directory of Open Access Journals (Sweden)

    Lina V. Petrenko

    2016-12-01

    Full Text Available The purpose of research was the development of new and effective technique of electroplatings phase composition analysis by inversion voltammetric methods. As a result the possibility of the phase composition of the plated zinc-based alloys identification using anodic linear voltammetry in alkaline solutions was shown. The phase composition Zn–(0.27–9.4% Fe alloy electroplated from alkaline zincate solutions was defined based on voltammetry data. As part of the Zn–Fe alloys the phase of hexagonal structure was found which is absent in the equilibrium phase diagram. The ratio of hexagonal crystal lattice axes (c/a and the electron concentration (e/a for this phase are significantly different from the corresponding values for the primary solid solution η. From the analysis of c/a and e/a values of investigated Zn–Fe alloy the defined phase was identified as a solid solution phase type ε. It also was shown that anodic linear voltammetry accomplished in alkaline solutions is more sensitive to the identification of the phase composition of zinc alloys than the traditional X-ray method and stripping voltammetry.

  9. Neutronics Evaluation of Lithium-Based Ternary Alloys in IFE Blankets

    Energy Technology Data Exchange (ETDEWEB)

    Jolodosky, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Fratoni, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-11-20

    Pre-conceptual fusion blanket designs require research and development to reflect important proposed changes in the design of essential systems, and the new challenges they impose on related fuel cycle systems. One attractive feature of using liquid lithium as the breeder and coolant is that it has very high tritium solubility and results in very low levels of tritium permeation throughout the facility infrastructure. However, lithium metal vigorously reacts with air and water and presents plant safety concerns. If the chemical reactivity of lithium could be overcome, the result would have a profound impact on fusion energy and associated safety basis. The overriding goal of this project is to develop a lithium-based alloy that maintains beneficial properties of lithium (e.g. high tritium breeding and solubility) while reducing overall flammability concerns. To minimize the number of alloy combinations that must be explored, only those alloys that meet certain nuclear performance metrics will be considered for subsequent thermodynamic study. The specific scope of this study is to evaluate the neutronics performance of lithium-based alloys in the blanket of an inertial confinement fusion (ICF) engine. The results of this study will inform the development of lithium alloys that would guarantee acceptable neutronics performance while mitigating the chemical reactivity issues of pure lithium.

  10. Progress in research on cold crucible directional solidification of titanium based alloys

    Directory of Open Access Journals (Sweden)

    Chen Ruirun

    2014-07-01

    Full Text Available Cold crucible directional solidification (CCDS is a newly developed technique, which combines the advantages of the cold crucible and continuous melting. It can be applied to directionally solidify reactive, high purity and refractory materials. This paper describes the principle of CCDS and its characteristics; development of the measurement and numerical calculation of the magnetic field, flow field and temperature field in CCDS; and the CCDS of Ti based alloys. The paper also reviews original data obtained by some scholars, including the present authors, reported in separate publications in recent years. In Ti based alloys, Ti6Al4V, TiAl alloys and high Nb-containing TiAl alloys, have been directionally solidified in different cold crucibles. The crosssections of the cold crucibles include round, near rectangular and square with different sizes. Tensile testing results show that the elongation of directionally solidified Ti6Al4V can be improved to 12.7% from as cast 5.4%. The strength and the elongation of the directionally solidified Ti47Al2Cr2Nb and Ti44Al6Nb1.0Cr2.0V are 650 MPa/3% and 602.5 MPa/1.20%, respectively. The ingots after CCDS can be used to prepare turbine or engine blades, and are candidates to replace Ni super-alloy at temperatures of 700 to 900 °C.

  11. Tensile properties of a nickel-base alloy subjected to surface severe plastic deformation

    Energy Technology Data Exchange (ETDEWEB)

    Tian, J.W. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN (United States); Dai, K. [Quality Engineering and Software Technology, East Hartford, CT 06108 (United States); Villegas, J.C. [Intel Corporation, Chandler, AZ (United States); Shaw, L. [Department of Chemical, Materials and Biomolecular Engineering, University of Connecticut, Storrs, CT (United States)], E-mail: leon.shaw@uconn.edu; Liaw, P.K. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN (United States); Klarstrom, D.L. [Haynes International, Inc., Kokomo, IN (United States); Ortiz, A.L. [Departamento de Ingenieria Mecanica, Energetica y de los Materiales, Universidad de Extremadura, 06071 Badajoz (Spain)

    2008-10-15

    A surface severe plastic deformation (S{sup 2}PD) method has been applied to bulk specimens of HASTELLOY C-2000 alloy, a nickel-base alloy. The mechanical properties of the processed C-2000 alloy were determined via tensile tests and Vickers hardness measurements, whereas the microstructure was characterized using scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry. The improved tensile strength was related to the nanostructure at the surface region, the residual compressive stresses, and the work-hardened surface layer, all of which resulted from the S{sup 2}PD process. To understand the contributions of these three factors, finite element modeling was performed. It was found that the improved tensile strength could be interpreted based on the contributions of nano-grains, residual stresses, and work hardening.

  12. Gamma prime precipitation mechanisms and solute partitioning in Ni-base alloys

    Science.gov (United States)

    Rojhirunsakool, Tanaporn

    Nickel-base superalloys have been emerged as materials for gas turbines used for jet propulsion and electricity generation. The strength of the superalloys depends mainly from an ordered precipitates of L12 structure, so called gamma prime (gamma') dispersed within the disorder gamma matrix. The Ni-base alloys investigated in this dissertation comprise both model alloy systems based on Ni-Al-Cr and Ni-Al-Co as well as the commercial alloy Rene N5. Classical nucleation and growth mechanism dominates the gamma' precipitation process in slowed-cooled Ni-Al-Cr alloys. The effect of Al and Cr additions on gamma' precipitate size distribution as well as morphological and compositional development of gamma' precipitates were characterized by coupling transmission electron microscopy (TEM) and 3D atom probe (3DAP) techniques. Rapid quenching Ni-Al-Cr alloy experiences a non-classical precipitation mechanism. Structural evolution of the gamma' precipitates formed and subsequent isothermal annealing at 600 °C were investigated by coupling TEM and synchrotron-based high-energy xray diffraction (XRD). Compositional evolution of the non-classically formed gamma' precipitates was determined by 3DAP and Langer, Bar-on and Miller (LBM) method. Besides homogeneous nucleation, the mechanism of heterogeneous gamma' precipitation involving a discontinuous precipitation mechanism, as a function of temperature, was the primary focus of study in case of the Ni-Al-Co alloy. This investigation coupled SEM, SEM-EBSD, TEM and 3DAP techniques. Lastly, solute partitioning and enrichment of minor refractory elements across/at the gamma/ gamma' interfaces in the commercially used single crystal Rene N5 superalloy was investigated by using an advantage of nano-scale composition investigation of 3DAP technique.

  13. Phonon structures of GaN-based random semiconductor alloys

    Science.gov (United States)

    Zhou, Mei; Chen, Xiaobin; Li, Gang; Zheng, Fawei; Zhang, Ping

    2017-12-01

    Accurate modeling of thermal properties is strikingly important for developing next-generation electronics with high performance. Many thermal properties are closely related to phonon dispersions, such as sound velocity. However, random substituted semiconductor alloys AxB1-x usually lack translational symmetry, and simulation with periodic boundary conditions often requires large supercells, which makes phonon dispersion highly folded and hardly comparable with experimental results. Here, we adopt a large supercell with randomly distributed A and B atoms to investigate substitution effect on the phonon dispersions of semiconductor alloys systematically by using phonon unfolding method [F. Zheng, P. Zhang, Comput. Mater. Sci. 125, 218 (2016)]. The results reveal the extent to which phonon band characteristics in (In,Ga)N and Ga(N,P) are preserved or lost at different compositions and q points. Generally, most characteristics of phonon dispersions can be preserved with indium substitution of gallium in GaN, while substitution of nitrogen with phosphorus strongly perturbs the phonon dispersion of GaN, showing a rapid disintegration of the Bloch characteristics of optical modes and introducing localized impurity modes. In addition, the sound velocities of both (In,Ga)N and Ga(N,P) display a nearly linear behavior as a function of substitution compositions. Supplementary material in the form of one pdf file available from the Journal web page at http://https://doi.org/10.1140/epjb/e2017-80481-0.

  14. Creep rupture testing of alloy 617 and A508/533 base metals and weldments.

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Li, M.; Soppet, W.K.; Rink, D.L. (Nuclear Engineering Division)

    2012-01-17

    The NGNP, which is an advanced HTGR concept with emphasis on both electricity and hydrogen production, involves helium as the coolant and a closed-cycle gas turbine for power generation with a core outlet/gas turbine inlet temperature of 750-1000 C. Alloy 617 is a prime candidate for VHTR structural components such as reactor internals, piping, and heat exchangers in view of its resistance to oxidation and elevated temperature strength. However, lack of adequate data on the performance of the alloy in welded condition prompted to initiate a creep test program at Argonne National Laboratory. In addition, Testing has been initiated to evaluate the creep rupture properties of the pressure vessel steel A508/533 in air and in helium environments. The program, which began in December 2009, was certified for quality assurance NQA-1 requirements during January and February 2010. Specimens were designed and fabricated during March and the tests were initiated in April 2010. During the past year, several creep tests were conducted in air on Alloy 617 base metal and weldment specimens at temperatures of 750, 850, and 950 C. Idaho National Laboratory, using gas tungsten arc welding method with Alloy 617 weld wire, fabricated the weldment specimens. Eight tests were conducted on Alloy 617 base metal specimens and nine were on Alloy 617 weldments. The creep rupture times for the base alloy and weldment tests were up to {approx}3900 and {approx}4500 h, respectively. The results showed that the creep rupture lives of weld specimens are much longer than those for the base alloy, when tested under identical test conditions. The test results also showed that the creep strain at fracture is in the range of 7-18% for weldment samples and were much lower than those for the base alloy, under similar test conditions. In general, the weldment specimens showed more of a flat or constant creep rate region than the base metal specimens. The base alloy and the weldment exhibited tertiary creep

  15. Hydrogen absorption/desorption properties in the TiCrV based alloys

    Directory of Open Access Journals (Sweden)

    A. Martínez

    2012-10-01

    Full Text Available Three different Ti-based alloys with bcc structure and Laves phase were studied. The TiCr1.1V0.9, TiCr1.1V0.45Nb0.45 and TiCr1.1V0.9 + 4%Zr7Ni10 alloys were melted in arc furnace under argon atmosphere. The hydrogen absorption capacity was measured by using aparatus type Sievert's. Crystal structures, and the lattice parameters were determined by using X-ray diffraction, XRD. Microestructural analysis was performed by scanning electron microscope, SEM and electron dispersive X-ray, EDS. The hydrogen storage capacity attained a value of 3.6 wt. (% for TiCr1.1V0.9 alloy in a time of 9 minutes, 3.3 wt. (% for TiCr1.1V0.45Nb0.45 alloy in a time of 7 minutes and 3.6 wt. (% TiCr1.1V0.9 + 4%Zr7Ni10 with an increase of the hydrogen absorption kinetics attained in 2 minutes. This indicates that the addition of Nb and 4%Zr7Ni10 to the TiCrV alloy acts as catalysts to accelerate the hydrogen absorption kinetics.

  16. Boundary Engineering for the Thermoelectric Performance of Bulk Alloys Based on Bismuth Telluride.

    Science.gov (United States)

    Mun, Hyeona; Choi, Soon-Mok; Lee, Kyu Hyoung; Kim, Sung Wng

    2015-07-20

    Thermoelectrics, which transports heat for refrigeration or converts heat into electricity directly, is a key technology for renewable energy harvesting and solid-state refrigeration. Despite its importance, the widespread use of thermoelectric devices is constrained because of the low efficiency of thermoelectric bulk alloys. However, boundary engineering has been demonstrated as one of the most effective ways to enhance the thermoelectric performance of conventional thermoelectric materials such as Bi2 Te3 , PbTe, and SiGe alloys because their thermal and electronic transport properties can be manipulated separately by this approach. We review our recent progress on the enhancement of the thermoelectric figure of merit through boundary engineering together with the processing technologies for boundary engineering developed most recently using Bi2 Te3 -based bulk alloys. A brief discussion of the principles and current status of boundary-engineered bulk alloys for the enhancement of the thermoelectric figure of merit is presented. We focus mainly on (1) the reduction of the thermal conductivity by grain boundary engineering and (2) the reduction of thermal conductivity without deterioration of the electrical conductivity by phase boundary engineering. We also discuss the next potential approach using two boundary engineering strategies for a breakthrough in the area of bulk thermoelectric alloys. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Mechanical properties of high carbon Fe{sub 3}Al-based intermetallic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Baligidad, R.G.; Radhakrishna, A.; Prakash, U. [Defence Metallurgical Research Lab., Hyderabad (India)

    1998-12-15

    Fe-16 wt% Al alloys containing 0.074 to 1.1 wt% carbon were prepared by a combination of air induction melting and electroslag remelting (ESR). The cast ESR ingots exhibited a two-phase structure consisting of Fe{sub 3}AlC{sub 0.5} precipitate in an Fe{sub 3}Al-based matrix. The precipitate volume fraction increased with increasing carbon content of the ingot. Most of the carbon was found to be present as the Fe{sub 3}AlC{sub 0.5} phase. The bulk hardness of these alloys increases linearly with increasing volume fraction of the precipitates. However, the Young`s modulus of these alloys was measured to be around 175 GPa and does not change significantly with change in volume fraction of the phases present. This is explained by arguing that both the matrix as well as precipitate exhibit the same modulus values for the alloys studied in the present work. Both the bulk hardness and Young`s modulus follow the rule of mixture for two phase alloys. However, the same may not be true for structure sensitive properties such as yield strength, ductility and creep resistance. (orig.) 18 refs.

  18. Experimental and Theoretical Investigation of Three Alloy 690 Mockup Components: Base Metal and Welding Induced Changes

    Directory of Open Access Journals (Sweden)

    Rickard R. Shen

    2014-01-01

    Full Text Available The stress corrosion cracking (SCC resistance of cold deformed thermally treated (TT Alloy 690 has been questioned in recent years. As a step towards understanding its relevancy for weld deformed Alloy 690 in operating plants, Alloy 690 base metal and heat affected zone (HAZ microstructures of three mockup components have been studied. All mockups were manufactured using commercial heats and welding procedures in order to attain results relevant to the materials in the field. Thermodynamic calculations were performed to add confidence in phase identification as well as understanding of the evolution of the microstructure with temperature. Ti(C,N banding was found in all materials. Bands with few large Ti(C,N precipitates had negligible effect on the microstructure, whereas bands consisting of numerous small precipitates were associated with locally finer grains and coarser M23C6 grain boundary carbides. The Ti(C,N remained unaffected in the HAZ while the M23C6 carbides were fully dissolved close to the fusion line. Cold deformed solution annealed Alloy 690 is believed to be a better representation of this region than cold deformed TT Alloy 690.

  19. Chemical durability and degradation mechanisms of HT9 based alloy waste forms with variable Zr content

    Energy Technology Data Exchange (ETDEWEB)

    Olson, L. N. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-10-30

    In Corrosion studies were undertaken on alloy waste forms that can result from advanced electrometallurgical processing techniques to better classify their durability and degradation mechanisms. The waste forms were based on the RAW3-(URe) composition, consisting primarily of HT9 steel and other elemental additions to simulate nuclear fuel reprocessing byproducts. The solution conditions of the corrosion studies were taken from an electrochemical testing protocol, and meant to simulate conditions in a repository. The alloys durability was examined in alkaline and acidic brines.

  20. Precipitation of TCP. Phases in Ni-base alloys with high chromium content

    Energy Technology Data Exchange (ETDEWEB)

    Pigrova, G.D. [Central Boiler and Turbine Institute, St. Petersburg (Russian Federation)

    2010-07-01

    The method of physical-chemical phase analysis has been used to investigate the structure, composition and amount of different phases for several commercial alloyed materials. Phase diagram in the temperature range 750-1100 C for high-temperature Ni-base alloy has been achieved. The main phase reactions during long-time ageing are carbide reaction MC{yields}M{sub 23}C{sub 6} and {sigma}-phase formation. The {sigma}-phase formation mechanism established shows that the process kinetics are also approximated by Johnson-Mell equation as it is in case of {sigma}-phase formation in stainless steels. (orig.)

  1. Anticorrosion properties of textured substrates made of copper-based binary alloys

    Science.gov (United States)

    Khlebnikova, Yu. V.; Suaridze, T. R.; Rodionov, D. P.; Egorova, L. Yu.; Gervas'eva, I. V.; Gulyaeva, R. I.

    2017-10-01

    The tendency of some copper-based binary alloys to oxidize has been studied by the thermogravimetry method. It has been established that, apart from their perfect cubic texture and the high strength properties, substrates made of the Cu-Ni, Cu-0.4% Cr, and Cu-1.6% Fe alloys also possess better anticorrosion properties at the temperature of the deposition of the epitaxial layers (700°C) than the substrates of pure copper. In the alloys containing disperse particles of a second phase, the oxidation resistance decreases in the inverse proportion to the particle size. The Cu-0.6% V ribbon, in which the vanadium particles reach a size of several microns, was even less resistant to oxidation than the copper substrate; therefore, it cannot be used for the deposition of functional layers at elevated temperatures.

  2. Nb-Based Nb-Al-Fe Alloys: Solidification Behavior and High-Temperature Phase Equilibria

    Science.gov (United States)

    Stein, Frank; Philips, Noah

    2017-09-01

    High-melting Nb-based alloys hold significant promise for the development of novel high-temperature materials for structural applications. In order to understand the effect of alloying elements Al and Fe, the Nb-rich part of the ternary Nb-Al-Fe system was investigated. A series of Nb-rich ternary alloys were synthesized from high-purity Nb, Al, and Fe metals by arc melting. Solidification paths were identified and the liquidus surface of the Nb corner of the ternary system was established by analysis of the as-melted microstructures and thermal analysis. Complementary analysis of heat-treated samples yielded isothermal sections at 1723 K and 1873 K (1450 °C and 1600 °C).

  3. Antimony Influence on Shape of Eutectic Silicium in Al-Si Based Alloys

    Directory of Open Access Journals (Sweden)

    Bolibruchová D.

    2017-12-01

    Full Text Available Liquid AI-Si alloys are usually given special treatments before they are cast to obtain finer or modified matrix and eutectic structures, leading to improved properties. For many years, sodium additions to hypoeutectic and eutectic AI-Si melts have been recognized as the most effective method of modifying the eutectic morphology, although most of the group IA or IIA elements have significant effects on the eutectic structure. Unfortunately, many of these approaches also have associated several founding difficulties, such as fading, forming dross in presence of certain alloying elements, reduced fluidity, etc. ln recent years, antimony additions to AI-Si castings have attracted considerable attention as an alternative method of refining the eutectic structure. Such additions eliminate many of the difficulties listed above and provide permanent (i.e. non-fading refining ability. In this paper, the authors summarize work on antimony treatment of Al-Si based alloys.

  4. Effect of aluminumion implantation on high temperature oxidation of nickel-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mitsuo, Atsushi (Tokyo Metropolitan Industrial Technology Center, 3-13-10 Nishigaoka, Kita-ku, Tokyo 115 (Japan)); Tanaki, Toshiyuki (Tokyo Metropolitan Industrial Technology Center, 3-13-10 Nishigaoka, Kita-ku, Tokyo 115 (Japan)); Shinozaki, Teruo (Japan Gas Appliances Inspection Association, 4-1-10 Azusawa, Itabashi-ku, Tokyo 174 (Japan)); Iwaki, Masaya (Institute of Physics and Chemical Research, 2-1 Hirosawa, Wako-shi, Saitama 350-01 (Japan))

    1994-08-01

    The thermal oxidation properties of Al-ion-implanted, Ni-based alloys used for thermocouples of Inconel 600, alumel, chromel and constantan have been studied in humid O[sub 2] atmospheres at 970K for 50h. The Al ion implantation was performed with doses ranging from 1x10[sup 16] to 2x10[sup 17] ioncm[sup -2] at an energy of 50keV. The depth profiles measured by Auger electron spectroscopy showed that the concentrations of Al and O were higher near the surface of the alloys after implantation. The implanted alumel and constantan exhibited no effect on the suppression of oxidation. However, implantation above a dose of 1x10[sup 17]Al ioncm[sup -2] significantly slowed the oxidation of the Inconel 600 and chromel alloys containing Cr. The thermoelectric properties of the actual thermocouples modified by Al ion implantation are discussed. ((orig.))

  5. Au-Ge based Candidate Alloys for High-Temperature Lead-Free Solder Alternatives

    DEFF Research Database (Denmark)

    Chidambaram, Vivek; Hald, John; Hattel, Jesper Henri

    2009-01-01

    Au-Ge based candidate alloys have been proposed as an alternative to high-lead content solders that are currently being used for high-temperature applications. The influence of the low melting point metals namely In, Sb and Sn to the Au-Ge eutectic with respect to the microstructure...... was primarily strengthened by the refined (Ge) dispersed phase. The distribution of phases played a relatively more crucial role in determining the ductility of the bulk solder alloy. In the present work it was found that among the low melting point metals, the addition of Sb to the Au-Ge eutectic would...... and microhardness has been extensively reported. Furthermore, the effects of thermal aging on the microstructure and its corresponding microhardness of these promising candidate alloys have been investigated in this work. After thermal aging at 200°C for different durations ranging from 1 day to 3 weeks...

  6. Tunable dimensional crossover and magnetocrystalline anisotropy in Fe2P -based alloys

    Science.gov (United States)

    Zhuravlev, I. A.; Antropov, V. P.; Vishina, A.; van Schilfgaarde, M.; Belashchenko, K. D.

    2017-10-01

    Electronic structure calculations are used to examine the magnetic properties of Fe2P -based alloys and the mechanisms through which the Curie temperature and magnetocrystalline anisotropy can be optimized for specific applications. It is found that at elevated temperatures the magnetic interaction in pure Fe2P develops a pronounced two-dimensional character due to the suppression of the magnetization in one of the sublattices, but the interlayer coupling is very sensitive to band filling and structural distortions. This feature suggests a natural explanation for the observed sharp enhancement of the Curie temperature by alloying with multiple elements, such as Co, Ni, Si, and B. The magnetocrystalline anisotropy is also tunable by electron doping, reaching a maximum near the electron count of pure Fe2P . These findings enable the optimization of the alloy content, suggesting coalloying of Fe2P with Co (or Ni) and Si as a strategy for maximizing the magnetocrystalline anisotropy at and above room temperature.

  7. Application of feal intermetallic phase matrix based alloys in the turbine components of a turbocharger

    Directory of Open Access Journals (Sweden)

    J. Cebulski

    2015-01-01

    Full Text Available This paper presents a possible application of the state-of-the-art alloys based on the FeAl intermetallic phases as materials for the manufacture of heat-proof turbine components in an automobile turbocharger. The research was aimed at determining the resistance to corrosion of Fe40Al5CrTiB alloy in a gaseous environment containing 9 % O2 + 0,2 % HCl + 0,08 % SO2 + N2. First the kinetics of corrosion processes for the considered alloy were determined at the temperatures of 900 °C, 1 000 °C and 1 100 °C, which was followed by validation under operating conditions. To do so, the tests were carried out over a distance of 20 000 km. The last stage involved examination of the surfaces after the test drive. The obtained results are the basis for further research in this field.

  8. Fuel behavior in severe accidents and Mo-alloy based cladding designs to improve accident tolerance

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Bo [Electric Power Research Institute, Palo Alto, CA (United States). Nucler Power Sector

    2013-03-15

    The severe accidents at TMI-2 and Fukushima-Daiichi led to core meltdown and hydrogen explosions. The main source of energy causing core melting is the decay heat from {beta}-, {beta}+, and {gamma} decays of short-lived isotopes following a power scram. The exothermic reaction of Zr-alloy cladding can further increase the cladding temperature leading to rapid cladding corrosion and hydrogen production. The most effective mitigation to minimize core damage in a severe accident is to extend the duration of heat removal capacity via battery-supported passive cooling for as long as practically possible. Replacing the Zr-alloy cladding with a higher heat resistant cladding with lower enthalpy release rate may also provide additional coping time for accident management. Such a heat resistant cladding may also overcome the current licensing concerns about Zr-alloy hydriding and post quench ductility issues in a design base loss of coolant accident (LOCA). Zr-alloy cladding, while has been optimized for normal operation in high pressure water and steam of light water reactors, will rapidly lose its corrosion resistance and tensile and creep strength in high pressure steam. Evaluation of alternate cladding materials and designs have been performed to search for a new fuel cladding design which will substantially improve the safety margins at elevated temperatures during a severe accident, while maintaining the excellent fuel performance attributes of the current Zr-alloy cladding. The screening criteria for the evaluation include neutronic properties, material availability, adaptability and operability in current LWRs, resistance to melting. The new designs also need to be fabricable, maintain sufficient strength and resist to attack by high pressure steam. Engineering metals, alloys and ceramics which can meet some or most of these requirements are limited. Following review of the properties of potential candidates, it is concluded that molybdenum alloys may potentially

  9. Advanced alumina composites reinforced with Nb-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, R.; Klassen, T.; Bormann, R. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Materialforschung; Dickau, B.; Bartels, A.; Bormann, R. [Dept. of Material Science and Technology, Technical Univ. Hamburg-Harburg, Hamburg (Germany); Gaertner, F. [Inst. of Mechanical Engineering, Univ. of the Federal Armed Forces, Hamburg (Germany)

    2002-03-01

    New (inter)metallic-ceramic composites for high-temperature structural and functional applications are prepared via high-energy ball milling of Nb, Al and Al{sub 2}O{sub 3}. During compaction by pressureless sintering, dense alumina aluminide alloys are formed that consist of interconnected networks of the ceramic and the (inter)metallic phases. Mechanical properties, wear resistance and resistivity measurements of the system Nb-Nb{sub 3}Al/Al{sub 2}O{sub 3} show that these composites have superior damage tolerance, i.e. high fracture toughnesses and bending strengths of about a factor 4 over monolithic Al{sub 2}O{sub 3}. The wear resistance has been determined to be in the range of galvanic Cr-coatings. Owing to the good wear resistance and the high damage tolerance, these composites are promising for automotive applications, such as valves or brake discs. (orig.)

  10. Morphology Evolution on the Fracture Surface and Fracture Mechanisms of Multiphase Nanostructured ZrCu-Base Alloys

    Directory of Open Access Journals (Sweden)

    Feng Qiu

    2017-03-01

    Full Text Available A multiphase nanostructured ZrCu-base bulk alloy which showed a unique microstructure consisting of sub-micrometer scale Zr2Cu solid solution, nano-sized twinned plate-like ZrCu martensite (ZrCu (M, and retained ZrCu (B2 austenite was fabricated by copper mold casting. The observation of periodic morphology evolution on the fracture surface of the multiphase nanostructured ZrCu-base alloys has been reported, which suggested a fluctuant local stress intensity along the crack propagation. It is necessary to investigate the compressive deformation behavior and the fracture mechanism of the multiphase alloy and the relation to the unique microstructures. The results obtained in this study provide a better understanding of the deformation and fracture mechanisms of multiphase hybrid nanostructured ZrCu-based alloys and give guidance on how to improve the ductility/toughness of bulk ZrCu-based alloys.

  11. The elemental move characteristic of nickel-based alloy in molten salt corrosion by using nuclear microprobe

    Science.gov (United States)

    Lei, Qiantao; Liu, Ke; Gao, Jie; Li, Xiaolin; Shen, Hao; Li, Yan

    2017-08-01

    Nickel-based alloys as candidate materials for Thorium Molten Salt Reactor (TMSR), need to be used under high temperature in molten salt environment. In order to ensure the safety of the reactor running, it is necessary to study the elemental move characteristic of nickel-based alloys in the high temperature molten salts. In this work, the scanning nuclear microprobe at Fudan University was applied to study the elemental move. The Nickel-based alloy samples were corroded by molten salt at different temperatures. The element concentrations in the Nickel-based alloys samples were determined by the scanning nuclear microprobe. Micro-PIXE results showed that the element concentrations changed from the interior to the exterior of the alloy samples after the corrosion.

  12. Modified calcium oxide as stable solid base catalyst for Aldol ...

    Indian Academy of Sciences (India)

    obtaining many fine chemicals of commercial interest. This kind of reaction can catalytically undergo in the presence of a strong base or acid in liquid phase.1–3. However, high operating costs and serious environmen- tal issues associated with product separation, purifi- cation, corrosion and waste generation attract great.

  13. ZnO-based semiconductors studied by Raman spectroscopy. Semimagnetic alloying, doping, and nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Schumm, Marcel

    2009-07-01

    ZnO-based semiconductors were studied by Raman spectroscopy and complementary methods (e.g. XRD, EPS) with focus on semimagnetic alloying with transition metal ions, doping (especially p-type doping with nitrogen as acceptor), and nanostructures (especially wet-chemically synthesized nanoparticles). (orig.)

  14. Laser cladding of Zr-based coating on AZ91D magnesium alloy for ...

    Indian Academy of Sciences (India)

    based coating made of Zr powder was fabricated on AZ91D magnesium alloy by laser cladding. The microstructure of the coating was characterized by XRD, SEM and TEM techniques. The wear resistance of the coating was evaluated under dry ...

  15. Performance Comparison of Steam-Based and Chromate Conversion Coatings on Aluminum Alloy 6060

    DEFF Research Database (Denmark)

    Din, Rameez Ud; Jellesen, Morten Stendahl; Ambat, Rajan

    2015-01-01

    In this study, oxide layers generated on aluminum alloy 6060(UNS A96060) using a steam-based process were compared with conventional chromate and chromate-phosphate conversion coatings. Chemical composition and microstructure of the conversion coatings were investigated and their corrosion perfor...

  16. Flaws Description in AlSi11 Alloy-Based Composite Fibres Reinforced Casts

    Directory of Open Access Journals (Sweden)

    Pędzich, Z.

    2007-01-01

    Full Text Available In the paper the application of different methods: profilography, atomic force microscopy, scanning electron microscopy and mercury porosimetry for description of flaws in composites based on AlSi11 (AK11 alloy with fibrous reinforcement is presented.

  17. Investigation of Martensite Formation in Fe Based Alloys During Heating From Boiling Nitrogen Temperature

    DEFF Research Database (Denmark)

    Villa, Matteo; Christiansen, Thomas L.; Hansen, Mikkel F.

    2015-01-01

    he austenite-to-martensite transformation at temperatures below room temperature was investigated in situ by magnetometry in Fe-N, Fe-Cr-C and Fe-Cr-Ni based alloys. After quenching to room temperature, samples were immersed in boiling nitrogen and martensite formation was followed during...

  18. Ambient-temperature high damping capacity in TiPd-based martensitic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Dezhen [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Zhou, Yumei, E-mail: zhouyumei@mail.xjtu.edu.cn [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Ding, Xiangdong [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Otsuka, Kazuhiro [Ferroic Physics Group, National Institute for Materials Science, Tsukuba 305-0047, Ibaraki (Japan); Lookman, Turab [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Sun, Jun [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Ren, Xiaobing [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Ferroic Physics Group, National Institute for Materials Science, Tsukuba 305-0047, Ibaraki (Japan)

    2015-04-24

    Shape memory alloys (SMAs) have attracted considerable attention for their high damping capacities. Here we investigate the damping behavior of Ti{sub 50}(Pd{sub 50−x}D{sub x}) SMAs (D=Fe, Co, Mn, V) by dynamic mechanical analysis. We find that these alloys show remarkably similar damping behavior. There exists a sharp damping peak associated with the B2–B19 martensitic transformation and a high damping plateau (Q{sup −1}~0.02–0.05) over a wide ambient-temperature range (220–420 K) due to the hysteretic twin boundary motion. After doping hydrogen into the above alloys, a new relaxation-type damping peak appears in the martensite phase over 270–360 K. Such a peak is considered to originate from the interaction of hydrogen atoms with twin boundaries and the corresponding damping capacity (Q{sup −1}~0.05–0.09) is enhanced by roughly twice that of the damping plateau for each alloy. Moreover, the relaxation peaks are at higher temperatures for the TiPd-based alloys (270–370 K) than for the TiNi-based alloys (190–260 K). We discuss the influence of hydrogen diffusion, mobility of twin boundaries and hydrogen–twin boundary interaction on the temperature range of the relaxation peak. Our results suggest that a martensite, with appropriate values for twinning shear and hydrogen doping level, provides a route towards developing high damping SMAs for applications in desired temperature ranges.

  19. Bioactive calcium phosphate coatings on metallic implants

    Science.gov (United States)

    Sedelnikova, M. B.; Komarova, E. G.; Sharkeev, Yu. P.; Tolkacheva, T. V.; Khlusov, I. A.; Sheikin, V. V.

    2017-09-01

    Biocomposites based on bioinert metals or alloys and bioactive calcium phosphate coatings are a promising tendency of the new-generation implants development. In recent years, the approach of regenerative medicine based on the use of biodegradable biomaterials has been priority direction. Such materials are capable of initiating the bone tissue regeneration and replaced by the newly formed bone. The microarc oxidation (MAO) method allows obtaining the bioactive coatings with a porous structure, special functional properties, and modified by the essential elements. During the last decade, the investigations in the field of the nanostructured biocomposites based on bioinert Ti, Zr, Nb and their alloys with a calcium phosphate coatings deposited by the MAO method have been studied in the Institute of Strength Physics and Materials Science SB RAS, Tomsk. In this article the possibility to produce the bioactive coatings with high antibacterial and osseoconductive properties due to the introduction in the coatings of Zn, Cu, Ag, La, Si elements and wollastonite CaSiO3 was shown. The high hydrophilic and bioresorbed coatings stimulate the processes of osseointegration of the implant into the bone tissue. A promising direction in the field of the medical material science is a development of the metallic implants with good biomechanical compatibility to the bone, such as Ti-Nb alloys with a low elastic modulus that can be classified as biomaterials of the second generation. Zr and its alloys are promising materials for the dentistry and orthopedic surgery due to their high strength and corrosion resistance. Biodegradable Mg alloys are biomaterials of third generation. Such materials can dissolve with a certain speed in human body and excreted from the body thereby excluding the need for reoperation. This article presents the analysis of the study results of bioactive MAO coatings on Ti, Ti-Nb, Zr-Nb and Mg alloys and their promising medical application.

  20. Surface treatments for controlling corrosion rate of biodegradable Mg and Mg-based alloy implants.

    Science.gov (United States)

    Uddin, M S; Hall, Colin; Murphy, Peter

    2015-10-01

    Due to their excellent biodegradability characteristics, Mg and Mg-based alloys have become an emerging material in biomedical implants, notably for repair of bone as well as coronary arterial stents. However, the main problem with Mg-based alloys is their rapid corrosion in aggressive environments such as human bodily fluids. Previously, many approaches such as control of alloying materials, composition and surface treatments, have been attempted to regulate the corrosion rate. This article presents a comprehensive review of recent research focusing on surface treatment techniques utilised to control the corrosion rate and surface integrity of Mg-based alloys in both in vitro and in vivo environments. Surface treatments generally involve the controlled deposition of thin film coatings using various coating processes, and mechanical surfacing such as machining, deep rolling or low plasticity burnishing. The aim is to either make a protective thin layer of a material or to change the micro-structure and mechanical properties at the surface and sub-surface levels, which will prevent rapid corrosion and thus delay the degradation of the alloys. We have organised the review of past works on coatings by categorising the coatings into two classes-conversion and deposition coatings-while works on mechanical treatments are reviewed based on the tool-based processes which affect the sub-surface microstructure and mechanical properties of the material. Various types of coatings and their processing techniques under two classes of coating and mechanical treatment approaches have been analysed and discussed to investigate their impact on the corrosion performance, biomechanical integrity, biocompatibility and cell viability. Potential challenges and future directions in designing and developing the improved biodegradable Mg/Mg-based alloy implants were addressed and discussed. The literature reveals that no solutions are yet complete and hence new and innovative approaches are

  1. Microcontroller-based system for estimate of calcium in serum samples.

    Science.gov (United States)

    Neelamegam, Periyaswmy; Jamaludeen, Abdul Sheriff; Ragendran, Annamalai; Murugrananthan, Krishanamoorthy

    2010-01-01

    In this study, a microcontroller-based control unit was designed and constructed for the estimation of serum calcium in blood samples. The proposed optoelectronic instrument used a red light emitting diode (LED) as a light source and photodiode as a sensor. The performance of the system was compared with that of a commercial instrument in measuring calcium ion. The quantitative analysis of calcium in a catalyst using arsenazo III as colorimetric reagent was used to test the device. The calibration curve for calcium binding with arsenazo III was drawn to check the range of linearity, which was between 0.1 to 4.5 mM L⁻¹. The limit of detection (LOD) is 0.05 mM L⁻¹. Absorbance changes over the pH range of 2-12 were determined to optimize the assay, with maximum absorption at pH 9.0. Interferences in absorbance from monovalent (K+ and Na+) and divalent (Mg²+) cations were also studied. The results show that the system works successfully.

  2. Quaternary alloys based on II-VI semiconductors

    CERN Document Server

    Tomashyk, Vasyl

    2014-01-01

    Systems Based on ZnSSystems Based on ZnSeSystems Based on ZnTeSystems Based on CdSSystems Based on CdSeSystems Based on CdTeSystems Based on HgSSystems Based on HgSeSystems Based on HgTeIndexReferences appear at the end of each chapter.

  3. Room temperature deformation of in-situ grown quasicrystals embedded in Al-based cast alloy

    Directory of Open Access Journals (Sweden)

    Boštjan Markoli

    2013-12-01

    Full Text Available An Al-based cast alloy containing Mn, Be and Cu has been chosen to investigate the room temperature deformation behavior of QC particles embedded in Al-matrix. Using LOM, SEM (equipped with EDS, conventional TEM with SAED and controlled tensile and compression tests, the deformation response of AlMn2Be2Cu2 cast alloy at room temperature has been examined. Alloy consisted of Al-based matrix, primary particles and eutectic icosahedral quasicrystalline (QC i-phase and traces of Θ-Al2Cu and Al10Mn3. Tensile and compression specimens were used for evaluation of mechanical response and behavior of QC i-phase articles embedded in Al-cast alloy. It has been established that embedded QC i-phase particles undergo plastic deformation along with the Al-based matrix even under severe deformation and have the response resembling that of the metallic materials by formation of typical cup-and-cone feature prior to failure. So, we can conclude that QC i-phase has the ability to undergo plastic deformation along with the Al-matrix to greater extent contrary to e.g. intermetallics such as Θ-Al2Cu for instance.

  4. Design of lead-free candidate alloys for high-temperature soldering based on the Au–Sn system

    DEFF Research Database (Denmark)

    Chidambaram, Vivek; Hattel, Jesper Henri; Hald, John

    2010-01-01

    of the Au–Sn binary system were explored in this work. Furthermore, the effects of thermal aging on the microstructure and microhardness of these promising Au–Sn based ternary alloys were investigated. For this purpose, the candidate alloys were aged at a lower temperature, 150°C for up to 1week...

  5. Microstructure of rapidly solidified Nb-based pre-alloyed powders for additive manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yueling; Jia, Lina, E-mail: jialina@buaa.edu.cn; Kong, Bin; Zhang, Shengnan; Zhang, Fengxiang; Zhang, Hu

    2017-07-01

    Highlights: • Sphere shaped Nb-37Ti-13Cr-2Al-1Si pre-alloyed powders were prepared by PREP. • An oxide layer with a thickness of 9.39 nm was generated on the powder surface. • The main phases of the pre-alloyed powders were Nbss and Cr{sub 2}Nb. • SDAS increased and microhardness decreased with the increase of powder size. • Microstructure of powders evolved into large grains from dendrite structures after HT. - Abstract: For powder-based additive manufacturing, sphere-shaped Nb-37Ti-13Cr-2Al-1Si pre-alloyed powders were prepared by plasma rotating electrode processing (PREP). The microstructure, surface oxidation and microhardness of the pre-alloyed powders were systematically investigated. Results showed that the main phases were Nb solid solution (Nbss) and Cr{sub 2}Nb. The Cr{sub 2}Nb phases were further determined using transmission electron microscopy (TEM). Fine dendrite structures were observed in the as-fabricated pre-alloyed powders, which transformed to large grains after heat treatment (HT) at 1450 °C for 3 h. With the increase of powder size, the secondary dendrite arm spacing (SDAS) increased and the microhardness (HV) decreased. A clean powder surface free of oxide particles was obtained by PREP and an oxide layer with 9.39 nm in thickness was generated on the powder surface. Compared with Cr- and Nb-oxides, more Ti-oxides were formed on outmost powder surface with a higher content of Ti (up to 47.86 at.%). The differences upon the microstructure and microhardness of the pre-alloyed powders with different sizes were discussed.

  6. Effect of sound on gap-junction-based intercellular signaling: Calcium waves under acoustic irradiation.

    Science.gov (United States)

    Deymier, P A; Swinteck, N; Runge, K; Deymier-Black, A; Hoying, J B

    2015-01-01

    We present a previously unrecognized effect of sound waves on gap-junction-based intercellular signaling such as in biological tissues composed of endothelial cells. We suggest that sound irradiation may, through temporal and spatial modulation of cell-to-cell conductance, create intercellular calcium waves with unidirectional signal propagation associated with nonconventional topologies. Nonreciprocity in calcium wave propagation induced by sound wave irradiation is demonstrated in the case of a linear and a nonlinear reaction-diffusion model. This demonstration should be applicable to other types of gap-junction-based intercellular signals, and it is thought that it should be of help in interpreting a broad range of biological phenomena associated with the beneficial therapeutic effects of sound irradiation and possibly the harmful effects of sound waves on health.

  7. Influence of alloy elements (Mo, Nb, Ti) on the strength and damping capacity of Fe-Cr based alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hui, E-mail: yinchanggeng5525@163.com [Science and Technology on Surface Physics and Chemistry Laboratory, P.O. Box No. 9-35, Huafengxincun, Jiangyou City, Sichuan Province 621908 (China); National Key Laboratory for Nuclear Fuel and Materials, Nuclear Power Institute of China, Chengdu 610041 (China); Wang, Fu [School of Material Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, Sichuan (China); Liu, Haitao [State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang, 110819 (China); Pan, Dong; Pan, Qianfu; Liu, Yunming; Xiao, Jun [National Key Laboratory for Nuclear Fuel and Materials, Nuclear Power Institute of China, Chengdu 610041 (China); Zhang, Pengcheng [Science and Technology on Surface Physics and Chemistry Laboratory, P.O. Box No. 9-35, Huafengxincun, Jiangyou City, Sichuan Province 621908 (China)

    2016-06-14

    Effects of Mo-, Ti- and Nb-substitution for Al on the strength and damping capacity of the Fe-13Cr-4.5Al alloy were investigated by analyzing the mutual relationships among microstructures, strength, internal stress and damping capacity of the alloys. The obtained results show that the substitution of 0.5Mo for 0.5Al improves both the strength and damping capacity of the alloy. While the substitution of 0.5Ti or 0.5Nb for 0.5Al simply improves the strength but reduces the damping capacity of the alloy. The effect of the alloy elements on the strength and damping capacity lies in the fact that the substitution of the alloy elements generates both local internal stress and pin dislocations. Lower average internal stress leads to higher damping capacity of the alloy. The substitution of 0.5Mo for 0.5Al decreases the interactions between the dislocations and the solute atoms while increases the elastic distortions of the crystalline lattice, resulting in the enhancement of both strength and damping capacity.

  8. Electrochemical studies of calcium chloride-based molten salt systems

    Energy Technology Data Exchange (ETDEWEB)

    Blanchard, Jr., Thomas P. [Univ. of Tennessee, Knoxville, TN (United States)

    1992-12-01

    Conductance and EMF studies of CaCl2-based melts were performed in the temperature range 790--990 C. Conductivity data collected using magnesia tubes and capillaries showed deviations from the data recommended by the National Bureau of Standards. These deviations are attributed to the slow dissolution of magnesia by the CaCl2-CaO melt. Conductivity data for molten CaCl2 using a pyrolytic boron nitride capillary were in reasonable agreement with the recommended data; however, undissolved CaO in CaCl2 may have caused blockage of the pyrolytic boron nitride capillary, resulting in fluctuations in the measured resistance. The utility of the AgCl/Ag reference electrode in CaCl2-AgCl and CaCl2-CaO-AgCl melts, using asbestos diaphragms and Vycor glass as reference half-cell membranes, was also investigated. Nernstian behavior was observed using both types of reference half-cell membranes in CaCl2-AgCl melts. The AgCl/Ag reference electrode also exhibited Nernstian behavior in CaCl2-CaO-AgCl melts using a Vycor reference half-cell membrane and a magnesia crucible. The use of CaCl2 as a solvent is of interest since it is used in plutonium metal purification, as well as various other commercial applications. 97 refs., 33 figs., 13 tabs.

  9. Cytotoxicity and genotoxicity of calcium silicate-based cements on an osteoblast lineage

    Directory of Open Access Journals (Sweden)

    Ana Lívia GOMES-CORNÉLIO

    2016-01-01

    Full Text Available Abstract Several calcium silicate-based biomaterials have been developed in recent years, in addition to Mineral Trioxide Aggregate (MTA. The aim of this study was to evaluate the cytotoxicity, genotoxicity and apoptosis/necrosis in human osteoblast cells (SAOS-2 of pure calcium silicate-based cements (CSC and modified formulations: modified calcium silicate-based cements (CSCM and three resin-based calcium silicate cements (CSCR1 (CSCR 2 (CSCR3. The following tests were performed after 24 hours of cement extract exposure: methyl-thiazolyl tetrazolium (MTT, apoptosis/necrosis assay and comet assay. The negative control (CT- was performed with untreated cells, and the positive control (CT+ used hydrogen peroxide. The data for MTT and apoptosis were submitted to analysis of variance and Bonferroni’s posttest (p < 0.05, and the data for the comet assay analysis, to the Kruskal-Wallis and Dunn tests (p < 0.05. The MTT test showed no significant difference among the materials in 2 mg/mL and 10 mg/mL concentrations. CSCR3 showed lower cell viability at 10 mg/mL. Only CSC showed lower cell viability at 50 mg/mL. CSCR1, CSCR2 and CSCR3 showed a higher percentage of initial apoptosis than the control in the apoptosis test, after 24 hours exposure. The same cements showed no genotoxicity in the concentration of 2 mg/mL, with the comet assay. CSC and CSCR2 were also not genotoxic at 10 mg/mL. All experimental materials showed viability with MTT. CSC and CSCR2 presented a better response to apoptosis and genotoxicity evaluation in the 10 mg/mL concentration, and demonstrated a considerable potential for use as reparative materials.

  10. Fatigue Strength Estimation Based on Local Mechanical Properties for Aluminum Alloy FSW Joints.

    Science.gov (United States)

    Sillapasa, Kittima; Mutoh, Yoshiharu; Miyashita, Yukio; Seo, Nobushiro

    2017-02-15

    Overall fatigue strengths and hardness distributions of the aluminum alloy similar and dissimilar friction stir welding (FSW) joints were determined. The local fatigue strengths as well as local tensile strengths were also obtained by using small round bar specimens extracted from specific locations, such as the stir zone, heat affected zone, and base metal. It was found from the results that fatigue fracture of the FSW joint plate specimen occurred at the location of the lowest local fatigue strength as well as the lowest hardness, regardless of microstructural evolution. To estimate the fatigue strengths of aluminum alloy FSW joints from the hardness measurements, the relationship between fatigue strength and hardness for aluminum alloys was investigated based on the present experimental results and the available wide range of data from the references. It was found as: σa (R = -1) = 1.68 HV (σa is in MPa and HV has no unit). It was also confirmed that the estimated fatigue strengths were in good agreement with the experimental results for aluminum alloy FSW joints.

  11. Solid particle erosion of steels and nickel based alloys candidates for USC steam turbine blading

    Energy Technology Data Exchange (ETDEWEB)

    Cernuschi, Federico; Guardamagna, Cristina; Lorenzoni, Lorenzo [ERSE SpA, Milan (Italy); Robba, Davide [CESI, Milan (Italy)

    2010-07-01

    The main objective of COST536 Action is to develop highly efficient steam power plant with low emissions, from innovative alloy development to validation of component integrity. In this perspective, to improve the operating efficiency, materials capable of withstanding higher operating temperatures are required. For the manufacturing of components for steam power plants with higher efficiency steels and nickel-based alloys with improved oxidation resistance and creep strength at temperature as high as 650 C - 700 C have to be developed. Candidate alloys for manufacturing high pressure steam turbine diaphragms, buckets, radial seals and control valves should exhibit, among other properties, a good resistance at the erosion phenomena induced by hard solid particles. Ferric oxide (magnetite) scales cause SPE by exfoliating from boiler tubes and steam pipes (mainly super-heaters and re-heaters) and being transported within the steam flow to the turbine. In order to comparatively study the erosion behaviour of different materials in relatively short times, an accelerated experimental simulation of the erosion phenomena must be carried out. Among different techniques to induce erosion on material targets, the use of an air jet tester is well recognised to be one of the most valid and reliable. In this work the results of SPE comparative tests performed at high temperatures (550 C, 600 C and 650 C) at different impaction angles on some steels and nickel based alloys samples are reported. (orig.)

  12. Fatigue Strength Estimation Based on Local Mechanical Properties for Aluminum Alloy FSW Joints

    Directory of Open Access Journals (Sweden)

    Kittima Sillapasa

    2017-02-01

    Full Text Available Overall fatigue strengths and hardness distributions of the aluminum alloy similar and dissimilar friction stir welding (FSW joints were determined. The local fatigue strengths as well as local tensile strengths were also obtained by using small round bar specimens extracted from specific locations, such as the stir zone, heat affected zone, and base metal. It was found from the results that fatigue fracture of the FSW joint plate specimen occurred at the location of the lowest local fatigue strength as well as the lowest hardness, regardless of microstructural evolution. To estimate the fatigue strengths of aluminum alloy FSW joints from the hardness measurements, the relationship between fatigue strength and hardness for aluminum alloys was investigated based on the present experimental results and the available wide range of data from the references. It was found as: σa (R = −1 = 1.68 HV (σa is in MPa and HV has no unit. It was also confirmed that the estimated fatigue strengths were in good agreement with the experimental results for aluminum alloy FSW joints.

  13. Deformation behavior of NiAl-based alloys containing iron, cobalt, and hafnium

    Science.gov (United States)

    Pank, D. R.; Koss, D. A.; Nathal, M. V.

    1989-01-01

    The effects of alloying additions on the mechanical properties of the B2 intermetallic NiAl have been investigated in both the melt-spun ribbon and consolidated, bulk form. The study is based on a matrix of NiAl-based alloys with up to 20 at. pct Co and Fe additions and with reduced Al levels in the range of 30-40 at. pct. Characterization of the melt-spun ribbon by optical and scanning electron microscopy indicates a range of microstructures, including single-phase beta, gamma-prime necklace phase surrounding either martensitic or beta grains, and a mixture of equiaxed martensitic and gamma-prime grains. Bend ductility is present in melt-spun and annealed ribbons exhibiting the gamma-prime necklace structure and in a single-phase beta material containing 20 at. pct Fe. The analysis of compressive flow behavior on consolidated, bulk specimens indicates that the single-phase beta alloys exhibit a continuous decrease in yield stress with increasing temperature and profuse microcracking at grain boundaries. In contrast, multiphase (gamma-prime + either martensite or beta) alloys tend to display a peak in flow stress between 600 and 800 K, with little or no signs of microcracking. In general, heat treatments which convert the martensitic grains to beta + gamma-prime result in improved strength at temperatures above 600 K and better resistance to crack initiation.

  14. A dislocation density based micromechanical constitutive model for Sn-Ag-Cu solder alloys

    Science.gov (United States)

    Liu, Lu; Yao, Yao; Zeng, Tao; Keer, Leon M.

    2017-10-01

    Based on the dislocation density hardening law, a micromechanical model considering the effects of precipitates is developed for Sn-Ag-Cu solder alloys. According to the microstructure of the Sn-3.0Ag-0.5Cu thin films, intermetallic compounds (IMCs) are assumed as sphere particles embedded in the polycrystalline β-Sn matrix. The mechanical behavior of polycrystalline β-Sn matrix is determined by the elastic-plastic self-consistent method. The existence of IMCs not only impedes the motion of dislocations but also increases the overall stiffness. Thus, a dislocation density based hardening law considering non-shearable precipitates is adopted locally for single β-Sn crystal, and the Mori-Tanaka scheme is applied to describe the overall viscoplastic behavior of solder alloys. The proposed model is incorporated into finite element analysis and the corresponding numerical implementation method is presented. The model can describe the mechanical behavior of Sn-3.0Ag-0.5Cu and Sn-1.0Ag-0.5Cu alloys under high strain rates at a wide range of temperatures. Furthermore, the overall Young’s modulus changes due to different contents of IMCs is predicted and compared with experimental data. Results show that the proposed model can describe both elastic and inelastic behavior of solder alloys with reasonable accuracy.

  15. The electronic mechanism of the gamma/gamma' interface strength of Ir-based alloys

    CERN Document Server

    Chen, K; Tse, J S

    2002-01-01

    The electronic structures of the gamma/gamma' interface for two-phase Ir-based alloys (Ir/Ir sub 3 Ta and Ir/Ir sub 3 Ti) have been investigated by performing first-principles quantum mechanics DMol3 (a type of density functional theory for molecules) calculations. The Mayer bond order (MBO) is used to represent the shear and cohesion strengths of the interface by a local sum of the horizontal and vertical MBOs. By comparison with those for single-crystal Ir, the results show that both the cohesive and shear strengths of the gamma/gamma' interface for the Ir/Ir sub 3 Ta alloy increase. The cohesive strength of the interface for the Ir/Ir sub 3 Ti alloy increases, whereas the shear strength of the interface for Ir/Ir sub 3 Ti decreases. The electron charge density, the Hirshfeld charge, and orbital charge transfers are also calculated and analysed. An electronic mechanism for the gamma/gamma' interface strength of Ir-based alloys is then suggested.

  16. Modeling of self-controlling hyperthermia based on nickel alloy ferrofluids: Proposition of new nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Delavari, H. Hamid, E-mail: Hamid.delavari@gmail.com [Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Azadi Avenue, 145888-9694 Tehran (Iran, Islamic Republic of); Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala (Sweden); Madaah Hosseini, Hamid R. [Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Azadi Avenue, 145888-9694 Tehran (Iran, Islamic Republic of); Department of Materials Science and Engineering, Sharif University of Technology, Azadi Avenue, 145888-9694 Tehran (Iran, Islamic Republic of); Wolff, Max, E-mail: Max.wolff@physics.uu.se [Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala (Sweden)

    2013-06-15

    In order to provide sufficient heat without overheating healthy tissue in magnetic fluid hyperthermia (MFH), a careful design of the magnetic properties of nanoparticles is essential. We perform a systematic calculation of magnetic properties of Ni-alloy nanoparticles. Stoner–Wohlfarth model based theories (SWMBTs) are considered and the linear response theory (LRT) is used to extract the hysteresis loop of nickel alloy nanoparticles in alternating magnetic fields. It is demonstrated that in the safe range of magnetic field intensity and frequency the LRT cannot be used for the calculation of the area in the hysteresis for magnetic fields relevant for hyperthermia. The best composition and particle size for self-controlling hyperthermia with nickel alloys is determined based on SWMBTs. It is concluded that Ni–V and Ni–Zn are good candidates for self-controlling hyperthermia. - Highlights: ► Systematic calculation of magnetic properties of Ni-alloy NPs with composition has been performed. ► Optimum composition and particle size for self-controlling hyperthermia (SCH) have been determined. ► Ni–V and Ni–Zn nanoparticles are more appropriate candidates for SCH.

  17. Fatigue Strength Estimation Based on Local Mechanical Properties for Aluminum Alloy FSW Joints

    Science.gov (United States)

    Sillapasa, Kittima; Mutoh, Yoshiharu; Miyashita, Yukio; Seo, Nobushiro

    2017-01-01

    Overall fatigue strengths and hardness distributions of the aluminum alloy similar and dissimilar friction stir welding (FSW) joints were determined. The local fatigue strengths as well as local tensile strengths were also obtained by using small round bar specimens extracted from specific locations, such as the stir zone, heat affected zone, and base metal. It was found from the results that fatigue fracture of the FSW joint plate specimen occurred at the location of the lowest local fatigue strength as well as the lowest hardness, regardless of microstructural evolution. To estimate the fatigue strengths of aluminum alloy FSW joints from the hardness measurements, the relationship between fatigue strength and hardness for aluminum alloys was investigated based on the present experimental results and the available wide range of data from the references. It was found as: σa (R = −1) = 1.68 HV (σa is in MPa and HV has no unit). It was also confirmed that the estimated fatigue strengths were in good agreement with the experimental results for aluminum alloy FSW joints. PMID:28772543

  18. Optical modeling of nickel-base alloys oxidized in pressurized water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Clair, A. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS, Universite de Bourgogne, 9 avenue Alain Savary, BP 47870, 21078 Dijon cedex (France); Foucault, M.; Calonne, O. [Areva ANP, Centre Technique Departement Corrosion-Chimie, 30 Bd de l' industrie, BP 181, 71205 Le Creusot (France); Finot, E., E-mail: Eric.Finot@u-bourgogne.fr [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS, Universite de Bourgogne, 9 avenue Alain Savary, BP 47870, 21078 Dijon cedex (France)

    2012-10-01

    The knowledge of the aging process involved in the primary water of pressurized water reactor entails investigating a mixed growth mechanism in the corrosion of nickel-base alloys. A mixed growth induces an anionic inner oxide and a cationic diffusion parallel to a dissolution-precipitation process forms the outer zone. The in situ monitoring of the oxidation kinetics requires the modeling of the oxide layer stratification with the full knowledge of the optical constants related to each component. Here, we report the dielectric constants of the alloys 600 and 690 measured by spectroscopic ellipsometry and fitted to a Drude-Lorentz model. A robust optical stratification model was determined using focused ion beam cross-section of thin foils examined by transmission electron microscopy. Dielectric constants of the inner oxide layer depleted in chromium were assimilated to those of the nickel thin film. The optical constants of both the spinels and extern layer were determined. - Highlights: Black-Right-Pointing-Pointer Spectroscopic ellipsometry of Ni-base alloy oxidation in pressurized water reactor Black-Right-Pointing-Pointer Measurements of the dielectric constants of the alloys Black-Right-Pointing-Pointer Optical simulation of the mixed oxidation process using a three stack model Black-Right-Pointing-Pointer Scattered crystallites cationic outer layer; linear Ni-gradient bottom layer Black-Right-Pointing-Pointer Determination of the refractive index of the spinel and the Cr{sub 2}O{sub 3} layers.

  19. High-Throughput Study of Diffusion and Phase Transformation Kinetics of Magnesium-Based Systems for Automotive Cast Magnesium Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Alan A [The Ohio State Univ., Columbus, OH (United States); Zhao, Ji-Cheng [The Ohio State Univ., Columbus, OH (United States); Riggi, Adrienne [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Joost, William [US Dept. of Energy, Washington, DC (United States)

    2017-10-02

    The objective of the proposed study is to establish a scientific foundation on kinetic modeling of diffusion, phase precipitation, and casting/solidification, in order to accelerate the design and optimization of cast magnesium (Mg) alloys for weight reduction of U.S. automotive fleet. The team has performed the following tasks: 1) study diffusion kinetics of various Mg-containing binary systems using high-throughput diffusion multiples to establish reliable diffusivity and mobility databases for the Mg-aluminum (Al)-zinc (Zn)-tin (Sn)-calcium (Ca)-strontium (Sr)-manganese (Mn) systems; 2) study the precipitation kinetics (nucleation, growth and coarsening) using both innovative dual-anneal diffusion multiples and cast model alloys to provide large amounts of kinetic data (including interfacial energy) and microstructure atlases to enable implementation of the Kampmann-Wagner numerical model to simulate phase transformation kinetics of non-spherical/non-cuboidal precipitates in Mg alloys; 3) implement a micromodel to take into account back diffusion in the solid phase in order to predict microstructure and microsegregation in multicomponent Mg alloys during dendritic solidification especially under high pressure die-casting (HPDC) conditions; and, 4) widely disseminate the data, knowledge and information using the Materials Genome Initiative infrastructure (http://www.mgidata.org) as well as publications and digital data sharing to enable researchers to identify new pathways/routes to better cast Mg alloys.

  20. The effect of addition of various elements on properties of NiTi-based shape memory alloys for biomedical application

    Science.gov (United States)

    Kök, Mediha; Ateş, Gonca

    2017-04-01

    In biomedical applications, NiTi and NiTi-based alloys that show their shape memory effects at body temperature are preferred. In this study, the purpose is to produce NiTi and NiTi-based alloys with various chemical rates and electron concentrations and to examine their various physical properties. N45Ti55, Ni45Ti50Cr2.5Cu2.5, Ni48Ti51X (X=Mn, Sn, Co) alloys were produced in an arc melter furnace in this study. After the homogenization of these alloys, the martensitic phase transformation temperatures were determined with differential-scanner calorimeter. The transformation temperature was found to be below the 37 ° C (body temperature) in Ni45Ti50Cr2.5Cu2.5, Ni48Ti51X (X=Mn, Co) alloys; and the transformation temperature of the N45Ti55, Ni48Ti51Sn alloys was found to be over 37 ° C . Then, the micro and crystal structure analyses of the alloys were made, and it was determined that Ni45Ti50Cr2.5Cu2.5, Ni48Ti51X (X=Mn, Co) alloys, which were in austenite phase at room temperature, included B2 (NiTi) phase and Ti2Ni precipitation phase, and the alloys that were in the martensite phase at room temperature included B19ı (NiTi) phase and Ti2Ni phase. The common phase in both alloy groups is the Ti2Ni phase, and this type of phase is generally seen in NiTi alloys that are rich in titanium (Ti-rich).

  1. [A experimental study on the effect of fluorine capture of calcium based coal briquette].

    Science.gov (United States)

    Yang, Jiaolan; Chen, Dongqing; Jin, Xin; Zhao, Bingcheng; Ying, Bo; Wang, Shuquan; Li, Shengda; Yang, Cuifu

    2009-11-01

    To study on the fluorine capture effect of calcium based coal briquette with fluorine capture additive in coal-burning fluorosis area. Add proper proportions of calcium based fluorine capture additive in high fluorine coal for making coal briquette were added, and were added the fluorine in coal cinder in order to reduce its emission. Meanwhile, to determine the composes of coal briquette were added, the percentage of fluorine in coal cinder and the concentration of fluoride, sulfur dioxide and PM10 were determinated, to evaluate the effect of fluorine capture and the level of door air pollution. After pilot-scale studying on the effect of fluorine capture in 30 households at coal-burning fluorosis area in Guiding of Guizhou Province. The average fluorine capture rate were 71.8%, and the average concentration of fluoride were 0.0052 mg/m3, which reduces by 27.8% in comparison with control group and were lower than environmental air quality standard (0.007 mg/m3); and the average concentration of SO2 were 0.67 mg/m3, which reduces 52.8% in comparison with control group and slightly higher than those of indoor air quality standard (0.5 mg/m3). The application of the coal briquette made by calcium based fluorine capture additive could reduce the pollution caused by high fluorine coal, could improve the quality of indoor air.

  2. Synthesis and Characterization of Cockle Shell-Based Calcium Carbonate Aragonite Polymorph Nanoparticles with Surface Functionalization

    Directory of Open Access Journals (Sweden)

    Syairah Liyana Mohd Abd Ghafar

    2017-01-01

    Full Text Available The development of cockle shell-based calcium carbonate aragonite polymorph nanoparticle synthesis method using the technique of mechanical stirring in the presence of dodecyl dimethyl betaine (BS-12 incorporated with surface functionalization demonstrated high homogeneity of sample product with good nanoparticles dispersion. The cockle shell-based calcium carbonate aragonite nanoparticle with functionalized surface was characterized using transmission electron microscopy (TEM, field emission scanning electron microscopy (FESEM, particle size distribution, pH measurement analysis, Fourier Transform Infrared (FTIR spectroscopy, and X-ray diffraction (XRD. Surface functionalization was proven to improve the overall size and shape of the nanoparticles and enhance their dispersion properties, preventing coarse agglomeration among nanoparticles in general. The improved method was verified to retain its aragonite crystalline nature. Additionally, surface functionalization did not increase the size of nanoparticles throughout the modification process. This facile preparation using naturally occurring cockle shells as the main source is environmentally friendly because it provides relatively low cost of raw material source as it is abundantly available in nature and has good mineral purity content. Hence, high quality production of surface functionalized cockle shell-based calcium carbonate aragonite polymorph nanoparticles can potentially be exploited and produced on a large scale for various industrial applications, especially for biomedical purposes in the near future.

  3. Cell response of calcium phosphate based ceramics, a bone substitute material

    Directory of Open Access Journals (Sweden)

    Juliana Marchi

    2013-01-01

    Full Text Available The aim of this study was to characterize calcium phosphate ceramics with different Ca/P ratios and evaluate cell response of these materials for use as a bone substitute. Bioceramics consisting of mixtures of hydroxyapatite (HAp and β-tricalcium phosphate (β-TCP powders in different proportions were pressed and sintered. The physical and chemical properties of these bioceramics were then characterized. Characterization of the biological properties of these materials was based on analysis of cell response using cultured fibroblasts. The number of cells attached to the samples was counted from SEM images of samples exposed to cell culture solution for different periods. These data were compared by analysis of variance (ANOVA complemented by the Tukey's test. The TCP sample had higher surface roughness and lower density. The adherence and growth of FMM1 cells on samples from all groups was studied. Even though the different calcium based ceramics exhibited properties which made them suitable as bone substitutes, those with higher levels of β-TCP revealed improved cell growth on their surfaces. These observations indicated two-phase calcium phosphate based materials with a β-TCP surface layer to be a promising bone substitute.

  4. Alloying effects of refractory elements in the dislocation of Ni-based single crystal superalloys

    Directory of Open Access Journals (Sweden)

    Shiyu Ma

    2016-12-01

    Full Text Available The alloying effects of W, Cr and Re in the [100] (010 edge dislocation cores (EDC of Ni-based single crystal superalloys are investigated using first-principles based on the density functional theory (DFT. The binding energy, Mulliken orbital population, density of states, charge density and radial distribution functions are discussed, respectively. It is clearly demonstrated that the addition of refractory elements improves the stability of the EDC systems. In addition, they can form tougher bonds with their nearest neighbour (NN Ni atoms, which enhance the mechanical properties of the Ni-based single crystal superalloys. Through comparative analysis, Cr-doped system has lower binding energy, and Cr atom has evident effect to improve the systemic stability. However, Re atom has the stronger alloying effect in Ni-based single crystal superalloys, much more effectively hindering dislocation motion than W and Cr atoms.

  5. Microstructure and Mechanical Properties of Wide-gap Brazed Joints of K465 Alloy Using Cobalt-base Brazing Alloy

    Directory of Open Access Journals (Sweden)

    PAN Hui

    2017-06-01

    Full Text Available Vacuum brazing of K465 superalloy was carried out by using Co45NiCrWB cobalt-base filler metal at 1220 ℃ for different holding time, and the joint clearance was 0.5 mm pre-filled with FGH95 nickel-base superalloy powder. The effect of the structural constitution of brazed different holding time of temperature on the brazed joint microstructure and properties. The results show that the brazing seam is composed of alloy powder particles and borides among them. It is two-phase structure of γ and γ' with a few small blocks of borides in the powder particles, and there exists phases rich in Cr, W and Nb elements. The powder particles are growing along the holding time during the brazing process, while their combination is expanded. It is good for stress rapture properties of joints that borides was fine in brazing seam with more superalloy powder and proper holding time. And the joints brazed for 30-60 min show higher stress rapture properties.

  6. Densification behavior, nanocrystallization, and mechanical properties of spark plasma sintered Fe-based bulk amorphous alloys

    Science.gov (United States)

    Singh, Ashish Kumar

    Fe-based amorphous alloys are gaining increasing attention due to their exceptional wear and corrosion resistance for potential structural applications. Two major challenges that are hindering the commercialization of these amorphous alloys are difficulty in processing of bulk shapes (diameter > 10 mm) and lack of ductility. Spark plasma sintering (SPS) is evolving as a promising technique for processing bulk shapes of amorphous and nanocrystalline materials. The objective of this work is to investigate densification behavior, nanocrystallization, and mechanical properties of SPS sintered Fe-based amorphous alloys of composition Fe48Cr15Mo14Y2C15B6. SPS processing was performed in three distinct temperature ranges of amorphous alloys: (a) below glass transition temperature (Tg), (b) between Tg and crystallization temperature (Tx), and (c) above Tx. Punch displacement data obtained during SPS sintering was correlated with the SPS processing parameters such as temperature, pressure, and sintering time. Powder rearrangement, plastic deformation below T g, and viscous flow of the material between Tg and Tx were observed as the main densification stages during SPS sintering. Micro-scale temperature distributions at the point of contact and macro-scale temperature distribution throughout the sample during SPS of amorphous alloys were modeled. The bulk amorphous alloys are expected to undergo structural relaxation and nanocrystallization during SPS sintering. X-ray diffraction (XRD), small angle neutron scattering (SANS), and transmission electron microscopy (TEM) was performed to investigate the evolution of nanocrystallites in SPS sintered Fe-based bulk amorphous alloys. The SANS analysis showed significant scattering for the samples sintered in the supercooled region indicating local structural and compositional changes with the profuse nucleation of nano-clusters (~4 nm). Compression tests and microhardness were performed on the samples sintered at different

  7. Bond strength of a calcium silicate-based sealer tested in bulk or with different main core materials.

    Science.gov (United States)

    Nagas, Emre; Cehreli, Zafer; Uyanik, Mehmet Ozgur; Durmaz, Veli

    2014-01-01

    The aim of this study was to evaluate the influence of a calcium silicate-based sealer (iRoot SP), with or without a core material, on bond strength to radicular dentin, in comparison with various contemporary root filling systems. Root canals of freshly extracted single-rooted teeth (n = 60) were instrumented using rotary instruments. The roots were randomly assigned to one of the following experimental groups: (1) a calcium silicate-based sealer without a core material (bulk-fill); (2) a calcium silicate-based sealer + gutta-percha; (3) a calcium silicate-based sealer + Resilon; (4) a methacrylate resin-based sealer (RealSeal SE) + Resilon; (5) an epoxy resin-based sealer (AH Plus) + gutta-percha, and (6) a mineral trioxide aggregate-based endodontic sealer (MTA Fillapex) + gutta-percha. Four 1-mm-thick sections were obtained from the coronal aspect of each root (n = 40 slices/group). Push-out bond strength testing was performed at a cross-head speed of 1 mm/min, and the bond strength data were analyzed statistically by one-way analysis of variance and Tukey tests (p core filling materials. When the calcium silicate-based sealer was placed in bulk, its dislocation resistance was similar to that of commonly used sealer + core root filling systems. Thus, the concept of using a calcium silicate-based sealer in bulk can be more easily advocated in clinical practice.

  8. Structure and phase transformations in copper-alloyed rapidly melt-quenched Ni50Ti32Hf18-based alloys with high-temperature shape memory effect

    Science.gov (United States)

    Pushin, A. V.; Pushin, V. G.; Kuranova, N. N.; Kourov, N. I.; Kuntsevich, T. E.; Makarov, V. V.; Uksusnikov, A. N.

    2017-10-01

    Methods of transmission and scanning electron microscopy, chemical microanalysis, electron diffraction, and X-ray diffraction have been used to carry out the comparative study of the structure and chemical and phase composition of thin ribbons of four quasi-binary alloys (Ni50Ti32Hf18, Ni45Ti32Hf18Cu5, Ni35Ti32Hf18Cu15, and Ni25Ti32Hf18Cu25) obtained in the amorphous state by rapid quenching from the melt by jet spinning. The critical temperatures of the devitrification and B2 ↔ B19' martensitic transformation of the alloys have been determined based on the data of temperature dependences of the electrical resistivity. The specific features of the formation of the ultrafine-grained structure upon the devitrification and of the phase transformations have been studied depending on the heat-treatment regimes and chemical composition of the alloys (concentration of copper atoms).

  9. Static and dynamic crack toughness of brazed joints of Inconel 718 nickel-base alloy

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, B.Z. (Technion-Israel Inst. of Tech., Haifa); Steffens, H.D.; Englehart, A.H.; Wielage, B.

    1979-10-01

    The crack toughness of brazed joints of Inconel 718 nickel-base alloy was investigated at different strain rates. The brazing filler metal used was BNi5. The results were compared with those obtained on specimens made of the base material. The brazed joints were heat-treated after the brazing process in order to achieve a desirable distribution of the brittle phases in the joint.

  10. A New Shape Memory Alloy Based Smart Encoder for Sensing of Direction and Angular Motion

    OpenAIRE

    Bishakh BHATTACHARYA; Om Prakash PATEL

    2011-01-01

    This paper presents a novel technique for sensing direction, angle and velocity from rotation of shafts using simple Shape Memory Alloy (SMA) based micro-switches. Due to electro-mechanical coupling of SMA wires reflected in controlled force generation capacity, the SMA based devices can provide better alternatives for traditional relays, solenoid valves and opto-coupler isolators. The control algorithm involved in this sensing technique, reads the switch status for shaft rotation and sense t...

  11. Effects of intensive forced melt convection on the mechanical properties of Fe containing Al-Si based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Fang, X. [BCAST Brunel Centre for Advanced Solidification Technology, Brunel University, Uxbridge, Middlesex UB8 3PH (United Kingdom)]. E-mail: mtsrxxf@brunel.ac.uk; Shao, G. [BCAST Brunel Centre for Advanced Solidification Technology, Brunel University, Uxbridge, Middlesex UB8 3PH (United Kingdom); Liu, Y.Q. [BCAST Brunel Centre for Advanced Solidification Technology, Brunel University, Uxbridge, Middlesex UB8 3PH (United Kingdom); Fan, Z. [BCAST Brunel Centre for Advanced Solidification Technology, Brunel University, Uxbridge, Middlesex UB8 3PH (United Kingdom)

    2007-02-15

    The pickup of impurity Fe is an inherent engineering problem for the recycling of aluminium alloys, due to the detrimental effects of Fe containing intermetallic compounds on the mechanical properties. This work aims to understand the effects of intensive forced melt convection and alloying on the mechanical properties of Fe containing Al-Si based cast alloys. Varied Fe levels were introduced into widely used commercial Al-Si based cast alloys with different Mn contents. The role of intensive forced melt convection was investigated through comparative study of the microstructure properties relationship of alloys that are processed via rheo-diecasting (RDC) and conventional high-pressure diecasting (HPDC), with the former involving intensively shearing the melt in a slurry maker before diecasting. CALPHAD modelling of the thermodynamic properties of the multi-component alloys was carried out to clarify the role of alloying elements on the formation of different primary Fe containing intermetallic compounds. The experimental results show that intensive forced melt convection during solidification promotes the formation of {alpha}-AlFeMnSi compound with a compact morphology. It was also found that Mn as an alloying element assists the conversion of needle-shaped {beta}-AlFeSi compound into more compact {alpha}-AlFeMnSi compound.

  12. Comparison of Crevice Corrosion of Fe-Based Amorphous Metal and Crystalline Ni-Cr-Mo Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Shan, X; Ha, H; Payer, J H

    2008-07-24

    The crevice corrosion behaviors of an Fe-based bulk metallic glass alloy (SAM1651) and a Ni-Cr-Mo crystalline alloy (C-22) were studied in 4M NaCl at 100 C with cyclic potentiodynamic polarization and constant potential tests. The corrosion damage morphologies, corrosion products and the compositions of corroded surfaces of these two alloys were studied with optical 3D reconstruction, Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and Auger Electron Spectroscopy (AES). It was found that the Fe-based bulk metallic glass (amorphous alloy) SAM1651 had a more positive breakdown potential and repassivation potential than crystalline alloy C-22 in cyclic potentiodynamic polarization tests and required a more positive oxidizing potential to initiate crevice corrosion in constant potential test. Once crevice corrosion initiated, the corrosion propagation of C-22 was more localized near the crevice border compared to SAM1651, and SAM1651 repassivated more readily than C-22. The EDS results indicated that the corrosion products of both alloys contained high amount of O and were enriched in Mo and Cr. The AES results indicated that a Cr-rich oxide passive film was formed on the surfaces of both alloys, and both alloys were corroded congruently.

  13. Thermodynamic Considerations of Contamination by Alloying Elements of Remelted End-of-Life Nickel- and Cobalt-Based Superalloys

    Science.gov (United States)

    Lu, Xin; Matsubae, Kazuyo; Nakajima, Kenichi; Nakamura, Shinichiro; Nagasaka, Tetsuya

    2016-06-01

    Cobalt and nickel are high-value commodity metals and are mostly used in the form of highly alloyed materials. The alloying elements used may cause contamination problems during recycling. To ensure maximum resource efficiency, an understanding of the removability of these alloying elements and the controllability of some of the primary alloying elements is essential with respect to the recycling of end-of-life (EoL) nickel- and cobalt-based superalloys by remelting. In this study, the distribution behaviors of approximately 30 elements that are usually present in EoL nickel- and cobalt-based superalloys in the solvent metal (nickel, cobalt, or nickel-cobalt alloy), oxide slag, and gas phases during the remelting were quantitatively evaluated using a thermodynamic approach. The results showed that most of the alloying elements can be removed either in the slag phase or into the gas phase. However, the removal of copper, tin, arsenic, and antimony by remelting is difficult, and they remain as tramp elements during the recycling. On the other hand, the distribution tendencies of iron, molybdenum, and tungsten can be controlled by changing the remelting conditions. To increase the resource efficiency of recycling, preventing contamination by the tramp elements and identifying the alloying compositions of EoL superalloys are significantly essential, which will require the development of efficient prior alloy-sorting systems and advanced separation technologies.

  14. Development of silicide coating over molybdenum based refractory alloy and its characterization

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, S.P., E-mail: spc@barc.gov.i [Materials Processing Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India); Banerjee, S.; Sharma, I.G.; Suri, A.K. [Materials Processing Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India)

    2010-08-15

    Molybdenum based refractory alloys are potential candidate materials for structural applications in high temperature compact nuclear reactors and fusion reactors. However, these alloys being highly susceptible to oxidation in air or oxygen at elevated temperature, undergoes severe losses from highly volatile molybdenum trioxide species. Present investigation, therefore, examines the feasibility of development of silicide type of coating over molybdenum base TZM alloy shape (Mo > 99 wt.%) using pack cementation coating technique. TZM alloy was synthesized in this laboratory from oxide intermediates of MoO{sub 2}, TiO{sub 2} and ZrO{sub 2} in presence of requisite amount of carbon, by alumino-thermic reduction smelting technique. The arc melted and homogenized samples of TZM alloy substrate was then embedded in the chosen and intimately mixed pack composition consisting of inert matrix (Al{sub 2}O{sub 3}), coating powder (Si) and activator (NH{sub 4}Cl) taken in the judicious proportion. The sealed charge packs contained in an alumina crucible were heated at temperatures of 1000 {sup o}C for 8-16 h heating cycle to develop the coating. The coating phase was confirmed to be of made of MoSi{sub 2} by XRD analysis. The morphology of the coating was studied by SEM characterization. It had revealed that the coating was diffusion bonded where Si from coating diffused inward and Mo from TZM substrate diffused outward to form the coating. The coating was found to be resistant to oxidation when tested in air up to 1200 {sup o}C. A maximum 100 {mu}m of coating thickness was achieved on each side of the substrate.

  15. Microstructural characterization of a new mechanically alloyed Ni-base ODS superalloy powder

    Energy Technology Data Exchange (ETDEWEB)

    Seyyed Aghamiri, S.M. [Department of Materials Engineering, Tarbiat Modares University, Tehran 14115-143 (Iran, Islamic Republic of); Shahverdi, H.R., E-mail: Shahverdi@modares.ac.ir [Department of Materials Engineering, Tarbiat Modares University, Tehran 14115-143 (Iran, Islamic Republic of); Ukai, S.; Oono, N.; Taya, K.; Miura, S.; Hayashi, S. [Material Science and Engineering, Faculty of Engineering, Hokkaido University, Sapporo 060-8626 (Japan); Okuda, T. [Kobelco Research Institute Ltd., Kobe 651-2271 (Japan)

    2015-02-15

    The microstructure of a new Ni-base oxide dispersion strengthened superalloy powder was studied for high temperature gas turbine applications after the mechanical alloying process. In this study, an atomized powder with a composition similar to the CMSX-10 superalloy was mechanically alloyed with yttria and Hf powders. The mechanically alloyed powder included only the supersaturated solid solution γ phase without γ′ and yttria provided by severe plastic deformation, while after the 3-step aging, the γ′ phase was precipitated due to the partitioning of Al and Ta to the γ′ and Co, Cr, Re, W, and Mo to the γ phase. Mechanical alloying modified the morphology of γ′ to the new coherent γ–γ′ nanoscale lamellar structure to minimize the elastic strain energy of the precipitation, which yielded a low lattice misfit of 0.16% at high temperature. The γ′ lamellae aligned preferentially along the elastically soft [100] direction. Also, the precipitated oxide particles were refined in the γ phase by adding Hf from large incoherent YAlO{sub 3} to fine semi-coherent Y{sub 2}Hf{sub 2}O{sub 7} oxide particles with the average size of 7 nm and low interparticle spacing of 76 nm. - Highlights: • A new Ni-base ODS superalloy powder was produced by mechanical alloying. • The nanoscale γ–γ′ lamellar structure was precipitated after the aging treatment. • Fine semi-coherent Y{sub 2}Hf{sub 2}O{sub 7} oxide particles were precipitated by addition of Hf.

  16. Biocorrosion behavior and cell viability of adhesive polymer coated magnesium based alloys for medical implants

    Energy Technology Data Exchange (ETDEWEB)

    Abdal-hay, Abdalla [Departmentt of Bionano System Engineering, College of Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Department of Mechanical Design Engineering, Advanced wind power system research institute, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Dewidar, Montasser [Department of Materials and Mechanical Design, Faculty of Energy Engineering, South Valley University, Aswan (Egypt); Lim, Jae Kyoo, E-mail: jklim@jbnu.ac.kr [Department of Mechanical Design Engineering, Advanced wind power system research institute, Chonbuk National University, Jeonju 561-756 (Korea, Republic of)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer The corrosion behavior of magnesium for orthopedic applications is extremely poor. Black-Right-Pointing-Pointer The solvent (DCM, THF and DMF) had a strong effect on the coatings performance. Black-Right-Pointing-Pointer Mg bar alloy coated with PVAc/DCM layers provided an excellent bonding strength. Black-Right-Pointing-Pointer Treated samples indicated significant damping for the degradation rate. Black-Right-Pointing-Pointer Cytocompatibility on MC3T3 cells of the PVAc/DCM samples revealed a good behavior. - Abstract: The present study was ultimately aimed to design novel adhesive biodegradable polymer, poly(vinyl acetate) (PVAc), coatings onto Mg based alloys by the dip-coating technique in order to control the degradation rate and enhance the biocompatibility of magnesium alloys. The influence of various solvents on PVAc surface topography and their protection of Mg alloys were dramatically studied in vitro. Electrochemical polarization, degradation, and PVAc film cytocompatibility were also tested. Our results showed that the solvent had a significant effect on coating quality. PVAc/dichloromethane solution showed a porous structure and solution concentration could control the porous size. The coatings prepared using tetrahydrofuran and dimethylformamide solvents are exceptional in their ability to generate porous morphology even at low polymer concentration. In general, the corrosion performance appears to be different on different PVAc-solvent system. Immersion tests illustrated that the porous morphology on PVAc stabilized corrosion rates. A uniform corrosion attack in artificial simulation body fluid was also exhibited. The cytocompatibility of osteoblast cells (MC3T3) revealed high adherence, proliferation, and survival on the porous structure of PVAc coated Mg alloy, which was not observed for the uncoated samples. This novel PVAc coating is a promising candidate for biodegradable implant materials, which might

  17. Sn-Sb-Se based binary and ternary alloys for phase change memory applications

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Kyung-Min

    2008-10-28

    In this work, the effect of replacing Ge by Sn and Te by Se was studied for a systematic understanding and prediction of new potential candidates for phase change random access memories applications. The temperature dependence of the electrical/structural properties and crystallization kinetics of the Sn-Se based binary and Sn-Sb-Se based ternary alloys were determined and compared with those of the GeTe and Ge-Sb-Te system. The temperature dependence of electrical and structural properties were investigated by van der Pauw measurements, X-ray diffraction, X-ray reflectometry. By varying the heating rate, the Kissinger analysis has been used to determine the combined activation barrier for crystallization. To screen the kinetics of crystallization, a static laser tester was employed. In case of binary alloys of the type Sn{sub x}Se{sub 1-x}, the most interesting candidate is SnSe{sub 2} since it crystallizes into a single crystalline phase and has high electrical contrast and reasonably high activation energy for crystallization. In addition, the SnSe{sub 2}-Sb{sub 2}Se{sub 3} pseudobinary alloy system also might be sufficient for data retention due to their higher transition temperature and activation energy for crystallization in comparison to GeTe-Sb{sub 2}Te{sub 3} system. Furthermore, SnSe{sub 2}-Sb{sub 2}Se{sub 3} pseudobinary alloys have a higher crystalline resistivity. The desired rapid crystallization speed can be obtained for Sn{sub 1}Sb{sub 2}Se{sub 5} and Sn{sub 2}Sb{sub 2}Se{sub 7} alloys. (orig.)

  18. The use of new PHACOMP in understanding the solidification microstructure of nickel base alloy weld metal

    Science.gov (United States)

    Cieslak, M. J.; Knorovsky, G. A.; Headley, T. J.; Romig, A. D.

    1986-12-01

    The weld metal microstructures of five commercial nickel base alloys (HASTELLOYS* C-4, C-22, and C-276, and INCONELS* 625 and 718) have been examined by electron probe microanalysis and analytical electron microscopy. It has been found that solidification terminates in many of these alloys with the formation of a constituent containing a topologically-close-packed (TCP) intermetallic phase (i.e., σ, P, Laves). Electron microprobe examination of gas-tungsten-arc welds revealed a solidification segregation pattern of Ni depletion and solute enrichment in interdendritic volumes. New PHACOMP calculations performed on these segregation profiles revealed a pattern of increasing M d (metal- d levels) in traversing from a dendrite core to an adjacent interdendritic volume. In alloys forming a terminal solidification TCP constituent, the calculated M d values in interdendritic regions were greater than the critical M d values for formation of σ as stated by Morinaga et al. Implications of the correlation between TCP phase formation and M d in the prediction of weld metal solidification microstructure, prediction of potential hot-cracking behavior, and applications in future alloy design endeavors are discussed.

  19. First principles calculation of elastic and magnetic properties of Cr-based full-Heusler alloys

    Science.gov (United States)

    Aly, Samy H.; Shabara, Reham M.

    2014-06-01

    We present an ab-initio study of the elastic and magnetic properties of Cr-based full-Heusler alloys within the first-principles density functional theory. The lattice constant, magnetic moment, bulk modulus and density of states are calculated using the full-potential nonorthogonal local-orbital minimum basis (FPLO) code in the Generalized Gradient Approximation (GGA) scheme. Only the two alloys Co2CrSi and Fe2CrSi are half-metallic with energy gaps of 0.88 and 0.55 eV in the spin-down channel respectively. We have predicted the metallicity state for Fe2CrSb, Ni2CrIn, Cu2CrIn, and Cu2CrSi alloys. Fe2CrSb shows a strong pressure dependent, e.g. exhibits metallicity at zero pressure and turns into a half-metal at P≥10 GPa. The total and partial magnetic moments of these alloys were studied under higher pressure, e.g. in Co2CrIn, the total magnetic moment is almost unchanged under higher pressure up to 500 GPa.

  20. Microstructure of rapidly solidified Nb-based pre-alloyed powders for additive manufacturing

    Science.gov (United States)

    Guo, Yueling; Jia, Lina; Kong, Bin; Zhang, Shengnan; Zhang, Fengxiang; Zhang, Hu

    2017-07-01

    For powder-based additive manufacturing, sphere-shaped Nb-37Ti-13Cr-2Al-1Si pre-alloyed powders were prepared by plasma rotating electrode processing (PREP). The microstructure, surface oxidation and microhardness of the pre-alloyed powders were systematically investigated. Results showed that the main phases were Nb solid solution (Nbss) and Cr2Nb. The Cr2Nb phases were further determined using transmission electron microscopy (TEM). Fine dendrite structures were observed in the as-fabricated pre-alloyed powders, which transformed to large grains after heat treatment (HT) at 1450 °C for 3 h. With the increase of powder size, the secondary dendrite arm spacing (SDAS) increased and the microhardness (HV) decreased. A clean powder surface free of oxide particles was obtained by PREP and an oxide layer with 9.39 nm in thickness was generated on the powder surface. Compared with Cr- and Nb-oxides, more Ti-oxides were formed on outmost powder surface with a higher content of Ti (up to 47.86 at.%). The differences upon the microstructure and microhardness of the pre-alloyed powders with different sizes were discussed.

  1. Stress corrosion cracking mechanisms of Fe-based alloys in hydrogenated hot water

    Energy Technology Data Exchange (ETDEWEB)

    Coull, Z. [Univ. of Toronto, Dept. of Chemical Engineering and Applied Chemistry, Toronto, Ontario (Canada)]. E-mail: zcoull@chem-eng.utoronto.ca

    2006-07-01

    It is generally accepted that carbon steel resists Stress Corrosion Cracking (SCC) in hot water provided the oxygen content is low enough; however, isolated cracking events have occurred, apparently in fully reducing conditions, and these may or may not be true SCC. There are also occasional reports of SCC of austenitic stainless steel in reducing conditions where cold work may play a critical role. SCC though originally seen in sensitized material at oxidizing potentials persists to low potentials and in cold-worked but unsensitized material. We suspect from the literature that alloying with Ni introduces a susceptibility to SCC in reducing hot water as well as in caustic solution. Our hypothesis is that Ni causes SCC, and Cr retards it; so stainless steel has just enough Cr to protect against SCC under most conditions. We are examining this using model Fe-based materials and environments designed to separate the effects of different parameters. Early results suggest that Fe-Ni alloys and austenitic SS both undergo de-alloying and SCC in reducing caustic solutions. It is hypothesised that if these alloys are indeed susceptible to dealloying (and hence to SCC) in this environment then we can reasonably project that their behaviour in reducing, hot pure water may be similar. This is pertinent to understanding recent failures in high temperature, high pressure aqueous systems. As a first step we have investigated the surface reactions that occur in caustic solutions and in hot water. (author)

  2. Self-passivating bulk tungsten-based alloys manufactured by powder metallurgy

    Science.gov (United States)

    López-Ruiz, P.; Ordás, N.; Lindig, S.; Koch, F.; Iturriza, I.; García-Rosales, C.

    2011-12-01

    Self-passivating tungsten-based alloys are expected to provide a major safety advantage compared to pure tungsten, which is at present the main candidate material for the first wall armour of future fusion reactors. WC10Si10 alloys were manufactured by mechanical alloying (MA) in a Planetary mill and subsequent hot isostatic pressing (HIP), achieving densities above 95%. Different MA conditions were studied. After MA under optimized conditions, a core with heterogeneous microstructure was found in larger powder particles, resulting in the presence of some large W grains after HIP. Nevertheless, the obtained microstructure is significantly refined compared to previous work. First MA trials were also performed on the Si-free system WCr12Ti2.5. In this case a very homogeneous structure inside the powder particles was obtained, and a majority ternary metastable bcc phase was found, indicating that almost complete alloying occurred. Therefore, a very fine and homogeneous microstructure can be expected after HIP in future work.

  3. Tribological properties of Al 7075 alloy based composites strengthened with Al2O3 fibres

    Directory of Open Access Journals (Sweden)

    K. Naplocha

    2011-04-01

    Full Text Available Wear resistance of 7075 aluminium alloy based composite materials reinforced with Al2O3 Saffil fibres was investigated. The measurementsof wear were performed applying the pin-on-disc method at dry friction conditions with the gray iron counterpart. The effects ofpressure of composite samples on the counterpart made of gray iron and the orientation of fibers in relation to the friction surface on wear rate were determined. The materials were produced by squeeze casting method where 80-90% porous ceramic preform were infiltrated.After T6 heat treatment hardness increased about 50-60% both for unreinforced alloy and composites containing strengthening Saffilfibres. Wear resistance of composite materials in relation to the unreinforced 7075 alloy was slightly worse at lower pressure of 0.8 MPa. Under higher pressure of 1.2 MPa wear resistance of unreinforced 7075 alloy was even better whereas no effect of orientation of fibers on wear in composite materials was observed. Additionally, significant wear of counterface in the presence of debris with fragmented Al2O3 fibres as abrasives was observed. Wear resistance improvement of composite materials was obtained when with alumina Saffil fibres Carbon C fibres in the preforms were applied.

  4. Effect of Co - based Alloy on Properties of Laser Cladding Layer

    Science.gov (United States)

    Yang, Y.; Jiang, Z. P.; Li, H. Z.

    2017-11-01

    A large number of laser cladding experiments have been carried out using 20CrMnTi steel as substrate and Co-based alloy as cladding material. The influence of Co-based alloy on the laser cladding properties of 20CrMnTi steel was studied by analyzing the macroscopic and microscopic characteristics of cladding crack susceptibility, dilution rate, microstructure and friction and wear properties. The results show that the high-power laser cladding of Co-based material can obtain a flat defect-free cladding layer with compact structure and low crack susceptibility. A multi-layer cladding strategy with variable power can be used to fabricate thin wall structures without collapse Parts, the surface smooth without pores.

  5. Potential effects of ocean acidification on Alaskan corals based on calcium carbonate mineralogy composition analysis (NCEI Accession 0157223)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains potential effects of ocean acidification on Alaskan corals based on calcium carbonate mineralogy composition analysis. Effects of...

  6. Selection of crucible oxides in molten titanium and titanium aluminum alloys by thermo-chemistry calculations

    Directory of Open Access Journals (Sweden)

    Kostov A.

    2005-01-01

    Full Text Available Titanium and its alloys interstitially dissolve a large amount of impurities such as oxygen and nitrogen, which degrade the mechanical and physical properties of alloys. On the other hand crucible oxides based on CaO, ZrO2 Y2O3, etc., and their spinels (combination of two or more oxides can be used for melting titanium and its alloys. However, the thermodynamic behavior of calcium, zirconium, yttrium on the one side, and oxygen on the other side, in molten Ti and Ti-Al alloys have not been made clear and because of that, it is very interesting for research. Owing of literature data, as well as these crucibles are cheaper than standard crucibles for melting titanium and titanium alloys, in this paper will be presented the results of selection of thermo-chemistry analysis with the aim to determine the crucible oxide stability in contact with molten titanium and titanium-aluminum alloys.

  7. Influence of creep damage on the low cycle thermal-mechanical fatigue behavior of two tantalum base alloys

    Science.gov (United States)

    Sheffler, K. D.; Doble, G. S.

    1972-01-01

    Low cycle fatigue tests have been performed on the tantalum base alloys T-111 and ASTAR 811C with synchronized, independently programmed temperature and strain cycling. The thermal-mechanical cycles applied fell into three basic categories: these were isothermal cycling, in-phase thermal cycling, and out-of-phase thermal cycling. In-phase cycling was defined as tensile deformation associated with high temperature and compressive deformation with low temperature, while out-of-phase thermal cycling was defined as the reverse case. The in-phase thermal cycling had a pronounced detrimental influence on the fatigue life of both alloys, with the life reduction being greater in the solid solution strengthened T-111 alloy than in the carbide strengthened ASTAR 811C alloy. The out-of-phase tests also showed pronounced effects on the fatigue life of both alloys, although not as dramatic.

  8. A new titanium based alloy Ti-27Nb-13Zr produced by powder metallurgy with biomimetic coating for use as a biomaterial.

    Science.gov (United States)

    Mendes, Marcio W D; Ágreda, Carola G; Bressiani, Ana H A; Bressiani, José C

    2016-06-01

    Titanium alloys are widely used in biomedical applications due to their excellent properties such as high strength, good corrosion resistance and biocompatibility. Titanium alloys with alloying elements such as Nb and Zr are biocompatible and have Young's modulus close to that of human bone. To increase the bioactivity of titanium alloy surfaces is used chemical treatment with NaOH followed by immersion in simulated body fluid (SBF). The purpose of this study was to produce the alloy Ti-27Nb-13Zr with low Young's modulus by powder metallurgy using powders produced by the HDH process. The formation of biomimetic coatings on samples immersed in SBF for 3, 7, 11 and 15 days was evaluated. Characterization of the coating was performed by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and scanning electron microscope. The microstructure and composition of the alloy were determined using SEM and XRD, while the mechanical properties were evaluated by determining the elastic modulus and the Vickers microhardness. The sintered alloys were composed of α and β phases, equiaxed grains and with density around 97.8% of its theoretical density. The Vickers microhardness and elasticity modulus of the alloy were determined and their values indicate that this alloy can be used as a biomaterial. Analysis of the coating revealed the presence of calcium phosphate layers on samples immersed for >3 days in the SBF solution. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Brushing-induced surface roughness of two nickel based alloys and a titanium based alloy: a comparative study - in vitro study.

    Science.gov (United States)

    Acharya, B L Guruprasanna; Nadiger, Ramesh; Shetty, Bharathraj; Gururaj, G; Kumar, K Naveen; Darshan, D D

    2014-06-01

    toothpastes with the medium abrasives in patients with these restorations. How to cite the article: Acharya BL, Nadiger R, Shetty B, Gururaj G, Kumar KN, Darshan DD. Brushing induced surface roughness of two nickel based alloys and a titanium based alloy: A comparative study - In vitro study. J Int Oral Health 2014;6(3):36-49.

  10. First principles calculation of elastic and magnetic properties of Cr-based full-Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Aly, Samy H., E-mail: samy.ha.aly@gmail.com; Shabara, Reham M., E-mail: rehamph@hotmail.com

    2014-06-01

    We present an ab-initio study of the elastic and magnetic properties of Cr-based full-Heusler alloys within the first-principles density functional theory. The lattice constant, magnetic moment, bulk modulus and density of states are calculated using the full-potential nonorthogonal local-orbital minimum basis (FPLO) code in the Generalized Gradient Approximation (GGA) scheme. Only the two alloys Co{sub 2}CrSi and Fe{sub 2}CrSi are half-metallic with energy gaps of 0.88 and 0.55 eV in the spin-down channel respectively. We have predicted the metallicity state for Fe{sub 2}CrSb, Ni{sub 2}CrIn, Cu{sub 2}CrIn, and Cu{sub 2}CrSi alloys. Fe{sub 2}CrSb shows a strong pressure dependent, e.g. exhibits metallicity at zero pressure and turns into a half-metal at P≥10 GPa. The total and partial magnetic moments of these alloys were studied under higher pressure, e.g. in Co{sub 2}CrIn, the total magnetic moment is almost unchanged under higher pressure up to 500 GPa. - Highlights: • This study is a novel study on properties of Ni{sub 2}CrIn, Cu{sub 2}CrIn, Cu{sub 2}CrSi and Fe{sub 2}CrSb. • We have calculated the lattice constant, bulk modulus, energy gap, and DOS. • Half-metallic property is found only in both Co{sub 2}CrSi and Fe{sub 2}CrSi alloys. • Total and partial magnetic moments were studied under high pressure.

  11. Physicochemical Properties of Calcium Phosphate Based Coating on Gutta-Percha Root Canal Filling

    Directory of Open Access Journals (Sweden)

    Afaf Al-Haddad

    2015-01-01

    Full Text Available Dental Gutta-percha (GP is a polymer based standard root canal filling material that has been widely used in dentistry. However, it has an inadequate sealing ability and adhesion to root dentin. The aim of this study is to coat GP with a bioactive material to enhance its sealing ability and adhesion to the root sealer and subsequently to the root dentin. The choice of coating method is limited by the nature of GP as it requires a technique that is not governed by high temperatures or uses organic solvents. In this study, biomimetic coating technique using 1.5 Tas-simulated body fluids (SBF was employed to coat the treated GP cones. The coated samples were characterized using Fourier transform infrared spectroscopy (FTIR, X-ray Diffraction (XRD, and field emission scanning electron microscope (FESEM. The presence of hydroxyl, carbonate, and phosphate groups was detected by FTIR while the formation of hydroxyapatite (HA/calcium phosphate was confirmed with XRD. FESEM revealed uniform, thin, and crystalline HA calcium phosphate coating. The adhesion of the coating to the GP substrate was assessed with microscratch technique. It was viable with cohesive failure mode. In conclusion, Tas-SBF is able to coat pretreated GP cones with a crystalline apatitic calcium phosphate layer.

  12. Designing calcium phosphate-based bifunctional nanocapsules with bone-targeting properties

    Energy Technology Data Exchange (ETDEWEB)

    Khung, Yit-Lung; Bastari, Kelsen; Cho, Xing Ling; Yee, Wu Aik; Loo, Say Chye Joachim, E-mail: joachimloo@ntu.edu.sg [Nanyang Technological University, School of Materials Science and Engineering (Singapore)

    2012-06-15

    Using sodium dodecyl sulphate micelles as template, hollow-cored calcium phosphate nanocapsules were produced. The surfaces of the nanocapsule were subsequently silanised by a polyethylene glycol (PEG)-based silane with an N-hydroxysuccinimide ester end groups which permits for further attachment with bisphosphonates (BP). Characterisations of these nanocapsules were investigated using Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy, Fourier Transform Infra-Red Spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Dynamic Light Scattering. To further validate the bone-targeting potential, dentine discs were incubated with these functionalised nanocapsules. FESEM analysis showed that these surface-modified nanocapsules would bind strongly to dentine surfaces compared to non-functionalised nanocapsules. We envisage that respective components would give this construct a bifunctional attribute, whereby (1) the shell of the calcium phosphate nanocapsule would serve as biocompatible coating aiding in gradual osteoconduction, while (2) surface BP moieties, acting as targeting ligands, would provide the bone-targeting potential of these calcium phosphate nanocapsules.

  13. Mechanical Properties of Aluminum-Based Dissimilar Alloy Joints by Power Beams, Arc and FSW Processes

    Science.gov (United States)

    Okubo, Michinori; Kon, Tomokuni; Abe, Nobuyuki

    Dissimilar smart joints are useful. In this research, welded quality of dissimilar aluminum alloys of 3 mm thickness by various welding processes and process parameters have been investigated by hardness and tensile tests, and observation of imperfection and microstructure. Base metals used in this study are A1050-H24, A2017-T3, A5083-O, A6061-T6 and A7075-T651. Welding processes used are YAG laser beam, electron beam, metal inert gas arc, tungsten inert gas arc and friction stir welding. The properties of weld zones are affected by welding processes, welding parameters and combination of base metals. Properties of high strength aluminum alloy joints are improved by friction stir welding.

  14. AB INITIO Modeling of Thermomechanical Properties of Mo-Based Alloys for Fossil Energy Conversion

    Energy Technology Data Exchange (ETDEWEB)

    Ching, Wai-Yim

    2013-12-31

    In this final scientific/technical report covering the period of 3.5 years started on July 1, 2011, we report the accomplishments on the study of thermo-mechanical properties of Mo-based intermetallic compounds under NETL support. These include computational method development, physical properties investigation of Mo-based compounds and alloys. The main focus is on the mechanical and thermo mechanical properties at high temperature since these are the most crucial properties for their potential applications. In particular, recent development of applying ab initio molecular dynamic (AIMD) simulations to the T1 (Mo{sub 5}Si{sub 3}) and T2 (Mo{sub 5}SiB{sub 2}) phases are highlighted for alloy design in further improving their properties.

  15. Hardness analysis and morphological characterization of copper-zinc alloys produced in pyrophosphate-based electrolytes

    Directory of Open Access Journals (Sweden)

    Lilian Ferreira de Senna

    2005-09-01

    Full Text Available In this work, copper-zinc alloy coatings on mild steel substrates were obtained in nontoxic pyrophosphate-based electrolytes, at room temperature and under continuous current. The effects of bath composition and current density on the hardness of the coatings, as well as on their morphologies, were evaluated. The results showed that the electrolyte composition, and the use of stress relieving additives strongly influence the hardness of the coatings, while the current density directly affect their morphology. Hence, for a current density of 116 A/m², copper-zinc alloy deposits with no pores or cracks were produced in a pyrophosphate-based electrolyte, especially when allyl alcohol was added to the solution.

  16. Effects of Solidification Conditions on the Crystal Selection Behavior of an Al Base Alloy During Directional Solidification

    Science.gov (United States)

    Liu, Jin-lai; Jin, Tao; Luo, Xiong-hong; Feng, Shao-bo; Zhao, Jiu-zhou

    2016-05-01

    Al base alloy can be used as model alloy of Ni base single crystal superalloy due to their similarity on microstructure, while its lower melt temperature can match the restricted temperature of furnace working in space. The crystal selection behavior Al base alloy during directional solidification is studied by Bridgman process. With rise of heating temperature and decrease of withdraw rate, the number of grains passed spiral selector reduces. At heating temperature 900 ∘C and withdraw rate 2mm/min, an Al base single crystal alloy can be produced. At higher heating temperature more Mg segregates to dendrite stem, which cause smaller liquid volume fraction. At lower withdraw rate less Cu segregate to interdendrite region, which cause reduced constitutional undercooling. These two factors lead to the shrinkage of secondary dendrite arm, thus the efficiency of spiral selector is improved.

  17. Microstructures and Mechanical Properties of Co-Cr Dental Alloys Fabricated by Three CAD/CAM-Based Processing Techniques

    National Research Council Canada - National Science Library

    Kim, Hae; Jang, Seong-Ho; Kim, Young; Son, Jun; Min, Bong; Kim, Kyo-Han; Kwon, Tae-Yub

    2016-01-01

    The microstructures and mechanical properties of cobalt-chromium (Co-Cr) alloys produced by three CAD/CAM-based processing techniques were investigated in comparison with those produced by the traditional casting technique...

  18. Solubility and apical sealing characteristics of a new calcium silicate-based root canal sealer in comparison to calcium hydroxide-, methacrylate resin- and epoxy resin-based sealers.

    Science.gov (United States)

    Ersahan, Seyda; Aydin, Cumhur

    2013-01-01

    To assess and compare the water sorption, solubility and apical sealing ability of iRoot SP and three other widely used root canal sealers. Solubility was assessed by immersing standardized samples of calcium silicate- (iRoot SP), calcium hydroxide- (Sealapex), methacrylate resin- (EndoREZ) and epoxy resin- (AH Plus) based sealers in distilled water and measuring weight gain and weight loss at 6 h, 24 h and daily for 14 days. Roots of extracted mandibular premolars (n = 80) were prepared with 0.04-taper nickel-titanium rotary files to a final size 40. Roots were then randomly divided into four experimental groups (n = 18) and two control groups (n = 4), root canal sealers were applied and apical leakage was assessed using the fluid filtration method. Data was analyzed using Kruskal Wallis analysis of variance and Mann-Whitney U-tests, with the level of significance set at p ≤ 0.05. EndoREZ exhibited the highest water sorption, followed by iRoot SP, Sealapex and AH Plus. Sealapex exhibited significantly higher solubility than the other sealers, whereas no significant differences in solubility levels were observed between the other three sealers tested. AH Plus exhibited significantly lower microleakage than Sealapex and EndoREZ, whereas no difference in microleakage was found between AH Plus and iRoot SP. In view of the study findings, all tested sealers except Sealapex met the ANSI/ADA's requirements for solubility and no difference was found between AH Plus and iRoot SP in terms of apical sealing ability.

  19. Effect of Grain Size on Ultrasonic Fatigue Properties of Ni-Base Super Alloy Inconel 718

    OpenAIRE

    皮籠石, 紀雄; 前村, 英史; 陳, 強; 後藤, 真宏; 森野, 数博

    2008-01-01

    Ultrasonic fatigue tests of plain specimens with different grain sizes were carried out for Ni-base super alloy, Inconel 718, in ambient air in order to investigate the effect of grain size on fatigue properties. Fatigue strength was increased with decrease in grain size. The increase in fatigue strength by refining grain size was mainly caused by the suppression of crack initiation. That is, the effect of grain size on crack growth rate was hardly recognized, though crack morphology was roug...

  20. Stress-Stain State of Pipe Made of Copper-Based Alloy Strengthened with Incoherent Nanoparticles

    Science.gov (United States)

    Matvienko, O. V.; Daneyko, O. I.; Kovalevskaya, T. A.

    2017-08-01

    The approach which combines methods of crystal plasticity and deformable solid mechanics is used to explore the stress-strain state of a heavy-wall pipe made of dispersion-hardened Cu-based alloy and subjected to the uniform internal pressure. The distribution of the deformation and stress along the pipe wall is determined for various pipe geometry. The approximating equations are obtained to determine the yielding area and elastic and plastic strength limits.

  1. A new titanium based alloy Ti–27Nb–13Zr produced by powder metallurgy with biomimetic coating for use as a biomaterial

    Energy Technology Data Exchange (ETDEWEB)

    Mendes, Marcio W.D., E-mail: mwdmendes@ipen.com; Ágreda, Carola G.; Bressiani, Ana H.A.; Bressiani, José C.

    2016-06-01

    Titanium alloys are widely used in biomedical applications due to their excellent properties such as high strength, good corrosion resistance and biocompatibility. Titanium alloys with alloying elements such as Nb and Zr are biocompatible and have Young's modulus close to that of human bone. To increase the bioactivity of titanium alloy surfaces is used chemical treatment with NaOH followed by immersion in simulated body fluid (SBF). The purpose of this study was to produce the alloy Ti–27Nb–13Zr with low Young's modulus by powder metallurgy using powders produced by the HDH process. The formation of biomimetic coatings on samples immersed in SBF for 3, 7, 11 and 15 days was evaluated. Characterization of the coating was performed by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and scanning electron microscope. The microstructure and composition of the alloy were determined using SEM and XRD, while the mechanical properties were evaluated by determining the elastic modulus and the Vickers microhardness. The sintered alloys were composed of α and β phases, equiaxed grains and with density around 97.8% of its theoretical density. The Vickers microhardness and elasticity modulus of the alloy were determined and their values indicate that this alloy can be used as a biomaterial. Analysis of the coating revealed the presence of calcium phosphate layers on samples immersed for > 3 days in the SBF solution. - Highlights: • The alloy is classified as α + β and the milling time influences the formation of these phases. • Dissolution of Nb is related to the mechanical properties of the alloy. • It's possible to form apatite on all samples immersed in SBF from 3 days. • The alloy can be used in orthopedic applications or in dental applications.

  2. Spin-transfer magnetization switching in ordered alloy-based nanopillar devices

    Energy Technology Data Exchange (ETDEWEB)

    Mitani, S [National Institute for Materials Science, Tsukuba 305-0047 (Japan)

    2011-09-28

    This paper reviews spin-transfer magnetization switching in ordered alloy-based nanopillar devices. L1{sub 0}-ordered FePt was used for one of the earliest demonstrations of spin-transfer switching in perpendicularly magnetized systems. The behaviour of magnetization switching deviates from the predictions based on a macro-spin model, suggesting incoherent magnetization switching in the system with a large perpendicular magnetic anisotropy. The effect of a 90{sup 0} spin injector on spin-transfer switching was also examined using L1{sub 0}-ordered FePt. Full-Heusler alloys are in another fascinating material class for spin-transfer switching because of their high-spin polarization of conduction electrons and possible small magnetization damping. A B2-ordered Co{sub 2}FeAl{sub 0.5}Si{sub 0.5}-based device showed a low intrinsic critical current density of 9.3 x 10{sup 6} A cm{sup -2} for spin-transfer switching as well as a relatively large current-perpendicular-to-plane giant-magnetoresistance (CPP-GMR) up to {approx}9%. The specific physical properties of ordered alloys may be useful for fundamental studies and applications in spin-transfer switching.

  3. Spin-transfer magnetization switching in ordered alloy-based nanopillar devices

    Science.gov (United States)

    Mitani, S.

    2011-09-01

    This paper reviews spin-transfer magnetization switching in ordered alloy-based nanopillar devices. L10-ordered FePt was used for one of the earliest demonstrations of spin-transfer switching in perpendicularly magnetized systems. The behaviour of magnetization switching deviates from the predictions based on a macro-spin model, suggesting incoherent magnetization switching in the system with a large perpendicular magnetic anisotropy. The effect of a 90° spin injector on spin-transfer switching was also examined using L10-ordered FePt. Full-Heusler alloys are in another fascinating material class for spin-transfer switching because of their high-spin polarization of conduction electrons and possible small magnetization damping. A B2-ordered Co2FeAl0.5Si0.5-based device showed a low intrinsic critical current density of 9.3 × 106 A cm-2 for spin-transfer switching as well as a relatively large current-perpendicular-to-plane giant-magnetoresistance (CPP-GMR) up to ~9%. The specific physical properties of ordered alloys may be useful for fundamental studies and applications in spin-transfer switching.

  4. Calcium - urine

    Science.gov (United States)

    Urinary Ca+2; Kidney stones - calcium in urine; Renal calculi - calcium in your urine; Parathyroid - calcium in urine ... Urine calcium level can help your provider: Decide on the best treatment for the most common type of kidney ...

  5. Ab initio study of effect of Co substitution on the magnetic properties of Ni and Pt-based Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Tufan, E-mail: tufanroyburdwan@gmail.com [Theory and Simulations Lab, HRDS, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai 400094 (India); Chakrabarti, Aparna [Theory and Simulations Lab, HRDS, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai 400094 (India)

    2017-04-25

    Using density functional theory based calculations, we have carried out in-depth studies of effect of Co substitution on the magnetic properties of Ni and Pt-based shape memory alloys. We show the systematic variation of the total magnetic moment, as a function of Co doping. A detailed analysis of evolution of Heisenberg exchange coupling parameters as a function of Co doping has been presented here. The strength of RKKY type of exchange interaction is found to decay with the increase of Co doping. We calculate and show the trend, how the Curie temperature of the systems vary with the Co doping. - Highlights: • We discuss the effects of Co doping on magnetic properties of Ni/Pt based Heusler alloys. • Indirect RKKY interaction is maximum for shape memory alloy like systems. • We predict Pt{sub 2}MnSn as a probable ferromagnetic shape memory alloy.

  6. Hybrid coating on a magnesium alloy for minimizing the localized degradation for load-bearing biodegradable mini-implant applications

    Energy Technology Data Exchange (ETDEWEB)

    Kannan, M. Bobby, E-mail: bobby.mathan@jcu.edu.au; Liyanaarachchi, S.

    2013-10-01

    The effect of a hybrid coating, calcium phosphate (CaP) + polylactic acid (PLA), on a magnesium alloy on its in vitro degradation (general and localized) behaviour was studied for potential load-bearing biodegradable mini-implant applications. CaP was coated on a magnesium alloy, AZ91, using an electrochemical deposition method. A spin coating method was used to coat PLA on the CaP coated alloy. In vitro degradation performance of the alloy with hybrid coating was evaluated using electrochemical impedance spectroscopy (EIS) in simulated body fluid (SBF). The EIS results showed that the hybrid coating enhanced the degradation resistance of the alloy by more than two-order of magnitude as compared to the bare alloy and one-order of magnitude higher than that of the CaP coated alloy, after 1 h exposure in simulated body fluid (SBF). Long-term (48 h) EIS results also confirmed that the hybrid coating performed better than the bare alloy and the CaP coated alloy. Importantly, the hybrid coating improved the localized degradation resistance of the alloy significantly, which is critical for better in service mechanical integrity. - Highlights: • A hybrid coating (CaP + PLA) was applied on a magnesium-based alloy. • The hybrid coating enhanced the in vitro degradation resistance of the alloy. • Localized degradation resistance was also improved by the hybrid coating.

  7. Effect of Multiple Alloying Elements on the Glass-Forming Ability, Thermal Stability, and Crystallization Behavior of Zr-Based Alloys

    Science.gov (United States)

    Bazlov, A. I.; Tsarkov, A. A.; Ketov, S. V.; Suryanarayana, C.; Louzguine-Luzgin, D. V.

    2018-02-01

    Effect of multiple alloying elements on the glass-forming ability, thermal stability, and crystallization behavior of Zr-based glass-forming alloys were studied in the present work. We investigated the effect of complete or partial substitution of Ti and Ni with similar early and late transition metals, respectively, on the glass-forming ability and crystallization behavior of the Zr50Ti10Cu20Ni10Al10 alloy. Poor correlation was observed between different parameters indicating the glass-forming ability and the critical size of the obtained glassy samples. Importance of the width of the crystallization interval is emphasized. The kinetics of primary crystallization, i.e., the rate of nucleation and rate of growth of the nuclei of primary crystals is very different from that of the eutectic alloys. Thus, it is difficult to estimate the glass-forming ability only on the basis of the empirical parameters not taking into account the crystallization behavior and the crystallization interval.

  8. Comparison of joining processes for Haynes 230 nickel based super alloy

    Science.gov (United States)

    Williston, David Hugh

    Haynes 230 is a nickel based, solid-solution strengthened alloy that is used for high-temperature applications in the aero-engine and power generation industries. The alloy composition is balanced to avoid precipitation of undesirable topologically closed-packed (TCP) intermetallic phases, such as Sigma, Mu, or Laves-type, that are detrimental to mechanical and corrosion properties. This material is currently being used for the NASA's J2X upper stage rocket nozzle extension. Current fabrication procedures use fusion welding processes to join blanks that are subsequently formed. Cracks have been noted to occur in the fusion welded region during the forming operations. Use of solid state joining processes, such as friction stir welding are being proposed to eliminate the fusion weld cracks. Of interest is a modified friction stir welding process called thermal stir welding. Three welding process: Gas Metal Arc Welding (GMAW), Electron Beam Welding (EBW), and Thermal Stir Welding (TSWing) are compared in this study.

  9. Remanufacture of Zirconium-Based Conversion Coatings on the Surface of Magnesium Alloy

    Science.gov (United States)

    Liu, Zhe; Jin, Guo; Song, Jiahui; Cui, Xiufang; Cai, Zhaobing

    2017-04-01

    Brush plating provides an effective method for creating a coating on substrates of various shapes. A corroded zirconium-based conversion coating was removed from the surface of a magnesium alloy and then replaced with new coatings prepared via brush plating. The structure and composition of the remanufactured coating were determined via x-ray photoelectron spectroscopy, x-ray diffraction, and Fourier transform infrared spectroscopy. The results revealed that the coatings consist of oxide, fluoride, and tannin-related organics. The composition of the coatings varied with the voltage. Furthermore, as revealed via potentiodynamic polarization spectroscopy, these coatings yielded a significant increase in the corrosion resistance of the magnesium alloy. The friction coefficient remained constant for almost 300s during wear resistance measurements performed under a 1-N load and dry sliding conditions, indicating that the remanufactured coatings provide effective inhibition to corrosion.

  10. Enhanced carbon tolerance on Ni-based reforming catalyst with Ir alloying: A DFT study

    Science.gov (United States)

    Ahn, Kiyong; Choi, Sungjun; Lee, Jong-Ho; Kim, Byung-Kook; Kim, Jedo; Kim, Hyoungchul

    2017-10-01

    Carbon deposition is a major cause of performance degradation for the Ni-based catalyst used in steam reforming of hydrocarbons. In this work, we perform first principle calculations to show that carbon tolerance behavior can be significantly enhanced by alloying Ni with Ir. The most stable atomic structure predicted by the surface phased diagram shows that Ir atoms prefer to stay on the surface of the alloy ensuring their exposure to the incoming gas. We find that the presence of Ir atoms suppress the surface migration of carbon atoms and weaken the stability of the adsorbed carbon agglomerates. Finally, we elucidate that the local reactivity change caused by the shift in the d-band structure is responsible for such good carbon tolerance behavior.

  11. Lithium based alloy-thionyl chloride cells for applications at temperatures to 200 C

    Science.gov (United States)

    Kane, P.; Marincic, N.; Epstein, J.; Lindsey, A.

    A long-life lithium battery for industrial applications at temperatures up to 200 C was developed by combining Li-based alloy anodes with oxyhalide electrolytes. Cathodes were fabricated by rolling the blend of polycarbonomonofluoride, a conductive carbon additive, and a binder, while anodes were fabricated as those used in oxyhalide cells, incorporating a modified anode current collector designed to prevent the formation of 'lithium islands' at the end of discharge; nonwoven glass fiber separators were pretreated to remove excessive binders and lubricants. Various active electrode surface areas were combined with a corresponding thickness of electrodes and separators, matched in capacity. Tests of the high-rate electrode structure, using Li-Mg alloy anode in conjunction with thionyl chloride electrolyte, have demonstrated that the battery with this anode can be used under abusive conditions such as short circuit and external heating (at 175 C). Raising the operating temperature to 200 C did require some modifications of regular cell hardware.

  12. Emeraldine base as corrosion protective layer on aluminium alloy AA5182, effect of the surface microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Cecchetto, L. [Laboratoire d' Electrochimie et de Physicochimie des Materiaux et des Interfaces, CNRS-UJF-INP-Grenoble (UMR 5631), ENSEEG, BP 75, 38402 St. Martin d' Heres (France); Ambat, R. [School of Engineering Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Davenport, A.J. [School of Engineering Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Delabouglise, D. [Laboratoire d' Electrochimie et de Physicochimie des Materiaux et des Interfaces, CNRS-UJF-INP-Grenoble (UMR 5631), ENSEEG, BP 75, 38402 St. Martin d' Heres (France)]. E-mail: Didier.Delabouglise@lepmi.inpg.fr; Petit, J.-P. [Laboratoire d' Electrochimie et de Physicochimie des Materiaux et des Interfaces, CNRS-UJF-INP-Grenoble (UMR 5631), ENSEEG, BP 75, 38402 St. Martin d' Heres (France); Neel, O. [Centre de Recherche de Voreppe, Pechiney, Parc economique Centr' Alp, 38340 Voreppe (France)

    2007-02-15

    AA5182 aluminium alloy cold rolled samples were coated by thin films of emeraldine base (EB) obtained from a 5% solution in N-methylpyrrolidinone. Accelerated corrosion tests prove this coating very effective for corrosion protection of aluminium alloys in neutral environment. This study underlines the prominent role of surface cathodic intermetallic particles in pit initiation and coating break down in enhanced corrosion conditions and suggest that, beside the EB barrier properties, the enhanced corrosion resistance observed on the EB coated samples could partly arise from two other mains factors:- a weak redox activity of the polymer which passivate the metal, - a proton involving self-healing process taking place at the polymer-metal interface, which contributes to delay local acidification in first steps of corrosion on EB coated aluminium surfaces.

  13. Low cycle fatigue properties and an energy-based approach for as-extruded AZ31 magnesium alloy

    Science.gov (United States)

    Kwon, S. H.; Song, K. S.; Shin, K. S.; Kwun, S. I.

    2011-04-01

    Low cycle fatigue tests were conducted to investigate the cyclic deformation behavior and the energy-based criterion of AZ31 magnesium alloy. The alloy exhibited an asymmetric hysteresis loop due to the twinning and detwinning effect. The cyclic stress responses showed cyclic hardening at all total strain amplitudes. To evaluate the plastic strain energy, the Halford-Morrow equation and a modified equation for magnesium alloy were compared. The effect of twinning on the total plastic strain energy dissipated during fatigue life was discussed. The variations of the twin and dislocation densities were also investigated using optical microscopy and transmission electron microscopy, respectively.

  14. GRCop-84: A High Temperature Copper-based Alloy For High Heat Flux Applications

    Science.gov (United States)

    Ellis, David L.

    2005-01-01

    While designed for rocket engine main combustion chamber liners, GRCop-84 (Cu-8 at.% Cr-4 at.% Nb) offers potential for high heat flux applications in industrial applications requiring a temperature capability up to approximately 700 C (1292 F). GRCop-84 is a copper-based alloy with excellent elevated temperature strength, good creep resistance, long LCF lives and enhanced oxidation resistance. It also has a lower thermal expansion than copper and many other low alloy copper-based alloys. GRCop-84 can be manufactured into a variety of shapes such as tubing, bar, plate and sheet using standard production techniques and requires no special production techniques. GRCop-84 forms well, so conventional fabrication methods including stamping and bending can be used. GRCop-84 has demonstrated an ability to be friction stir welded, brazed, inertia welded, diffusion bonded and electron beam welded for joining to itself and other materials. Potential applications include plastic injection molds, resistance welding electrodes and holders, permanent metal casting molds, vacuum plasma spray nozzles and high temperature heat exchanger applications.

  15. The effect of nanobioceramic reinforcement on mechanical and biological properties of Co-base alloy/hydroxyapatite nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Bahrami, M., E-mail: m.bahrami@ma.iut.ac.ir; Fathi, M.H.; Ahmadian, M.

    2015-03-01

    The goal of the present research was to fabricate, characterize, and evaluate mechanical and biological properties of Co-base alloy composites with different amounts of hydroxyapatite (HA) nanopowder reinforcement. The powder of Co–Cr–Mo alloy was mixed with different amounts of HA by ball milling and it was then cold pressed and sintered. X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques were used. Microhardness measurement and compressive tests were also carried out. Bioactivity behavior was evaluated in simulated body fluid (SBF). A significant decrease in modulus elasticity and an increase in microhardness of the sintered composites were observed. Apatite formation on the surface of the composites showed that it could successfully convert bioinert Co–Cr–Mo alloy to bioactive type by adding 10, 15, and 20 wt.% HA which have lower modulus elasticity and higher microhardness. - Graphical abstract: The present investigation has been based on the production of composite materials based on Co–Cr–Mo alloy with different amounts of hydroxyapatite nanobioceramic powder using the powder metallurgy route. Mechanical and biological properties of the composites were investigated. A significant increase in microhardness and decrease in modulus elasticity of the sintered composites were observed. - Highlights: • Co-base alloy/hydroxyapatite composites were prepared by powder metallurgy. • Composite microhardness is improved in comparison with Co-base alloy. • Modulus elasticity decrease by about 53–63% in comparison with Co-base alloy. • Apatite nucleus is formed on the surface of composites after soaking test. • Bioinert Co–Cr–Mo alloy is successfully converted to a bioactive type.

  16. A high stability optical frequency reference based on thermal calcium atoms

    Science.gov (United States)

    2011-05-21

    simple, compact optical frequency standard based upon thennal calcium atoms. Using a Ramsey- Borde specu·ometer we excite features with linewidths < 5kHz...Optical Frequency (kHz) Figure 2: Ramsey- Borde fringes , shown here with both recoil components. Fringe width is < 5kHz (FWHM). tlli.s theoretical value...send ~ 2 m W of the light to a fom-beam Ramsey- Borde spectrometer that excites the atoms in a thermal beam [3]. Atoms emerge from an aperture in theCa

  17. POSITIONS OF CALCIUM CHANNEL BLOCKER LERCANIDIPINE ACCORDING TO EVIDENCE BASED CARDIOLOGY

    Directory of Open Access Journals (Sweden)

    Yu. V. Lukina

    2010-01-01

    Full Text Available Data of evidence based cardiology including results of international clinical trials on efficacy and safety of the modern calcium channel blocker (CCB, lercanidipine, are presented. Results of these trials show the firm position of lercanidipine in the modern cardiology and confirm that treatment with lercanidipine leads to significant reduction of systolic and diastolic blood pressure (BP with no effect on heart rate (HR. Peripheral edema (the common side effect of CCBs occurs rarer with lercanidipine treatment than this with any other CCB treatment. Lercanidipine can be recommended to patients with concomitant diseases due to its additional features.

  18. Effect of Immersion in Simulated Body Fluid on the Mechanical Properties and Biocompatibility of Sintered Fe–Mn-Based Alloys

    Directory of Open Access Journals (Sweden)

    Zhigang Xu

    2016-12-01

    Full Text Available Fe–Mn-based degradable biomaterials (DBMs are promising candidates for temporary implants such as cardiovascular stents and bone fixation devices. Identifying their mechanical properties and biocompatibility is essential to determine the feasibility of Fe–Mn-based alloys as DBMs. This study presents the tensile properties of two powder metallurgical processed Fe–Mn-based alloys (Fe–28Mn and Fe–28Mn-3Si, in mass percent as a function of immersion time in simulated body fluid (SBF. In addition, short-term cytotoxicity testing was performed to evaluate the in vitro biocompatibility of the sintered Fe–Mn-based alloys. The results reveal that an increase in immersion duration deteriorated the tensile properties of both the binary and ternary alloys. The tensile properties of the immersed alloys were severely degraded after being soaked in SBF for ≥45 days. The ion concentration in SBF released from the Fe–28Mn-3Si samples was higher than their Fe–28Mn counterparts after 7 days immersion. The preliminary cytotoxicity testing based on the immersed SBF medium after 7 days immersion suggested that both the Fe–28Mn-3Si and Fe–28Mn alloys presented a good biocompatibility in Murine fibroblast cells.

  19. Internal nitridation of nickel-base alloys; Innere Nitrierung von Nickelbasis-Legierungen

    Energy Technology Data Exchange (ETDEWEB)

    Krupp, U.; Christ, H.J. [Siegen Univ. (Gesamthochschule) (Germany). Inst. fuer Werkstofftechnik

    1998-12-31

    The chromuim concentration is the crucial variable in nitridation processes in nickel-base alloys. Extensive nitridation experiments with various specimen alloys of the system Ni-Cr-Al-Ti have shown that the Cr itself starts to form nitrides as from elevated initial concentrations of about 10 to 20 weight%, (depending on temperature), but that lower concentrations have an earlier effect in that they induce a considerable increase in the N-solubility of the nickel-base alloys. This causes an accelerated nitridation attack on the alloying elements Ti and Al. Apart from experimental detection and analysis, the phenomenon of internal nitridation could be described as well by means of a mathematical model calculating the diffusion with the finite-differences method and determining the precipitation thermodynamics by way of integrated equilibrium calculations. (orig./CB) [Deutsch] Im Verlauf der Hochtemperaturkorrosion von Nickelbasis-Superlegierungen kann durch beanspruchungsbedingte Schaedigungen der Oxiddeckschicht ein Verlust der Schutzwirkung erfolgen und als Konsequenz Stickstoff aus der Atmosphaere in den Werkstoff eindringen. Der eindiffundierende Stickstoff bildet vor allem mit den Legierungselementen Al, Cr und Ti Nitridausscheidungen, die zu einer relativ rasch fortschreitenden Schaedigung fuehren koennen. Eine bedeutende Rolle bei diesen Nitrierungsprozessen in Nickelbasislegierungen spielt die Cr-Konzentration in der Legierung. So ergaben umfangreiche Nitrierungsexperimente an verschiedenen Modellegierungen des Systems Ni-Cr-Al-Ti, dass Cr zwar selbst erst ab Ausgangskonzentrationen von ca. 10-20 Gew.% (abhaengig von der Temperatur) Nitride bildet, allerdings bereits bei geringen Konzentrationen die N-Loeslichkeit von Nickelbasis-Legierungen entscheidend erhoeht. Dies hat zur Folge, dass es zu einem beschleunigten Nitrierungsangriff auf die Legierungselemente Ti und Al kommt. Neben den experimentellen Untersuchungen konnte das Phaenomen der inneren

  20. Altering the level of calcium changes the physical properties and digestibility of casein-based emulsion gels.

    Science.gov (United States)

    McIntyre, Irene; O Sullivan, Michael; O Riordan, Dolores

    2017-04-19

    Casein-based emulsion gels prepared with different types of lipid (i.e. milk fat or rapeseed oil) were formulated with high (774 mg Ca per 100 g) or low (357 mg Ca per 100 g) calcium levels by blending acid and rennet casein. Their physicochemical characteristics (i.e. composition, texture, microstructure & water mobility) and in vitro digestibility were compared to conventionally formulated high-calcium (723 mg Ca per 100 g) emulsion gels made from rennet casein with calcium chelating salts (CCS). CCS-free, high-calcium emulsion gels were significantly (p ≤ 0.05) softer than those with low calcium levels (possibly due to their shorter manufacture time and higher pH) and showed the highest rates of disintegration during simulated gastric digestion. Despite having a higher moisture to protein ratio, the high-calcium emulsion gels containing CCS had broadly similar hardness values to those of high-calcium concentration prepared without CCS, but had higher cohesiveness. The high-calcium matrices containing CCS had quite a different microstructure and increased water mobility compared to those made without CCS and showed the slowest rate (p ≤ 0.05) of disintegration in the gastric environment. Gastric resistance was not affected by the type of lipid phase. Conversely, fatty acid release was similar for all emulsion gels prepared from milk fat, however, high-calcium emulsion gels (CCS-free) prepared from rapeseed oil showed higher lipolysis. Results suggest that food matrix physical properties can be modified to alter resistance to gastric degradation which may have consequences for the kinetics of nutrient release and delivery of bioactives sensitive to the gastric environment.

  1. Effect of calcium on adsorptive removal of As(III) and As(V) by iron oxide-based adsorbents

    KAUST Repository

    Uwamariya, V.

    2014-06-25

    The effects of calcium on the equilibrium adsorption capacity of As(III) and As(V) onto iron oxide-coated sand (IOCS) and granular ferric hydroxide (GFH) were investigated through batch experiments, rapid small-scale column tests (RSSCT) and kinetics modelling. Batch experiments showed that at calcium concentrations≤20 mg/L, high As(III) and As(V) removal efficiencies by IOCS and GFH are achieved at pH 6. An increase of the calcium concentration to 40 and 80 mg/L reversed this trend, giving higher removal efficiencies at higher pH (8). The adsorption capacities of IOCS and GFH at an equilibrium arsenic concentration of 10 g/L were found to be between 2.0 and 3.1 mg/g for synthetic water without calcium and between 2.8 and 5.3 mg/g when 80 mg/L of calcium was present at the studied pH values. After 10 hours of filter run in RSSCT, approximately 1000 empty bed volumes, the ratios of C/Co for As(V) were 26% and 18% for calcium-free model water; and only 1% and 0.2% after addition of 80 mg/L of Ca for filter columns with IOCS and GFH, respectively. The adsorption of As(III) and As(V) onto GFH follows a second-order reaction, with and without addition of calcium. The adsorption of As(III) and As(V) onto IOCS follows a first-order reaction without calcium addition, and moves to the second-reaction-order kinetics when calcium is added. Based on the intraparticle diffusion model, the main controlling mechanism for As(III) adsorption is intraparticle diffusion, while surface diffusion contributes greatly to the adsorption of As(V).

  2. Electrochemical characterization of calcium cobaltite based porous electrodes; Caracterizacao eletroquimica de eletrodos porosos a base de cobaltita de calcio

    Energy Technology Data Exchange (ETDEWEB)

    Fulgencio, E.B.G.A.; Vasconcelos, K.; Silva, R.M.; Melo, P.; Caetano, A.A.; Campos, L.F.A.; Dutra, R.P.S.; Macedo, D.A., E-mail: erikbgrisi@gmail.com [Universidade Federal da Paraiba (UFPB), PB (Brazil)

    2016-07-01

    Materials based on alkali metal oxides and alkaline earth metal have shown high technological interest in recent years. Among these materials, calcium and cobalt oxide composition Ca{sub 3}Co{sub 4}O{sub 9} (C349) has emerged as thermoelectric material and, more recently, as cathode for solid oxide fuel cell (SOFC). In this study, C349 powder was obtained by solid state reaction of a mixture containing cobalt oxide and calcium carbonate from shellfish shells (CaCO{sub 3} ∼ 98%), previously calcined at 550° C. Symmetrical cells (cathode / substrate / cathode) were prepared by screen printing of C349 electrodes in gadolinium-doped ceria substrates. The characterization by electrochemical impedance spectroscopy revealed that the C349 obtained in this work has an area specific resistance compatible with electrodes obtained by chemical routes (from literature). (author)

  3. Preparation of hard magnetic materials based on nitrogenated rare-earth iron alloys; Preparacao de materiais magneticamente duros a base de ligas de terra rara - ferro nitrogenadas

    Energy Technology Data Exchange (ETDEWEB)

    Guilherme, Eneida da Graca

    1999-07-01

    Nd Fe{sub 11}Ti, Nd Fe{sub 10.5} Mo{sub 1.5} and Nd Fe{sub 10.75} Mo{sub 1.25} alloys were synthesized by reduction-diffusion calciothermic process (RDC) from neodymium chloride (NdCl{sub 3}), iron, titanium, molybdenum and reduction agent (metallic calcium). The effect of process variables, like temperature, time, excess amount of NdCl{sub 3}, heating rate, and composition variation of the Nd Fe{sub 12-x}Mo{sub x} (1 {>=} x {>=} 2). Mother alloys in which 1:12 phase is major were nitrogenated by gas-solid reaction with N{sub 2} and by chemical reaction with sodium zide (Na N{sub 3}). In addition, the influence of reducing particle size of the powdered mother alloys in the nitrogenation step with Na N{sub 3} were studied. As prepared and interstitially modified Nd Fe{sub 11} Ti, Nd Fe{sub 10.5} Mo{sub 1.5} and Nd Fe{sub 10.75} Mo{sub 1.25} alloys with nitrogen , were characterized by X-ray diffraction, Moessbauer spectroscopy, thermomagnetic, SEM and EDS. Nitrogenation by gas-solid reaction with N{sub 2} is found to be not promising, since resulted Curie temperatures (Tc) were lower than literature values. However, nitrogenation by chemical reaction with Na N{sub 3} was efficient with higher or same Tc than previous reported results. The average increases on Tc and volumetric expansion were 200 deg C and 4%, respectively. Milling of the mother alloys before nitrogenation at 330 deg C is preferred because reaction kinetics is enhanced. Nevertheless, at 450 deg C, a competition between the interstitially modified compound formation (alloy + N) and alloy dissociation has occurred, resulting in a Fe-{alpha} phase increase. (author)

  4. Preparation and microstructure of laser-glazed Al-based alloys. Herstellung und Gefuege von laserverglasten Al-basis-legierungen

    Energy Technology Data Exchange (ETDEWEB)

    Jost, N. (Wiernsheim und Materialpruefanstalt der DEKRA-ETS mbH, Saarbruecken (Germany))

    1994-09-01

    From the metallurgical as well as from the economic/industrial point of view the laser glazing of Al-based alloys represents a new and at the same time increasing interesting field. If it could be possible to vitrify low-price and suitable Al-alloys with laser light, this could open attractive fields of application, especially for wear-resisting parts (for example in engines). Based on a short discussion of the most important metallurgical aspects which occur during the laser treatment like rapid melting, mixing and rapid quenching the potentiality and limits of laser amorphization of Al alloys will be analyzed. Thereby, the results of experiments with Al-Y-Ni alloys are of special interest. It will be shown that it is possible to vitrify the surface if the process parameters and the pretreatment of the material are well chosen. In this case the maximum hardness amounts to 1000 HV 0.025. (orig.)

  5. Effect of composition and particle morphology on the electrochemical properties of LaNi{sub 5}-based alloy electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Spodaryk, Mariana, E-mail: poshtamary@ukr.net [Institute for Problems of Materials Science, NAS of Ukraine, 3 Krzhyzhanovsky Str., 03680 Kyiv-142 (Ukraine); Shcherbakova, Larisa; Sameljuk, Anatoly [Institute for Problems of Materials Science, NAS of Ukraine, 3 Krzhyzhanovsky Str., 03680 Kyiv-142 (Ukraine); Zakaznova-Herzog, Valentina; Braem, Beat; Holzer, Marco; Mauron, Philippe; Remhof, Arndt [Division ‘Hydrogen and Energy’, EMPA Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf (Switzerland); Solonin, Yurii [Institute for Problems of Materials Science, NAS of Ukraine, 3 Krzhyzhanovsky Str., 03680 Kyiv-142 (Ukraine); Züttel, Andreas [Division ‘Hydrogen and Energy’, EMPA Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf (Switzerland)

    2014-09-01

    Highlights: • Characteristics of Al and Co in substituted gas-atomised alloy electrodes is shown. • Surface composition determines the kinetics and stability of the electrodes. • Corrosion of the Al leads to faster kinetics as compared to the Co-containing alloys. - Abstract: Al and Co substituted LaNi{sub 5}-based intermetallic compounds were investigated as negative electrode materials in alkaline KOH-electrolyte. The structure, morphology and electrochemical properties of gas-atomised and cast LaNi{sub 4.5}Al{sub 0.5} and LaNi{sub 2.5}Co{sub 2.4}Al{sub 0.1} alloys were investigated and the effect of the substitutions and the production method on the surface and bulk composition is compared to cast LaNi{sub 5} as a reference. While the rapid solidification of the gas-atomised alloys affects the site energy distribution for hydrogen on the interstitial sites, the activation and degradation mechanism of the electrodes cycle life is dominated by the elemental composition of the alloy and especially the surface. Therefore, the alloys with the larger Al content activate within a few cycles and also degrade faster as compared to the alloys with a high Co content. Furthermore, the dissolution of Al leads to a highly active surface with a lower reaction resistance, which leads to an order of magnitude increased high rate dischargeability.

  6. Base-metal dental casting alloy biocompatibility assessment using a human-derived three-dimensional oral mucosal model.

    LENUS (Irish Health Repository)

    McGinley, E L

    2012-01-01

    Nickel-chromium (Ni-Cr) alloys used in fixed prosthodontics have been associated with type IV Ni-induced hypersensitivity. We hypothesised that the full-thickness human-derived oral mucosa model employed for biocompatibility testing of base-metal dental alloys would provide insights into the mechanisms of Ni-induced toxicity. Primary oral keratinocytes and gingival fibroblasts were seeded onto Alloderm™ and maintained until full thickness was achieved prior to Ni-Cr and cobalt-chromium (Co-Cr) alloy disc exposure (2-72 h). Biocompatibility assessment involved histological analyses with cell viability measurements, oxidative stress responses, inflammatory cytokine expression and cellular toxicity analyses. Inductively coupled plasma mass spectrometry analysis determined elemental ion release levels. We detected adverse morphology with significant reductions in cell viability, significant increases in oxidative stress, inflammatory cytokine expression and cellular toxicity for the Ni-Cr alloy-treated oral mucosal models compared with untreated oral mucosal models, and adverse effects were increased for the Ni-Cr alloy that leached the most Ni. Co-Cr demonstrated significantly enhanced biocompatibility compared with Ni-Cr alloy-treated oral mucosal models. The human-derived full-thickness oral mucosal model discriminated between dental alloys and provided insights into the mechanisms of Ni-induced toxicity, highlighting potential clinical relevance.

  7. Oxidation behavior of FeCr and FeCrY alloys coated with an aluminium based paint

    Directory of Open Access Journals (Sweden)

    Marina Fuser Pillis

    2008-09-01

    Full Text Available A variety of metallic components rely on properties that are specific to the alloy and its surface. Coatings have been extensively used to protect metallic surfaces from the aggressive effects of the environment to which it is exposed. In this investigation, the high temperature oxidation behavior of a FeCr and a FeCrY alloy coated with an aluminium based paint has been studied. The objective was to form the more resistant alumina surface layer on an aluminium free alloy. Aluminium based paint coated and uncoated specimens of the two alloys were oxidized for up to 200 hours at 1000 °C in air. The oxidized specimens were examined in a scanning electron microscope coupled to an energy dispersive system and the surfaces were analyzed by X ray diffraction analysis. The aluminium based paint coating increased the oxidation resistance of the alloys, mainly over extended periods. The FeCrY alloy coated with the Al based paint exhibited the highest oxidation resistance.

  8. Recent progress on the hydrogen storage properties of ZrCo-based alloys applied in International Thermonuclear Experimental Reactor (ITER

    Directory of Open Access Journals (Sweden)

    Feng Wang

    2017-02-01

    Full Text Available Under the development of International Thermonuclear Experimental Reactor (ITER system aimed at realizing the controllable fusion reaction to solve the energy crisis fundamentally, there is an urgent need to find an appropriate material for tritium handling. ZrCo alloy is considered to be a promising candidate for the storage and delivery of hydrogen isotopes due to the favorable characteristics such as low plateau pressure for absorption, high dissociation pressure at moderate temperature and better ability of trapping 3He. However, the hydrogen induced disproportionation and the slower recovery/deliverty rate of ZrCo-based alloys have limited their further application in ITER system. This review summarizes the efforts towards enhancing the hydrogen storage properties of ZrCo-based alloys including element substitution, surface modification, disproportionation mechanism investigation and the isotope effect study. Element substitution and surface modification play positive role to improve the anti-disproportionation ability and kinetic property of the alloys. However, the ZrCo-based alloys require to be further modified by more attempts such as new composition, novelty modification method or catalyst addition in order to better satisfy the application demands for tritium handling. Moreover, new insight for further understanding the inner disproportionation mechanisms of this material is needed by combining the advance characterization and theoretical analysis, which is in favor of addressing the disproportionation problem of the ZrCo-based alloys essentially.

  9. Composition Optimization of Lithium-Based Ternary Alloy Blankets for Fusion Reactors

    Science.gov (United States)

    Jolodosky, Alejandra

    The goal of this dissertation is to examine the neutronic properties of a novel type of fusion reactor blanket material in the form of lithium-based ternary alloys. Pure liquid lithium, first proposed as a blanket for fusion reactors, is utilized as both a tritium breeder and a coolant. It has many attractive features such as high heat transfer and low corrosion properties, but most importantly, it has a very high tritium solubility and results in very low levels of tritium permeation throughout the facility infrastructure. However, lithium metal vigorously reacts with air and water and presents plant safety concerns including degradation of the concrete containment structure. The work of this thesis began as a collaboration with Lawrence Livermore National Laboratory in an effort to develop a lithium-based ternary alloy that can maintain the beneficial properties of lithium while reducing the reactivity concerns. The first studies down-selected alloys based on the analysis and performance of both neutronic and activation characteristics. First, 3-D Monte Carlo calculations were performed to evaluate two main neutronics performance parameters for the blanket: tritium breeding ratio (TBR), and energy multiplication factor (EMF). Alloys with adequate results based on TBR and EMF calculations were considered for activation analysis. Activation simulations were executed with 50 years of irradiation and 300 years of cooling. It was discovered that bismuth is a poor choice due to achieving the highest decay heat, contact dose rates, and accident doses. In addition, it does not meet the waste disposal ratings (WDR). The straightforward approach to obtain Monte Carlo TBR and EMF results required 231 simulations per alloy and became computationally expensive, time consuming, and inefficient. Consequently, alternate methods were pursued. A collision history-based methodology recently developed for the Monte Carlo code Serpent, calculates perturbation effects on practically

  10. Effect of directional solidification on the structure and properties of Ni3Al-based alloy single crystals alloyed with Cr, Mo, W, Ti, Co, Re, and REM

    Science.gov (United States)

    Povarova, K. B.; Bondarenko, Yu. A.; Drozdov, A. A.; Bazyleva, O. A.; Antonova, A. V.; Morozov, A. E.; Arginbaeva, E. G.

    2015-01-01

    The effect of the solidification rate ( R = 2, 5, 10, 20 mm/min) at the same solidification gradient ( G = 150°C/cm) on the structural parameters of single-crystal blade workpieces made of an alloy based on the γ'(Ni3Al) intermetallic compound and alloyed with cobalt and rhenium apart from chromium, molybdenum, titanium, and rare-earth metal microadditions is studied. The single crystals have a dendritic-cellular structure. Primary γ'-phase precipitates are observed in the interdendritic space of heterophase γ' + γ dendrites. An increase in the solidification rate from 2 to 20 mm/min at a solidification gradient of 150°C/min leads to refinement of all structural constituents by a factor of 1.5-2, with the morphology and the mutual position of the structural constituents being independent of the solidification rate. In experiments with moderate additional alloying with cobalt and rhenium, the yield strength increases by 10-20% and the long-term strength increases by at least 20-25% at a temperature of 900 and 1100°C upon holding for 100 and 500 h. The VKNA-25 alloy single crystals have moderate plasticity (δ = 6-20%) over the entire temperature range (20-1200°C) and have no sharp increase in the plasticity characteristic of a VKNA-1V alloy without cobalt and rhenium. During long-term tests, local raft structure regions misoriented with respect to the tension direction form in γ' + γ dendrites. γ'-Phase nanoparticles precipitate in the γ layers. During tests, refractorymetal-rich nanoparticles of a predominantly acicular-lamellar shape precipitate in dendrite arms.

  11. Mg-based amorphous alloys for decolorization of azo dyes

    Science.gov (United States)

    Zhang, Changqin; Zhu, Zhengwang; Zhang, Haifeng

    The authors recently found that Mg-based amorphous ribbons had a prominent effect on the decolorization of azo dyes. Direct Blue 2B and Acid Orange II solutions of 100 mg/L could be decolorized nearly completely by the ribbons within 30 min. Decolorization mechanism was discussed briefly, and kinetic analysis based on the experimental data indicated that physical adsorption and reductive degradation for the azo dye solutions mediated by Mg63Cu16.8Ag11.2Er9 amorphous ribbons could proceed in an elegant and rapid manner. This new finding seems attractive, valuable and promising for the raw effluent generated by textile dye manufacturing company in the future.

  12. Effects of Leaching Behavior of Calcium Ions on Compression and Durability of Cement-Based Materials with Mineral Admixtures

    Science.gov (United States)

    Cheng, An; Chao, Sao-Jeng; Lin, Wei-Ting

    2013-01-01

    Leaching of calcium ions increases the porosity of cement-based materials, consequently resulting in a negative effect on durability since it provides an entry for aggressive harmful ions, causing reinforcing steel corrosion. This study investigates the effects of leaching behavior of calcium ions on the compression and durability of cement-based materials. Since the parameters influencing the leaching behavior of cement-based materials are unclear and diverse, this paper focuses on the influence of added mineral admixtures (fly ash, slag and silica fume) on the leaching behavior of calcium ions regarding compression and durability of cemented-based materials. Ammonium nitrate solution was used to accelerate the leaching process in this study. Scanning electron microscopy, X-ray diffraction analysis, and thermogravimetric analysis were employed to analyze and compare the cement-based material compositions prior to and after calcium ion leaching. The experimental results show that the mineral admixtures reduce calcium hydroxide quantity and refine pore structure through pozzolanic reaction, thus enhancing the compressive strength and durability of cement-based materials. PMID:28809247

  13. Magnesium-Based Sacrificial Anode Cathodic Protection Coatings (Mg-Rich Primers for Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    Michael D. Blanton

    2012-09-01

    Full Text Available Magnesium is electrochemically the most active metal employed in common structural alloys of iron and aluminum. Mg is widely used as a sacrificial anode to provide cathodic protection of underground and undersea metallic structures, ships, submarines, bridges, decks, aircraft and ground transportation systems. Following the same principle of utilizing Mg characteristics in engineering advantages in a decade-long successful R&D effort, Mg powder is now employed in organic coatings (termed as Mg-rich primers as a sacrificial anode pigment to protect aerospace grade aluminum alloys against corrosion. Mg-rich primers have performed very well on aluminum alloys when compared against the current chromate standard, but the carcinogenic chromate-based coatings/pretreatments are being widely used by the Department of Defense (DoD to protect its infrastructure and fleets against corrosion damage. Factors such as reactivity of Mg particles in the coating matrix during exposure to aggressive corrosion environments, interaction of atmospheric gases with Mg particles and the impact of Mg dissolution, increases in pH and hydrogen gas liberation at coating-metal interface, and primer adhesion need to be considered for further development of Mg-rich primer technology.

  14. Coupling Inward Diffusion and Precipitation Kinetics; the Case of Nitriding Iron-Based Alloys

    Science.gov (United States)

    Jung, Minsu; Meka, Sai Ramudu; Rheingans, Bastian; Mittemeijer, Eric Jan

    2016-03-01

    A model that describes the inward diffusion of an element I into a solid substrate and the simultaneous precipitation of a compound M y I z , with M as the alloying element initially dissolved in the substrate matrix, is presented for the case of nitriding iron-based alloys. The model was developed by coupling the diffusion kinetics and the precipitation (nucleation and growth) kinetics. Additionally, the role of excess nitrogen and the kinetics of ammonia dissociation at the iron surface were incorporated into this coupled model. The model was successfully applied to the case of nitriding an Fe-2.23 at. pct V alloy; the simulation results are in good agreement with the measured data and allow for detailed understanding of the evolution of the nitride precipitates (volume fraction, number density, and size distribution) as a function of both nitriding time and depth in the specimen. The present model exposed the pronounced effects of the precipitation kinetics, of excess nitrogen, and of the surface-reaction kinetics on the overall nitriding kinetics and demonstrated a striking, nonmonotonous change with time of precipitate particle size at a distinct depth in the specimen.

  15. Preparation of tantalum-based alloys by a unique CVD process

    Science.gov (United States)

    Bryant, W. A.; Meier, G. H.

    1975-01-01

    The paper describes a sequential pulsing technique for deposition of refractory alloys and evaluates the technique for the deposition of the tantalum-base alloys Ta-10W (Ta-10 st% W) and T-111 (Ta-8 wt% W-2 wt% Hf). The deposition cycle for Ta-10W was chosen as alternate injections of TaCl5 plus hydrogen and WCl6 plus hydrogen. The cycle for T-111 was chosen as injections of TaCl5 plus hydrogen interspersed with injections of WCl6 plus hydrogen. A temperature range of 900-1300 C was chosen for both alloys. The ability of the pulse process to blanket a uniformly heated section of substrate with a mixture of gases, whose composition varies not with position on the substrate but instead with time of residence in the reactor, allows metal of uniform thickness to be deposited. It is shown that Ta and W can be deposited at high temperature with the formation of a dense columnar grain structure, so that the feasibility of preparing uniformly thick deposits of these elements by a 'pulsing' modification of CVD is demonstrated. A similar attempt to deposit T-111 was unsuccessful due to the difficulty in reducing HfCl4.

  16. Impact properties of vanadium-base alloys irradiated at < 430 C

    Energy Technology Data Exchange (ETDEWEB)

    Chung, H.M.; Smith, D.L. [Argonne National Lab., IL (United States)

    1998-03-01

    Recent attention to vanadium-base alloys has focused on the effect of low-temperature (<430 C) neutron irradiation on the mechanical properties, especially the phenomena of loss of work-hardening capability under tensile loading and loss of dynamic toughness manifested by low impact energy and high ductile-brittle-transition temperature (DBTT). This paper summarizes results of an investigation of the low-temperature impact properties of V-5Ti, V-4Cr-4Ti, and V-3Ti-Si that were irradiated in several fission reactor experiments, i.e., FFTF-MOTA, EBR-II X-530, and ATR-A1. Irradiation performance of one production-scale and one laboratory heat of V-4C-4Ti and one laboratory heat of V-3Ti-Si was the focus of the investigation. Even among the same lass of alloy, strong heat-to-heat variation was observed in low-temperature impact properties. A laboratory heat of V-4Cr-4Ti and V-3Ti-1Si exhibited good impact properties whereas a 500-kg heat of V-4Cr-4Ti exhibited unacceptably high DBTT. The strong heat-to-heat variation in impact properties of V-4Cr-4Ti indicates that fabrication procedures and minor impurities play important roles in the low-temperature irradiation performance of the alloys.

  17. Computational thermodynamics and kinetics of displacive transformations in titanium-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Jia-Yi, E-mail: jiayiyan@kth.se [Department of Materials Science and Engineering, KTH Royal Institute of Technology, Brinellvägen 23, SE-100 44, Stockholm (Sweden); Olson, G.B., E-mail: g-olson@northwestern.edu [Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, IL, 60208-3108 (United States)

    2016-07-15

    The thermodynamics of Ti-based systems are described for β–α′/α″ martensitic transformation and athermal ω formation at low temperatures. The new descriptions can better represent the relationship between the partitionless equilibrium temperature and the measured martensite-formation/reversion temperatures. The anomalous β-stabilizing effects of Al, Sn, and Zr in ternary Ti–V/Nb-based alloys are well modeled for the first time. The Gibbs energy function of ω–Ti at ambient pressure is assessed. The formation temperature of athermal ω phase is assessed in some binary systems and estimated in some ternary systems based on electrical resistivity and first-principles calculations. The critical driving force for heterogeneous martensitic nucleation is modeled by solution-hardening interfacial friction using the present thermodynamic descriptions. The competition between martensite and athermal ω phase can be understood based on their transformation thermodynamic and kinetic factors. - Highlights: • The thermodynamics of low-temperature displacive transformations in Ti-based systems are described. • The anomalous β-stabilizing effects of Al, Sn, and Zr are correctly modeled for the first time in Ti–V/Nb-based systems. • The critical driving force of martensitic nucleation in Ti-based alloy is modeled by solution-hardening interfacial friction.

  18. Swelling in commercial Fe-Cr-Ni based alloys under electron irradiation

    Science.gov (United States)

    Thomas, L. E.; Gelles, D. S.

    1982-08-01

    Electron irradiation in a 1 MeV electron microscope has been used to study the void swelling response of several commercial austenitic stainless steels and iron-nickel based superalloys. Use of the 1 MeV microscope permits direct, continuous observation of the void development during elevated-temperature irradiations at displacement rates about 10 000 times greater then those in a fast breeder reactor. The alloys examined in this work included AISI 310, RA 330, A286, M813, Nimonic PE16, Inconel 706, Inconel 718 and Incoloy 901. Both helium preinjected specimens and uninjected specimens were studied. In all of the above alloys, swelling proceeds by formation of irradiation-induced dislocations and voids, followed by growth of the voids. The swelling rates and peak swelling temperatures vary considerably with alloy composition, heat treatment and helium preinjection. Comparisons of these results with recently reported swelling data from the same alloys after high fluence neutron irradiation in the EBR-II reactor shows good qualitative agreement in most cases. Helium preinjection of the electron irradiated specimens generally produced a poorer simulation than no helium preinjection. In one or two cases where the electron and neutron irradiation results strongly disagree, the differences appear to result from differences in irradiation-induced precipitation. Although the correlations between neutron and electron irradiation results are inadequate to obtain reliable engineering data by simulation, in-reactor swelling behavior is in general qualitatively well-represented by swelling response in the 1 MeV electron microscope. Nimonic is the registered trademark of Henry Wiggin and Company, UK. Inconel and Incoloy are registered trademarks of the International Nickel Company, Inc.

  19. Structural and mechanical characteristics of some lead-free Cu-Sn based solder alloys

    Directory of Open Access Journals (Sweden)

    Mitovski Aleksandra M.

    2008-01-01

    Full Text Available The results of structural and mechanical characteristics of lead-free Cu-Sn based solder alloys, produced in Company "11. mart" AD Srebrenica (Republic of Srpska, are presented in this paper. The results of investigation of samples - alloys CuSnl4, CuSnlFelAlO.5, CuSnlOFelAllMnO.5 and CuA110Fe3Mn produced by different processing methods, include the data obtained by optical microscopy and measurements of hardness, micro hardness and electroconductivity, in order to characterize mentioned alloys and define the influence of processing method applied on their structural and mechanical properties. Microstructural experimental results of samples produced by casting in a metal mould with fast water cooling showed clearly sharp dendritic structure. Samples obtained by casting in a sand mould, displayed structure with big crystals, higher amount of segregation and inclusions on the grain boundaries, as a result of the slow cooling process. Hardness and microhardness tests showed increasing values as the amount of tin raised. Sample 3 showed the lowest value, as a result of the crystallization process and lackness of additional thermal treatment. Experimental results of the electroconductivity test showed that mentioned sample has got the highest value, which can be also explained by its production method. Results presented in this paper can contribute to investigations of copper-tin lead-free alloys, having in mind that various potential lead-free solders still haven't been completely investigated from the aspects of their structural, mechanical and electrical properties.

  20. Comparison of the bond strength of laser-sintered and cast base metal dental alloys to porcelain.

    Science.gov (United States)

    Akova, Tolga; Ucar, Yurdanur; Tukay, Alper; Balkaya, Mehmet Cudi; Brantley, William A

    2008-10-01

    The purpose of this study was to compare shear bond strengths of cast Ni-Cr and Co-Cr alloys and the laser-sintered Co-Cr alloy to dental porcelain. Dental porcelain was applied on two cast and one laser-sintered base metal alloy. Ten specimens were prepared for each group for bond strength comparison. ANOVA followed by Tukey HSD multiple comparison test (alpha=0.05) was used for statistical analysis. Fractured specimens were observed with a stereomicroscope to classify the type of failure after shear bond testing. While the mean shear bond strength was highest for the cast Ni-Cr metal-ceramic specimens (81.6+/-14.6 MPa), the bond strength was not significantly different (P>0.05) from that for the cast Co-Cr metal-ceramic specimens (72.9+/-14.3 MPa) and the laser-sintered Co-Cr metal-ceramic specimens (67.0+/-14.9 MPa). All metal-ceramic specimens prepared from cast Ni-Cr and Co-Cr alloys exhibit a mixed mode of cohesive and adhesive failure, whereas five of the metal-ceramic specimens prepared from the laser-sintered Co-Cr alloy exhibited the mixed failure mode and five specimens exhibited adhesive failure in the porcelain. The new laser-sintering technique for Co-Cr alloy appears promising for dental applications, but additional studies of properties of the laser-sintered alloy and fit of castings prepared by this new technique are needed before its acceptance into dental laboratory practice. Laser sintering of Co-Cr alloy seems to be an alternative technique to conventional casting of dental alloys for porcelain fused to metal restorations.

  1. Catalytic activity of calcium-based mixed metal oxides nanocatalysts in transesterification reaction of palm oil

    Science.gov (United States)

    Hassan, Noraakinah; Ismail, Kamariah Noor; Hamid, Ku Halim Ku; Hadi, Abdul

    2017-12-01

    Nowadays, biodiesel has become the forefront development as an alternative diesel fuel derived from biological sources such as oils of plant and fats. Presently, the conventional transesterification of vegetable oil to biodiesel gives rise to some technological problem. In this sense, heterogeneous nanocatalysts of calcium-based mixed metal oxides were synthesized through sol-gel method. It was found that significant increase of biodiesel yield, 91.75 % was obtained catalyzed by CaO-NbO2 from palm oil compared to pure CaO of 53.99 % under transesterification conditions (methanol/oil ratio 10:1, reaction time 3 h, catalyst concentration 4 wt%, reaction temperature 60 °C, and mixing speed of 600 rpm). The phase structure and crystallinity as well as the texture properties of the prepared catalysts were characterized by X-ray Diffraction (XRD) and the textural properties were characterized by N2 adsorption-desorption analysis. Sol-gel method has been known as versatile method in controlling the structural and chemical properties of the catalyst. Calcium-based mixed oxide synthesized from sol-gel method was found to exist as smaller crystallite size with high surface area.

  2. Catalytic pyrolysis of wood biomass in an auger reactor using calcium-based catalysts.

    Science.gov (United States)

    Veses, A; Aznar, M; Martínez, I; Martínez, J D; López, J M; Navarro, M V; Callén, M S; Murillo, R; García, T

    2014-06-01

    Wood catalytic pyrolysis using calcium-based materials was studied in an auger reactor at 450°C. Two different catalysts, CaO and CaO·MgO were evaluated and upgraded bio-oils were obtained in both cases. Whilst acidity and oxygen content remarkable decrease, both pH and calorific value increase with respect to the non-catalytic test. Upgrading process was linked to the fact that calcium-based materials could not only fix the CO2-like compounds but also promoted the dehydration reactions. In addition, process simulation demonstrated that the addition of these catalysts, especially CaO, could favour the energetic integration since a lowest circulation of heat carrier between combustor and auger reactor should be needed. An energy self-sustained system was obtained where thermal energy required for biomass drying and for pyrolysis reaction was supplied by non-condensable gas and char combustion, respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Shear bond strength of novel calcium aluminate-based cement (EndoBinder) to root dentine

    Science.gov (United States)

    Garcia, Lucas da Fonseca Roberti; Rossetto, Hebert Luis; Pires-de-Souza, Fernanda de Carvalho Panzeri

    2014-01-01

    Objective: To evaluate the shear bond strength of a novel calcium aluminate-based cement, EndoBinder (EB), to dentine in comparison with Grey and White Mineral Trioxide Aggregate (MTA). Materials and Methods: Root canal hemi-sections obtained from 30 extracted molar teeth were embedded in self-polymerized acrylic resin and were grounded wet in order to obtain a flat dentine surface. Next, the roots were randomly assigned into three groups (n = 10), according to the cement used, as follows: EB: EndoBinder; WMTA: White MTA and GMTA: Grey MTA. The shear bond strength test was performed using a Universal Testing Machine (0.5 mm/min) and the data were submitted to statistical analysis (1-way ANOVA and Tukey tests, P 0.05). WMTA presented the lowest mean values, which were significant in comparison with EB (P < 0.05). Conclusions: The novel calcium aluminate-based cement presented higher shear bond strength than WMTA, and should be considered as a promising alternative in endodontic therapy. PMID:25512731

  4. Biocompatibility of a new nanomaterial based on calcium silicate implanted in subcutaneous connective tissue of rats

    Directory of Open Access Journals (Sweden)

    Petrović Violeta

    2012-01-01

    Full Text Available The aim of the study was to investigate rat connective tissue response to a new calcium silicate system 7, 15, 30 and 60 days after implantation. Twenty Wistar albino male rats received two tubes half-filled with a new calcium silicate system (NCSS or MTA in subcutaneous tissue. The empty half of the tubes served as controls. Five animals were sacrificed after 7, 15, 30 and 60 days and samples of the subcutaneous tissue around implanted material were submitted to histological analysis. The intensity of inflammation was evaluated based on the number of inflammatory cells present. Statistical analysis was performed using one way ANOVA and Holm Sidak's multiple comparison tests. Mild to moderate inflammatory reaction was observed after 7, 15 and 30 days around a NCSS while mild inflammatory reaction was detected after 60 days of implantation. In the MTA group, mild to moderate inflammatory reaction was found after 7 and 15 days while mild inflammatory reaction was present after 30 and 60 days. There was no statistically significant difference in the intensity of inflammatory reactions between the tested materials and control groups in any experimental period (ANOVA p>0.05. Regarding the intensity of inflammatory reactions at different experimental periods, a statistically significant difference was observed between 7 and 30 days, 7 and 60 days and 15 to 60 days for both materials. For the controls, a statistically significant difference was found between 7 and 60 days and 15 and 60 days of the experiment (Holm Sidak < p 0.001. Subcutaneous tissue of rats showed good tolerance to a new calcium silicate system. Inflammatory reaction was similar to that caused by MTA. [Projekat Ministarstva nauke Republike Srbije, br. 172026

  5. As-cast microstructures and behavior at high temperature of chromium-rich cobalt-based alloys containing hafnium carbides

    Energy Technology Data Exchange (ETDEWEB)

    Berthod, Patrice, E-mail: Patrice.Berthod@univ-lorraine.fr; Conrath, Elodie

    2014-02-14

    Hafnium is often used to improve the high temperature oxidation resistance of superalloys but not to form carbides for strengthen them against creep. In this work hafnium was added in cobalt-based alloys for verifying that HfC can be obtained in cobalt-based alloys and for characterizing their behavior at a very temperature. Three Co–25Cr–0.25 and 0.50C alloys containing 3.7 and 7.4 Hf to promote HfC carbides, and four Co–25Cr– 0 to 1C alloys for comparison (all contents in wt.%), were cast and exposed at 1200 °C for 50 h in synthetic air. The HfC carbides formed instead chromium carbides during solidification, in eutectic with matrix and as dispersed compact particles. During the stage at 1200 °C the HfC carbides did not significantly evolve, even near the oxidation front despite oxidation early become very fast and generalized. At the same time the chromium carbides present in the Co–Cr–C alloys totally disappeared in the same conditions. Such HfC-alloys potentially bring efficient and sustainable mechanical strengthening at high temperature, but their hot oxidation resistance must be significantly improved. - Highlights: • Co-based alloys containing HfC carbides were successfully obtained by foundry. • HfC are pro-eutectic or form an interdendritic eutectic compound with matrix. • The HfC carbides appear very stable on long time at 1200 °C. • The hot oxidation of the alloys is fast and they require higher Cr contents. • The high stability of HfC may allow Cr-enrichment by pack-cementation.

  6. Reactivity classification in saline solution of magnetron sputtered or EBPVD pure metallic, nitride and Al-based alloy coatings

    Energy Technology Data Exchange (ETDEWEB)

    Creus, J., E-mail: jcreus@univ-lr.fr [LEMMA, Universite de la Rochelle, Av. Michel Crepeau, F-17042 La Rochelle Cdx (France); Berziou, C.; Cohendoz, S.; Perez, A.; Rebere, C.; Reffass, M.; Touzain, S. [LEMMA, Universite de la Rochelle, Av. Michel Crepeau, F-17042 La Rochelle Cdx (France); Allely, C. [Arcelor Mittal, Voie Romaine, BP 30320, F-57283 Maizieres les Metz Cdx (France); Gachon, Y.; Heau, C. [HEF R and D, Rue Benoit Fourneyron, F-42166 Andrezieux Boutheon Cdx (France); Sanchette, F. [CEA Grenoble DRT/LITEN/DTMN/LTS, 17 rue des Martyrs, F-38054 Grenoble (France); LERMPS, UTBM, F-90010 Belfort (France); Billard, A. [LERMPS, UTBM, F-90010 Belfort (France)

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer Morphological and structural characterisation of metals and alloys deposited by PVD. Black-Right-Pointing-Pointer Electrochemical reactivity of Al-based alloys in saline solution. Black-Right-Pointing-Pointer Influence of incorporation of transition metals on the pitting corrosion of aluminium. Black-Right-Pointing-Pointer Reactivity classification of Al coatings deposited by vacuum deposition techniques. Black-Right-Pointing-Pointer Classification of mechanical properties in terms of micro-hardness measurements. - Abstract: In this study, various metallic or nitride coatings elaborated by Electron Beam Physical Vapour Deposition (EBPVD) or magnetron sputtering techniques are characterised in terms of mechanical properties and corrosion behaviour in saline solution. The incorporation of transition metals permits to modify the mechanical or physico-chemical characteristics of aluminium coatings, so several alloying elements are compared. These alloys are also compared with pure metallic coatings and/or coatings synthesized by reactive magnetron sputtering. Evolution of microstructure of the Al based coatings was discussed versus the alloying element content. Different compositions of alloys were examined. This paper presents the synthesis of the main tendency reported during the evaluation of the mechanical and corrosion properties of these alloys. The objective is to build a reactivity classification in saline solution of several Al based coatings synthesized by vacuum deposition techniques. Combined with the classification of mechanical properties, these standards would become relevant guides in the choice of PVD coatings and/or alloys for applications exposed to saline environments. In our study, this guide is helpful in the synthesis of nanometric multilayer architectures, which proves to be a promising way to combine improved mechanical properties with sacrificial character for the future coating configurations.

  7. A silanol-based nanocomposite coating for protection of AA-2024 aluminium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, E.; Pavez, J.; Azocar, I.; Zagal, J.H. [Departamento de Quimica de los Materiales, Facultad de Quimica y Biologia, Universidad de Santiago de Chile, Avenida Bernardo O' Higgins 3363, Casilla 40, Correo 33, Santiago (Chile); Zhou, X. [Corrosion and Protection Centre, School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); Melo, F. [Departamento de Fisica, Facultad de Ciencias, Universidad de Santiago de Santiago de Chile, Avenida Bernardo O' Higgins 3363, Santiago (Chile); Thompson, G.E. [Corrosion and Protection Centre, School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); Paez, M.A., E-mail: maritza.paez@usach.cl [Departamento de Quimica de los Materiales, Facultad de Quimica y Biologia, Universidad de Santiago de Chile, Avenida Bernardo O' Higgins 3363, Casilla 40, Correo 33, Santiago (Chile)

    2011-09-01

    Highlights: {center_dot} A new silanol-based hybrid coating has been synthesized. {center_dot} The incorporation of CeO{sub 2} and ZrO{sub 2} nanoparticles into the coating greatly improves the corrosion resistance of the coated aluminium alloy. {center_dot} The effectiveness of the coating is increasingly evident for long term exposure to the sodium chloride solution. {center_dot} The silanol-based nanocomposite coatings have self-healing ability. - Abstract: A new hybrid sol-gel type film, composed of tetraethylorthosilicate (TEOS) and tetraocthylorthosilicate (TEOCS), and modified with different nanoparticle systems, has been investigated as a coating for protection of AA-2024-T3 aluminium alloy. The nanoparticle systems considered were either ZrO{sub 2} or CeO{sub 2} or their combination{sub .} The zirconia nanoparticles were prepared from a Zr (IV) propoxide sol (TPOZ), using an organic stabilizer, and the CeO{sub 2} nanoparticles were developed spontaneously after adding cerium nitrate solution to the hybrid sol. The chemical composition and the structure of the hybrid sol-gel films were examined by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The corrosion resistance of the coated AA-2024 alloy was examined by potentiodynamic polarization. The results revealed that, for short exposure times in the electrolyte, incorporation of ZrO{sub 2} or CeO{sub 2} nanoparticles in the hybrid film does not provide an increase in the corrosion resistance of the coated AA-2024 alloy. Further, the resistance was significantly reduced by increasing the nanoparticle content. Conversely, by incorporating both nanoparticles (ZrO{sub 2} and CeO{sub 2}), the corrosion resistance of the resulting hybrid films increased slightly. The behavior changed significantly when the coated alloy was exposed to the electrolyte for 5 days. The corrosion resistance of the coatings, unmodified and modified with CeO{sub 2} or Zr

  8. Development of Au-Ge based candidate alloys as an alternative to high-lead content solders

    DEFF Research Database (Denmark)

    Chidambaram, Vivek; Hald, John; Hattel, Jesper Henri

    2010-01-01

    Au-Ge based candidate alloys have been proposed as an alternative to high-lead content solders that are currently being used for high-temperature applications. The changes in microstructure and microhardness associated with the addition of low melting point metals namely In, Sb and Sn to the Au......-Ge eutectic were investigated in this work. Furthermore, the effects of thermal aging on the microstructure and its corresponding microhardness of these promising candidate alloys have been extensively reported. To investigate the effects of aging temperature, candidate alloys were aged at a lower temperature......, 150°C for up to 3 weeks and compared with aging at 200°C. After being subjected to high-temperature aging, the microstructure varied a lot in morphology in the case of both Au-Ge-Sb and Au-Ge-Sn candidate alloys while the microstructure remained relatively stable even after long-term thermal aging...

  9. High gas velocity oxidation and hot corrosion testing of oxide dispersion-strengthened nickel-base alloys

    Science.gov (United States)

    Deadmore, D. L.; Lowell, C. E.

    1975-01-01

    Several oxide dispersion strengthened (ODS) nickel-base alloys were tested in high velocity gases for cyclic oxidation resistance at temperatures to 1200 C and times to 500 hours and for hot corrosion resistance at 900 C for 200 hours. Nickel-chromium-aluminum ODS alloys were found to have superior resistance to oxidation and hot corrosion when compared to bare and coated nickel-chromium ODS alloys. The best of the alloys tested had compositions of nickel - 15.5 to 16 weight percent chromium with aluminum weight percents between 4.5 and 5.0. All of the nickel-chromium-aluminum ODS materials experienced small weight losses (less than 16 mg/sq cm).

  10. Serum calcium levels are associated with novel cardiometabolic risk factors in the population-based CoLaus study.

    Directory of Open Access Journals (Sweden)

    Idris Guessous

    Full Text Available BACKGROUND: Associations of serum calcium levels with the metabolic syndrome and other novel cardio-metabolic risk factors not classically included in the metabolic syndrome, such as those involved in oxidative stress, are largely unexplored. We analyzed the association of albumin-corrected serum calcium levels with conventional and non-conventional cardio-metabolic risk factors in a general adult population. METHODOLOGY/PRINCIPAL FINDINGS: The CoLaus study is a population-based study including Caucasians from Lausanne, Switzerland. The metabolic syndrome was defined using the Adult Treatment Panel III criteria. Non-conventional cardio-metabolic risk factors considered included: fat mass, leptin, LDL particle size, apolipoprotein B, fasting insulin, adiponectin, ultrasensitive CRP, serum uric acid, homocysteine, and gamma-glutamyltransferase. We used adjusted standardized multivariable regression to compare the association of each cardio-metabolic risk factor with albumin-corrected serum calcium. We assessed associations of albumin-corrected serum calcium with the cumulative number of non-conventional cardio-metabolic risk factors. We analyzed 4,231 subjects aged 35 to 75 years. Corrected serum calcium increased with both the number of the metabolic syndrome components and the number of non-conventional cardio-metabolic risk factors, independently of the metabolic syndrome and BMI. Among conventional and non-conventional cardio-metabolic risk factors, the strongest positive associations were found for factors related to oxidative stress (uric acid, homocysteine and gamma-glutamyltransferase. Adiponectin had the strongest negative association with corrected serum calcium. CONCLUSIONS/SIGNIFICANCE: Serum calcium was associated with the metabolic syndrome and with non-conventional cardio-metabolic risk factors independently of the metabolic syndrome. Associations with uric acid, homocysteine and gamma-glutamyltransferase were the strongest. These

  11. The Synthesis of Nanostructured WC-Based Hardmetals Using Mechanical Alloying and Their Direct Consolidation

    Directory of Open Access Journals (Sweden)

    N. Al-Aqeeli

    2014-01-01

    Full Text Available Tungsten carbide- (WC- based hardmetals or cemented carbides represent an important class of materials used in a wide range of industrial applications which primarily include cutting/drilling tools and wear resistant components. The introduction and processing of nanostructured WC-based cemented carbides and their subsequent consolidation to produce dense components have been the subject of several investigations. One of the attractive means of producing this class of materials is by mechanical alloying technique. However, one of the challenging issues in obtaining the right end-product is the possible loss of the nanocrystallite sizes due to the undesirable grain growth during powder sintering step. Many research groups have engaged in multiple projects aiming at exploring the right path of consolidating the nanostructured WC-based powders without substantially loosing the attained nanostructure. The present paper highlights some key issues related to powder synthesis and sintering of WC-based nanostructured materials using mechanical alloying. The path of directly consolidating the powders using nonconventional consolidation techniques will be addressed and some light will be shed on the advantageous use of such techniques. Cobalt-bonded hardmetals will be principally covered in this work along with an additional exposure of the use of other binders in the WC-based hardmetals.

  12. Laboratory study on the high-temperature capture of HCl gas by dry-injection of calcium-based sorbents.

    Science.gov (United States)

    Shemwell, B; Levendis, Y A; Simons, G A

    2001-01-01

    This is a laboratory study on the reduction of combustion-generated hydrochloric acid (HCl) emissions by in-furnace dry-injection of calcium-based sorbents. HCl is a hazardous gaseous pollutant emitted in significant quantities by municipal and hazardous waste incinerators, coal-fired power plants, and other industrial furnaces. Experiments were conducted in a laboratory furnace at gas temperatures of 600-1000 degrees C. HCl gas diluted with N2, and sorbent powders fluidized in a stream of air were introduced into the furnace concurrently. Chlorination of the sorbents occurred in the hot zone of the furnace at gas residence times approximately 1 s. The sorbents chosen for these experiments were calcium formate (CF), calcium magnesium acetate (CMA), calcium propionate (CP), calcium oxide (CX), and calcium carbonate (CC). Upon release of organic volatiles, sorbents calcine to CaO at approximately 700 degrees C, and react with the HCl according to the reaction CaO + 2HCl CaCl2 + H2O. At the lowest temperature case examined herein, 600 degrees C, direct reaction of HCl with CaCO3 may also be expected. The effectiveness of the sorbents to capture HCl was interpreted using the "pore tree" mathematical model for heterogeneous diffusion reactions. Results show that the thin-walled, highly porous cenospheres formed from the pyrolysis and calcination of CF, CMA, and CP exhibited high relative calcium utilization at the upper temperatures of this study. Relative utilizations under these conditions reached 80%. The less costly low-porosity sorbents, calcium carbonate and calcium oxide also performed well. Calcium carbonate reached a relative utilization of 54% in the mid-temperature range, while the calcium oxide reached an 80% relative utilization at the lowest temperature examined. The data matched theoretical predictions of sorbent utilization using the mathematical model, with activation energy and pre-exponential factors for the calcination reaction of 17,000 K and 300

  13. In situ Raman spectroscopic analysis of surface oxide films on Ni-base alloy/low alloy steel dissimilar metal weld interfaces in high-temperature water

    Science.gov (United States)

    Kim, Jongjin; Choi, Kyung Joon; Bahn, Chi Bum; Kim, Ji Hyun

    2014-06-01

    In situ Raman spectroscopy has been applied to analyze the surface oxide films formed on dissimilar metal weld (DMW) interfaces of nickel-base alloy/low alloy steel under hydrogenated high-temperature water condition. For the analysis of the oxide films under high temperature/pressure aqueous conditions, an in situ Raman spectroscopy system was developed by constructing a hydrothermal cell where the entire optics including the excitation laser and the Raman light collection system were located at the nearest position to the specimen by means of immersion optics. In situ Raman spectra of the DMW interfaces were collected in hydrogenated water condition at different temperatures up to 300 °C. The measured in situ Raman spectra showed peaks of Cr2O3, NiCr2O4 and Fe3O4 at the DMW interface. It is considered that differences in the oxide chemistry originated from the chemical element distribution inside of the DMW interface region.

  14. In Vitro Cytotoxicity of Calcium Silicate-Based Endodontic Cement as Root-End Filling Materials

    Directory of Open Access Journals (Sweden)

    Selen Küçükkaya

    2016-01-01

    Full Text Available The aim of this study was to evaluate the cytotoxicity of three types of calcium silicate-based endodontic cement after different incubation periods with human periodontal ligament fibroblasts. Human periodontal ligament fibroblasts were cultured from extracted third molars and seeded in 96-well plates. MTA, calcium enriched mixture (CEM cement, and Biodentine were prepared and added to culture insert plates which were immediately placed into 96-well plates containing cultured cells. After incubation periods of 24, 48, and 72 hours, cell viability was determined with WST-1 assay. Data were analysed statistically by ANOVA with repeated measures and Bonferroni tests. There was no significant difference in cell viability amongst the test materials after each incubation period (P>0.05. MTA and CEM presented more than 90% cell viability after 24 and 48 hours of incubation and showed statistically significant decrease in cell viability after 72 hours of incubation (P<0.05. Biodentine showed significantly less cell viability (73% after 24 hours of incubation, whereas more than 90% cell viability was seen after 48 and 72 hours of incubation (P<0.05. Despite the significant changes in cell viability over time, materials presented similar cytotoxicity profile. Biodentine and CEM can be considered as alternative materials for root-end surgery procedures.

  15. Chlorhexidine-calcium phosphate nanoparticles - Polymer mixer based wound healing cream and their applications.

    Science.gov (United States)

    Viswanathan, Kaliyaperumal; Monisha, P; Srinivasan, M; Swathi, D; Raman, M; Dhinakar Raj, G

    2016-10-01

    In this work, we developed a wound healing cream composed of two different polymers, namely chitosan and gelatin with chlorhexidine along with calcium phosphate nanoparticles. The physicochemical properties of the prepared cream were investigated based on SEM, EDX, Raman, FTIR and the results indicated that the cream contained gelatin, chitosan, calcium phosphate nanoparticles and chlorhexidine. The maximum swelling ratio studies indicated that the ratio was around of 52±2.2 at pH7.4 and the value was increased in acidic and alkaline pH. The antimicrobial activity was tested against bacteria and the results indicated that, both chlorhexidine and the hybrid cream devoid of chlorhexidine exhibited antimicrobial activity but the chlorhexidine impregnated cream showed three fold higher antimicrobial activity than without chlorhexidine. In vivo wound healing promoting activities of hybrid cream containing 0.4mg/L chlorhexidine were evaluated on surgically induced dermal wounds in mice. The results indicated that the cream with incorporated chlorhexidine significantly enhanced healing compared with the control samples. For the field validations, the veterinary clinical animals were treated with the cream and showed enhanced healing capacity. In conclusion, a simple and efficient method for design of a novel wound healing cream has been developed for veterinary applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Thermoluminescent properties of Dy doped calcium borate based glass for dose measurement subjected to photon irradiation

    Directory of Open Access Journals (Sweden)

    Tajuddin H. A.

    2017-01-01

    Full Text Available This study presents the thermoluminescent (TL dosimetric properties of calcium borate glass with various dopant concentration of dysprosium (Dy. Calcium borate glass is a new potential material to be used in radiation measurement with absorption coefficient that is close to human bone. A series of glasses based on chemical equation xCaO-(100-x B2O3 system, x = 0.1, 0.2, 0.3, 0.4, 0.5 (0< x <100 % weight have been prepared by melt quenching method. The X-ray diffraction analysis of glass samples were carried out and the result showed a broad peak, which confirmed the amorphous nature of the glass. The 70B2O3-30CaO glass sample was found as the most stable among other glass samples studied. Present work focuses on 70B2O3-30CaO glass of (0.01-0.4 mol% Dy-doped in order to investigate the thermoluminescence (TL properties, in particular, dose-response and fading. The glass samples were irradiated to dose range of 0.5-4.0 Gy subjected to 6MV photon irradiations of LINAC Primus MLC 3339. TL response of 0.3 mol% Dy-doped 70B2O3-30CaO glass was found to produce highest response, with good linear dose- response relationship.

  17. Chitosan-based hydrogel implants enriched with calcium ions intended for peripheral nervous tissue regeneration.

    Science.gov (United States)

    Nawrotek, Katarzyna; Tylman, Michał; Rudnicka, Karolina; Balcerzak, Jacek; Kamiński, Kamil

    2016-01-20

    A new method for fabrication of chitosan-based hydrogel implants intended for peripheral nervous tissue regeneration was developed. The method is based on an electrodeposition phenomenon from a solution of chitosan and organic acid. In order to increase the mechanical strength of the implant, the solution was enriched with hydroxyapatite. Hydroxyapatite served as a source of calcium ions too. The influence of the concentration of the polymer and the additive on chemical, mechanical as well as biological properties of the obtained implant was evaluated. The study showed great dependence of the initial solution composition mainly on the physicochemical properties of the resulting structure. Basic in vitro cytotoxic and pro-inflammatory assays showed biocompatibility of manufactured implants, therefore, animal experimentations may be considered. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Dosimetric studies of cadmium free alloy used in compensator based intensity modulated radiotherapy

    Science.gov (United States)

    Kaushik, Sandeep; Punia, Rajesh; Tyagi, Atul; Singh, Mann P.

    2017-10-01

    Aim of this study was to investigate dosimetric properties of cadmium free alloy which is used in compensator based intensity modulated radiotherapy (cIMRT). A mixture of lead, bismuth and tin was used to prepare the alloy whose melting point is 90-95 °C. Slabs of different thicknesses ranging from 0.71 cm to 6.14 cm were prepared. Density of alloy was measured by Archimedes' principle using water. For six megavolt (6 MV) photon beam energy transmission, linear effective attenuation coefficient (μeff), tissue phantom ratio (TPR1020), beam hardening, surface dose (Ds), percentage depth dose (PDD) and effect of scatter has been measured and analyzed for different field sizes and different thickness of compensator. Effect of extended source to detector distance (SDD) on transmissions and μeff was measured. The density of alloy was found to be 9.5456 g/cm3. At SDD of 100 cm, μeff was observed 0.4253 cm-1 for a field size of 10×10 cm 2. Calculated TPR1020 was found to be within 3% of experimental TPR1020 . It was found to be increasing with increasing thickness of compensator. Ds was found to decrease with thickness of compensator and increase with wider collimator opening due to increased scattered dose. Compensator slabs of 1 cm, 1.98 cm and 4.16 cm decreased surface dose by 4.2%, 6.1% and 9.5% respectively for a field size of 10×10 cm2 at 100 cm SDD. For small field size of 3×3 cm2 and 5×5 cm2 PDDs are increased from 3.0% to 5.5% of open beam PDDs as compensator thickness increased from 1 cm to 6.14 cm at a depth of 10 cm in water while variation in PDD is insignificant in for larger field sizes 10×10 cm2 to 20×20 cm2. A high degree of intensity modulation is essential in cIMRT and it can be achieved with this compensator material. Dosimetric properties analyzed in this study establish this alloy as a reliable, reusable, optimally dense and cost effective compensator material.

  19. The effect of processing techniques on microstructural and tribological properties of copper-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Vencl, Aleksandar, E-mail: avencl@mas.bg.ac.rs [Tribology Laboratory, Faculty of Mechanical Engineering, University of Belgrade, Kraljice Marije 16, 11120 Belgrade 35 (Serbia); Rajkovic, Viseslava, E-mail: visnja@vin.bg.ac.rs [Department of Materials Science, Institute of Nuclear Sciences “Vinca”, University of Belgrade, Mike Petrovića Alasa 12-14, 11001 Belgrade (Serbia); Zivic, Fatima, E-mail: zivic@kg.ac.rs [Tribology Center, Faculty of Engineering, University of Kragujevac, Sestre Janjić 6, 34000 Kragujevac (Serbia); Mitrović, Slobodan, E-mail: boban@kg.ac.rs [Tribology Center, Faculty of Engineering, University of Kragujevac, Sestre Janjić 6, 34000 Kragujevac (Serbia); Cvijović-Alagić, Ivana, E-mail: ivanac@vin.bg.ac.rs [Department of Materials Science, Institute of Nuclear Sciences “Vinca”, University of Belgrade, Mike Petrovića Alasa 12-14, 11001 Belgrade (Serbia); Jovanovic, Milan T., E-mail: miljov@vin.bg.ac.rs [Department of Materials Science, Institute of Nuclear Sciences “Vinca”, University of Belgrade, Mike Petrovića Alasa 12-14, 11001 Belgrade (Serbia)

    2013-09-01

    Three copper-based alloys, i.e. two composites reinforced with Al{sub 2}O{sub 3} particles and fabricated through PM route and Cu–Cr–Zr alloy processed by the vacuum melting and casting technique were the object of this investigation. Light microscope, scanning electron microscope (SEM) equipped with electron X-ray spectrometer (EDS) and transmission electron microscope (TEM) were used for microstructural characterization. The ball-on-disc nanotribometer served for wear and friction tests applying low sliding speeds (6, 8 and 10 mm/s) at constant load (1 N). The objective of the paper was to investigate the effect of different processing techniques on microstructure, thermal stability and the tribological characteristics of composites and copper ingot alloy. Nano-sized Al{sub 2}O{sub 3} particles (less than 100 nm in size) are present not only in the copper matrix of Cu–2.5 wt.% Al composite, obtained by internal oxidation, but they are also formed at the grain boundaries preventing the grain growth and providing very small grain size. During the high temperature annealing (in the range 300–950{sup o}C) composites behaved much better than the ingot alloy. The highest thermal stability showed Cu–2.5 wt.% Al composite. The pinning effect of nano-sized Al{sub 2}O{sub 3} particles prevents the grain growth slowing down recrystallization of this composite up to 900{sup o}C. Micro-sized Al{sub 2}O{sub 3} particles in Cu–5 wt.% Al{sub 2}O{sub 3} composite, processed by mechanical annealing, are not effective in preventing dislocation motion and the grain growth, whereas microstructure of Cu–0.4 wt.% Cr–0.08 wt.% Zr ingot alloy was completely recrystallized around 550{sup o}C. Cu–2.5 wt.% Al composite showed the best wear resistance, approximately 2.5 times higher than that of Cu–5 wt.% Al{sub 2}O{sub 3} composite. High hardness and nano-sized Al{sub 2}O{sub 3} particles size combined with the fine-grain structure are the main parameters leading to the

  20. Mineral Intake in Urban Pregnant Women from Base Diet, Fortified Foods, and Food Supplements: Focus on Calcium, Iron, and Zinc.

    Science.gov (United States)

    Jia, Hai Xian; Han, Jun Hua; Li, Hu Zhong; Liang, Dong; Deng, Tao Tao; Chang, Su Ying

    2016-12-01

    In the Chinese national nutrition surveys, fortified foods were not investigated separately from the base diet, and the contribution of fortified foods to micronutrients intake is not very clear. This study investigated the diet, including fortified foods and food supplements, of urban pregnant women and analyzed the intake of calcium, iron, and zinc to assess the corresponding contributions of fortified foods, food supplements, and the base diet. The results demonstrated that the base diet was the major source of calcium, iron, and zinc, and was recommended to be the first choice for micronutrients intake. Furthermore, consumption of fortified foods and food supplements offered effective approaches to improve the dietary intake of calcium, iron, and zinc in Chinese urban pregnant women. Copyright © 2016 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

  1. Fatigue Properties of Welded Butt Joint and Base Metal of MB8 Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    Ying-xia YU

    2016-09-01

    Full Text Available The fatigue properties of welded butt joint and base metal of MB8 magnesium alloy were investigated. The comparative fatigue tests were carried out using EHF-EM200K2-070-1A fatigue testing machine for both welded butt joint and base metal specimens with the same size and shape. The fatigue fractures were observed and analyzed by a scanning electron microscope of 6360 LA type. The experimental results show that the fatigue performance of the welded butt joint of MB8 magnesium alloy is sharply decreased. The conditional fatigue limit (1×107 of base metal and welded butt joint is about 69.41 and 32.76 MPa, respectively. The conditional fatigue limit (1×107 of the welded butt joint is 47.2 % of that of base metal. The main reasons are that the welding can lead to stress concentration in the weld toe area, tensile welding residual stress in the welded joint, as well as grain coarsening in the welding seam. The cleavage steps or quasi-cleavage patterns present on the fatigue fracture surface, indicating the fracture type of the welded butt joint belongs to a brittle fracture.DOI: http://dx.doi.org/10.5755/j01.ms.22.3.9132

  2. High-cycle Fatigue Properties of Alloy718 Base Metal and Electron Beam Welded Joint

    Science.gov (United States)

    Ono, Yoshinori; Yuri, Tetsumi; Nagashima, Nobuo; Sumiyoshi, Hideshi; Ogata, Toshio; Nagao, Naoki

    High-cycle fatigue properties of Alloy 718 plate and its electron beam (EB) welded joint were investigated at 293 K and 77 K under uniaxial loading. At 293 K, the high-cycle fatigue strength of the EB welded joint with the post heat treatment exhibited somewhat lower values than that of the base metal. The fatigue strengths of both samples basically increased at 77 K. However, in longer life region, the EB welded joint fractured from a blow hole formed in the welded zone, resulting in almost the same fatigue strength at 107 cycles as that at 293 K.

  3. The machinability of nickel-based alloys in high-pressure jet assisted (HPJA turning

    Directory of Open Access Journals (Sweden)

    D. Kramar

    2013-10-01

    Full Text Available Due to their mechanical, thermal and chemical properties, nickel-based alloys are generally included among materials that are hard to machine. An experimental study has been performed to investigate the capabilities of conventional and high-pressure jet assisted (HPJA turning of hard-to-machine materials, namely Inconel 718. The capabilities of different hard turning procedures are compared by means of chip breakability. The obtained results show that HPJA method offers a significant increase in chip breakability, under the same cutting conditions (cutting speed, feed rate, depth of cut.

  4. Transient liquid phase bonding of titanium-, iron- and nickel-based alloys

    Science.gov (United States)

    Rahman, A. H. M. Esfakur

    The operating temperature of land-based gas turbines and jet engines are ever-increasing to increase the efficiency, decrease the emissions and minimize the cost. Within the engines, complex-shaped parts experience extreme temperature, fatigue and corrosion conditions. Ti-based, Ni-based and Fe-based alloys are commonly used in gas turbines and jet engines depending on the temperatures of different sections. Although those alloys have superior mechanical, high temperature and corrosion properties, severe operating conditions cause fast degradation and failure of the components. Repair of these components could reduce lifecycle costs. Unfortunately, conventional fusion welding is not very attractive, because Ti reacts very easily with oxygen and nitrogen at high temperatures, Ni-based superalloys show heat affected zone (HAZ) cracking, and stainless steels show intergranular corrosion and knife-line attack. On the other hand, transient liquid phase (TLP) bonding method has been considered as preferred joining method for those types of alloys. During the initial phase of the current work commercially pure Ti, Fe and Ni were diffusion bonded using commercially available interlayer materials. Commercially pure Ti (Ti-grade 2) has been diffusion bonded using silver and copper interlayers and without any interlayer. With a silver (Ag) interlayer, different intermetallics (AgTi, AgTi2) appeared in the joint centerline microstructure. While with a Cu interlayer eutectic mixtures and Ti-Cu solid solutions appeared in the joint centerline. The maximum tensile strengths achieved were 160 MPa, 502 MPa, and 382 MPa when Ag, Cu and no interlayers were used, respectively. Commercially pure Fe (cp-Fe) was diffusion bonded using Cu (25 m) and Au-12Ge eutectic interlayer (100 microm). Cu diffused predominantly along austenite grain boundaries in all bonding conditions. Residual interlayers appeared at lower bonding temperature and time, however, voids were observed in the joint

  5. Modeling-Based Processing of Al-Li Alloys for Delamination Resistance Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Al-Li alloys are of interest for use in aerospace structures due to the desirable combination of high strength and low density. However, high strength Al-Li alloys...

  6. Corrosion behaviour of austenitic stainless steel, nickel-base alloy and its weldments in aqueous LiBr solutions

    Energy Technology Data Exchange (ETDEWEB)

    Blasco-Tamarit, E.; Igual-Munoz, A.; Garcia Anton, J.; Garcia-Garcia, D. [Departamento de Ingenieria Quimica y Nuclear. E.T.S.I.Industriales, Universidad Politecnica de Valencia, P.O. Box 22012 E-46071 Valencia (Spain)

    2004-07-01

    With the advances in materials production new alloys have been developed, such as High- Alloy Austenitic Stainless Steels and Nickel-base alloys, with high corrosion resistance. These new alloys are finding applications in Lithium Bromide absorption refrigeration systems, because LiBr is a corrosive medium which can cause serious corrosion problems, in spite of its favourable properties as absorbent. The objective of the present work was to study the corrosion resistance of a highly alloyed austenitic stainless steel (UNS N08031) used as base metal, a Nickel-base alloy (UNS N06059) used as its corresponding filler metal, and the weld metal obtained by the Gas Tungsten Arc Welding (GTAW) procedure. The materials have been tested in different LiBr solutions (400 g/l, 700 g/l, 850 g/l and a commercial 850 g/l LiBr heavy brine containing Lithium Chromate as corrosion inhibitor), at 25 deg. C. Open Circuit Potential tests and potentiodynamic anodic polarization curves have been carried out to obtain information about the general electrochemical behaviour of the materials. The polarization curves of all the alloys tested were typical of passivable materials. Pitting corrosion susceptibility has been evaluated by means of cyclic potentiodynamic curves, which provide parameters to analyse re-passivation properties. The galvanic corrosion generated by the electrical contact between the welded and the base material has been estimated from the polarization diagrams according to the Mixed Potential Method. Samples have been etched to study the microstructure by Scanning Electron Microscopy (SEM). The results demonstrate that the pitting resistance of all these materials increases as the LiBr concentration decreases. In general, the presence of chromate tended to shift the pitting potential to more positive values than those obtained in the 850 g/l LiBr solution. (authors)

  7. Temperature-dependent rigidity and magnetism of polyamide 6 nanocomposites based on nanocrystalline Fe-Ni alloy of various geometries

    Directory of Open Access Journals (Sweden)

    M. A. A. Mohamed

    2016-10-01

    Full Text Available The focus of this study is to explore the potential use of Polyamide 6 nanocomposite reinforced with nanocrystalline (nc Fe20Ni80 alloy (Fe20Ni80/PA6 PNC in electromagnetic applications and provide understanding of how the alloy particle geometry is controlling the nanocomposite’s physical properties. Thermomechanical rigidity, room-temperature soft magnetic performance and thermal soft magnetic stability of Fe20Ni80/PA6 PNCs based on spherical-sea urchin alloy particles (UMB2-SU and necklace-like alloy chains (UMB2-NC have been investigated. Both PNCs have considerably superior bulk properties compared to neat PA6 and UMB2-SU exhibits the most remarkable overall performance. Morphological observations disclose two relevant phenomena: i improved dispersion and distribution of the SU alloy particles than the NC ones within PA6 matrix, leading to stronger filler-matrix interfacial interactions within the UMB2-SU as compared to the UMB2-NC and ii presence of constraint polymer regions in between alloy segments within the UMB2-SU that provide secondary reinforcing and soft magnetic mechanisms. Such phenomena along with the lower alloy crystallite size and PA6 γ-crystal type content within the UMB2-SU than in the UMB2-NC, are considered the main responsible factors for the distinctive performance of UMB2-SU. Overall, compared to various ferromagnetic nanocrystalline metallic materials, the research proposes the SU nc Fe20Ni80 alloy as a valuable nanofiller in polymers for electromagnetic applications.

  8. The dissimilar brazing of Kovar alloy to SiCp/Al composites using silver-based filler metal foil

    Science.gov (United States)

    Wang, Peng; Xu, Dongxia; Zhai, Yahong; Niu, Jitai

    2017-09-01

    Aluminum metal matrix composites with high SiC content (60 vol.% SiCp/Al MMCs) were surface metallized with a Ni-P alloy coating, and vacuum brazing between the composites and Kovar alloy were performed using rapidly cooled Ag-22.0Cu-15.9In-10.86Sn-1.84Ti (wt%) foil. The effects of Ni-P alloy coating and brazing parameters on the joint microstructures and properties were researched by SEM, EDS, and single lap shear test, respectively. Results show that Ag-Al intermetallic strips were formed in the 6063Al matrix and filler metal layer because of diffusion, and they were arranged regularly and accumulated gradually as the brazing temperature was increased ( T/°C = 550-600) or the soaking time was prolonged ( t/min = 10-50). However, excessive strips would destroy the uniformity of seams and lead to a reduced bonding strength (at most 70 MPa). Using a Ni-P alloy coating, void free joints without those strips were obtained at 560 °C after 20 min soaking time, and a higher shear strength of 90 MPa was achieved. The appropriate interface reaction ( 2 μm transition layer) that occurred along the Ni-P alloy coating/filler metal/Kovar alloy interfaces resulted in better metallurgical bonding. In this research, the developed Ag-based filler metal was suitable for brazing the dissimilar materials of Ni-P alloy-coated SiCp/Al MMCs and Kovar alloy, and capable welding parameters were also broadened.

  9. Impact behaviors of poly-lactic acid based biocomposite reinforced with unidirectional high-strength magnesium alloy wires

    Directory of Open Access Journals (Sweden)

    Xuan Li

    2014-10-01

    Full Text Available A novel poly-lactic acid (PLA based biocomposite reinforced with unidirectional high-strength magnesium alloy (Mg-alloy wires for bone fracture fixation was fabricated by hot-compressing process. The macroscopical and microscopical impact behaviors of the biocomposite were investigated using impact experiments and finite element method (FEM, respectively. The results indicated that the biocomposite had favorable impact properties due to the plastic deformation behavior of Mg-alloy wires during impact process. While the content of Mg-alloy wires reached 20 vol%, the impact strength of the composite could achieve 93.4 kJ/m2, which is approximate 16 times larger than that of pure PLA fabricated by the same process. According to FEM simulation results, the complete destruction life of the composites during impact process increased with increasing volume fraction of Mg-alloy wires, indicating a high impact-bearing ability of the composite for bone fracture fixation. Simultaneously, the energy absorbed by Mg-alloy wires in the composites had a corresponding increase. In addition, it denoted that the impact properties of the composites are sensitive to the initial properties of the matrix material.

  10. Static and dynamic cyclic oxidation of 12 nickel-, cobalt-, and iron-base high-temperature alloys

    Science.gov (United States)

    Barrett, C. A.; Johnston, J. R.; Sanders, W. A.

    1978-01-01

    Twelve typical high-temperature nickel-, cobalt-, and iron-base alloys were tested by 1 hr cyclic exposures at 1038, 1093, and 1149 C and 0.05 hr exposures at 1093 C. The alloys were tested in both a dynamic burner rig at Mach 0.3 gas flow and in static air furnace for times up to 100 hr. The alloys were evaluated in terms of specific weight loss as a function of time, and X-ray diffraction analysis and metallographic examination of the posttest specimens. A method previously developed was used to estimate specific metal weight loss from the specific weight change of the sample. The alloys were then ranked on this basis. The burner-rig test was more severe than a comparable furnace test and resulted in an increased tendency for oxide spalling due to volatility of Cr in the protective scale and the more drastic cooling due to the air-blast quench of the samples. Increased cycle frequency also increased the tendency to spall for a given test exposure. The behavior of the alloys in both types of tests was related to their composition and their tendency to form scales. The alloys with the best overall behavior formed alpha-Al2O3 aluminate spinels.

  11. Microstructures and Mechanical Properties of Co-Cr Dental Alloys Fabricated by Three CAD/CAM-Based Processing Techniques

    Directory of Open Access Journals (Sweden)

    Hae Ri Kim

    2016-07-01

    Full Text Available The microstructures and mechanical properties of cobalt-chromium (Co-Cr alloys produced by three CAD/CAM-based processing techniques were investigated in comparison with those produced by the traditional casting technique. Four groups of disc- (microstructures or dumbbell- (mechanical properties specimens made of Co-Cr alloys were prepared using casting (CS, milling (ML, selective laser melting (SLM, and milling/post-sintering (ML/PS. For each technique, the corresponding commercial alloy material was used. The microstructures of the specimens were evaluated via X-ray diffractometry, optical and scanning electron microscopy with energy-dispersive X-ray spectroscopy, and electron backscattered diffraction pattern analysis. The mechanical properties were evaluated using a tensile test according to ISO 22674 (n = 6. The microstructure of the alloys was strongly influenced by the manufacturing processes. Overall, the SLM group showed superior mechanical properties, the ML/PS group being nearly comparable. The mechanical properties of the ML group were inferior to those of the CS group. The microstructures and mechanical properties of Co-Cr alloys were greatly dependent on the manufacturing technique as well as the chemical composition. The SLM and ML/PS techniques may be considered promising alternatives to the Co-Cr alloy casting process.

  12. Processing and characterization of amorphous magnesium based alloy for application in biomedical implants

    Directory of Open Access Journals (Sweden)

    Telma Blanco Matias

    2014-07-01

    Full Text Available Magnesium-based bulk metallic glasses are attractive due to their single-phase, chemically homogeneous alloy system and the absence of second-phase, which could impair the mechanical properties and corrosion resistance. However, one of the unsolved problems for the manufacturability and the applications of bulk metallic glasses is that their glass-forming ability is very sensitive to the preparation techniques and impurity of components since oxygen in the environment would markedly deteriorate the glass-forming ability. Therefore, the aim of this study was to establish proper processing conditions to obtain a magnesium-based amorphous ternary alloy and its characterization. The final composition was prepared using two binary master alloys by melting in an induction furnace. Carbon steel crucible was used in argon atmosphere with and without addition of SF6 gas in order to minimize the oxygen contamination. The microstructure, amorphous nature, thermal properties and chemical analysis of samples were investigated by scanning electron microscopy (SEM, X-ray diffraction (XRD, differential scanning calorimetry (DSC and inductively coupled plasma emission spectrometry, respectively. The oxygen content of the as-cast samples was chemically analyzed by using carrier gas hot extraction (O/N Analyzer TC-436/LECO and was kept bellow 25 ppm (without SF6 and 10 ppm (with SF6. Bulk samples were produced by rapid cooling in a cooper mold until 1.5 mm thickness, with amorphous structures being observed up to 2.5 mm.

  13. Impact of dilution on the microstructure and properties of Ni-based 625 alloy coatings

    Directory of Open Access Journals (Sweden)

    Tiago Jose Antoszczyszyn

    2014-06-01

    Full Text Available Nickel-based alloy IN 625 is used to protect components of aircrafts, power generation and oil refinery due to an association of toughness and high corrosion resistance. These properties are associated with the chemical composition and microstructure of coatings which depend on the processing parameters and the composition of the component being protected. This paper assessed impact of dilution on the microstructure and properties of the Ni alloy IN 625 deposited by Plasma Transferred Arc (PTA on two substrates: carbon steel API 5L and stainless steel AISI 316L. Differences due to the interaction with the substrate were maximized analyzing single layer coatings, processed with three deposition current: 120, 150 and 180 A. Correlation with a cast Nickel-based alloy sample contributed to assess the impact of dilution on coatings. Dilution was determined by the area ratio and Vickers hardness measured on the transverse section of coatings. Scanning electron and Laser confocal microscopy and X-ray diffraction analysis were carried out to characterize the microstructure. Results indicated the increasing dilution with the deposition current was deeply influenced by the substrate. Dilution ranging from 5 to 29% was measured on coatings processed on the API 5L steel and from 22 to 51% on the low thermal conductivity AISI 316L steel substrate. Differences on the microstructure and properties of coatings can be associated with the interaction with each substrate. Higher fraction of carbides account for the higher coating hardness when processing on API 5L whereas the low thermal conductivity of AISI 316L and the higher Fe content in solid solution contributed to the lower hardness of coatings.

  14. Comparison of brazed joints made with BNi-1 and BNi-7 nickel-base brazing alloys

    Directory of Open Access Journals (Sweden)

    Zorc, Borut

    2000-04-01

    Full Text Available Kinetics of the processes are different with different types of brazing alloys. Precipitation processes in the parent metal close to the brazing gap are of great importance. They control the mechanical properties of the joint area when the brittle eutectic has disappeared from the gap. A comparative study of brazed joints on austenitic stainless alloys made with BNi-7 (Ni-P type and BNi-1 (Ni-Si-B type brazing alloys was made. Brazing alloys containing phosphorus behave in a different manner to those containing boron.

    Las aleaciones de níquel se producen mediante tres sistemas de aleación: Ni-P, Ni-Si y Ni-B. Durante las reacciones metalúrgicas con el metal de base, la eutéctica frágil en la separación soldada puede transformarse en la solución dúctil-sólida con todas aleaciones. La cinética del proceso varía según el tipo de aleación. Los procesos de precipitación en el metal de base cerca de la separación soldada son de mucha importancia, ya que controlan las propiedades mecánicas de la área de unión después de desaparecer la eutéctica frágil de la separación. Se ha hecho un análisis comparativo de uniones soldadas en aleaciones austeníticas inoxidables realizadas con aleaciones BNi-7 (tipo Ni-P y BNi-1 (tipo Ni-Si-B. Las aleaciones que contienen fósforo se comportan de una manera diferente, tanto con el cambio de la eutéctica a la solución sólida, como con los procesos de precipitación en el metal de base cerca de la unión soldada.

  15. Development of improved low-strain creep strength in Cabot alloy R-41 sheet. [nickel base sheet alloy for reentry shielding

    Science.gov (United States)

    Rothman, M. F.

    1984-01-01

    The feasibility of improving the low-strain creep properties of a thin gauge nickel base sheet alloy through modified heat treatment or through development of a preferred crystal-lographic texture was investigated. The basic approach taken to improve the creep strength of the material by heat treatment was to increase grain size by raising the solution treatment temperature for the alloy to the range of 1420 K to 1475 K (2100 F to 2200 F). The key technical issue involved was maintenance of adequate tensile ductility following the solutioning of M6C primary carbides during the higher temperature solution treatment. The approach to improve creep properties by developing a sheet texture involved varying both annealing temperatures and the amount of prior cold work. Results identified a heat treatment for alloy R-14 sheet which yields a substantial creep-life advantage at temperatures above 1090 K (1500 F) when compared with material given the standard heat treatment. At the same time, this treatment provides reasonable tensile ductility over the entire temperature range of interest. The mechanical properties of the material given the new heat treatment are compared with those for material given the standard heat treatment. Attempts to improve creep strength by developing a sheet texture were unsuccessful.

  16. Chromium and iron contained half-Heusler MnNiGe-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Budzynski, M. [UMCS, Institute of Physics, 1 sq.M.Curie-Skłodowska, 20-031 Lublin (Poland); Valkov, V.I.; Golovchan, A.V.; Kamenev, V.I. [Donetsk Institute for Physics and Engineering, 72, R.Luxemburg str., 83114 Donetsk (Ukraine); Mitsiuk, V.I., E-mail: vmitsiuk@gmail.com [Scientific-Practical Materials Research Center of National Academy of Sciences of Belarus, 19 P.Brovky Str., 220072 Minsk (Belarus); Sivachenko, A.P. [Donetsk Institute for Physics and Engineering, 72, R.Luxemburg str., 83114 Donetsk (Ukraine); Surowiec, Z. [UMCS, Institute of Physics, 1 sq.M.Curie-Skłodowska, 20-031 Lublin (Poland); Tkachenka, T.M. [Scientific-Practical Materials Research Center of National Academy of Sciences of Belarus, 19 P.Brovky Str., 220072 Minsk (Belarus)

    2015-12-15

    The magnetic characteristics of chromium and iron containing MnNiGe-based alloys with several types of quenching and annealing were investigated. It was found that the quenched Mn{sub 0.89}Cr{sub 0.11}NiGe has a spontaneous and magnetic field induced magnetostructural first-order transitions at room temperature. These transitions might be accompanied by a large magnetocaloric effect. In general, Mn{sub 0.89}Cr{sub 0.11}NiGe can be classified as promising material for use in the magnetocaloric application at room temperatures. The first order magnetostructural phase transition from the ferromagnetic to paramagnetic state is not realized in MnNi0.90Fe0.10Ge. In contrast to Mn{sub 0.89}Cr{sub 0.11}NiGe, however, the FM state in quenched-on-wheel MnNi0.90Fe0.10Ge is preserved to the lowest temperatures. Based on the set of the magnetic properties, it has been concluded that the iron containing MnNiGe-based alloys are less promising for practical use.

  17. Mechanism-based modeling of solute strengthening: application to thermal creep in Zr alloy

    Energy Technology Data Exchange (ETDEWEB)

    Tome, Carlos [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Wen, Wei [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Capolungo, Laurent [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-08-01

    This report focuses on the development of a physics-based thermal creep model aiming to predict the behavior of Zr alloy under reactor accident condition. The current models used for this kind of simulations are mostly empirical in nature, based generally on fits to the experimental steady-state creep rates under different temperature and stress conditions, which has the following limitations. First, reactor accident conditions, such as RIA and LOCA, usually take place in short times and involve only the primary, not the steady-state creep behavior stage. Moreover, the empirical models cannot cover the conditions from normal operation to accident environments. For example, Kombaiah and Murty [1,2] recently reported a transition between the low (n~4) and high (n~9) power law creep regimes in Zr alloys depending on the applied stress. Capturing such a behavior requires an accurate description of the mechanisms involved in the process. Therefore, a mechanism-based model that accounts for the evolution with time of microstructure is more appropriate and reliable for this kind of simulation.

  18. Comparison of Shear Bond Strengths of three resin systems for a Base Metal Alloy bonded to

    Directory of Open Access Journals (Sweden)

    Jlali H

    1999-12-01

    Full Text Available Resin-bonded fixed partial dentures (F.P.D can be used for conservative treatment of partially edentulous"npatients. There are numerous studies regarding the strength of resin composite bond to base meta! alloys. Shear bond"nstrength of three resin systems were invistigated. In this study these systems consisted of: Panavia Ex, Mirage FLC and"nMarathon V. Thirty base metal specimens were prepared from rexillium III alloy and divided into three groups. Then each"ngroup was bonded to enamel of human extracted molar teeth with these systems. All of specimens were stored in water at"n37ac for 48 hours. A shear force was applied to each specimen by the instron universal testing machine. A statistical"nevaluation of the data using one-way analysis of variance showed that there was highly significant difference (P<0.01"nbetween the bond strengths of these three groups."nThe base metal specimens bonded with panavia Ex luting agent, exhibited the highest mean bond strength. Shear bond"nstrength of the specimens bonded to enamel with Mirage F1C showed lower bond strenght than panavia EX. However, the"nlowest bond strength was obtained by the specimens bonded with Marathon V.

  19. Synthesis of Fe–Si–B–Mn-based nanocrystalline magnetic alloys ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Alloys of Fe–Si–B with varying compositions of Mn were prepared using high energy planetary ball mill for maximum duration of 120 h. ... power electrical industry, where these alloys are used in transformers, chokes, filters, etc .... which indicate more dissolution of the alloying elements with increased milling time.

  20. Calcium Carbonate

    Science.gov (United States)

    Calcium carbonate is a dietary supplement used when the amount of calcium taken in the diet is not ... for healthy bones, muscles, nervous system, and heart. Calcium carbonate also is used as an antacid to relieve ...

  1. Calcium supplements

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/007477.htm Calcium supplements To use the sharing features on this page, please enable JavaScript. WHO SHOULD TAKE CALCIUM SUPPLEMENTS? Calcium is an important mineral for the ...

  2. 3D printing of mineral-polymer bone substitutes based on sodium alginate and calcium phosphate.

    Science.gov (United States)

    Egorov, Aleksey A; Fedotov, Alexander Yu; Mironov, Anton V; Komlev, Vladimir S; Popov, Vladimir K; Zobkov, Yury V

    2016-01-01

    We demonstrate a relatively simple route for three-dimensional (3D) printing of complex-shaped biocompatible structures based on sodium alginate and calcium phosphate (CP) for bone tissue engineering. The fabrication of 3D composite structures was performed through the synthesis of inorganic particles within a biopolymer macromolecular network during 3D printing process. The formation of a new CP phase was studied through X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. Both the phase composition and the diameter of the CP particles depend on the concentration of a liquid component (i.e., the "ink"). The 3D printed structures were fabricated and found to have large interconnected porous systems (mean diameter ≈800 μm) and were found to possess compressive strengths from 0.45 to 1.0 MPa. This new approach can be effectively applied for fabrication of biocompatible scaffolds for bone tissue engineering constructions.

  3. A chemical activity evaluation of two dental calcium silicate-based materials

    Directory of Open Access Journals (Sweden)

    Chalas Renata

    2015-06-01

    Full Text Available Calcium silicate-based materials are interesting products widely used in dentistry. The study was designed to compare the chemical reaction between analyzed two preparates and dentin during cavity lining. In our work, dentinal discs were prepared from human extracted teeth filled with Biodentine and MTA+. The samples were then analyzed by way of SEM, EDS and Raman spectroscopy. The obtained results revealed differences in elemental composition between both materials. Biodentine showed higher activity in contact with dentine. Moreover, the interfacial layer in the tooth filled by Biodentine was wider than that in the tooth filled with MTA+. The applied methods of analysis confirmed that both materials have a bioactive potential which is a promising ability.

  4. Induction and consolidation of calcium-based homo- and heterosynaptic potentiation and depression

    DEFF Research Database (Denmark)

    Li, Y; Kulvicius, T.; Tetzlaff, Christian

    2016-01-01

    -lasting late-phase state. The underlying processes of this synaptic consolidation are already well-known for homosynaptic plasticity, however, it is not clear whether the same processes also enable the induction and consolidation of heterosynaptic plasticity. In this study, by extending a generic calcium......-based plasticity model with the processes of synaptic consolidation, we show in simulations that indeed heterosynaptic plasticity can be induced and, furthermore, consolidated by the same underlying processes as for homosynaptic plasticity. Furthermore, we show that by local diffusion processes the heterosynaptic......The adaptive mechanisms of homo- and heterosynaptic plasticity play an important role in learning and memory. In order to maintain plasticity-induced changes for longer time scales (up to several days), they have to be consolidated by transferring them from a short-lasting early-phase to a long...

  5. Light Hydrocarbons Adsorption Mechanisms in Two Calcium-based Microporous Metal Organic Frameworks

    KAUST Repository

    Plonka, Anna M.

    2016-01-25

    The adsorption mechanism of ethane, ethylene and acetylene (C2Hn; n=2, 4, 6) on two microporous metal organic frameworks (MOFs) is described here that is consistent with observations from single crystal and powder X-ray diffraction, calorimetric measurments and gas adsorption isotherm measurements. Two calcium-based MOFs, designated as SBMOF-1 and SBMOF-2 (SB: Stony Brook), form three-dimensional frameworks with one-dimensional open channels. As determined form single crystal diffraction experiments channel geometries of both SBMOF-1 and SBMOF-2 provide multiple adsorption sites for hydrocarbon molecules trough C-H…π and C-H…O interactions, similarly to interactions in the molecular and protein crystals. Both materials selectively adsorb C2 hydrocarbon gases over methane as determined with IAST and breakthrough calculations, with C2H6/CH4 selectivity as high as 74 in SBMOF-1.

  6. Intrusion features of a high-speed striker of a porous tungsten-based alloy with a strengthening filler in a steel barrier

    Science.gov (United States)

    Ishchenko, A. N.; Afanas'eva, S. A.; Belov, N. N.; Burkin, V. V.; Rogaev, K. S.; Sammel', A. Yu.; Skosyrskii, A. B.; Tabachenko, A. N.; Yugov, N. T.

    2017-09-01

    The complex problem of increasing the penetrating power of strikers based on highly porous tungsten composites is considered by improving their strengthening properties by alloying the hardening components under high-speed collision conditions. Using the method of liquid-phase sintering, we fabricated samples of strikers based on a porous WNiFeCo alloy (tungsten + nickel + iron + cobalt), alloyed with tungsten carbide with cobalt (WCCo8) and titanium-tungsten carbide (TiWC). Dynamic tests of the strikers from the developed alloys were carried out at the collision velocity with a steel barrier of the order of 2800 m/s. The penetration depth of the striker based on a porous WNiFeCo alloy doped with tungsten carbides is 30% higher than the penetration depth of a striker of a monolithic WNiFe-90 alloy (tungsten + nickel + iron with a tungsten content of 90%).

  7. Long-term creep rupture strength of weldment of Fe-Ni based alloy as candidate tube and pipe for advanced USC boilers

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Gang; Sato, Takashi [Babcok-Hitachi K.K., Hiroshima (Japan). Kure Research Laboratory; Marumoto, Yoshihide [Babcok-Hitachi K.K., Hiroshima (Japan). Kure Div.

    2010-07-01

    A lot of works have been going to develop 700C USC power plant in Europe and Japan. High strength Ni based alloys such as Alloy 617, Alloy 740 and Alloy 263 were the candidates for boiler tube and pipe in Europe, and Fe-Ni based alloy HR6W (45Ni-24Fe-23Cr-7W-Ti) is also a candidate for tube and pipe in Japan. One of the Key issues to achieve 700 C boilers is the welding process of these alloys. Authors investigated the weldability and the long-term creep rupture strength of HR6W tube. The weldments were investigated metallurgically to find proper welding procedure and creep rupture tests are ongoing exceed 38,000 hours. The long-term creep rupture strengths of the HST weld joints are similar to those of parent metals and integrity of the weldments was confirmed based on with other mechanical testing results. (orig.)

  8. Comparative evaluation of calcium silicate-based dentin substitute (Biodentine?) and calcium hydroxide (pulpdent) in the formation of reactive dentin bridge in regenerative pulpotomy of vital primary teeth: Triple blind, randomized clinical trial

    OpenAIRE

    Navneet Grewal; Rubica Salhan; Nirapjeet Kaur; Hemal Bipin Patel

    2016-01-01

    Background: Considering the biological concerns of calcium hydroxide (CH) as a pulpotomy agent, an alternative silicate based dentin substitute i.e. Biodentine (Ca3SiO5) was evaluated clinically and radiographically. Aims: To evaluate the effectiveness of dentin substitute (Biodentine) in regenerative pulpotomy of vital primary teeth that would giv a biological base to its use in forming reactive dentin bridge and overcoming the drawbacks of calcium hydroxide. Material and Methods: Randomised...

  9. Osteogenic and Angiogenic Response to Calcium Silicate-based Endodontic Sealers.

    Science.gov (United States)

    Costa, Fábio; Sousa Gomes, Pedro; Fernandes, Maria Helena

    2016-01-01

    Calcium silicate-based endodontic sealers are reported to favor the regeneration of periradicular tissues, a process requiring concerted osteogenic and angiogenic events. This study compared 4 calcium silicate-based sealers for the effects of their extracts on osteogenic and angiogenic cell behavior. Extracts from ProRoot MTA (Dentsply Tulsa Dental, Tulsa, OK), MTA Plus (Prevest Denpro Limited, Jammu City, India), MTA Fillapex (Angelus, Londrina, PR, Brazil), and Biodentine (Septodont, Saint-Maur-des-Fosses, France) were prepared from freshly mixed sealers (0.1 g/cm(2)/mL extraction medium) and diluted (1:2-1:20). The sealers were compared for the dose- and time-dependent effects on the proliferation and differentiation of human mesenchymal stem cells (hMSCs) and human umbilical vein endothelial cells (HUVECs). An ex vivo osteogenic assay (regeneration of neonatal mice parietal bone defects) and an in vivo angiogenesis assay (chorioallantoic membrane assay) were performed. Diluted extracts from MTA ProRoot and MTA Plus had evident stimulatory effects on the proliferation of hMSCs, alkaline phosphatase activity, and ex vivo regeneration of bone defects. They also increased HUVEC growth; allowed normal tubularlike network organization; and, in vivo, did not affect angiogenesis. Comparatively, Biodentine also elicited a favorable response on hMSCs and HUVECs, but the overall osteogenic and angiogenic outcome was slightly lower. MTA Fillapex exhibited the highest toxicity in hMSCs and HUVECs and, unlike the other sealers, only allowed a partial regeneration of bone defects. The sealers caused dose- and time-dependent effects on the osteoblastic and endothelial response, eliciting similar cytocompatibility profiles. Results suggest that the induction of both osteogenic and angiogenic events may contribute to the sealers' regenerative outcome. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  10. Structure-Composition-Property Relationships in Polymeric Amorphous Calcium Phosphate-Based Dental Composites

    Directory of Open Access Journals (Sweden)

    Drago Skrtic

    2009-11-01

    Full Text Available Our studies of amorphous calcium phosphate (ACP-based materials over the last decade have yielded bioactive polymeric composites capable of protecting teeth from demineralization or even regenerating lost tooth mineral. The anti-cariogenic/remineralizing potential of these ACP composites originates from their propensity, when exposed to the oral environment, to release in a sustained manner sufficient levels of mineral-forming calcium and phosphate ions to promote formation of stable apatitic tooth mineral. However, the less than optimal ACP filler/resin matrix cohesion, excessive polymerization shrinkage and water sorption of these experimental materials can adversely affect their physicochemical and mechanical properties, and, ultimately, limit their lifespan. This study demonstrates the effects of chemical structure and composition of the methacrylate monomers used to form the matrix phase of composites on degree of vinyl conversion (DVC and water sorption of both copolymers and composites and the release of mineral ions from the composites. Modification of ACP surface via introducing cations and/or polymers ab initio during filler synthesis failed to yield mechanically improved composites. However, moderate improvement in composite’s mechanical stability without compromising its remineralization potential was achieved by silanization and/or milling of ACP filler. Using ethoxylated bisphenol A dimethacrylate or urethane dimethacrylate as base monomers and adding moderate amounts of hydrophilic 2-hydroxyethyl methacrylate or its isomer ethyl-α-hydroxymethacrylate appears to be a promising route to maximize the remineralizing ability of the filler while maintaining high DVC. Exploration of the structure/composition/property relationships of ACP fillers and polymer matrices is complex but essential for achieving a better understanding of the fundamental mechanisms that govern dissolution/re-precipitation of bioactive ACP fillers, and

  11. Wear Characteristics of Hybrid Composites Based on Za27 Alloy Reinforced With Silicon Carbide and Graphite Particles

    Directory of Open Access Journals (Sweden)

    S. Mitrović

    2014-06-01

    Full Text Available The paper presents the wear characteristics of a hybrid composite based on zinc-aluminium ZA27 alloy, reinforced with silicon-carbide and graphite particles. The tested sample contains 5 vol.% of SiC and 3 vol.% Gr particles. Compocasting technique has been used to prepare the samples. The experiments were performed on a “block-on-disc” tribometer under conditions of dry sliding. The wear volumes of the alloy and the composite were determined by varying the normal loads and sliding speeds. The paper contains the procedure for preparation of sample composites and microstructure of the composite material and the base ZA27 alloy. The wear surface of the composite material was examined using the scanning electronic microscope (SEM and energy dispersive spectrometry (EDS. Conclusions were obtained based on the observed impact of the sliding speed, normal load and sliding distance on tribological behaviour of the observed composite.

  12. Partially and fully de-alloyed glassy ribbons based on Au: Application in methanol electro-oxidation studies

    Energy Technology Data Exchange (ETDEWEB)

    Paschalidou, Eirini Maria, E-mail: epaschal@unito.it [Dipartimento di Chimica e Centro Interdipartimentale NIS (Nanostructured Surfaces and Interfaces), Università di Torino, Via Pietro Giuria 7, 10125, Torino (Italy); Scaglione, Federico [Dipartimento di Chimica e Centro Interdipartimentale NIS (Nanostructured Surfaces and Interfaces), Università di Torino, Via Pietro Giuria 7, 10125, Torino (Italy); Gebert, Annett; Oswald, Steffen [Leibniz Institut für Festkörper- und Werkstoffforschung IFW, Helmholtzstraße 20, 01069, Dresden (Germany); Rizzi, Paola; Battezzati, Livio [Dipartimento di Chimica e Centro Interdipartimentale NIS (Nanostructured Surfaces and Interfaces), Università di Torino, Via Pietro Giuria 7, 10125, Torino (Italy)

    2016-05-15

    In this work, electrochemical de-alloying of an amorphous alloy, Au{sub 40}Cu{sub 28}Ag{sub 7}Pd{sub 5}Si{sub 20}, cast in ribbon form by melt spinning, has been performed, obtaining self standing nanoporous materials suitable for use as electrodes for electrocatalytic applications. The de-alloying encompasses removal of less noble elements and the crystallization of Au, resulting in interconnected ligaments whose size and morphology are described as a function of time. Depending on de-alloying time, the crystals may contain residual amounts of Cu, Ag and Pd, as shown by Auger Electron Spectroscopy (AES), Energy Dispersive Spectroscopy (EDS) and Cyclic Voltammetry (CV) in a basic solution. Current density peaks in the 0.16–0.28 V range (vs Ag/AgCl) indicate that the porous ribbons are active for the electro-oxidation of methanol. The partially de-alloyed samples, which still partially contain the amorphous phase because of the shorter etching times, have finer ligaments and display peaks at lower potential. However, the current density decreases rapidly during repeated potential scans. This is attributed to the obstruction of Au sites, mainly by the Cu oxides formed during the scans. The fully de-alloyed ribbons display current peaks at about 0.20 V and remain active for hundreds of scans at more than 60% of the initial current density. They can be fully re-activated to achieve the same performance levels after a brief immersion in nitric acid. The good activity is due to trapped Ag and Pd atoms in combination with ligament morphology. - Graphical abstract: Fine ligaments and pores made by de-alloying a glassy ribbon of a Au-based alloy, homogeneously produced across the thickness (25 μm) for studying methanol's electro-oxidation behavior. - Highlights: • Size and composition of nanoporous layers tailored in de-alloying Au-based glassy ribbons. • From amorphous precursor fine crystals occur in ligaments with residual Pd and Ag. • Fully de-alloyed

  13. [Comparison of the clinical effects of selective laser melting deposition basal crowns and cobalt chromium alloy base crowns].

    Science.gov (United States)

    Li, Jing-min; Wang, Wei-qian; Ma, Jing-yuan

    2014-06-01

    To evaluate the clinical effects of selective laser melting (SLM) deposition basal crowns and cobalt chromium alloy casting base crowns. One hundred and sixty eight patients treated with either SLM deposition basal crowns (110 teeth) or cobalt chromium alloy casting basal crowns (110 teeth) were followed-up for 1 month, 6 months, 12 months and 24 months. The revised standard of American Public Health Association was used to evaluate the clinical effect of restoration, including the color of porcelain crowns, gingival inflammation, gingival margin discoloration, and crack or fracture. Data analysis was conducted with SPSS 20 software package for Student's t test and Chi-square test. Six cases were lost to follow-up. The patients who were treated with SLM deposition basal crowns (104 teeth) and cobalt chromium alloy casting base crowns (101 teeth) completed the study. Patients were more satisfied with SLM deposition cobalt chromium alloy porcelain crowns. There was 1 prosthesis with poor marginal fit after 24 months of restoration in SLM crowns. There were 6 prostheses with edge coloring and 8 with poor marginal fit in cobalt chromium alloy casting base crowns, which was significantly different between the 2 groups(P<0.05). The SLM deposition copings results in smaller edge coloring and better marginal fit than those of cobalt-chrome copings. Patients are pleased with short-term clinical results.

  14. Ab initio calculations of the structural, electronic, thermodynamic and thermal properties of BaSe1-x Te x alloys

    Science.gov (United States)

    Drablia, S.; Boukhris, N.; Boulechfar, R.; Meradji, H.; Ghemid, S.; Ahmed, R.; Omran, S. Bin; El Haj Hassan, F.; Khenata, R.

    2017-10-01

    The alkaline earth metal chalcogenides are being intensively investigated because of their advanced technological applications, for example in photoluminescent devices. In this study, the structural, electronic, thermodynamic and thermal properties of the BaSe1-x Te x alloys at alloying composition x = 0, 0.25, 0.50, 0.75 and 1 are investigated. The full potential linearized augmented plane wave plus local orbital method designed within the density functional theory was used to perform the total energy calculations. In this research work the effect of the composition on the results of the parameters and bulk modulus as well as on the band gap energy is analyzed. From our results, we found a deviation of the obtained results for the lattice constants from Vegard’s law as well as a deviation of the value of the bulk modulus from the linear concentration dependence. We also carried out a microscopic analysis of the origin of the band gap energy bowing parameter. Furthermore, the thermodynamic stability of the considered alloys was explored through the measurement of the miscibility critical temperature. The quasi-harmonic Debye model, as implemented in the Gibbs code, was used to predict the thermal properties of the BaSe1-x Te x alloys, and these investigations comprise our first theoretical predictions concerning the BaSe1-x Te x alloys.

  15. Hydrogen induced cracking tests of high strength steels and nickel-iron base alloys using the bolt-loaded specimen

    Energy Technology Data Exchange (ETDEWEB)

    Vigilante, G.N.; Underwood, J.H.; Crayon, D.; Tauscher, S.; Sage, T.; Troiano, E. [Army Armament RD and E Center, Watervliet, NY (United States). Benet Labs.

    1997-12-31

    Hydrogen induced cracking tests were conducted on high strength steels and nickel-iron base alloys using the constant displacement bolt-loaded compact specimen. The bolt-loaded specimen was subjected to both acid and electrochemical cell environments in order to produce hydrogen. The materials tested were A723, Maraging 200, PH 13-8 Mo, Alloy 718, Alloy 706, and A286, and ranged in yield strength from 760--1400 MPa. The effects of chemical composition, refinement, heat treatment, and strength on hydrogen induced crack growth rates and thresholds were examined. In general, all high strength steels tested exhibited similar crack growth rates and thresholds were examined. In general, all high strength steels tested exhibited similar crack growth rates and threshold levels. In comparison, the nickel-iron base alloys tested exhibited up to three orders of magnitude lower crack growth rates than the high strength steels tested. It is widely known that high strength steels and nickel base alloys exhibit different crack growth rates, in part, because of their different crystal cell structure. In the high strength steels tested, refinement and heat treatment had some effect on hydrogen induced cracking, though strength was the predominant factor influencing susceptibility to cracking. When the yield strength of one of the high strength steels tested was increased moderately, from 1130 MPa to 1275 MPa, the incubation times decreased by over two orders of magnitude, the crack growth rates increased by an order of magnitude, and the threshold stress intensity was slightly lower.

  16. Creep and stress rupture of a mechanically alloyed oxide dispersion and precipitation strengthened nickel-base superalloy

    Science.gov (United States)

    Howson, T. E.; Tien, J. K.; Mervyn, D. A.

    1980-01-01

    The creep and stress rupture behavior of a mechanically alloyed oxide dispersion strengthened (ODS) and gamma-prime precipitation strengthened nickel-base alloy (alloy MA 6000E) was studied at intermediate and elevated temperatures. At 760 C, MA 6000E exhibits the high creep strength characteristic of nickel-base superalloys and at 1093 C the creep strength is superior to other ODS nickel-base alloys. The stress dependence of the creep rate is very sharp at both test temperatures and the apparent creep activation energy measured around 760 C is high, much larger in magnitude than the self-diffusion energy. Stress rupture in this large grain size material is transgranular and crystallographic cracking is observed. The rupture ductility is dependent on creep strain rate, but usually is low. These and accompanying microstructural results are discussed with respect to other ODS alloys and superalloys and the creep behavior is rationalized by invoking a recently-developed resisting stress model of creep in materials strengthened by second phase particles.

  17. Detection and distribution of lithium in Mg-Li-Al based alloy by ToF-SIMS

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vinod, E-mail: vkt.meta@mnit.ac.in [Metallurgical and Materials Engineering, MNIT Jaipur, 302017 (India); Adjunct Faculty, Materials Research Centre, MNIT Jaipur, 302017 (India)

    2016-12-01

    Highlights: • First time, Time of Flight-Secondary Ion Mass Spectrometry (ToF-SIMS) is used to investigate the surface as well as bulk microstructural features of novel Mg-Li-Al based alloy. • There are six multi-oxide layers present within the surface film of LATZ9531R. • Secondary ion imaging by ToF-SIMS with mass contrast effect (including Li) is possible for a multiphase lithium-containing alloy systems. - Abstract: Time of Flight-Secondary Ion Mass Spectrometry (ToF-SIMS) is used to investigate the surface as well as bulk microstructural features of novel Mg-Li-Al based alloy namely Mg-9Li-7Al-3Sn-1Zn (LATZ9531). ToF-SIMS study indicates that there are six multi-oxide layers present within the surface film of LATZ9531. Furthermore, The presence of Li containing phase has been qualitatively confirmed based on the high number of Li-ion counts in SIMS, and the same is verified quantitatively by using electron probe microanalysis (EPMA). The novel approach may be useful to determine the chemical composition of the phases in various alloys which has lighter alloying elements such as lithium.

  18. Solidification characteristics and segregation behavior of a P-containing Ni-Fe-Cr-based alloy

    Science.gov (United States)

    Wang, Changshuai; Su, Haijun; Guo, YongAn; Guo, Jianting; Zhou, Lanzhang

    2017-09-01

    Solidification characteristics and segregation behavior of a P-containing Ni-Fe-Cr-based alloy, considered as boiler and turbine materials in 700 °C advanced ultra-supercritical coal-fired power plants, have been investigated by differential thermal analysis and directional solidification quenching technique. Results reveal that P decreases the solidus temperature, but only has negligible influence on liquidus temperature. After P was added, the solidification sequence has no apparent change, but the width of the mushy zone increases and dendritic structures become coarser. Moreover, P increases the amount and changes the morphology of MC carbide. Energy-dispersive spectroscopy analysis reveals that P has obvious influence on the segregation behavior of the constitute elements with equilibrium partition coefficients (ki) far away from unity, whereas has negligible effect on the constituent elements with ki close to unity and has more influence on the final stage of solidification than at early stage. The distribution profiles reveal that P atoms pile up ahead of the solid/liquid (S/L) interface and strongly segregate to the interdendritic liquid region. The influence of P on solidification characteristics and segregation behavior of Ni-Fe-Cr-based alloy could be attributed to the accumulation of P ahead of the S/L interface during solidification.

  19. Experimental Elucidation of the Oxygen Reduction Volcano in Base on a Pt Alloy Single Crystal

    DEFF Research Database (Denmark)

    Jensen, Kim Degn; Tymoczko, Jakub; Bandarenka, Aliaksandr S.

    2016-01-01

    the subsurface coverage of Cu we could tune the surface binding of the key reaction intermediate, OH; we thus monitored the OH binding energy shift through the observable shifts in the base voltammograms in both acidic and alkaline media. Further, we elucidate the experimental oxygen reduction volcano in 0.1 M......It is of fundamental importance to understand the factors controlling trends in activity for electrocatalytic reactions as a function of pH. In the case of the oxygen reduction reaction, numerous reports suggest significant divergences between noble metals surface catalytic performances in acid...... and base.[1,2] In our earlier studies, we mapped out the experimental Sabatier volcano for the oxygen reduction reaction in 0.1 M HClO4 using the Cu/Pt(111) near-surface alloy system, see Figure 1 for near-surface alloy schematic.[3,4] In this study, as those of [3,4], we found that by changing...

  20. Structure and Magnetic Properties in Ruthenium-Based Full-Heusler Alloys: AB INITIO Calculations

    Science.gov (United States)

    Bahlouli, S.; Aarizou, Z.; Elchikh, M.

    2013-12-01

    In this paper, we present ab initio calculations within density functional theory (DFT) to investigate structure, electronic and magnetic properties of Ru2CrZ (Z = Si, Ge and Sn) full-Heusler alloys. We have used the developed full-potential linearized muffin tin orbitals (FP-LMTO) based on the local spin density approximation (LSDA) with the PLane Wave expansion (PLW). In particular, we found that these Ruthenium-based Heusler alloys have the antiferromagnetic (AFM) type II as ground state. Then, we studied and discussed the magnetic properties belonging to our different magnetic structures: AFM type II, AFM type I and ferromagnetic (FM) phase. We also found that Ru2CrSi and Ru2CrGe exhibit a semiconducting behavior whereas Ru2CrSn has a semimetallic-like behavior as it is experimentally found. We made an estimation of Néel temperatures (TN) in the framework of the mean-field theory and used the energy differences approach to deduce the relevant short-range nearest-neighbor (J1) and next-nearest-neighbor (J2) interactions. The calculated TN are somewhat overestimated to the available experimental ones.

  1. Fabrication and corrosion resistance of Mg-Zn-Y-based nano-quasicrystals alloys

    Directory of Open Access Journals (Sweden)

    Zhifeng Wang

    2012-02-01

    Full Text Available A wedge-shaped copper mold was used to fabricate micro quasicrystals(QCs. Stable Mg-Zn-Y-based nano-QCs were directly synthesized through this simple route instead of crystallization from metallic glasses or complicated forming processes at high temperature. The study showed that on the tips of the wedge-shaped ingots, the minimum diameter of nano-QCs approach to 4~6 nm. The main size of nano-QCs is about 10~30 nm. The maximum microhardness of QCs has been dramatically improved to about HV440 which increased by about 280% compared with that of the petal-like QCs fabricated under common cast iron mold cooling conditions. Possessing a certain negative enthalpy of mixing and existence of Frank-Kasper-type phases determined the formation of Mg-Zn-Y-based nano-QCs. The further electrochemical studies showed that Mg71Zn26Y2Cu1 nano-QC alloy possess high corrosion resistance in simulated seawater and its corrosion resistance is much better than those of the Mg72Zn26Y2 and Mg71Zn26Y2Cu0.5 Ni0.5 nano-QC alloys.

  2. Analysis of wear properties of aluminium based journal bearing alloys with and without lubrication.

    Science.gov (United States)

    Mathavan, J. Joy; Patnaik, Amar

    2016-09-01

    Apart from classical bearing materials, Aluminium alloys are used as bearing materials these days because of their superior quality. In this analysis, new Aluminium based bearing materials, with filler metals Si, Ni, and Cr are prepared by metal mould casting in burnout furnace machine, and tribological properties of these alloys with and without lubrication were tested. The experiments for wear with lubrication are conducted on multiple specimen tester and experiments without lubrication is conducted on Pin on disk tribometer. The disc material used was SAE 1050 steel. Wear tests were conducted at a sliding speed of 0.785 m/s and at a normal load of 20 N. Coefficient of friction values, temperature changes and wear of the specimens were plotted on graph according to the above mentioned working conditions. Hardness and weight losses of the specimens were calculated. The obtained results demonstrate how the friction and wear properties of these samples have changed with the % addition of Silicon, Chromium and Nickel to the base metal aluminium.

  3. Surface Engineering of Mo-Base Alloys for Elevated-Temperature Environmental Resistance

    Science.gov (United States)

    Perepezko, J. H.

    2015-07-01

    The synthesis of robust coatings that provide protection against environmental attack at ultrahigh temperatures is a difficult challenge. To achieve this goal for Mo-base alloys, the fundamental concepts of reactive diffusion pathway analysis and kinetic biasing are used to design a multilayer Mo-Si-B-base coating with a phase sequencing that allows for structural and thermodynamic compatibility and an underlying diffusion barrier to maintain coating integrity. The coating design concepts have a general applicability. The coating structure evolution during high-temperature exposure facilitates a prolonged lifetime as well as self-healing capability. The borosilicide coatings that can be synthesized by a pack cementation process yield superior environmental resistance for Mo-base systems at temperatures up to at least 1,700°C and can be adapted to apply to other refractory metal and ceramic systems.

  4. Microstructure Characteristics and Properties of HVOF Sprayed Ni-Based Alloy Nano-h-BN Self-Lubricating Composite Coatings

    OpenAIRE

    Xiaofeng Zhang; Long Zhang; Zhenyi Huang

    2015-01-01

    A Ni-based alloy/nano-h-BN self-lubricating composite coating was produced on medium carbon steel by high velocity oxygen fuel (HVOF) spraying technique. The powder feedstocks for HVOF spraying were prepared by ball milling and agglomerated the nano-h-BN with Ni-based alloy powders. The microstructure and mechanical properties of coatings have been investigated. With the increasing of h-BN contents, some delaminations appeared gradually in the coatings and a continuous network with h-BN phase...

  5. Tribological Potential of Hybrid Composites Based on Zinc and Aluminium Alloys Reinforced with SiC and Graphite Particles

    Directory of Open Access Journals (Sweden)

    D. Džunić

    2012-12-01

    Full Text Available The paper reviews contemporary research in the area of hybrid composites based on zinc and aluminium alloys reinforced with SiC and graphite particles. Metal matrix composites (MMCs based on ZA matrix are being increasingly applied as light-weight and wear resistant materials. Aluminium matrix composites with multiple reinforcements (hybrid AMCsare finding increased applications because of improved mechanical and tribological properties and hence are better substitutes for single reinforced composites. The results of research show that the hybrid composites possess higher hardness, higher tensile strength, better wear resistance and lower coefficient of friction when compared to pure alloys.

  6. Probability of Occurrence of Life-Limiting Fatigue Mechanism in P/M Nickel-Based Alloys (Postprint)

    Science.gov (United States)

    2016-03-30

    Microstructures 8 and 9 in Figure 3(b) can be considered to correspond to the " Small " and "Large" seeded specimens under no peening with volumetric...AFRL-RX-WP-JA-2017-0146 PROBABILITY OF OCCURRENCE OF LIFE-LIMITING FATIGUE MECHANISM IN P/M NICKEL-BASED ALLOYS (POSTPRINT) M.J...February 2016 4. TITLE AND SUBTITLE PROBABILITY OF OCCURRENCE OF LIFE-LIMITING FATIGUE MECHANISM IN P/M NICKEL-BASED ALLOYS (POSTPRINT) 5a

  7. Effect of Different Irrigation Solutions on the Colour Stability of Three Calcium Silicate-Based Materials.

    Science.gov (United States)

    F, Sobhnamayan; A, Adl; S, Ghanbaran

    2017-06-01

    Previous studies have shown discoloration of mineral trioxide aggregate (MTA) in contact with root canal irrigation solutions. However, there are limited data on colour stability of other calcium silicate-based materials (CSMs). This in vitro study aimed to evaluate the colour stability of three CSMs in contact with different irrigation solutions. Three CSMs including White MTA (wMTA) Angelus, calcium enriched mixture (CEM), and Biodentine were assessed in this study. Forty five samples of each material were mixed according to the manufactures' instructions and then placed in silicone tubes. After 24 hours, the materials were removed from the moulds and 9 samples of each material left dry or immersed in normal saline, 5% sodium hypochlorite (NaOCL), 2% chlorhexidinegluconate (CHX), or 17%EDTA for 24 hours. Colour changes were measured with a spectrophotometer. Data were evaluated with 2-way analysis of variance, one way analysis of variance and Tukey post hoc tests. The highest discoloration of all materials was observed after contact with CHX. In the MTA Angelus and CEM cement groups, significant differences were observed between CHX and NaOCl and also between these two irrigants with the other three irrigants ( p < 0.05). In the Biodentine group, CHX created statistically significant discoloration compared to other irrigants ( p < 0.05). Only wMTA Angelus showed a significantly higher discoloration in contact with EDTA compared to normal saline and dry condition ( p < 0.05). wMTA Angelus showed a significantly higher colour change compared with CEM cement and Biodentine after contact with NaOCl, CHX, and EDTA ( p < 0.05). The contact of wMTA, CEM cement, and Biodentine with CHX should be avoided because this leads to severe discoloration. Contact with sodium hypochlorite also leads to discoloration of wMTA and CEM cements. Among of the three tested materials, wMTA showed the highest discoloration after contact with NaOCl, CHX, and EDTA.

  8. Bi-layered calcium phosphate cement-based composite scaffold mimicking natural bone structure

    Directory of Open Access Journals (Sweden)

    Fupo He and Jiandong Ye

    2013-01-01

    Full Text Available In this study, a core/shell bi-layered calcium phosphate cement (CPC-based composite scaffold with adjustable compressive strength, which mimicked the structure of natural cortical/cancellous bone, was fabricated. The dense tubular CPC shell was prepared by isostatic pressing CPC powder with a specially designed mould. A porous CPC core with unidirectional lamellar pore structure was fabricated inside the cavity of dense tubular CPC shell by unidirectional freeze casting, followed by infiltration of poly(lactic-co-glycolic acid and immobilization of collagen. The compressive strength of bi-layered CPC-based composite scaffold can be controlled by varying thickness ratio of dense layer to porous layer. Compared to the scaffold without dense shell, the pore interconnection of bi-layered scaffold was not obviously compromised because of its high unidirectional interconnectivity but poor three dimensional interconnectivity. The in vitro results showed that the rat bone marrow stromal cells attached and proliferated well on the bi-layered CPC-based composite scaffold. This novel bi-layered CPC-based composite scaffold is promising for bone repair.

  9. Biocompatibility of dental alloys

    Energy Technology Data Exchange (ETDEWEB)

    Braemer, W. [Heraeus Kulzer GmbH and Co. KG, Hanau (Germany)

    2001-10-01

    Modern dental alloys have been used for 50 years to produce prosthetic dental restorations. Generally, the crowns and frames of a prosthesis are prepared in dental alloys, and then veneered by feldspar ceramics or composites. In use, the alloys are exposed to the corrosive influence of saliva and bacteria. Metallic dental materials can be classified as precious and non-precious alloys. Precious alloys consist of gold, platinum, and small amounts of non-precious components such as copper, tin, or zinc. The non-precious alloys are based on either nickel or cobalt, alloyed with chrome, molybdenum, manganese, etc. Titanium is used as Grade 2 quality for dental purposes. As well as the dental casting alloys, high purity electroplated gold (99.8 wt.-%) is used in dental technology. This review discusses the corrosion behavior of metallic dental materials with saliva in ''in vitro'' tests and the influence of alloy components on bacteria (Lactobacillus casei and Streptococcus mutans). The test results show that alloys with high gold content, cobalt-based alloys, titanium, and electroplated gold are suitable for use as dental materials. (orig.)

  10. Success Rates of Pulpotomies in Primary Molars Using Calcium Silicate-Based Materials: A Randomized Control Trial

    National Research Council Canada - National Science Library

    Yeliz Guven; Sermin Dicle Aksakal; Nilufer Avcu; Gulcan Unsal; Elif Bahar Tuna; Oya Aktoren

    2017-01-01

    Objective. The aim of this study was to evaluate and compare, both clinically and radiographically, the effects of calcium silicate-based materials (i.e., ProRoot MTA [PR-MTA], MTA-Plus [MTA-P], and Biodentine [BD...

  11. Effect of Microstructure on the Hot Deformation Behavior of TiAl-Based Alloys Prepared by Powder Metallurgy Method

    Science.gov (United States)

    Wang, DongJun; Zhang, Rui; Yuan, Hao; Qiang, JianMing

    2017-10-01

    To investigate microstructural influence on deformation behavior, TiAl-based alloys were prepared by spark plasma sintering and heat treatment was conducted to optimize the microstructures of as-sintered samples. The near-γ microstructure of the sintered alloy transformed into a duplex microstructure after heat treatment. Furthermore, isothermal compression tests were carried out at different temperatures in the range 1100-1200°C with a strain rate of 0.01 s-1. The resistances to deformation of the heat-treated samples were smaller than those of the as-sintered samples under the same deformation conditions. In particular, the heat-treated sample had fewer and smaller α2 phases than did the sintered alloy, and it exhibited a well-deformed appearance and homogeneous microstructure after deformation at a temperature 100°C lower than the sintered alloy. The results revealed that TiAl-based alloys with an optimal microstructure fabricated by powder metallurgy had good formability and a homogeneous deformed microstructure, which was preferable for hot-working and further secondary processing.

  12. Observations on the oxidation of Mn-modified Ni-base Haynes 230 alloy under SOFC exposure conditions

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Z Gary; Xia, Gordon; Stevenson, Jeffry W.; Singh, Prabhakar

    2005-07-01

    The commercial Ni-base Haynes 230 alloy (Ni-Cr-Mo-W-Mn) was modified with two increased levels of Mn (1 and 2 wt per cent) and evaluated for its oxidation resistance under simulated SOFC interconnect exposure conditions. Oxidation rate, oxide morphology, oxide conductivity and thermal expansion were measured and compared with commercial Haynes 230. It was observed that additions of higher levels of Mn to the bulk alloy facilitated the formation of a bi-layered oxide scale that was comprised of an outer M3O4 (M=Mn, Cr, Ni) spinel-rich layer at the oxide – gas interface over a Cr2O3-rich sub-layer at the metal – oxide interface. The modified alloys showed higher oxidation rates and the formation of thicker oxide scales compared to the base alloy. The formation of a spinel-rich top layer improved the scale conductivity, especially during the early stages of the oxidation, but the higher scale growth rate resulted in an increase in the area-specific electrical resistance over time. Due to their face-centered cubic crystal structure, both commercial and modified alloys demonstrated a coefficient of thermal expansion that was higher than that of typical anode-supported and electrolyte-supported SOFCs.

  13. Microstructure and Properties of W-Cu Composite/Fe-Based Powder Alloy Vacuum Brazed Joint with Different Filler Metals

    Science.gov (United States)

    Xia, C. Z.; Yang, J.; Xu, X. P.; Zou, J. S.

    2017-05-01

    W-Cu composite and Fe-based powder alloy were brazed with filler metals of Ag-Cu and Cu-Mn-Co alloys in a vacuum furnace. Both of filler metals can join W-Cu composite with Fe-based powder alloy directly in the experiment process. Microstructure, distribution of elements and fracture morphology were observed and analyzed using scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) methods, and phase composition of bonding area was analyzed by X-ray diffraction (XRD). The obtained results indicated that the smooth faying surface and dense microstructure of brazed joint were formed and the primary microstructure of brazing seam were, respectively, Ag(Cu) solid solution and Cu(Mn) solid solution, which ensured forming the stable connection of brazed joint. The bending strength of Ag-based and Cu-based brazed joint can, respectively, reach to 317 and 704 MPa, where fracture showed a typical ductile fracture characteristic. The fracture of Cu-based brazed joint located at brazing seam area, and the fracture of Ag-based brazed joint occurred in Fe-based powder alloy side.

  14. Effect of Mo on properties of the industrial Fe-B-alloy-derived Fe-based bulk metallic glasses

    Science.gov (United States)

    Zhu, Kai-rui; Jiang, Wei; Wu, Ji-li; Zhang, Bo

    2017-08-01

    The experimental results concerning the effects of Mo on the glass-forming ability (GFA), thermal stability, and mechanical, anticorrosion, and magnetic properties of an (Fe71.2B24Y4.8)96Nb4 bulk metallic glass (BMG) were presented. An industrial Fe-B alloy was used as the raw material, and a series of Fe-based BMGs were synthesized. In BMGs with the Mo contents of approximately 1at%-2at%, the cast alloy reached a critical diameter of 6 mm. The hardness and fracture strength also reached their maximum values in this alloy system. However, the anticorrosion and magnetic properties of the BMGs were not substantially improved by the addition of Mo. The low cost, good GFA, high hardness, and high fracture strength of the Fe-based BMGs developed in this work suggest that they are potential candidates for commercial applications.

  15. Synthesis and formation process of Al2CuHx: A new class of interstitial aluminum-based alloy hydride

    Directory of Open Access Journals (Sweden)

    Hiroyuki Saitoh

    2013-09-01

    Full Text Available Aluminum-based alloy hydride Al2CuHx (x ∼ 1 is synthesized by hydrogenating Al2Cu alloy using high-temperature and high-pressure hydrogen atmosphere. Al8Cu square antiprisms in Al2Cu twist around the c axis of a tetragonal unit cell by hydrogenation. The twist enlarges the interstitial spaces for accommodating hydrogen atoms which align linearly parallel to the c axis in Al2CuHx. Thermodynamic stability of Al2CuHx results from the balance of stabilization by H 1s and Al 3sp hybridization and destabilization owing to the Fermi-level lifting upon hydrogenation. The crystal and electronic structures of Al2CuHx illustrate the formation of an interstitial hydride of aluminum-based alloy.

  16. Artificial patina formation onto copper-based alloys: Chloride and sulphate induced corrosion processes

    Science.gov (United States)

    Di Carlo, G.; Giuliani, C.; Riccucci, C.; Pascucci, M.; Messina, E.; Fierro, G.; Lavorgna, M.; Ingo, G. M.

    2017-11-01

    Naturally grown patinas are typically detected onto the surface of modern copper-based artefacts and strictly affect their surface reactivity and appearance. The production of representative patinas is a key issues in order to obtain model systems which can be used for the development and validation of appropriate conservation materials and methods. In this study, we have prepared different artificial representative patinas by using a quaternary Cu-Sn-Zn-Pb alloy with chemical composition and metallurgical features similar to those of valuable modern works of art. In order to produce degradation products usually observed onto their surface, chloride and sulphate species were used to induce corrosion processes. Different patinas were produced by changing the nature of corrosive species and the set-up for the accelerated degradation. The composition and structural properties of the patinas were investigated by attenuated total reflectance Fourier transform infrared spectroscopy, X-ray diffraction, optical microscopy and scanning electron microscopy combined with energy dispersive X-ray spectroscopy. The results allow to identify degradation products and to distinguish copper hydroxychloride polymorphs and copper hydroxysulphates with similar structure. Our findings show that patina composition can be tailored by modifying the degradation procedure and patinas representative of modern artefacts made of quaternary Cu-Sn-Zn-Pb alloy can be obtained.

  17. Steel Alloy Hot Roll Simulations and Through-Thickness Variation Using Dislocation Density-Based Modeling

    Science.gov (United States)

    Jansen Van Rensburg, G. J.; Kok, S.; Wilke, D. N.

    2017-10-01

    Different roll pass reduction schedules have different effects on the through-thickness properties of hot-rolled metal slabs. In order to assess or improve a reduction schedule using the finite element method, a material model is required that captures the relevant deformation mechanisms and physics. The model should also report relevant field quantities to assess variations in material state through the thickness of a simulated rolled metal slab. In this paper, a dislocation density-based material model with recrystallization is presented and calibrated on the material response of a high-strength low-alloy steel. The model has the ability to replicate and predict material response to a fair degree thanks to the physically motivated mechanisms it is built on. An example study is also presented to illustrate the possible effect different reduction schedules could have on the through-thickness material state and the ability to assess these effects based on finite element simulations.

  18. Shape memory alloy-based small crawling robots inspired by C. elegans

    Energy Technology Data Exchange (ETDEWEB)

    Yuk, Hyunwoo; Kim, Daeyeon; Shin, Jennifer H [Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon (Korea, Republic of); Lee, Honggu; Jo, Sungho, E-mail: shjo@kaist.ac.kr, E-mail: j_shin@kaist.ac.kr [Department of Computer Science, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon (Korea, Republic of)

    2011-12-15

    Inspired by its simple musculature, actuation and motion mechanisms, we have developed a small crawling robot that closely mimics the model organism of our choice: Caenorhabditis elegans. A thermal shape memory alloy (SMA) was selected as an actuator due to the similarities of its properties to C. elegans muscles. Based on the anatomy of C. elegans, a 12-unit robot was designed to generate a sinusoidal undulating motion. Each body unit consisting of a pair of SMA actuators is serially connected by rigid links with an embedded motion control circuit. A simple binary operation-based motion control mechanism was implemented using a microcontroller. The assembled robot can execute C. elegans-like motion with a 0.17 Hz undulation frequency. Its motion is comparable to that of a real worm.

  19. Fabrication of Biodegradable Low Elastic Porous Mg-Zn-Mn-HA Alloy by Spark Plasma Sintering for Orthopaedic Applications

    Science.gov (United States)

    Pal Singh, Bhupinder; Singh, Ramandeep; Mehta, J. S.; Prakash, Chander

    2017-08-01

    In the present research work, porous Mg-Zn-Mn-HA alloy was successfully fabricated by mechanical alloying of magnesium (Mg), manganese (Mn), zinc (Zn), and hydroxyapatite (HA) powders followed by consolidation using Spark Plasma Sintering technique. The microstructure, surface topography, and element composition of the Mg-Zn-Mn-HA alloy was investigated using optical microscope, field-emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The micro-hardness of the specimens was measured on a Vickers hardness tester. The microstructure and FESEM examination of the compact revealed that the alloy distinctly shows the porosities in the microstructure. It was observed that complex reactions between HA and alloy elements occurred during the sintering process of Mg-Zn-Mn-HA alloy and biocompatible phases such as Manganese Oxide ((MnO)0.441 (CaO)0.559), Mg0.97 Zn0.03, Manganese Phosphide (Mn1.9 P), Calcium Manganese Oxide (Ca2 Mn8 O16), and Zincite (ZnO2) were generated in the compact, which is beneficial to form apatite and improved the bioactivity of the alloy for osseiointegartion. The fabricated Mg-Zn-Mn-HA alloy exhibits maximum micro-hardness (∼97 HV), which is very high value as compared to the alloys reported in literature. Based on these above observations, it is expected that the as-fabricated Mg-Zn-Mn-HA alloy is suggested for orthopaedic applications.

  20. Creep Resistant Zinc Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Frank E. Goodwin

    2002-12-31

    This report covers the development of Hot Chamber Die Castable Zinc Alloys with High Creep Strengths. This project commenced in 2000, with the primary objective of developing a hot chamber zinc die-casting alloy, capable of satisfactory service at 140 C. The core objectives of the development program were to: (1) fill in missing alloy data areas and develop a more complete empirical model of the influence of alloy composition on creep strength and other selected properties, and (2) based on the results from this model, examine promising alloy composition areas, for further development and for meeting the property combination targets, with the view to designing an optimized alloy composition. The target properties identified by ILZRO for an improved creep resistant zinc die-casting alloy were identified as follows: (1) temperature capability of 1470 C; (2) creep stress of 31 MPa (4500 psi); (3) exposure time of 1000 hours; and (4) maximum creep elongation under these conditions of 1%. The project was broadly divided into three tasks: (1) Task 1--General and Modeling, covering Experimental design of a first batch of alloys, alloy preparation and characterization. (2) Task 2--Refinement and Optimization, covering Experimental design of a second batch of alloys. (3) Task 3--Creep Testing and Technology transfer, covering the finalization of testing and the transfer of technology to the Zinc industry should have at least one improved alloy result from this work.

  1. NASA-UVa light aerospace alloy and structure technology program supplement: Aluminum-based materials for high speed aircraft

    Science.gov (United States)

    Starke, E. A., Jr.

    1993-01-01

    This report on the NASA-UVa Light Aerospace Alloy and Structure Technology Program Supplement: Aluminum-Based Materials for High Speed Aircraft covers the period from January 1, 1992 to June 30, 1992. The objective of the research is to develop aluminum alloys and aluminum matrix composites for the airframe which can efficiently perform in the HSCT environment for periods as long as 60,000 hours (certification for 120,000 hours) and, at the same time, meet the cost and weight requirements for an economically viable aircraft. Current industry baselines focus on flight at Mach 2.4. The research covers four major materials systems: (1) ingot metallurgy 2XXX, 6XXX, and 8XXX alloys, (2) powder metallurgy 2XXX alloys, (3) rapidly solidified, dispersion strengthened Al-Fe-X alloys, and (4) discontinuously reinforced metal matrix composites. There are ten major tasks in the program which also include evaluation and trade-off studies by Boeing and Douglas aircraft companies.

  2. Structural, electronic, magnetic and optical properties of Ni,Ti/Al-based Heusler alloys. A first-principles approach

    Energy Technology Data Exchange (ETDEWEB)

    Adebambo, Paul O. [Univ. of Agriculture. Abeokuta (Nigeria). Dept. of Physics; McPherson Univ., Abeokuta (Nigeria). Dept. of Physical and Computer Sciences; Adetunji, Bamidele I. [Univ. of Agriculture. Abeokuta (Nigeria). Dept. of Physics; Bells Univ. of Technology, Oto (Nigeria). Dept. of Mathematics; Olowofela, Joseph A. [Univ. of Agriculture. Abeokuta (Nigeria). Dept. of Physics; Oguntuase, James A. [Univ. of Agriculture. Abeokuta (Nigeria). Dept. of Mathematics; Adebayo, Gboyega A. [Univ. of Agriculture. Abeokuta (Nigeria). Dept. of Physics; Abdus Salam International Centre for Theoretical Physics, Trieste (Italy)

    2016-05-01

    In this work, detailed first-principles calculations within the generalised gradient approximation (GGA) of electronic, structural, magnetic, and optical properties of Ni,Ti, and Al-based Heusler alloys are presented. The lattice parameter of C1{sub b} with space group F anti 43m (216) NiTiAl alloys is predicted and that of Ni{sub 2}TiAl is in close agreement with available results. The band dispersion along the high symmetry points W→L→Γ→X→W→K in Ni{sub 2}TiAl and NiTiAl Heusler alloys are also reported. NiTiAl alloy has a direct band gap of 1.60 eV at Γ point as a result of strong hybridization between the d state of the lower and higher valence of both the Ti and Ni atoms. The calculated real part of the dielectric function confirmed the band gap of 1.60 eV in NiTiAl alloys. The present calculations revealed the paramagnetic state of NiTiAl. From the band structure calculations, Ni{sub 2}TiAl with higher Fermi level exhibits metallic properties as in the case of both NiAl and Ni{sub 3}Al binary systems.

  3. Contribution to the Study of the Relation between Microstructure and Electrochemical Behavior of Iron-Based FeCoC Ternary Alloys

    Directory of Open Access Journals (Sweden)

    Farida Benhalla-Haddad

    2012-01-01

    Full Text Available This work deals with the relation between microstructure and electrochemical behavior of four iron-based FeCoC ternary alloys. First, the arc-melted studied alloys were characterized using differential thermal analyses and scanning electron microscopy. The established solidification sequences of these alloys show the presence of two primary crystallization phases (δ(Fe and graphite as well as two univariante lines : peritectic L+(Fe↔(Fe and eutectic L↔(Fe+Cgraphite. The ternary alloys were thereafter studied in nondeaerated solution of 10−3 M NaHCO3 + 10−3 M Na2SO4, at 25°C, by means of the potentiodynamic technique. The results indicate that the corrosion resistance of the FeCoC alloys depends on the carbon amount and the morphology of the phases present in the studied alloys.

  4. Contribution to the Study of the Relation between Microstructure and Electrochemical Behavior of Iron-Based FeCoC Ternary Alloys

    Science.gov (United States)

    Benhalla-Haddad, Farida; Amara, Sif Eddine; Benchettara, Abdelkader; Taibi, Kamel; Kesri, Rafika

    2012-01-01

    This work deals with the relation between microstructure and electrochemical behavior of four iron-based FeCoC ternary alloys. First, the arc-melted studied alloys were characterized using differential thermal analyses and scanning electron microscopy. The established solidification sequences of these alloys show the presence of two primary crystallization phases (δ(Fe) and graphite) as well as two univariante lines : peritectic L + δ(Fe)↔γ(Fe) and eutectic L↔γ(Fe) + Cgraphite. The ternary alloys were thereafter studied in nondeaerated solution of 10−3 M NaHCO3 + 10−3 M Na2SO4, at 25°C, by means of the potentiodynamic technique. The results indicate that the corrosion resistance of the FeCoC alloys depends on the carbon amount and the morphology of the phases present in the studied alloys. PMID:22448342

  5. Prediction of calcium carbonate precipitation in oilfields based on a fuzzy solubility model

    Energy Technology Data Exchange (ETDEWEB)

    Khatami, H.R.; Ranjbar, M. [S.B. Kerman Univ. (Iran). Dept. of Mining Engineering; Schaffie, M. [S.B. Kerman Univ. (Iran). Dept. of Chemical Engineering; Emadi, M.A. [National Iranian Oil Company, Tehran (Iran)

    2008-06-15

    The ability of fuzzy logic in treating uncertainty and imprecision is used to simulate the influence of temperature and partial pressure of carbon dioxide on the solubility of calcium carbonate. The scaling tendency for calcium carbonate due to change in physical conditions of four Iranian oilfields is determined by means of the developed fuzzy solubility model. Calculation of saturation index for the fields shows a considerable risk of calcium carbonate deposition. A fuzzy truth value graph is also proposed in order to provide an interpretation for the obtained saturation index values and to recommend suitable action for scale prevention and inhibition. (orig.)

  6. Influences of iron and calcium carbonate on wastewater treatment performances of algae based reactors.

    Science.gov (United States)

    Zhao, Zhimiao; Song, Xinshan; Wang, Wei; Xiao, Yanping; Gong, Zhijie; Wang, Yuhui; Zhao, Yufeng; Chen, Yu; Mei, Mengyuan

    2016-09-01

    The influences of iron and calcium carbonate (CaCO3) addition in wastewater treatments reactors performance were investigated. Adding different concentrations of Fe(3+) (5, 10, 30 and 50mmol/m(3)), iron and CaCO3 powder led to changes in algal characteristics and physico-chemical and microbiological properties. According to the investigation results, nutrient removal efficiency in algae based reactors was obviously increased by the addition of 10mmol/m(3) Fe(3+), iron (5mmol/m(3)) and CaCO3 powder (0.2gm(-3)) and the removal efficiencies of BOD5, TN, and TP in Stage 2 were respectively increased by 28%, 8.9%, and 22%. The improvements in physico-chemical performances were verified by microbial community tests (bacteria quantity, activity and community measured in most probable number, extracellular enzymes activity, and Biolog Eco Plates). Microbial variations indicated the coexistence of Fe ions and carbonate-bicarbonate, which triggered the synergistic effect of physico-chemical action and microbial factors in algae based reactors. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Combined effect of nanoscale grain size and porosity on lattice thermal conductivity of bismuth-telluride-based bulk alloys

    Science.gov (United States)

    Takashiri, Masayuki; Tanaka, Saburo; Hagino, Harutoshi; Miyazaki, Koji

    2012-10-01

    Here, we investigate the combined effect of the nanoscale crystal grains and porosity on the lattice thermal conductivity of bismuth-telluride-based bulk alloys using both experimental studies and modeling. The fabricated bulk alloys exhibit average grain sizes of 30 size effect in combination with the Maxwell-Garnett model for the porosity effect. The results of this combined model are consistent with the experimental results, and it shows that the grain size effect in the nanoscale regime accounts for a significant portion of the reduction in lattice thermal conductivity.

  8. Roles of Co element in Fe-based bulk metallic glasses utilizing industrial FeB alloy as raw material

    Directory of Open Access Journals (Sweden)

    Shouyuan Wang

    2017-08-01

    Full Text Available A series of Fe-based bulk metallic glasses were fabricated by a conventional copper mold casting method using a kind of Fe-B industrial raw alloy. It is found that Fe-B-Y-Nb bulk metallic glass with 3 at% of Co addition possesses the best glass forming ability, thermal stability, hardness, magnetic property and anti-corrosion property. The hardness test result indicates a synchronically trend with glass-forming ability parameters. The excellent glass-forming ability and a combination of good mechanical and functional properties suggest that the alloys in this work might be good candidates for commercial use.

  9. Hot-working behavior of an advanced intermetallic multi-phase γ-TiAl based alloy

    Energy Technology Data Exchange (ETDEWEB)

    Schwaighofer, Emanuel, E-mail: emanuel.schwaighofer@unileoben.ac.at [Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Roseggerstr. 12, A-8700 Leoben (Austria); Clemens, Helmut [Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Roseggerstr. 12, A-8700 Leoben (Austria); Lindemann, Janny [Chair of Physical Metallurgy and Materials Technology, Brandenburg University of Technology, Konrad-Wachsmann-Allee 17, D-03046 Cottbus (Germany); GfE Fremat GmbH, Lessingstr. 41, D-09599 Freiberg (Germany); Stark, Andreas [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Str. 1, D-21502 Geesthacht (Germany); Mayer, Svea [Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Roseggerstr. 12, A-8700 Leoben (Austria)

    2014-09-22

    New high-performance engine concepts for aerospace and automotive application enforce the development of lightweight intermetallic γ-TiAl based alloys with increased high-temperature capability above 750 °C. Besides an increased creep resistance, the alloy system must exhibit sufficient hot-workability. However, the majority of current high-creep resistant γ-TiAl based alloys suffer from poor workability, whereby grain refinement and microstructure control during hot-working are key factors to ensure a final microstructure with sufficient ductility and tolerance against brittle failure below the brittle-to-ductile transition temperature. Therefore, a new and advanced β-solidifying γ-TiAl based alloy, a so-called TNM alloy with a composition of Ti–43Al–4Nb–1Mo–0.1B (at%) and minor additions of C and Si, is investigated by means of uniaxial compressive hot-deformation tests performed with a Gleeble 3500 simulator within a temperature range of 1150–1300 °C and a strain rate regime of 0.005–0.5 s{sup −1} up to a true deformation of 0.9. The occurring mechanisms during hot-working were decoded by ensuing constitutive modeling of the flow curves by a novel phase field region-specific surface fitting approach via a hyperbolic-sine law as well as by evaluation through processing maps combined with microstructural post-analysis to determine a safe hot-working window of the refined TNM alloy. Complementary, in situ high energy X-ray diffraction experiments in combination with an adapted quenching and deformation dilatometer were conducted for a deeper insight about the deformation behavior of the alloy, i.e. phase fractions and texture evolution as well as temperature uncertainties arising during isothermal and non-isothermal compression. It was found that the presence of β-phase and the contribution of particle stimulated nucleation of ζ-Ti{sub 5}Si{sub 3} silicides and h-type carbides Ti{sub 2}AlC enhance the dynamic recrystallization behavior during

  10. Synthesis of Micro- and Nanoparticles of Metal Oxides and Their Application for Reinforcement of Al-Based Alloys

    Directory of Open Access Journals (Sweden)

    S. Vorozhtsov

    2015-01-01

    Full Text Available This paper presents a comparative analysis of morphology, chemical and phase compositions, and particle size distribution of nanopowders produced by electric explosion of wire (EEW and plasma-chemical methods. The possibility of introduction of Al2O3 particles into Al alloy by means of a special master alloy and with ultrasonic processing is shown. The improvement of tensile properties of an Al-based composite material reinforced with 0.1 wt% of EEW Al2O3 is demonstrated.

  11. Oxide Dispersion Strengthened Fe(sub 3)Al-Based Alloy Tubes: Application Specific Development for the Power Generation Industry

    Energy Technology Data Exchange (ETDEWEB)

    Kad, B.K.

    1999-07-01

    A detailed and comprehensive research and development methodology is being prescribed to produce Oxide Dispersion Strengthened (ODS)-Fe3Al thin walled tubes, using powder extrusion methodologies, for eventual use at operating temperatures of up to 1100C in the power generation industry. A particular 'in service application' anomaly of Fe3Al-based alloys is that the environmental resistance is maintained up to 1200C, well beyond where such alloys retain sufficient mechanical strength. Grain boundary creep processes at such high temperatures are anticipated to be the dominant failure mechanism.

  12. Corrosion resistance of nickel-based alloys in salt and metal melts containing REE

    Science.gov (United States)

    Abramov, A. V.; Karpov, V. V.; Zhilyakov, A. Yu.; Belikov, S. V.; Volkovich, V. A.; Polovov, I. B.; Rebrin, O. I.

    2017-09-01

    The corrosion resistance of Hastelloy G-35 and VDM® Alloy 625 nickel alloys was studied in a wide temperature range (750-1100 °C) in fused LiCl, CaCl2, NaCl-KCl, LiF mixtures containing REE. The rates and the mechanisms of the corrosion of the materials studied were determined. The processes taking place during the interaction between alloys and melts were investigated.

  13. Optimization of In-Situ Shot-Peening-Assisted Cold Spraying Parameters for Full Corrosion Protection of Mg Alloy by Fully Dense Al-Based Alloy Coating

    Science.gov (United States)

    Wei, Ying-Kang; Luo, Xiao-Tao; Li, Cheng-Xin; Li, Chang-Jiu

    2017-01-01

    Magnesium-based alloys have excellent physical and mechanical properties for a lot of applications. However, due to high chemical reactivity, magnesium and its alloys are highly susceptible to corrosion. In this study, Al6061 coating was deposited on AZ31B magnesium by cold spray with a commercial Al6061 powder blended with large-sized stainless steel particles (in-situ shot-peening particles) using nitrogen gas. Microstructure and corrosion behavior of the sprayed coating was investigated as a function of shot-peening particle content in the feedstock. It is found that by introducing the in-situ tamping effect using shot-peening (SP) particles, the plastic deformation of deposited particles is significantly enhanced, thereby resulting in a fully dense Al6061 coating. SEM observations reveal that no SP particle is deposited into Al6061 coating at the optimization spraying parameters. Porosity of the coating significantly decreases from 10.7 to 0.4% as the SP particle content increases from 20 to 60 vol.%. The electrochemical corrosion experiments reveal that this novel in-situ SP-assisted cold spraying is effective to deposit fully dense Al6061 coating through which aqueous solution is not permeable and thus can provide exceptional protection of the magnesium-based materials from corrosion.

  14. CRITERIA FOR SELECTION OF ALLOYING COMPONENTS AND BASE COMPOSITIONS FOR MANUFACTURING OF MECHANICALLY ALLOYED DISPERSION-STRENGTHENED MATERIALS ON THE BASIS OF METALS

    Directory of Open Access Journals (Sweden)

    F. G. Lovshenko

    2016-01-01

    Full Text Available The paper presents results of the investigations pertaining to creation of scientifically substantiated criteria for selection of alloying components and base compositions for manufacturing of mechanically alloyed dispersion-strengthened metallic materials. An analysis of dispersion strengthening mechanisms and regularities in mechanically activated phase and structural transformations serve as a reliable basis for solution of the assigned mission. Foer efficient strengthening at low and high temperatures as well materials must have fragmented and polygonized structure with maximum developed surface of grain and sub-grain boundaries which are stabilized by nano-sized inclusions of strengthening phases. Experimental investigations have shown that an optimum complex of mechanical properties is obtained in the case when nano-sized strengthening phase is equal to 3–5 % (volume. The phases applied for dispersion strengthening must have high value of shear modulus that determines their hardness and strength. Critical compressive stress should not cause deformation and destruction of disperse particles. Furthermore, they must have high stability in contact with a matrix. The substances applied as alloying components for realization of the developed technology on obtaining dispersion-strengthening materials must firstly meet the following requirements: they must be cheap, accessible and ecologically safety; they must interact with the basis or inter se at temperatures which are lower of material melting temperature; one of the phases which is formed in the process of the technology realization must have rather high thermodynamic stability and high value of the shear modulus; other formed phases must improve or, at the least, not reduce physical and mechanical properties of the materials. 

  15. Modelling of solidification processing and continuous strip casting for copper-base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoudi, Jafar [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Materials Processing

    2000-04-01

    An experimental and numerical study was carried out to investigate the solidification process in a copper continuous strip casting process. Heat flow and solidification process has been experimentally studied. Cooling curves during solidification were registered using a thermocouple of type K connected to a data acquisition system. Temperature measurements in the mould and cooling water were also performed. The numerical model considers a generalized set of mass, momentum and heat equations that is valid for the solid, liquid and solidification interval in the cast. A k-{epsilon} turbulence model, produced with the commercial program CFX, is used to analyse the solidification process of pure copper in the mould region of the caster. The fluid flow, temperature and heat flux distributions in the mould region of the caster were computed. The shape and location of the solidification front were also determined. The effects of the parameters such as heat transfer coefficient, casting speed, casting temperature, heat of fusion and specific heat on the shape and location of the solidification front and the heat transport at the mould-cast interface were investigated. The predicted temperature and heat flux distributions were compared with experimental measurements, and reasonable agreement was obtained. The solidification behaviour of pure copper and different copper base alloys has been studied. A series of solidification experiments using DTA furnace, mirror furnace and levitation technique were performed on different copper-base alloys. The undercooling, cooling rates of the liquid and the solid states, solidification times and temperatures were evaluated from the curves. The cooling curves for different samples were simulated using a FEM solidification program. It was found that the calculated values of the heat of fusion were much lower than the tabulated ones. The fraction of solid formed before quenching, in the DTA experiments, has been observed to be much higher

  16. Durability and degradation of HT9 based alloy waste forms with variable Ni and Cr content

    Energy Technology Data Exchange (ETDEWEB)

    Olson, L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-12-31

    Short-term electrochemical and long-term hybrid electrochemical corrosion tests were performed on alloy waste forms in reference aqueous solutions that bound postulated repository conditions. The alloy waste forms investigated represent candidate formulations that can be produced with advanced electrochemical treatment of used nuclear fuel. The studies helped to better understand the alloy waste form durability with differing concentrations of nickel and chromium, species that can be added to alloy waste forms to potentially increase their durability and decrease radionuclide release into the environment.

  17. Spectroscopic and mechanical studies on the Fe-based amorphous alloy 2605SA1

    Energy Technology Data Exchange (ETDEWEB)

    Cabral P, A.; Garcia S, I. [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Contreras V, J. A.; Garcia S, F. [Universidad Autonoma del Estado de Mexico, Facultad de Ciencias, El Cerrillo Piedras Blancas, Toluca, Estado de Mexico (Mexico); Nava, N., E-mail: agustin.cabral@inin.gob.m [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas No. 152, Col. San Bartolo Atepehuacan, 07730 Mexico D. F. (Mexico)

    2010-07-01

    The Vickers micro-hardness of this alloy was unusually dependent on the heat treatment from 300 to 634 K, inferring important micro-structural changes and the presence of amorphous grains before its phase transition. Once the alloy is crystallized, the micro-hardness is characteristic of a brittle alloy, the main problem of these alloys. Within the amorphous state, other properties like free-volume, magnetic states and Fe-Fe distances were followed by Positron annihilation lifetime spectroscopy and Moessbauer spectroscopy, respectively, to analyze those micro-structural changes, thermally induced, which are of paramount interest to understand their brittleness problem. (Author)

  18. Laser Clad ZrO2-Y2O3 Ceramic/Ni-base Alloy Composite Coatings

    NARCIS (Netherlands)

    Pei, Y.T.; Ouyang, J.H.; Lei, T.C.; Zhou, Y.

    1995-01-01

    A laser cladding technique was used to produce ZrO2-Y2O3 ceramic/Ni-base alloy composite coatings on stainless steel 4Cr13. The microstructure and hardness of the composite coatings are analyzed by XRD, SEM, EPMA, TEM and microhardness testing techniques. A stratification is observed in the laser

  19. Link between structural and mechanical stability of fcc- and bcc-based ordered MgeLi alloys

    CSIR Research Space (South Africa)

    Phasha, MJ

    2010-06-01

    Full Text Available properties of cubic-based MgeLi alloys. The heats of formation and elastic moduli were used in predicting structural stability profile, and their results are consistent with each other. In terms of phase stability, an interesting correlation between...

  20. Evaluation of mechanical properties of recasted dental base metal alloys for considering their reusability in dentistry and engineering field

    Directory of Open Access Journals (Sweden)

    Nandish Bantarahalli Thopegowda

    2014-01-01

    Full Text Available Background: Base metal casting alloys are extensively used in dentistry to fabricate many oral appliances and a huge amount is wasted in the form of sprues and buttons during the casting procedure. Recycling and reusing these alloys by clean technologies may save our natural resources from being depleted and as well reduce the cost of the treatment of the patients. Objectives: To study the mechanical properties of recasted dental base metal alloys, and explore possible ways to recycle and reuse in dentistry and other fields of science and technology. Materials and Methods: Two beryllium-free Cobalt-Chromium (Co-Cr dental casting alloys, Wironit and Wirobond-C, were used for this study. Six groups of specimen (melted once, twice, five, ten, fifteen and twenty times per each alloy were casted. The tensile strength and hardness of these samples were measured by using universal testing machine and Vickers hardness number (VHN tester. Results: Tensile strength decreased from 850 MPa to 777 MPa after 5 th recasting and to 674 MPa at the end of 20 th recasting procedure for the Wironit samples. For Wirobond-C samples, tensile strength decreased from 720 MPa to 678 MPa after 5 th recasting and further reduced to 534 MPa at the end of 20 th recasting procedure. Hardness decreased from 380VHN to 335VHN at the end of 20 th recasting for Wironit samples and 328VHN to 247VHN for Wirobond-C samples after 20 th recasting procedure. The slight decrease in their mechanical properties will not have any impact on the clinical performance for dental applications. Conclusion: There is no major degradation in the mechanical properties after recycling, and hence, the left over alloys after casting procedures can be reused in dentistry with a condition to satisfy cytotoxicity tests.

  1. The French regulatory experience and views on nickel-base alloy PWSCC prevention and treatment

    Energy Technology Data Exchange (ETDEWEB)

    Turluer, G.; Cattiaux, G.; Monnot, B. [Institut de Radioprotection et de Surete Nucleaire, IRSN, 92 - Fontenay aux Roses (France); Emond, D.; Reuchet, J.; Chartier, Ph. [Direction Generale de la Surete Nucleaire et de la Radioprotection, 75 - Paris (France)

    2003-10-01

    This paper presents the experience feedback and views of the French Regulatory Authority (ASN) and of the technical support institute (IRSN) on PWSCC prevention since the initiation in 1989 of the 'Inconel Zones Review' requested by ASN to Electricite de France (EDF), the national operator of a fleet of 58 PWRs. This proactive requirement, launched before the discovery, in September 1991, of the only CRDM nozzle leak in France, on Bugey unit 3, was then triggered by the recurrence of many alloy 600 rapid degradations and leaks, world wide, and also in France in the late 1980's, particularly on steam generator tubes and on some pressurizer penetrations. Thus, the ASN requested that EDF, perform a comprehensive (generic) proactive assessment on all the nickel-base alloy components and parts of the main primary circuits, which of course included vessel head penetrations and bottom vessel head penetrations, and some other zones as a first priority. This proactive 'review' did, a minima, include the following tasks and actions: - Update and complete, by an extensive R and D program, the understanding and characterization of the Ni base alloys prone to PWSCC, - Analyze the various materials, metallurgical features, mechanical stresses, and physicochemical conditions of the parts exposed to primary water, in order to predict the occurrence of PWSCC initiation and propagation, - Provide a prioritization of the zones to be inspected, - Implement by improved NDE techniques a practical inspection program on the 58 PWRs, - Prepare and implement any needed mitigation actions as a result of the components conditions assessment. The present paper relates the main features of the French regulatory experience over more than 13 years and recalls the main principles of the assessment, which were applied by ASN. These principles, which are formalized in the current regulation rules revised in 1999, are briefly listed hereunder: - It is based on avoiding and

  2. Biodegradable surgical implants based on magnesium alloys - A review of current research

    Energy Technology Data Exchange (ETDEWEB)

    Seal, C K; Hodgson, M A [School of Engineering, University of Auckland, 20 Symonds St., Auckland 1010 (New Zealand); Vince, K, E-mail: c.seal@auckland.ac.nz [Department of Orthopaedic Surgery, Level 7, Auckland City Hospital (New Zealand)

    2009-08-15

    There is considerable interest in the potential of magnesium alloys to be used in place of existing materials for surgical implants. Of particular interest is the possibility of using magnesium implants to act as both scaffolding on which new bone can grow, and as fixtures to hold together bone long enough to allow natural healing to take place. Magnesium is particularly desirable in this type of application as it is bio-compatible, and it has a modulus of elasticity closer to bone than currently used materials. Another major advantage of using magnesium as a surgical implant is in its ability to biodegrade in situ. This in turn means that the implant need not remain in the body without needing extra surgery to remove it. This paper presents a review of current research into magnesium based surgical implants.

  3. Energy-based fatigue model for shape memory alloys including thermomechanical coupling

    Science.gov (United States)

    Zhang, Yahui; Zhu, Jihong; Moumni, Ziad; Van Herpen, Alain; Zhang, Weihong

    2016-03-01

    This paper is aimed at developing a low cycle fatigue criterion for pseudoelastic shape memory alloys to take into account thermomechanical coupling. To this end, fatigue tests are carried out at different loading rates under strain control at room temperature using NiTi wires. Temperature distribution on the specimen is measured using a high speed thermal camera. Specimens are tested to failure and fatigue lifetimes of specimens are measured. Test results show that the fatigue lifetime is greatly influenced by the loading rate: as the strain rate increases, the fatigue lifetime decreases. Furthermore, it is shown that the fatigue cracks initiate when the stored energy inside the material reaches a critical value. An energy-based fatigue criterion is thus proposed as a function of the irreversible hysteresis energy of the stabilized cycle and the loading rate. Fatigue life is calculated using the proposed model. The experimental and computational results compare well.

  4. Processing and properties of Titanium alloy based materials with tailored porosity and composition

    Science.gov (United States)

    Cabezas-Villa, Jose Luis; Olmos, Luis; Lemus-Ruiz, Jose; Bouvard, Didier; Chavez, Jorge; Jimenez, Omar; Manuel Solorio, Victor

    2017-06-01

    This paper deals with powder processing of Ti6Al4V titanium alloy based materials with tailored porosity and composition. Ti6Al4V powder was mixed either with salt particles acting as space holder, so as to provide two-scale porosity, or with hard TiN particles that significantly modified the microstructure of the material and increased its hardness. Finally an original three-layer component was produced. Sample microstructure was observed by SEM and micro-tomography with special interest in pore size and shape, inclusion distribution and connectivity. Compression tests provided elastic modulus and yield stress as functions of density. These materials are representative of bone implants subjected to complex biological and mechanical conditions. These results thus open avenues for processing personalized implants by powder metallurgy.

  5. Green fluorescent genetically encoded calcium indicator based on calmodulin/M13-peptide from fungi.

    Directory of Open Access Journals (Sweden)

    Natalia V Barykina

    Full Text Available Currently available genetically encoded calcium indicators (GECIs utilize calmodulins (CaMs or troponin C from metazoa such as mammals, birds, and teleosts, as calcium-binding domains. The amino acid sequences of the metazoan calcium-binding domains are highly conserved, which may limit the range of the GECI key parameters and cause undesired interactions with the intracellular environment in mammalian cells. Here we have used fungi, evolutionary distinct organisms, to derive CaM and its binding partner domains and design new GECI with improved properties. We applied iterative rounds of molecular evolution to develop FGCaMP, a novel green calcium indicator. It includes the circularly permuted version of the enhanced green fluorescent protein (EGFP sandwiched between the fungal CaM and a fragment of CaM-dependent kinase. FGCaMP is an excitation-ratiometric indicator that has a positive and an inverted fluorescence response to calcium ions when excited at 488 and 405 nm, respectively. Compared with the GCaMP6s indicator in vitro, FGCaMP has a similar brightness at 488 nm excitation, 7-fold higher brightness at 405 nm excitation, and 1.3-fold faster calcium ion dissociation kinetics. Using site-directed mutagenesis, we generated variants of FGCaMP with improved binding affinity to calcium ions and increased the magnitude of FGCaMP fluorescence response to low calcium ion concentrations. Using FGCaMP, we have successfully visualized calcium transients in cultured mammalian cells. In contrast to the limited mobility of GCaMP6s and G-GECO1.2 indicators, FGCaMP exhibits practically 100% molecular mobility at physiological concentrations of calcium ion in mammalian cells, as determined by photobleaching experiments with fluorescence recovery. We have successfully monitored the calcium dynamics during spontaneous activity of neuronal cultures using FGCaMP and utilized whole-cell patch clamp recordings to further characterize its behavior in neurons

  6. Developement of calcium aluminate based systems for sludge cementation from radwaste decontamination

    OpenAIRE

    Martin, Isabelle

    2016-01-01

    Nuclear industry generated waste including radioactive wastes, which have different forms and origins. The wastes produced by reprocessing of nuclear fuel are characterized by important water content, by high pH and temperature sensitivity. The cementation in ettringite systems might be a promising solution to solidify radioactive wastes. Mixtures of Calcium Aluminate Cement (CAC) and calcium sulfate are planned to be used, instead of Ordinary Portland Cement (OPC), to form a significant amou...

  7. Fiber laser cladding of nickel-based alloy on cast iron

    Science.gov (United States)

    Arias-González, F.; del Val, J.; Comesaña, R.; Penide, J.; Lusquiños, F.; Quintero, F.; Riveiro, A.; Boutinguiza, M.; Pou, J.

    2016-06-01

    Gray cast iron is a ferrous alloy characterized by a carbon-rich phase in form of lamellar graphite in an iron matrix while ductile cast iron presents a carbon-rich phase in form of spheroidal graphite. Graphite presents a higher laser beam absorption than iron matrix and its morphology has also a strong influence on thermal conductivity of the material. The laser cladding process of cast iron is complicated by its heterogeneous microstructure which generates non-homogeneous thermal fields. In this research work, a comparison between different types of cast iron substrates (with different graphite morphology) has been carried out to analyze its impact on the process results. A fiber laser was used to generate a NiCrBSi coating over flat substrates of gray cast iron (EN-GJL-250) and nodular cast iron (EN-GJS-400-15). The relationship between processing parameters (laser irradiance and scanning speed) and geometry of a single laser track was examined. Moreover, microstructure and composition were studied by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and X-Ray Diffraction (XRD). The hardness and elastic modulus were analyzed by means of micro- and nanoindentation. A hardfacing coating was generated by fiber laser cladding. Suitable processing parameters to generate the Ni-based alloy coating were determined. For the same processing parameters, gray cast iron samples present higher dilution than cast iron samples. The elastic modulus is similar for the coating and the substrate, while the Ni-based coating obtained presents a significantly superior hardness than cast iron.

  8. Microstructural Characteristics and Tribological Behavior of HVOF-Sprayed Novel Fe-Based Alloy Coatings

    Directory of Open Access Journals (Sweden)

    Andrea Milanti

    2014-01-01

    Full Text Available Thermally-sprayed Fe-based coatings have shown their potential for use in wear applications due to their good tribological properties. In addition, these kinds of coatings have other advantages, e.g., cost efficiency and positive environmental aspects. In this study, the microstructural details and tribological performances of Fe-based coatings (Fe-Cr-Ni-B-C and Fe-Cr-Ni-B-Mo-C manufactured by High Velocity Oxygen Fuel (HVOF thermal spray process are evaluated. Traditional Ni-based (Ni-Cr-Fe-Si-B-C and hard-metal (WC-CoCr coatings were chosen as references. Microstructural investigation (field-emission scanning electron microscope FESEM and X-Ray diffractometry XRD reveals a high density and low oxide content for HVOF Fe-based coatings. Particle melting and rapid solidification resulted in a metastable austenitic phase with precipitates of mixed carbides and borides of chromium and iron which lead to remarkably high nanohardness. Tribological performances were evaluated by means of the ball on-disk dry sliding wear test, the rubber-wheel dry particle abrasion test, and the cavitation erosion wear test. A higher wear resistance validates Fe-based coatings as a future alternative to the more expensive and less environmentally friendly Ni-based alloys.

  9. Bioactivity and biomineralization ability of calcium silicate-based pulp-capping materials after subcutaneous implantation.

    Science.gov (United States)

    Hinata, G; Yoshiba, K; Han, L; Edanami, N; Yoshiba, N; Okiji, T

    2017-06-26

    To evaluate the abilities of three calcium silicate-based pulp-capping materials (ProRoot MTA, TheraCal LC and a prototype tricalcium silicate cement) to produce apatite-like precipitates after being subcutaneously implanted into rats. Polytetrafluoroethylene tubes containing each material were subcutaneously implanted into the backs of Wistar rats. At 7, 14 and 28 days post-implantation, the implants were removed together with the surrounding connective tissue, and fixed in 2.5% glutaraldehyde in cacodylate buffer. The chemical compositions of the surface precipitates formed on the implants were analysed with scanning electron microscopy-electron probe microanalysis (SEM-EPMA). The distributions of calcium (Ca) and phosphorus (P) at the material-tissue interface were also analysed with SEM-EPMA. Comparisons of the thicknesses of the Ca- and P-rich areas were performed using the Friedman test followed by Scheffe's test at a significant level of 5%. All three materials produced apatite-like surface precipitates containing Ca and P. For each material, elemental mapping detected a region of connective tissue in which the concentrations of Ca and P were higher than those in the surrounding connective tissue. The thickness of this Ca- and P-rich region exhibited the following pattern: ProRoot MTA > prototype tricalcium silicate cement ≥ TheraCal LC. ProRoot MTA had a significantly thicker layer of Ca and P than the other materials at all time-points (P < 0.05), and a significant difference was detected between the prototype cement and TheraCal LC at 28 days (P < 0.05). After being subcutaneously implanted, all of the materials produced Ca- and P-containing surface precipitates and a Ca- and P-rich layer within the surrounding tissue. The thickness of the Ca- and P-rich layer of ProRoot MTA was significantly thicker than that of the other materials. © 2017 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  10. Effect of Different Irrigation Solutions on the Colour Stability of Three Calcium Silicate-Based Materials

    Directory of Open Access Journals (Sweden)

    Sobhnamayan F

    2017-06-01

    Full Text Available Abstract: Statement of Problem: Previous studies have shown discoloration of mineral trioxide aggregate (MTA in contact with root canal irrigation solutions. However, there are limited data on colour stability of other calcium silicate–based materials (CSMs. Objectives: This in vitro study aimed to evaluate the colour stability of three CSMs in contact with different irrigation solutions. Materials and Methods: Three CSMs including White MTA (wMTA Angelus, calcium enriched mixture (CEM, and Biodentine were assessed in this study. Forty five samples of each material were mixed according to the manufactures’ instructions and then placed in silicone tubes. After 24 hours, the materials were removed from the moulds and 9 samples of each material left dry or immersed in normal saline, 5% sodium hypochlorite (NaOCL, 2% chlorhexidinegluconate (CHX, or 17%EDTA for 24 hours. Colour changes were measured with a spectrophotometer. Data were evaluated with 2-way analysis of variance, one way analysis of variance and Tukey post hoc tests. Results: The highest discoloration of all materials was observed after contact with CHX. In the MTA Angelus and CEM cement groups, significant differences were observed between CHX and NaOCl and also between these two irrigants with the other three irrigants (p < 0.05. In the Biodentine group, CHX created statistically significant discoloration compared to other irrigants (p < 0.05. Only wMTA Angelus showed a significantly higher discoloration in contact with EDTA compared to normal saline and dry condition (p < 0.05. wMTA Angelus showed a significantly higher colour change compared with CEM cement and Biodentine after contact with NaOCl, CHX, and EDTA (p < 0.05. Conclusions: The contact of wMTA, CEM cement, and Biodentine with CHX should be avoided because this leads to severe discoloration. Contact with sodium hypochlorite also leads to discoloration of wMTA and CEM cements. Among of the three tested materials, w

  11. New concept of composite strengthening in Co-Re based alloys for high temperature applications in gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Mukherji, D.; Roesler, J.; Fricke, T.; Schmitz, F. [Technische Univ. Braunschweig (DE). Inst. fuer Werkstoffkunde (IfW); Piegert, S. [Siemens AG, Berlin (DE). Energy Sector (F PR GT EN)

    2010-07-01

    High temperature material development is mainly driven by gas turbine needs. Today, Ni-based superalloys are the dominant material class in the hot section of turbines. Material development will continue to push the maximum service temperature of Ni-superalloys upwards. However, this approach has a fundamental limit and can not be sustained indefinitely, as the Ni-superalloys are already used very close to their melting point. Within the frame work of a DFG Forschergruppe program (FOR 727) - ''Beyond Ni-base Superalloys'' - Co-Re based alloys are being developed as a new generation of high temperature materials that can be used at +100 C above single crystal Ni-superalloys. Along with other strengthening concepts, hardening by second phase is explored to develop a two phase composite alloy. With quaternary Co-Re-Cr-Ni alloys we demonstrate this development concept, where Co{sub 2}Re{sub 3}-type {sigma} phase is used in a novel way as the hardening phase. Thermodynamic calculation was used for designing model alloy compositions. (orig.)

  12. Circular permutated red fluorescent proteins and calcium ion indicators based on mCherry.

    Science.gov (United States)

    Carlson, Haley J; Campbell, Robert E

    2013-12-01

    Red fluorescent indicators for calcium ion (Ca(2+)) are preferable, relative to blue-shifted alternatives, for biological imaging applications due to the lower phototoxicity, lower autofluorescent background and deeper tissue penetration associated with longer wavelength light. Accordingly, we undertook the development of a genetically encoded Ca(2+) indicator based on the popular and widely utilized Discosoma-derived red fluorescent protein, mCherry. Starting from a promising but dimly fluorescent circular permutated variant of mCherry, we first engineered a 13-fold brighter variant (cp196V1.2) through directed evolution. This bright cp196V1.2 was then used as the scaffold for creation of eight distinct libraries of potential Ca(2+) indicators via permutation at different sites within the 7th and 10th β-strands, and fusion of calmodulin and M13 to the new termini. Screening of these libraries led to the conclusion that, consistent with previous investigations of homologous fluorescent proteins, the 146-145 site in β-strand 7 is the most promising permutation site for construction of useful Ca(2+) indicators. Further rounds of directed evolution ultimately led to an indicator that exhibits a 250% change in intrinsic brightness in response to Ca(2+) and an exceptionally high affinity (Kd = 6 nM) for Ca(2+).

  13. Self-assembling of calcium salt of the new DNA base 5-carboxylcytosine

    Science.gov (United States)

    Irrera, Simona; Ruiz-Hernandez, Sergio E.; Reggente, Melania; Passeri, Daniele; Natali, Marco; Gala, Fabrizio; Zollo, Giuseppe; Rossi, Marco; Portalone, Gustavo

    2017-06-01

    Supramolecular architectures involving DNA bases can have a strong impact in several fields such as nanomedicine and nanodevice manufacturing. To date, in addition to the four canonical nucleobases (adenine, thymine, guanine and cytosine), four other forms of cytosine modified at the 5 position have been identified in DNA. Among these four new cytosine derivatives, 5-carboxylcytosine has been recently discovered in mammalian stem cell DNA, and proposed as the final product of the oxidative epigenetic demethylation pathway on the 5 position of cytosine. In this work, a calcium salt of 5-carboxylcytosine has been synthesized and deposited on graphite surface, where it forms self-assembled features as long range monolayers and up to one micron long filaments. These structures have been analyzed in details combining different theoretical and experimental approaches: X-ray single-crystal diffraction data were used to simulate the molecule-graphite interaction, first using molecular dynamics and then refining the results using density functional theory (DFT); finally, data obtained with DFT were used to rationalize atomic force microscopy (AFM) results.

  14. Biocompatibility of three new calcium silicate-based endodontic sealers on human periodontal ligament stem cells.

    Science.gov (United States)

    Collado-González, M; García-Bernal, D; Oñate-Sánchez, R E; Ortolani-Seltenerich, P S; Lozano, A; Forner, L; Llena, C; Rodríguez-Lozano, F J

    2017-09-01

    To evaluate the biocompatibility of three calcium silicate-based endodontic sealers, Bioroot BC Sealer (Septodont, Saint-Maur-des-Fosses, France), Endoseal MTA (EndoSeal, Maruchi, Seoul, Korea) and Nano-ceramic Sealer (B&L Biotech, Fairfax, VA, USA) (NCS), on human periodontal ligament stem cells (hPDLSCs). Human periodontal ligament stem cells were cultured in the presence of various endodontic sealer eluates for 24 h. Cell viability was determined using the MTT assay. Cell death and changes in phenotype induced by the set endodontic sealer eluates were evaluated through flow cytometry. Also, an in vitro scratch wound-healing model was used to determine their effects in cell migration. Finally, to assess cell morphology and attachment to the different sealers, hPDLSCs were directly seeded onto the material surfaces and analysed by scanning electron microscopy (SEM). One-way analysis of variance (anova) followed by a Bonferroni post-test was performed (P endodontic sealers for clinical application. © 2016 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  15. Self-assembling of calcium salt of the new DNA base 5-carboxylcytosine

    Energy Technology Data Exchange (ETDEWEB)

    Irrera, Simona [Department of Chemistry, SAPIENZA University of Rome, Piazzale A. Moro 5, 00185 Rome (Italy); Department of Chemistry, University College London, 20 Grodon Street, WC1H0AJ London (United Kingdom); Ruiz-Hernandez, Sergio E. [School of Chemistry, Cardiff University Main Building, Park Place, CF103AT Cardiff (United Kingdom); Reggente, Melania [Department of Basic and Applied Sciences for Engineering, SAPIENZA University of Rome, Via A. Scarpa 16, 00161 Rome (Italy); Passeri, Daniele, E-mail: daniele.passeri@uniroma1.it [Department of Basic and Applied Sciences for Engineering, SAPIENZA University of Rome, Via A. Scarpa 16, 00161 Rome (Italy); Natali, Marco [Department of Basic and Applied Sciences for Engineering, SAPIENZA University of Rome, Via A. Scarpa 16, 00161 Rome (Italy); Gala, Fabrizio [Department of Basic and Applied Sciences for Engineering, SAPIENZA University of Rome, Via A. Scarpa 16, 00161 Rome (Italy); Department of Medical-Surgical, Techno-Biomedical Sciences and Translational Medicine of SAPIENZA University of Rome, Sant’Andrea Hospital, Rome (Italy); Zollo, Giuseppe [Department of Basic and Applied Sciences for Engineering, SAPIENZA University of Rome, Via A. Scarpa 16, 00161 Rome (Italy); Rossi, Marco [Department of Basic and Applied Sciences for Engineering, SAPIENZA University of Rome, Via A. Scarpa 16, 00161 Rome (Italy); Research Center for Nanotechnology applied to Engineering of SAPIENZA University of Rome (CNIS), Piazzale A. Moro 5, 00185 Rome (Italy); Portalone, Gustavo, E-mail: gustavo.portalone@uniroma1.it [Department of Chemistry, SAPIENZA University of Rome, Piazzale A. Moro 5, 00185 Rome (Italy)

    2017-06-15

    Highlights: • Ca salt of 5-carboxylcytosine has been deposited on HOPG substrate. • Molecules self-assembled in monolayers and filaments. • Height of the features were measured by atomic force microscopy. • Ab-initio calculations confirmed the AFM results. - Abstract: Supramolecular architectures involving DNA bases can have a strong impact in several fields such as nanomedicine and nanodevice manufacturing. To date, in addition to the four canonical nucleobases (adenine, thymine, guanine and cytosine), four other forms of cytosine modified at the 5 position have been identified in DNA. Among these four new cytosine derivatives, 5-carboxylcytosine has been recently discovered in mammalian stem cell DNA, and proposed as the final product of the oxidative epigenetic demethylation pathway on the 5 position of cytosine. In this work, a calcium salt of 5-carboxylcytosine has been synthesized and deposited on graphite surface, where it forms self-assembled features as long range monolayers and up to one micron long filaments. These structures have been analyzed in details combining different theoretical and experimental approaches: X-ray single-crystal diffraction data were used to simulate the molecule-graphite interaction, first using molecular dynamics and then refining the results using density functional theory (DFT); finally, data obtained with DFT were used to rationalize atomic force microscopy (AFM) results.

  16. A novel hybrid multichannel biphasic calcium phosphate granule-based composite scaffold for cartilage tissue regeneration.

    Science.gov (United States)

    Jung, Albert; Makkar, Preeti; Amirian, Jhaleh; Lee, Byong-Taek

    2018-01-01

    The objective of the present study was to develop a novel hybrid multichannel biphasic calcium phosphate granule (MCG)-based composite system for cartilage regeneration. First, hyaluronic acid-gelatin (HG) hydrogel was coated onto MCG matrix (MCG-HG). Poly(lactic-co-glycolic acid) (PLGA) microspheres was separately prepared and modified with polydopamine subsequent to BMP-7 loading (B). The surface-modified microspheres were finally embedded into MCG-HG scaffold to develop the novel hybrid (MCG-HG-PLGA-PD-B) composite system. The newly developed MCG-HG-PLGA-PD-B composite was then subjected to scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier Transform infrared spectroscopy, porosity, compressive strength, swelling, BMP-7 release and in-vitro biocompatibility studies. Results showed that 60% of BMP-7 retained on the granular surface after 28 days. A hybrid MCG-HG-PLGA-PD-B composite scaffold exhibited higher swelling and compressive strength compared to MCG-HG or MCG. In-vitro studies showed that MCG-HG-PLGA-PD-B had improved cell viability and cell proliferation for both MC3T3-E1 pre-osteoblasts and ATDC5 pre-chondrocytes cell line with respect to MCG-HG or MCG scaffold. Our results suggest that a hybrid MCG-HG-PLGA-PD-B composite scaffold can be a promising candidate for cartilage regeneration applications.

  17. [Effect of gilding technique on the release of elements from copper-based alloy post-core].

    Science.gov (United States)

    Pan, Lu; Chen, Xin-min; Niu, Lin; Zhang, Shan-chuan

    2007-07-01

    To evaluate the effect of gilding technique on the release of element from copper-based alloy post-core exposed to artificial saliva. The quantities of nickel ion and copper ion released from common copper-based alloy post-core (control group), blasting gilding copper-based alloy post-core (blasting group) and burnishing gilding Copper-based alloy post-core (burnishing group) in artificial saliva after 1 month,3 months,6 months and 8 months of exposure were measured with atomic absorption spectrophotometer. The tooth tissues were stripped off at the eighth month and the oxygenization on the surface of the posts were observed. There was a significant difference of element release of nickel between the gilding groups and the control group at the sixth and eighth month. There was a significant difference of element release of copper between the gilding groups and the control group at the third, sixth and eighth month. The quantities of element released from the gilding groups were fewer than those from the control groups. The release of nickel and copper ions increased with the length of exposure significantly after three month of exposure. The element release from the control groups increased more rapidly than the gilding groups. The surface of the post-core in the control groups were all oxygenized while those in the gilding groups had been oxygenized only near the margins of the cores and the upper 1/3 part of the post with uncontinuous and relatively thin layers. Gilding surface treatment can decrease the release of nickel and copper ions from copper based-alloy post-core and the surface oxygenization, which will improve the biocompatibility of the core.

  18. Electrochemical Surface Treatment of a β-titanium Alloy to Realize an Antibacterial Property and Bioactivity

    Directory of Open Access Journals (Sweden)

    Yusuke Tsutsumi

    2016-03-01

    Full Text Available In this study, micro-arc oxidation (MAO was performed on a β-type titanium alloy, namely, Ti-29Nb-13Ta-4.6Zr alloy (TNTZ, to improve not only its antibacterial property but also bioactivity in body fluids. The surface oxide layer formed on TNTZ by MAO treatment in a mixture of calcium glycerophosphate, calcium acetate, and silver nitrate was characterized using surface analyses. The resulting porous oxide layer was mainly composed of titanium oxide, and it also contained calcium, phosphorus, and a small amount of silver, all of which were incorporated from the electrolyte during the treatment. The MAO-treated TNTZ showed a strong inhibition effect on anaerobic Gram-negative bacteria when the electrolyte contained more than 0.5 mM silver ions. The formation of calcium phosphate on the surface of the specimens after immersion in Hanks’ solution was evaluated to determine the bioactivity of TNTZ with sufficient antibacterial property. As a result, thick calcium phosphate layers formed on the TNTZ specimen that underwent MAO treatment, whereas no precipitate was observed on TNTZ without treatment. Thus, the MAO treatment of titanium-based alloys is confirmed to be effective in realizing both antibacterial and bioactive properties.

  19. Preliminary Analysis of the General Performance and Mechanical Behavior of Irradiated FeCrAl Base Alloys and Weldments

    Energy Technology Data Exchange (ETDEWEB)

    Gussev, Maxim N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Field, Kevin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Briggs, Samuel A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-09-30

    The iron-based, iron-chromium-aluminum (FeCrAl) alloys are promising, robust materials for deployment in current and future nuclear power plants. This class of alloys demonstrates excellent performance in a range of environments and conditions, including high-temperature steam (>1000°C). Furthermore, these alloys have the potential to have prolonged survival under loss-of-coolant accident (LOCA) conditions compared to the more traditional cladding materials that are either Zr-based alloys or austenitic steels. However, one of the issues associated with FeCrAl alloys is cracking during welding. The present project investigates the possibility of mitigating welding-induced cracking via alloying and precise structure control of the weldments; in the frame work of the project, several advanced alloys were developed and are being investigated prior to and after neutron irradiation to provide insight into the radiation tolerance and mechanical performance of the weldments. The present report provides preliminary results on the post-irradiation characterization and mechanical tests performed during United States Fiscal Year (FY) 2016. Chapter 1 provides a general introduction, and Chapter 2 describes the alloy compositions, welding procedure, specimen geometry and manufacturing parameters. Also, a brief discussion of the irradiation at the High Flux Isotope Reactor (HFIR) is provided. Chapter 3 is devoted to the analysis of mechanical tests performed at the hot cell facility; tensile curves and mechanical properties are discussed in detail focusing on the irradiation temperature. Limited fractography results are also presented and analyzed. The discussion highlights the limitations of the testing within a hot cell. Chapter 4 underlines the advantages of in-situ testing and discusses the preliminary results obtained with newly developed miniature specimens. Specimens were moved to the Low Activation Materials Development and Analysis (LAMDA) laboratory and prepared for

  20. Negative interferences by calcium dobesilate in the detection of five serum analytes involving Trinder reaction-based assays.

    Science.gov (United States)

    Guo, Xiuzhi; Hou, Li'an; Yin, Yicong; Wu, Jie; Zhao, Fang; Xia, Liangyu; Cheng, Xinqi; Liu, Qian; Liu, Li; Xu, Ermu; Qiu, Ling

    2018-01-01

    Previously, we reported the strong negative interference of calcium dobesilate, a vasoprotective agent, in creatinine assays involving the Trinder reaction. It is hypothesized that a similar effect occurs in the detection of uric acid (UA), total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C). The interferences of calcium dobesilate during the detection of the five serum analytes were investigated on automated systems/analysers, and the effects were compared among eight different assay systems for each analyte. A calcium dobesilate standard was added into two sets of the blank serum pools of each analyte at final concentrations of 0, 2, 4, 8, 16, 32, and 64 μg/mL. The percentage deviation of each analyte value was calculated between each drug concentration and the drug-free samples. The clinically acceptable error levels for UA, TC, TG, HDL-C, and LDL-C were defined as ±4.87%, ±4.1%, ±9.57%, ±5.61%, and ±5.46%, respectively. The observed interference was concentration dependent for each analyte. In the presence of 16 μg/mL calcium dobesilate, which was within the therapeutic range, all seven Trinder reaction-based UA assay systems, two TG assay systems, two HDL-C assay systems and one TC assay system exhibited negative drug interferences. Calcium dobesilate negatively interferes with the detection of UA, TG, TC, and HDL-C in assay systems based on the Trinder reaction. The effect was most significant in UA and TG detection.

  1. An investigation on the rheological and sulfur-retention characteristics of desulfurizing coal water slurry with calcium-based additives

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jianzhong; Zhao, Weidong; Zhou, Junhu; Cheng, Jun; Zhang, Guangxue; Feng, Yungang; Cen, Kefa [State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027 (China)

    2009-01-15

    Desulphurizing coal water slurry is a kind of new clean coal water slurry(CWS), which has good performance on SO{sub 2} emission during combustion and gasification process. But, the addition of sulfur-retention agents have some effects on the stability and fluid characters of the coal water slurry. In this paper, the viscosity, stability and rheology of Xinwen coal water slurry have been studied by adding different kinds of calcium-based sulfur-retention agents and different dosage. The results show that the sulfur-retention agents have little effect on rheological nature of CWS, which still presents pseudoplastic fluid. The addition of sulfur-retention agents will increase the viscosity of CWS, but the stability will decrease a little. The results also show that inorganic calcium has less negative effect on the performance of CWS than the organic calcium. The viscosity of the CWS with organic calcium agent keeps 1000-1200 mPa s when Ca/S molar ratio is 2. Sulfur release of the CWS with CaCO{sub 3} reduces to 52% at Ca/S = 2 compared to original of 98%. (author)

  2. A Comparative Chemical Study of Calcium Silicate-Containing and Epoxy Resin-Based Root Canal Sealers

    Directory of Open Access Journals (Sweden)

    Przemysław Reszka

    2016-01-01

    Full Text Available Objective. The present study assessed the chemical elements in two novel calcium silicate-containing root canal sealers, BioRoot RCS and Well-Root ST, compared to a calcium silicate-containing root canal sealer that has been on the market for several years, MTA Fillapex, and epoxy resin-based sealer AHPlus. Material and Methods. The sealers were mixed and manipulated according to the manufacturers’ instructions. Twelve cylindrical molds (inner diameter 4 mm; height 3 mm were placed on a glass petri dish and packed with the materials. The dish was transferred to an incubator. After 72 h the molds were examined by scanning electron microscopy and energy dispersive X-ray microanalysis. Results. BioRoot RCS and Well-Root ST had high peaks of calcium, zirconium, oxygen, carbon, silicon, and chlorine. Well-Root ST also had sodium, magnesium, aluminum, and titanium peaks. MTA Fillapex and AHPlus had carbon, oxygen, calcium, titanium, and bismuth peaks. A silicon peak was also observed for MTA Fillapex, and zirconium and tungsten peaks for AHPlus. Conclusion. BioRoot RSC had the highest degree of purity. The clinical implication of metals contained in the other sealers needs to be investigated.

  3. A Comparative Chemical Study of Calcium Silicate-Containing and Epoxy Resin-Based Root Canal Sealers.

    Science.gov (United States)

    Reszka, Przemysław; Nowicka, Alicja; Lipski, Mariusz; Dura, Włodzimierz; Droździk, Agnieszka; Woźniak, Krzysztof

    2016-01-01

    Objective. The present study assessed the chemical elements in two novel calcium silicate-containing root canal sealers, BioRoot RCS and Well-Root ST, compared to a calcium silicate-containing root canal sealer that has been on the market for several years, MTA Fillapex, and epoxy resin-based sealer AHPlus. Material and Methods. The sealers were mixed and manipulated according to the manufacturers' instructions. Twelve cylindrical molds (inner diameter 4 mm; height 3 mm) were placed on a glass petri dish and packed with the materials. The dish was transferred to an incubator. After 72 h the molds were examined by scanning electron microscopy and energy dispersive X-ray microanalysis. Results. BioRoot RCS and Well-Root ST had high peaks of calcium, zirconium, oxygen, carbon, silicon, and chlorine. Well-Root ST also had sodium, magnesium, aluminum, and titanium peaks. MTA Fillapex and AHPlus had carbon, oxygen, calcium, titanium, and bismuth peaks. A silicon peak was also observed for MTA Fillapex, and zirconium and tungsten peaks for AHPlus. Conclusion. BioRoot RSC had the highest degree of purity. The clinical implication of metals contained in the other sealers needs to be investigated.

  4. Effect of Co content on structure and magnetic behaviors of high induction Fe-based amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Rajat K., E-mail: rajat@nmlindia.org; Panda, Ashis K.; Mitra, Amitava

    2016-11-15

    The replacement of Fe with Co is investigated in the (Fe{sub 1−x}Co{sub x}){sub 79}Si{sub 8.5}B{sub 8.5}Nb{sub 3}Cu{sub 1} (x=0, 0.05, 0.2, 0.35, 0.5) amorphous alloys. The alloys are synthesized in the forms of ribbons by single roller melt spinning technique, and the structural and magnetic properties of annealed ribbons are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM), B–H curve tracer, respectively. All as-cast alloys are structurally amorphous, however, their magnetic properties are varying with Co addition. The Co addition within 5–20 at% results in moderate thermal stability, saturation induction, Curie temperature and lowest coercivity, while 35 at% Co causes highest saturation induction, coercivity, Curie temperature and lowest thermal stability. On devitrification, the magnetic properties change with the generation of α-FeCo nanocrystallites and (FeCo){sub 23}B{sub 6}, Fe{sub 2}B phases during primary and secondary crystallization stages, respectively. A small amount Co is advantageous for maintaining finer nanocrystallites in amorphous matrix even after annealing at 600 °C, leading to high saturation magnetization (>1.5 T) and low coercivity (~35 A/m). The improved magnetic properties at elevated temperatures indicate these alloys have a potential for high frequency transformer core applications. - Highlights: • The structural and magnetic behaviors of Fe based amorphous alloys have been investigated with the effect of Co content. • The Co has no adverse effect on amorphization of alloys. • A small amount Co causes the superior improvement of magnetic properties at elevated temperatures. • Therefore, it is important not only for academic research but also for industrial applied research.

  5. Biocalcite, a multifunctional inorganic polymer: Building block for calcareous sponge spicules and bioseed for the synthesis of calcium phosphate-based bone

    Directory of Open Access Journals (Sweden)

    Xiaohong Wang

    2014-05-01

    Full Text Available Calcium carbonate is the material that builds up the spicules of the calcareous sponges. Recent results revealed that the calcium carbonate/biocalcite-based spicular skeleton of these animals is formed through an enzymatic mechanism, such as the skeleton of the siliceous sponges, evolutionarily the oldest animals that consist of biosilica. The enzyme that mediates the calcium carbonate deposition has been identified as a carbonic anhydrase (CA and has been cloned from the calcareous sponge species Sycon raphanus. Calcium carbonate deposits are also found in vertebrate bones besides the main constituent, calcium phosphate/hydroxyapatite (HA. Evidence has been presented that during the initial phase of HA synthesis poorly crystalline carbonated apatite is deposited. Recent data summarized here indicate that during early bone formation calcium carbonate deposits enzymatically formed by CA, act as potential bioseeds for the precipitation of calcium phosphate mineral onto bone-forming osteoblasts. Two different calcium carbonate phases have been found during CA-driven enzymatic calcium carbonate deposition in in vitro assays: calcite crystals and round-shaped vaterite deposits. The CA provides a new target of potential anabolic agents for treatment of bone diseases; a first CA activator stimulating the CA-driven calcium carbonate deposition has been identified. In addition, the CA-driven calcium carbonate crystal formation can be frozen at the vaterite state in the presence of silintaphin-2, an aspartic acid/glutamic acid-rich sponge-specific protein. The discovery that calcium carbonate crystals act as bioseeds in human bone formation may allow the development of novel biomimetic scaffolds for bone tissue engineering. Na-alginate hydrogels, enriched with biosilica, have recently been demonstrated as a suitable matrix to embed bone forming cells for rapid prototyping bioprinting/3D cell printing applications.

  6. In situ Raman spectroscopic analysis of surface oxide films on Ni-base alloy/low alloy steel dissimilar metal weld interfaces in high-temperature water

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jongjin; Choi, Kyung Joon [School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology (UNIST), 100 Banyeon-ri, Eonyang-eup, Ulju-gun, Ulsan 689-798 (Korea, Republic of); Bahn, Chi Bum [School of Mechanical Engineering, Pusan National University 2, 63-gil, Geumjeong-Gu, Pusan 609-735 (Korea, Republic of); Kim, Ji Hyun, E-mail: kimjh@unist.ac.kr [School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology (UNIST), 100 Banyeon-ri, Eonyang-eup, Ulju-gun, Ulsan 689-798 (Korea, Republic of)

    2014-06-01

    In situ Raman spectroscopy has been applied to analyze the surface oxide films formed on dissimilar metal weld (DMW) interfaces of nickel-base alloy/low alloy steel under hydrogenated high-temperature water condition. For the analysis of the oxide films under high temperature/pressure aqueous conditions, an in situ Raman spectroscopy system was developed by constructing a hydrothermal cell where the entire optics including the excitation laser and the Raman light collection system were located at the nearest position to the specimen by means of immersion optics. In situ Raman spectra of the DMW interfaces were collected in hydrogenated water condition at different temperatures up to 300 °C. The measured in situ Raman spectra showed peaks of Cr{sub 2}O{sub 3}, NiCr{sub 2}O{sub 4} and Fe{sub 3}O{sub 4} at the DMW interface. It is considered that differences in the oxide chemistry originated from the chemical element distribution inside of the DMW interface region.

  7. Neutronics Evaluation of Lithium-Based Ternary Alloys in IFE Blankets

    Energy Technology Data Exchange (ETDEWEB)

    Jolodosky, A. [Univ. of California, Berkeley, CA (United States); Fratoni, M. [Univ. of California, Berkeley, CA (United States)

    2015-09-22

    , low electrical conductivity and therefore low MHD pressure drop, low chemical reactivity, and extremely low tritium inventory; the addition of sodium (FLiNaBe) has been considered because it retains the properties of FliBe but also lowers the melting point. Although many of these blanket concepts are promising, challenges still remain. The limited amount of beryllium available poses a problem for ceramic breeders such as the HCPB. FLiBe and FLiNaBe are highly viscous and have a low thermal conductivity. Lithium lead possesses a poor thermal conductivity which can cause problems in both DCLL and LiPb blankets. Additionally, the tritium permeation from these two blankets into plant components can be a problem and must be reduced. Consequently, Lawrence Livermore National Laboratory (LLNL) is attempting to develop a lithium-based alloy—most likely a ternary alloy—which maintains the beneficial properties of lithium (e.g. high tritium breeding and solubility) while reducing overall flammability concerns for use in the blanket of an inertial fusion energy (IFE) power plant. The LLNL concept employs inertial confinement fusion (ICF) through the use of lasers aimed at an indirect-driven target composed of deuterium-tritium fuel. The fusion driver/target design implements the same physics currently experimented at the National Ignition Facility (NIF). The plant uses lithium in both the primary coolant and blanket; therefore, lithium-related hazards are of primary concern. Although reducing chemical reactivity is the primary motivation for the development of new lithium alloys, the successful candidates will have to guarantee acceptable performance in all their functions. The scope of this study is to evaluate the neutronics performance of a large number of lithium-based alloys in the blanket of the IFE engine and assess their properties upon activation. This manuscript is organized as follows: Section 12 presents the models and methodologies used for the analysis; Section

  8. Elastoplastic properties of a low-modulus titanium-based β alloy

    Science.gov (United States)

    Betekhtin, V. I.; Kolobov, Yu. R.; Golosova, O. A.; Kardashev, B. K.; Kadomtsev, A. G.; Narykova, M. V.; Ivanov, M. B.; Vershinina, T. N.

    2013-10-01

    The elastoplastic properties (elastic modulus, amplitude-independent damping ratio, microplastic flow stress) of a Ti-26Nb-7Mo-12Zr titanium β alloy are determined using an acoustic resonance method. The effect of the strain during thermomechanical treatment on the structural features of the micro-crystalline alloy and, hence, its elastoplastic properties is analyzed.

  9. Compositional modification of Ni-base alloys for laser-deposition technologies

    NARCIS (Netherlands)

    Hemmati, I.; Ocelík, V.; De Hosson, J. Th M.

    2014-01-01

    Cracking of the clad layers is a major issue in laser cladding of hard wear-resistant coatings such as Ni-Cr-B-Si-C alloys. One way to solve this problem is to increase the toughness of these alloys by compositional and microstructural modifications. The focus of this chapter is on defining a

  10. Effect of preconditioning cobalt and nickel based dental alloys with Bacillus sp. extract on their surface physicochemical properties and theoretical prediction of Candida albicans adhesion.

    Science.gov (United States)

    Balouiri, Mounyr; Bouhdid, Samira; Sadiki, Moulay; Ouedrhiri, Wessal; Barkai, Hassan; El Farricha, Omar; Ibnsouda, Saad Koraichi; Harki, El Houssaine

    2017-02-01

    Biofilm formation on dental biomaterials is implicated in various oral health problems. Thus the challenge is to prevent the formation of this consortium of microorganisms using a safe approach such as antimicrobial and anti-adhesive natural products. Indeed, in the present study, the effects of an antifungal extract of Bacillus sp., isolated from plant rhizosphere, on the surface physicochemical properties of cobalt and nickel based dental alloys were studied using the contact angle measurements. Furthermore, in order to predict the adhesion of Candida albicans to the treated and untreated dental alloys, the total free energy of adhesion was calculated based on the extended Derjaguin-Landau-Verwey-Overbeek approach. Results showed hydrophobic and weak electron-donor and electron-acceptor characteristics of both untreated dental alloys. After treatment with the antifungal extract, the surface free energy of both dental alloys was influenced significantly, mostly for cobalt based alloy. In fact, treated cobalt based alloy became hydrophilic and predominantly electron donating. Those effects were time-dependent. Consequently, the total free energy of adhesion of C. albicans to this alloy became unfavorable after treatment with the investigated microbial extract. A linear relationship between the electron-donor property and the total free energy of adhesion has been found for both dental alloys. Also, a linear relationship has been found between this latter and the hydrophobicity for the cobalt based alloy. However, the exposure of nickel based alloy to the antifungal extract failed to produce the same effect. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Parametric Study on the Tensile Properties of Ni-Based Alloy for a VHTR

    Science.gov (United States)

    Kim, Dong-Jin; Jung, Su Jin; Mun, Byung Hak; Kim, Sung Woo; Lim, Yun Soo

    2015-01-01

    A very high-temperature reactor (VHTR) has been studied among generation IV nuclear power plants owing to its many advantages such as high-electric efficiency and massive hydrogen production. The material used for the heat exchanger should sustain structural integrity for its life even though the material is exposed to a harsh environment at 1223 K (950 °C) in an impure helium coolant. Therefore, an enhancement of the material performance at high temperature gives a margin in determining the operating temperature and life time. This work is an effort to find an optimum combination of alloying elements and processing parameters to improve the material performance. The tensile property and microstructure for nickel-based alloys fabricated in a laboratory were evaluated as a function of the heat treatment, cold working, and grain boundary strengthener using a tension test at 1223 K (950 °C), scanning electron microscopy, and transmission electron microscopy. Elongation to rupture was increased by additional heat treatment and cold working, followed by additional heat treatment in the temperature range from 1293 K to 1383 K (1020 °C to 1110 °C) implying that the intergranular carbide contributes to grain boundary strengthening. The temperature at which the grain boundary is improved by carbide decoration was higher for a cold-worked specimen, which was described by the difference in carbide stability and carbide formation kinetics between no cold-worked and cold-worked specimens. Zr and Hf played a scavenging effect of harmful elements causing an increase in ductility.

  12. Influence of Chromium and Molybdenum on the Corrosion of Nickel Based Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hayes, J R; Gray, J; Szmodis, A W; Orme, C A

    2005-08-02

    The addition of chromium and molybdenum to nickel creates alloys with exceptional corrosion resistance in a diverse range of environments. This study examines the complementary roles of Cr and Mo in Ni alloy passivation. Four nickel alloys with varying amounts of chromium and molybdenum were studied in 1 molar salt solutions over a broad pH range. The passive corrosion and breakdown behavior of the alloys suggests that chromium is the primary element influencing general corrosion resistance. The breakdown potential was nearly independent of molybdenum content, while the repassivation potential is strongly dependant on the molybdenum content. This indicates that chromium plays a strong role in maintaining the passivity of the alloy, while molybdenum acts to stabilize the passive film after a localized breakdown event.

  13. Directionally Solidified NiAl-Based Alloys Studied for Improved Elevated-Temperature Strength and Room-Temperature Fracture Toughness

    Science.gov (United States)

    Whittenberger, J. Daniel; Raj, Sai V.; Locci, Ivan E.; Salem, Jonathan A.

    2000-01-01

    Efforts are underway to replace superalloys used in the hot sections of gas turbine engines with materials possessing better mechanical and physical properties. Alloys based on the intermetallic NiAl have demonstrated potential; however, they generally suffer from low fracture resistance (toughness) at room temperature and from poor strength at elevated temperatures. Directional solidification of NiAl alloyed with both Cr and Mo has yielded materials with useful toughness and elevated-temperature strength values. The intermetallic alloy NiAl has been proposed as an advanced material to extend the maximum operational temperature of gas turbine engines by several hundred degrees centigrade. This intermetallic alloy displays a lower density (approximately 30-percent less) and a higher thermal conductivity (4 to 8 times greater) than conventional superalloys as well as good high-temperature oxidation resistance. Unfortunately, unalloyed NiAl has poor elevated temperature strength (approximately 50 MPa at 1027 C) and low room-temperature fracture toughness (about 5 MPa). Directionally solidified NiAl eutectic alloys are known to possess a combination of high elevated-temperature strength and good room-temperature fracture toughness. Research has demonstrated that a NiAl matrix containing a uniform distribution of very thin Cr plates alloyed with Mo possessed both increased fracture toughness and elevated-temperature creep strength. Although attractive properties were obtained, these alloys were formed at low growth rates (greater than 19 mm/hr), which are considered to be economically unviable. Hence, an investigation was warranted of the strength and toughness behavior of NiAl-(Cr,Mo) directionally solidified at faster growth rates. If the mechanical properties did not deteriorate with increased growth rates, directional solidification could offer an economical means to produce NiAl-based alloys commercially for gas turbine engines. An investigation at the NASA Glenn

  14. Marginal adaptation and micro-porosity of class II restorations of a high copper amalgam and a palladium-free gallium-based alloy.

    Science.gov (United States)

    Shaini, F J; Wahab, F K; Ellakwa, A E; Shortall, A C C; Fleming, G J P; Marquis, P M

    2006-12-01

    The aim of the current investigation was to compare the marginal adaptation and internal porosity of a gallium (Ga)-based alloy (Galloy) with a high copper amalgam (Permite C DP) when used in moderately sized conventional class II cavities. Ten dentists placed two restorations of each material in standardized class II cavities in typodont teeth set in a phantom head. The proximal surfaces of the restored teeth were subsequently examined using an optical microscope and colour photographs were taken. The teeth were then serially sectioned before being re-examined microscopically and re-photographed. Three dentists rated the photographs of the restorations on two occasions, 2 weeks apart, for marginal adaptation and internal porosity using a six and five point scoring criteria, respectively. Inter- and intra-examiner agreements were assessed with weighted kappa statistics. The Ga-based alloy exhibited inferior marginal adaptation and a significantly higher level of porosity and internal defects compared with the dental amalgam. Marginal defects were mainly concentrated at the gingival third of the proximal boxes for both alloys. The poor marginal adaptation and extensive internal porosity detected for the Ga-based alloy was attributed to the difficulty in the alloy condensation related mainly to the 'stickiness' of the alloy to the condensers and to the rapid change in the plasticity of the alloy during condensation. This could possibly be a factor in the post-operative complications reported with the clinical use of this alloy.

  15. Assessing the Effects of Radiation Damage on Ni-base Alloys for the Prometheus Space Reactor System

    Energy Technology Data Exchange (ETDEWEB)

    T Angeliu; J Ward; J Witter

    2006-04-04

    Ni-base alloys were considered for the Prometheus space reactor pressure vessel with operational parameters of {approx}900 K for 15 years and fluences up to 160 x 10{sup 20} n/cm{sup 2} (E > 0.1 MeV). This paper reviews the effects of irradiation on the behavior of Ni-base alloys and shows that radiation-induced swelling and creep are minor considerations compared to significant embrittlement with neutron exposure. While the mechanism responsible for radiation-induced embrittlement is not fully understood, it is likely a combination of helium embrittlement and solute segregation that can be highly dependent on the alloy composition and exposure conditions. Transmutation calculations