WorldWideScience

Sample records for dense ceramic coatings

  1. Dense high temperature ceramic oxide superconductors

    Science.gov (United States)

    Landingham, Richard L.

    1993-01-01

    Dense superconducting ceramic oxide articles of manufacture and methods for producing these articles are described. Generally these articles are produced by first processing these superconducting oxides by ceramic processing techniques to optimize materials properties, followed by reestablishing the superconducting state in a desired portion of the ceramic oxide composite.

  2. Dense ceramic membranes for methane conversion

    NARCIS (Netherlands)

    Bouwmeester, Henny J.M.

    2003-01-01

    Dense ceramic membranes made from mixed oxygen-ionic and electronic conducting perovskite-related oxides allow separation of oxygen from an air supply at elevated temperatures (>700 °C). By combining air separation and catalytic partial oxidation of methane to syngas into a ceramic membrane reactor,

  3. Applications of sol gel ceramic coatings

    Energy Technology Data Exchange (ETDEWEB)

    Barrow, D. [Datec Coating Corp., Kingston, Ont. (Canada)

    1996-12-31

    The sol gel method is a chemical technique in which polycrystalline ceramic films are fabricated from a solution of organometallic precursors. The technique is attractive for many industrial applications because it is a simple (films are processed in air), flexible (can be used to coat complex geometries) and cost effective (does not require expensive equipment) process. In addition, dense, high quality coatings can be achieved at much lower temperatures than is generally required for sintering bulk ceramics. In this paper the conventional sol gel method and the new datec process are reviewed and potential applications of sol gel coatings in automotive, aerospace, petrochemical, nuclear and electronic industries are discussed. (orig.)

  4. SUPPORTED DENSE CERAMIC MEMBRANES FOR OXYGEN SEPARATION

    Energy Technology Data Exchange (ETDEWEB)

    Timothy L. Ward

    2002-07-01

    Mixed-conducting ceramics have the ability to conduct oxygen with perfect selectivity at elevated temperatures, making them extremely attractive as membrane materials for oxygen separation and membrane reactor applications. While the conductivity of these materials can be quite high at elevated temperatures (typically 800-1000 C), much higher oxygen fluxes, or, alternatively, equivalent fluxes at lower temperatures, could be provided by supported thin or thick film membrane layers. Based on that motivation, the objective of this project was to explore the use of ultrafine aerosol-derived powder of a mixed-conducting ceramic material for fabrication of supported thick-film dense membranes. The project focused on the mixed-conducting ceramic composition SrCo{sub 0.5}FeO{sub x} (SCFO) because of the desirable permeability and stability of that material, as reported in the literature. Appropriate conditions to produce the submicron SrCo{sub 0.5}FeO{sub x} powder using aerosol pyrolysis were determined. Porous supports of the same composition were produced by partial sintering of a commercially obtained powder that possessed significantly larger particle size than the aerosol-derived powder. The effects of sintering conditions (temperature, atmosphere) on the porosity and microstructure of the porous discs were studied, and a standard support fabrication procedure was adopted. Subsequently, a variety of paste and slurry formulations were explored utilizing the aerosol-derived SCFO powder. These formulations were applied to the porous SCFO support by a doctor blade or spin coating procedure. Sintering of the supported membrane layer was then conducted, and additional layers were deposited and sintered in some cases. The primary characterization methods were X-ray diffraction and scanning electron microscopy, and room-temperature nitrogen permeation was used to assess defect status of the membranes.We found that non-aqueous paste/slurry formulations incorporating

  5. Corrosion Resistance of Ceramic Coating on Steel Substrate

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Fe/Al2O3 ceramic coating was made by spraying and sol-gel. The corrosion resistance between Fe/Al2O3 ceramic coating and steel 45# was studied. By microscope and X-ray diffraction, the binding and the composition of the interface were also analyzed. The results showed that Fe/Al2O3 ceramic coating had dense structure, less porosity and better binding with the substrate which was effective to prevent erosive liquor immersing into the inside of ceramic coating. Some substances that distributed homogeneously in Fe/Al2O3 ceramic coating,such as α-Al2O3, FeAlO3 and Fe3Al, could improve the corrosion resistance of this material.

  6. Nano-Ceramic Coated Plastics

    Science.gov (United States)

    Cho, Junghyun

    2013-01-01

    Plastic products, due to their durability, safety, and low manufacturing cost, are now rapidly replacing cookware items traditionally made of glass and ceramics. Despite this trend, some still prefer relatively expensive and more fragile ceramic/glassware because plastics can deteriorate over time after exposure to foods, which can generate odors, bad appearance, and/or color change. Nano-ceramic coatings can eliminate these drawbacks while still retaining the advantages of the plastic, since the coating only alters the surface of the plastic. The surface coating adds functionality to the plastics such as self-cleaning and disinfectant capabilities that result from a photocatalytic effect of certain ceramic systems. These ceramic coatings can also provide non-stick surfaces and higher temperature capabilities for the base plastics without resorting to ceramic or glass materials. Titanium dioxide (TiO2) and zinc oxide (ZnO) are the candidates for a nano-ceramic coating to deposit on the plastics or plastic films used in cookware and kitchenware. Both are wide-bandgap semiconductors (3.0 to 3.2 eV for TiO2 and 3.2 to 3.3 eV for ZnO), so they exhibit a photocatalytic property under ultraviolet (UV) light. This will lead to decomposition of organic compounds. Decomposed products can be easily washed off by water, so the use of detergents will be minimal. High-crystalline film with large surface area for the reaction is essential to guarantee good photocatalytic performance of these oxides. Low-temperature processing (nano-ceramic coatings (TiO2, ZnO) on plastic materials (silicone, Teflon, PET, etc.) that can possess both photocatalytic oxide properties and flexible plastic properties. Processing cost is low and it does not require any expensive equipment investment. Processing can be scalable to current manufacturing infrastructure.

  7. The application of plasma-sprayed ceramic coatings on lift roller in float glass

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Oxide ceramic was sprayed via high-energy plasma spray using MCrAlY manufactured with special technique as bond coating and oxide ceramic as top coating in this article. Investigation showed that the dense and highly adhesive coating could be obtained with optimized technique. After grinding and polishing, coating roughness was lower than 0. 2μm, which could meet the requirements of lift roller. After one year serv ice, molten Tin could not adhere to the ceramic coating,well it greatly alleviated its corrosion to the roller , kept the surface of oxide ceramic coating smooth and the improve the quality of glass due to the strengthened lift roll.

  8. SUPPORTED DENSE CERAMIC MEMBRANES FOR OXYGEN SEPARATION

    Energy Technology Data Exchange (ETDEWEB)

    Timothy L. Ward

    2000-06-30

    Mixed-conducting membranes have the ability to conduct oxygen with perfect selectivity at elevated temperatures, which makes them an extremely attractive alternative for oxygen separation and membrane reactor applications. The ability to reliably fabricate these membranes in thin or thick films would enable solid-state divisional limitations to be minimized, thus providing higher oxygen flux. Based on that motivation, the overall objective for this project is to develop and demonstrate a strategy for the fabrication of supported Wick film ceramic mixed conducting membranes, and improve the understanding of the fundamental issues associated with reliable fabrication of these membranes. The project has focused on the mixed-conducting ceramic composition SrCo{sub 0.5}FeO{sub x} because of its superior permeability and stability in reducing atmospheres. The fabrication strategy employed involves the deposition of SrCo{sub 0.5}FeO{sub x} thick films onto porous supports of the same composition. In the second year of this project, we completed characterization of the sintering and phase behavior of the porous SrCo{sub 0.5}FeO{sub x} supports, leading to a standard support fabrication methodology. Using a doctor blade method, pastes made from aerosol-derived SrCo{sub 0.5}FeO{sub x} powder dispersed with polyethylene glycol were applied to the supports, and the sintering behavior of the thick film membranes was examined in air and nitrogen atmospheres. It has been demonstrated that the desired crystalline phase content can be produced in the membranes, and that the material in the membrane layer can be highly densified without densifying the underlying support. However, considerable cracking and opening of the film occurred when films densified to a high extent. The addition of MgO into the SrCo{sub 0.5}FeO{sub x} supports was shown to inhibit support sintering so that temperatures up to 1300 C, where significant liquid formation occurs, could be used for film sintering

  9. Easy Fabrication of Dense Ceramic Membrane for Oxygen Separation

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A combined EDTA-citrate complexing method was developed for the easy preparation of mixed oxygen-ionic and electronic conducting dense ceramic membrane for oxygen separation.The new method takes the advantage of lower calcination temperature for phase formation, lower membrane sintering temperature and higher relative density over the standard ceramic method.

  10. Tribological Behaviour of the Ceramic Coating Formed on Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    CHEN Fei; ZHOU Hai; CHEN Qiang; GE Yuanjing; LV Fanxiu

    2007-01-01

    Micro-arc oxidation is a recently developed surface treatment technology under anodic oxidation. Through micro-arc oxidation, a ceramic coating is directly formed on the surface of magnesium alloy, by which its surface property is significantly improved. In this paper, a dense ceramic oxide coating was prepared on an AZ31 magnesium alloy by micro-arc oxidation in a NaOH-Na2SiO3-NaB4O7-(NaPO3)6 electrolytic solution. Micro-structure, surface morphology and phase composition were analysed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The tribological behavior of the micro-arc oxidation ceramic coating under dry sliding against GCrl5 steel was evaluated on a ball-on-disc test rig. The results showed that the AZ31 alloy was characterized by adhesion wear and scuffing under dry sliding against the steel, while the surface micro-arc oxidation ceramic coating experienced much abated adhesion wear and scuffing under the same testing conditions. The micro-arc oxidation ceramic coating showed good friction-reducing and fair antiwear ability in dry sliding against the steel.

  11. Development on Laser Cladding Ceramic Coating

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The latest progress and research status of laser cladding ceramic coating was summarized. Technique characteristics and influence factors of laser cladding technique were introduced. Laser cladding technique includes the mixing method and laser irradiation. The mixing method can be classified as pre-coating method and synchronization method. The technique parameters include size of facula, scanning speed, cladding sector and times, adding quantity of powder, thickness of coating and quantity of joint coating. The results show that proper technique parameters can be controlled in order to acquire high quality laser cladding coating. Strengthened effect mechanism of rare earth additive is concluded, and the main effects of rare earth additive are micro-alloying, purifying boundary, fining crystal grains, improving crystal boundary, restraining columnar crystal growing. The development of laser cladding ceramic coating research was discussed.

  12. Cr-Free Metallic-Ceramic Coatings

    Science.gov (United States)

    2014-11-01

    Cr -FREE METALLIC-CERAMIC COATINGS ASETS Defense 2014 Fort Myer, VA, November 18-20, 2014 Bruce McMordie Coatings for Industry 319...SNECMA Alseal® 5K Aluminum-Silicate Al-Silicate Coating System Now Available That Can Eliminate Hazards of Carcinogenic Cr +6 in Al...OMB control number. 1. REPORT DATE NOV 2014 2. REPORT TYPE 3. DATES COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE Cr -Free Metallic

  13. Method for non-destructive evaluation of ceramic coatings

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, Kristen A.; Rosen, Elias P.; Jordan, Eric H.; Shahbazmohamadi, Sina; Vakhtin, Andrei B.

    2016-11-08

    A method for evaluating the condition of a ceramic coating deposited on a substrate comprising illuminating the ceramic coating with light, measuring the intensity of light returned from the ceramic coating as function of depth in the coating and transverse position on the coating, and analyzing the measured light intensities to obtain one or more of intensity of the light returned from the exposed coating surface relative to the intensity of light returned from the coating/substrate interface, intensity of the light returned from the coating/substrate interface relative to the intensity of light returned from the bulk of the ceramic coating, determination of roughness at the exposed surface of the ceramic coating, and determination of roughness of the interface between the ceramic coating and underlying bond coat or substrate.

  14. Method for non-destructive evaluation of ceramic coatings

    Science.gov (United States)

    Peterson, Kristen A.; Rosen, Elias P.; Jordan, Eric H.; Shahbazmohamadi, Sina; Vakhtin, Andrei B.

    2016-11-08

    A method for evaluating the condition of a ceramic coating deposited on a substrate comprising illuminating the ceramic coating with light, measuring the intensity of light returned from the ceramic coating as function of depth in the coating and transverse position on the coating, and analyzing the measured light intensities to obtain one or more of intensity of the light returned from the exposed coating surface relative to the intensity of light returned from the coating/substrate interface, intensity of the light returned from the coating/substrate interface relative to the intensity of light returned from the bulk of the ceramic coating, determination of roughness at the exposed surface of the ceramic coating, and determination of roughness of the interface between the ceramic coating and underlying bond coat or substrate.

  15. High-temperature corrosion resistance of ceramics and ceramic coatings

    Energy Technology Data Exchange (ETDEWEB)

    Tortorelli, P.F.

    1996-06-01

    Ceramics and ceramic composites offer the potential to operate fossil energy systems at the higher temperatures necessary for improved energy efficiency and better environmental control. However, because many fossil fuel-derived processes contain sulfur, chlorine, and carbon, as well as oxygen, degradation from high-temperature corrosion and environmental effects arising from reactions of solids with gases and condensable products is a common life-determining factor in operating systems. Ceramic-based products are not immune to such degradation; adequate corrosion resistance must be assured to exploit the technical and economic potential of such materials. This is normally accomplished by using stable, sound oxides that exist in their bulk form, that naturally grow as surface layers upon exposure to an oxidizing environment, or that are deposited as a coating on a susceptible material. It is therefore important to examine the critical issues with respect to more environmental stability of ceramics that have the potential to be corrosion resistant in particular fossil environments. Key aspects include not only chemical compatibility, but the influence of the environment on the mechanical behavior of the ceramic materials. In addition, for coatings, the mechanical reliability of the ceramic is a key issue in that an otherwise corrosion-resistant surface layer must remain sound and adherent in order to provide protection to the underlying substrate. The purpose of this work is to support the development of advanced ceramics and ceramic composites for applications in fossil environments by examining critical issues related to high-temperature corrosion resistance. More specifically, the overall objective of this task is to examine the chemical compatibility and reliability of potentially corrosion-resistant ceramics being developed as protective overcoats and/or structural materials as parts of other work elements funded by the AR&TD Program.

  16. Preparation and properties of nano-composite ceramic coating by thermo chemical reaction method

    Institute of Scientific and Technical Information of China (English)

    MA Zhuang; SUN Fang-hong; LI Zhi-chao

    2007-01-01

    Nano-composite ceramic coating was fabricated on Q235 steel through thermo chemical reaction method. Structure of the coating was analyzed and the properties were tested. The results show that a few of new ceramic phases, such as MgAl2O4, ZnAl2O4,Al2SiO5, Ni3Fe and Fe3Al, are formed on the coating during the process of solidifying at 600 ℃. The ceramic coating is dense and the high bonding strength is obtained. The average bonding strength between the coating and matrix could be 14.22 MPa. The acid resistance of the coating increase by 8.8 times, the alkali resistance by 4.1 times, the salt resistance by 10.3 times, and the wear resistance by 2.39 times.

  17. Effect of mechanical cycling on the flexural strength of densely sintered ceramics

    NARCIS (Netherlands)

    Itinoche, Koiti Marco; Ozcan, Mudu; Bottino, Marco Antonio; Oyafuso, Denise

    2006-01-01

    Objectives. The aim of this study was to evaluate the effect of mechanical cycling on the biaxial flexural strength of two densely sintered ceramic materials. Methods. Disc shaped zirconia (In-Ceram Zirconia) and high alumina (Procera AllCeram) ceramic specimens (diameter: 15 min and thickness: 1.2

  18. Nanoscale Reinforced, Polymer Derived Ceramic Matrix Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Rajendra Bordia

    2009-07-31

    The goal of this project was to explore and develop a novel class of nanoscale reinforced ceramic coatings for high temperature (600-1000 C) corrosion protection of metallic components in a coal-fired environment. It was focused on developing coatings that are easy to process and low cost. The approach was to use high-yield preceramic polymers loaded with nano-size fillers. The complex interplay of the particles in the polymer, their role in controlling shrinkage and phase evolution during thermal treatment, resulting densification and microstructural evolution, mechanical properties and effectiveness as corrosion protection coatings were investigated. Fe-and Ni-based alloys currently used in coal-fired environments do not possess the requisite corrosion and oxidation resistance for next generation of advanced power systems. One example of this is the power plants that use ultra supercritical steam as the working fluid. The increase in thermal efficiency of the plant and decrease in pollutant emissions are only possible by changing the properties of steam from supercritical to ultra supercritical. However, the conditions, 650 C and 34.5 MPa, are too severe and result in higher rate of corrosion due to higher metal temperatures. Coating the metallic components with ceramics that are resistant to corrosion, oxidation and erosion, is an economical and immediate solution to this problem. Good high temperature corrosion protection ceramic coatings for metallic structures must have a set of properties that are difficult to achieve using established processing techniques. The required properties include ease of coating complex shapes, low processing temperatures, thermal expansion match with metallic structures and good mechanical and chemical properties. Nanoscale reinforced composite coatings in which the matrix is derived from preceramic polymers have the potential to meet these requirements. The research was focused on developing suitable material systems and

  19. Bioactive glass-ceramics coatings on alumina

    Energy Technology Data Exchange (ETDEWEB)

    Vitale Brovarone, C.; Verne, E.; Lupo, F. [Politecnico di Torino (Italy). Materials Science and Chemical Eng. Dept.; Moisescu, C. [Jena Univ. (Germany). Otto-Schott-Inst. fuer Glaschemie; Zanardi, L.; Bosetti, M.; Cannas, M. [Eastern Piemont Univ., Novara (Italy). Medical Science Dept.

    2001-07-01

    In this work, aiming to combine the mechanical performances of alumina with the surface properties of a bioactive material, we coated full density alumina substrates by a bioactive glass-ceramic GC. This latter was specially tailored, in term of costituents and specific quantity to have a thermal expansion coefficient close to that of alumina (8.5-9{sup *}10{sup -6}/ C) which is lower than most of the bioactive glasses and glass-ceramics already in use. In this way, we sought to avoid, as much as possible, the crack formation and propagation due to residual stresses generated by the thermal expansion coefficients mismatch. Furthermore, the high reactivity of alumina toward the glass-ceramic was carefully controlled to avoid deep compositional modification of the GC that will negatively affect its bioactivity. At this purpose, an intermediate layer of an appropriate glass G was coated prior to coat the bioactive glass-ceramic. On the materials obtained, preliminary biological tests have been done to evaluate glass-ceramic biocompatibility respect to alumina. (orig.)

  20. Application of magnetron sputtering for producing bioactive ceramic coatings on implant materials

    Indian Academy of Sciences (India)

    J Z Shi; C Z Chen; H J Yu; S J Zhang

    2008-11-01

    Radio frequency (RF) magnetron sputtering is a versatile deposition technique that can produce thin, uniform, dense calcium phosphate coatings. In this paper, principle and character of magnetron sputtering is introduced, and development of the hydroxyapatite and its composite coatings application is reviewed. In addition, influence of heat treatment on magnetron sputtered coatings is discussed. The heat treated coatings have been shown to exhibit bioactive behaviour both in vivo and in vitro. At last, the future application of the bioactive ceramic coating deposited by magnetron sputtering is mentioned.

  1. Wear and microstructure in fine ceramic coatings

    Energy Technology Data Exchange (ETDEWEB)

    Vijande-Diaz, R.; Belzunce, J.; Fernandez, E. (ETS de Ingenieros Industriales, Area de Ingeneria Mecanica, Gijon (Spain)); Rincon, A.; Perez, M.C. (Inst. de Fisica-Quimica ' Roco Solano' , CSIC, Madrid (Spain))

    1991-08-15

    This paper presents a study of the wear resistance of two ceramic, plasma sprayed coatings of Al{sub 2}O{sub 3} and Cr{sub 2}O{sub 3}. Tests were carried out using an LWF-1 standard machine, with lineal contact, under dry friction, abrasion and lubricant conditions. The purpose of the tests were to study how load and speed affect material wear. Results show the lower wear rate of the ceramic coating compared with the steel one, as well as how remarkably load affects wear. On the other hand, however, considering the speed ranges used, wear resistance does not depend significantly on speed. The paper proves that the wear process follows Czichos' law. At the same time, reformulation of Archard's equation allows us to quantify wear using easily measurable factors such as pressure, speed, hardness, and those factors typically featuring this type of coatings, e.g. porosity. Also, a micrographic study of the coatings carried out by means of a scanning electron microscope has evidenced three stages in the wear mechanism: (a) plastic deformation of particles; (b) crack nucleation and propagation; and (c) loosening of ceramic particles. (orig.).

  2. Fabrication, characterization, and fluorine-plasma exposure behavior of dense yttrium oxyfluoride ceramics

    Science.gov (United States)

    Tsunoura, Toru; Yoshida, Katsumi; Yano, Toyohiko; Kishi, Yukio

    2017-06-01

    Yttrium oxyfluoride (YOF) ceramics are expected to be one of the attractive plasma-resistant materials for semiconductor production equipment. In this study, dense YOF ceramics were fabricated by hot pressing using YOF powder, and their physical, mechanical, and thermal properties were characterized. Moreover, behavior against fluorine-plasma exposure was investigated. The results suggest that the YOF ceramics showed excellent mechanical and thermal properties, and superior resistance for fluorine-plasma exposure to Y2O3 ceramics.

  3. Lead-free piezoelectric ceramic coatings fabricated by thermal spray process.

    Science.gov (United States)

    Yao, Kui; Chen, Shuting; Guo, Kun; Tan, Chee Kiang Ivan; Mirshekarloo, Meysam Sharifzadeh; Tay, Francis Eng Hock

    2017-09-04

    The paper starts from a review on the progress in fabrication of piezoelectric ceramic coatings by thermal spray method. For our experimental work, two types of lead-free piezoelectric ceramic coatings, including potassium sodium niobate (KNN)-based and bismuth sodium titanate (BNT)-based, are fabricated by thermal spray process, and their structure, morphology and piezoelectric properties are characterized. Our obtained lead-free ceramic coatings exhibit single phase of perovskite structure, relatively dense morphology, and competitive piezoelectric coefficients. The mechanism of forming the piezoelectric perovskite crystalline phase by thermal spray involving melting-recrystallization process is analyzed in comparison to that of ceramic synthesis through solid state reaction. Suppression of volatile loss and decomposition at high temperature due to the extremely high melting and cooling rate in the thermal spray process, and the impact on the resulting structure are discussed. Significant advantages of the thermal spray method over alternative processing methods for forming piezoelectric ceramic coatings are summarized. The combination of environmentally friendly lead-free compositions and the scalable thermal spray processing method will promote more applications of piezoelectric ceramic coatings for producing distributive sensors and transducers, and forming advanced smart structures and systems.

  4. Dense protective coatings, methods for their preparation and coated articles

    Energy Technology Data Exchange (ETDEWEB)

    Tulyani, Sonia; Bhatia, Tania; Smeggil, John G.

    2015-12-29

    A method for depositing a protective coating on a complex shaped substrate includes the steps of: (1) dipping a complex shaped substrate into a slurry to form a base coat thereon, the slurry comprising an aqueous solution, at least one refractory metal oxide, and at least one transient fluid additive present in an amount of about 0.1 percent to 10 percent by weight of the slurry; (2) curing the dipped substrate; (3) dipping the substrate into a precursor solution to form a top barrier coat thereon; and (4) heat treating the dipped, cured substrate to form a protective coating.

  5. Theoretical analysis of thermal shock resistance of ceramic foam coatings

    Science.gov (United States)

    Zhang, Y. X.; Wang, B. L.

    2017-01-01

    Ceramic foams have a high resistance to corrosion and wear. They also have a good thermal insulation performance because of their high melting point and low thermal conductivity. The thermal shock resistance of a ceramic foam coating with an edge crack under a sudden temperature variation is investigated. The dynamic thermal stress fields in the ceramic foam coating are obtained. Using the superposition principle, the crack problem of the ceramic foam coating is reduced to the solution of a set of singular integral equations. Propagation of the edge crack is analyzed. Effects of the relative density and thermal properties of the ceramic foam and of crack length on the thermal shock resistance are identified. The results obtained can be useful in designing thermal protective ceramic materials for thermal barrier coatings.

  6. High temperature ceramic articles having corrosion resistant coating

    Science.gov (United States)

    Stinton, David P.; Lee, Woo Y.

    1997-01-01

    A ceramic article which includes a porous body of SiC fibers, Si.sub.3 N.sub.4 fibers, SiC coated fibers or Si.sub.3 N.sub.4 coated fibers, having at least one surface, the article having a coating of AlN adherently disposed throughout at least a portion of the porous body.

  7. Mo-Si-B-Based Coatings for Ceramic Base Substrates

    Science.gov (United States)

    Perepezko, John Harry (Inventor); Sakidja, Ridwan (Inventor); Ritt, Patrick (Inventor)

    2015-01-01

    Alumina-containing coatings based on molybdenum (Mo), silicon (Si), and boron (B) ("MoSiB coatings") that form protective, oxidation-resistant scales on ceramic substrate at high temperatures are provided. The protective scales comprise an aluminoborosilicate glass, and may additionally contain molybdenum. Two-stage deposition methods for forming the coatings are also provided.

  8. Improving Erosion Resistance of Plasma-Sprayed Ceramic Coatings by Elevating the Deposition Temperature Based on the Critical Bonding Temperature

    Science.gov (United States)

    Yao, Shu-Wei; Yang, Guan-Jun; Li, Cheng-Xin; Li, Chang-Jiu

    2017-09-01

    Interlamellar bonding within plasma-sprayed coatings is one of the most important factors dominating the properties and performance of coatings. The interface bonding between lamellae significantly influences the erosion behavior of plasma-sprayed ceramic coatings. In this study, TiO2 and Al2O3 coatings with different microstructures were deposited at different deposition temperatures based on the critical bonding temperature concept. The erosion behavior of ceramic coatings was investigated. It was revealed that the coatings prepared at room temperature exhibit a typical lamellar structure with numerous unbonded interfaces, whereas the coatings deposited at the temperature above the critical bonding temperature present a dense structure with well-bonded interfaces. The erosion rate decreases sharply with the improvement of interlamellar bonding when the deposition temperature increases to the critical bonding temperature. In addition, the erosion mechanisms of ceramic coatings were examined. The unbonded interfaces in the conventional coatings act as pre-cracks accelerating the erosion of coatings. Thus, controlling interlamellar bonding formation based on the critical bonding temperature is an effective approach to improve the erosion resistance of plasma-sprayed ceramic coatings.

  9. Hardness and electrochemical behavior of ceramic coatings on Inconel

    Directory of Open Access Journals (Sweden)

    C. SUJAYA

    2012-03-01

    Full Text Available Thin films of ceramic materials like alumina and silicon carbide are deposited on Inconel substrate by pulsed laser deposition technique using Q-switched Nd: YAG laser. Deposited films are characterized using UV-visible spectrophotometry and X-ray diffraction. Composite microhardness of ceramic coated Inconel system is measured using Knoop indenter and its film hardness is separated using a mathematical model based on area-law of mixture. It is then compared with values obtained using nanoindentation method. Film hardness of the ceramic coating is found to be high compared to the substrates. Corrosion behavior of substrates after ceramic coating is studied in 3.5% NaCl solution by potentiodynamic polarization and electrochemical impedance spectroscopy measurements. The Nyquist and the Bode plots obtained from the EIS data are fitted by appropriate equivalent circuits. The pore resistance, the charge transfer resistance, the coating capacitance and the double layer capacitance of the coatings are obtained from the equivalent circuit. Experimental results show an increase in corrosion resistance of Inconel after ceramic coating. Alumina coated Inconel showed higher corrosion resistance than silicon carbide coated Inconel. After the corrosion testing, the surface topography of the uncoated and the coated systems are examined by scanning electron microscopy.

  10. Guanidine Soaps As Vehicles For Coating Ceramic Fibers

    Science.gov (United States)

    Philipp, Warren H.; Veitch, Lisa C.; Jaskowiak, Martha H.

    1994-01-01

    Soaps made from strong organic base guanidine and organic fatty acids serve as vehicles and binders for coating ceramic fibers, various smooth substrates, and other problematic surfaces with thin precious-metal or metal-oxide films. Films needed to serve as barriers to diffusion in fiber/matrix ceramic composite materials. Guanidine soaps entirely organic and burn off, leaving no residues.

  11. Plasma spray deposition of graded metal-ceramic coatings

    Energy Technology Data Exchange (ETDEWEB)

    Musil, J. (Inst. of Tech. and Reliability of Structures, Czechoslovak Academy of Sciences, Plzen (Czechoslovakia)); Fiala, J. (Central Research Inst., Plzen (Czechoslovakia))

    1992-05-20

    Plasma spraying of graded coatings is described and the metal-ceramic interface of the graded intermediate zone is analysed in terms of a simple physical model. Special attention is devoted to the dominant deposition parameters, powder characteristics and the injector configuration for powder feeding, which play a fundamental role in graded coating deposition with controlled formation of a metal-ceramic intermediate zone. On the basis of a knowledge of these parameters, a new and original formula for the coefficient of homogeneity for simultaneous deposition of metal and ceramic particles at the same spot on the substrate is derived. Furthermore, very interesting topotactical relations are described for the metal-ceramic interface of the graded zone. Various techniques of structural analysis (X-ray diffraction, scanning electron microscopy, optical microscopy) and simple thermodynamic calculations allow a new interpretation to be given of the bonding between the metal and ceramic components. The cohesion of graded metal-ceramic coatings is predicted to be higher than that of ceramic coatings with a metallic bond layer. The results are illustrated by a NiCr-ZrO{sub 2}(MgO) graded coating. (orig.).

  12. Study on the neotype zirconia's implant coated nanometer hydroxyapatite ceramics

    Science.gov (United States)

    Zhu, J. W.; Yang, D. W.

    2007-07-01

    In recent years, biologic ceramics is a popular material of implants and bioactive surface modification of dental implant became a research emphasis, which aims to improve bioactivity of implants materials and acquire firmer implants-bone interface. The zirconia ceramic has excellent mechanical properties and nanometer HA ceramics is a bioceramic well known for its bioactivity, therefore, nanometer HA ceramics coating on zirconia, allows combining the excellent mechanical properties of zirconia substrates with its bioactivity. This paper shows a new method for implant shape design and bioactive modification of dental implants surface. Zirconia's implant substrate was prepared by sintered method, central and lateral tunnels were drilled in the zirconia hollow porous cylindrical implants by laser processing. The HA powders and needle-like HA crystals were made by a wet precipitation and calcining method. Its surface was coated with nanometer HA ceramics which was used brush HA slurry and vacuum sintering. Mechanical testing results revealed that the attachment strength of nanometer HA ceramics coated zirconia samples is high. SEM and interface observation after inserted experiment indicated that calcium and phosphor content increased and symmetrically around coated implant-bone tissue interface. A significantly higher affinity index was demonstrated in vivo by histomorphometric evaluation in coated versus uncoated implants. SEM analysis demonstrated better bone adhesion to the material in coated implant at any situation. In addition, the hollow porous cylindrical implant coated with nanometer HA ceramics increase the interaction of bone and implant, the new bone induced into the surface of hollow porous cylindrical implant and through the most tunnels filled into central hole. The branch-like structure makes the implant and bone a body, which increased the contact area and decreased elastic ratio. Therefore, the macroscopical and microcosmic nested structure of

  13. Interpenetrating phase ceramic/polymer composite coatings: Fabrication and characterization

    Science.gov (United States)

    Craig, Bradley Dene

    The goals of this thesis research were to fabricate interpenetrating phase composite (IPC) ceramic/polymer coatings and to investigate the effect of the interconnected microstructure on the physical and wear properties of the coatings. IPC coatings with an interpenetrating phase microstructure were successfully fabricated by first forming a porous ceramic with an interconnected microstructure using a chemical bonding route (mainly reacting alpha-alumina (0.3 mum) with orthophosphoric acid to form a phosphate bond). Porosity within these ceramic coatings was easily controlled between 20 and 50 vol. % by phosphoric acid addition, and was measured by a new porosity measurement technique (thermogravimetric volatilization of liquids, or TVL) which was developed. The resulting ceramic preforms were infiltrated with a UV and thermally curable cycloaliphatic epoxide resin and cured. This fabrication route resulted in composite coatings with thicknesses ranging from ˜1mum to 100 mum with complete filling of open pore space. The physical properties of the composite coatings, including microhardness, flexural modulus and wear resistance, were evaluated as a function of processing variables, including orthophosphoric acid content and ceramic phase firing temperature, which affected the microstructure and interparticulate bonding between particles in the coatings. For example, microhardness increased from ˜30 on the Vicker's scale to well over 200 as interparticulate bonding was increased in the ceramic phase. Additionally, Taber wear resistance in the best TPC coatings was found to approach that of fully-densified alumina under certain conditions. Several factors were found to influence the wear mechanism in the IPC coating materials. Forming strong connections between ceramic particles led to up to an order of magnitude increase in the wear resistance. Additionally, coating microhardness and ceramic/polymer interfacial strength were studied and found to be important in

  14. Ceramic thermal barrier coatings for gas turbine engines

    Science.gov (United States)

    Bratton, R. J.; Lau, S. K.; Andersson, C. A.; Lee, S. Y.

    1982-01-01

    The results of studies concerning the high temperature corrosion resistance of ZrO2-Y2O3, ZrO2-MgO, and Ca2SiO4 plasma-sprayed coatings, which may be used as gas turbine engine thermal barriers, are reported. The coatings were evaluated in atmospheric burner rig and pressurized passage tests, using GT No. 2 fuel in pure form and with sodium, sulfur and vanadium corrosive impurities doping. It is found that, while the coatings performed well in both pressurized passage and burner rig tests with pure fuel chemical reactions between the ceramic coatings and combustion gases/condensates resulted in coating degradation with impure fuels. Chemical reactions between the ceramic coatings and vanadium compounds played a critical role in coating degradation.

  15. Ceramic coated Y1 magnesium alloy surfaces by microarc oxidation process for marine applications

    Indian Academy of Sciences (India)

    V V Narulkar; S Prakash; K Chandra

    2007-08-01

    The magnesium alloys occupy an important place in marine applications, but their poor corrosion resistance, wear resistance, hardness and so on, have limited their application. To meet these defects, some techniques are developed. Microarc oxidation is a one such recently developed surface treatment technology under anodic oxidation in which ceramic coating is directly formed on the surface of magnesium alloy, by which its surface property is greatly improved. In this paper, a dense ceramic oxide coating, ∼ 20 m thick, was prepared on an Y1 magnesium alloy through microarc oxidation in a Na3SiO3–Na2WO4–KOH–Na2EDTA electrolytic solution. The property of corrosion resistance of ceramic coating was studied by CS300P electrochemistry–corrosion workstation, and the main impact factor of the corrosion resistance was also analysed. Microstructure and phase composition were analysed by SEM and XRD. The microhardness of the coating was also measured. The basic mechanism of microarc coating formation is explained in brief. The results show that the corrosion resistance property of microarc oxidation coating on the Y1 magnesium surface is superior to the original samples in the 3.5 wt% NaCl solutions. The microarc oxidation coating is relatively dense and uniform, mainly composed of MgO, MgAl2O4 and MgSiO3. The microhardness of the Y1 magnesium alloy surface attained 410 HV, which was much larger than that of the original Y1 magnesium alloy without microarc oxidation.

  16. Enhancing thermal barrier coatings performance through reinforcement of ceramic topcoat

    Science.gov (United States)

    Bogdanovich, V. I.; Giorbelidze, M. G.

    2016-11-01

    This paper studies structure of thermal barrier coatings applied to hot gas path components in gas turbine engines and produced in a number of ways, and its impact on performance. Methods of structural reinforcement for ceramic topcoat in thermal barrier coatings are considered.

  17. Finite Element Analysis of Ceramic Coatings under Spherical Indentation with Metallic Interlayer: Part Ⅰ Uncracked Coatings

    Institute of Scientific and Technical Information of China (English)

    Minh-Quy LE; Seock-Sam KIM

    2006-01-01

    Spherical indentation of ceramic coatings with metallic interlayer was performed by means of axisymmetric finite element analysis (FEA). Two typical ceramic coatings with relatively high and low elastic modulus deposited on aluminum alloy and carbon steel were considered. Various combinations of indenter radius-coating thickness ratios and interlayer thickness-coating thickness ratios were used in the modeling. The effects of the interlayer, the coating and the substrate on the indentation behavior, such as the radial stress distribution along the coating surface as well as the coating interface, and the plastic deformation zone evolution in the substrate were investigated in connection with the above mentioned ratios. The coating cracking dominant modes were also discussed within the context of the peak tensile stresses on the coating surface and on the coating interface.

  18. Superhydrophobic Ceramic Coatings by Solution Precursor Plasma Spray

    Science.gov (United States)

    Cai, Yuxuan

    Superhydrophobic surfaces exhibit superior water repellent properties, and they have remarkable potential to improve current energy infrastructure. Substantial research has been performed on the production of superhydrophobic coatings. However, superhydrophobic coatings have not yet been adopted in many industries where potential applications exist due to the limited durability of the coating materials and the complex and costly fabrication processes. Here presented a novel coating technique to manufacture ceramic superhydrophobic coatings rapidly and economically. A rare earth oxide (REO) was selected as the coating material due to its hydrophobic nature and strong mechanical properties, and deposited on stainless steel substrates by solution precursor plasma spray (SPPS). The as-sprayed coating demonstrated a hierarchically structured coating topography, which closely resembles superhydrophobic surfaces in nature. Compared to smooth REO surfaces, the SPPS superhydrophobic coating improved the water contact angle by as much as 65° after vacuum treatment at 1 Pa for 48 hours.

  19. Superhydrophobic Ceramic Coatings by Solution Precursor Plasma Spray

    Science.gov (United States)

    Cai, Yuxuan; Coyle, Thomas W.; Azimi, Gisele; Mostaghimi, Javad

    2016-04-01

    This work presents a novel coating technique to manufacture ceramic superhydrophobic coatings rapidly and economically. A rare earth oxide (REO) was selected as the coating material due to its hydrophobic nature, chemical inertness, high temperature stability, and good mechanical properties, and deposited on stainless steel substrates by solution precursor plasma spray (SPPS). The effects of various spraying conditions including standoff distance, torch power, number of torch passes, types of solvent and plasma velocity were investigated. The as-sprayed coating demonstrated a hierarchically structured surface topography, which closely resembles superhydrophobic surfaces found in nature. The water contact angle on the SPPS superhydrophobic coating was up to 65% higher than on smooth REO surfaces.

  20. Facility for continuous CVD coating of ceramic fibers

    Science.gov (United States)

    Moore, Arthur W.

    1992-01-01

    An inductively heated CVD furnace of pilot-plant scale, whose hot zone is 150 mm in diameter x 300 mm in length, has been adapted for continuous coating of ceramic yarns. Coatings at very low pressures are possible in this facility due to the fact that the entire apparatus, including yarn feeding and collecting equipment, is under vacuum. SiC yarn has been coated with 0.1-0.2 microns of BN at yarn speeds of 60 cm/min; a 500-m spool; was coated in about 14 hrs. Coating capacity was tripled by adding pulleys to allow three yarn passes through the furnace.

  1. Nanostructured glass–ceramic coatings for orthopaedic applications

    Science.gov (United States)

    Wang, Guocheng; Lu, Zufu; Liu, Xuanyong; Zhou, Xiaming; Ding, Chuanxian; Zreiqat, Hala

    2011-01-01

    Glass–ceramics have attracted much attention in the biomedical field, as they provide great possibilities to manipulate their properties by post-treatments, including strength, degradation rate and coefficient of thermal expansion. In this work, hardystonite (HT; Ca2ZnSi2O7) and sphene (SP; CaTiSiO5) glass–ceramic coatings with nanostructures were prepared by a plasma spray technique using conventional powders. The bonding strength and Vickers hardness for HT and SP coatings are higher than the reported values for plasma-sprayed hydroxyapatite coatings. Both types of coatings release bioactive calcium (Ca) and silicon (Si) ions into the surrounding environment. Mineralization test in cell-free culture medium showed that many mushroom-like Ca and phosphorus compounds formed on the HT coatings after 5 h, suggesting its high acellular mineralization ability. Primary human osteoblasts attach, spread and proliferate well on both types of coatings. Higher proliferation rate was observed on the HT coatings compared with the SP coatings and uncoated Ti-6Al-4V alloy, probably due to the zinc ions released from the HT coatings. Higher expression levels of Runx2, osteopontin and type I collagen were observed on both types of coatings compared with Ti-6Al-4V alloy, possibly due to the Ca and Si released from the coatings. Results of this study point to the potential use of HT and SP coatings for orthopaedic applications. PMID:21292725

  2. Surface-enhanced Raman spectroscopy using silver-coated porous glass-ceramic substrates.

    Science.gov (United States)

    Pan, Z; Zavalin, A; Ueda, A; Guo, M; Groza, M; Burger, A; Mu, R; Morgan, S H

    2005-06-01

    Surface-enhanced Raman scattering (SERS) has been studied using a silver-coated porous glass-ceramic material as a new type of substrate. The porous glass-ceramic is in the CaO-TiO2-P2O5 system prepared by controlled crystallization and subsequent chemical leaching of the dense glass-ceramic, leaving a solid skeleton with pores ranging in size from 50 nm to submicrometer. Silver was coated on the surface of the porous glass-ceramic by radio frequency (RF) sputtering or e-beam evaporation in vacuum. SERS spectra of excellent quality were obtained from several dyes and carboxylic acid molecules, including rhodamine 6G, crystal violet, isonicotinic acid, and benzoic acid, using this new substrate. This new substrate showed a good compatibility with these molecules. The porous glass ceramic with a nanometer-structured surface accommodated both test molecules and silver film. The absorbed molecules were therefore better interfaced with silver for surface-enhanced Raman scattering.

  3. Plasma-sprayed ceramic coatings for molten metal environments.

    Energy Technology Data Exchange (ETDEWEB)

    Hollis, K. J. (Kendall J.); Peters, M. I. (Maria I.); Bartram, B. D. (Brian D.)

    2002-01-01

    Coating porosity is an important parameter to optimize for plasma-sprayed ceramics which are intended for service in molten metal environments. Too much porosity and the coatings may be infiltrated by the molten metal causing corrosive attack of the substrate or destruction of the coating upon solidification of the metal. Too little porosity and the coating may fail due to its inability to absorb thermal strains. This study describes the testing and analysis of tungsten rods coated with aluminum oxide, yttria-stabilized zirconia, yttrium oxide, and erbium oxide deposited by atmospheric plasma spraying. The samples were immersed in molten aluminum and analyzed after immersion. One of the ceramic materials used, yttrium oxide, was heat treated at 1000 C and 2000 C and analyzed by X-ray diffractography and mercury intrusion porosimetry. Slight changes in crysl nl structure and significant changes in porosity were observed after heat treatments.

  4. Experimental study of ceramic coated tip seals for turbojet engines

    Science.gov (United States)

    Biesiadny, T. J.; Klann, G. A.; Lassow, E. S.; Mchenry, M.; Mcdonald, G.; Hendricks, R. C.

    1985-01-01

    Ceramic gas-path seals were fabricated and successfully operated over 1000 cycles from flight idle to maximum power in a small turboshaft engine. The seals were fabricated by plasma spraying zirconia over a NiCoCrAlX bond boat on the Haynes 25 substrate. Coolant-side substrate temperatures and related engine parameters were recorded. Post-test inspection revealed mudflat surface cracking with penetration to the ceramic bond-coat interface.

  5. Chemical vapor deposition of ceramic coatings on metals and ceramic fibers

    Science.gov (United States)

    Nable, Jun Co

    2005-07-01

    The research presented in this study consists of two major parts. The first part is about the development of ceramic coatings on metals by chemical vapor deposition (CVD) and metal-organic chemical vapor deposition (MOCVD). Ceramics such as Al2O3 and Cr2O3, are used as protective coatings for materials used at elevated temperatures (>700°C). These metal oxides either exhibit oxidation resistance or have been used as environmental bond coats. Conventional methods of coating by chemical vapor deposition requires deposition temperatures of >950°C which could damage the substrate material during the coating process. Lower deposition temperatures (400 to 600°C) by MOCVD of these metal oxides were successful on Ni metal substrates. Surface modification such as pre-oxidation and etching were also investigated. In addition, a novel approach for the CVD of TiN on metals was developed. This new approach utilizes ambient pressure conditions which lead to deposition temperatures of 800°C or lower compared to conventional CVD of TiN at 1000°C. Titanium nitride can be used as an abrasive and wear coating on cutting and grinding tools. This nitride can also serve as a diffusion coating in metals. The second major part of this research involves the synthesis of interfacial coatings on ceramic reinforcing fibers for ceramic matrix composites. Aluminum and chromium oxides were deposited onto SiC, and Al2O3-SiO 2 fibers by MOCVD. The effects of the interface coatings on the tensile strength of ceramic fibers are also discussed. New duplex interface coatings consisting of BN or TiN together with Al2O3 or ZrO 2 were also successfully deposited and evaluated on SiC fibers.

  6. Testing of porous SiC with dense coating under relevant conditions for Flow Channel Insert application

    Energy Technology Data Exchange (ETDEWEB)

    Ordás, N., E-mail: nordas@ceit.es [CEIT and Tecnun (University of Navarra), Manuel de Lardizábal 15, 20018 San Sebastián (Spain); Bereciartu, A.; García-Rosales, C. [CEIT and Tecnun (University of Navarra), Manuel de Lardizábal 15, 20018 San Sebastián (Spain); Moroño, A.; Malo, M.; Hodgson, E.R. [CIEMAT, Avenida Complutense 22, 28040 Madrid (Spain); Abellà, J.; Colominas, S. [Institut Químic de Sarrià, University Ramon Llull, Via Augusta 390, 08017 Barcelona (Spain); Sedano, L. [CIEMAT, Avenida Complutense 22, 28040 Madrid (Spain)

    2014-10-15

    Highlights: • Porous SiC coated by CVD with a dense coating was developed for Flow Channel Inserts (FCI) in dual-coolant blanket concept. • Porous SiC was obtained following the sacrificial template technique, using Al{sub 2}O{sub 3} and Y{sub 2}O{sub 3} as sintering additives. • Flexural strength, thermal and electrical conductivity, and microstructure of uncoated and coated porous SiC are presented. • Adhesion of coating to porous SiC and its corrosion behavior under Pb-17.5Li at 700 °C are shown. - Abstract: Thermally and electrically insulating porous SiC ceramics are attractive candidates for Flow Channel Inserts (FCI) in dual-coolant blanket concepts thanks to its relatively inexpensive manufacturing route. To prevent tritium permeation and corrosion by Pb-15.7 a dense coating has to be applied on the porous SiC. Despite not having structural function, FCI must exhibit sufficient mechanical strength to withstand strong thermal gradients and thermo-electrical stresses during operation. This work summarizes the results on the development of coated porous SiC for FCI. Porous SiC was obtained following the sacrificial template technique, using Al{sub 2}O{sub 3} and Y{sub 2}O{sub 3} as sintering additives and a carbonaceous phase as pore former. Sintering was performed in inert gas at 1850–1950 °C during 15 min to 3 h, followed by oxidation at 650 °C to eliminate the carbonaceous phase. The most promising bulk materials were coated with a ∼30 μm thick dense SiC by CVD. Results on porosity, bending tests, thermal and electrical conductivity are presented. The microstructure of the coating, its adhesion to the porous SiC and its corrosion behavior under Pb-17.5Li are also shown.

  7. Dense Nanostructured t-ZrO2 Coatings at Low Temperatures via Modified Emulsion Precipitation

    NARCIS (Netherlands)

    Woudenberg, F.C.M.; Sager, W.F.C.; Sibelt, N.G.M.; Verweij, H.

    2001-01-01

    Nanostructured coatings on metals, plastics, and textiles have numerous applications, for example, as antifogging and self-cleaning coatings as well as protective coatings against corrosion, heat, or wear. Here the preparation at low temperature of dense nanostructured tetragonal ZrO2 coatings via a

  8. Tough ceramic coatings: Carbon nanotube reinforced silica sol-gel

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, A.J., E-mail: antoniojulio.lopez@urjc.es [Dept. de Ciencia e Ingenieria de Materiales, ESCET, Universidad Rey Juan Carlos, C/Tulipan s/n, Mostoles 28933, Madrid (Spain); Rico, A.; Rodriguez, J.; Rams, J. [Dept. de Ciencia e Ingenieria de Materiales, ESCET, Universidad Rey Juan Carlos, C/Tulipan s/n, Mostoles 28933, Madrid (Spain)

    2010-08-15

    Silica coatings reinforced with carbon nanotubes were produced via sol-gel route using two mixing techniques of the sol-gel precursors, mechanical and ultrasonic mixing, and dip-coating as deposition process on magnesium alloy substrates. Effective incorporation and distribution of 0.1 wt.% of carbon nanotubes in the amorphous silica matrix of the coatings were achieved using both techniques. Fabrication procedure determines the morphological aspects of the coating. Only mechanical mixing process produced coatings dense and free of defects. Nanoindentation technique was used to examine the influence of the fabrication process in the mechanical features of the final coatings, i.e. indentation fracture toughness, Young's modulus and hardness. A maximum toughening effect of about 24% was achieved in silica coatings reinforced with carbon nanotubes produced by the mechanical mixing route. Scanning electron microscopy investigation revealed that the toughening of these reinforced coatings was mainly due to bridging effect of the reinforcement.

  9. Advanced ceramic coating development for industrial/utility gas turbines

    Science.gov (United States)

    Vogan, J. W.; Stetson, A. R.

    1982-01-01

    A program was conducted with the objective of developing advanced thermal barrier coating (TBC) systems. Coating application was by plasma spray. Duplex, triplex and graded coatings were tested. Coating systems incorporated both NiCrAly and CoCrAly bond coats. Four ceramic overlays were tested: ZrO2.82O3; CaO.TiO2; 2CaO.SiO2; and MgO.Al2O3. The best overall results were obtained with a CaO.TiO2 coating applied to a NiCrAly bond coat. This coating was less sensitive than the ZrO2.8Y2O3 coating to process variables and part geometry. Testing with fuels contaminated with compounds containing sulfur, phosphorus and alkali metals showed the zirconia coatings were destabilized. The calcium titanate coatings were not affected by these contaminants. However, when fuels were used containing 50 ppm of vanadium and 150 ppm of magnesium, heavy deposits were formed on the test specimens and combustor components that required frequent cleaning of the test rig. During the program Mars engine first-stage turbine blades were coated and installed for an engine cyclic endurance run with the zirconia, calcium titanate, and calcium silicate coatings. Heavy spalling developed with the calcium silicate system. The zirconia and calcium titanate systems survived the full test duration. It was concluded that these two TBC's showed potential for application in gas turbines.

  10. Experience with metal/ceramic coating in stationary gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Osyka, A.S. [State Area Power Station N3 of Mosenergo (GRES-3), Electrogorsk (Russian Federation); Rybnikov, A.I. [Polzunov Central Boiler and Turbine Inst., St. Petersburg (Russian Federation); Leontiev, S.A. [Leningradsky Metallitchesky Zavod, (LMZ), St. Petersburg (Russian Federation); Nikitin, N.V. [Ivanovo State Area Power Station, Komsomolsk (Russian Federation); Malashenko, I.S. [E.O. Paton Electric Welding Inst., Kiev (Ukraine)

    1995-11-01

    The uncooled rotating blades of the high pressure turbine (HPT) and of the low pressure turbine (LPT) of the peak load power gas turbine GT-100 are protected with electron-beam physically vapour deposited CoCrAlY coatings. Owing to low-temperature hot corrosion leakage, corrosion failure is observed. In order to improve the corrosion resistance, yttria stabilized zirconia (YSZ)/CoCrAlY coatings with a ceramic layer thickness of 50-70 {mu}m have been developed. The maximum service life of blades with the YSZ/CoCrAlY coatings has exceeded 939 h with 253 starts. Study of the YSZ/CoCrAlY coated blades after different service periods (from 306 to 939 h) showed different conditions of the ceramic layer: without any kind of damage, with small local damage, and with large-area spalling. (orig.)

  11. Adhesive strength and structure of micro-arc oxidation ceramic coatings grown in-situ on LY12 aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    WU Zhen-dong; JIANG Zhao-hua; YAO Zhong-ping

    2006-01-01

    The ceramic coatings containing zirconium dioxide were grown in-situ on LY12 aluminium alloy by micro-arc oxidation in mixed zirconate and phosphate solution. The phase composition and morphology of the coatings were studied by XRD and SEM.The adhesive strength of ceramic coatings was assessed by thermal shock test and tensile test. The results show that the coating is composed of m-ZrO2, t-ZrO2, and a little γ-Al2O3. Along the section of the coating, t-ZrO2 is more onboth sides than that in the middle, while m-ZrO2 is more in the middle than that on both sides. Meantime the coating is also composed of a dense layer and a loose layer. The coating has excellent thermal shock resistance under 550 ℃ and 600 ℃. And tensile tests show the adhesive strength of the dense layer of the coating with the substrate is more than 17.5 MPa.

  12. Summary of workshop on ceramic composite interface coatings

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-08-01

    Commercialization of fiber-reinforced composites has been limited because of the stability of the interface coatings that control the mechanical properties of the composites. Typical materials are currently manufactured with pyrolytic carbon interface coatings that perform well in inert atmospheres or when stresses are kept very low (<70 MPa). Unfortunately, carbon coatings are not stable at high temperatures in air or oxidizing conditions which results in degradation of the mechanical properties of the composites. The problem of oxidation resistant interface coatings is not unique to the Fossil Program. Such coatings are also a concern to the United States Air Force, the Continuous Fiber-reinforced Ceramic Composites Program, the Fusion Energy Materials Program, and to the European Community. This workshop was organized to compare and discuss the need for and development of oxidation-resistant interface coatings in each of these programs.

  13. DEVELOPMENT OF COMPLEX EQUIPMENT FOR PLASMA SPRAY CERAMIC COATINGS

    Directory of Open Access Journals (Sweden)

    V. V. Okovity

    2017-01-01

    Full Text Available Develop a set equipment for plasma forming ceramic coatings. The article presents characteristics and parameters of the developed complex equipment for formation of plasma ceramic coatings as well as results of its testing. Methods of research is based on studies of structural elements composite plasma coatings system ZrO2 – Y2O3  obtained  using  developed complex equipment. One of the most effective ways to protect the components from high temperature corrosion and oxidation is formation on the surface of plasma thermal barrier coatings. For thermal barrier coating has very strict requirements: сharacterized by a smooth change of physico-mechanical properties (porosity, microhardness, elastic modulus in the cross section of the metal substrate to the outer ceramic layer; to withstand multiple cycles of thermal cycling from room temperature to the operating temperature; to maintain gastightness under operating conditions and thus ensure a sufficiently high level of adhesive strength. For realization of new technological schemes applying thermal barrier coatings with high operational characteristics was developed, patented and manufactured a range of new equipment. The experiments show that authors developed PBG-1 plasmatron and powder feeder PPBG-04 have at least 2–3 times the service life during the deposition of ceramic materials compared to the standard equipment of the company "Plasma-Technik", by changing the structure of the cathode-anode plasma torch assembly and construction of the delivery unit of the feeder to facilitate the uniform supply of the powder into the plasma jet and the best of his penetration. The result is better plasma coatings with improved operational characteristics: adhesion strength is increased to 1.3–2 times, material utilization in 1.5–1.6 times microhardness 1.2–1.4 times the porosity is reduced by 2–2.5 times.

  14. Polymer Coating for Immobilizing Soluble Ions in a Phosphate Ceramic Product

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Dileep; Wagh, Arun S.; Patel, Kartikey D.

    1999-05-05

    A polymer coating is applied to the surface of a phosphate ceramic composite to effectively immobilize soluble salt anions encapsulated within the phosphate ceramic composite. The polymer coating is made from ceramic materials, including at least one inorganic metal compound, that wet and adhere to the surface structure of the phosphate ceramic composite, thereby isolating the soluble salt anions from the environment and ensuring long-term integrity of the phosphate ceramic composite.

  15. Selected Properties Of Thermally Sprayed Oxide Ceramic Coatings

    Directory of Open Access Journals (Sweden)

    Czupryński A.

    2015-09-01

    Full Text Available The article presents the results of the study on exploitation properties of flame sprayed ceramic coatings produced by oxide ceramic material in the form of powder on the aluminum oxide Al2O3 matrix with 3% titanium oxide TiO2 addition and also on the zirconium oxide (ZrO2 matrix with 30% calcium oxide (CaO on the substrate of unalloyed structural steel of S235JR grade. As a primer powder, metallic powder on the base of Ni-Al-Mo has been applied. Plates with dimensions of 5×200×300 mm and also front surfaces of ∅40×50 mm cylinders have been flame sprayed. Spraying of primer coating has been done using RotoTec 80 torch and external specific coating has been done with CastoDyn DS 8000 torch. Investigations of coating properties are based on metallography tests, phase composition research, measurement of microhardness, coating adhesion to the ground research (acc. to EN 582:1996 standard, abrasive wear resistance (acc. to ASTM G65 standard and erosion wear resistance (acc. to ASTM G76-95 standard and thermal stroke study. Performed tests have shown that the flame spraying with 97%Al2O3 powder containing 3% TiO2 and also by the powder based on zirconium oxide (ZrO2 containing 30% calcium oxide (CaO performed in a wide range of technological parameters allow to obtain high quality ceramic coatings with thickness up to ca. 500 μm on a steel substrate. The primer coating sprayed with the Ni-Al-Mo powder to the steel substrate and external coatings sprayed has the of mechanical bonding character. The coatings are characterized by high adhesion to the substrate and also high erosion and abrasive wear resistance and the resistance for cyclic thermal stroke.

  16. Dental ceramics coated with bioactive glass: Surface changes after exposure in a simulated body fluid under static and dynamic conditions

    Science.gov (United States)

    Papadopoulou, L.; Kontonasaki, E.; Zorba, T.; Chatzistavrou, X.; Pavlidou, E.; Paraskevopoulos, K.; Sklavounos, S.; Koidis, P.

    2003-07-01

    Bioactive materials develop a strong bond with living tissues through a carbonate-containing hydroxyapatite layer, similar to that of bone. The fabrication of a thin bioactive glass coating on dental ceramics used in metal-ceramic restorations, could provide a bioactive surface, which in combination with a tissue regenerative technique could lead to periodontal tissues attachment. The aim of this study was the in vitro investigation of the surface structure changes of dental ceramics used in metal-ceramic restorations, coated with a bioactive glass heat-treated at 950 °C, after exposure in a simulated body fluid (SBF) under two different soaking conditions. Coating of dental ceramics with a bioactive glass resulted in the formation of a stable and well bonded with the ceramic substrate thin layer. The growth of a well-attached carbonate apatite layer on their surface after immersion in a simulated body fluid is well evidenced under both experimental conditions, although in static environment the rate of apatite growth is constant and the grown layers seem to be more dense and compact compared with the respective layers observed on specimens under dynamic conditions.

  17. Dense ceramic catalytic membranes and membrane reactors for energy and environmental applications.

    Science.gov (United States)

    Dong, Xueliang; Jin, Wanqin; Xu, Nanping; Li, Kang

    2011-10-21

    Catalytic membrane reactors which carry out separation and reaction in a single unit are expected to be a promising approach to achieve green and sustainable chemistry with less energy consumption and lower pollution. This article presents a review of the recent progress of dense ceramic catalytic membranes and membrane reactors, and their potential applications in energy and environmental areas. A basic knowledge of catalytic membranes and membrane reactors is first introduced briefly, followed by a short discussion on the membrane materials including their structures, composition and strategies for material development. The configuration of catalytic membranes, the design of membrane reaction processes and the high temperature sealing are also discussed. The performance of catalytic membrane reactors for energy and environmental applications are summarized and typical catalytic membrane reaction processes are presented and discussed. Finally, current challenges and difficulties related to the industrialization of dense ceramic membrane reactors are addressed and possible future research is also outlined.

  18. Oxidation-resistant interfacial coatings for continuous fiber ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Stinton, D.P.; Besmann, T.M.; Bleier, A. [Oak Ridge National Lab., TN (United States); Shanmugham, S.; Liaw, P.K. [Univ. of Tennessee, Knoxville, TN (United States)

    1995-08-01

    Continuous fiber ceramic composites mechanical behavior are influenced by the bonding characteristics between the fiber and the matrix. Finite modeling studies suggest that a low-modulus interfacial coating material will be effective in reducing the residual thermal stresses that are generated upon cooling from processing temperatures. Nicalon{trademark}/SiC composites with carbon, alumina and mullite interfacial coatings were fabricated with the SiC matrix deposited using a forced-flow, thermal gradient chemical vapor infiltration process. Composites with mullite interfacial coatings exhibited considerable fiber pull-out even after oxidation and have potential as a composite system.

  19. Fabrication and characterization of dense zirconia and zirconia-silica ceramic nanofibers.

    Science.gov (United States)

    Xu, Xiaoming; Guo, Guangqing; Fan, Yuwei

    2010-09-01

    The objective of this study was to prepare dense zirconia-yttria (ZY), zirconia-silica (ZS) and zirconia-yttria-silica (ZYS) nanofibers as reinforcing elements for dental composites. Zirconium (IV) propoxide, yttrium nitrate hexahydrate, and tetraethyl orthosilicate (TEOS) were used as precursors for the preparation of zirconia, yttria, and silica sols. A small amount (1-1.5 wt%) of polyethylene oxide (PEO) was used as a carry polymer. The sols were preheated at 70 degrees C before electrospinning and their viscosity was measured with a viscometer at different heating time. The gel point was determined by viscosity-time (eta-t) curve. The ZY, ZS and ZYS gel nanofibers were prepared using a special reactive electrospinning device under the conditions near the gel point. The as-prepared gel nanofibers had diameters between 200 and 400 nm. Dense (nonporous) ceramic nanofibers of zirconia-yttria (96/4), zirconia-silica (80/20) and zirconia-yttria-silica (76.8/3.2/20) with diameter of 100-300 nm were obtained by subsequent calcinations at different temperatures. The gel and ceramic nanofibers obtained were characterized by scanning electron microscope (SEM), high-resolution field-emission scanning electron microscope (FE-SEM), thermogravimetric analyzer (TGA), differential scanning calorimeter (DSC), Fourier transform infrared spectrometer (FT-IR), and X-ray diffraction (XRD). SEM micrograph revealed that ceramic ZY nanofibers had grained structure, while ceramic ZS and ZYS nanofibers had smooth surfaces, both showing no visible porosity under FE-SEM. Complete removal of the polymer PEO was confirmed by TGA/DSC and FT-IR. The formation of tetragonal phase of zirconia and amorphous silica was proved by XRD. In conclusion, dense zirconia-based ceramic nanofibers can be fabricated using the new reactive sol-gel electrospinning technology with minimum organic polymer additives.

  20. Hierarchical Formation of Intrasplat Cracks in Thermal Spray Ceramic Coatings

    Science.gov (United States)

    Chen, Lin; Yang, Guan-Jun; Li, Cheng-Xin; Li, Chang-Jiu

    2016-06-01

    Intrasplat cracks, an essential feature of thermally sprayed ceramic coatings, play important roles in determining coating properties. However, final intrasplat crack patterns are always considered to be disordered and irregular, resulting from random cracking during splat cooling, since the detailed formation process of intrasplat cracks has scarcely been considered. In the present study, the primary formation mechanism for intrasplat cracking was explored based on both experimental observations and mechanical analysis. The results show that the intrasplat crack pattern in thermally sprayed ceramic splats presents a hierarchical structure with four sides and six neighbors, indicating that intrasplat crack patterns arise from successive domain divisions due to sequential cracking during splat cooling. The driving forces for intrasplat cracking are discussed, and the experimental data quantitatively agree well with theoretical results. This will provide insight for further coating structure designs and tailoring by tuning of intrasplat cracks.

  1. In situ measurement of ceramic vacuum chamber conductive coating quality

    Energy Technology Data Exchange (ETDEWEB)

    Doose, C.; Harkay, K.; Kim, S.; Milton, S.

    1997-08-01

    A method for measuring the relative surface resistivity and quality of conductive coatings on ceramic vacuum chambers was developed. This method is unique in that it allows one to test the coating even after the ceramic chamber is installed in the accelerator and under vacuum; furthermore, the measurement provides a localized surface reading of the coating conductance. The method uses a magnetic probe is calibrated using the measured DC end-to-end resistance of the tube under test and by comparison to a high quality test surface. The measurement method has also been verified by comparison to high frequency impedance measurements. A detailed description, results, and sensitivity of the technique are given here.

  2. Cold Spray Coating of Submicronic Ceramic Particles on Poly(vinyl alcohol) in Dry and Hydrogel States

    Science.gov (United States)

    Moreau, David; Borit, François; Corté, Laurent; Guipont, Vincent

    2017-06-01

    We report an approach using cold spray technology to coat poly(vinyl alcohol) (PVA) in polymer and hydrogel states with hydroxyapatite (HA). Using porous aggregated HA powder, we hypothesized that fragmentation of the powder upon cold spray could lead to formation of a ceramic coating on the surface of the PVA substrate. However, direct spraying of this powder led to complete destruction of the swollen PVA hydrogel substrate. As an alternative, HA coatings were successfully produced by spraying onto dry PVA substrates prior to swelling in water. Dense homogeneous HA coatings composed of submicron particles were obtained using rather low-energy spraying parameters (temperature 200-250 °C, pressure 1-3 MPa). Coated PVA substrates could swell in water without removal of the ceramic layer to form HA-coated hydrogels. Microscopic observations and in situ measurements were used to explain how local heating and impact of sprayed aggregates induced surface roughening and strong binding of HA particles to the molten PVA substrate. Such an approach could lead to design of ceramic coatings whose roughness and crystallinity can be finely adjusted to improve interfacing with biological tissues.

  3. Preparation and characterizations of bioglass ceramic cement/Ca-P coating on pure magnesium for biomedical applications.

    Science.gov (United States)

    Zhang, Xue; Li, Xiao-Wu; Li, Ji-Guang; Sun, Xu-Dong

    2014-01-08

    Magnesium has been recently recognized as a biodegradable metal for bone substitute applications. In order to improve the biocompatibility and osteointegration of pure Mg, two kinds of coatings, i.e., the Ca-P coating and bioglass ceramic cement (BGCC)/Ca-P coating, were prepared on the pure Mg ribbons in the present work. The Ca-P coating was obtained by aqueous solution method. Subsequently, Ca-P coated Mg was immersed into the BGCC slurry, which was prepared by the mix of SiO2-CaO-P2O5 bioglass ceramic (BGC) powders and phosphate liquid with a liquid-to-solid ratio (L/S) of 1.6, to obtain BGCC/Ca-P coating by a dipping-pulling method. The microstructures, morphologies, and compositions of these coatings have been characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS). The effect of these coatings on the mineralization activity of pure Mg has been investigated. The results indicated that both the Ca-P coating and BGCC/Ca-P coating could promote the nucleation of osteoconductive minerals, i.e., bone-like apatite, and the hydroxyapatite (HA) layer formed on the surface of the BGCC/Ca-P coating is obviously more dense, thick, and stable than that formed on the Ca-P coating after immersion in SBF solution for 15 days. The potentiodynamic polarization test indicated that the corrosion current density of the BGCC/Ca-P coated Mg is obviously lower than that of the Ca-P coating and 10 times lower than that of uncoated Mg. These results demonstrated that the BGCC/Ca-P coating can increase significantly the corrosion resistance of Mg and introduce a high biocompatibility of the bone-Mg substrate interface. In summary, the newly developed BGCC/Ca-P coated Mg has a good potential for biomedical applications.

  4. Glass-ceramic coated Mg-Ca alloys for biomedical implant applications.

    Science.gov (United States)

    Rau, J V; Antoniac, I; Fosca, M; De Bonis, A; Blajan, A I; Cotrut, C; Graziani, V; Curcio, M; Cricenti, A; Niculescu, M; Ortenzi, M; Teghil, R

    2016-07-01

    Biodegradable metals and alloys are promising candidates for biomedical bone implant applications. However, due to the high rate of their biodegradation in human body environment, they should be coated with less reactive materials, such, for example, as bioactive glasses or glass-ceramics. Fort this scope, RKKP composition glass-ceramic coatings have been deposited on Mg-Ca(1.4wt%) alloy substrates by Pulsed Laser Deposition method, and their properties have been characterized by a number of techniques. The prepared coatings consist of hydroxyapatite and wollastonite phases, having composition close to that of the bulk target material used for depositions. The 100μm thick films are characterized by dense, compact and rough morphology. They are composed of a glassy matrix with various size (from micro- to nano-) granular inclusions. The average surface roughness is about 295±30nm due to the contribution of micrometric aggregates, while the roughness of the fine-texture particulates is approximately 47±4nm. The results of the electrochemical corrosion evaluation tests evidence that the RKKP coating improves the corrosion resistance of the Mg-Ca (1.4wt%) alloy in Simulated Body Fluid.

  5. Ceramic coatings of LA141 alloy formed by plasma electrolytic oxidation for corrosion protection.

    Science.gov (United States)

    Li, Zhijun; Yuan, Yi; Sun, Pengpeng; Jing, Xiaoyan

    2011-09-01

    Superlight Mg-Li alloy is a promising structural materials in aerospace, automobile, and electronics because of its excellent properties such as low density, high ductility, superior strength-to-weight ratio, and good damping ability. The fabrication of compact plasma electrolytic oxidation coatings with excellent corrosion resistance is valuable for the widespread application of Mg-Li alloy. Here we present a ceramic coating on the surface of Mg-14Li-1Al (LA141) alloy for corrosion protection via plasma electrolytic oxidation (PEO) in an alkaline silicate electrolyte with tungstate as an additive. X-ray photoelectron spectroscopy and thin film-X-ray diffraction analysis of coatings show that the surface coating is mainly comprised of Mg(2)SiO(4), MgO and WO(3). Scanning electron microscopy observations have revealed that the dense and compact coating formed in the presence of tungstate has less structural imperfections in comparison to the control one fabricated without use of tungstate. The effect of oxidation time on the morphology and phase composition of coatings is also examined in detail.

  6. Glass/ceramic coatings for implants

    Science.gov (United States)

    Tomsia, Antoni P.; Saiz, Eduardo; Gomez-Vega, Jose M.; Marshall, Sally J.; Marshall, Grayson W.

    2011-09-06

    Glass coatings on metals including Ti, Ti6A14V and CrCo were prepared for use as implants. The composition of the glasses was tailored to match the thermal expansion of the substrate metal. By controlling the firing atmosphere, time, and temperature, it was possible to control the reactivity between the glass and the alloy and to fabricate coatings (25-150 .mu.m thick) with excellent adhesion to the substrate. The optimum firing temperatures ranged between 800 and 840.degree. C. at times up to 1 min in air or 15 min in N.sub.2. The same basic technique was used to create multilayered coatings with concentration gradients of hydroxyapatite (HA) particles and SiO.sub.2.

  7. Advanced Environmental Barrier Coatings Development for Si-Based Ceramics

    Science.gov (United States)

    Zhu, Dong-Ming; Choi, R. Sung; Robinson, Raymond C.; Lee, Kang N.; Bhatt, Ramakrishna T.; Miller, Robert A.

    2005-01-01

    Advanced environmental barrier coating concepts based on multi-component HfO2 (ZrO2) and modified mullite systems are developed for monolithic Si3N4 and SiC/SiC ceramic matrix composite (CMC) applications. Comprehensive testing approaches were established using the water vapor cyclic furnace, high pressure burner rig and laser heat flux steam rig to evaluate the coating water vapor stability, cyclic durability, radiation and erosion resistance under simulated engine environments. Test results demonstrated the feasibility and durability of the environmental barrier coating systems for 2700 to 3000 F monolithic Si3N4 and SiC/SiC CMC component applications. The high-temperature-capable environmental barrier coating systems are being further developed and optimized in collaboration with engine companies for advanced turbine engine applications.

  8. Fracture Behavior Characteristic of Ceramic Reinforced Metal-Base Coatings

    Institute of Scientific and Technical Information of China (English)

    MA Chong; JING Hongyang; XU Lianyong

    2009-01-01

    The fracture behavior of a ceramic reinforced metal-base coating prepared by high velocity arc spraying (HVAS)technology in three-point bending test was studied.Moreover,finite element analysis(FEA)was adopted to analyze the stress distribution in the crack front.It can be found that the crack norrnal to the interface in the coatings occurred at the location where a fixed moment of force was reached.So the critical moment can be taken as thecoating cracking criterion,which was confirmed by FEA results.In addition,the stress levels at three different locations where cracks occurred near the interface are almost the same.The results will provide reference for the design of coatings and the structure integrity evaluation of coating/substrate systems.

  9. Plasma-sprayed ceramic coatings for protection against molten metal.

    Energy Technology Data Exchange (ETDEWEB)

    Hollis, K. J. (Kendall J.); Peters, M. I. (Maria I.); Bartram, B. D. (Brian D.)

    2002-01-01

    Molten metal environments pose a special demand on materials due to the high temperature corrosion effects and thermal expansion mismatch induced stress effects. A solution that has been successfully employed is the use of a base material for the mechanical strength and a coating material for the chemical compatibility with the molten metal. The work described here used such an approach coating tungsten rods with aluminum oxide, yttria-stabilized zirconia, yttrium oxide, and erbium oxide deposited by atmospheric plasma spraying. The ceramic materials were deposited under varying conditions to produce different structures. Measurement of particle characteristics was performed to correlate to material properties. The coatings were tested in a thermal cycling environment to simulate the metal melting cycle expected in service. Results of the testing indicate the effect of material composition and spray conditions on the thermal cycle crack resistance of the coatings.

  10. Glass-ceramic coating material for the CO2 laser based sintering of thin films as caries and erosion protection.

    Science.gov (United States)

    Bilandžić, Marin Dean; Wollgarten, Susanne; Stollenwerk, Jochen; Poprawe, Reinhart; Esteves-Oliveira, Marcella; Fischer, Horst

    2017-09-01

    The established method of fissure-sealing using polymeric coating materials exhibits limitations on the long-term. Here, we present a novel technique with the potential to protect susceptible teeth against caries and erosion. We hypothesized that a tailored glass-ceramic material could be sprayed onto enamel-like substrates to create superior adhesion properties after sintering by a CO2 laser beam. A powdered dental glass-ceramic material from the system SiO2-Na2O-K2O-CaO-Al2O3-MgO was adjusted with individual properties suitable for a spray coating process. The material was characterized using X-ray fluorescence analysis (XRF), heating microscopy, dilatometry, scanning electron microscopy (SEM), grain size analysis, biaxial flexural strength measurements, fourier transform infrared spectroscopy (FTIR), and gas pycnometry. Three different groups of samples (each n=10) where prepared: Group A, powder pressed glass-ceramic coating material; Group B, sintered hydroxyapatite specimens; and Group C, enamel specimens (prepared from bovine teeth). Group B and C where spray coated with glass-ceramic powder. All specimens were heat treated using a CO2 laser beam process. Cross-sections of the laser-sintered specimens were analyzed using laser scanning microscopy (LSM), energy dispersive X-ray analysis (EDX), and SEM. The developed glass-ceramic material (grain size d50=13.1mm, coefficient of thermal expansion (CTE)=13.310(-6)/K) could be spray coated on all tested substrates (mean thickness=160μm). FTIR analysis confirmed an absorption of the laser energy up to 95%. The powdered glass-ceramic material was successfully densely sintered in all sample groups. The coating interface investigation by SEM and EDX proved atomic diffusion and adhesion of the glass-ceramic material to hydroxyapatite and to dental enamel. A glass-ceramic material with suitable absorption properties was successfully sprayed and laser-sintered in thin films on hydroxyapatite as well as on bovine enamel

  11. Lower-Conductivity Ceramic Materials for Thermal-Barrier Coatings

    Science.gov (United States)

    Bansal, Narottam P.; Zhu, Dongming

    2006-01-01

    Doped pyrochlore oxides of a type described below are under consideration as alternative materials for high-temperature thermal-barrier coatings (TBCs). In comparison with partially-yttria-stabilized zirconia (YSZ), which is the state-of-the-art TBC material now in commercial use, these doped pyrochlore oxides exhibit lower thermal conductivities, which could be exploited to obtain the following advantages: For a given difference in temperature between an outer coating surface and the coating/substrate interface, the coating could be thinner. Reductions in coating thicknesses could translate to reductions in weight of hot-section components of turbine engines (e.g., combustor liners, blades, and vanes) to which TBCs are typically applied. For a given coating thickness, the difference in temperature between the outer coating surface and the coating/substrate interface could be greater. For turbine engines, this could translate to higher operating temperatures, with consequent increases in efficiency and reductions in polluting emissions. TBCs are needed because the temperatures in some turbine-engine hot sections exceed the maximum temperatures that the substrate materials (superalloys, Si-based ceramics, and others) can withstand. YSZ TBCs are applied to engine components as thin layers by plasma spraying or electron-beam physical vapor deposition. During operation at higher temperatures, YSZ layers undergo sintering, which increases their thermal conductivities and thereby renders them less effective as TBCs. Moreover, the sintered YSZ TBCs are less tolerant of stress and strain and, hence, are less durable.

  12. Evaluation of interface reactions in thermal barrier ceramic coatings

    Energy Technology Data Exchange (ETDEWEB)

    Celik, E.; Avci, E.; Yilmaz, F. [Sakarya Univ. (Turkey). Eng. Fac.

    1997-12-01

    In this study, the interface reactions in thermal barrier ceramic coatings (TBCs) on AISI 304L stainless steel substrates were investigated. The plasma-spray technique was employed to deposit metallic and ceramic powders such as MgZrO{sub 3}, NiAl+MgZrO{sub 3} and NiCrAl+MgZrO{sub 3} on the substrate. The porosity of these coatings, measured by an optical method, was found to be between 6 and 9%. Oxidation tests were carried out to evaluate the interface reactions in TBCs at temperatures of 800, 900 and 1000 C. The microstructures of the powders, coatings and oxidized coatings were examined by means of an optical microscope and X-ray diffractometry. The results show that the oxidation kinetics depend strongly on oxide layer thickness, temperature, duration of oxidation and composition of the bond coat. It was also observed that the oxidation rate changed with temperature was initially linear and then exponential. (orig.) 14 refs.

  13. New ceramic coating technique using laser spraying process

    Science.gov (United States)

    Tsukamoto, Koichi; Yanagisawa, Takeshi; Uchiyama, Futodhi; Obara, Akira; Okutomi, Mamoru; Kimura, Shinji; Yamada, Akimasa; Shen, Hong L.; Wang, Zhongcheng; Shen, Qinwo; Chatterjee, Udit; Bhar, Gopal C.

    1998-08-01

    A new ceramic coating technique using a CO2 laser has been developed. A high power density laser beam passes near the substrate. Coating materials are supplied by an extra-high accuracy powder supply device and pass across the laser beam. The coating materials are melted in the laser beam and deposited on the substrate surface. A YSZ (Yttria Stabilized Zirconia) layer and a LaCoO3 layer are made for high temperature solid oxide fuel cells. The crystal structures of the coated layers are the same as that of the original coating materials. Superconducting BPSCCO ceramic films are also made with this process. The films show super-conductivity with Tc at 81 K. The Jc of the specimen is 440 A/cm2 at 77 K. We can easily handle and arrange not only metal but also refractory materials. By adopting a multi-axis robot and a surface treatment laser technique, the laser spraying method described here makes it possible to produce highly functional and three dimensional parts of devices directly from raw powder materials. Thus the proposed method will open the path to an unexplored field of key production technology.

  14. Plasma Sprayed Dense MgO-Y2O3 Nanocomposite Coatings Using Sol-Gel Combustion Synthesized Powder

    Science.gov (United States)

    Wang, Jiwen; Jordan, Eric H.; Gell, Maurice

    2010-09-01

    MgO-Y2O3 nanostructured composite powder (volume ratio of 50:50) was synthesized by a sol-gel combustion process which generated crystal sizes in the 10-20 nm range. The MgO-Y2O3 nanopowder was plasma sprayed using a conventional, DC arc plasma spray system. X-ray diffraction analysis shows that the as-sprayed MgO-Y2O3 coating is composed of cubic MgO and Y2O3 phases and has ~95% density. Microstructure characterization by SEM reveals that the as-sprayed coating has fine grain sizes of 100-300 nm as a result of rapid solidification. The hardness of the coating, 7.5 ± 0.6 GPa, is higher than that of coarse-grained, dense MgO, and Y2O3 ceramics. This approach demonstrates the potential of plasma spray processes for making thick, dense MgO-Y2O3 nanocomposite performs for applications as durable, infrared windows.

  15. Synthesis of Dense, Fine-Grained YIG Ceramics by Two-Step Sintering

    Science.gov (United States)

    Li, X. X.; Zhou, J. J.; Deng, J. X.; Zheng, H.; Zheng, L.; Zheng, P.; Qin, H. B.

    2016-10-01

    A two-step sintering (TSS) process has been used to fabricate yttrium iron garnet (YIG) ceramics with high density and fine grain size. The densification, microstructure, and magnetic properties were investigated. The sample prepared by the TSS process with first-step sintering temperature ( T 1) of 1350°C, second-step sintering temperature ( T 2) of 1300°C, and holding time of 18 h had density above 99% of theoretical and exhibited uniform microstructure with small average grain size (2.4 μm). The saturation magnetization ( M S) of this sample reached 27.4 emu/g. These results indicate that the TSS process can effectively suppress grain-boundary migration while maintaining active grain-boundary diffusion to obtain dense, fine-grained YIG ceramics with appropriate magnetic properties.

  16. Spin coating of passive electroactive ceramic devices

    CERN Document Server

    Carson, E

    2001-01-01

    ferrite inductor paste materials as powders before and after thermal processing in the range 150, 500, 850 and 1150 deg C indicates a high carbon content in the surface region. By comparison, spin coated layers of each of these systems on alumina substrates before and after heating in the same temperature range as that used for the residual powders, showed a marked decrease in the carbon content in the surface region. In addition, deposition of the dielectric onto a ferrite surface which itself had been spin coated on alumina indicated no merging of the different layers. Thermal processing of this bi-layer system up to 850 deg C provides evidence that there may be some channelling of the bismuth photoelectrons through suitably sized pores in the dielectric layer. The commercial doctor blading method has also been used to produce dielectric layers and these are shown to be somewhat different to those produced by spin coating. In particular, the doctor bladed material contains more carbonaceous material in the ...

  17. Dense ceramic membranes: A review of the state of the art

    Directory of Open Access Journals (Sweden)

    Kozhukharov, V.

    1999-02-01

    Full Text Available During the past several years the concepts of oxygen permeation through mixed valency ceramic membranes possess special interest. In this context, a classification and brief review of the major membrane ceramic materials will be presented. The focus will be on dense ceramic membranes as elements for advanced application. A discussion will be proposed for mixed conductor ceramics as perovskite ABO3 compounds. Dense membranes on perovskite base are the object of the present review and some details about processing and characterization of double (A- and B-site substituted La1-x Sr(BaxCo0.8Fe0.2O3-d perovskites will be presented.

    El concepto de permeación de oxígeno a través de membranas cerámicas de valencia mixta, ha venido adquiriendo especial relevancia a lo largo de los últimos años. En este contexto se hace se efectúa una clasificación y breve revisión de los materiales cerámicos más relevantes utilizados como membranas. En particular se orienta la descripción hacia las membranas cerámicas densas para aplicaciones avanzadas. Se propone un análisis de los conductores cerámicos mixtos, como los compuestos de tipo perovskita ABO3. Se realiza una revisión de los materiales de este tipo existentes, así como se describen algunos aspectos sobre el procesamiento y caracterización de las perovskitas tipo La1-x Sr(BaxCo0.8Fe0.2O3-d doblemente sustituidas (lugares A- y B-.

  18. Osteointegration of biomimetic apatite coating applied onto dense and porous metal implants in femurs of goats

    NARCIS (Netherlands)

    Barrère, F.; van der Valk, C.M.; Meijer, G.; Dalmeijer, R.A.J.; de Groot, K.; Layrolle, P.

    2003-01-01

    Biomimetic calcium phosphate (Ca-P) coatings were applied onto dense titanium alloy (Ti6Al4V) and porous tantalum (Ta) cylinders by immersion into simulated body fluid at 37 °C and then at 50 °C for 24 h. As a result, a homogeneous bone-like carbonated apatitic (BCA) coating, 30 m thick was deposite

  19. Oxidation resistant coatings for ceramic matrix composite components

    Energy Technology Data Exchange (ETDEWEB)

    Vaubert, V.M.; Stinton, D.P. [Oak Ridge National Lab., TN (United States); Hirschfeld, D.A. [New Mexico Inst. of Mining and Technology, Socorro, NM (United States). Dept. of Materials and Metallurgical Engineering

    1998-11-01

    Corrosion resistant Ca{sub 0.6}Mg{sub 0.4}Zr{sub 4}(PO{sub 4}){sub 6} (CMZP) and Ca{sub 0.5}Sr{sub 0.5}Zr{sub 4}(PO{sub 4}){sub 6} (CS-50) coatings for fiber-reinforced SiC-matrix composite heat exchanger tubes have been developed. Aqueous slurries of both oxides were prepared with high solids loading. One coating process consisted of dipping the samples in a slip. A tape casting process has also been created that produced relatively thin and dense coatings covering a large area. A processing technique was developed, utilizing a pre-sintering step, which produced coatings with minimal cracking.

  20. Development of adherent ceramic coatings to reduce contact stress damage of ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Wayne, S.F.; Selverian, J.H.; O' Neil, D. (GTE Labs., Inc., Waltham, MA (United States))

    1992-11-01

    Strongly adherent coatings were deposited on reaction bonded Si[sub 3]N[sub 4] (RBSN), sintered SiC (SSC), and HIP'ed Si[sub 3]N[sub 4] (HSN) and using a newly developed chemical vapor deposition (CVD) process. Performance of the coating was assessed by oxidation, strength and contact stress testing. A new method was developed to experimentally determine the strength and Weibull modulus of thin brittle films on ceramic substrates. A significant portion of the study was devoted to numerical modeling of the coatings in order to understand the contributions of residual stress as different coating materials and thicknesses were combined. Coating designs were further analyzed by simulating the crack growth behavior in multilayer films while accounting for the interface fracture mechanics. This work has shown that the Al[sub 2]0[sub 3+]ZrO[sub 2] composite coating developed in this program can provide resistance to oxidation and contact stress. Commercial application of the composite coating has been successfully demonstrated by useof the Al[sub 2]0[sub 3+]ZrO[sub 2] composite as a protective coating on a Si[sub 3]N[sub 4] cutting tool.

  1. Development of adherent ceramic coatings to reduce contact stress damage of ceramics. Final report: DOE/ORNL Ceramic Technology Project

    Energy Technology Data Exchange (ETDEWEB)

    Wayne, S.F.; Selverian, J.H.; O`Neil, D. [GTE Labs., Inc., Waltham, MA (United States)

    1992-11-01

    Strongly adherent coatings were deposited on reaction bonded Si{sub 3}N{sub 4} (RBSN), sintered SiC (SSC), and HIP`ed Si{sub 3}N{sub 4} (HSN) and using a newly developed chemical vapor deposition (CVD) process. Performance of the coating was assessed by oxidation, strength and contact stress testing. A new method was developed to experimentally determine the strength and Weibull modulus of thin brittle films on ceramic substrates. A significant portion of the study was devoted to numerical modeling of the coatings in order to understand the contributions of residual stress as different coating materials and thicknesses were combined. Coating designs were further analyzed by simulating the crack growth behavior in multilayer films while accounting for the interface fracture mechanics. This work has shown that the Al{sub 2}0{sub 3+}ZrO{sub 2} composite coating developed in this program can provide resistance to oxidation and contact stress. Commercial application of the composite coating has been successfully demonstrated by useof the Al{sub 2}0{sub 3+}ZrO{sub 2} composite as a protective coating on a Si{sub 3}N{sub 4} cutting tool.

  2. Development of Bioactive Ceramic Coating on Titanium Alloy substrate for Biomedical Application Using Dip Coating Method

    Science.gov (United States)

    Asmawi, R.; Ibrahim, M. H. I.; Amin, A. M.; Mustafa, N.; Noranai, Z.

    2017-08-01

    Bioactive apatite, such as hydroxyapatite ceramic (HA), [Ca10(PO4)6(OH)2] has been extensively investigated for biomedical applications due to its excellent biocompatibility and tissue bioactivity properties. Its bioactivity provides direct bonding to the bone tissue. Because of its similarity in chemical composition to the inorganic matrix of bone, HA is widely used as implant materials for bone. Unfortunately, because of its poor mechanical properties,. this bioactive material is not suitable for load bearing applications. In this study, by the assistance of dip-coating technique, HA coatings were deposited on titanium alloy substrates by employing hydrothermal derived HA powder. The produced coatings then were oven-dried at 130°C for 1 hour and calcined at various temperature over the range of 200-800°C for 1 hour. XRD measurement showed that HA was the only phase present in the coatings. However coatings calcined at 800°C comprised a mixture of HA and tri-calcium phosphate (TCP). FTIR measurement showed the existence of hydroxyl, phosphate, and carbonate bands. PO4 - band became sharper and narrower with the increased of calcination temperature. FESEM observation showed that the coating is polycrystalline with individual particles of nano to submicron size and has an average particle size of 35 nm. The thickness of the coating are direcly propotional with the viscosity of coating slurry. It was shown that the more viscous coating slurry would produce a thicker ceramic coating. Mechanical properties of the coating were measured in term of adhesion strength using a Micro Materials Nano Test microscratch testing machine. The result revealed that the coating had a good adhesion to the titanium alloy substrate.

  3. Microstructures and Composition of Ceramic Coatings on Aluminum Produced by Micro-Arc Oxidation

    Institute of Scientific and Technical Information of China (English)

    SHEN De-jiu; WANG Yu-lin; GU Wei-chao; XING Guang-zhong

    2004-01-01

    Microstructures and phase composition of the ceramic coatings formed on pure aluminum by heteropolar pulsed current ceramic synthesizing system for different periods were investigated by X-ray diffraction (XRD) and scanning electronic microscopy (SEM). Results show that the amount of the discharge channels in the ceramic coating sminish while the aperture largen in the micro-arc oxidation process, and the surface of the ceramic coatingmelted and solidified in the process.XRD studies of ceramic coatings deposited for different time show that these coatings consist mainly of α-Al2 O3, γ-Al2 O3 , θ-Al2 O3 and a little amorphous phase, and phase composition of compact and porous ceramic coatings don' t have much difference but have a little change of the content of α-Al2 O3 and amorphous phase.

  4. Current Issues with Environmental Barrier Coatings for Ceramics and Ceramic Composites

    Science.gov (United States)

    Lee, Kang N.

    2004-01-01

    The environmental barrier coating (EBC) for SiC/SiC ceramic matrix composites and Si3N4 ceramics is an emerging field as the application of silicon-based ceramics in the gas turbine engine hot section is on the horizon, both for aero and industrial gas turbines. EBC is an enabling technology for silicon-based ceramics because these materials without an EBC cannot be used in combustion environments due to rapid surface recession. Significant progress in EBC development has been made during the last decade through various government-sponsored programs. Current EBCs are based on silicon, mullite (3Al2O3-2SiO2) and BSAS (barium strontium aluminum silicate with celsian structure). Volatility of BSAS, BSAS-silica chemical reaction, and low melting point of silicon limit temperature capability of current EBCs to about 1350 C for long-term applications. There is a need for higher temperature EBCs as the temperature capability of silicon-based ceramics continue to increase. Therefore, research is underway to develop EBCs with improved temperature capability compared to current EBCs. The current status and issues with the advanced EBC development efforts will be discussed.

  5. Current Issues with Environmental Barrier Coatings for Ceramics and Ceramic Composites

    Science.gov (United States)

    Lee, Kang N.

    2004-01-01

    The environmental barrier coating (EBC) for SiC/SiC ceramic matrix composites and Si3N4 ceramics is an emerging field as the application of silicon-based ceramics in the gas turbine engine hot section is on the horizon, both for aero and industrial gas turbines. EBC is an enabling technology for silicon-based ceramics because these materials without an EBC cannot be used in combustion environments due to rapid surface recession. Significant progress in EBC development has been made during the last decade through various government-sponsored programs. Current EBCs are based on silicon, mullite (3Al2O3-2SiO2) and BSAS (barium strontium aluminum silicate with celsian structure). Volatility of BSAS, BSAS-silica chemical reaction, and low melting point of silicon limit temperature capability of current EBCs to about 1350 C for long-term applications. There is a need for higher temperature EBCs as the temperature capability of silicon-based ceramics continue to increase. Therefore, research is underway to develop EBCs with improved temperature capability compared to current EBCs. The current status and issues with the advanced EBC development efforts will be discussed.

  6. Fire resistance properties of ceramic wool fiber reinforced intumescent coatings

    Energy Technology Data Exchange (ETDEWEB)

    Amir, N., E-mail: norlailiamir@petronas.com.my; Othman, W. M. S. W., E-mail: wamosa@gmail.com; Ahmad, F., E-mail: faizahmad@petronas.com.my [Mechanical Engineering Department, Universiti Teknologi PETRONAS Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia)

    2015-07-22

    This research studied the effects of varied weight percentage and length of ceramic wool fiber (CWF) reinforcement to fire retardant performance of epoxy-based intumescent coating. Ten formulations were developed using ammonium polyphosphate (APP), expandable graphite (EG), melamine (MEL) and boric acid (BA). The mixing was conducted in two stages; powdered materials were grinded in Rocklabs mortar grinder and epoxy-mixed using Caframo mixer at low speed mixing. The samples were applied on mild steel substrate and exposed to 500°C heat inside Carbolite electric furnace. The char expansion and its physical properties were observed. Scanning electron microscopy (SEM) analyses were conducted to inspect the fiber dispersion, fiber condition and the cell structure of both coatings and chars produced. Thermogravimetric analyses (TGA) were conducted to study the thermal properties of the coating such as degradation temperature and residual weight. Fire retardant performance was determined by measuring backside temperature of substrate in 1-hour, 1000°C Bunsen burner test according to UL 1709 fire regime. The results showed that intumescent coating reinforced with CWF produced better fire resistance performance. When compared to unreinforced coating, formulation S6-15 significantly reduced steel temperature at approximately 34.7% to around 175°C. However, higher fiber weight percentage had slightly decreased fire retardant performance of the coating.

  7. Solid particle erosion of plasma sprayed ceramic coatings

    Directory of Open Access Journals (Sweden)

    Branco José Roberto Tavares

    2004-01-01

    Full Text Available Thermal spraying allows the production of overlay protective coatings of a great variety of materials, almost without limitations as to its components, phases and constituents on a range of substrates. Wear and corrosion resistant coatings account for significant utilization of thermal spray processes. Besides being a means to evaluate the coating tribological performance, erosion testing allows also an assessment of the coating toughness and adhesion. Nevertheless, the relationship between the erosion behavior of thermal sprayed coatings and its microstructural features is not satisfactorily understood yet. This paper examines room temperature solid particle erosion of zirconia and alumina-based ceramic coatings, with different levels of porosity and varying microstrucutre and mechanical properties. The erosion tests were carried out by a stream of alumina particles with an average size of 50 µm at 70 m/s, carried by an air jet with impingement angle 90°. The results indicate that current erosion models based on hardness alone cannot account for experimental results, and, that there is a strong relationship between the erosion rate and the porosity.

  8. Ceramic Coatings for Clad (The C3 Project): Advanced Accident-Tolerant Ceramic Coatings for Zr-Alloy Cladding

    Energy Technology Data Exchange (ETDEWEB)

    Sickafus, Kurt E. [Univ. of Tennessee, Knoxville, TN (United States); Wirth, Brian [Univ. of Tennessee, Knoxville, TN (United States); Miller, Larry [Univ. of Tennessee, Knoxville, TN (United States); Weber, Bill [Univ. of Tennessee, Knoxville, TN (United States); Zhang, Yanwen [Univ. of Tennessee, Knoxville, TN (United States); Patel, Maulik [Univ. of Tennessee, Knoxville, TN (United States); Motta, Arthur [Pennsylvania State Univ., University Park, PA (United States); Wolfe, Doug [Pennsylvania State Univ., University Park, PA (United States); Fratoni, Max [Univ. of California, Berkeley, CA (United States); Raj, Rishi [Univ. of Colorado, Boulder, CO (United States); Plunkett, Kenneth [Univ. of Colorado, Boulder, CO (United States); Was, Gary [Univ. of Michigan, Ann Arbor, MI (United States); Hollis, Kendall [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nelson, Andy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Stanek, Chris [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Comstock, Robert [Westinghouse Electric Corporation, Pittsburgh, PA (United States); Partezana, Jonna [Westinghouse Electric Corporation, Pittsburgh, PA (United States); Whittle, Karl [Univ. of Sheffield (United Kingdom); Preuss, Michael [Univ. of Manchester (United Kingdom); Withers, Philip [Univ. of Manchester (United Kingdom); Wilkinson, Angus [Univ. of Oxford (United Kingdom); Donnelly, Stephen [Univ. of Huddersfield (United Kingdom); Riley, Daniel [Australian Nuclear Science and Technology Organisation, Syndney (Australia)

    2017-02-14

    The goal of this NEUP-IRP project is to develop a fuel concept based on an advanced ceramic coating for Zr-alloy cladding. The coated cladding must exhibit demonstrably improved performance compared to conventional Zr-alloy clad in the following respects: During normal service, the ceramic coating should decrease cladding oxidation and hydrogen pickup (the latter leads to hydriding and embrittlement). During a reactor transient (e.g., a loss of coolant accident), the ceramic coating must minimize or at least significantly delay oxidation of the Zr-alloy cladding, thus reducing the amount of hydrogen generated and the oxygen ingress into the cladding. The specific objectives of this project are as follows: To produce durable ceramic coatings on Zr-alloy clad using two possible routes: (i) MAX phase ceramic coatings or similar nitride or carbide coatings; and (ii) graded interface architecture (multilayer) ceramic coatings, using, for instance, an oxide such as yttria-stabilized zirconia (YSZ) as the outer protective layer. To characterize the structural and physical properties of the coated clad samples produced in 1. above, especially the corrosion properties under simulated normal and transient reactor operating conditions. To perform computational analyses to assess the effects of such coatings on fuel performance and reactor neutronics, and to perform fuel cycle analyses to assess the economic viability of modifying conventional Zr-alloy cladding with ceramic coatings. This project meets a number of the goals outlined in the NEUP-IRP call for proposals, including: Improve the fuel/cladding system through innovative designs (e.g. coatings/liners for zirconium-based cladding) Reduce or eliminate hydrogen generation Increase resistance to bulk steam oxidation Achievement of our goals and objectives, as defined above, will lead to safer light-water reactor (LWR) nuclear fuel assemblies, due to improved cladding properties and built-in accident resistance, as well as

  9. Structure and Properties Characterization of Ceramic Coatings Produced on Steel Using a Combined Technique

    Institute of Scientific and Technical Information of China (English)

    SHENDe-jiu; WANGYu-lin; GUWei-chao; XINGGuang-zhong

    2004-01-01

    Metallurgically bonded ceramic coatings were prepared on a steel surface with a combined method of arc spraying and micro-arc oxidation for the first time. Coatings were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Point and line distribution of elements of the ceramic coatings were determined using energy dispersive spectroscopy (EDS). Coatings abrasive wear resistance, corrosion resistance and hot impact property were assessed respectively. The property test results show that metallurgically bonded ceramic coatings were formed on aluminum coatings and the ceramic coatings is mainly composed of α-Al2O3, γ-Al2O3, θ-Al2O3 and a little amorphous. The coatings possess excellent abrasive wear, corrosion and hot shock resistance, which can in part be attributed to the gradual distribution of different phases from surface to the substrate.

  10. Materials characteristics of uncoated/ceramic-coated implant materials.

    Science.gov (United States)

    Lacefield, W R

    1999-06-01

    In this paper, the biocompatibility of dental implant materials is discussed in the context of both the mechanical characteristics of the materials and the type of surface presented to the surrounding tissues. The proper functioning of the implant depends on whether it possesses the strength necessary to withstand loading within the expected range, with other properties such as elongation being of importance in some instances. A suitable modulus of elasticity may be of major importance in situations when optimum load transmission from the implant into the surrounding bone is key to the successful functioning of the device. Dental implants present a wide range of surfaces to the surrounding tissues based on surface composition, texture, charge energy, and cleanliness (sterility). Metallic implants are characterized by protective oxide layers, but ion release is still common with these materials, and is a function of passivation state, composition, and corrosion potential. An effective surface treatment for titanium appears to be passivation or anodization in a suitable solution prior to implantation. Inert ceramic surfaces exhibit minimal ion release, but are similar to metals in that they do not form a high energy bond to the surrounding bone. Some of the newly developed dental implant alloys such as titanium alloys, which contain zirconium and niobium, and high-strength ceramics such as zirconia may offer some advantages (such as lower modulus of elasticity) over the conventional materials. Calcium phosphate ceramic coatings are commonly used to convert metallic surfaces into a more bioactive state and typically cause faster bone apposition. There is a wide range of ceramic coatings containing calcium and phosphorus, with the primary difference in many of these materials being in the rate of ion release. Although their long-term success rate is unknown, the calcium phosphate surfaces seem to have a higher potential for attachment of osteoinductive agents than do

  11. Environmental Barrier Coatings for Ceramic Matrix Composites - An Overview

    Science.gov (United States)

    Lee, Kang; van Roode, Mark; Kashyap, Tania; Zhu, Dongming; Wiesner, Valerie

    2017-01-01

    SiC/SiC Ceramic Matrix Composites (CMCs) are increasingly being considered as structural materials for advanced power generation equipment because of their light weight, higher temperature capability, and oxidation resistance. Limitations of SiC/SiC CMCs include surface recession and component cracking and associated chemical changes in the CMC. The solutions pursued to improve the life of SiC/SiC CMCs include the incorporation of coating systems that provide surface protection, which has become known as an Environmental Barrier Coating (EBC). The development of EBCs for the protection of gas turbine hot section CMC components was a continuation of coating development work for corrosion protection of silicon-based monolithics. Work on EBC development for SiC/SiC CMCs has been ongoing at several national laboratories and the original gas turbine equipment manufacturers. The work includes extensive laboratory, rig and engine testing, including testing of EBC coated SiC/SiC CMCs in actual field applications. Another EBC degradation issue which is especially critical for CMC components used in aircraft engines is the degradation from glassy deposits of calcium-magnesium-aluminosilicate (CMAS) with other minor oxides. This paper addresses the need for and properties of external coatings on SiC/SiC CMCs to extend their useful life in service and the retention of their properties.

  12. Ceramic Top Coats of Plasma-Sprayed Thermal Barrier Coatings: Materials, Processes, and Properties

    Science.gov (United States)

    Bakan, Emine; Vaßen, Robert

    2017-08-01

    The ceramic top coat has a major influence on the performance of the thermal barrier coating systems (TBCs). Yttria-partially-stabilized zirconia (YSZ) is the top coat material frequently used, and the major deposition processes of the YSZ top coat are atmospheric plasma spraying and electron beam physical vapor deposition. Recently, also new thermal spray processes such as suspension plasma spraying or plasma spray-physical vapor deposition have been intensively investigated for TBC top coat deposition. These new processes and particularly the different coating microstructures that can be deposited with them will be reviewed in this article. Furthermore, the properties and the intrinsic-extrinsic degradation mechanisms of the YSZ will be discussed. Following the TBC deposition processes and standard YSZ material, alternative ceramic materials such as perovskites and hexaaluminates will be summarized, while properties of pyrochlores with regard to their crystal structure will be discussed more in detail. The merits of the pyrochlores such as good CMAS resistance as well as their weaknesses, e.g., low fracture toughness, processability issues, will be outlined.

  13. Structural ceramic coatings in composite microtruss cellular materials

    Energy Technology Data Exchange (ETDEWEB)

    Bele, E.; Bouwhuis, B.A.; Codd, C. [Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, Ontario (Canada); Hibbard, G.D., E-mail: glenn.hibbard@utoronto.ca [Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, Ontario (Canada)

    2011-09-15

    Graphical abstract: The compressive strength increase per unit sleeve thickness of Al cores reinforced with Al{sub 2}O{sub 3} sleeves is lower than the corresponding strength increase when the same cores are reinforced with nanocrystalline Ni (n-Ni) sleeves (left). However, because anodizing is a transformative surface treatment, the Al{sub 2}O{sub 3} coating was able to achieve this performance increase with little overall weight penalty (right). Display Omitted Highlights: {yields} A new type of metal/ceramic microtruss cellular composite has been created. {yields} Reinforcing sleeves of Al{sub 2}O{sub 3} were deposited on low density Al microtruss cores. {yields} Significant compressive strength increases were seen at virtually no weight penalty. {yields} Failure mechanisms were studied by electron microscopy and finite element analysis. {yields} Buckling, sleeve wrinkling, and coating fracture dictated the compressive strength. - Abstract: In the present study, anodizing was used to produce Al{sub 2}O{sub 3} coatings in a conventional 3003 aluminum alloy microtruss core; a 38.5 {mu}m thick anodic coating provided a 143% increase in compressive strength. Finite-element analyses were used to illustrate the dependence of the compressive strength and failure mechanism on the thickness of the anodic coating. At low thicknesses the microtruss strength is dictated by global bucking of the internal struts. However, at higher thicknesses the compressive strength is controlled by coating fracture and local deformation in the hinge region of the struts. Regardless of the failure mechanism, the compressive strength of the composite microtruss increased with increasing anodic coating thickness, with very little corresponding weight penalty.

  14. Growth Kinetics of In Situ Fabricated Dense NbC Coatings on Gray Cast Iron

    Science.gov (United States)

    Shen, Liuliu; Xu, Yunhua; Zhao, Nana; Zhao, Ziyuan; Zhong, Lisheng; Song, Ke; Cai, Xiaolong; Wang, Juan

    2017-01-01

    In the present study, dense niobium carbide (NbC) coatings are fabricated by in situ techniques on gray cast iron (Fe) substrates at 1150 °C for 5 min, followed by a heat treatment at 990, 1010 and 1030 °C for 5, 10, 15 and 20 min. The microstructure, element composition and metallographic phase of the coating are characterized by scanning electron microscope, energy dispersive spectral and x-ray diffraction, respectively. Results show that the coating consists of NbC and α-Fe phases. NbC coating thickness ranges from 12.51 ± 1.4 to 29.17 ± 2.0 µm depending on the heat treatment temperature and time. In addition, the growth kinetics of dense niobium carbide coatings are estimated. A diffusion model based on Fick's laws is used to explore the carbon diffusion coefficients of the dense NbC coating in the range of heat treatment temperatures in which the experimental results of the kinetics of the niobium carbide coating are in good agreement with those estimated using diffusion model.

  15. Growth Kinetics of In Situ Fabricated Dense NbC Coatings on Gray Cast Iron

    Science.gov (United States)

    Shen, Liuliu; Xu, Yunhua; Zhao, Nana; Zhao, Ziyuan; Zhong, Lisheng; Song, Ke; Cai, Xiaolong; Wang, Juan

    2016-12-01

    In the present study, dense niobium carbide (NbC) coatings are fabricated by in situ techniques on gray cast iron (Fe) substrates at 1150 °C for 5 min, followed by a heat treatment at 990, 1010 and 1030 °C for 5, 10, 15 and 20 min. The microstructure, element composition and metallographic phase of the coating are characterized by scanning electron microscope, energy dispersive spectral and x-ray diffraction, respectively. Results show that the coating consists of NbC and α-Fe phases. NbC coating thickness ranges from 12.51 ± 1.4 to 29.17 ± 2.0 µm depending on the heat treatment temperature and time. In addition, the growth kinetics of dense niobium carbide coatings are estimated. A diffusion model based on Fick's laws is used to explore the carbon diffusion coefficients of the dense NbC coating in the range of heat treatment temperatures in which the experimental results of the kinetics of the niobium carbide coating are in good agreement with those estimated using diffusion model.

  16. Processing and optimization of functional ceramic coatings and inorganic nanomaterials

    Science.gov (United States)

    Nyutu, Edward Kennedy G.

    Processing of functional inorganic materials including zero (0-D) dimensional (e.g. nanoparticles), 1-D (nanorods, nanofibers), and 2-D (films/coating) structures is of fundamental and technological interest. This research will have two major sections. The first part of section one focuses on the deposition of silicon dioxide onto a pre-deposited molybdenum disilicide coating on molybdenum substrates for both high (>1000 °C) and moderate (500-600 °C) temperature oxidation protection. Chemical vapor deposition (CVD/MOCVD) techniques will be utilized to deposit the metal suicide and oxide coatings. The focus of this study will be to establish optimum deposition conditions and evaluate the metal oxide coating as oxidation - thermal barriers for Mo substrates under both isothermal (static) and cyclic oxidation conditions. The second part of this section will involve a systematic evaluation of a boron nitride (BN) interface coating prepared by chemical vapor deposition. Ceramic matrix composites (CMCs) are prospective candidates for high (>1000 °C) temperature applications and fiber- matrix interfaces are the dominant design parameters in ceramic matrix composites (CMCs). An important goal of the study is to determine a set of process parameters, which would define a boron nitride (BN) interface coating by a chemical vapor deposition (CVD) process with respect to coating. In the first part of the second section, we will investigate a new approach to synthesize ultrafine metal oxides that combines microwave heating and an in-situ ultrasonic mixing of two or more liquid precursors with a tubular flow reactor. Different metal oxides such as nickel ferrite and zinc aluminate spinels will be studied. The synthesis of metal oxides were investigated in order to study the effects of the nozzle and microwave (INM process) on the purity, composition, and particle size of the resulting powders. The second part of this research section involves a study of microwave frequency

  17. Film Coating Process Research and Characterization of TiN Coated Racetrack-type Ceramic Pipe

    CERN Document Server

    Wang, Jie; Zhang, Bo; Wei, Wei; Fan, Le; Pei, Xiangtao; Hong, Yuanzhi; Wang, Yong

    2015-01-01

    TiN film was coated on the internal face of racetrack-type ceramic pipe by three different methods: radio-frequency sputtering, DC sputtering and DC magnetron sputtering. The deposition rates of TiN film under different coating methods were compared. According to the AFM, SEM, XPS test results,these properties were analyzed, such as TiN film roughness and surface morphology. At the same time, the deposition rates were studied under two types' cathode, Ti wires and Ti plate. According to the SEM test results, Ti plate cathode can improve the TiN/Ti film deposition rate obviously.

  18. Thermo-mechanical Experiments of Y-PSZ Thermal Barrier Ceramic Coating with Bond Coat of Alumina

    Science.gov (United States)

    Sharma, Kamal Raj; Kumar, Gaurav

    2015-01-01

    In the present study, aluminum alloy (AlSi) substrates coated by Yttria stabilized zirconia used as thermal barrier have been investigated. The ceramic coating on the substrate is applied by plasma-spraying technique. Alumina (Al2O3) is used as a bond coat material. Four types of ceramic coating thickness (150, 250, 350 and 450 µm) were applied to AlSi materials which were cut out of diesel engine pistons with 100 µm thickness of bonding coat of Al2O3. The thermal torch and the thermal shock tests were conducted to coated samples which were made according to the international standards. Constant shock intensities were tested for 70 cycles on different thicknesses of the ceramic material and special attention was paid to the influence of thickness of the coating on the crazing phenomenon. Thermal resistance of thermal torch tested samples has been checked by drilling a hole in the middle of the samples and deformation time has been noted. Thermal shock tested samples were analyzed by X-ray diffraction machine and scanning electron microscopy machine. The diffractograms and micrographs have been obtained respectively for the samples. The diffractograms and micrographs of as sprayed samples and shock tested samples for different thickness have been compared, even the effect of thermal shock experiment on the different coating thickness of the ceramic have been analyzed. At the end of the tests, the most suitable ceramic coating thickness was determined.

  19. Ceramic fiber coatings development and demonstration. Final technical report, 1 July 1989-31 May 1993

    Energy Technology Data Exchange (ETDEWEB)

    Streckert, H.; Hazlebeck, D.; Montgomery, F.; Norton, K.; Schneir, I.

    1993-05-28

    The objective of this program was to develop fiber coating techniques by gas phase and liquid phase processes for interface control in ceramic matrix and metal matrix composites. Thermochemical evaluations of fiber/coating/matrix systems were performed theoretically and experimentally. Liquid phase processes were developed mainly for oxide coatings. Gas phase processes were developed for-carbide, nitride and boride coatings. Coatings were produced on continuous fiber tows and woven fabric. A small scale continuous fabric coater was designed and constructed. Coated fiber tows were infiltrated with silicon nitride matrix by chemical vapor deposition in order to study fiber matrix interactions. Composite coupons were made from Nicalon cloth and infiltrated with silicon nitride. Samples coated with high temperature BN showed flexural strengths up to 350 MPa.... Ceramic Fiber Coating, Chemical Vapor Deposition, Sol-Gel Ceramic Matrix Composites, Metal Matrix Composites.

  20. Structure and properties of ceramic coatings formed on aluminum alloys by microarc oxidation

    Institute of Scientific and Technical Information of China (English)

    LIU Wan-hui; BAO Ai-lian; LIU Rong-xiang; WU Wan-liang

    2006-01-01

    The thick and hard ceramic coatings were deposited on 2024 Al alloy by microarc oxidation in the electrolytic solution.Microstructure, phase composition and wear resistance of the oxide coatings were investigated by SEM, XRD and friction and wear tester. The microhardness and thickness of the oxide coatings were measured. The results show that the ceramic coating is mainly composed of α-Al2O3 and γ-Al2O3. During oxidation, the temperature in the microarc discharge channel is very high to make the local coating molten. From the surface to interior of the coating, microhardness increases gradually. The microhardness of the ceramic coating is HV1 800, and the microarc oxidation coatings greatly improve the antiwear properties of aluminum alloys.

  1. Precipitation Coating of Monazite on Woven Ceramic Fibers: 1. Feasibility (Postprint)

    Science.gov (United States)

    2007-02-01

    AFRL-ML-WP-TP-2006-480 PRECIPITATION COATING OF MONAZITE ON WOVEN CERAMIC FIBERS: I. FEASIBILITY (POSTPRINT) Geoff E. Fair, Randall S. Hay...GRANT NUMBER 4. TITLE AND SUBTITLE PRECIPITATION COATING OF MONAZITE ON WOVEN CERAMIC FIBERS: I. FEASIBILITY (POSTPRINT) 5c. PROGRAM ELEMENT...08 Aug 2006. Paper contains color. 14. ABSTRACT Monazite coatings were deposited on woven cloths and tows of NextelTM 610 fibers by heterogeneous

  2. Erosion resistance in metal - ceramic multilayer coatings for gas turbine compressor applications

    OpenAIRE

    1995-01-01

    The erosion resistance of 50 m metal-ceramic multilayer coatings has been investigated under impact conditions comparable to those in a gas turbine compressor cascade. lt was possible to improve upon the erosion resistance of Ti-6Al-4V by a significant margin. The influence of layer mechanical properties, layer thickness, ceramic content and coating process on erosion resistance has been studied over a range of impact conditions. The most suitable coating formula...

  3. Multilayer ceramic coating for impeding corrosion of sintered NdFeB magnets

    Institute of Scientific and Technical Information of China (English)

    A.Ali; A.Ahmad; K.M.Deen

    2009-01-01

    Sintered NdFeB magnets have complex microstructure that makes them susceptible to corrosion in active environments.The current paper evaluated the anticorrosion characteristics of multilayer titanium nitride ceramic coating applied through cathodic arc physical vapour deposition(CAPVD) for protection of sintered NdFeB permanent magnets.The performance of ceramic coating was compared to the electrodeposited nickel coating having a copper interlayer.Electrochemical impedance spectroscopy(EIS) and cyclic polar...

  4. Porous biomorphic silicon carbide ceramics coated with hydroxyapatite as prospective materials for bone implants.

    Science.gov (United States)

    Gryshkov, Oleksandr; Klyui, Nickolai I; Temchenko, Volodymyr P; Kyselov, Vitalii S; Chatterjee, Anamika; Belyaev, Alexander E; Lauterboeck, Lothar; Iarmolenko, Dmytro; Glasmacher, Birgit

    2016-11-01

    Porous and cytocompatible silicon carbide (SiC) ceramics derived from wood precursors and coated with bioactive hydroxyapatite (HA) and HA-zirconium dioxide (HA/ZrO2) composite are materials with promising application in engineering of bone implants due to their excellent mechanical and structural properties. Biomorphic SiC ceramics have been synthesized from wood (Hornbeam, Sapele, Tilia and Pear) using a forced impregnation method. The SiC ceramics have been coated with bioactive HA and HA/ZrO2 using effective gas detonation deposition approach (GDD). The surface morphology and cytotoxicity of SiC ceramics as well as phase composition and crystallinity of deposited coatings were analyzed. It has been shown that the porosity and pore size of SiC ceramics depend on initial wood source. The XRD and FTIR studies revealed the preservation of crystal structure and phase composition of in the HA coating, while addition of ZrO2 to the initial HA powder resulted in significant decomposition of the final HA/ZrO2 coating and formation of other calcium phosphate phases. In turn, NIH 3T3 cells cultured in medium exposed to coated and uncoated SiC ceramics showed high re-cultivation efficiency as well as metabolic activity. The recultivation efficiency of cells was the highest for HA-coated ceramics, whereas HA/ZrO2 coating improved the recultivation efficiency of cells as compared to uncoated SiC ceramics. The GDD method allowed generating homogeneous HA coatings with no change in calcium to phosphorus ratio. In summary, porous and cytocompatible bio-SiC ceramics with bioactive coatings show a great promise in construction of light, robust, inexpensive and patient-specific bone implants for clinical application.

  5. Improved ferroelectric, piezoelectric and electrostrictive properties of dense BaTiO{sub 3} ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Baraskar, Bharat G.; Kakade, S. G.; Kambale, R. C., E-mail: rckambale@gmail.com; Kolekar, Y. D., E-mail: ydk@physics.unipune.ac.in [Department of Physics, Savitribai Phule Pune University, Pune, Maharashtra, India 411 007 (India); James, A. R. [Defence Metallurgical Research Laboratory, Kanchanbagh P.O., Hyderabad, India - 500 058 (India)

    2016-05-23

    The ferroelectric, piezoelectric and electrostrictive properties of BaTiO{sub 3} (BT) dense ceramic synthesized by solid-state reaction were investigated. X-ray diffraction study confirmed tetragonal crystal structure having c/a ~1.0144. The dense microstructure was evidenced from morphological studies with an average grain size ~7.8 µm. Temperature dependent dielectric measurement showed the maximum values of dielectric constant, ε{sub r} = 5617 at Curie temperature, T{sub c} = 125 °C. The saturation and remnant polarization, P{sub sat.} = 24.13 µC/cm{sup 2} and P{sub r} =10.42 µC/cm{sup 2} achieved respectively for the first time with lower coercive field of E{sub c}=2.047 kV/cm. The polarization current density-electric field measurement exhibits the peaking characteristics, confirms the saturation state of polarization for BT. The strain-electric field measurements revealed the “sprout” shape nature instead of typical “butterfly loop”. This shows the excellent converse piezoelectric response with remnant strain ~ 0.212% and converse piezoelectric constant d*{sub 33} ~376.35 pm/V. The intrinsic electrostrictive coefficient was deduced from the variation of strain with polarization with electrostrictive coefficient Q{sub 33}~ 0.03493m{sup 4}/C{sup 2}.

  6. Structure and mechanical properties of ceramic coatings fabricated by plasma electrolytic oxidation on aluminized steel

    Science.gov (United States)

    Wu, Zhenqiang; Xia, Yuan; Li, Guang; Xu, Fangtao

    2007-08-01

    Ceramic coatings were formed by plasma electrolytic oxidation (PEO) on aluminized steel. Characteristics of the average anodic voltages versus treatment time were observed during the PEO process. The micrographs, compositions and mechanical properties of ceramic coatings were investigated. The results show that the anodic voltage profile for processing of aluminized steel is similar to that for processing bulk Al alloy during early PEO stages and that the thickness of ceramic coating increases approximately linearly with the Al layer consumption. Once the Al layer is completely transformed, the FeAl intermetallic layer begins to participate in the PEO process. At this point, the anodic voltage of aluminized steel descends, and the thickness of ceramic coating grows more slowly. At the same time, some micro-cracks are observed at the Al 2O 3/FeAl interface. The final ceramic coating mainly consists of γ-Al 2O 3, mullite, and α-Al 2O 3 phases. PEO ceramic coatings have excellent elastic recovery and high load supporting performance. Nanohardness of ceramic coating reaches about 19.6 GPa.

  7. Porous SiO{sub 2} nanofiber grafted novel bioactive glass–ceramic coating: A structural scaffold for uniform apatite precipitation and oriented cell proliferation on inert implant

    Energy Technology Data Exchange (ETDEWEB)

    Das, Indranee [Nano-Structured Materials Division, CSIR-Central Glass and Ceramic Research Institute, Kolkata 700032 (India); De, Goutam, E-mail: gde@cgcri.res.in [Nano-Structured Materials Division, CSIR-Central Glass and Ceramic Research Institute, Kolkata 700032 (India); Hupa, Leena [Johan Gadolin Process Chemistry Centre, Åbo Akademi University, FI-20500 Åbo (Finland); Vallittu, Pekka K. [Turku Clinical Biomaterials Centre—TCBC, University of Turku, FI-20520 Turku (Finland); Institute of Dentistry, University of Turku, Department of Biomaterials Science and City of Turku, Welfare Division, Turku (Finland)

    2016-05-01

    A composite bioactive glass–ceramic coating grafted with porous silica nanofibers was fabricated on inert glass to provide a structural scaffold favoring uniform apatite precipitation and oriented cell proliferation. The coating surfaces were investigated thoroughly before and after immersion in simulated body fluid. In addition, the proliferation behavior of fibroblast cells on the surface was observed for several culture times. The nanofibrous exterior of this composite bioactive coating facilitated homogeneous growth of flake-like carbonated hydroxyapatite layer within a short period of immersion. Moreover, the embedded porous silica nanofibers enhanced hydrophilicity which is required for proper cell adhesion on the surface. The cells proliferated well following a particular orientation on the entire coating by the assistance of nanofibrous scaffold-like structural matrix. This newly engineered composite coating was effective in creating a biological structural matrix favorable for homogeneous precipitation of calcium phosphate, and organized cell growth on the inert glass surface. - Highlights: • Fabricated porous SiO{sub 2} nanofibers grafted composite bioactive glass–ceramic coating on inert glass. • The newly engineered coating facilitates uniformly dense apatite precipitation. • Embedded porous silica nanofibers enhance hydrophilicity of the coated surface. • Cells proliferate well on the entire coating following a particular orientation by the assistance of nanofibers. • The coatings have potential to be used as biological scaffold on the surface of implants.

  8. Structure-property relationship of ceramic coatings on metals produced by laser processing

    NARCIS (Netherlands)

    de Hosson, J.T.M.; van den Burg, M.; Mazumder, J; Conde, O; Villar, R; Steen, W

    1996-01-01

    This paper concentrates on the mechanical performance of various ceramic coatings of Cr2O3 on steel (SAF2205), as produced by CO2 laser processing. The thickness of the coating that can be applied by laser coating is limited to about 200 mu m setting a limit to the maximum strain energy release rate

  9. Laboratory evaluation of ceramic coatings for diesel exhaust valves. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Scharnweber, D H; Vukovich, D T

    1980-11-01

    Diesel engine exhaust valves coated with zirconia and calcium silicate ceramic coating systems, developed by the Central Institute for Industrial Research, Oslo, Norway, were laboratory fixture tested to assess bond strength and structural integrity under representative mechanical and thermal stress conditions. The results indicate the zirconia coating systems are worthy of additional evaluation in a medium or high speed industrial/utility diesel engine.

  10. Effect of oxidation time on the microstructure and properties of ceramic coatings prepared by microarc oxidation on 7A04 superhard aluminum alloy

    Science.gov (United States)

    Xiao, Feng; Chen, Hui; Miao, Jingguo; Du, Juan

    2017-07-01

    Under the sodium aluminates’ system, microarc oxidation treatment was conducted on the superhard aluminum alloy 7A04 for different times. The microstructure of microarc oxidation ceramic layer was investigated by using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The influences of different oxidation times on the adhesion strength of ceramic layer and substrate, the morphology of surface and cross-section, the phase composition and the electrochemical properties were studied. The results indicated that the connection of the coating and substrate appears to be metallurgical bonding and dense ceramic layer, and the surface is in a “volcanic vent” morphology, which is composed of γ-Al2O3 and little α-Al2O3. The corrosion resistance of ceramic layer is improved significantly in contrast with that of the substrate.

  11. Wear resistance of ceramic coating on AZ91 magnesium alloy by micro-arc oxidation

    Institute of Scientific and Technical Information of China (English)

    ZHAO Hui; LIU Zheng; CHEN Li-jia; CHEN Ji; HAN Zhong

    2006-01-01

    The ceramic coating formed on AZ91 magnesium alloy by micro-arc oxidation (MAO) was characterized. The results show that the ceramic coating(3.4-23 μm in thickness)on the surface of AZ91 alloy was attained under different micro-arc oxidation treatment conditions, which consist mainly of MgO, Mg2SiO4 and MgSiO3 phases. Nano-hardness in a cross-sectional specimen was determined by nano-indentation experiment. The MAO coatings exhibit higher hardness than the substrate. Dry sliding wear tests for the MAO coatings and AZ91 alloy were also carried out using an oscillating friction and wear tester in a ball-on-disc contact configuration. The wear resistance of the MAO coatings is improved respectively under different treatment time as a result of different structures of ceramic coatings formed on AZ91 alloy.

  12. Element Analysis of Ceramic Coatings under Spherical Indentation with Metallic Interlayer:Part Ⅱ Ring Crack

    Institute of Scientific and Technical Information of China (English)

    Minh-Quy LE; Seock-Sam KIM

    2006-01-01

    Spherical indentation of ceramic coatings with metallic interlayer was performed by means of axisymmetric finite element analysis(FEA). Two typical ceramic coatings with relatively high and low elastic modulus deposited on aluminum alloy and carbon steel were considered. The fracture mechanics of the ceramic coatings mechanisms due to occurrence of surface ring cracks extending traverse the coating thickness under spherical indentation are investigated within the framework of linear fracture mechanics. The J-integral associated to such cracks was computed. The evolution of J-integral vs the crack length and the indentation depth was studied. The effects of the interlayer, the coating and the substrate on the J-integral evolution were discussed. The results show that a suitable metallic interlayer can improve the fracture resistance of the coating systems under the same indentation conditions through reducing the J-integral.

  13. Mechanisms governing the interfacial delamination of thermal barrier coating system with double ceramic layers

    Science.gov (United States)

    Xu, Rong; Fan, Xueling; Wang, T. J.

    2016-05-01

    A systematic study of factors affecting the interfacial delamination of thermal barrier coating system (TBCs) with double ceramic layers (DCL) is presented. Crack driving forces for delaminations at two weak interfaces are examined. The results show that a thicker outermost ceramic layer can induce dramatic increase in crack driving force and make the interface between two ceramic coatings become more prone to delamination. The behavior is shown to be more prominent in TBCs with stiffer outmost coating. The thickness ratio of two ceramic layers is an important parameter for controlling the failure mechanisms and determining the lifetime of DCL TBCs under inservice condition. By accounting for the influences of thickness ratio of two ceramic layers and interfacial fracture toughnesses of two involved interfaces, the fracture mechanism map of DCL TBCs has been constructed, in which different failure mechanisms are identified. The results quanlitatively agree with the aviliable experimental data.

  14. Hydrogen Permeation Properties of Perovskite-type BaCe0.9Mn0.1O3-δDense Ceramic Membrane

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The electrical conduction properties of dense BaCe0.9Mn0.1O3-δ (BCM10) membrane were investigated in the temperature range of 600-900℃. High ionic and electronic conductivities at elevated temperatures make BCM10 a potential ceramic material for hydrogen separation. Hydrogen permeation through BCM10 membranes was studied using a hightemperature permeation cell. Little hydrogen could be detected at the sweep side. However,appreciable hydrogen can permeate through BCM10 membrane coated with porous platinum black,which shows that the process of hydrogen permeation through BCM10 membranes was controlled by the catalytic decomposition and recomposition of hydrogen on the surfaces of BCM10 membranes.

  15. Low-Cost Innovative Hi-Temp Fiber Coating Process for Advanced Ceramic Matrix Composites Project

    Data.gov (United States)

    National Aeronautics and Space Administration — MATECH GSM (MG) proposes 1) to demonstrate a low-cost innovative Hi-Temp Si-doped in-situ BN fiber coating process for advanced ceramic matrix composites in order to...

  16. Thermal shock behavior of toughened gadolinium zirconate/YSZ double-ceramic-layered thermal barrier coating

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Xinghua, E-mail: xhzhong@mail.sic.ac.cn; Zhao, Huayu; Zhou, Xiaming; Liu, Chenguang; Wang, Liang; Shao, Fang; Yang, Kai; Tao, Shunyan; Ding, Chuanxian

    2014-04-01

    Highlights: • Gd{sub 2}Zr{sub 2}O{sub 7}/YSZ DCL thermal barrier coating was designed and fabricated. • The Gd{sub 2}Zr{sub 2}O{sub 7} top ceramic layer was toughened by addition of nanostructured 3YSZ. • Remarkable improvement in thermal shock resistance of the DCL coating was achieved. - Abstract: Double-ceramic-layered (DCL) thermal barrier coating system comprising of toughened Gadolinium zirconate (Gd{sub 2}Zr{sub 2}O{sub 7}, GZ) as the top ceramic layer and 4.5 mol% Y{sub 2}O{sub 3} partially-stabilized ZrO{sub 2} (4.5YSZ) as the bottom ceramic layer was fabricated by plasma spraying and thermal shock behavior of the DCL coating was investigated. The GZ top ceramic layer was toughened by addition of nanostructured 3 mol% Y{sub 2}O{sub 3} partially-stabilized ZrO{sub 2} (3YSZ) to improve fracture toughness of the matrix. The thermal shock resistance of the DCL coating was enhanced significantly compared to that of single-ceramic-layered (SCL) GZ-3YSZ composite coating, which is believed to be primarily attributed to the two factors: (i) the increase in fracture toughness of the top ceramic layer by incorporating nanostructured YSZ particles and (ii) the improvement in strain tolerance through the utilization of 4.5YSZ as the bottom ceramic layer. In addition, the failure mechanisms are mainly attributed to the still low fracture toughness of the top ceramic layer and oxidation of the bond-coat.

  17. Improvement on Performances of Internal Combustion Engine Using the Technology of Ceramic Coating

    Institute of Scientific and Technical Information of China (English)

    林建生; 付晓光; 张建昭

    2003-01-01

    This paper introduces a new technology of using ceramic coating on piston rings of an internal combustion engine, and the comparison of mechanical efficiency and performances of an actual engine before and after the application of ceramic coating on the piston rings. The experimental results show that the mechanical efficiency and power output are enhanced by 4% and 2.6%, respectively, with fuel consumption reduced by 2.9%. Further studies on coating processing and coating materials as well as the reliability and durability will be of great significance in the application and popularization of the new technology.

  18. Implantable devices having ceramic coating applied via an atomic layer deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Xinhua; Weimer, Alan W.; Bryant, Stephanie J.

    2016-03-08

    Substrates coated with films of a ceramic material such as aluminum oxides and titanium oxides are biocompatible, and can be used in a variety of applications in which they are implanted in a living body. The substrate is preferably a porous polymer, and may be biodegradable. An important application for the ceramic-coated substrates is as a tissue engineering scaffold for forming artificial tissue.

  19. Experimental study of ceramic-coated tip seals for turbojet engines

    Science.gov (United States)

    Biesiadny, T. J.; Mcdonald, G.; Hendricks, R. C.; Klann, G. A.; Lassow, E. S.

    1985-01-01

    Ceramic gas-path seals were fabricated and successfully operated over 1000 cycles from flight idle to maximum power in a small turboshaft engine. The seals were fabricated by plasma spraying zirconia over a NiCoCrAlX bond coat on the Haynes 25 substrate. Coolant-side substrate temperatures and related engine parameters were recorded. Post-test inspection revealed mudflat surface cracking with penetration to the ceramic bond-coat interface.

  20. Sol-gel coatings as active barriers to protect ceramic reinforcement in aluminum matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Rams, J.; Urena, A.; Campo, M. [Departamento de Tecnologia Quimica, Ambiental y de los Materiales, ESCET, Universidad Rey Juan Carlos C/ Tulipan s/nMostoles 28933 Madrid (Spain)

    2004-02-01

    Silica obtained through a sol-gel process is used as a coating for ceramic reinforcements (SiC) in aluminium matrix composite materials. The interaction between molten aluminium and the coated particles during material casting can be controlled by means of the thermal treatment given to the coating. Wettability is increased because the coating reacts with molten aluminium, and the formation of the degrading aluminium carbide is inhibited. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

  1. Microstructure and Scratch Resistance of TaC Dense Ceramic Layer on an Iron Matrix

    Science.gov (United States)

    Zhao, Nana; Xu, Yunhua; Zhong, Lisheng; Yan, Honghua; Ovcharenko, Vladimir E.

    2016-06-01

    A tantalum carbide dense ceramic layer with a thickness of ~20 μm was produced on the surface of an iron matrix using an in situ technique. The morphology, microstructure, and phase composition of the layer were characterized by means of SEM, TEM, and XRD. The results show fairly agglomerated and uniformly sized (~200 nm) TaC particulates with a face-cantered cubic structure. The values of nano-hardness for the surface and cross section of reinforcing layer can be as high as 29.5 ± 0.6 and 26.7 ± 0.1 GPa, respectively, which were analyzed using a nano-indentation apparatus. Moreover, the scratch resistance of the layer was measured by scratch tests under a progressively increasing load of 0-100 N. A high critical load of 90.4 N is obtained. It is worthy to note that there are only cracking, slight splitting, and small flaking pits (even at the maximum load) all over the whole scratch process, namely the reinforcing layer can protect the iron matrix from serious abrasion effectively. In addition, the excellent scratch resistance and mechanism are discussed in detail.

  2. Glass and glass–ceramic coatings, versatile materials for industrial and engineering applications

    Indian Academy of Sciences (India)

    Amitava Majumdar; Sunirmal Jana

    2001-02-01

    Among various coating systems for industrial and engineering applications, glass and glass–ceramic coatings have advantages of chemical inertness, high temperature stability and superior mechanical properties such as abrasion, impact etc as compared to other coating materials applied by thermal spraying in its different forms viz. PVD, CVD, plasma, etc. Besides imparting required functional properties such as heat, abrasion and corrosion resistance to suit particular end use requirements, the glass and glass–ceramic coatings in general also provide good adherence, defect free surface and refractoriness. Systematic studies covering the basic science of glass and glass–ceramic coatings, the functional properties required for a particular end-use along with the various fields of application have been reviewed in this paper.

  3. Ceramic-coated components for the combustion zone of natural gas engines

    Science.gov (United States)

    Holloman, L.; Levy, A. V.

    1992-03-01

    The use of ceramic coatings on the combustion zone surfaces of large,natural gas-fueled,internal com-bustion engines is discussed. Unique handling and quality control systems are required for plasma spray-ing thin (0.25 mm,0.0010) in.coatings on up to 48.25(cm19)-in.diameter piston crowns and cylinder heads weighing up to(1200 lb).The in-service performance characteristics of two types of natural gas-fu-eled combustion engines powering natural gas compressors that had thin zirconia ceramic coatings ap-plied to their combustion zone surfaces are presented. Their performance was measured in the field be-fore and after coating. It was determined that the durability,power output,fuel consumption,exhaust emissions,and other operating characteristics all improved due to ceramic coating of the flame side sur-faces of cylinder heads,power pistons,and valves.

  4. Dense and porous titanium substrates with a biomimetic calcium phosphate coating

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, A.A., E-mail: aantunesr@yahoo.com.br [Powder Technology Laboratory, Materials Processing and Characterization Division, National Institute of Technology, No. 82 Venezuela Avenue, Room 602, 20081-312 Rio de Janeiro, RJ (Brazil); Balestra, R.M. [Powder Technology Laboratory, Materials Processing and Characterization Division, National Institute of Technology, No. 82 Venezuela Avenue, Room 602, 20081-312 Rio de Janeiro, RJ (Brazil); Rocha, M.N. [Metallurgical and Materials Engineering Program, COPPE, Federal University of Rio de Janeiro, P.O. Box 68505, 21941-972 Rio de Janeiro, RJ (Brazil); Peripolli, S.B. [Materials Metrology Division, National Institute of Metrology, Normalization and Quality, No. 50 Nossa Senhora das Gracas Street, Building 3, 25250-020 Duque de Caxias, RJ (Brazil); Andrade, M.C. [Polytechnic Institute of Rio de Janeiro, Rio de Janeiro State University, s/n, Alberto Rangel Street, 28630-050 Nova Friburgo, RJ (Brazil); Pereira, L.C. [Metallurgical and Materials Engineering Program, COPPE, Federal University of Rio de Janeiro, P.O. Box 68505, 21941-972 Rio de Janeiro, RJ (Brazil); Oliveira, M.V. [Powder Technology Laboratory, Materials Processing and Characterization Division, National Institute of Technology, No. 82 Venezuela Avenue, Room 602, 20081-312 Rio de Janeiro, RJ (Brazil)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer A biomimetic coating method with simplified solution is proposed. Black-Right-Pointing-Pointer Titanium substrates are submitted to chemical and heat treatments. Black-Right-Pointing-Pointer Titanium substrates are coated with biocompatible calcium phosphate phases. Black-Right-Pointing-Pointer The simplified solution shows potential to be applied as a coating technique. - Abstract: The present work studied a biomimetic method using a simplified solution (SS) with calcium and phosphorus ions for coating titanium substrates, in order to improve their bioactivity. Commercially pure titanium dense sheet, microporous and macroporous titanium samples, both produced by powder metallurgy, were treated in NaOH solution followed by heat-treating and immersed in SS for 7, 14 or 21 days. The samples characterization was performed by quantitative metallographic analysis, confocal scanning optical microscopy, scanning electron microscopy, energy dispersive spectroscopy and low angle X-ray diffraction. The results showed coatings with calcium phosphate precipitation in all samples, with globular or plate-like morphology, typical of hydroxyapatite and octacalcium phosphate, respectively, indicating that the solution (SS) has potential for coating titanium substrates. In addition, the different surfaces of substrates had an effect on the formed calcium phosphate phase and thickness of coatings, depending on the substrate type and imersion time in the simplified solution.

  5. Preparation and characterization of dense graphite/glassy carbon composite coating for sealing application

    Science.gov (United States)

    Wang, Yang; Chen, Zhaofeng; Yu, Shengjie; Pan, Ning; Liao, Jiahao

    2017-09-01

    Glassy carbon (GC), characterized by a homogeneous structure and glass-like fracture surface once broken, has attracted increasing attention because of its excellent performance. In this paper, a dense graphite/glassy carbon composite coating with low gas permeability was introduced. In this composite coating, small graphite particles acting as second phase were wrapped by glassy carbon matrix. The composite coatings with different mass fractions of graphite particles were prepared. The mass loss of phenolic resin was determined by TG (thermogravimetry) analysis to determine the pyrolysis process. Raman spectrum analysis indicates that graphite content in composite coatings affected the G/D ratio significantly. The permeability of composite coatings with 50% and 100% graphite particles was almost same, which was ranged from 6  ×  10‑13 m3 · µm/m2 · s · Pa to 3  ×  10‑13 m3 · µm/m2 · s · Pa within the differential pressure from 100 kPa to 70 kPa. While the composite coating with 150% graphite particles had higher gas permeability due to the tiny micro-cracks and micro-pores produced. What was more, the densification mechanism of graphite/glassy carbon composite coating was also discussed in detail.

  6. The Influence of Surface Morphology of Dense Ca-P Ceramics on Apatite Formation in Dynamic SBF

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    This study aimed at exploring the effect of surface morphology of dense phosphate calcium (Ca-P) ceramics upon the formation of bone-like apatite in static or dynamic simulated body fluid (SBF). Dense and sandblasted calcium phosphate ceramics were immersed into dynamic SBF flowing at normal physiological speed of body fluid of skeletal muscle.The changes were characterized using SEM, XPS, IR and XRD. Changes can be observed after the sandblasted surface of dense calcium phosphate ceramics had been immersed in SBF for 14 days. XPS analysis results showed that the flake-like structure was composed of Ca, P, C, O; IR analysis result of surface structure of samples showed that there were specific peaks for CO2-3; XRD results indicated the decrease in crystallinity and the increase in amorphous structure. The rough surface was advantageous for the formation of bone-like apatite. Increasing the Ca2+, HPO2-4 concentration of SBF could also enhance the bone like apatite formation. All the results demonstrated that local concentration is a key factor affecting nucleation.

  7. Characteristics of Plasma-Sprayed Ceramic Coatings and Their Engineering Application

    Institute of Scientific and Technical Information of China (English)

    DENG Hua-ling; ZHANG Zhong-wen; WU Jun

    2004-01-01

    The microstructure, porosity, microhardness and adhesive strength of three plasma- sprayed ceramic coatings (Al2 O3, Cr2 O3 and Cr3 C2 + NiCr) were tested. The wear resistance of the coatings was characterized through sand blasting test. The results showed that the erosion resistance of Cr2 O3 coating was better than Al2 O3 and Cr3 C2 + NiCr coatings'.Through depositing the coating on the surface of boiler overheater tubes and on the surface of baffle- wall of carrying- coal grain blower to test its anti- erosion performance after a period of running, it was confirmed that the coatings present excellent wear resistance. Accordingly, it also demonstrates that ceramic coating has a promising prospects in surface protection in thermal power stations.

  8. Stability of aqueous nano-ceramic coatings with two different dispersants

    Institute of Scientific and Technical Information of China (English)

    夏长清; 古一; 曾凡浩

    2003-01-01

    The effects of sodium carboxymethyl cellulose and sodium citrate as dispersants on nano-ceramic aqueous suspension were examined by the measurements of ζ-potential and the sedimentation test. The results show that proper addition of sodium carboxymethyl cellulose or sodium citrate into nano-ceramic coating, exhibits an enhanced dispersion and stability compared with the coating without dispersants. The negative ζ-potential of the particles in the nano-coating increases with the increase of pH value of the coating, and the curve of ζ-pH moves to lower pH range when the dispersants are added into the coating. To ensure that the coating has not only good stability and dispersibility but also no corrosivity to substrate alloy, adding 1.00% sodium citrate into coating with pH value of 7-8 is preferable to adding sodium carboxymethyl cellulose.

  9. Apatite formation on alkaline-treated dense TiO2 coatings deposited using the solution precursor plasma spray process.

    Science.gov (United States)

    Chen, Dianying; Jordan, Eric H; Gell, Maurice; Wei, Mei

    2008-05-01

    A dense titania (TiO2) coating was deposited from an ethanol-based solution containing titanium isopropoxide using the solution precursor plasma spray (SPPS) process. XRD and Raman spectrum analyses confirmed that the coating is exclusively composed of rutile TiO2. SEM micrographs show the as-sprayed coating is dense with a uniform thickness and there are no coarse splat boundaries. The as-sprayed coating was chemically treated in 5M NaOH solution at 80 degrees C for 48 h. The bioactivity of as-sprayed and alkaline-treated coatings was investigated by immersing the coatings in simulated body fluid (SBF) for 14-28 days, respectively. After 28 days immersion, there is a complete layer of carbonate-containing apatite formed on the alkaline-treated TiO2 coating surface, but none formed on the as-sprayed coating.

  10. Deformation Behavior of Nanostructured Ceramic Coatings Deposited by Thermal Plasma Spray

    Institute of Scientific and Technical Information of China (English)

    Xianliang JIANG; Eric Jordan; Leon Shaw; Maurice Gell

    2004-01-01

    Al2O3-13 wt pct TiO2 coating deposited by direct current plasma spray consists of nanostructured region and microlamellae. Bend test shows that the ceramic coating can sustain some deformation without sudden failure. The deformation is achieved through the movement of nano-particles in the nanostructured region under tensile stress.

  11. STUDY OF PARTICLE COATINGS FOR THE DESIGN OF INTERGRANULAR PHASES IN ENGINEERING CERAMICS

    NARCIS (Netherlands)

    DJURICIC, B; DAVIES, IJ; PICKERING, S; MCGARRY, D; BULLOCK, E

    1995-01-01

    The deposition of nano-dimension coatings of Y2O3 and/or Y2O3/Al2O3 precursor material onto Si3N4 and SiC particles provides a methodology far the uniform dispersion of sintering aid and the compositional tailoring of intergranular phases in engineering ceramics. Coatings were precipitated from aque

  12. Tribological investigation of metal-ceramic composite coatings in high temperature

    Institute of Scientific and Technical Information of China (English)

    H.T.MA; R.J.ZHANG; Y.S.JIN; G.Barbezat

    2001-01-01

    The high temperature tribological properties of metal-based ceramic coating containingoxidation under dry wear condition were studied in this paper. It shows that the coating exhibitedself-lubricated properties only in the high temperature range, and the abrasion, adhesion and oxi-dation are the main wear modes.

  13. Research on chemical vapor deposition processes for advanced ceramic coatings

    Science.gov (United States)

    Rosner, Daniel E.

    1993-01-01

    Our interdisciplinary background and fundamentally-oriented studies of the laws governing multi-component chemical vapor deposition (VD), particle deposition (PD), and their interactions, put the Yale University HTCRE Laboratory in a unique position to significantly advance the 'state-of-the-art' of chemical vapor deposition (CVD) R&D. With NASA-Lewis RC financial support, we initiated a program in March of 1988 that has led to the advances described in this report (Section 2) in predicting chemical vapor transport in high temperature systems relevant to the fabrication of refractory ceramic coatings for turbine engine components. This Final Report covers our principal results and activities for the total NASA grant of $190,000. over the 4.67 year period: 1 March 1988-1 November 1992. Since our methods and the technical details are contained in the publications listed (9 Abstracts are given as Appendices) our emphasis here is on broad conclusions/implications and administrative data, including personnel, talks, interactions with industry, and some known applications of our work.

  14. Application of Ceramic Coat Synthesized by In-Situ Combustion Synthesis to BF Tuyere

    Institute of Scientific and Technical Information of China (English)

    YANG Da-zheng; GUAN Yong; ZHANG Yue; LI Jing; HU Jun-ge; LI Wen-zhu

    2007-01-01

    A novel technology of tuyere protection is introduced. The ceramic coat is synthesized by using in-situ combustion process as the internal, external, and nose protecting coat of BF tuyeres. It can effectively protect the tuyeres and reduce heat loss by cooling water. The technology is quick-acting, easy to use, energy-saving and can make tuyeres have long service life. The feasibility of the application of the tuyere ceramic coat is discussed and the energy-saving effect of the tuyere is compared with that of the tuyeres lined with refractory.

  15. Dense and high-stability Ti2AlN MAX phase coatings prepared by the combined cathodic arc/sputter technique

    Science.gov (United States)

    Wang, Zhenyu; Liu, Jingzhou; Wang, Li; Li, Xiaowei; Ke, Peiling; Wang, Aiying

    2017-02-01

    Ti2AlN belongs to a family of ternary nano-laminate alloys known as the MAX phases, which exhibit a unique combination of metallic and ceramic properties. In the present work, the dense and high-stability Ti2AlN coating has been successfully prepared through the combined cathodic arc/sputter deposition, followed by heat post-treatment. It was found that the as-deposited Ti-Al-N coating behaved a multilayer structure, where (Ti, N)-rich layer and Al-rich layer grew alternately, with a mixed phase constitution of TiN and TiAlx. After annealing at 800 °C under vacuum condition for 1.5 h, although the multilayer structure still was found, part of multilayer interfaces became indistinct and disappeared. In particular, the thickness of the Al-rich layer decreased in contrast to that of as-deposited coating due to the inner diffusion of the Al element. Moreover, the Ti2AlN MAX phase emerged as the major phase in the annealed coatings and its formation mechanism was also discussed in this study. The vacuum thermal analysis indicated that the formed Ti2AlN MAX phase exhibited a high-stability, which was mainly benefited from the large thickness and the dense structure. This advanced technique based on the combined cathodic arc/sputter method could be extended to deposit other MAX phase coatings with tailored high performance like good thermal stability, high corrosion and oxidation resistance etc. for the next protective coating materials.

  16. Preparation technology and anti-corrosion performances of black ceramic coatings formed by micro-arc oxidation on aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    CHEN Ling; HAN Jing; YU Shengxue

    2006-01-01

    In order to prepare ornamental and anti-corrosive coating on aluminum alloys, preparation technology of black micro-arc ceramic coatings on Al alloys in silicate based electrolyte was studied.The influence of content of Na2WO4 and combination additive in solution on the performance of black ceramic coatings was studied; the anticorrosion performances of black ceramic coatings were evaluated through whole-immersion test and electrochemical method in 3.5% NaCl solution at different pH value; SEM and XRD were used to analyze the surface morphology and phase constitutes of the black ceramic coatings.Experimental results indicated that, without combination additives, with the increasing of Na2WO4 content in the electrolyte, ceramic coating became darker and thicker, but the color was not black; after adding combination additive, the coating turned to be black; the black ceramic coating was multi-hole form in surface.There was a small quantity of tungsten existing in the black ceramic coating beside α-Al2O3 phase and β-Al2O3 phase.And aluminum alloy with black ceramic coating exhibited excellent anti-corrosion property in acid, basic and neutral 3.5% NaCl solution.

  17. Nanostructured bioactive glass-ceramic coatings deposited by the liquid precursor plasma spraying process

    Science.gov (United States)

    Xiao, Yanfeng; Song, Lei; Liu, Xiaoguang; Huang, Yi; Huang, Tao; Wu, Yao; Chen, Jiyong; Wu, Fang

    2011-01-01

    Bioactive glass-ceramic coatings have great potential in dental and orthopedic medical implant applications, due to its excellent bioactivity, biocompatibility and osteoinductivity. However, most of the coating preparation techniques either produce only thin thickness coatings or require tedious preparation steps. In this study, a new attempt was made to deposit bioactive glass-ceramic coatings on titanium substrates by the liquid precursor plasma spraying (LPPS) process. Tetraethyl orthosilicate, triethyl phosphate, calcium nitrate and sodium nitrate solutions were mixed together to form a suspension after hydrolysis, and the liquid suspension was used as the feedstock for plasma spraying of P 2O 5-Na 2O-CaO-SiO 2 bioactive glass-ceramic coatings. The in vitro bioactivities of the as-deposited coatings were evaluated by soaking the samples in simulated body fluid (SBF) for 4 h, 1, 2, 4, 7, 14, and 21 days, respectively. The as-deposited coating and its microstructure evolution behavior under SBF soaking were systematically analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), inductively coupled plasma (ICP), and Fourier transform infrared (FTIR) spectroscopy. The results showed that P 2O 5-Na 2O-CaO-SiO 2 bioactive glass-ceramic coatings with nanostructure had been successfully synthesized by the LPPS technique and the synthesized coatings showed quick formation of a nanostructured HCA layer after being soaked in SBF. Overall, our results indicate that the LPPS process is an effective and simple method to synthesize nanostructured bioactive glass-ceramic coatings with good in vitro bioactivity.

  18. Application of Ceramic Bond Coating for Reusable Melting Crucible of Metallic Fuel Slugs

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki-Hwan; Song, Hoon; Ko, Young-Mo; Park, Jeong-Yong; Lee, Chan-Bock [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Hong, Ki-Won [Chungnam National University, Daejeon (Korea, Republic of)

    2016-10-15

    Metal fuel slugs of the driver fuel assembly have been fabricated by injection casting of the fuel alloys under a vacuum state or an inert atmosphere. Traditionally, metal fuel such as a U-Zr alloy system for SFR has been melted in slurry-coated graphite crucibles and cast in slurry-coated quartz tube molds to prevent melt/material interactions. Reactive coatings and porous coatings can be a source of melt contaminations, and fuel losses, respectively. Ceramic Y{sub 2}O{sub 3}, TiC, and TaC coating materials showed no penetration in the protective layer after a melt dipping test. However, the ceramic coating materials showed separations in the coating interface between the substrate and coating layer, or between the coating layer and fuel melt after the dipping test. All plasma-spray coated methods maintained a sound coating state after a dipping test with U-10wt.%Zr melt. A single coating Y{sub 2}O{sub 3}(150) layer and double coating layer of TaC(50)-Y{sub 2}O{sub 3}(100), showed a sound state or little penetration in the protective layer after a dipping test with U-10wt.%Zr-5wt.%RE melt. Injection casting experiments of U-10wt.%Zr and U-10wt.%Zr-5wt.%RE fuel slugs have been performed to investigate the feasibility of a reusable crucible of the metal fuel slugs. U–10wt.%Zr and U–10wt.%Zr–5wt.%RE fuel slugs have been soundly fabricated without significant interactions of the graphite crucibles. Thus, the ceramic plasma-spray coatings are thought to be promising candidate coating methods for a reusable graphite crucible to fabricate metal fuel slugs.

  19. Corrosion protection of SiC-based ceramics with CVD mullite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Auger, M.L.; Sarin, V.K. [Boston Univ., MA (United States). Dept. of Mfg. Engineering

    1997-12-01

    For the first time, crystalline mullite coatings have been chemically vapor deposited on SiC substrates to enhance its corrosion and oxidation resistance. Thermodynamic and kinetic considerations have been utilized to produce mullite coatings with a variety of growth rates, compositions, and morphologies. The flexibility of processing can be exploited to produce coated ceramics with properties tailored to specific applications and varied corrosive environments.

  20. Nondestructive evaluation of the interface between ceramic coating and stainless steel by electromagnetic method

    Science.gov (United States)

    Savin, A.; Steigmann, R.; Iftimie, N.; Novy, F.; Vizureanu, P.; Craus, M. L.; Fintova, S.

    2016-08-01

    Protecting coatings as thermal barrier coating (TBC) are used for yield improvement of equipment working at high temperature. Zirconia doped with yttria ceramics are considered a good TBC material due of its low thermal conductivity, refractory, chemical inertness and compatible thermal expansion coefficient with metallic support. The paper proposes the use of an electromagnetic method for evaluation of coatings on stainless steel using a sensor with metamaterial lens and comparison of the results with those obtained by complementary methods.

  1. Structure of TiBN coatings deposited onto cemented carbides and sialon tool ceramics

    OpenAIRE

    L.A. Dobrzański; M. Staszuk; J. Konieczny; W. Kwaśny; M. Pawlyta

    2009-01-01

    Purpose: The aim of this paper was investigated structure of sintered carbides WC-Co type and sialon tool ceramics with wear resistance ternary coatings TiBN type deposited by cathodes arc evaporation process (CAE-PVD).Design/methodology/approach: Observation of fracture and topography studied coatings were done by scanning electron microscope. Chemical composition was determine by energy dispersive spectrometry (EDS) method. Thin foils of substrates and coatings by transmission electron micr...

  2. Preparation and Characterization of Nanotitanium Dioxide Coating Film Doped with Fe3+ Ions on Porous Ceramic

    Institute of Scientific and Technical Information of China (English)

    Kejing Xu

    2005-01-01

    The nanotitanium dioxide (TiO2) photocatalytic and porous ceramic filtering technique is one of the advanced methods to effectively treat organic wastewater. The TiO2 sol doped with Fe3+ ions was prepared by sol-gel processing. The influences of the process conditions of coating nanophotocatalytic material-Fe3+-TiO2 film on the surface of porous ceramic filter by dipping-lift method on the performance of porous ceramic filter were studied. The porous ceramic filters have two functions at the same time,filtration and photocatalytic degradation. The results of this study showed that the pH and viscosity of the sol,amount of Fe3+ ions doped as well as the coating times greatly affect the quality of coating film,the performance parameters and the photocatalytic activity of the porous ceramic filter. When the pH of the sol is 3-4,the viscosity is about 6 mPa·S,the amount of doped Fe3+ ions is about 2.0 g/L,the porous ceramic filter has been shown to have the best filtering performance and photocatalytic activity. In this condition,the porosity of porous ceramic is about 42.5%,the pore diameter is 8-10μm. The degradation of methyl-orange is 74.76% under lighting for 120 min.

  3. The characterization of an oxide interfacial coating for ceramic matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Coons, Timothy P., E-mail: tpcoons@gmail.com [Department of Chemistry, Unit 3060, University of Connecticut, 55 North Eagleville Road, Storrs, CT 06269-3060 (United States); Reutenauer, Justin W.; Mercado, Andrew [Department of Chemistry, Unit 3060, University of Connecticut, 55 North Eagleville Road, Storrs, CT 06269-3060 (United States); Kmetz, Michael A. [Pratt and Whitney, 400 Main Street M/S 114-43, East Hartford, CT 06108 (United States); Suib, Steven L. [Department of Chemistry, Unit 3060, University of Connecticut, 55 North Eagleville Road, Storrs, CT 06269-3060 (United States)

    2013-06-20

    This work focused on the use of metal organic chemical vapor deposition (MOCVD) to deposit a zinc oxide (ZnO) coating on ceramic fibers as an interfacial system for continuous fiber reinforced ceramic matrix composites (CFR-CMCs). ZnO coatings were deposited on ceramic grade (CG) Nicalon{sup ™}, Hi-Nicalon{sup ™}, and Hi-Nicalon{sup ™} Type S fabric by the thermal decomposition of zinc acetate dihydrate in a low pressure hot wall CVD reactor. A duplex SiO{sub 2} coating was also deposited in order to protect the ZnO layer from the reducing conditions during composite fabrication. Tow testing was used to evaluate the effect of the ZnO coating on the strength retention of the ceramic fabrics. Single strand unidirectional mini composites were fabricated by infiltrating SiC into the ZnO/SiO{sub 2} duplex coated tows in order to understand the interfacial properties of the ZnO coating. The mini composite utilizing Hi-Nicalon{sup ™} Type S produced the highest ultimate tensile strength (UTS) of 330 MPa. The coated fabrics and the mini composites were characterized using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and scanning Auger microscopy (SAM)

  4. Inelastic constitutive equation of plasma-sprayed ceramic thermal barrier coatings

    Institute of Scientific and Technical Information of China (English)

    Masayuki ARAI

    2011-01-01

    Ceramic thermal barrier coatings (TBCs) are a very important technology for protecting the hot parts of gas turbines (GTs) from a high-temperature environment. The coating stress generated in the operation of GTs brings cracking and peeling damage to the TBCs. Thus, it is necessary to evaluate precisely such coating stress in a TBC system. We have obtained a stress-strain curve for a freestanding ceramic coat specimen peeled from a TBC coated substrate by conducting the bending test. The test results have revealed that the ceramic coating deforms nonlinearly with the applied loading. In this study, an inelastic constitutive equation for the ceramic thermal barrier coatings deposited by APS is developed. The obtained results are as follows: (1) the micromechanics-based constitutive equation was formulated with micro crack density formed at splat boundary, and (2) it was shown that the numerical results for a nonlinearly deformed beam simulated by the developed constitutive equation agreed with the experimental results obtained by cantilever bending tests.

  5. Microstructures and Mechanical Properties of Ceramic/Metal Gradient Thermal Barrier Coatings

    Institute of Scientific and Technical Information of China (English)

    XIAO Jin-sheng; JIANG Bing; LIU Jie; HUANG Shi-yong

    2003-01-01

    The ceramic/metal gradient thermal barrier coatings (CMGTBCs) which combined the conceptions of thermal barrier coatings ( TBG ) and functional gradient materials ( FGMs ) are investigated. The structure model studied in this paper is a general model which includes four different layers: pure ceramic layer , ceramic/metal gradient layer, pure metal layer, and substrate layer. The microstructures of gradient layer have different ceramics and metal volume fraction profile along with the direction of thickness. The profile function used to describe the gradient microstructures can be expressed in power-law or polynomial expression. The mechanical properties of CMGTBCs are obtained by means of microscopic mechanics. As special cases, the interactive solutions are given by Mori- Tanaka method, and the non- interactive solutions by dilute solution. The Young's modulus calculated by these methods are compared with those by other methods , e g, the rule of mixtures.

  6. Producing Durable Continuously Reinforced Concrete Pavement using Glass-ceramic Coated Reinforcing Steel

    Science.gov (United States)

    2010-02-01

    Portland cement is manufactured by firing the clinker at 1400 C Enamel application produces no changes BUILDING STRONG® Treatment Average Peak...ceramic Coated Reinforcing Steel 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER... transition zone at the surface of the reinforcement steel is often the most permeable part of the concrete BUILDING STRONG® Schematic of Ceramic

  7. Preparation of cross-sectional specimens of ceramic thermal barrier coatings for transmission electron microscopy.

    Science.gov (United States)

    Unal, O; Heuer, A H; Mitchell, T E

    1990-04-01

    During the microstructural examination of ceramic thermal barrier coatings by transmission electron microscopy (TEM), initial efforts for the preparation of cross-sectional thin foils from interface regions by conventional means were mostly failures. Delamination of the Y2O3-stabilized ZrO2 ceramic coating from the nickel-base alloy substrate sometimes occurred during fine polishing at around 80 microns thickness but mostly occurred during dimpling. Because of this sensitivity, special techniques for mechanical handling were developed so that ion milling could give thin enough regions of the metal-ceramic interface. TEM showed convincingly that the highly fragile nature of the coatings is in fact due to the extensive porosity at the interface developed as a result of heat treatment.

  8. Gas turbine ceramic-coated-vane concept with convection-cooled porous metal core

    Science.gov (United States)

    Kascak, A. F.; Liebert, C. H.; Handschuh, R. F.; Ludwig, L. P.

    1981-01-01

    Analysis and flow experiments on a ceramic-coated-porous-metal vane concept indicated the feasibility, from a heat transfer standpoint, of operating in a high-temperature (2500 F) gas turbine cascade facility. The heat transfer and pressure drop calculations provided a basis for selecting the ceramic layer thickness (to 0.08 in.), which was found to be the dominant factor in the overall heat transfer coefficient. Also an approximate analysis of the heat transfer in the vane trailing edge revealed that with trailing-edge ejection the ceramic thickness could be reduced to (0.01 in.) in this portion of the vane.

  9. A novel processing of carbon nanotubes grown on molecular sieve coated porous ceramics

    Science.gov (United States)

    Mazumder, Sangram; Sarkar, Naboneeta; Park, Jung Gyu; Zhao, Wei; Kim, Sukyoung; Kim, Ik Jin

    2015-08-01

    The present study focuses on the growth of carbon nanotubes (CNTs) on Fe-containing zeolites coated porous ceramics by implementing three different and independent techniques, successively. Direct foaming-derived porous ceramics were subjected to hydrothermal reaction for on-site growth of NaA zeolites within it. The porous ceramics-zeolite composite was subjected to ion-exchange reaction to obtain the catalyst for CNT synthesis. Multi-walled CNTs (MWCNTs) were grown by catalytic chemical vapour deposition (CCVD) process using acetylene as carbon source. Microstructural, thermogravimetric and spectroscopic analyses showed distinctive differences in terms of hollow structural feature, yield and crystallinity of the MWCNTs with different reaction temperatures.

  10. Dense and half-dense NiZnCo ferrite ceramics: Their respective relevance for antenna downsizing, according to their dielectric and magnetic properties at microwave frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Mattei, J.-L., E-mail: mattei@univ-brest.fr; Chevalier, A. [Lab-STICC, Université de Bretagne Occidentale, CS 93837, 6 Avenue Le Gorgeu, 29238 Brest Cedex 3 (France); Le Guen, E. [Lab-STICC, Université de Bretagne Occidentale, CS 93837, 6 Avenue Le Gorgeu, 29238 Brest Cedex 3 (France); IETR, Université de Rennes 1, 263 Avenue General Leclerc, 35042 Rennes Cedex (France)

    2015-02-28

    Spinel ferrite Ni{sub 0.5}Zn{sub 0.3}Co{sub 0.2}Fe{sub 1.98}O{sub 4−x} nanoparticles were synthesized by co-precipitation method, and samples were realized by moulding and annealing at key temperatures (T{sub M} = 800 °C, 900 °C, 1050 °C, determined beforehand through shrinkage measurements) going with calcining and sintering processes. Annealing at 800 °C and 900 °C led to half-dense ceramics (porosity ∼50 vol. %), whereas bulky ferrite was obtained after annealing at 1050 °C. Elemental analysis, X-ray diffraction and ion chromatography analysis were performed. Complex dielectric permittivity (ε*) and magnetic permeability (μ*) were investigated up to 6 GHz. With increasing T{sub M}, a decreasing amount of Fe{sup 2+} was observed, going with increasing sample density. Coupled effects of the Fe{sup 2+} concentration and of the porosity, both on dielectric and magnetic properties, were chiefly investigated and discussed. The materials show almost constant permittivities (ε′ = 5.0, 6.0, and 14.8 for T{sub M} = 800 °C, 900 °C and 1050 °C, respectively). The bulk value at f = 1 GHz (ε′ = 14.8) can be interpreted well according to Shannon's theory. The permittivities of the half-dense ceramics are discussed on the basis of Bruggeman's Effective Medium Theory. The materials annealed at 800 °C and 900 °C show almost constant magnetic permeabilities in the frequency range from 0.2 to 1 GHz (μ′ = 3.4 and 6.0 for T{sub M} = 800 °C and 900 °C). The observed permeability behavior is typical of monodomain particles, except for the sample annealed at 1050 °C, for which domain wall contribution to μ* is suspected because of non-negligible losses at low frequency (μ″ = 1.3–1.8 at f < 0.3 GHz). This finding is supported by estimations of the upper and lower values for the critical grain size, on the basis of Brown–Van der Zaag's theory. Facing bulk ceramics

  11. Thermomechanical and Environmental Durability of Environmental Barrier Coated Ceramic Matrix Composites Under Thermal Gradients

    Science.gov (United States)

    Zhu, Dongming; Bhatt, Ramakrishna T.; Harder, Bryan

    2016-01-01

    This paper presents the developments of thermo-mechanical testing approaches and durability performance of environmental barrier coatings (EBCs) and EBC coated SiCSiC ceramic matrix composites (CMCs). Critical testing aspects of the CMCs will be described, including state of the art instrumentations such as temperature, thermal gradient, and full field strain measurements; materials thermal conductivity evolutions and thermal stress resistance; NDE methods; thermo-mechanical stress and environment interactions associated damage accumulations. Examples are also given for testing ceramic matrix composite sub-elements and small airfoils to help better understand the critical and complex CMC and EBC properties in engine relevant testing environments.

  12. Finite Element Analysis of Thermal Stresses in Ceramic/Metal Gradient Thermal Barrier Coatings

    Institute of Scientific and Technical Information of China (English)

    MING Pingshun; XIAO Jinsheng; LIU Jie; ZHOU Xiaoqin

    2005-01-01

    This paper studied the thermal stresses of ceramic/metal gradient thermal barrier coating which combines the conceptions of ceramic thermal barrier coating (TBC) and functionally gradient material (FGM). Thermal stresses and residual thermal stresses were calculated by an ANSYS finite element analysis software. Negative thermal expansion coefficient method was proposed and element birth and death method was applied to analyze the residual thermal stresses which have non-uniform initial temperature field. The numerical results show a good agreement with the analytical results and the experimental results.

  13. Survey of coatings for solar collectors. [ceramic enamels and chromium

    Science.gov (United States)

    Mcdonald, G. E.

    1974-01-01

    Ceramic enamel is found to be more solar selective, (i.e., has high solar absorptance in combination with low infrared emittance) than organic enamel, but neither is as solar selective as black chrome, black copper, black zinc, or black nickel. Ceramic enamel is matched only by black chrome in durability and wide availability. Ceramic enamel and organic enamel have approximately the same cost, and both are currently slightly lower in cost than black chrome, black copper, or black zinc. Black nickel is relatively unavailable and, because of that, realistic cost comparisons are not possible.

  14. Corrosion properties of zirconium-based ceramic coatings for micro-bearing and biomedical applications

    Science.gov (United States)

    Walkowicz, J.; Zavaleyev, V.; Dobruchowska, E.; Murzynski, D.; Donkov, N.; Zykova, A.; Safonov, V.; Yakovin, S.

    2016-03-01

    Ceramic oxide ZrO2 and oxynitride ZrON coatings are widely used as protective coatings against diffusion and corrosion. The enhancement of the coatings' mechanical properties, as well as their wear and corrosion resistance, is very important for their tribological performance. In this work, ZrO2 and ZrON coatings were deposited by magnetron sputtering on stainless steel (AISI 316) substrates. The adhesion, hardness and elastic properties were evaluated by standard methods. The surface structure of the deposited coatings was observed by electron scanning microscopy (SEM) and atomic force microscopy (AFM). The composition of the coatings was analyzed by X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDS). The corrosion resistance properties were evaluated using the potentiodynamic method. The results show that the corrosion parameters are significantly increased in the cases of both oxynitride and oxide coatings in comparison with the stainless steel (AISI 316) substrates.

  15. Influence of contamination on resin bond strength to nano-structured alumina-coated zirconia ceramic.

    Science.gov (United States)

    Zhang, Shanchuan; Kocjan, Andraz; Lehmann, Frank; Kosmac, Tomaz; Kern, Matthias

    2010-08-01

    The purpose of this study was to evaluate the influence of contamination and subsequent cleaning on the bond strength and durability of an adhesive resin to nano-structured alumina-coated zirconia ceramic. Zirconia ceramic disks were coated with nano-structured alumina, utilizing the hydrolysis of aluminum nitride powder. After immersion in saliva or the use of a silicone disclosing agent, specimens were cleaned with phosphoric acid etching or with tap water rinsing only. Uncontaminated specimens served as controls. Plexiglas tubes filled with composite resin were bonded with a phosphate monomer [10-methacryloxydecyl-dihydrogenphosphate (MDP)]-containing resin (Panavia 21). Subgroups of eight specimens each were stored in distilled water at 37 degrees C, either for 3 d without thermal cycling (TC) or for 150 d with 37,500 thermal cycles from 5 to 55 degrees C. The tensile bond strength (TBS) was determined using a universal testing machine at a crosshead speed of 2 mm min(-1). The topography of the debonded surface was scrutinized for fractographic features, utilizing both optical and scanning electron microscopy. The TBS to uncontaminated nano-structured alumina-coated zirconia ceramic was durable, while contamination significantly reduced the TBS. Phosphoric acid cleaning was effective in removal of saliva contamination from the coated bonding surface but was not effective in removal of the silicone disclosing agent. Nano-structured alumina coating improves resin bonding to zirconia ceramic and eliminates the need for air-abrasion before bonding.

  16. Structure and tensile/wear properties of microarc oxidation ceramic coatings on aluminium alloy

    Institute of Scientific and Technical Information of China (English)

    魏同波; 阎逢元; 刘维民; 田军

    2004-01-01

    Thick and hard ceramic coatings were prepared on the Al-Cu-Mg alloy by microarc oxidation in alkali-silicate electrolytic solution. The thickness and microhardness of the oxide coatings were measured. The influence of current density on the growth rate of the coating was examined. The microstructure and phase composition of the coatings were investigated by means of scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. Moreover, the tensile strength of the Al alloy before and after microarc oxidation treatment were tested,and the fractography and morphology of the oxide coatings were observed using scanning electron microscope. It is found that the current density considerably influences the growth rate of the microarc oxidation coatings. The oxide coating is mainly composed of α-Al2 O3 and γ-Al2 O3, while high content of Si is observed in the superficial layer of the coating. The cross-section microhardness of 120 μm thick coating reaches the maximum at distance of 35 μm from the substrate/coating interface. The tensile strength and elongation of the coated Al alloy significantly decrease with increasing coating thickness. The microarc oxidation coatings greatly improve the wear resistance of Al alloy,but have high friction coefficient which changes in the range of 0.7 - 0.8. Under grease lubricating, friction coefficient is only 0.15 and wear loss is less than 1/10 of the loss under dry friction.

  17. Hydroxyapatite coatings deposited by liquid precursor plasma spraying: controlled dense and porous microstructures and osteoblastic cell responses

    Energy Technology Data Exchange (ETDEWEB)

    Huang Yi; Song Lei; Liu Xiaoguang; Xiao Yanfeng; Wu Yao; Chen Jiyong; Wu Fang; Gu Zhongwei, E-mail: fangwu0808@yahoo.co, E-mail: fwu@scu.edu.c [National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064 (China)

    2010-12-15

    Hydroxyapatite coatings were deposited on Ti-6Al-4V substrates by a novel plasma spraying process, the liquid precursor plasma spraying (LPPS) process. X-ray diffraction results showed that the coatings obtained by the LPPS process were mainly composed of hydroxyapatite. The LPPS process also showed excellent control on the coating microstructure, and both nearly fully dense and highly porous hydroxyapatite coatings were obtained by simply adjusting the solid content of the hydroxyapatite liquid precursor. Scanning electron microscope observations indicated that the porous hydroxyapatite coatings had pore size in the range of 10-200 {mu}m and an average porosity of 48.26 {+-} 0.10%. The osteoblastic cell responses to the dense and porous hydroxyapatite coatings were evaluated with human osteoblastic cell MG-63, in respect of the cell morphology, proliferation and differentiation, with the hydroxyapatite coatings deposited by the atmospheric plasma spraying (APS) process as control. The cell experiment results indicated that the heat-treated LPPS coatings with a porous structure showed the best cell proliferation and differentiation among all the hydroxyapatite coatings. Our results suggest that the LPPS process is a promising plasma spraying technique for fabricating hydroxyapatite coatings with a controllable microstructure, which has great potential in bone repair and replacement applications.

  18. Cross-sectional AEM preparation technique for ceramic-coated WC-Co cutting tools.

    Science.gov (United States)

    Ostreicher, K; Sung, C

    1993-04-15

    The preparation of cross-sectional specimens for AEM studies of materials such as ceramic coated tungsten carbide presents some unique problems. Pieces joined by the use of epoxides often separate at the interface between the WC and ceramic coating during the initial mechanical grinding and subsequent thinning process as a result of the vibration and physical strain placed on the sample. These problems have been overcome through the use of a preparation process which essentially encapsulates the sample within the confines of an epoxy filled quartz tube. This preparation process has allowed for facile AEM cross-sectional analysis of TiN/TiCN coatings on WC-Co substrates, and has revealed two distinct grain morphologies within the TiCN coating.

  19. Ceramic coating of metal by laser heat treatment at ambient pressure and temperature

    Science.gov (United States)

    Picouet, Pierre A.; McStay, Daniel; Hunter, Catherine; Tonge, Kenneth

    2000-02-01

    Initial results for a new laser based procedure to make ceramic coatings on ferrous metals are described. The procedure is performed at ambient temperature and pressure to avoid the use of a vacuum chamber. An Nd:YAG laser beam (1064 nm) coupled to a mechanical scanner is used to produce coating. The coating precursor materials are sprayed onto the metal sample before the laser-generated heat treatment. A jet of argon gas is used to avoid oxidation of the metallic substrate. The principal ingredients of the coating precursor are sodium tetraborate and a natural clay mineral. The product is a glassy ceramic. The product has been characterized by scanning electron microscopy, optical microscopy and hardness and adhesion tests. The results indicate that the surface material is a micrometric, single layer which adheres to the metal surface.

  20. Key Durability Issues with Mullite-Based Environmental Barrier Coatings for Si-Based Ceramics

    Science.gov (United States)

    Lee, Kang N.

    2000-01-01

    Plasma-sprayed mullite (3Al2O3.2SiO2) and mullite/yttria-stabilized-zirconia (YSZ) dual layer coatings have been developed to protect silicon -based ceramics from environmental attack. Mullite-based coating systems show excellent durability in air. However, in combustion environments, corrosive species such as molten salt or water vapor penetrate through cracks in the coating and attack the Si-based ceramics along the interface. Thus the modification of the coating system for enhanced crack-resistance is necessary for long-term durability in combustion environments. Other key durability issues include interfacial contamination and coating/substrate bonding. Interfacial contamination leads to enhanced oxidation and interfacial pore formation, while a weak coating/substrate bonding leads to rapid attack of the interface by corrosive species, both of which can cause a premature failure of the coating. Interfacial contamination can be minimized by limiting impurities in coating and substrate materials. The interface may be modified to improve the coating/substrate bond.

  1. Key Durability Issues with Mullite-Based Environmental Barrier Coatings for Si-Based Ceramics

    Science.gov (United States)

    Lee, Kang N.

    2000-01-01

    Plasma-sprayed mullite (3Al2O3.2SiO2) and mullite/yttria-stabilized-zirconia (YSZ) dual layer coatings have been developed to protect silicon -based ceramics from environmental attack. Mullite-based coating systems show excellent durability in air. However, in combustion environments, corrosive species such as molten salt or water vapor penetrate through cracks in the coating and attack the Si-based ceramics along the interface. Thus the modification of the coating system for enhanced crack-resistance is necessary for long-term durability in combustion environments. Other key durability issues include interfacial contamination and coating/substrate bonding. Interfacial contamination leads to enhanced oxidation and interfacial pore formation, while a weak coating/substrate bonding leads to rapid attack of the interface by corrosive species, both of which can cause a premature failure of the coating. Interfacial contamination can be minimized by limiting impurities in coating and substrate materials. The interface may be modified to improve the coating/substrate bond.

  2. Sputter-deposited metallic and ceramic coatings for heat engines. Work performed from October 1980 to September 1983. [CoCrAlY; ZrO/sub 2/; Al/sub 2/O/sub 3/; Ni-SiC; quartz-SiC

    Energy Technology Data Exchange (ETDEWEB)

    Prater, J.T.; Moss, R.W.

    1984-04-01

    Progress in the development of metallic and ceramic coatings with improved high-temperature corrosion and erosion/wear resistance is reported. The objective was to develop coatings that would insure that future heat engines, notably gas turbines and diesels, would be able to operate efficiently on degraded fuel supplies. The majority of coatings investigated were prepared by sputter deposition. Research on sputter-deposited CoCrAlY coatings was directed at improving their low-temperature, hot corrosion resistance by introducing composition gradients and adding platinum. Studies on sputter-deposited ZrO/sub 2/ and Al/sub 2/O/sub 3/ coatings were conducted to improve the thermal cycling resistance of ceramic deposits on metal substrates by using combinations of graded transition layers, columnar ceramic structures, and dense sealing layers. Preliminary results on plasma-sprayed Ni-SiC and quartz-SiC coatings that showed good wear and oxidation resistance are also reported.

  3. Evolution of residual stresses in micro-arc oxidation ceramic coatings on 6061 Al alloy

    Science.gov (United States)

    Shen, Dejiu; Cai, Jingrui; Guo, Changhong; Liu, Peiyu

    2013-11-01

    Most researches on micro-arc oxidation mainly focus on the application rather than discovering the evolution of residual stresses. However, residual stresses in the surface coatings of structural components have adverse effects on their properties, such as fatigue life, dimensional stability and corrosion resistance, etc. The micro-arc oxidation ceramic coatings are produced on the surfaces of 6061 aluminum alloy by a homemade asymmetric AC type of micro-arc oxidation equipment of 20 kW. A constant current density of 4.4±0.1 A/dm2 and a self-regulated composite electrolyte are used. The micro-arc oxidation treatment period ranges from 10 min to 40 min, and the thickness of the ceramic coatings is more than 20 μm. Residual stresses attributed to γ-Al2O3 constituent in the coatings at different micro-arc oxidation periods are analyzed by an X-ray diffractometer using the sin2 ψ method. The analysis results show that the residual stress in the ceramic coatings is compressive in nature, and it increases first and then decreases with micro-arc oxidation time increase. The maximum stress value is 1 667±20 MPa for period of 20 min. Through analyzing the coating thickness, surface morphology and phase composition, it is found that the residual stress in the ceramic coatings is linked closely with the coating growth, the phase composition and the micro cracks formed. It is also found that both the heat treatment and the ultrasonic action release remarkably the residual compressive stress. The heat treatment makes the residual compressive stress value decrease 1 378 MPa. The ultrasonic action even alters the nature of the residual stress, making the residual compressive stress change into a residual tensile stress.

  4. Advanced Porous Coating for Low-Density Ceramic Insulation Materials

    Science.gov (United States)

    Leiser, Daniel B.; Churchward, Rex; Katvala, Victor; Stewart, David; Balter, Aliza

    1988-01-01

    The need for improved coatings on low-density reusable surface insulation (RSI) materials used on the space shuttle has stimulated research into developing tougher coatings. The processing of a new porous composite "coating" for RST called toughened unipiece fibrous insulation Is discussed. Characteristics including performance in a simulated high-speed atmospheric entry, morphological structure before and after this exposure, resistance to Impact, and thermal response to a typical heat pulse are described. It is shown that this coating has improved impact resistance while maintaining optical and thermal properties comparable to the previously available reaction-cured glass coating.

  5. Entrapment of subtilisin in ceramic sol-gel coating for antifouling applications.

    Science.gov (United States)

    Regina, Viduthalai Rasheedkhan; Søhoel, Helmer; Lokanathan, Arcot Raghupathi; Bischoff, Claus; Kingshott, Peter; Revsbech, Niels Peter; Meyer, Rikke Louise

    2012-11-01

    Enzymes with antifouling properties are of great interest in developing nontoxic antifouling coatings. A bottleneck in developing enzyme-based antifouling coatings is to immobilize the enzyme in a suitable coating matrix without compromising its activity and stability. Entrapment of enzymes in ceramics using the sol-gel method is known to have several advantages over other immobilization methods. The sol-gel method can be used to make robust coatings, and the aim of this study was to explore if sol-gel technology can be used to develop robust coatings harboring active enzymes for antifouling applications. We successfully entrapped a protease, subtilisin (Savinase, Novozymes), in a ceramic coating using a sol-gel method. The sol-gel formulation, when coated on a stainless steel surface, adhered strongly and cured at room temperature in less than 8 h. The resultant coating was smoother and less hydrophobic than stainless steel. Changes in the coating's surface structure, thickness and chemistry indicate that the coating undergoes gradual erosion in aqueous medium, which results in release of subtilisin. Subtilisin activity in the coating increased initially, and then gradually decreased. After 9 months, 13% of the initial enzyme activity remained. Compared to stainless steel, the sol-gel-coated surfaces with active subtilisin were able to reduce bacterial attachment of both Gram positive and Gram negative bacteria by 2 orders of magnitude. Together, our results demonstrate that the sol-gel method is a promising coating technology for entrapping active enzymes, presenting an interesting avenue for enzyme-based antifouling solutions.

  6. In-situ measurement of elastic modulus for ceramic top-coat at high temperature

    Institute of Scientific and Technical Information of China (English)

    齐红宇; 周立柱; 马海全; 杨晓光; 李旭

    2008-01-01

    The ceramic thermal barrier coatings (TBCs) play an increasingly important in advanced gas turbine engines because of their ability to further increase the engine operating temperature and reduce the cooling, thus help achieve future engine low emission, high efficiency and improve the reliability goals. Currently, there are two different processes such as the plasma spraying (PS) and the electron beam-physical vapor deposition (EB-PVD) techniques. The PS coating was selected to test the elastic modulus. Using the nanoindentation and resonant frequency method, the mechanical properties of ceramic top-coat were measured in-situ. According to the theory of the resonant frequency and composite beam, the testing system was set up including the hardware and software. The results show that the accurate characterization of the elastic properties of TBCs is important for stress-strain analysis and failure prediction. The TBCs systems are multi-layer material system. It is difficult to measure the elastic modulus of top-coat by tensile method. The testing data is scatter by nanoindentation method because of the microstructure of the ceramic top-coat. The elastic modulus of the top-coat between 20?1 150 ℃ is obtained. The elastic modulus is from 2 to 70 GPa at room temperature. The elastic modulus changes from 62.5 GPa to 18.6 GPa when the temperature increases from 20 ℃ to 1 150 ℃.

  7. Structure and in vitro bioactivity of ceramic coatings on magnesium alloys by microarc oxidation

    Science.gov (United States)

    Yu, Huijun; Dong, Qing; Dou, Jinhe; Pan, Yaokun; Chen, Chuanzhong

    2016-12-01

    Magnesium and its alloys have the potential to serve as lightweight, degradable, biocompatible and bioactive orthopedic implants for load-bearing applications. However, severe local corrosion attack and high corrosion rate have prevented their further clinical use. Micro-arc oxidation (MAO) is proved to be a simple, controllable and efficient electrochemistry technique that can prepare protective ceramic coatings on magnesium alloys. In this paper, electrolyte containing silicate salts was used for microarc oxidation to form ceramic bioactive coatings on the ZK61 alloy substrate. The structure characteristics and element distributions of the coating were investigated by XRD, TEM, SEM and EPMA. The MAO samples were immersed in simulated body fluid (SBF) for 7 and 14 days, respectively. The surface characteristic of the immersed coatings was investigated by Fourier-transform infrared (FTIR) spectroscopy. The results show that these MAO coatings have low crystallinity and are mainly composed of MgO, Mg2SiO4 and Mg2Si2O6. The coating surface is porous. During the SBF immersion period, the nucleation and precipitation of bone-like apatites occur on the MAO coating surface. The corrosion resistance of the substrate is improved by the MAO coatings.

  8. PTA clad (Cr,Fe)7C3/γ-Fe in situ ceramal composite coating

    Institute of Scientific and Technical Information of China (English)

    Junbo Liu; Limei Wang; Jihua Huang

    2006-01-01

    A wear-resistant (Cr, Fe)7C3/γ-Fe in situ ceramal composite coating was fabricated on the substrate of 0.45wt%C carbon steel by a plasma-transferred arc cladding process using the Fe-Cr-C elemental powder blends. The microstructure, microhardness, and dry-sliding wear resistance of the coating were evaluated. The results indicate that the microstructure of the coating, which was composed of (Cr, Fe)7C3 primary phase uniformly distributed in the γ-Fe, and the (Cr, Fe)7C3 eutectic matrix was metallurgically bonded to the 0.45wt%C carbon steel substrate. From substrate to coating, the microstructure of the coating exhibited an evident epitaxial growth character. The coating, indehiscent and tack-free, had high hardness and appropriate gradient. It had excellent wear resistance under the dry sliding wear test condition.

  9. Effects of single pulse energy on the properties of ceramic coating prepared by micro-arc oxidation on Ti alloy

    Science.gov (United States)

    Wang, Jun-Hua; Wang, Jin; Lu, Yan; Du, Mao-Hua; Han, Fu-Zhu

    2015-01-01

    The effects of single pulse energy on the properties of ceramic coating fabricated on a Ti-6Al-4V alloy via micro-arc oxidation (MAO) in aqueous solutions containing aluminate, phosphate, and some additives are investigated. The thickness, micro-hardness, surface and cross-sectional morphology, surface roughness, and compositions of the ceramic coating are studied using eddy current thickness meter, micro-hardness tester, JB-4C Precision Surface roughness meter, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Single pulse energy remarkably influences the ceramic coating properties. The accumulative time of impulse width is an important parameter in the scientific and rational measurement of the film forming law of ceramic coating. The ceramic coating thickness approximately linearly increases with the cumulative time of impulse width. Larger impulse width resulted in higher single pulse energy, film forming rates and thicker ceramic coating thickness. The sizes of oxide particles, micro-pores and micro-cracks slightly increase with impulse width and single pulse energy. The main surface conversion products generated during MAO process in aqueous solutions containing aluminate are rutile TiO2, anatase TiO2, and a large amount of Al2TiO5. The effects of single pulse energy on the micro-hardness and phase composition of ceramic coating are not as evident as those of frequency and duty cycle.

  10. Process engineering of ceramic composite coatings for fuel cell systems

    Energy Technology Data Exchange (ETDEWEB)

    Li, G.; Kim, H.; Chen, M.; Yang, Q.; Troczynski, T. [British Columbia Univ., Vancouver, BC (Canada). Dept. of Metals and Materials Engineering

    2003-07-01

    Researchers at UBCeram at the Department of Metals and Materials Engineering at the University of British Columbia have developed a technology to chemically bond composite sol-gel (CB-CSG) coating onto metallic surfaces of complex or concave shapes. The process has been optimized for electrically resistive coatings and corrosion-resistant coatings. The CSG is sprayed onto metallic surfaces and is heat-treated at 300 degrees C to partially dehydrate the hydroxides. The CSG film is then chemically bonded through reaction of active alumina with metal phosphates, such as aluminium phosphate. A new chromate-free process is being developed to address the issue of coatings porosity. The electrodeposition technique involves polymer particles mixed with suspended fine alumina particles which are co-deposited by electrophoretic means or by electrocoagulation. The composite e-coatings have excellent mechanical properties and are being considered as a protective coating for various components of fuel cell systems. 9 refs., 7 figs.

  11. Single-step fabrication of nanolamellar structured oxide ceramic coatings by metal-organic chemical vapor deposition.

    Science.gov (United States)

    Eils, Nadine K; Mechnich, Peter; Keune, Hartmut; Wahl, Georg; Klages, Claus-Peter

    2011-09-01

    Oxide ceramic coatings in the system Y2O3-Al2O3-ZrO2 were fabricated in laboratory scale by using a MOCVD unit. A hot wall reactor was used along with different precursor feeding systems. Most experiments were carried out by using powder flash evaporation including a screw feeder for precursor powder delivery. For comparison, further samples were fabricated by using band flash evaporation and continuous evaporation from a crucible. Oxygen was used in all cases as reactant gas. Aluminium-tris-2,4-pentanedione (Al(acac)3), yttrium-tris-2,2,6,6-tetramethyl-3,5-heptanedione (Y(thd)3) and zirconium-tetrakis-2,2,6,6-tetramethyl-3,5-heptanedione (Zr(thd)4) were applied as metal-organic precursors because of their similar vaporization behaviour under the given conditions. The coating stoichiometry was varied from pure alumina to complex ternary compositions in the system Y2O3-Al2O3-ZrO2. Both kinds of ternary coatings fabricated by using flash evaporation methods show a nanolamellar microstructure in the as deposited state. Heat treating experiments at 1200 degrees C for up to 5 days enhance the lamellar character of the coating deposited by using powder flash evaporation. The lamellar microstructure is due to alternating YSZ enriched layers and YAG enriched layers in this state. However, the coating fabricated by using band flash evaporation shows a dense interpenetrating network of YSZ and YAG after heat treating instead of a lamellar microstructure observed in the as deposited state.

  12. Sealed glass coating of high temperature ceramic superconductors

    Science.gov (United States)

    Wu, Weite; Chu, Cha Y.; Goretta, Kenneth C.; Routbort, Jules L.

    1995-01-01

    A method and article of manufacture of a lead oxide based glass coating on a high temperature superconductor. The method includes preparing a dispersion of glass powders in a solution, applying the dispersion to the superconductor, drying the dispersion before applying another coating and heating the glass powder dispersion at temperatures below oxygen diffusion onset and above the glass melting point to form a continuous glass coating on the superconductor to establish compressive stresses which enhance the fracture strength of the superconductor.

  13. Salt spray corrosion test of micro-plasma oxidation ceramic coatings on Ti alloy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Ceramic coatings were prepared on Ti-6Al-4V alloy in NaAlO2 solution by micro-plasma oxidation (MPO). The salt spray teste of tne coated samples and the substrates were carried out in a salt spray test machine. The phase composition and surface morphology of the coatings were investigated by XRD and SEM. Severe corrosion occurred on the substrate surface, while there were no obvious corrosion phenomena on the coated samples. The coatings were composed of Al2TiO5 and a little α-Al2O3 and rutile TiO2, and the salt spray test did not change the composition of the coatings. The weight loss rate of the coatings decreased with increasing MPO time because of the increase in density and thickness of the coatings. The surface morphology of the coatings was influenced by salt spray corrosion test Among the coated samples, the coating prepared for 2 h has the best corrosion resistance under salt spray test.

  14. Advanced Environmental Barrier Coating Development for SiC-SiC Ceramic Matrix Composite Components

    Science.gov (United States)

    Zhu, Dongming; Harder, Bryan; Bhatt, Ramakrishna; Kiser, Doug; Wiesner, Valerie L.

    2016-01-01

    This presentation reviews the NASA advanced environmental barrier coating (EBC) system development for SiCSiC Ceramic Matrix Composite (CMC) components for next generation turbine engines. The emphasis has been placed on the current design challenges of the 2700F environmental barrier coatings; coating processing and integration with SiCSiC CMCs and component systems; and performance evaluation and demonstration of EBC-CMC systems. This presentation also highlights the EBC-CMC system temperature capability and durability improvements through advanced compositions and architecture designs, as shown in recent simulated engine high heat flux, combustion environment, in conjunction with mechanical creep and fatigue loading testing conditions.

  15. Influencing factors of surface roughness of MAO ceramic coating on AZ91D

    Institute of Scientific and Technical Information of China (English)

    DI Shi-chun; PAN Ming-qiang; CHI Guan-xin

    2006-01-01

    To investigate the treating parameters' influence on the surface roughness of the MAO ceramic coating on AZ91D, experiments were implemented in the alkaline electrolyte by using a pulse power source with positive and negative pulse, and the surface roughness was measured and analyzed by using a Times roughness-meter and an optical microscope. The machining parameters' influencing rule on the coating surface roughness was investigated. The result indicates that the influence of all parameters is interactive, while the positive voltage and the electrolyte concentration, or increasing the frequency and the positive and negative voltage ratio are appropriate, the coating surface roughness will be improved.

  16. Residual Stresses in Microarc Oxidation Ceramic Coatings on Biocompatible AZ31 Magnesium Alloys

    Science.gov (United States)

    Gu, Yanhong; Xiong, Wenming; Ning, Chengyun; Zhang, Jing

    2012-06-01

    Ceramic coatings have been successfully prepared on biocompatible AZ31 magnesium alloy substrates using microarc oxidation (MAO) technique. Residual stresses attributed to the MgO constituent of the coatings at different oxidation voltages have been evaluated by x-ray diffraction using the sin2 ψ method. It is found that tensile residual stresses were present in the coatings, and they decreased from 1418 to 545 MPa as the oxidation voltages increased from 250 to 350 V. Correlations between the residual stresses and microstructural morphology have been discussed. The residual stress characteristics are attributed to the microcracks and the new phase formation during the MAO process.

  17. Advanced ceramic coating development for industrial/utility gas turbine applications

    Science.gov (United States)

    Andersson, C. A.; Lau, S. K.; Bratton, R. J.; Lee, S. Y.; Rieke, K. L.; Allen, J.; Munson, K. E.

    1982-01-01

    The effects of ceramic coatings on the lifetimes of metal turbine components and on the performance of a utility turbine, as well as of the turbine operational cycle on the ceramic coatings were determined. When operating the turbine under conditions of constant cooling flow, the first row blades run 55K cooler, and as a result, have 10 times the creep rupture life, 10 times the low cycle fatigue life and twice the corrosion life with only slight decreases in both specific power and efficiency. When operating the turbine at constant metal temperature and reduced cooling flow, both specific power and efficiency increases, with no change in component lifetime. The most severe thermal transient of the turbine causes the coating bond stresses to approach 60% of the bond strengths. Ceramic coating failures was studied. Analytic models based on fracture mechanics theories, combined with measured properties quantitatively assessed both single and multiple thermal cycle failures which allowed the prediction of coating lifetime. Qualitative models for corrosion failures are also presented.

  18. Durability of zirconia thermal-barrier ceramic coatings on air-cooled turbine blades in cyclic jet engine operation

    Science.gov (United States)

    Liebert, C. H.; Jacobs, R. E.; Stecura, S.; Morse, C. R.

    1976-01-01

    Thermal barrier ceramic coatings of stabilized zirconia over a bond coat of Ni Cr Al Y were tested for durability on air cooled turbine rotor blades in a research turbojet engine. Zirconia stabilized with either yttria, magnesia, or calcia was investigated. On the basis of durability and processing cost, the yttria stabilized zirconia was considered the best of the three coatings investigated.

  19. Nanocrystalline, superhard, ductile ceramic coatings for roller-cone bit bearings

    Energy Technology Data Exchange (ETDEWEB)

    Namavar, F.; Colter, P.; Karimy, H. [Spire Corp., Bedford, MA (United States)] [and others

    1997-12-31

    The established method for construction of roller bits utilizes carburized steel, frequently with inserted metal bearing surfaces. This construction provides the necessary surface hardness while maintaining other desirable properties in the core. Protective coatings are a logical development where enhanced hardness, wear resistance, corrosion resistance, and surface properties are required. The wear properties of geothermal roller-cone bit bearings could be further improved by application of protective ceramic hard coatings consisting of nanometer-sized crystallites. Nanocrystalline protective coatings provide the required combination of hardness and toughness which has not been available thus far using traditional ceramics having larger grains. Increased durability of roller-cone bit bearings will ultimately reduce the cost of drilling geothermal wells through increased durability.

  20. Preparation and characterization of TiO2 and Si-doped octacalcium phosphate composite coatings on zirconia ceramics (Y-TZP) for dental implant applications

    Science.gov (United States)

    Bao, Lei; Liu, Jingxiao; Shi, Fei; Jiang, Yanyan; Liu, Guishan

    2014-01-01

    In order to prevent the low temperature degradation and improve the bioactivity of zirconia ceramic implants, TiO2 and Si-doped octacalcium phosphate composite coating was prepared on zirconia substrate. The preventive effect on low temperature degradation and surface morphology of the TiO2 layer were studied. Meanwhile, the structure and property changes of the bioactive coating after doping Si were discussed. The results indicate that the dense TiO2 layer, in spite of some microcracks, inhibited the direct contact of the water vapor with the sample's surface and thus prevented the low temperature degradation of zirconia substrates. The acceleration aging test shows that the ratio of the monoclinic phase transition decreased from 10% for the original zirconia substrate to 4% for the TiO2-coated substrate. As to the Si-doped octacalcium phosphate coating prepared by biomimetic method, the main phase composition of the coating was octacalcium phosphate. The morphology of the coating was lamellar-like, and the surface was uniform and continuous with no cracks being observed. It is suggested that Si was added into the coating both through substituting for PO43- and doping as NaSiO3.

  1. Influence of heat treatment on bond strength and corrosion resistance of sol-gel derived bioglass-ceramic coatings on magnesium alloy.

    Science.gov (United States)

    Shen, Sibo; Cai, Shu; Xu, Guohua; Zhao, Huan; Niu, Shuxin; Zhang, Ruiyue

    2015-05-01

    In this study, bioglass-ceramic coatings were prepared on magnesium alloy substrates through sol-gel dip-coating route followed by heat treatment at the temperature range of 350-500°C. Structure evolution, bond strength and corrosion resistance of samples were studied. It was shown that increasing heat treatment temperature resulted in denser coating structure as well as increased interfacial residual stress. A failure mode transition from cohesive to adhesive combined with a maximum on the measured bond strength together suggested that heat treatment enhanced the cohesion strength of coating on the one hand, while deteriorated the adhesion strength of coating/substrate on the other, thus leading to the highest bond strength of 27.0MPa for the sample heat-treated at 450°C. This sample also exhibited the best corrosion resistance. Electrochemical tests revealed that relative dense coating matrix and good interfacial adhesion can effectively retard the penetration of simulated body fluid through the coating, thus providing excellent protection for the underlying magnesium alloy.

  2. Effects of single pulse energy on the properties of ceramic coating prepared by micro-arc oxidation on Ti alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jun-Hua [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023 (China); Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming 650500 (China); Wang, Jin [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control, Beijing 100084 (China); Lu, Yan [School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023 (China); Du, Mao-Hua [Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming 650500 (China); Han, Fu-Zhu, E-mail: hanfuzhu@mail.tsinghua.edu.cn [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control, Beijing 100084 (China)

    2015-01-01

    Highlights: • Single pulse energy remarkably influences the properties of ceramic coating prepared by MAO on Ti alloy. • The accumulative time of impulse width is an important parameter in the scientific and rational measurement of the film forming law of ceramic coating. • The ceramic coating thickness approximately linearly increases with the cumulative time of impulse width. • Larger impulse width resulted in higher single pulse energy, film forming rates and thicker ceramic coating thickness. • The effects of single pulse energy on the micro-hardness and phase composition of ceramic coating are not as evident as those of frequency and duty cycle. - Abstract: The effects of single pulse energy on the properties of ceramic coating fabricated on a Ti–6Al–4V alloy via micro-arc oxidation (MAO) in aqueous solutions containing aluminate, phosphate, and some additives are investigated. The thickness, micro-hardness, surface and cross-sectional morphology, surface roughness, and compositions of the ceramic coating are studied using eddy current thickness meter, micro-hardness tester, JB-4C Precision Surface roughness meter, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Single pulse energy remarkably influences the ceramic coating properties. The accumulative time of impulse width is an important parameter in the scientific and rational measurement of the film forming law of ceramic coating. The ceramic coating thickness approximately linearly increases with the cumulative time of impulse width. Larger impulse width resulted in higher single pulse energy, film forming rates and thicker ceramic coating thickness. The sizes of oxide particles, micro-pores and micro-cracks slightly increase with impulse width and single pulse energy. The main surface conversion products generated during MAO process in aqueous solutions containing aluminate are rutile TiO{sub 2}, anatase TiO{sub 2}, and a large amount of Al{sub 2}TiO{sub 5}. The effects of

  3. Formation and Characterization of Ceramic Nanocomposite Crystalline Coatings on Aluminium by Anodization

    Institute of Scientific and Technical Information of China (English)

    M.Mubarak Ali; V.Raj

    2013-01-01

    Ceramic nanocomposite coatings have been synthesized on aluminium by using lithium sulphate electrolyte with zirconium silicate additive by anodization.The effects of current density (CD) on microhardness,structure,composition and surface topography of the oxide layer formed at various CDs (0.1-0.25 A/cm2) have been studied.Crystalline coatings formed at 0.25 A/cm2 have been (width 95 nm) observed with a relatively uniform distribution confirmed by scanning electron microscopy.Additionally,the average microhardness value of ceramic nanocomposite coatings fabricated from lithium sulphate-zirconium silicate bath is approximately 8.5 times higher than that of the as-received aluminium.The surface statistics of the coatings is discussed in detail to explain the roughness and related parameters for better understanding.These observations demonstrate the importance of surface statistics in controlling the morphology of the coatings and its properties.From the X-ray diffraction investigations,it can be concluded that the formed nanocomposite coatings are crystalline in nature and that the crystallinity of the coatings decreases with increasing applied current density.

  4. Characterization of High-Velocity Single Particle Impacts on Plasma-Sprayed Ceramic Coatings

    Science.gov (United States)

    Kiilakoski, Jarkko; Lindroos, Matti; Apostol, Marian; Koivuluoto, Heli; Kuokkala, Veli-Tapani; Vuoristo, Petri

    2016-08-01

    High-velocity impact wear can have a significant effect on the lifetime of thermally sprayed coatings in multiple applications, e.g., in the process and paper industries. Plasma-sprayed oxide coatings, such as Cr2O3- and TiO2-based coatings, are often used in these industries in wear and corrosion applications. An experimental impact study was performed on thermally sprayed ceramic coatings using the High-Velocity Particle Impactor (HVPI) at oblique angles to investigate the damage, failure, and deformation of the coated structures. The impact site was characterized by profilometry, optical microscopy, and scanning electron microscopy (SEM). Furthermore, the connection between the microstructural details and impact behavior was studied in order to reveal the damage and failure characteristics at a more comprehensive level. Differences in the fracture behavior were found between the thermally sprayed Cr2O3 and TiO2 coatings, and a concept of critical impact energy is presented here. The superior cohesion of the TiO2 coating inhibited interlamellar cracking while the Cr2O3 coating suffered greater damage at high impact energies. The HVPI experiment has proven to be able to produce valuable information about the deformation behavior of coatings under high strain rates and could be utilized further in the development of wear-resistant coatings.

  5. Composite Coatings with Ceramic Matrix Including Nanomaterials as Solid Lubricants for Oil-Less Automotive Applications

    Directory of Open Access Journals (Sweden)

    Posmyk A.

    2016-06-01

    Full Text Available The paper presents the theoretical basis of manufacturing and chosen applications of composite coatings with ceramic matrix containing nanomaterials as a solid lubricant (AHC+NL. From a theoretical point of view, in order to reduce the friction coefficient of sliding contacts, two materials are required, i.e. one with a high hardness and the other with low shear strength. In case of composite coatings AHC+NL the matrix is a very hard and wear resistant anodic oxide coating (AHC whereas the solid lubricant used is the nanomaterial (NL featuring a low shear strength such as glassy carbon nanotubes (GC. Friction coefficient of cast iron GJL-350 sliding against the coating itself is much higher (0.18-0.22 than when it slides against a composite coating (0.08-0.14. It is possible to reduce the friction due to the presence of carbon nanotubes, or metal nanowires.

  6. Bioactive Glass-Ceramic Coatings Synthesized by the Liquid Precursor Plasma Spraying Process

    Science.gov (United States)

    Xiao, Yanfeng; Song, Lei; Liu, Xiaoguang; Huang, Yi; Huang, Tao; Chen, Jiyong; Wu, Yao; Wu, Fang

    2011-03-01

    In this study, the liquid precursor plasma spraying process was used to manufacture P2O5-Na2O-CaO-SiO2 bioactive glass-ceramic coatings (BGCCs), where sol and suspension were used as feedstocks for plasma spraying. The effect of precursor and spray parameters on the formation and crystallinity of BGCCs was systematically studied. The results indicated that coatings with higher crystallinity were obtained using the sol precursor, while nanostructured coatings predominantly consisting of amorphous phase were synthesized using the suspension precursor. For coatings manufactured from suspension, the fraction of the amorphous phase increased with the increase in plasma power and the decrease in liquid precursor feed rate. The coatings synthesized from the suspension plasma spray process also showed a good in vitro bioactivity, as suggested by the fast apatite formation when soaking into SBF.

  7. Finite element analysis on stresses field of normalized layer thickness within ceramic coating on aluminized steel

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Multilayer ceramic coatings were fabricated on steel substrate using a combined technique of hot dipping aluminum(HDA)and plasma electrolytic oxidation(PEO). A triangle of normalized layer thickness was created for describing thickness ratios of HDA/PEO coatings. Then, the effect of thickness ratio on stresses field of HDA/PEO coatings subjected to uniform normal contact load was investigated by finite element method. Results show that the surface tensile stress is mainly affected by the thickness ratio of Al layer when the total thickness of coating is unchanged. With the increase of Al layer thickness, the surface tensile stress rises quickly. When Al2O3 layer thickness increases, surface tensile stress is diminished. Meanwhile, the maximum shear stress moves rapidly towards internal part of HDA/PEO coatings. Shear stress at the Al2O3/Al interface is minimal when Al2O3 layer and Al layer have the same thickness.

  8. The evaluation of integrity and elasticity of thermally sprayed ceramic coatings by ultrasonics

    Energy Technology Data Exchange (ETDEWEB)

    Kauppinen, P. [VTT Manufacturing Technology, Espoo (Finland). Materials and Structural Integrity

    1997-12-31

    Thermally sprayed ceramic coatings are widely used in industrial applications where the coated component is subject to, e.g. high thermal loads or mechanical wear. The mechanical properties of the coating are finally created in the coating process and the chemical composition of the powder used as raw material can only give some hints about the properties of the final coating. Several non-destructive testing techniques are available for the detection of defects in ceramic materials or for the evaluation of density and density variations. In addition to this, ultrasonic techniques can be used for quantitative evaluation of elastic properties of materials. This evaluation is based on the measurement of sound velocities of different wave modes in the material and is normally applied only to relatively simple-shaped specimens having parallel surfaces. Acoustic microscopy operating at very high (> 100 MHz) frequencies has been used to measure the sound velocities in homogeneous and thin coatings. With this type of equipment, reliable and accurate results have been achieved in laboratory measurements. A lot of development work has been carried out world-wide to develop the measurement techniques and acoustic lenses (transducers) used in acoustic microscopy. However, less attention has been paid on the development of techniques for industrial applications on-site. The present work was focused on the development of measurement techniques for industrial applications. A new type of large-aperture low-frequency transducer was designed and constructed for the measurement of sound velocities in thermally sprayed ceramic coatings. The major difference to the lenses used in acoustic microscopy is that in the new transducer no separate lens is needed for focusing the sound beam. The piezoelectric element in the new transducer is a plastic (PVDF)-film that can be shaped to create the required focus. The practical measurement of the sound velocity is based on a modification of the V

  9. On the Anelastic Behavior of Plasma Sprayed Ceramic Coatings: Observations, Characterizations and Applications

    Science.gov (United States)

    Dwivedi, Gopal

    Plasma sprayed ceramic materials contain an assortment of microstructural defects, including pores, cracks, and interfaces arising from the droplet based assemblage of the spray deposition technique. The defective architecture of the deposits introduces a novel "anelastic" response in the coatings comprising of their non-linear and hysteretic stress-strain relationship under mechanical loading. It has been established that this anelasticity can be attributed to the relative movement of the embedded defects under varying stresses; while the non-linear response of the coatings arises from the opening/closure of defects, hysteresis is produced by the frictional sliding among defect surfaces. Recent studies have indicated that anelastic behavior of coatings can be a unique descriptor of their mechanical behavior and related to the defect configuration. In this dissertation, a multi-variable study employing systematic processing strategies was conducted to augment the understanding on various aspects of the reported anelastic behavior. Enhancements to bi-layer curvature measurement technique allowed for reliable and repeatable quantification of the anelastic response, enabling extraction of three anelastic parameters; elastic modulus, non-linear degree and hysteresis degree. This allowed for further exploration of the process space enabling controlled introduction of anelasticity in thermal sprayed ceramic coatings. This dissertation reports on these findings by first describing the experimental advancements in bilayer curvature measurements via thermal cycling of a coated beam. This experimental development allowed assessment of sensitivity and repeatability of the obtained anelastic parameters to varying microstructures imposed by processing excursions. Subsequently, controlled modification of anelasticity was achieved through material and process parameters as well as through extrinsic modification of the defects within the microstructure. The results suggest that

  10. Production of nano-ceramic coatings on titanium implants

    Science.gov (United States)

    Fomin, A. A.; Rodionov, I. V.; Fomina, M. A.; Petrova, N. V.

    2015-03-01

    Composite titania coatings modified with hydroxyapatite nanoparticles were obtained on intraosseous implants fabricated from commercially pure titanium and titanium alloy Ti-2.5Al-5Mo-5V. The present study aims to identify consistency changes of morphological characteristics and physico-mechanical properties of titanium items coatings obtained by oxidation during induction heat treatment and modification with colloidal hydroxyapatite nanoparticles. The influence of temperature between 600 and 1200 °C and duration of thermal modification from 1 to 300 s was studied. It was established that high hardness about 6.7±1.9 GPa for nanocrystalline TiO2 coatings and 19.2±0.6 GPa for nanoceramic "TiO2+HAp" coatings is reached at 1000 °C and 120 s.

  11. Texture in Metallic and Ceramic Films and Coatings

    OpenAIRE

    Czerwinski, F; J. A. Szpunar

    1999-01-01

    The properties of films and coatings can be optimized for a variety of applications by modifying their texture. Understanding how the texture in thin films is formed and how it can be controlled during film growth process is one of the most important areas of texture research. Several examples were selected to illustrate how the texture in films and coatings is developed and to explain how various properties of films are affected by texture. In particular, texture development during electrode...

  12. Innovative fiber coating systems based on organic modified ceramics

    Science.gov (United States)

    Schuster, Kay; Kobelke, Jens; Rose, Klaus; Helbig, Manfred; Zoheidi, Mohammad; Heinze, Alexander

    2010-02-01

    We describe the application of inorganic organic hybrid materials (ORMOCERs) as optical fiber coatings for use in Fiber Bragg Grating sensors and high power transmission fibers. The materials are UV curable, enable a single layer thickness of about 50 μm and show high a high peak temperature stability >300 °C. Regarding the fiber protection the coatings have been investigated using tensile strength measurements before and after temperature load. Best coatings maintain the high tensile strength of 68 N (125 μm fiber) with a Weibull parameter of 182 after a temperature cycling up to 300 °C. For the first time a low refractive index ORMOCER will be presented showing a numerical aperture of 0.47 at a wavelength of 1000 nm on a pure silica fiber. This corresponds to a refractive index of 1.37. The fiber possesses a fiber loss of 18 dB/km at a wavelength of 1000 nm. The fibers have been coated using a gravity as well as pressure technology. The latter possesses extremely minimized die equipment and is therefore well applicable for small coating amounts. The so called dead volume within the coating die is about 1 ml. The overall dead volume is only influenced by the supply pipe and can be reduced down to 5 ml.

  13. Residual Stress Analysis of Ceramic Thermal Barrier Coating Based on Thermal Spray Process

    Science.gov (United States)

    Arai, Masayuki; Wada, Eiji; Kishimoto, Kikuo

    Residual stress is generated in ceramic thermal barrier coatings (TBCs), which were sprayed by a plasma spray technology, due to the difference in coefficients of thermal expansion between the coating and the substrate. Previous experimental results obtained by the X-ray diffraction method indicated that the residual stress at the ceramic coating surface is tensile and could lead to TBC failure such as cracking and spalling of the ceramic coating. In this study, a numerical model that can predict the residual stress exactly is proposed by taking into account a thermal spray process. This numerical model is a layer-buildup model based on a shear-lag theory, and the residual stress contribution comes from two kinds of the following stress components: (1) quenching stress, which was generated in molten spray particles impinged onto the substrate, and (2) thermal stress, which was generated due to differences in thermal expansion between the deposited particle and the underlying substrate. It is shown herein that residual stress predicted by the proposed numerical model coincided with the experimental one obtained by the strain gage technique, with a good level of accuracy.

  14. Advanced Environmental Barrier Coating Development for SiC/SiC Ceramic Matrix Composites: NASA's Perspectives

    Science.gov (United States)

    Zhu, Dongming

    2016-01-01

    This presentation reviews NASA environmental barrier coating (EBC) system development programs and the coating materials evolutions for protecting the SiC/SiC Ceramic Matrix Composites in order to meet the next generation engine performance requirements. The presentation focuses on several generations of NASA EBC systems, EBC-CMC component system technologies for SiC/SiC ceramic matrix composite combustors and turbine airfoils, highlighting the temperature capability and durability improvements in simulated engine high heat flux, high pressure, high velocity, and with mechanical creep and fatigue loading conditions. The current EBC development emphasis is placed on advanced NASA 2700F candidate environmental barrier coating systems for SiC/SiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. Major technical barriers in developing environmental barrier coating systems, the coating integrations with next generation CMCs having the improved environmental stability, erosion-impact resistance, and long-term fatigue-environment system durability performance are described. The research and development opportunities for advanced turbine airfoil environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling are discussed.

  15. A new high temperature resistant glass–ceramic coating for gas turbine engine components

    Indian Academy of Sciences (India)

    Someswar Datta; Sumana Das

    2005-12-01

    A new high temperature and abrasion resistant glass–ceramic coating system (based on MgO–Al2O3–TiO2 and ZnO–Al2O3–SiO2 based glass systems) for gas turbine engine components has been developed. Thermal shock resistance, adherence at 90°-bend test and static oxidation resistance at the required working temperature (1000°C) for continuous service and abrasion resistance are evaluated using suitable standard methods. The coating materials and the resultant coatings are characterized using differential thermal analysis, differential thermogravimetric analysis, X-ray diffraction analysis, optical microscopy and scanning electron microscopy. The properties evaluated clearly showed the suitability of these coatings for protection of different hot zone components in different types of engines. XRD analysis of the coating materials and the resultant coatings showed presence of a number of microcrystalline phases. SEM micrographs indicate strong chemical bonding at the metal–ceramic interface. Optical micrographs showed smooth glossy impervious defect free surface finish.

  16. Electrochemical behavior of 45S5 bioactive ceramic coating on Ti6Al4V alloy for dental applications

    Science.gov (United States)

    Machado López, M. M.; Espitia Cabrera, M. I.; Faure, J.; Contreras García, M. E.

    2016-04-01

    Titanium and its alloys are widely used as implant materials because of their mechanical properties and non-toxic behavior. Unfortunately, they are not bioinert, which means that they can release ions and can only fix the bone by mechanical anchorage, this can lead to the encapsulation of dense fibrous tissue in the body. The bone fixation is required in clinical conditions treated by orthopedic and dental medicine. The proposal is to coat metallic implants with bioactive materials to establish good interfacial bonds between the metal substrate and bone by increasing bioactivity. Bioactive glasses, ceramics specifically 45 S5 Bioglass, have drawn attention as a serious functional biomaterial because osseointegration capacity. The EPD method of bioglass gel precursor was proposed in the present work as a new method to obtain 45S5/Ti6A14V for dental applications. The coatings, were thermally treated at 700 and 800°C and presented the 45 S5 bioglass characteristic phases showing morphology and uniformity with no defects, quantification percentages by EDS of Si, Ca, Na, P and O elements in the coating scratched powders, showed a good proportional relationship demonstrating the obtention of the 45S5 bioglass. The corrosion tests were carried out in Hank's solution. By Tafel extrapolation, Ti6Al4V alloy showed good corrosion resistance in Hank's solution media, by the formation of a passivation layer on the metal surface, however, in the system 45S5/Ti6Al4V there was an increase in the corrosion resistance; icon-, Ecorr and corrosion rate decreased, the mass loss and the rate of release of ions, were lower in this system than in the titanium alloy without coating.

  17. Hot Corrosion Behavior of Arc-Sprayed Highly Dense NiCr-Based Coatings in Chloride Salt Deposit

    Science.gov (United States)

    Qin, Enwei; Yin, Song; Ji, Hua; Huang, Qian; Liu, Zekun; Wu, Shuhui

    2017-03-01

    To make cities more environmentally friendly, combustible wastes tend to be incinerated in waste-to-energy power plant boilers. However, release of chlorine gas (Cl2) during incineration causes serious problems related to hot corrosion of boiler tubes and poses a safety threat for such plants. In this study, a pseudo-de Laval nozzle was employed in a twin-wire arc spray system to enhance the velocity of in-flight particles. Highly dense NiCr-based coatings were obtained using the modified nozzle gun. The coating morphology was characterized by optical microscopy and scanning electron microscopy, and hot corrosion testing was carried out in a synthetic molten chloride salt environment. Results showed that the dense NiCr-based coatings exhibited high resistance against corrosion by chlorine, which can be related to the typical splat lamellar microstructure and chemical composition as well as minor alloying elements such as Ti and Mo.

  18. Hot Corrosion Behavior of Arc-Sprayed Highly Dense NiCr-Based Coatings in Chloride Salt Deposit

    Science.gov (United States)

    Qin, Enwei; Yin, Song; Ji, Hua; Huang, Qian; Liu, Zekun; Wu, Shuhui

    2017-04-01

    To make cities more environmentally friendly, combustible wastes tend to be incinerated in waste-to-energy power plant boilers. However, release of chlorine gas (Cl2) during incineration causes serious problems related to hot corrosion of boiler tubes and poses a safety threat for such plants. In this study, a pseudo-de Laval nozzle was employed in a twin-wire arc spray system to enhance the velocity of in-flight particles. Highly dense NiCr-based coatings were obtained using the modified nozzle gun. The coating morphology was characterized by optical microscopy and scanning electron microscopy, and hot corrosion testing was carried out in a synthetic molten chloride salt environment. Results showed that the dense NiCr-based coatings exhibited high resistance against corrosion by chlorine, which can be related to the typical splat lamellar microstructure and chemical composition as well as minor alloying elements such as Ti and Mo.

  19. Additive manufacturing of Ti-Si-N ceramic coatings on titanium

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yanning; Sahasrabudhe, Himanshu; Bandyopadhyay, Amit, E-mail: amitband@wsu.edu

    2015-08-15

    Highlights: • 3D Printing or additive manufacturing of hard Ti-Si-N based ceramics coating on Ti metal substrate. • Understanding of phase transformation as a function of compositional variation. • Evaluation of influence of processing parameters and composition on wear resistance. - Abstract: In this study, Laser Engineered Net Shaping (LENS{sup TM}) was employed towards Additive Manufacturing/3D Printing of Ti-Si-N coatings with three different Ti-Si ratios on commercially pure titanium (cp-Ti) substrate. Microstructural analysis, phase analysis using X-ray diffraction, wear resistance and hardness measurements were done on LENS™ processed 3D printed coatings. Coatings showed graded microstructures and in situ formed phases. Results showed that microstructural variations and phase changes influence coating's hardness and wear resistance directly. High hardness values were obtained from all samples’ top surface where the hardness of coatings can be ranked as 90% Ti-10% Si-N coating (2093.67 ± 144 HV{sub 0.2}) > 100% Ti-N coating (1846 ± 68.5 HV{sub 0.2}) > 75% Ti-25% Si-N coating (1375.3 ± 61.4 HV{sub 0.2}). However, wear resistance was more dependent on inherent Si content, and samples with higher Si content showed better wear resistance.

  20. Post-treatment of Plasma-Sprayed Amorphous Ceramic Coatings by Spark Plasma Sintering

    Science.gov (United States)

    Chraska, T.; Pala, Z.; Mušálek, R.; Medřický, J.; Vilémová, M.

    2015-04-01

    Alumina-zirconia ceramic material has been plasma sprayed using a water-stabilized plasma torch to produce free standing coatings. The as-sprayed coatings have very low porosity and are mostly amorphous. The amorphous material crystallizes at temperatures above 900 °C. A spark plasma sintering apparatus has been used to heat the as-sprayed samples to temperatures above 900 °C to induce crystallization, while at the same time, a uniaxial pressure of 80 MPa has been applied to their surface. After such post-treatment, the ceramic samples are crystalline and have very low open porosity. The post-treated material exhibits high hardness and significantly increased flexural strength. The post-treated samples have a microstructure that is best described as nanocomposite with the very small crystallites embedded in an amorphous matrix.

  1. Development of wear-resistant ceramic coatings for diesel engine components. Volume 1, Coating development and tribological testing: Final report: DOE/ORNL Ceramic Technology Project

    Energy Technology Data Exchange (ETDEWEB)

    Naylor, M.G.S. [Cummins Engine Co., Inc., Columbus, IN (United States)

    1992-06-01

    The tribological properties of a variety of advanced coating materials have been evaluated under conditions which simulate the piston ring -- cylinder liner environment near top ring reversal in a heavy duty diesel engine. Coated ``ring`` samples were tested against a conventional pearlitic grey cast iron liner material using a high temperature reciprocating wear test rig. Tests were run with a fresh CE/SF 15W40lubricant at 200 and 350{degrees}C, with a high-soot, engine-tested oil at 200{degrees}C and with no lubrication at 200{degrees}C. For lowest wear under boundary lubricated conditions, the most promising candidates to emerge from this study were high velocity oxy-fuel (HVOF) Cr{sub 3} C{sub 2} - 20% NiCr and WC - 12% Co cermets, low temperature arc vapor deposited (LTAVD) CrN and plasma sprayed chromium oxides. Also,plasma sprayed Cr{sub 2}O{sub 3} and A1{sub 2}O{sub 3}-ZrO{sub 2} materials were found to give excellent wear resistance in unlubricated tests and at extremely high temperatures (450{degrees}C) with a syntheticoil. All of these materials would offer substantial wear reductions compared to the conventional electroplated hard chromium ring facing and thermally sprayed metallic coatings, especially at high temperatures and with high-soot oils subjected to degradation in diesel environments. The LTAVD CrN coating provided the lowest lubricated wear rates of all the materials evaluated, but may be too thin (4 {mu}m) for use as a top ring facing. Most of the coatings evaluated showed higher wear rates with high-soot, engine-tested oil than with fresh oil, with increases of more than a factor of ten in some cases. Generally, metallic materials were found to be much more sensitive to soot/oil degradation than ceramic and cermet coatings. Thus, decreased ``soot sensitivity`` is a significant driving force for utilizing ceramic or cermet coatings in diesel engine wear applications.

  2. Adhesion of E. coli to silver- or copper-coated porous clay ceramic surfaces

    Science.gov (United States)

    Yakub, I.; Soboyejo, W. O.

    2012-06-01

    Porous ceramic water filters (CWFs), produced by sintering a mixture of clay and a combustible material (such as woodchips), are often used in point-of-use water filtration systems that occlude microbes by size exclusion. They are also coated with colloidal silver, which serves as a microbial disinfectant. However, the adhesion of microbes to porous clay surfaces and colloidal silver coated clay surfaces has not been studied. This paper presents the results of atomic force microscopy (AFM) measurements of the adhesion force between Escherichia coli bacteria, colloidal silver, and porous clay-based ceramic surfaces. The adhesion of silver and copper nanoparticles is also studied in control experiments on these alternative disinfectant materials. The adhesive force between the wide range of possible bi-materials was measured using pull-off measurements during force microscopy. These were combined with measurements of AFM tip radii/substrate roughness that were incorporated into adhesion models to obtain the adhesion energies for the pair wise interaction. Of the three antimicrobial metals studied, the colloidal silver had the highest affinity for porous ceramic surface (125 ± 32 nN and ˜0.29 J/m2) while the silver nanoparticles had the highest affinity for E. coli bacteria (133 ± 21 nN and ˜0.39 J/m2). The implications of the results are then discussed for the design of ceramic water filter that can purify water by adsorption and size exclusion.

  3. Glass-(nAg, nCu) Biocide Coatings on Ceramic Oxide Substrates

    Science.gov (United States)

    Esteban-Tejeda, Leticia; Malpartida, Francisco; Díaz, Luis Antonio; Torrecillas, Ramón; Rojo, Fernando; Moya, José Serafín

    2012-01-01

    The present work was focused on obtaining biocide coatings constituted by a glassy soda-lime matrix containing silver or copper nanoparticles on ceramic (alumina and zirconia based) substrates. Both glassy coatings showed a high biocide activity against Gram−, Gram+ bacteria and yeast, reducing cell numbers more than three logarithms. Silver nanoparticles had a significantly higher biocide activity than copper nanoparticles, since the lixiviation levels required to reduce cell numbers more than 3 logarithms was of almost 1–2 µg/cm2 in the case of silver nanoparticles, and 10–15 µg/cm2 for the copper nanoparticles. PMID:22427967

  4. Glass-(nAg, nCu biocide coatings on ceramic oxide substrates.

    Directory of Open Access Journals (Sweden)

    Leticia Esteban-Tejeda

    Full Text Available The present work was focused on obtaining biocide coatings constituted by a glassy soda-lime matrix containing silver or copper nanoparticles on ceramic (alumina and zirconia based substrates. Both glassy coatings showed a high biocide activity against Gram-, Gram+ bacteria and yeast, reducing cell numbers more than three logarithms. Silver nanoparticles had a significantly higher biocide activity than copper nanoparticles, since the lixiviation levels required to reduce cell numbers more than 3 logarithms was of almost 1-2 µg/cm(2 in the case of silver nanoparticles, and 10-15 µg/cm(2 for the copper nanoparticles.

  5. Corrosion protection of SiC-based ceramics with CVD mullite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Sarin, V.; Mulpuri, R.; Auger, M. [Boston University, Boston, MA (United States) Manufacturing Engineering

    1996-04-20

    SiC based ceramics have been identified as the leading candidate materials for elevated temperature applications in harsh oxidation/corrosion environments. It has been established that a protective coating can be effectively used to avoid problems with excessive oxidation and hot corrosion. However, to date, no coating configuration has been developed that can withstand the rigorous requirements imposed by such applications. Chemical vapor deposited (CVD) mullite coatings due to their desirable properties of toughness, corrosion resistance, and good coefficient of thermal expansion match with SiC are being developed as a potential solution. Formation of mullite on ceramic substrates via chemical vapor deposition was investigated. Thermodynamic calculations performed on the AlCl{sub 3}- SiCl{sub 4}-CO{sub 2}-H{sub 2} system were used to construct equilibrium CVD phase diagrams. Through process optimization, crystalline CVD mullite coatings have been successfully grown on SiC and Si{sub 3}N{sub 4} substrates. Results from the thermodynamic analysis, process optimization, and effect of various process parameters on deposition rate and coating morphology are discussed.

  6. Preliminary Investigation of Ceramic-Coated Anodes for Cathodic Protection.

    Science.gov (United States)

    1983-08-01

    used Electrodes," Journal De Physique, Vol 4. p CI (1977) R. Itai and anodes that are either inexpensive and very large, or H. Kunai, U.S. Patent No...have been made to manu- protection system anodes was only begun recently. facture anodes coated with magnetite. Itai and Kanai Two types of systems

  7. Study of the influence of ceramic thermal coating on the aircraft blade vibration

    Directory of Open Access Journals (Sweden)

    Daniel Dragomir-Stanciu

    2014-05-01

    Full Text Available The paper analyzes the influence of the ceramic layer on the vibration of the high pressure stage turbine blades in take-off transient conditions. As reference model, the high pressure stage blades of the Tumanski R13 jet engine were considered. The analyse was done using the Ansys 14.5. The vibration eigenmodes and eigenvalues for the blade with and without a ZrO2/3%Y2O3 deposited coating are compared.

  8. Synergistic effect between nano-ceramic lubricating additives and electroless deposited Ni-W-P coating

    Science.gov (United States)

    Chen, Min; Cheng, Wushan; Zhao, Zuxin; Huang, Xiaobo

    2013-01-01

    The major solving ways for the material wear are surface modification and lubrication. Currently, the researches at home and abroad are all limited to the single study of either nano-lubricating oil additive or electroless deposited coating. The surface coating has high hardness and high wear resistance, however, the friction reduction performance of the coating with high hardness is not good, the thickness of the coating is limited, and the coating can not regenerate after wearing. The nano-lubricating additives have good tribological performance and self-repair function, but under heavy load, the self-repair rate to the worn surface with the nano-additives is smaller than the wearing rate of the friction pair. To solve the above problems, the Ni-W-P alloy coating and deposition process with excellent anti-wear, and suitable for industrial application were developed, the optimum bath composition and process can be obtained by studying the influence of the bath composition, temperature and PH value to the deposition rate and the plating solution stability. The tribological properties as well as anti-wear and friction reduction mechanism of wear self-repair nano-ceramic lubricating additives are also studied. The ring-block abrasion testing machine and energy dispersive spectrometer are used to explore the internal relation between the coating and the nano-lubricating oil additives, and the tribology mechanism, to seek the synergetic effect between the two. The test results show that the wear resistance of Ni-W-P alloy coating (with heat treatment and in oil with nano-ceramic additives) has increased hundreds times than 45 steel as the metal substrate in basic oil, the friction reduction performance is improved. This research breaks through the bottleneck of previous separate research of the above-mentioned two methods, and explores the combination use of the two methods in industrial field.

  9. Obtaining of ceramics biphasic dense and porous; Obtencao de ceramicas bifasicas densas e porosas

    Energy Technology Data Exchange (ETDEWEB)

    Pallone, E.M.J.A.; Rigo, E.C.S., E-mail: eliria@usp.b [Universidade de Sao Paulo (FZEA/USP), Pirassununga, SP (Brazil). Dept. de Ciencias Basicas; Silva, K.L. [Universidade Estadual de Campinas (FEM/UNICAMP), SP (Brazil). Faculdade de Engenharia Mecanica; Rezende, M.E. [Universidade Sao Francisco, Itatiba, SP (Brazil); Fraga, A.F. [Universidade Federal de Sao Carlos (DEMa/UFSCar), SP (Brazil). Dept. de Engenharia de Materiais; Marques, R.F.C. [Universidade Federal de Alfenas (UNIFAL), Pocos de Caldas, MG (Brazil)

    2010-07-01

    Among the bioceramic hydroxyapatite (HAP) and beta-tricalcium phosphate (beta-TCP) are materials commonly used in biomedical field. Their combined properties result in a material with absorbable and at the same time with bioactive surface. Called biphasic ceramics such materials respond more quickly when exposed to physiological environment. In this work, powders of HAP/beta-TCP were obtained by chemical precipitation. After obtaining the post-phase was added at a ratio of 0, 15% and 30w% aqueous solutions of corn starch in order to obtain porous bodies. After mixing the resulting solutions were dried, resigned in tablet form and sintered at 1300 deg C. The initial powder was characterized by X-ray diffraction with Rietveld refinement to quantify the phases present. Bodies-of-evidence has been characterized by calculating the bulk density, X-ray diffraction (XRD), scanning electron microscopy and diametral compression. (author)

  10. Evaluation of nano ceramic coating on radiographic defects of thin-walled AL4-4 aluminum alloy sand casting

    Directory of Open Access Journals (Sweden)

    Mansour Borouni

    2016-10-01

    Full Text Available Internal defects are among the problems in gravity casting of aluminum parts. The main internal volumetric defects are gas and shrinkage defects which form during solidification of the melt and drastically reduce the quality of the produced parts. These defects adversely affect the mechanical properties of thin walled castings parts. In this study, ceramic nanoparticles coatings were applied on the sand mold and the effect of mold coatings on the reduction of defects were investigated. X-ray radiography was used to detect defects in sand molds with ceramic nanoparticles coatings. For comparison, this test was performed on molds with micro-ceramic and graffiti coatings and uncoated sand mold. The results showed that the maximum amount of gas and shrinkage defects was observed in casting parts from AL4-1 alloy in uncoated molds. On the other hand, the minimum defects were found in molds coated with ceramic nanoparticles. It seems that the reduced defects in casting parts in molds coated with ceramic nanoparticles may be due to high thermal and chemical stability and higher heat transfer rate of the coating. These results can facilitate the production of high quality aluminum alloys parts using nanotechnology.

  11. Property Evaluation and Damage Evolution of Environmental Barrier Coatings and Environmental Barrier Coated SiC/SiC Ceramic Matrix Composite Sub-Elements

    Science.gov (United States)

    Zhu, Dongming; Halbig, Michael; Jaskowiak, Martha; Hurst, Janet; Bhatt, Ram; Fox, Dennis S.

    2014-01-01

    This paper describes recent development of environmental barrier coatings on SiC/SiC ceramic matrix composites. The creep and fatigue behavior at aggressive long-term high temperature conditions have been evaluated and highlighted. Thermal conductivity and high thermal gradient cyclic durability of environmental barrier coatings have been evaluated. The damage accumulation and complex stress-strain behavior environmental barrier coatings on SiCSiC ceramic matrix composite turbine airfoil subelements during the thermal cyclic and fatigue testing of have been also reported.

  12. METAL-CERAMIC INTERFACES IN LASER COATED ALUMINUM-ALLOYS

    NARCIS (Netherlands)

    ZHOU, XB; DEHOSSON, JTM

    1994-01-01

    A novel process was developed to firmly coat an aluminium alloy, Al6061, with alpha-Al2O3 by means of laser processing. In this approach a mixture of SiO2 and Al powder was used to inject in the laser melted surface of aluminium. A reaction product alpha-Al2O3 layer of a thickness of 100 mum was cre

  13. Metal-Ceramic Interfaces in Laser Coated Aluminium Alloys

    NARCIS (Netherlands)

    Zhou, X.B.; Hosson, J.Th.M. De

    1994-01-01

    A novel process was developed to firmly coat an aluminium alloy, Al6061, with α-Al2O3 by means of laser processing. In this approach a mixture of SiO2 and Al powder was used to inject in the laser melted surface of aluminium. A reaction product α-Al2O3 layer of a thickness of 100 µm was created whic

  14. Raman microscopic studies of PVD deposited hard ceramic coatings

    CERN Document Server

    Constable, C P

    2000-01-01

    GPa were deposited onto SS and HSS substrates. Subsequent Raman measurements found a correlation coefficient of 0.996 between Raman band position and stress (determined via XRD methods). In addition, there was also a similar correlation coefficient observed between hardness and Raman shift (cm sup - sup 1). The application of mechanical stresses on a TiAICrN coating via a stress rig was investigated and tensile and compressive shifts were observed. stresses caused by the scratching process. These shifts were found to be the largest at the edges of scratches. The Raman mapping of 'droplets', a defect inherent to PVD deposition processes, found that higher compressive stresses and large amounts of disorder occurred for coating growth onto droplets. Strategies designed to evaluate the ability of Raman microscopy to monitor the extent of real wear on cutting tools were evaluated. The removal of a coating layer and subsequent detection of a base layer proved successful. This was then expanded to real wear situatio...

  15. Porous biphasic calcium phosphate ceramics coated with nano-hydroxyapatite and seeded with mesenchymal stem cells for reconstruction of radius segmental defects in rabbits.

    Science.gov (United States)

    Hu, Jianzhong; Yang, Zhiming; Zhou, Yongchun; Liu, Yong; Li, Kaiyang; Lu, Hongbin

    2015-11-01

    The osteoconduction of porous biphasic calcium phosphate (BCP) ceramics has been widely reported. In a previous study, we demonstrated that applying a nano-hydroxyapatite (nHA) coating enhances the osteoinductive potential of BCP ceramics, making these scaffolds more suitable for bone tissue engineering applications. The aim of the present study was to determine the effects of reconstructing radius defects in rabbits using nHA-coated BCP ceramics seeded with mesenchymal stem cells (MSCs) and to compare the bone regeneration induced by different scaffolds. Radius defects were created in 20 New Zealand rabbits, which were divided into four groups by treatment: porous BCP ceramics (Group A), nHA-coated porous BCP ceramics (Group B), porous BCP ceramics seeded with rabbit MSCs (Group C), and nHA-coated porous BCP ceramics seeded with rabbit MSCs (Group D). After in vitro incubation, the cell/scaffold complexes were implanted into the defects. Twelve weeks after implantation, the specimens were examined macroscopically and histologically. Both the nHA coating and seeding with MSCs enhanced the formation of new bone tissue in the BCP ceramics, though the osteoinductive potential of the scaffolds with MSCs was greater than that of the nHA-coated scaffolds. Notably, the combination of nHA coating and MSCs significantly improved the bone regeneration capability of the BCP ceramics. Thus, MSCs seeded into porous BCP ceramics coated with nHA may be an effective bone substitute to reconstruct bone defects in the clinic.

  16. Ceramic coatings on diesel engine components. Period covered: January 1979-August 1979

    Energy Technology Data Exchange (ETDEWEB)

    Kvernes, I; Lillerud, K P

    1979-10-01

    Diesel engines with imporved thermal efficiency and fuel economy or flexibility will be required to meet automotive energy conservation goals. These goals can be met by minimizing engine heat loss to the coolant, i.e., by the use of a thermal insulating barrier on the interior surfaces of the combustion space. The development and testing of ceramic coatings for diesel engine components are discussed. These coatings include oxides of Al, Cr, Zr, Mg, Si, Ti, and Ca, and Mo and Ch carbides. Data on their application and thermodynamic and wear characteristics are presented. It was concluded that, although the spraying processes used have not been optimized, plasma-spray technology has made it possible to coat diesel engine parts with ceramic materials. Preliminary results show that, relative to valves and piston crowns: stabilized ZrO/sub 2/ coating under certain conditions increases the working life of various components; higher combustion temperature may improve the thermal efficiency by increased turbocharger air delivery; reduction in the component temperatures decreases the thermal stresses; the ZrO/sub 2/.MgO shows improved corrosion resistance in combustion gases compared to ZrO/sub 2/.Y/sub 2/O/sub 3/ and ZrO/sub 2/.CaO; the limitations of the coatings have to be defined in more detail; and the adherence of thicker coatings has to be improved. Optimization of the spraying process with respect to particle fusion is necessary. Also, Mo and Ch carbide coatings were found to increase the service life of piston rings. (LCL)

  17. Physical and Electromagnetic Properties of Customized Coatings for SNS Injection Ceramic Chambers and Extraction Ferrite Kickers

    CERN Document Server

    Hseuh Hsiao Chaun; He, Ping; Henderson, Stuart; Pai, Chien; Raparia, Deepak; Todd, Robert J; Wang, Lanfa; Wei, Jie; Weiss, Daniel; Yung Lee, Yong

    2005-01-01

    The inner surfaces of the 248 m SNS accumulator ring vacuum chambers are coated with ~100 nm of titanium nitride (TiN) to reduce the secondary electron yield (SEY) of the chamber walls. All the ring inner surfaces are made of stainless or inconel, except those of the injection and extraction kickers. Ceramic vacuum chambers are used for the 8 injection kickers to avoid shielding of a fast-changing kicker field and to reduce eddy current heating. The internal diameter was coated with Cu to reduce the beam coupling impedance and provide passage for beam image current, and a TiN overlayer to reduce SEY. The ferrite surfaces of the 14 extraction kicker modules were coated with TiN to reduce SEY. Customized masks were used to produce coating strips of 1 cm x 5 cm with 1 to 1.5 mm separation among the strips. The masks maximized the coated area to more than 80%, while minimizing the eddy current effect to the kicker rise time. The coating method, as well as the physical and electromagnetic properties of the coating...

  18. Bioactive ceramic coating on orthopedic implants for enhanced bone tissue integration

    Science.gov (United States)

    Aniket

    Tissue integration between bone and orthopedic implant is essential for implant fixation and longevity. An immunological response leads to fibrous encapsulation of metallic implants leading to implant instability and failure. Bioactive ceramics have the ability to directly bond to bone; however, they have limited mechanical strength for load bearing applications. Coating bioactive ceramics on metallic implant offers the exciting opportunity to enhance bone formation without compromising the mechanical strength of the implant. In the present study, we have developed a novel bioactive silica-calcium phosphate nanocomposite (SCPC) coating on medical grade Ti-6Al-4V orthopedic implant using electrophoretic deposition (EPD) and evaluated bone tissue response to the coated implant at the cellular level. The effect of SCPC composition and suspending medium pH on the zeta potential of three different SCPC formulations; SCPC25, SCPC50 and SCPC75 were analyzed. The average zeta potential of SCPC50 in pure ethanol was more negative than that of SCPC25 or SCPC75; however the difference was not statistically significant. Ti-6Al-4V discs were passivated, coated with SCPC50 (200 nm - 10 mum) and thermally treated at 600 - 800 ºC to produce a coating thickness in the range of 43.1 +/- 5.7 to 30.1 +/- 4.6 μm. After treatment at 600, 700 and 800 ºC, the adhesion strength at the SCPC50/Ti-6Al-4V interface was 42.6 +/- 3.6, 44.7 +/- 8.7 and 47.2 +/- 4.3 MPa, respectively. XRD analyses of SCPC50 before and after EPD coating indicated no change in the crystallinity of the material. Fracture surface analyses showed that failure occurred within the ceramic layer or at the ceramic/polymer interface; however, the ceramic/metal interface was intact in all samples. The adhesion strength of SCPC50-coated substrates after immersion in PBS for 2 days (11.7 +/- 3.9 MPa) was higher than that measured on commercially available hydroxyapatite (HA) coated substrates (5.5 +/- 2.7 MPa), although the

  19. Compound Ceramic Coatings Grown by Micro-plasma Oxidation on Ti-6Al-4V Alloy

    Institute of Scientific and Technical Information of China (English)

    XUE Wei; YAO Zhong-ping; JIANG Zhao-hua

    2006-01-01

    Compound ceramics coatings on the Ti-6Al-4V alloy were prepared by the direct current micro-plasma oxidation (MPO) in NaAlO2 solution. The composition and morphology of the coatings were studied with the X-ray diffraction (XRD) and the scanning electron microscopy (SEM), respectively. Inductively coupled plasma atomic emission spectrometer technique was used to analyze the solution features of Ti-6Al-4V alloy in the process of preparation. The results reveal that Al2TiO5 forms in the coatings at the initial stages of MPO reaction, and its content changes rapidly with the reaction continuing: after 20 min, the ceramics coatings are composed of α-Al2O3, γ-Al2O3 and Al2TiO5, but after 40 min, its main composition is of α-Al2O3. The content of Ti in the solution will increase when the MPO time extends, and as will Al in the anode area until, after 30 min, it reaches the maximum and keeps constant from then on. Both substrata of Ti and Al in the electrolyte join the MPO reaction at the initial stage, where the formation of Al2TiO5 happens; but as the MPO reaction prolongs, more and more Al in the electrolyte will take part in the reaction, leading to the appearance of a large amount of Al2O3.

  20. In situ formation of low friction ceramic coatings on carbon steel by plasma electrolytic oxidation in two types of electrolytes

    Science.gov (United States)

    Wang, Yunlong; Jiang, Zhaohua

    2009-04-01

    In situ formation of ceramic coatings on Q235 carbon steel was achieved by plasma electrolytic oxidation (PEO) in carbonate electrolyte and silicate electrolyte, respectively. The surface and cross-section morphology, phase and elemental composition of PEO coatings were examined by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS). The bond strength of the coating was determined using a direct pull-off test. The hardness as well as tribological properties of the ceramic coating was primarily studied. The results indicated that the coating obtained in carbonate electrolyte was Fe 3O 4, while the coating achieved from silicate electrolyte was proved to be amorphous. Both kinds of coatings showed coarse and porous surface. The Fe 3O 4 coatings obtained in carbonate electrolyte showed a high bonding strength to the substrate up to 20 ± 2 MPa and the value was 15 ± 2 MPa for the amorphous coatings obtained in carbonate electrolyte. The micro hardness of the amorphous coating and the Fe 3O 4 coating was 1001 Hv and 1413 Hv, respectively, which was more than two and three times as that of the Q235 alloy substrate (415 Hv). The friction coefficient exhibited by amorphous coating and Fe 3O 4 coating was 0.13 and 0.11, respectively, both lower than the uncoated Q235 substrate which ranged from 0.17 to 0.35.

  1. Microstructure and Corrosion Resistance of Cr7C3/γ-Fe Ceramal Composite Coating Fabricated by Plasma Cladding

    Institute of Scientific and Technical Information of China (English)

    LIU Junbo

    2007-01-01

    A new type in situ Cr7C3/γ-Fe ceramal composite coating was fabricated on substrate of hardened and tempered grade C steel by plasma cladding with Fe-Cr-C alloy powders. The ceramal composite coating has a rapidly solidified microstructure consisting of primary Cr7C3 and the Cr7C3/γ-Fe eutectics, and is metallurgically bonded to the degree C steel substrate. The corrosion resistances of the coating in water solutions of 0.5 mol/L H2SO4 and 3.5% NaCl were evaluated utilizing the electrochemical polarization corrosion-test method. Because of the inherent excellent corrosion-resisting properties of the constituting phase and the rapidly solidified homogeneous microstructure, the plasma clad ceramal composite coating exhibits excellent corrosion resistance in the water solutions of 0.5 mol/L H2SO4 and 3.5% NaCl.

  2. Development of wear resistant ceramic coatings for diesel engine components

    Energy Technology Data Exchange (ETDEWEB)

    Haselkorn, M.H. (Caterpillar, Inc., Peoria, IL (United States))

    1992-04-01

    Improved fuel economy and a reduction of emissions can be achieved by insulation of the combustion chamber components to reduce heat rejection. However, insulating the combustion chamber components will also increase the operating temperature of the piston ring/cylinder liner interface from approximately 150{degree}C to over 300{degree}C. Existing ring/liner materials can not withstand these higher operating temperatures and for this reason, new materials need to be developed for this critical tribological interface. The overall goal of this program is the development of piston ring/cylinder liner material pairs which would be able to provide the required friction and wear properties at these more severe operating conditions. More specifically, this program first selected, and then evaluated, potential d/wear resistant coatings which could be applied to either piston rings an or cylinder liners and provide, at 350{degree}C under lubricated conditions, coefficients of friction below 0.1 and wear rates of less than 25 {times} lO{sup {minus}6} mm/hour. The processes selected for applying the candidate wear resistant coatings to piston rings and/or cylinder liners were plasma spraying, chemical vapor, physical vapor and low temperature arc vapor deposition techniques as well as enameling techniques.

  3. Phase Stability and Thermal Conductivity of Composite Environmental Barrier Coatings on SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Benkel, Samantha; Zhu, Dongming

    2011-01-01

    Advanced environmental barrier coatings are being developed to protect SiC/SiC ceramic matrix composites in harsh combustion environments. The current coating development emphasis has been placed on the significantly improved cyclic durability and combustion environment stability in high-heat-flux and high velocity gas turbine engine environments. Environmental barrier coating systems based on hafnia (HfO2) and ytterbium silicate, HfO2-Si nano-composite bond coat systems have been processed and their stability and thermal conductivity behavior have been evaluated in simulated turbine environments. The incorporation of Silicon Carbide Nanotubes (SiCNT) into high stability (HfO2) and/or HfO2-silicon composite bond coats, along with ZrO2, HfO2 and rare earth silicate composite top coat systems, showed promise as excellent environmental barriers to protect the SiC/SiC ceramic matrix composites.

  4. Environmental/Thermal Barrier Coatings for Ceramic Matrix Composites: Thermal Tradeoff Studies

    Science.gov (United States)

    Murthy, Pappu L. M.; Brewer, David; Shah, Ashwin R.

    2007-01-01

    Recent interest in environmental/thermal barrier coatings (EBC/TBCs) has prompted research to develop life-prediction methodologies for the coating systems of advanced high-temperature ceramic matrix composites (CMCs). Heat-transfer analysis of EBC/TBCs for CMCs is an essential part of the effort. It helps establish the resulting thermal profile through the thickness of the CMC that is protected by the EBC/TBC system. This report documents the results of a one-dimensional analysis of an advanced high-temperature CMC system protected with an EBC/TBC system. The one-dimensional analysis was used for tradeoff studies involving parametric variation of the conductivity; the thickness of the EBC/TBCs, bond coat, and CMC substrate; and the cooling requirements. The insight gained from the results will be used to configure a viable EBC/TBC system for CMC liners that meet the desired hot surface, cold surface, and substrate temperature requirements.

  5. Strength degradation and failure limits of dense and porous ceramic membrane materials

    DEFF Research Database (Denmark)

    Pećanac, G.; Foghmoes, Søren Preben Vagn; Lipińska-Chwałek, M.;

    2013-01-01

    Thin dense membrane layers, mechanically supported by porous substrates, are considered as the most efficient designs for oxygen supply units used in Oxy-fuel processes and membrane reactors. Based on the favorable permeation properties and chemical stability, several materials were suggested...... as promising membrane and substrate materials: Ba0.5Sr0.5Co0.8Fe0.2O3−δ, La0.6−xSr0.4Co0.2Fe0.8O3−δ (x=0, 0.02) and Ce0.9Gd0.1O1.95−δ. Although membranes operate at elevated temperatures, the ends of tubes in certain three-end concepts remain almost at room temperature. The current work concentrates...... on the failure potential of these membrane parts, where in a complex device also the highest residual stresses should arise due to differences in thermal expansion. In particular, sensitivity of the materials to subcritical crack growth was assessed since the long-term reliability of the component does not only...

  6. Severe wear behaviour of alumina balls sliding against diamond ceramic coatings

    Indian Academy of Sciences (India)

    ANURADHA JANA; NANDADULAL DANDAPAT; MITUN DAS; VAMSI KRISHNA BALLA; SHIRSHENDU CHAKRABORTY; RAJNARAYAN SAHA; AWADESH KUMAR MALLIK

    2016-04-01

    At present alumina is themost widely used bio-ceramic material for implants.However, diamond surface offers very good solid lubricant for different machinery, equipment including biomedical implants (hip implants, knee implants, etc.), since the coefficient of friction (COF) of diamond is lower than alumina. In this tribological study, alumina ball was chosen as the counter body material to show better performance of the polycrystalline diamond (PCD) coatings in biomedical load-bearing applications.Wear and friction data were recorded for microwave plasma chemical vapour deposition (MWCVD) grown PCD coatings of four different types, out of which two sampleswere as-deposited coatings, one was chemo-mechanically polished and the other diamond sample was made free standing by wet-chemical etching of the silicon wafer. The coefficient of friction of the MWCVD grown PCD against Al$_2$O$_3$ ball under dry ambient condition was found in the range of 0.29–0.7, but in the presence of simulated body fluid, the COF reduces significantly, in the range of 0.03–0.36. The samples were then characterized by Raman spectroscopy for their quality, by coherence scanning profilometer for surface roughness and by electron microscopy for their microstructural properties. Alumina balls worn out ($14.2 \\times 10^{−1}$ mm$^3$) very rapidly with zero wear for diamond ceramic coatings. Since the generation of wear particle is the main problem for load-bearing prosthetic joints, it was concluded that the PCD material can potentially replace existing alumina bio-ceramic for their bettertribological properties.

  7. Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

    Institute of Scientific and Technical Information of China (English)

    GAO Yu-zhou; ZHANG Hui-chen; WANG Liang; YAN Li

    2004-01-01

    TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure.

  8. Thermal Conductivity and Water Vapor Stability of Ceramic HfO2-Based Coating Materials

    Science.gov (United States)

    Zhu, Dong-Ming; Fox, Dennis S.; Bansal, Narottam P.; Miller, Robert A.

    2004-01-01

    HfO2-Y2O3 and La2Zr2O7 are candidate thermal/environmental barrier coating materials for gas turbine ceramic matrix composite (CMC) combustor liner applications because of their relatively low thermal conductivity and high temperature capability. In this paper, thermal conductivity and high temperature phase stability of plasma-sprayed coatings and/or hot-pressed HfO2-5mol%Y2O3, HfO2-15mol%Y2O3 and La2Zr2O7 were evaluated at temperatures up to 1700 C using a steady-state laser heat-flux technique. Sintering behavior of the plasma-sprayed coatings was determined by monitoring the thermal conductivity increases during a 20-hour test period at various temperatures. Durability and failure mechanisms of the HfO2-Y2O3 and La2Zr2O7 coatings on mullite/SiC Hexoloy or CMC substrates were investigated at 1650 C under thermal gradient cyclic conditions. Coating design and testing issues for the 1650 C thermal/environmental barrier coating applications will also be discussed.

  9. 纳米陶瓷涂层的性能及应用%Properties and Applications of Nanostructured Ceramic Coatings

    Institute of Scientific and Technical Information of China (English)

    武创; 郗雨林; 王其红; 王国阳

    2011-01-01

    纳米陶瓷涂层与微米级陶瓷涂层相比,晶粒更细化且分散均匀,晶界数量大幅度增加,其在硬度、韧性、耐磨性、结合强度、抗蚀性、致密度等方面有显著的提高,已在航空航天、船舶、化工等工业领域得到应用.本文针对纳米陶瓷涂层的性能及应用给予介绍.%Due to the considerable decrease in grain size of nanostructured ceramic coatings, the grains disperse more uniformly, and the number of grain boundary also increase significantly. As a result, the properties of nanostructured ceramic coatings,including hardness, toughness, wear resistance, bonding strength, corrosion resistance and density may be improved obviously as compared with microstructured ceramic coatings. The nanostructured ceramic coatings have thus been widely used in many fields such as aerospace, shipbuilding, chemical industries and so on. This paper will introduce the properties and application of nanostructured ceramic coating in detail.

  10. Characterization of Ceramic Composite-Membranes Prepared by ORMOSIL Coating Sol

    Institute of Scientific and Technical Information of China (English)

    Goo-Dae Kim; Tae-Bong Kim

    2004-01-01

    Sol-gel methods offer many advantages over conventional slip-casting, including the ability to produce ceramic membranes. They are purer, more homogeneous, more reactive and contain a wider variety of compositions. We produced ormosil sol using sol-gel process under different molecular weight of polymer species [polyethylene glycol (PEG) ] in total system [Tetraethyl ortho silicate(TEOS)-polyethylene glycol (PEG)]. The properties of as-prepared ormosil sol such as,viscosity, gelation time were characterized. Also, the ceramic membrane was prepared by dip-coating with synthetic sol and its micro-structure was observed by scanning electron microscopy. The permeability and rejection efficiency of membrane for oil/water emulsion were evaluated as cross-flow apparatus. The ormosil sol coated Membrane is easily formed by steric effect of polymer and it improves flux efficiency because infiltration into porous support decreased. Its flux efficiency is elevated about 200(1/m2·h) compared with colloidal sol coated membrane at point of five minutes from starting test.

  11. Preparation of α-Al2O3 base ceramic coating on aluminum alloy via thermo-decomposition of diaspore

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The aim of this work is to describe the possibilities of preparing a corundum coating onaluminum alloy through in-situ chemical reaction at a relative low temperature. The transformationconditions of diaspore (β-AIOOH) to corundum (α-Al2O3 ) are studied using X-ray diffraction analy-sis. Temperature and heating time are two main factors influencing the transformation. Suitableheating parameters can lower the transformation temperature. On this basis, a new process isdeveloped to produce corundum ceramic coating on an aluminum alloy substrate. The phasecomposition and microstructure of the coating are studied using X-ray diffraction analysis andScanning Electron Microscopy. Abrasion properties of the coating are evaluated by ring-block tri-botester. The results show that it is feasible to obtain ceramic coatings on aluminum alloy sub-strates by means of thermo-decomposition of diaspore.

  12. Microstructure and Cavitation Erosion Properties of Ceramic Coatings Fabricated on Ti-6Al-4V Alloy by Pack Carburizing

    Science.gov (United States)

    Li, Haibin; Cui, Zhenduo; Li, Zhaoyang; Zhu, Shengli; Yang, Xianjin

    2014-08-01

    In this study, Ti-6Al-4V alloy was processed by pack carburizing to improve the cavitation erosion behavior. X-ray diffraction and scanning-electron microscopy (SEM) analysis showed that a uniform and crack-free ceramic coating formed on the surface of the treated samples. The coating layer comprised primary TiC and less oxide. Cavitation erosion experiment results indicated that the treated samples have the factor of 3.44 to 6.68 increase in cavitation erosion resistance ( R e) as compared with the as-received sample. The ceramic coatings with high hardness and good metallurgical bonding were responsible for the enhanced cavitation erosion properties. When the coatings were treated at condition of high temperature and/or long time, the R e was enervated due to the thin oxide film formed at the outermost surface. Cavitation erosion mechanism for the coatings was characterized as brittle mode by SEM observation of the worn surfaces.

  13. Spectral Emittance of Uncoated and Ceramic-Coated Inconel and Type 321 Stainless Steel

    Science.gov (United States)

    Richmond, Joseph C.; Stewart, James E.

    1959-01-01

    The normal spectral emittance of Inconel and type 321 stainless steel with different surface treatments was measured at temperatures of 900, 1,200, 1,500, and 1,800 F over a wavelength range of 1.5 to 15 microns. The measurements involved comparison of the radiant energy emitted by the heated specimen with that emitted by a comparison standard at the same temperature by means of a recording double-beam infrared spectrophotometer. The silicon carbide comparison standard had previously been calibrated against a laboratory black-body furnace. Surface treatments included electropolishing, sandblasting, electro-polishing followed by oxidation in air for 1/2 hour at 1,800 F, sandblasting followed by oxidation in air for 1/2 hour at 1,800 F, application of National Bureau of Standards coating A-418, and application of NBS ceramic coating N-143. The normal spectral emittance of both alloys in the electropolished condition was low and decreased very slightly with increasing wavelength while in the sandblasted condition it was somewhat higher and did not vary appreciably with wavelength. The oxidation treatment greatly increased the normal spectral emittance of both the electropolished and sandblasted type 321 stainless steel specimens and of the electropolished Inconel specimens and introduced some spectral selectivity into the curves. The oxidation increased the normal spectral emittance of the sandblasted Inconel specimens only moderately. Of the specimens to which a coating about 0.002 inch thick was applied, those coated with A-418 had higher emittance at all wavelengths than did those coated with N-143, and the coated specimens of Inconel had higher spectral emittance at all wavelengths than did the corresponding specimens of type 321 stainless steel. Both coatings were found to be partially transparent to the emitted energy at this thickness but essentially opaque at a thickness of 0.005 inch. Coated specimens with 0.005 inch or more of coating did not show the effect

  14. Synergistic thermal stabilization of ceramic/co-polyimide coated polypropylene separators for lithium-ion batteries

    Science.gov (United States)

    Lee, Yunju; Lee, Hoogil; Lee, Taejoo; Ryou, Myung-Hyun; Lee, Yong Min

    2015-10-01

    To improve the safety of lithium-ion batteries (LIBs), co-polyimide (PI) P84 was introduced as a polymeric binder for Al2O3/polymer composite surface coatings on polypropylene (PP) separators. By monitoring the dimensional shrinkage of the PP separators at high temperatures, we verified a synergistic thermal stabilization effect between the Al2O3 ceramic and the PI polymeric binder. Although PI was thermally stable up to 300 °C, a coating consisting solely of PI did not impede the PP separator dimensional changes (-22% at 150 °C). On the other hand, the Al2O3/PI-coated PP separators efficiently impeded the thermal shrinkage (-10% at 150 °C). In contrast, an Al2O3/poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) combination lowered the thermal stability of the PP separators (-33% at 150 °C). As a result, the Al2O3/PI-coated PP separators remarkably suppressed the internal short-circuit of the unit half-cells associated with separator thermal shrinkage (100 min at 160 °C), whereas the PVdF-HFP retained only 40 min under identical conditions. The Al2O3/PI-coated PP separators achieved rate capabilities and cell performances similar to those of the bare PP separators.

  15. 3D Analysis of Porosity in a Ceramic Coating Using X-ray Microscopy

    Science.gov (United States)

    Klement, Uta; Ekberg, Johanna; Kelly, Stephen T.

    2017-02-01

    Suspension plasma spraying (SPS) is a new, innovative plasma spray technique using a feedstock consisting of fine powder particles suspended in a liquid. Using SPS, ceramic coatings with columnar microstructures have been produced which are used as topcoats in thermal barrier coatings. The microstructure contains a wide pore size range consisting of inter-columnar spacings, micro-pores and nano-pores. Hence, determination of total porosity and pore size distribution is a challenge. Here, x-ray microscopy (XRM) has been applied for describing the complex pore space of the coatings because of its capability to image the (local) porosity within the coating in 3D at a resolution down to 50 nm. The possibility to quantitatively segment the analyzed volume allows analysis of both open and closed porosity. For an yttria-stabilized zirconia coating with feathery microstructure, both open and closed porosity were determined and it could be revealed that 11% of the pore volumes (1.4% of the total volume) are closed pores. The analyzed volume was reconstructed to illustrate the distribution of open and closed pores in 3D. Moreover, pore widths and pore volumes were determined. The results on the complex pore space obtained by XRM are discussed in connection with other porosimetry techniques.

  16. Nanostructured Multilayer Composite Coatings on Ceramic Cutting Tools for Finishing Treatment of High-Hardness Quenched Steels

    Science.gov (United States)

    Vereshchaka, A. A.; Batako, A. D.; Sotova, E. S.; Vereshchaka, A. S.

    2016-01-01

    The functional role of nanostructured multilayer composite coatings (NMCC) deposited on the operating surfaces of replaceable faceted cutting inserts (CI) from cutting ceramics based on aluminum oxides with additives of titanium carbides is studied. It is shown that the developed NMCC not only raise substantially the endurance of the ceramic tools under high-speed dry treatment of quenched steels but also improve the quality and accuracy of processing of the parts and the ecological parameters of the cutting process.

  17. Nuclear Rocket Ceramic Metal Fuel Fabrication Using Tungsten Powder Coating and Spark Plasma Sintering

    Science.gov (United States)

    Barnes, M. W.; Tucker, D. S.; Hone, L.; Cook, S.

    2017-01-01

    Nuclear thermal propulsion is an enabling technology for crewed Mars missions. An investigation was conducted to evaluate spark plasma sintering (SPS) as a method to produce tungsten-depleted uranium dioxide (W-dUO2) fuel material when employing fuel particles that were tungsten powder coated. Ceramic metal fuel wafers were produced from a blend of W-60vol% dUO2 powder that was sintered via SPS. The maximum sintering temperatures were varied from 1,600 to 1,850 C while applying a 50-MPa axial load. Wafers exhibited high density (>95% of theoretical) and a uniform microstructure (fuel particles uniformly dispersed throughout tungsten matrix).

  18. High temperature resistant cermet and ceramic compositions. [for thermal resistant insulators and refractory coatings

    Science.gov (United States)

    Phillips, W. M. (Inventor)

    1978-01-01

    High temperature oxidation resistance, high hardness and high abrasion and wear resistance are properties of cermet compositions particularly to provide high temperature resistant refractory coatings on metal substrates, for use as electrical insulation seals for thermionic converters. The compositions comprise a sintered body of particles of a high temperature resistant metal or metal alloy, preferably molybdenum or tungsten particles, dispersed in and bonded to a solid solution formed of aluminum oxide and silicon nitride, and particularly a ternary solid solution formed of a mixture of aluminum oxide, silicon nitride and aluminum nitride. Ceramic compositions comprising a sintered solid solution of aluminum oxide, silicon nitride and aluminum nitride are also described.

  19. Static tensile and tensile creep testing of four boron nitride coated ceramic fibers at elevated temperatures

    Science.gov (United States)

    Coguill, Scott L.; Adams, Donald F.; Zimmerman, Richard S.

    1989-01-01

    Six types of uncoated ceramic fibers were static tensile and tensile creep tested at various elevated temperatures. Three types of boron nitride coated fibers were also tested. Room temperature static tensile tests were initially performed on all fibers, at gage lengths of 1, 2, and 4 inches, to determine the magnitude of end effects from the gripping system used. Tests at one elevated temperature, at gage lengths of 8 and 10 inches, were also conducted, to determine end effects at elevated temperatures. Fiber cross sectional shapes and areas were determined using scanning electron microscopy. Creep testing was typically performed for 4 hours, in an air atmosphere.

  20. Multilayer (TiN, TiAlN) ceramic coatings for nuclear fuel cladding

    Energy Technology Data Exchange (ETDEWEB)

    Alat, Ece, E-mail: exa179@psu.edu [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Motta, Arthur T. [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Comstock, Robert J.; Partezana, Jonna M. [Westinghouse Electric Co., Beulah Rd, Pittsburgh, PA 1332 (United States); Wolfe, Douglas E. [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Applied Research Laboratory, The Pennsylvania State University, 119 Materials Research Building, University Park, PA 16802 (United States)

    2016-09-15

    In an attempt to develop an accident-tolerant fuel (ATF) that can delay the deleterious consequences of loss-of-coolant-accidents (LOCA), multilayer coatings were deposited onto ZIRLO{sup ®} coupon substrates by cathodic arc physical vapor deposition (CA-PVD). Coatings were composed of alternating TiN (top) and Ti{sub 1-x}Al{sub x}N (2-layer, 4-layer, 8-layer and 16-layer) layers. The minimum TiN top coating thickness and coating architecture were optimized for good corrosion and oxidation resistance. Corrosion tests were performed in static pure water at 360 °C and 18.7 MPa for up to 90 days. The optimized coatings showed no spallation/delamination and had a maximum of 6 mg/dm{sup 2} weight gain, which is 6 times smaller than that of a control sample of uncoated ZIRLO{sup ®} which showed a weight gain of 40.2 mg/dm{sup 2}. The optimized architecture features a ∼1 μm TiN top layer to prevent boehmite phase formation during corrosion and a TiN/TiAlN 8-layer architecture which provides the best corrosion performance. - Highlights: • The first study on multilayer TiAlN and TiN ceramic coatings on ZIRLO{sup ®} coupons. • Corrosion tests were performed at 360°C and 18.7 MPa for up to 90 days. • Coatings adhered well to the substrate, and showed no spallation/delamination. • Weight gains were six times lower than those of uncoated ZIRLO{sup ®} samples. • Longer and higher temperature corrosion tests will be discussed in a further paper.

  1. Characterization on C/SiC Ceramic Matrix Composites with Novel Fiber Coatings

    Science.gov (United States)

    Petko, Jeanne; Kiser, J. Douglas; McCue, Terry; Verrilli, Michael

    2002-01-01

    Ceramic Matrix Composites (CMCs) are attractive candidate materials in the aerospace industry due to their high specific strength, low density and higher temperature capabilities. The National Aeronautics and Space Administration (NASA) is pursuing the use of CMC components in advanced Reusable Launch Vehicle (RLV) propulsion applications. Carbon fiber-reinforced silicon carbide (C/SiC) is the primary material of interest for a variety of RLV propulsion applications. These composites offer high- strength carbon fibers and a high modulus, oxidation-resistant matrix. For comparison, two types of carbon fibers were processed with novel types of interface coatings (multilayer and pseudoporous). For RLV propulsion applications, environmental durability will be critical. The coatings show promise of protecting the carbon fibers from the oxidizing environment. The strengths and microstructures of these composite materials are presented.

  2. A New Testing Method to Evaluate Adhesion Strength of Ceramic Top Coat in TBCs

    Science.gov (United States)

    Okazaki, Masakazu; Yamagishi, Satoshi; Osakabe, Masakazu; Fukanuma, Hirotaka

    A new testing method to evaluate adhesion strength of ceramic top coat has been proposed, employing a ring shape of TBC specimen specifically designed. It was shown by the experiments that a delamination behavior of the top coat was successfully reproduced in the proposed method, associating with a buckling mode; a similar mode frequently observed in actual gas turbine components. A method to quantitatively evaluate a resistance to delamination was also introduced, based on an energy release rate criterion. The experiments demonstrated that the testing method provided reasonable adhesion strength in terms of energy criterion, that almost agreed with the values measured by other researchers employing different type of testing method. It was also shown that the present method has many advantages, compared with the traditional methods.

  3. Pulsed-terahertz reflectometry for health monitoring of ceramic thermal barrier coatings.

    Science.gov (United States)

    Chen, Chia-Chu; Lee, Dong-Joon; Pollock, Tresa; Whitaker, John F

    2010-02-15

    Terahertz time-domain reflectometry was used to monitor the progress of a thermally grown oxide layer and stress-induced, air-filled voids at the interface of an Yttria-stabilized-zirconia ceramic thermal-barrier coating and a metal surface. The thicknesses of these internal layers, observed in scanning-electron-microscope images to increase with thermal-exposure time, have been resolved - even when changing on the order of only a few micrometers - by distinguishing not only increased delays in the arrival times of terahertz pulses reflected from this multilayer structure, but also changes in the width and shape of the pulses. These unique features can be used to predict the lifetime of thermal-barrier coatings and to indicate or warn of spallation conditions. The trends of the experimental results are also confirmed through Fresnel-reflection time-domain simulations.

  4. Microstructure and low–temperature relaxor behavior of dense K{sub 2}Nb{sub 4}O{sub 11} ceramics derived from sol–gel route

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lina; Hou, Yudong, E-mail: ydhou@bjut.edu.cn; Zheng, Mupeng; Zhu, Mankang; Yan, Hui

    2015-01-15

    High purity tetragonal tungsten-bronze type K{sub 2}Nb{sub 4}O{sub 11} fine powders were synthesized via an economical sol–gel route and the crystal structure was solved by Rietveld refinement of X–ray powder diffraction. Structural evolution during calcination was found to occur via translation of the edge shared octahedra into a corner sharing coordination. Using nano-structured powder as precursor, dense K{sub 2}Nb{sub 4}O{sub 11} ceramics were successfully fabricated by pressure-less sintering. This maiden achievement allowed for primary dielectric characterization of this ceramic compound. The quantitative analysis based on empirical parameters, ΔT{sub m} and γ, reveals a relaxor nature in the temperature region below 200 K. More remarkably, the dielectric constant and loss are almost frequency independent in the wide range of 1 Hz–1 MHz at room temperature and a high dielectric constant and low loss (ε{sub r} = 200 and tan δ = 0.007) makes them good materials for dielectric components for embedded capacitors and multilayer ceramic capacitors. - Highlights: • Pure K{sub 2}Nb{sub 4}O{sub 11} fine powders were synthesized via an economical sol-gel route. • Dense K{sub 2}Nb{sub 4}O{sub 11} ceramics were fabricated by conventional sintering methods. • Relaxor behavior of K{sub 2}Nb{sub 4}O{sub 11} ceramics exists at low temperature around 160 K.

  5. The energy efficiency and environmental impacts in the ceramic industry: the case of ceramic coatings segment; A eficiencia energetica e os impactos na industria ceramica: o caso do segmento de revestimentos ceramicos

    Energy Technology Data Exchange (ETDEWEB)

    Berni, Mauro Donizeti [Universidade Estadual de Campinas (NIPE/UNICAMP), SP (Brazil). Nucleo Interdisciplinar de Planejamento Energetico], email: mauro_berni@yahoo.com.br; Bajay, Sergio Valdir [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Fac. de Engenharia Mecanica. Dept. de Energia

    2010-07-01

    The Brazilian ceramic industry has great importance for the country, with a stake of more than 1.0% of GDP, or approximately $ 6 billion. The segment of ceramic coatings due to the higher revenues, production, employment, value of manufacturing and penetration in foreign markets, has been the highlight of the ceramic sector. Besides most representative in economic terms, the ceramic coatings segment presents with the largest final energy consumption and volume of emissions. This work shows the evolution of the final energy consumption of the ceramic sector, showing that the segment of ceramic coatings can be successful harnessing of potential energy conservation with reflections on the mitigation of greenhouse gas emissions. Therefore, the study evaluates: the process and energy sources; reducing impacts along the entire life cycle of products and the management actions providing a new corporate culture and social and environmental responsibility.

  6. Development of wear-resistant ceramic coatings for diesel engine components

    Energy Technology Data Exchange (ETDEWEB)

    Naylor, M.G.S. (Cummins Engine Co., Inc., Columbus, IN (United States))

    1992-06-01

    The tribological properties of a variety of advanced coating materials have been evaluated under conditions which simulate the piston ring -- cylinder liner environment near top ring reversal in a heavy duty diesel engine. Coated ring'' samples were tested against a conventional pearlitic grey cast iron liner material using a high temperature reciprocating wear test rig. Tests were run with a fresh CE/SF 15W40lubricant at 200 and 350{degrees}C, with a high-soot, engine-tested oil at 200{degrees}C and with no lubrication at 200{degrees}C. For lowest wear under boundary lubricated conditions, the most promising candidates to emerge from this study were high velocity oxy-fuel (HVOF) Cr{sub 3} C{sub 2} - 20% NiCr and WC - 12% Co cermets, low temperature arc vapor deposited (LTAVD) CrN and plasma sprayed chromium oxides. Also,plasma sprayed Cr{sub 2}O{sub 3} and A1{sub 2}O{sub 3}-ZrO{sub 2} materials were found to give excellent wear resistance in unlubricated tests and at extremely high temperatures (450{degrees}C) with a syntheticoil. All of these materials would offer substantial wear reductions compared to the conventional electroplated hard chromium ring facing and thermally sprayed metallic coatings, especially at high temperatures and with high-soot oils subjected to degradation in diesel environments. The LTAVD CrN coating provided the lowest lubricated wear rates of all the materials evaluated, but may be too thin (4 {mu}m) for use as a top ring facing. Most of the coatings evaluated showed higher wear rates with high-soot, engine-tested oil than with fresh oil, with increases of more than a factor of ten in some cases. Generally, metallic materials were found to be much more sensitive to soot/oil degradation than ceramic and cermet coatings. Thus, decreased soot sensitivity'' is a significant driving force for utilizing ceramic or cermet coatings in diesel engine wear applications.

  7. Microstructure and mechanical properties of plasma sprayed Al2O3 – 13%TiO2 Ceramic Coating

    Directory of Open Access Journals (Sweden)

    Wahab Juyana A

    2017-01-01

    Full Text Available This paper focused on the effect of deposition conditions on the microstructural and mechanical properties of the ceramic coating. In this study, Al2O3 – 13%TiO2 coated mild steel were prepared by using atmospheric plasma spray technology with different plasma power ranging from 25 kW to 40 kW. The as-sprayed coatings consist of γ-Al2O3 phase as the major phase and small amount of the titania phase existed in the coating structure. High degree of fully melted region was observed in the surface morphology for the coating sprayed with high plasma power, which lead to the high hardness and low percentage of porosity. In this study, nanoindentation test was carried out to investigate mechanical properties of the coating and the results showed that the coatings possess high elastic behaviour, which beneficial in engineering practice.

  8. Studies on a diesel engine with ceramic coating of the combustion chamber

    Energy Technology Data Exchange (ETDEWEB)

    Jaskolski, J.

    1985-06-01

    Two piston alloys were developed which were combined with ceramic fibres made of aluminium silicone oxide. These alloys have proved to be wear resistant and resistant to thermal stresses. A simulation stand was used to study the influence of these cylinder head coatings, which are applied by plasma spraying, on the thermal status of the piston, and the influence of the thermic insulation of the sections of the combustion chamber was studied on an engine test stand. The ceramic coating was 0.2 mm thick; the temperature drops in the fire land and in the piston ring groove were 40 K and 20 K respectively. The thermically insulated piston head meant that the combustion of the mixture took less time, altered the fuel consumption, raised the exhaust temperature and reduced exhaust toxicity and the amount of air sucked in. The heat given off with the coolant was reduced by 5 to 15%. The overall finding was that raising the temperature and hence the exhaust energy creates favourable conditions for the application of turbo-charging, thereby improving overall performance.

  9. Interfacial Bonding Strength of TiN Film Coated on Si3N4 Ceramic Substrate

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The fraction of TiN/Si3N4 in the cross section was observed with scanning electric microscope (SEM), and residual stresses of TiN coated on the surface of Si3N4 ceramic were measured with X-ray diffraction (XRD).The hardness of TiN film was measured, and bonding strength of TiN film coated on Si3N4 substrate was measured by scratching method. The formed mechanism of residual stress and the failure mechanism of the bonding interface in the film were analyzed, and the adhesion mechanism of TiN film was investigated preliminarily. The results show that residual stresses of TiN film are all behaved as compressive stress, and TiN film is represented smoothly with brittle fracture, which is closely bonded with Si3N4 substrate. TiN film has high hardness and bonding strength of about 500 MPa, which could satisfy usage requests of the surface of cutting Si3N4 ceramic.

  10. Preparation and antimicrobial assay of ceramic brackets coated with TiO2 thin films

    Science.gov (United States)

    Cao, Shuai; Wang, Ye; Cao, Lin; Wang, Yu; Lin, Bingpeng; Lan, Wei

    2016-01-01

    Objective Different methods have been utilized to prevent enamel demineralization and other complications during orthodontic treatment. However, none of these methods can offer long-lasting and effective prevention of orthodontic complications or interventions after complications occur. Considering the photocatalytic effect of TiO2 on organic compounds, we hoped to synthesize a novel bracket with a TiO2 thin film to develop a photocatalytic antimicrobial effect. Methods The sol-gel dip coating method was used to prepare TiO2 thin films on ceramic bracket surfaces. Twenty groups of samples were composed according to the experimental parameters. Crystalline structure and surface morphology were characterized by X-ray diffraction and scanning electron microscopy, respectively; film thickness was examined with a surface ellipsometer. The photocatalytic properties under ultraviolet (UV) light irradiation were analyzed by evaluating the degradation ratio of methylene blue (MB) at a certain time. Antibacterial activities of selected thin films were also tested against Lactobacillus acidophilus and Candida albicans. Results Films with 5 coating layers annealed at 700℃ showed the greatest photocatalytic activity in terms of MB decomposition under UV light irradiation. TiO2 thin films with 5 coating layers annealed at 700℃ exhibited the greatest antimicrobial activity under UV-A light irradiation. Conclusions These results provide promising guidance in prevention of demineralization by increasing antimicrobial activities of film coated brackets. PMID:27226960

  11. Residual stress evaluation in the vicinity of ceramic coating interface using polychromatic X-ray method

    Energy Technology Data Exchange (ETDEWEB)

    Shibano, Jun-ichi; Ukai, Takayoshi; Tadano, Shigeru [Hokkaido Univ., Sapporo (Japan). Faculty of Engineering; Todoh, Masahiro

    1995-06-01

    This paper presents a polychromatic X-ray method for nondestructive evaluation of residual stress distributed in the vicinity of the interface between a ceramic coating layer and a substrate metal. Since the strain is assumed to be a linear function of the depth, the strain distribution along the depth direction can be obtained from the weighted mean strain equation calculated by considering the intensity of diffracted X-rays over the penetration depth. Therefore, the distribution along the depth direction of the residual stress was determined by the strain distributions in two directions: the vertical direction and the inclined direction to the surface. SUS316 coated with TiN by the PVD process was used as the specimen. The residual stress distributions in the coating layer and the substrate of the specimen were evaluated using this method. As a result, not only compressive residual stress in the coating layer but also the stress gradient in the substrate could be confirmed simultaneously and nondestructively. (author).

  12. Silver ion doped ceramic nano-powder coated nails prevent infection in open fractures: In vivo study.

    Science.gov (United States)

    Kose, Nusret; Çaylak, Remzi; Pekşen, Ceren; Kiremitçi, Abdurrahman; Burukoglu, Dilek; Koparal, Savaş; Doğan, Aydın

    2016-02-01

    Despite improvement in operative techniques and antibiotic therapy, septic complications still occur in open fractures. We developed silver ion containing ceramic nano powder for implant coating to provide not only biocompatibility but also antibacterial activity to the orthopaedic implants. We hypothesised silver ion doped calcium phosphate based ceramic nano-powder coated titanium nails may prevents bacterial colonisation and infection in open fractures as compared with uncoated nails. 33 rabbits divided into three groups. In the first group uncoated, in the second group hydroxyapatite coated, and in the third group silver doped hydroxyapatite coated titanium nails were inserted left femurs of animals from knee regions with retrograde fashion. Before implantation of nails 50 μl solution containing 10(6)CFU/ml methicillin resistance Staphylococcus aureus (MRSA) injected intramedullary canal. Rabbits were monitored for 10 weeks. Blood was taken from rabbits before surgery and on 2nd, 6th and 10th weeks. Blood was analysed for biochemical parameters, blood count, C-reactive protein and silver levels. At the end of the 10 weeks animals were sacrificed and rods were extracted in a sterile fashion. Swab cultures were taken from intramedullary canal. Bacteria on titanium rods were counted. Liver, heart, spleen, kidney and central nervous tissues samples were taken for determining silver levels. Histopathological evaluation of bone surrounding implants was also performed. No significant difference was detected between the groups from hematologic, biochemical, and toxicological aspect. Microbiological results showed that less bacterial growth was detected with the use of silver doped ceramic coated implants compared to the other two groups (p=0.003). Accumulation of silver was not detected. No cellular inflammation was observed around the silver coated prostheses. No toxic effect of silver on bone cells was seen. Silver ion doped calcium phosphate based ceramic nano

  13. Acoustic emission analysis of Vickers indentation fracture of cermet and ceramic coatings

    Science.gov (United States)

    Faisal, N. H.; Ahmed, R.

    2011-12-01

    The aim of this work was to develop an instrumented experimental methodology of quantitative material evaluation based on the acoustic emission (AE) monitoring of a dead-weight Vickers indentation. This was to assess the degree of cracking and hence the toughness of thermally sprayed coatings. AE data were acquired during indentation tests on samples of coatings of nominal thickness 250-325 µm at a variety of indentation loads ranging from 49 to 490 N. Measurements were carried out on five different carbide and ceramic coatings (HVOF as-sprayed WC-12%Co (JP5000 and JetKote), HIPed WC-12%Co (JetKote) and as-sprayed Al2O3 (APS/Metco and HVOF/theta-gun)). The raw AE signals recorded during indentation were analysed and the total surface crack length around the indent determined. The results showed that the total surface crack length measured gave fracture toughness (K1c) values which were consistent with the published literature for similar coatings but evaluated using the classical approach (Palmqvist/half-penny model). Hence, the total surface crack length criteria can be applied to ceramic and cermet coatings which may or may not exhibit fracture via radial cracks. The values of K1c measured were 3.4 ± 0.1 MPa m1/2 for high-velocity oxygen fuel (HVOF) (theta-gun) Al2O3, 4.6 ± 0.3 MPa m1/2 for as-sprayed HVOF (JetKote) WC-12%Co, 7.1±0.1 MPa m1/2 for as-sprayed HVOF (JP5000) WC-12%Co and 7.4 ± 0.2 MPa m1/2 for HIPed HVOF (JetKote) WC-12%Co coatings. The crack lengths were then calibrated against the AE response and correlation coefficients evaluated. The values of K1c measured using AE correlations were 3.3 MPa m1/2 for HVOF (theta-gun) Al2O3, 2.6 MPa m1/2 for APS (Metco) Al2O3, 2.5 MPa m1/2 for as-sprayed HVOF (JetKote) WC-12%Co, 6.3 MPa m1/2 for as-sprayed HVOF (JP5000) WC-12%Co and 8.6 MPa m1/2 for HIPed HVOF (JetKote) WC-12%Co coatings. It is concluded that within each category of coating type, AE can be used as a suitable surrogate for crack length

  14. In Vitro and In Vivo Evaluation of Zinc-Modified Ca–Si-Based Ceramic Coating for Bone Implants

    Science.gov (United States)

    Zheng, Xuebin; He, Dannong; Ye, Xiaojian; Wang, Meiyan

    2013-01-01

    The host response to calcium silicate ceramic coatings is not always favorable because of their high dissolution rates, leading to high pH within the surrounding physiological environment. Recently, a zinc-incorporated calcium silicate-based ceramic Ca2ZnSi2O7 coating, developed on a Ti-6Al-4V substrate using plasma-spray technology, was found to exhibit improved chemical stability and biocompatibility. This study aimed to investigate and compare the in vitro response of osteoblastic MC3T3-E1 cells cultured on Ca2ZnSi2O7 coating, CaSiO3 coating, and uncoated Ti-6Al-4V titanium control at cellular and molecular level. Our results showed Ca2ZnSi2O7 coating enhanced MC3T3-E1 cell attachment, proliferation, and differentiation compared to CaSiO3 coating and control. In addition, Ca2ZnSi2O7 coating increased mRNA levels of osteoblast-related genes (alkaline phosphatase, procollagen α1(I), osteocalcin), insulin-like growth factor-I (IGF-I), and transforming growth factor-β1 (TGF-β1). The in vivo osteoconductive properties of Ca2ZnSi2O7 coating, compared to CaSiO3 coating and control, was investigated using a rabbit femur defect model. Histological and histomorphometrical analysis demonstrated new bone formation in direct contact with the Ca2ZnSi2O7 coating surface in absence of fibrous tissue and higher bone-implant contact rate (BIC) in the Ca2ZnSi2O7 coating group, indicating better biocompatibility and faster osseointegration than CaSiO3 coated and control implants. These results indicate Ca2ZnSi2O7 coated implants have applications in bone tissue regeneration, since they are biocompatible and able to osseointegrate with host bone. PMID:23483914

  15. In vitro and in vivo evaluation of zinc-modified ca-si-based ceramic coating for bone implants.

    Science.gov (United States)

    Yu, Jiangming; Li, Kai; Zheng, Xuebin; He, Dannong; Ye, Xiaojian; Wang, Meiyan

    2013-01-01

    The host response to calcium silicate ceramic coatings is not always favorable because of their high dissolution rates, leading to high pH within the surrounding physiological environment. Recently, a zinc-incorporated calcium silicate-based ceramic Ca2ZnSi2O7 coating, developed on a Ti-6Al-4V substrate using plasma-spray technology, was found to exhibit improved chemical stability and biocompatibility. This study aimed to investigate and compare the in vitro response of osteoblastic MC3T3-E1 cells cultured on Ca2ZnSi2O7 coating, CaSiO3 coating, and uncoated Ti-6Al-4V titanium control at cellular and molecular level. Our results showed Ca2ZnSi2O7 coating enhanced MC3T3-E1 cell attachment, proliferation, and differentiation compared to CaSiO3 coating and control. In addition, Ca2ZnSi2O7 coating increased mRNA levels of osteoblast-related genes (alkaline phosphatase, procollagen α1(I), osteocalcin), insulin-like growth factor-I (IGF-I), and transforming growth factor-β1 (TGF-β1). The in vivo osteoconductive properties of Ca2ZnSi2O7 coating, compared to CaSiO3 coating and control, was investigated using a rabbit femur defect model. Histological and histomorphometrical analysis demonstrated new bone formation in direct contact with the Ca2ZnSi2O7 coating surface in absence of fibrous tissue and higher bone-implant contact rate (BIC) in the Ca2ZnSi2O7 coating group, indicating better biocompatibility and faster osseointegration than CaSiO3 coated and control implants. These results indicate Ca2ZnSi2O7 coated implants have applications in bone tissue regeneration, since they are biocompatible and able to osseointegrate with host bone.

  16. Thermal Conductivity of Advanced Ceramic Thermal Barrier Coatings Determined by a Steady-state Laser Heat-flux Approach

    Science.gov (United States)

    Zhu, Dong-Ming; Miller, Robert A.

    2004-01-01

    The development of low conductivity and high temperature capable thermal barrier coatings requires advanced testing techniques that can accurately and effectively evaluate coating thermal conductivity under future high-performance and low-emission engine heat-flux conditions. In this paper, a unique steady-state CO2 laser (wavelength 10.6 microns) heat-flux approach is described for determining the thermal conductivity and conductivity deduced cyclic durability of ceramic thermal and environmental barrier coating systems at very high temperatures (up to 1700 C) under large thermal gradients. The thermal conductivity behavior of advanced thermal and environmental barrier coatings for metallic and Si-based ceramic matrix composite (CMC) component applications has also been investigated using the laser conductivity approach. The relationships between the lattice and radiation conductivities as a function of heat flux and thermal gradient at high temperatures have been examined for the ceramic coating systems. The steady-state laser heat-flux conductivity approach has been demonstrated as a viable means for the development and life prediction of advanced thermal barrier coatings for future turbine engine applications.

  17. Cooling of gas turbines IX : cooling effects from use of ceramic coatings on water-cooled turbine blades

    Science.gov (United States)

    Brown, W Byron; Livingood, John N B

    1948-01-01

    The hottest part of a turbine blade is likely to be the trailing portion. When the blades are cooled and when water is used as the coolant, the cooling passages are placed as close as possible to the trailing edge in order to cool this portion. In some cases, however, the trailing portion of the blade is so narrow, for aerodynamic reasons, that water passages cannot be located very near the trailing edge. Because ceramic coatings offer the possibility of protection for the trailing part of such narrow blades, a theoretical study has been made of the cooling effect of a ceramic coating on: (1) the blade-metal temperature when the gas temperature is unchanged, and (2) the gas temperature when the metal temperature is unchanged. Comparison is also made between the changes in the blade or gas temperatures produced by ceramic coatings and the changes produced by moving the cooling passages nearer the trailing edge. This comparison was made to provide a standard for evaluating the gains obtainable with ceramic coatings as compared to those obtainable by constructing the turbine blade in such a manner that water passages could be located very near the trailing edge.

  18. Corrosion resistant coatings for SiC and Si{sub 3}N{sub 4} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen Thierry; Shaokai Yang; J.J. Brown

    1998-09-01

    It is the goal of this program to (1) develop coatings for SiC and Si{sub 3}N{sub 4} that will enhance their performance as heat exchangers under coal combustion conditions and (2) to conduct an in-depth evaluation of the cause and severity of ceramic heat exchanger deterioration and failure under coal combustion conditions.

  19. Creep Behavior of Hafnia and Ytterbium Silicate Environmental Barrier Coating Systems on SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Fox, Dennis S.; Ghosn, Louis J.; Harder, Bryan

    2011-01-01

    Environmental barrier coatings will play a crucial role in future advanced gas turbine engines because of their ability to significantly extend the temperature capability and stability of SiC/SiC ceramic matrix composite (CMC) engine components, thus improving the engine performance. In order to develop high performance, robust coating systems for engine components, appropriate test approaches simulating operating temperature gradient and stress environments for evaluating the critical coating properties must be established. In this paper, thermal gradient mechanical testing approaches for evaluating creep and fatigue behavior of environmental barrier coated SiC/SiC CMC systems will be described. The creep and fatigue behavior of Hafnia and ytterbium silicate environmental barrier coatings on SiC/SiC CMC systems will be reported in simulated environmental exposure conditions. The coating failure mechanisms will also be discussed under the heat flux and stress conditions.

  20. Interfacial coatings for ceramic-matrix composites -- Volume 2. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Sambasivan, S.

    1998-06-09

    This report summarizes the task conducted to examine various activities on interface development for ceramic-matrix composites (CMCs) intended for high-temperature applications. While several articles have been published on the subject of CMC interfaces, the purpose of this report is to describe the various ongoing efforts on interface concepts, material selection, and issues related to processing methods employed for developing interface coatings. The most exciting and new development in the field is the discovery of monazite as a potential interface material for mullite- and alumina-based composites. Monazite offers two critical properties to the CMC system; a weakly bonded layer due to its non-wetting behavior and chemical compatibility with both alumina and mullite up to very high temperatures (> 1,600 C). Other interesting concepts with intensive material development efforts are also being pursued and a brief discussion of these are given in the main text. While demonstration of new interface concepts seems to be the primary objective in most studies, difficulties in processing of interface coatings and designing reliable test methods for determining interface properties have actually retarded the progress. Some of the concepts appear to be simple in nature but require sophisticated processing schemes to develop the coatings. Multilayered coatings with each layer serving specific function are also being proposed. Recent studies also show that significant degradation in fiber strength (30--50%) can result from merely applying the interface coating. These factors have compounds the complexity of interface tailoring in CMCs leading to a need for specific solution for a specific CMC system.

  1. Effect of coating Straumann Bone Ceramic with Emdogain on mesenchymal stromal cell hard tissue formation.

    Science.gov (United States)

    Mrozik, Krzysztof Marek; Gronthos, Stan; Menicanin, Danijela; Marino, Victor; Bartold, P Mark

    2012-06-01

    Periodontal tissue engineering requires a suitable biocompatible scaffold, cells with regenerative capacity, and instructional molecules. In this study, we investigated the capacity of Straumann Bone Ceramic coated with Straumann Emdogain, a clinical preparation of enamel matrix protein (EMP), to aid in hard tissue formation by post-natal mesenchymal stromal cells (MSCs) including bone marrow stromal cells (BMSCs) and periodontal ligament fibroblasts (PDLFs). MSCs were isolated and ex vivo-expanded from human bone marrow and periodontal ligament and, in culture, allowed to attach to Bone Ceramic in the presence or absence of Emdogain. Gene expression of bone-related proteins was investigated by real time RT-PCR for 72 h, and ectopic bone formation was assessed histologically in subcutaneous implants of Bone Ceramic containing MSCs with or without Emdogain in NOD/SCID mice. Alkaline phosphatase activity was also assessed in vitro, in the presence or absence of Emdogain. Collagen-I mRNA was up-regulated in both MSC populations over the 72-h time course with Emdogain. Expression of BMP-2 and the osteogenic transcription factor Cbfa-1 showed early stimulation in both MSC types after 24 h. In contrast, expression of BMP-4 was consistently down-regulated in both MSC types with Emdogain. Up-regulation of osteopontin and periostin mRNA was restricted to BMSCs, while higher levels of bone sialoprotein-II were observed in PDLFs with Emdogain. Furthermore, alkaline phosphatase activity levels were reduced in both BMSCs and PDLFs in the presence of Emdogain. Very little evidence was found for ectopic bone formation following subcutaneous implantation of MSCs with Emdogain-coated or -uncoated Bone Ceramic in NOD/SCID mice. The early up-regulation of several important bone-related genes suggests that Emdogain may have a significant stimulatory effect in the commitment of mesenchymal cells to osteogenic differentiation in vitro. While Emdogain inhibited AP activity and appeared

  2. Photocatalytic and biocidal activities of novel coating systems of mesoporous and dense TiO₂-anatase containing silver nanoparticles.

    Science.gov (United States)

    Roldán, María V; de Oña, Paula; Castro, Yolanda; Durán, Alicia; Faccendini, Pablo; Lagier, Claudia; Grau, Roberto; Pellegri, Nora S

    2014-10-01

    Here we describe the development of novel nanostructured coating systems with improved photocatalytic and antibacterial activities. These systems comprise a layer of SiO2 followed by a layer of mesoporous or dense TiO2-anatase, and doping with silver nanoparticles (Ag NPs). The coatings were synthesized via a sol-gel technique by combining colloidal Ag NPs with TiO2 and SiO2 sols. The photocatalytic activity was studied through methyl orange decomposition under UV light. Results showed a great increase of photocatalytic activity by Ag NPs doping. The most active photocatalyst corresponded to the Ag-SiO2/TiO2 mesoporous system, associated with the porosity of the coatings and with the decrease of e-h recombination for the presence of Ag NPs. All the TiO2 coatings showed a strong bactericidal activity against planktonic forms of Gram-negative (enterohemorrhagic Escherichia coli) and Gram-positive (Listeria monocytogenes) pathogens, as well as a strong germicidal effect against deadly spores of human gas gangrene- and anthrax-producing bacteria (Clostridium perfringens and Bacillus anthracis, respectively). The bactericidal and sporocidal activity was improved by doping the coatings with Ag NPs, even more when nanoparticles were in the outer layer of TiO2, because they are more accessible to the environment. The mechanisms responsible for the increase of photocatalytic and bactericidal behaviors related to Ag NP doping were studied by spectroscopic ellipsometry, UV-vis spectroscopy, photoluminescence and anodic stripping voltammetry. It was found that the separation of the electron-hole pair contributed to the enhancement of photocatalysis, whereas the effect of the local electric field reinforcement was probably present. A possible involvement of a decrease of band-gap energy and dispersion by silver nanoparticles is ruled out. bactericidal efficacy was increased by Ag(+) ion release. Overall, the results included in this article show that the architecture of the

  3. Influence of Additive Silica on the Laser Melting of the Ceramic Coatings

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The influence of additive silica on the microstructure of plasma sprayed Al2O3 and Al2O3+13 wt pct TiO2 ceramiccoatings at laser melting has been investigated in this study. At the laser melting, additive silica in Al2O3 ceramiccoating can reduce the stress of cooling shrinkage generated during solidification. Moreover, silica can render finersize of grains of the melting layer and form continuous glassy matter around the grain boundaries so as to reducefurther the cooling stresses and to suppress the formation and spreading of cracks. On the other hand, at the lasermelting, TiO2 reacts with Al2O3 and transforms into TiAl2Os. The latter new phase has great and anisotropiccoefficients of thermal expansion leading to big and asymmetrical stresses and thus to form cracks in the meltinglayer of Al2O3+13 wt pct TiO2 coating. Due to the fact that the influence of additive silica on the suppression of theformation of cracks is rather limited and cannot counterbalance the negative effect of TiAl2O5, thus the melting layerof Al2O3+13 wt pct TiO2 coating doped with 3 wt pct SiO2 cracks also. Nevertheless, TiO2 can greatly developthe wear resistance of the ceramic coating as sprayed or laser melted.

  4. Liquid spreading on ceramic-coated carbon nanotube films and patterned microstructures

    Science.gov (United States)

    Zhao, Hangbo; Hart, A. John

    2015-11-01

    We study the capillary-driven liquid spreading behavior on films and microstructures of ceramic-coated vertically aligned carbon nanotubes (CNTs) fabricated on quartz substrates. The nanoscale porosity and micro-scale dimensions of the CNT structures, which can be precisely varied by the fabrication process, enable quantitative measurements that can be related to analytical models of the spreading behavior. Moreover, the conformal alumina coating by atomic layer deposition (ALD) prevents capillary-induced deformation of the CNTs upon meniscus recession, which has complicated previous studies of this topic. Washburn-like liquid spreading behavior is observed on non-patterned CNT surfaces, and is explained using a scaling model based on the balance of capillary driving force and the viscous drag force. Using these insights, we design patterned surfaces with controllable spreading rates and study the contact line pinning-depinning behavior. The nanoscale porosity, controllable surface chemistry, and mechanical stability of coated CNTs provide significantly enhanced liquid-solid interfacial area compared to solid microstructures. As a result, these surface designs may be useful for applications such as phase-change heat transfer and electrochemical energy storage. Funding for this project is provided by the National Institutes of Health and the MIT Center for Clean Water and Clean Energy supported by the King Fahd University of Petroleum and Minerals.

  5. Development of Thermal Spraying and Coating Techniques by Using Thixotropic Slurries Including Metals and Ceramics Particles

    Science.gov (United States)

    Kirihara, S.; Itakura, Y.; Tasaki, S.

    2013-03-01

    Thermal nanoparticles coating and microlines patterning were newly developed as novel technologies to fabricate fine ceramics layers and geometrical intermetallics patterns for mechanical properties modulations of practical alloys substrates. Nanometer sized alumina particles were dispersed into acrylic liquid resins, and the obtained slurries were sputtered by using compressed air jet. The slurry mists could blow into the arc plasma with argon gas spraying. On stainless steels substrates, the fine surface layers with high wear resistance were formed. In cross sectional microstructures of the coated layers, micromater sized cracks or pores were not observed. Subsequently, pure aluminum particles were dispersed into photo solidified acrylic resins, and the slurry was spread on the stainless steel substrates by using a mechanical knife blade. On the substrates, microline patterns with self similar fractal structures were drawn and fixed by using scanning of an ultra violet laser beam. The patterned pure metal particles were heated by the argon arc plasma spray assisting, and the intermetallics or alloys phases with high hardness were created through reaction diffusions. Microstructures in the coated layers and the patterned lines were observed by using a scanning electron microscopy.

  6. Effects of silica coating and silane surface conditioning on the bond strength of rebonded metal and ceramic brackets

    Directory of Open Access Journals (Sweden)

    Saadet Atsü

    2011-06-01

    Full Text Available OBJECTIVE: The aim of this study was to evaluate the effects of tribochemical silica coating and silane surface conditioning on the bond strength of rebonded metal and ceramic brackets. MATERIAL AND METHODS: Twenty debonded metal and 20 debonded ceramic brackets were randomly assigned to receive one of the following surface treatments (n=10 for each group: (1 sandblasting (control; (2 tribochemical silica coating combined with silane. Brackets were rebonded to the enamel surface on the labial and lingual sides of premolars with a light-polymerized resin composite. All specimens were stored in distilled water for 1 week and then thermocycled (5,000 cycles between 5-55ºC. Shear bond strength values were measured using a universal testing machine. Student's t-test was used to compare the data (α=0.05. Failure mode was assessed using a stereomicroscope, and the treated and non-treated bracket surfaces were observed by scanning electron microscopy. RESULTS: Rebonded ceramic brackets treated with silica coating followed by silanization had significantly greater bond strength values (17.7±4.4 MPa than the sandblasting group (2.4±0.8 MPa, P<0.001. No significant difference was observed between the rebonded metal brackets treated with silica coating with silanization (15±3.9 MPa and the sandblasted brackets (13.6±3.9 MPa. Treated rebonded ceramic specimens primarily exhibited cohesive failure in resin and adhesive failure at the enamel-adhesive interface. CONCLUSIONS: In comparison to sandblasting, silica coating with aluminum trioxide particles followed by silanization resulted in higher bond strengths of rebonded ceramic brackets.

  7. Application of design of experiment on electrophoretic deposition of glass-ceramic coating materials from an aqueous bath

    Indian Academy of Sciences (India)

    Someswar Datta

    2000-04-01

    A process for application of abrasion- or corrosion-resistant glass-ceramic coating materials on metal substrate by electrophoretic deposition technique in an aqueous medium has been described. The effects of various process parameters, e.g. coating material concentration, time of deposition, applied current, pH of the suspension and concentration of the polymeric dispersant on the deposition efficiency have been studied. The process has been studied using a 23-factorial design technique of three independent variables; i.e. coating material concentration, applied current, and the time taken to achieve the best combination. The regression equation obtained explains the experimental results satisfactorily.

  8. Growth process and corrosion resistance of ceramic coatings of micro-arc oxidation on Mg-Gd-Y magnesium alloys

    Institute of Scientific and Technical Information of China (English)

    王萍; 李建平; 郭永春; 杨忠

    2010-01-01

    The regulation of ceramic coating formed by micro-arc oxidation on Mg-11Gd-1Y-0.5Zn (wt.%) magnesium alloys was investigated by scanning electron microscopy (SEM) and X-ray diffractometer (XRD). The relation of phase structure and corrosion resistance of MgO coating formed by micro-arc oxidation in different growth stages was analyzed. The results showed that the growth of coating accorded with linear regularity in the initial stage of micro-arc oxidation, which was the stage of anodic oxidation controlled ...

  9. Stabilization of the high-temperature phases in ceramic coatings on zirconium alloy produced by plasma electrolytic oxidation

    Science.gov (United States)

    Apelfeld, A. V.; Betsofen, S. Y.; Borisov, A. M.; Vladimirov, B. V.; Savushkina, S. V.; Knyazev, E. V.

    2016-09-01

    The composition and structure of ceramic coatings obtained on Zr-1%Nb alloy by plasma electrolytic oxidation (PEO) in aqueous electrolyte comprising 2 g/L KOH, 6 g/L NaAlO2 and 2 g/L Na2SiO3 with addition of yttria nanopowder, have been studied. The PEO coatings of thickness ∼⃒20 μm were studied using scanning electron microscopy, X-ray microanalysis and X-ray phase analysis. Additives in the electrolyte of yttria nanopowder allowed stabilizing the high-temperature tetragonal and cubic zirconia in the coating.

  10. Characterization of a biomimetic coating on dense and porous titanium substrates

    Energy Technology Data Exchange (ETDEWEB)

    Rocha, M.N. da; Pereira, L.C. [Coordenacao dos Programas de Pos-Graduacao de Engenharia (PEMM/COPPE/UFRJ), RJ (Brazil). Programa de Engenharia Metalurgica e de Materiais; Ribeiro, A.A.; Oliveira, M.V. de, E-mail: marize.varella@int.gov.b [Instituto Nacional de Tecnologia (INT), Rio de Janeiro, RJ (Brazil); Andrade, M.C. de [Universidade do Estado do Rio de Janeiro (IPRJ/UERJ), Nova Friburgo, RJ (Brazil). Inst. Politecnico

    2010-07-01

    Bioactive materials have been studied as coatings on bioinert subtracts. Thus, it is possible to combine the bioactivity of materials such as calcium phosphate with the excellent mechanical properties of metals. Titanium (Ti) implants can be bioactivated by a biomimetic precipitation method. This study introduces a biomimetic method under a simplified solution (SS) with calcium and phosphorus ions. As substrates, commercially pure Ti sheet and micro-porous Ti samples produced by powder metallurgy were used. The substrates were submitted to chemical and heat treating and then immersed in the SS for 7, 14, 21 days. Surface roughness was evaluated by confocal scanning optical microscopy. Coating characterization was performed by scanning electron microscopy and high resolution X-ray diffraction (XRD). The results showed calcium phosphate crystal morphologies observed in all samples, which was confirmed by XRD phase identifications. These results reveal the solution potential for coating Ti substrates. (author)

  11. Microstructure, bonding strength and thermal shock resistance of ceramic coatings on steels prepared by plasma electrolytic oxidation

    Science.gov (United States)

    Wang, Yunlong; Jiang, Zhaohua; Yao, Zhongping

    2009-11-01

    Ceramic coatings were successfully prepared on steel by plasma electrolytic oxidation (PEO) in aluminate electrolyte and silicate electrolyte, respectively. The microstructure of the coatings including surface morphology, phase and element composition were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The bonding strength between the ceramic coating and the substrate was tested using different methods including tensile tests and shearing tests. The thermal shock resistance of the coatings was also evaluated. The results indicated that coatings obtained in both electrolytes were porous and coarse. The average diameters of the pores were below 10 μm. PEO coatings obtained in aluminate electrolyte were composed of Fe 3O 4 and FeAl 2O 4, while those obtained in silicate electrolyte were in a noncrystal state. PEO coatings obtained in aluminate electrolyte showed similar change trend of tensile strength and shearing strength with increasing treating time, namely, a relatively high values with middle time treating and low value with short and long time treating. The best coating was the samples treated with 30 min, whose tensile strength was 20.6 MPa and shearing strength was 16 MPa. The tensile strength and shearing strength of coatings obtained in silicate electrolyte were not strongly influenced by the treating time, the values of which were range in 14 ± 2 MPa and 11 ± 2 MPa, respectively. Coatings obtained in both electrolytes showed the best thermal shock resistance with middle time treating. Coatings obtained in silicate electrolyte show a little better thermal shock resistance than those obtained in aluminate electrolyte.

  12. Calcium Phosphate Coating on Al2 O3 Ceramics by a Biomimetic Method Using Electric Pulse Technique

    Institute of Scientific and Technical Information of China (English)

    JIN Zhengguo; SHI Yong; GUO Wenli; WANG Ying; QIU Jijun

    2005-01-01

    The preparation of calcium phosphate (CP) coating on alumina ceramics using electric pulse stimulating method has been investigated. The cup-shaped alumina ceramics were soaked in a simulated body fluid (SBF), and a square pulse potential with frequency of 1 Hz and voltage of 110 V was applied between the inner and outer surfaces of the alumina cup. Surface morphology of CP coatings during different deposition periods was observed by a Philips XL-30 scanning electron microscope (SEM). Compositional analysis was examined by EDAX. The mechanism of nucleation and growth of CP coating was discussed. SEM result indicates that the coating comprises of a large number of tiny needle-like grains and has a porous microstructure. There is a strong bond between the deposited layer and Al2O3 substrate, which may be due to the gentle growth of the biomimetic method. The EDAX analysis indicates that main composition of the coating is calcium and phosphor. The formation of CP coating may be contributed to the stimulation of electric pulse and the high ions concentration which is 1.5 times of the concentration of SBF solution (1.5SBF solution). Such surface functionalization method by electric pulse potential can be used to prepare CP coating on various electric-insulating bioinert materials for improving their bioactive character.

  13. Improvement in the properties of plasma-sprayed metallic, alloy and ceramic coatings using dry-ice blasting

    Science.gov (United States)

    Dong, Shujuan; Song, Bo; Hansz, Bernard; Liao, Hanlin; Coddet, Christian

    2011-10-01

    Dry-ice blasting, as an environmental-friendly method, was introduced into atmospheric plasma spraying for improving properties of metallic, alloy and ceramic coatings. The deposited coatings were then compared with coatings plasma-sprayed using conventional air cooling in terms of microstructure, temperature, oxidation, porosity, residual stress and adhesion. It was found that a denser steel or CoNiCrAlY alloy coating with a lower content of oxide can be achieved with the application of dry-ice blasting during the plasma spraying. In addition, the adhesive strength of Al 2O 3 coating deposited with dry-ice blasting exceeded 60 MPa, which was nearly increased by 30% compared with that of the coating deposited with conventional air cooling. The improvement in properties of plasma-sprayed metallic, alloy and ceramic coatings caused by dry-ice blasting was attributed to the decrease of annulus-ringed disk like splats, the better cooling efficiency of dry-ice pellets and even the mechanical effect of dry-ice impact.

  14. Influences of current density on tribological characteristics of ceramic coatings on ZK60 Mg alloy by plasma electrolytic oxidation.

    Science.gov (United States)

    Wu, Xiaohong; Su, Peibo; Jiang, Zhaohua; Meng, Song

    2010-03-01

    Current density is a key factor of plasma electrolytic oxidation process. Its influences on structure, mechanical, and tribological characteristics of ceramic coatings on ZK60 Mg alloy by pulsed bipolar microplasma oxidation in Na(3)PO(4) solution were studied in this paper. Thickness, structure, composition, mechanical property, and tribological characteristics of the coatings were studied by eddy current coating thickness gauge, scanning electron microscope (SEM), X-ray diffraction (XRD), nanoindentation measurements, and ball-on-disk friction testing. The results show that all the coatings prepared under different current densities are composed of MgO phase. The amount of MgO phase, thickness and friction coefficient of the coatings increased with the increasing current density. Among three ceramic coatings produced under three current densities, the coating produced under the current density of 7 A/dm(2) got the highest nanohardness and lowest wear rate with the value of 1.7 GPa and 1.27 x 10(-5) mm(3)/Nm.

  15. Microstructure and oxidation resistance of reactive plasma clad Cr7C3 /γ-Fe ceramic composite coating

    Institute of Scientific and Technical Information of China (English)

    Liu Junbo

    2007-01-01

    A new type oxidation resistance in situ Cr7C3/γ-Fe ceramic composite coating was fabricated on hardened and tempered grade C steel by reactive plasma clad with Fe-Cr-C alloy powders. The oxidation resistance of the ceramic composite coating was investigated under the test condition of 900℃ and 50 hours. The results indicate that the coating has a rapidly solidified microstructure consisting of blocky primary Cr7C3 and the inter-blocky Cr7C3/γ-Fe eutectics and is metallurgically bonded to the hardened and tempered grade C steel substrate. The high temperature oxidation resistance of the coating is up to 1.9 times higher than that of grade C steel. The oxidation kinetics curve of the coating is conforming to the parabolic-rate law equation. The excellent oxidation resistance of the coating is mainly attributed to the continuous oxide films which consist of Cr2O3 and Fe2O3. The continuous oxide films can prevent the inner part of the coating from being further oxidized.

  16. Topical report to Morgantown Energy Technology Center for the interfacial coatings for ceramic-matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-01-09

    This report summarizes the task conducted to examine various activities on interface development for ceramic-matrix composites (CMCs) intended for high-temperature applications. While several articles have been published on the subject of CMC interfaces, the purpose of this report is to describe the various ongoing efforts on interface concepts, material selection, and issues related to processing methods employed for developing interface coatings. The most exciting and new development in the field is the discovery of monazite as a potential interface material for mullite- and alumina-based composites. Monazite offers two critical properties to the CMC system; a weakly bonded layer due to its non-wetting behavior and chemical compatibility with both alumina and mullite up to very high temperatures (> 1,600 C). A description of the Department of Energy-related activities and some thoughts on processing issues, interface testing, and effects of processing on fiber strength are given.

  17. High temperature (salt melt) corrosion tests with ceramic-coated steel

    Energy Technology Data Exchange (ETDEWEB)

    Schütz, Adelheid [University Bayreuth, Metals and Alloys, Ludwig-Thoma-Str. 36b, D-95447 Bayreuth (Germany); Günthner, Martin; Motz, Günter [University Bayreuth, Ceramic Materials Engineering, L.-Thoma-Str. 36b, D-95447 Bayreuth (Germany); Greißl, Oliver [EnBW Kraftwerke AG, Schelmenwasenstraße 13-15, D-70567 Stuttgart (Germany); Glatzel, Uwe, E-mail: uwe.glatzel@uni-bayreuth.de [University Bayreuth, Metals and Alloys, Ludwig-Thoma-Str. 36b, D-95447 Bayreuth (Germany)

    2015-06-01

    Thermal recycling of refuse in waste-to-energy plants reduces the problems connected to waste disposal, and is an alternative source of electric energy. However, the combustion process in waste incinerators results in a fast degradation of the steam-carrying superheater steel tubes by corrosive attack and abrasive wear. Higher firing temperatures are used to increase their efficiency but lead to higher corrosion rates. It is more economical to apply protective coatings on the superheater steel tubes than to replace the base material. In-situ tests were conducted in a waste-to-energy plant first in order to identify and quantify all involved corrosive elements. Laboratory scale experiments with salt melts were developed accordingly. The unprotected low-alloyed steel displayed substantial local corrosion. Corrosion was predominant along the grain boundaries of α-ferrite. The corrosion rate was further increased by FeCl{sub 3} and a mixture of HCL and FeCl{sub 3}. Coatings based on pre-ceramic polymers with specific filler particles were engineered to protect superheater tubes. Tests proved their suitability to protect low-alloYed steel tubes from corrosive attack under conditions typical for superheaterS in waste incinerators, rendering higher firing temperatures in waste-to-energy plants possible. - Highlights: • Corrosion wall thickness losses of 400 μm/2 weeks occurred in a waste incinerator. • Abrasion is a major problem on superheater tubes in waste incinerators. • Laboratory salt melt tests can simulate metal corrosion in waste incinerators. • Corrosion protection coatings for steel (temperature: max. 530 °C) were developed. • Higher steam temperatures are possible in WIs with the developed coatings.

  18. Materials and vapour-phase techniques for the synthesis of ceramic coatings

    Directory of Open Access Journals (Sweden)

    Albella, J. M.

    2007-08-01

    Full Text Available A survey on recent advances in the synthesis of hard ceramic coatings is given, including materials processes and techniques. Emphasis is made on the parameters which control the coating properties (crystalline structure, morphology, etc, namely arrival energy of the atoms to the growing surface and substrate temperature. Some relevant coating materials are discussed in relation to their applications either as hard protective coatings or with decorative purposes, namely: the family of metal nitrides, carbides, and oxides, in different layer structures (monolithic, multilayers and nanocomposites and ternary compounds of the BCN system.

    Se hace un descripción de los avances recientes en la síntesis de recubrimientos duros de tipo cerámico, depositados mediante técnicas de deposición en fase vapor. Se dedica especial atención a los parámetros del proceso de deposición que controlan las propiedades finales de las capas (estructura cristalina, morfología, etc, tales como la energía de llegada de los átomos a las superficie en crecimiento, y la temperatura. Finalmente, se hace una revisión de los materiales más relevantes en lo que se refiere a sus aplicaciones como recubrimientos duros y protectores, o como recubrimientos decorativos, entre ellos, la familia de los nitruros, carburos y óxidos metálicos, depositados en diversos tipos de estructuras (monolíticas, multicapas y nanocomposites, y los compuestos ternarios del sistema BCN.

  19. Effects of B2O3 content and sintering temperature on crystallization and microstructure of CBS glass-ceramic coatings

    Science.gov (United States)

    Li, Pengyang; Wang, Shubin; Liu, Jianggao; Feng, Mengjie; Yang, Xinwang

    2015-11-01

    Borosilicate glass-ceramics precursors with varying compositional ratios in the CaO-SiO2-B2O3 (CBS) system were synthesized by sol-gel method. The precursors were calcined at 1200 °C for 2 h to form glass powders. The glass-ceramics were prepared by overlaying glass slurries on the substrates before sintering at different temperatures. The as-prepared glasses and glass-ceramics were characterized by differential scanning calorimetry and X-ray diffraction. The crystallization activation energies (Ec) were calculated using the Kissinger method from DSC results. The morphology and crystallization behavior of the glass-ceramics were monitored by scanning electron microscopy. Both glass transition and crystallization temperatures decreased, however, the metastable zone increased. The Ec values of CBS glasses and glass-ceramics were 254.1, 173.2 and 164.4 kJ/mol with increasing B2O3 content, whereas that of the calcined G3 glass was 104.9 kJ/mol. Finally, the coatings were prepared at a low temperature (700 °C). The crystals that grew on the surface of multilayer coatings demonstrated heterogeneous surface nucleation and crystallization after heat-treatment from 700 °C to 850 °C for 4 h.

  20. Interdisciplinary approach to cell-biomaterial interactions: biocompatibility and cell friendly characteristics of RKKP glass-ceramic coatings on titanium.

    Science.gov (United States)

    Ledda, Mario; De Bonis, Angela; Bertani, Francesca Romana; Cacciotti, Ilaria; Teghil, Roberto; Lolli, Maria Grazia; Ravaglioli, Antonio; Lisi, Antonella; Rau, Julietta V

    2015-06-01

    In this work, titanium (Ti) supports have been coated with glass-ceramic films for possible applications as biomedical implant materials in regenerative medicine. For the film preparation, a pulsed laser deposition (PLD) technique has been applied. The RKKP glass-ceramic material, used for coating deposition, was a sol-gel derived target of the following composition: Ca-19.4, P-4.6, Si-17.2, O-43.5, Na-1.7, Mg-1.3, F-7.2, K-0.2, La-0.8, Ta-4.1 (all in wt%). The prepared coatings were compact and uniform, characterised by a nanometric average surface roughness. The biocompatibility and cell-friendly properties of the RKKP glass-ceramic material have been tested. Cell metabolic activity and proliferation of human colon carcinoma CaCo-2 cells seeded on RKKP films showed the same exponential trend found in the control plastic substrates. By the phalloidin fluorescence analysis, no significant modifications in the actin distribution were revealed in cells grown on RKKP films. Moreover, in these cells a high mRNA expression of markers involved in protein synthesis, proliferation and differentiation, such as villin (VIL1), alkaline phosphatase (ALP1), β-actin (β-ACT), Ki67 and RPL34, was recorded. In conclusion, the findings, for the first time, demonstrated that the RKKP glass-ceramic material allows the adhesion, growth and differentiation of the CaCo-2 cell line.

  1. Effect of nano-size nickel particles on wear resistance and high temperature oxidation resistance of ultrafine ceramic coating

    Institute of Scientific and Technical Information of China (English)

    古一; 夏长清; 李佳; 吴安如

    2004-01-01

    In order to improve the wear resistance and high temperature oxidation resistance of titanium and titanium alloy, the high temperature ultra fine ceramic coating containing nano-size nickel particles was prepared by flow coat method on the surface of industrially pure titanium TB1-0. The effects of nano-size nickel particles on the wear resistance and high temperature oxidation resistance of coating substrate system were investigated through oxidation kinetics experiment and wear resistance test. The morphologies of the specimens were examined by means of optical microscopy, scanning electron microscopy and X-ray diffraction. The results show that the high temperature ultra fine ceramic coating has notable protection effect on industrially pure titanium TB1-0 from oxidation. The oxidation and wear resistance properties of the coating can be effectively improved by adding nano-size nickel particles. The decreases from 1. 1 to 0. 6 by adding nano-size nickel particles, and the coating containing 10% (mass fraction) nano-size nickel shows the optimum properties.

  2. Erosion and corrosion of ceramic-metallic coatings and stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Bjordal, M.

    1995-04-01

    Simultaneous corrosion and erosion is a well-known problem in many environments, for instance in hydroelectric power plants and in oil production systems. This thesis presents a study of the combined effect of corrosion and erosion for some thermal spray ceramic-metallic coatings (cemented carbides) and a duplex stainless steel. By measuring the two effects separately and comparing them to the total material loss obtained when they occur simultaneously, it has been possible to reveal the relative contribution from the two deterioration mechanisms and how they interact. The materials were exposed to flowing aerated synthetic sea water containing silica particles. Specimens of various shapes were moved in the slurry. It is generally found that the corrosion percentage decreases when the erosivity of the environment is increased, for instance by increased flow velocity, and at the same time erosion plays a more important role. For all the materials tested the corrosion rate is increased by addition of particles to the flow. Differences are found between the thermal spray coatings. Small additions of Cr to the actively corroding Co matrix of the 83WC 17Co sample improve the corrosion resistance. Even if the amount of corrosion relative to the total weight loss rate is small, the corrosion can lead to a synergism of up to 90 %. Stainless steel does not exhibit a clear synergism. The computer code FLUENT was used for modelling the flow conditions. 79 refs., 67 figs., 29 tabs.

  3. Suppression effects of dental glass-ceramics with polarization-induced highly dense surface charges against bacterial adhesion.

    Science.gov (United States)

    Nozaki, Kosuke; Koizumi, Hiroki; Horiuchi, Naohiro; Nakamura, Miho; Okura, Toshinori; Yamashita, Kimihiro; Nagai, Akiko

    2015-01-01

    This study investigated the surface characteristics and antibacterial ability capacity of surface-improved dental glass-ceramics by an electrical polarization process. Commercially available dental glass-ceramic materials were electrically polarized to induce surface charges in a direct current field by heating. The surface morphology, chemical composition, crystal structure, and surface free energy (SFE) were evaluated using scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction, and water droplet methods, respectively. The antibacterial capacity was assessed by a bacterial adhesion test using Streptococcus mutans. Although the surface morphology, chemical composition, and crystal structure were not affected by electrical polarization, the polar component and total SFE were enhanced. After 24 h incubation at 37ºC, bacterial adhesion to the polarized samples was inhibited. The electrical polarization method may confer antibacterial properties on prosthetic devices, such as porcelain fused to metal crowns or all ceramic restorations, without any additional bactericidal agents.

  4. Crack-free cutting of thick and dense ceramics with CO 2 laser by single-pass process

    Science.gov (United States)

    Ji, Lingfei; Yan, Yinzhou; Bao, Yong; Jiang, Yijian

    2008-10-01

    This paper presents a laser crack-free cutting method of Al 2O 3 ceramics by single-pass process in internal straight and curve profiles. The thickness and theoretical density of the ceramics are up to 10 mm and about 99%, respectively. The effective cutting speed is about 0.23-0.42 mm/s corresponding to the laser head moving speed of 3 mm/s. The cutting process based on close-piercing lapping of piercing time of 0.1-0.5 s and piercing pitch of 0.03-0.05 mm is divided into two continuous stages. Appropriate time slot for each piercing, high peak power of 3500 W and low cycle duty (laser crack-free cutting method is a promising method to achieve complex profiles of ceramic cuts.

  5. Study on Preparation of Magnesium Alloy with Chemical Conversion Film Binder Ceramic Coating Bottom%用化学转化膜制备镁合金陶瓷涂层粘结底层研究

    Institute of Scientific and Technical Information of China (English)

    赵斌; 马壮; 张济民; 李欣棉

    2013-01-01

    The conversion of chromate salt, conversion of phosphate and phosphoric acid potassium permanganate conversion were selected to prepare chemical conversion film on magnesium alloy surface. The results indicate that the chromate salt conversion film and conversion of phosphate film on MB2 magnesium surface are un-dense, can not have barrier, shall not be applicable as ceramic coatings transition layers. Preparation of phosphoric acid potassium permanganate conversion film may slow or prevent ceramic pulp with the magnesium substrate for the reaction, be suitable to serve as the ceramic coating transition layers.%选用铬酸盐转化、磷酸盐转化及磷酸-高锰酸钾转化方法制备镁合金表面的化学转化膜.结果表明:在MB2镁合金表面制备的铬酸盐转化膜、磷酸盐转化膜均不够致密,不能起到阻隔作用,均不适合作为陶瓷涂层的过渡层使用;制备的磷酸-高锰酸钾转化膜可以减缓或阻止陶瓷料浆与镁合金基体的反应,适合作为陶瓷涂层的过渡层使用.

  6. INVESTIGATION OF PROCESSES ON TREATMENT OF PLASMA COATINGS MADE OF MATERIALS BASED ON MULTIFUNCTIONAL OXIDE CERAMICS WITH LASER IRRADIATION IMPULSES

    Directory of Open Access Journals (Sweden)

    V. A. Okovity

    2014-01-01

    Full Text Available The purpose of the presented paper is to optimize technological parameters of hardening high-energy processing used for sprayed coatings made of materials based on oxide ceramics with inclusions of solid lubricant. The paper presents results of the investigations on influence of power density and total number of laser irradiation impulses in a spot treatment on thickness of treated coating layers made of materials based on oxide ceramics. The considered wear-resistant coatings require increased cohesive and adhesive strength. Therefore, the total number of impulses should ensure melting and sealing of the coatings along the whole thickness that will fully contribute to obtain hardened nano-crystalline and amorphous structures.The work is based on complex metallography, X-ray diffraction and electron-microscopic investigations on modified structural elements of composite coatings being treated with highly concentrated energy sources. The following main processes of hardened plasma coating formations have been revealed in the paper: com paction of sprayed materials due to thermal and shock-wave impacts of laser irradiation impulses. In this case material porosity is decreasing, cohesive and adhesive strength of coatings is increasing, grain structure is crushed, amorphous and nano-crystalline phases of higher strength are formed all these facts are evidenced by an increase in average micro-hardness of deposited compositions. Duration of thermal laser irradiation impulse impact on the material is sufficient to activate chemical processes in the boundaries of main phases of the composite coating. This leads to formation of finely dispersed (including nanoparticle size compounds that strengthen boundaries of the main phases and the coating as a whole. This is confirmed by the results of an X-ray diffraction analysis.

  7. Durability and Design Issues of Thermal/environmental Barrier Coatings on Sic/sic Ceramic Matrix Composites Under 1650 C Test Conditions

    Science.gov (United States)

    Zhu, Dong-Ming; Choi, Sung R.; Ghosn, Louis J.; Miller, Robert A.

    2004-01-01

    Ceramic thermal/environmental barrier coatings for SiC-based ceramics will play an increasingly important role in future gas turbine engines because of their ability to effectively protect the engine components and further raise engine temperatures. However, the coating durability remains a major concern with the ever-increasing temperature requirements. Currently, advanced T/EBC systems, which typically include a high temperature capable zirconia- (or hahia-) based oxide top coat (thermal barrier) on a less temperature capable mullite/barium-strontium-aluminosilicate (BSAS)/Si inner coat (environmental barrier), are being developed and tested for higher temperature capability Sic combustor applications. In this paper, durability of several thermal/environmental barrier coating systems on SiC/SiC ceramic matrix composites was investigated under laser simulated engine thermal gradient cyclic, and 1650 C (3000 F) test conditions. The coating cracking and delamination processes were monitored and evaluated. The effects of temperature gradients and coating configurations on the ceramic coating crack initiation and propagation were analyzed using finite element analysis (FEA) models based on the observed failure mechanisms, in conjunction with mechanical testing results. The environmental effects on the coating durability will be discussed. The coating design approach will also be presented.

  8. Synthesis and analysis of Mo-Si-B based coatings for high temperature oxidation protection of ceramic materials

    Science.gov (United States)

    Ritt, Patrick J.

    The use of Ni-based superalloys in turbine engines has all but been exhausted, with operating temperatures nearing the melting point of these materials. The use of ceramics in turbine engines, particularly ceramic matrix composites such as SiC/C and SiC/SiC, is of interest due to their low density and attractive mechanical properties at elevated temperatures. The same materials are also in consideration for leading edges on hypersonic vehicles. However, SiC-based composites degrade in high temperature environments with low partial pressures of oxygen due to active oxidation, as well as high temperature environments containing water or sand. The need for a protective external coating for SiC-based composites in service is obvious. To date, no coating investigated for SiC/C or SiC/SiC has been proven to be resistant to oxidation and corrosion at intermediate and high temperatures, as well as in environments deficient in oxygen. The Mo-Si-B coating shows great promise in this area, having been proven resistant to attack from oxidation at extreme temperatures, from water vapor and from calcia-magnesia-aluminosilicate (CMAS). The adaptation of the Mo-Si-B coating for ceramic materials is presented in detail here. Evaluation of the coating under a range of oxidation conditions as well as simulated re-entry conditions confirms the efficacy of the Mo-Si-B based coating as protection from catastrophic failure. The key to the oxidation and corrosion resistance is a robust external aluminoborosilica glass layer that forms and flows quickly to cover the substrate, even under the extreme simulated re-entry conditions. Suppression of active oxidation of SiC, which may occur during atmospheric re-entry and hypersonic flight trajectories, has also been examined. In order to adapt the Mo-Si-B based coating to low partial pressures of oxygen and elevated temperatures, controlled amounts of Al were added to the Mo-Si-B based coating. The resulting coating decreased the inward

  9. ESD coating of copper with TiC and TiB2 based ceramic matrix composites

    Science.gov (United States)

    Talas, S.; Mertgenç, E.; Gökçe, B.

    2016-08-01

    In automotive industry, the spot welding is a general practice to join smaller sections of a car. This welding is specifically carried out in short time and in an elevated number with certain pressure applied on copper electrodes. In addition, copper electrodes are expected to endure against cyclic mechanical pressure and temperature that is released during the passage of the current. The deformation and oxidation behaviour of copper electrodes during service appear with increasing temperature of medium and they also need to be cleaned and cooled or replaced for the continuation of joining process. The coating of copper electrodes with ceramic matrix composites can provide alternative excellent high temperature strength and ensures both economic and efficient use of resources. This study shows that the ESD coating of copper electrodes with a continuous film of ceramic phase ensures an improved resistance to thermal effects during the service and the change in content of film may be critical for cyclic alloying.

  10. Boosting the Detection Potential of Liquid Chromatography-Electron Ionization Mass Spectrometry Using a Ceramic Coated Ion Source

    Science.gov (United States)

    Magrini, Laura; Famiglini, Giorgio; Palma, Pierangela; Termopoli, Veronica; Cappiello, Achille

    2016-01-01

    Detection of target and non-target substances and their characterization in complex samples is a challenging task. Here we demonstrate that coating the electron ionization (EI) ion source of an LC-MS system with a sol-gel ceramic film can drastically improve the detection of high-molecular weight and high-boiling analytes. A new ion source coated with a ceramic material was developed and tested with a mixture of polycyclic aromatic hydrocarbons (PAH) with an increasing number of rings. Comparison of the results obtained with those for an uncoated stainless steel (SS) ion source shows a dramatic improvement in the MS signals, with a nearly 40-fold increase of the signal-to-noise ratio. We also demonstrate the ability of the new system to produce excellent chromatographic profiles for hard-to-detect hormones.

  11. Research on the Formation of Metal-Ceramic Surface Composite Coating by Wide-Band Laser Cladding

    Institute of Scientific and Technical Information of China (English)

    LIUShuo; ZHANGWei-ping; MAYu-tao

    2004-01-01

    Large-area in-situ synthesized TiB2 (TiB, Fe2B)-Fe metal-ceramic composite coating has been fabricated on medium carbon steel by laser cladding with the optimal laser parameters and overlapping coefficient. The bonding interfaces between the cladding layer and the matrix and among different tracks are excellent. Microanalysis on the cladding layer shows that the morphology is a little different from each other and the element distribution and the mechanical properties are unanimous in each track while the mechanical property of the cladding layer shows a gradual change from the surface to the matrix. The th-situ separating out thin ceramic phases in the coating contribute to the improving of its properties greatly.

  12. Research on the Formation of Metal-Ceramic Surface Composite Coating by Wide-Band Laser Cladding

    Institute of Scientific and Technical Information of China (English)

    LIU Shuo; ZHANG Wei-ping; MA Yu-tao

    2004-01-01

    Large-area in-situ synthesized TiB2 (TiB, Fe2B)-Fe metal-ceramic composite coating has been fabricated on medium carbon steel by laser cladding with the optimal laser parameters and overlapping coefficient. The bonding interfaces between the cladding layer and the matrix and among different tracks are excellent. Microanalysis on the cladding layer shows that the morphology is a little different from each other and the element distribution and the mechanical properties are unanimous in each track while the mechanical property of the cladding layer shows a gradual change from the surface to the matrix. The in-situ separating out thin ceramic phases in the coating contribute to the improving of its properties greatly.

  13. CORROSION RESISTANT CERAMIC COATING FOR X80 PIPELINE STEEL BY LOW-TEMPERATURE PACK ALUMINIZING AND OXIDATION TREATMENT

    OpenAIRE

    HUANG MIN; FU QIAN-GANG; WANG YU; ZHONG WEN-WU

    2013-01-01

    In this paper, we discuss the formation of ceramic coatings by a combined processing of low-temperature pack aluminizing and oxidation treatment on the surface of X80 pipeline steel substrates in order to improve the corrosion resistance ability of X80 pipeline steel. First, Fe-Al coating consisting of FeAl3 and Fe2Al5 was prepared by a low-temperature pack aluminizing at 803 K which was fulfilled by adding zinc in the pack powder. Pre-treatment of X80 pipeline steel was carried out through s...

  14. Reliability and effective thermal conductivity of three metallic-ceramic composite insulating coatings on cooled hydrogen-oxygen rockets

    Science.gov (United States)

    Price, H. G., Jr.; Schacht, R. L.; Quentmeyer, R. J.

    1973-01-01

    An experimental investigation of the structural integrity and effective thermal conductivity of three metallic-ceramic composite coatings was conducted. These coatings were plasma sprayed onto the combustion side of water-cooled, 12.7-centimeter throat diameter, hydrogen-oxygen rocket thrust chambers operating at 2.07 to 4.14 meganewtons per square meter chamber pressure. The metallic-ceramic composites functioned for six to 17 cycles and for as long as 213 seconds of rocket operations and could have probably provided their insulating properties for many additional cycles. The effective thermal conductivity of all the coatings was in the range of 0.7472 to 4.483 w/(m)(K), which makes the coatings a very effective thermal barrier. Photomicrographic studies of cross-sectioned coolant tubes seem to indicate that the effective thermal conductivity of the coatings is controlled by contact resistance between the particles, as a result of the spraying process, and not the thermal conductivity of the bulk materials.

  15. TEM analysis and wear resistance of the ceramic coatings on Q235 steel prepared by hybrid method of hot-dipping aluminum and plasma electrolytic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Lu Lihong [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Science and Research Department, Chinese People' s Armed Police Academy, Langfang 065000 (China); Zhang Jingwu [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Shen Dejiu, E-mail: sdj217@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Wu Lailei; Jiang Guirong [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Li Liang [State Key Laboratory of Automotive Safety and Energy, Tsinghua University, Beijing 100084 (China)

    2012-01-25

    Highlights: Black-Right-Pointing-Pointer Transmission electron microscopy (TEM) was firstly used to analyze the phase composition of the ceramic coatings. Black-Right-Pointing-Pointer The phase composition of the ceramic coatings is mainly amorphous phase and crystal Al{sub 2}O{sub 3} oxides. Black-Right-Pointing-Pointer The cross-section micro-hardness of the treated samples was investigated, the hardness of the ceramic coatings is about HV1300. Black-Right-Pointing-Pointer The wear resistance of the PEO samples is about 3 times higher than that of the heat treated 45 steel. - Abstract: The hybrid method of PEO and hot-dipping aluminum (HDA) was employed to deposit composite ceramic coatings on the surface of Q235 steel. The composition of the composite coatings was investigated with X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The cross-section microstructure and micro-hardness of the treated specimens were investigated and analyzed with scanning electron microscopy (SEM) and microscopic hardness meter (MHM), respectively. The wear resistance of the ceramic coatings was investigated by a self-made rubbing wear testing machine. The results indicate that metallurgical bonding can be observed between the ceramic coatings and the steel substrate. There are many micro-pores and micro-cracks, which act as the discharge channels and result of quick and non-uniform cooling of melted sections in the plasma electrolytic oxidation ceramic coatings. The phase composition of the ceramic coatings is mainly composed of amorphous phase and crystal Al{sub 2}O{sub 3} oxides. The crystal Al{sub 2}O{sub 3} phase includes {kappa}-Al{sub 2}O{sub 3}, {theta}-Al{sub 2}O{sub 3} and {beta}-Al{sub 2}O{sub 3}. The grain size of the {kappa}-Al{sub 2}O{sub 3} crystal is quite non-uniform. The hardness of the ceramic coatings is about HV1300 and 10 times higher than that of the Q235 substrate, which was favorable to the better wear resistance of the ceramic

  16. Environmental Barrier Coating Development for SiC/SiC Ceramic Matrix Composites: Recent Advances and Future Directions

    Science.gov (United States)

    Zhu, Dongming

    2016-01-01

    This presentation briefly reviews the SiC/SiC major environmental and environment-fatigue degradations encountered in simulated turbine combustion environments, and thus NASA environmental barrier coating system evolution for protecting the SiC/SiC Ceramic Matrix Composites for meeting the engine performance requirements. The presentation will review several generations of NASA EBC materials systems, EBC-CMC component system technologies for SiC/SiC ceramic matrix composite combustors and turbine airfoils, highlighting the temperature capability and durability improvements in simulated engine high heat flux, high pressure, high velocity, and with mechanical creep and fatigue loading conditions. This paper will also focus on the performance requirements and design considerations of environmental barrier coatings for next generation turbine engine applications. The current development emphasis is placed on advanced NASA candidate environmental barrier coating systems for SiC/SiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. The efforts have been also directed to developing prime-reliant, self-healing 2700F EBC bond coat; and high stability, lower thermal conductivity, and durable EBC top coats. Major technical barriers in developing environmental barrier coating systems, the coating integrations with next generation CMCs having the improved environmental stability, erosion-impact resistance, and long-term fatigue-environment system durability performance will be described. The research and development opportunities for turbine engine environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling will be briefly discussed.

  17. Single-source-precursor synthesis of dense SiC/HfCxN1-x-based ultrahigh-temperature ceramic nanocomposites

    Science.gov (United States)

    Wen, Qingbo; Xu, Yeping; Xu, Binbin; Fasel, Claudia; GuillonPresent Address: Forschungszentrum Jülich, Institut Für Energie-Und Klimaforschung 1: Werkstoffsynthese Und Herstellungsverfahren, Wilhelm-Johnen-Straße, D.-52425 Jülich., Olivier; Buntkowsky, Gerd; Yu, Zhaoju; Riedel, Ralf; Ionescu, Emanuel

    2014-10-01

    A novel single-source precursor was synthesized by the reaction of an allyl hydrido polycarbosilane (SMP10) and tetrakis(dimethylamido)hafnium(iv) (TDMAH) for the purpose of preparing dense monolithic SiC/HfCxN1-x-based ultrahigh temperature ceramic nanocomposites. The materials obtained at different stages of the synthesis process were characterized via Fourier transform infrared (FT-IR) as well as nuclear magnetic resonance (NMR) spectroscopy. The polymer-to-ceramic transformation was investigated by means of MAS NMR and FT-IR spectroscopy as well as thermogravimetric analysis (TGA) coupled with in situ mass spectrometry. Moreover, the microstructural evolution of the synthesized SiHfCN-based ceramics annealed at different temperatures ranging from 1300 °C to 1800 °C was characterized by elemental analysis, X-ray diffraction, Raman spectroscopy and transmission electron microscopy (TEM). Based on its high temperature behavior, the amorphous SiHfCN-based ceramic powder was used to prepare monolithic SiC/HfCxN1-x-based nanocomposites using the spark plasma sintering (SPS) technique. The results showed that dense monolithic SiC/HfCxN1-x-based nanocomposites with low open porosity (0.74 vol%) can be prepared successfully from single-source precursors. The average grain size of both HfC0.83N0.17 and SiC phases was found to be less than 100 nm after SPS processing owing to a unique microstructure: HfC0.83N0.17 grains were embedded homogeneously in a β-SiC matrix and encapsulated by in situ formed carbon layers which acted as a diffusion barrier to suppress grain growth. The segregated Hf-carbonitride grains significantly influenced the electrical conductivity of the SPS processed monolithic samples. While Hf-free polymer-derived SiC showed an electrical conductivity of ca. 1.8 S cm-1, the electrical conductivity of the Hf-containing material was analyzed to be ca. 136.2 S cm-1.A novel single-source precursor was synthesized by the reaction of an allyl hydrido

  18. In vitro and in vivo evaluation of zinc-modified ca-si-based ceramic coating for bone implants.

    Directory of Open Access Journals (Sweden)

    Jiangming Yu

    Full Text Available The host response to calcium silicate ceramic coatings is not always favorable because of their high dissolution rates, leading to high pH within the surrounding physiological environment. Recently, a zinc-incorporated calcium silicate-based ceramic Ca2ZnSi2O7 coating, developed on a Ti-6Al-4V substrate using plasma-spray technology, was found to exhibit improved chemical stability and biocompatibility. This study aimed to investigate and compare the in vitro response of osteoblastic MC3T3-E1 cells cultured on Ca2ZnSi2O7 coating, CaSiO3 coating, and uncoated Ti-6Al-4V titanium control at cellular and molecular level. Our results showed Ca2ZnSi2O7 coating enhanced MC3T3-E1 cell attachment, proliferation, and differentiation compared to CaSiO3 coating and control. In addition, Ca2ZnSi2O7 coating increased mRNA levels of osteoblast-related genes (alkaline phosphatase, procollagen α1(I, osteocalcin, insulin-like growth factor-I (IGF-I, and transforming growth factor-β1 (TGF-β1. The in vivo osteoconductive properties of Ca2ZnSi2O7 coating, compared to CaSiO3 coating and control, was investigated using a rabbit femur defect model. Histological and histomorphometrical analysis demonstrated new bone formation in direct contact with the Ca2ZnSi2O7 coating surface in absence of fibrous tissue and higher bone-implant contact rate (BIC in the Ca2ZnSi2O7 coating group, indicating better biocompatibility and faster osseointegration than CaSiO3 coated and control implants. These results indicate Ca2ZnSi2O7 coated implants have applications in bone tissue regeneration, since they are biocompatible and able to osseointegrate with host bone.

  19. Mechanical and tribological behavior of red clay ceramic tiles coated with fly ash powders by thermal spraying technique.

    Science.gov (United States)

    Peña-Rodríguez, G.; Dulce-Moreno, H.; Daza-Ramírez, J.; Orozco-Hernández, S.; Vargas-Galvis, F.

    2017-01-01

    The mechanical and tribological performance of red clay ceramic tiles uncoated and coated by oxy-fuel thermal spraying process from fly ash powders was evaluated. The ceramic tile substrates were manufactured by uniaxial pressing at 26.17 bar pressure, and sintered at 1100 °C. The coating thickness was determined based on the number of projection-cycles oxyacetylene flame over substrate. Coal fly ash coatings were deposited, with average thickness of 56.18±12.18 μm, 180.42±20.32 μm, and 258.26±25.88μm. The mechanical resistance to bending and wear by abrasion deep, were studied using ISO 10545-4 standards and ISO 10545-6 respectively; adhesion was measured using Elcometer equipment Type III according to ASTM D-4541-02 and the average roughness (Ra) was found according to ASTM standard D7127-13, using the profilometer Mitutoyo SJ 201. The surface morphology presented the heterogeneous molten or semi molten splats with average size of 35.262±3.48 micrometers with good adhesion, justifying increased mechanical resistance to bending by 5%, as well as wear by abrasion deep. These results contribute to the development of ceramic products with added value, to be used in various technological applications.

  20. Electrochemical promotion of propane oxidation on Pt deposited on a dense β"-Al2O3 ceramic Ag+ conductor

    Directory of Open Access Journals (Sweden)

    Michail eTsampas

    2013-08-01

    Full Text Available A new kind of electrochemical catalyst based on a Pt porous catalyst film deposited on a β"-Al2O3 ceramic Ag+ conductor was developed and evaluated during propane oxidation. It was observed that upon anodic polarization, the rate of propane combustion was significantly electropromoted up to 400%. Moreover, for the first time, exponential increase of the catalytic rate was evidenced during galvanostatic transient experiment in excellent agreement with EPOC equation.

  1. Electrochemical promotion of propane oxidation on Pt deposited on a dense β"-Al2O3 ceramic Ag+ conductor

    Science.gov (United States)

    Tsampas, Michail; Kambolis, Anastasios; Obeid, Emil; Lizarraga, Leonardo; Sapountzi, Foteini; Vernoux, Philippe

    2013-08-01

    A new kind of electrochemical catalyst based on a Pt porous catalyst film deposited on a β"-Al2O3 ceramic Ag+ conductor was developed and evaluated during propane oxidation. It was observed that upon anodic polarization, the rate of propane combustion was significantly electropromoted up to 400%. Moreover, for the first time, exponential increase of the catalytic rate was evidenced during galvanostatic transient experiment in excellent agreement with EPOC equation.

  2. The Development of Environmental Barrier Coatings for SiCSiC Ceramic Matrix Composites: Challenges and Opportunities

    Science.gov (United States)

    Zhu, Dongming

    2014-01-01

    Environmental barrier coatings (EBCs) and SiC/SiC ceramic matrix composites (CMCs) systems will play a crucial role in future turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. The development of prime-reliant environmental barrier coatings is a key to enable the applications of the envisioned CMC components to help achieve next generation engine performance and durability goals. This paper will primarily address the performance requirements and design considerations of environmental barrier coatings for turbine engine applications. The emphasis is placed on current candidate environmental barrier coating systems for SiCSiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. Major technical barriers in developing advanced environmental barrier coating systems, the coating integrations with next generation CMC turbine components having improved environmental stability, cyclic durability and system performance will be described. The development trends for turbine environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling will be discussed.

  3. Microstructure Evolution and Durability of Advanced Environmental Barrier Coating Systems for SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Evans, Laura J.; McCue, Terry R.; Harder, Bryan

    2016-01-01

    Environmental barrier coated SiC-SiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures with improved efficiency, reduce engine weight and cooling requirements. Advanced HfO2 and rare earth silicate environmental barrier coatings (EBCs), along with multicomponent hafnium and rare earth silicide EBC bond coats have been developed. The coating degradation mechanisms in the laboratory simulated engine thermal cycling, and fatigue-creep operating environments are also being investigated. This paper will focus on the microstructural and compositional evolutions of an advanced environmental barrier coating system on a SiC-SiC CMC substrate during the high temperature simulated durability tests, by using a Field Emission Gun Scanning Electron Microscopy, Energy Dispersive Spectroscopy (EDS) and Wavelength Dispersive Spectroscopy (WDS). The effects of Calcium-Magnesium-Alumino-Silicate (CMAS) from road sand or volcano-ash deposits on the degradation mechanisms of the environmental barrier coating systems will also be discussed. The detailed analysis results help understand the EBC-CMC system performance, aiming at the durability improvements to achieve more robust, prime-reliant environmental barrier coatings.

  4. 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.

  5. Ceramic membrane by tape casting and sol-gel coating for microfiltration and ultrafiltration application

    Science.gov (United States)

    Das, Nandini; Maiti, H. S.

    2009-11-01

    Alumina membrane filters in the form of thin (0.3-0.8 mm) discs of 25-30 mm diameter suitable for microfiltration application have been fabricated by tape-casting technique. Further using this microfiltration membrane as substrate, boehmite sol coating was applied on it and ultrafiltration membrane with very small thickness was formed. The pore size of the microfiltration membrane could be varied in the range of 0.1-0.7 μm through optimisation of experimental parameter. In addition, each membrane shows a very narrow pore size distribution. The most important factor, which determines the pore size of the membrane, is the initial particle size and its distribution of the ceramic powder. The top thin ultrafiltration, boehmite layer was prepared by sol-gel method, with a thickness of 0.5 μm. Particle size of the sol was approximately 30-40 nm. The structure and formation of the layer was analysed through TEM. At 550 °C formation of the top layer was completed. The pore size of the ultrafiltration membrane measured from TEM micrograph was almost 10 nm. Results of microbial (Escherichia coli—smallest-sized water-borne bacteria) test confirm the possibility of separation through this membrane

  6. Microstructure and Properties of Al2O3 Matrix Ceramic Coating Prepared by Thermo Chemical Reaction%热化学反应法制备Al2O3基陶瓷涂层的组织与性能

    Institute of Scientific and Technical Information of China (English)

    张媛; 周小飞

    2016-01-01

    The protective Al2O3 matrix ceramic coatings on the surface of 1Cr18Ni9 steel are prepared by thermo chemical reaction.The micro morphology,composition and structure of the combination layers were studied using SEM and EDS microanalysis instrument,and the corrosion resistance of the coating was tested by immersion corrosion experiments.The results show that the coating is dense and uniform,and there are chemical reaction between the ceramic coating and the matrix.And the existence of ceramic coating can effectively improve the corrosion resistance of 1Cr18Ni9 steel in acid and alkali.%采用热化学法在1Cr 18Ni9钢表面制备Al2O3基陶瓷涂层,利用SEM、EDS等微观分析仪器研究了结合层的微观形貌、成分及组织结构,利用浸泡腐蚀实验检测了涂层的耐蚀性.结果表明,涂层致密均匀,与基体发生了化学反应,陶瓷涂层的存在有效的提高了1Cr18Ni9钢的抗酸、碱腐蚀能力.

  7. Ceramic composite separators coated with moisturized ZrO(2) nanoparticles for improving the electrochemical performance and thermal stability of lithium ion batteries.

    Science.gov (United States)

    Kim, Ki Jae; Kwon, Hyuk Kwon; Park, Min-Sik; Yim, Taeeun; Yu, Ji-Sang; Kim, Young-Jun

    2014-05-28

    We introduce a ceramic composite separator prepared by coating moisturized ZrO2 nanoparticles with a poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-12wt%HFP) copolymer on a polyethylene separator. The effect of moisturized ZrO2 nanoparticles on the morphology and the microstructure of the polymeric coating layer is investigated. A large number of micropores formed around the embedded ZrO2 nanoparticles in the coating layer as a result of the phase inversion caused by the adsorbed moisture. The formation of micropores highly affects the ionic conductivity and electrolyte uptake of the ceramic composite separator and, by extension, the rate discharge properties of lithium ion batteries. In particular, thermal stability of the ceramic composite separators coated with the highly moisturized ZrO2 nanoparticles (a moisture content of 16 000 ppm) is dramatically improved without any degradation in electrochemical performance compared to the performance of pristine polyethylene separators.

  8. Development Status and Performance Comparisons of Environmental Barrier Coating Systems for SiCSiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Harder, Bryan

    2016-01-01

    Environmental barrier coatings (EBC) and SiCSiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft turbine engine systems, because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. This paper presents current NASA EBC-CMC development emphases including: the coating composition and processing improvements, laser high heat flux-thermal gradient thermo-mechanical fatigue - environmental testing methodology development, and property evaluations for next generation EBC-CMC systems. EBCs processed with various deposition techniques including Plasma Spray, Electron Beam - Physical Vapor Deposition, and Plasma Spray Physical Vapor Deposition (PS-PVD) will be particularly discussed. The testing results and demonstrations of advanced EBCs-CMCs in complex simulated engine thermal gradient cyclic fatigue, oxidizing-steam and CMAS environments will help provide insights into the coating development strategies to meet long-term engine component durability goals.

  9. New chemical approach to obtain dense layer phosphate-based ionic conductor coating on negative electrode material surface: Synthesis way, outgassing and improvement of C-rate capability

    Science.gov (United States)

    Fleutot, Benoit; Davoisne, Carine; Gachot, Grégory; Cavalaglio, Sébastien; Grugeon, Sylvie; Viallet, Virginie

    2017-04-01

    Li4Ti5O12 (LTO) based batteries have severe gassing behavior during charge/discharge and storage process, due to interfacial reactions between active material and electrolyte solution. In the same time, the electronic and ionic conductivity of pristine LTO is very poor and induces the use of nanoparticles which increase the outgassing phenomena. The coating of LTO particles could be a solution. For this the LTO spinel particles are modified with ionic conductor Li3PO4 coating using a spray-drying method. For the first time a homogeneous thin dense layer phosphate based conductor is obtained without nanoparticles, as a thin film material. It is so possible to study the influence of ionic conductor deposited on the negative electrode material on performances by the controlled layer thickness. This coating was characterized by XRD, SEM, XPS and TEM. The electrochemical performance of Li3PO4 coated Li4Ti5O12 is improved at high C-rate by the surface modification (improvement of 30 mAh g-1 at 5 C-rate compared to pristine LTO for 5 nm of coating), inducing by a modification of surface energy. An optimum coating thickness was studied. This type of coating allows a significant decrease of outgassing phenomena due the conformal coating and opens the way to a great number of studies and new technologies.

  10. Pyrochlore free 0.67PMN-0.33PT ceramics prepared by particle-coating method

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Ruiqing; Li, Yan [College of Materials Science and Engineering, Liaocheng University, Liaocheng 252059 (China); Gong, Shuwen [College of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059 (China); Liu, Yong [College of Materials Science and Engineering, Liaocheng University, Liaocheng 252059 (China); Li, Guorong [The State Key Lab of High Performance Ceramics and Superfinemicrostructure, Shanghai Institute of Ceramics, Chinese Academy of Science, Shanghai 200050 (China); Xu, Zhijun, E-mail: zhjxu@lcu.edu.cn [College of Materials Science and Engineering, Liaocheng University, Liaocheng 252059 (China)

    2012-08-20

    Highlights: Black-Right-Pointing-Pointer Pyrochlore-free PMN-PT powders were obtained by two-step particle-coating method. Black-Right-Pointing-Pointer Mg-citric acid polymeric complex coatings avoid the formation of pyrochlore phase. Black-Right-Pointing-Pointer Pyrochlore-free PMN-PT powders have been successfully prepared at 800 Degree-Sign C. Black-Right-Pointing-Pointer The PMN-PT ceramics sintered at 1150 Degree-Sign C exhibited excellent electrical properties. - Abstract: In present study, pyrochlore-free 0.67Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.33PbTiO{sub 3} (0.67PMN-0.33PT) powders and ceramics have been successfully prepared. Using oxides as raw materials, pyrochlore-free 0.67PMN-0.33PT powders were obtained by two-step particle-coating method. The XRD and EDS results confirmed that the Mg-citric acid polymeric complex coatings effectively prevent the direct contact between PbO and Nb{sub 2}O{sub 5} and thus avoid the formation of pyrochlore phase. The obtained pyrochlore-free 0.67PMN-0.33PT powders at 800 Degree-Sign C showed uniform and even grain size. The 0.67PMN-0.33PT ceramics sintered at 1150 Degree-Sign C for 2 h exhibited 99% of relative density and a piezoelectric coefficient (d{sub 33}) of 576pC/N, a remnant polarization (P{sub r}) of 28.4 {mu}C/cm{sup 2}, a planar electromechanical coupling factor (k{sub p}) of 0.55 and a mechanical quality factor (Q{sub m}) of 90.

  11. Influence of electrolyte temperature on properties and infrared emissivity of MAO ceramic coating on 6061 aluminum alloy

    Science.gov (United States)

    Al Bosta, Mohannad M. S.; Ma, Kung-Jeng

    2014-11-01

    6061 aluminum alloy was treated by MAO at various temperatures of the alkali silicate electrolyte using pulsed bipolar current mode for ten minutes. The surface microstructures and properties were studied using SEM, EDX, and XRD. The infrared emissivities of the MAO ceramic coatings were measured at the 70 °C using FTIR spectrometer. The electrolyte temperature strongly affected all the surface properties. The MAO alumina ceramics prepared in cold electrolytes have volcano-like and accumulated particles microstructures, while those prepared in hot electrolytes were: rougher, thinner and contained grainy spherical hollow bulgy microstructures with more pore density and more sillimanite and cristobalite phases which enhanced the IR emissivity. Also, the increment of sillimanite and cristobalite phases moved the apparent peaks toward longer wavelengths, and broadened the opaque region of the IR spectra. As a result, the increment of electrolyte temperature from 12.3 °C to 90.5 °C increased the average of LWIR emissivity from 80.4% to 94.4%, respectively, for the MAO ceramic coatings.

  12. Durability and CMAS Resistance of Advanced Environmental Barrier Coatings Systems for SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming

    2015-01-01

    Environmental barrier coatings (EBCs) and SiCSiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures with improved efficiency, reduce engine weight and cooling requirements. This paper will emphasize advanced environmental barrier coating developments for SiCSiC turbine airfoil components, by using advanced coating compositions and processing, in conjunction with mechanical and environment testing and durability validations. The coating-CMC degradations and durability in the laboratory simulated engine fatigue-creep and complex operating environments are being addressed. The effects of Calcium-Magnesium-Alumino-Silicate (CMAS) from road sand or volcano-ash deposits on the degradation mechanisms of the environmental barrier coating systems will be discussed. The results help understand the advanced EBC-CMC system performance, aiming at the durability improvements of more robust, prime-reliant environmental barrier coatings for successful applications of the component technologies and lifing methodologies.

  13. Effects Of Polylactic Acid Coating and Compression Load on the Delivery of Protein and Steroid from HA Ceramic Devices.

    Science.gov (United States)

    Benghuzzi, Hamed; Tucci, Michelle A; Ibrahim, Jamil

    2015-01-01

    Density variations, due to particle size and time and temperature of sintering, affect the delivery profile of substances from ceramic delivery devices. This investigation was conducted to study the effect of polylactic acid (PLA) impregnation on the porosity of hydroxyapatite (HA) capsules by studying the delivery rate of bovine serum albumin (BSA) and testosterone (TE). HA capsules were fabricated by cold compressing calcined particles at 1000, 3000, and 5000 lbs. Each group was subdivided into PLA-impregnated and non-PLA impregnated capsules. Each capsule was loaded with either 40 mg of TE (impregnated or nonimpregnated with PLA polymer) or BSA. Data obtained in this study suggest that: (1) PLA impregnation of HA ceramic capsules decreases the rate of release of drugs from the ceramic reservoir, (2) Physiochemical characteristics of the drugs to be delivered is an instrumental key in the sustained release profiles, (3) Compression load of HA reservoirs is a key factor in predicting the duration and level of sustained delivery, and (4) Polymer coating of HA ceramic capsules reduces the pore size, as well as, blocking some of the pores on the surface.

  14. Experimental and analytical study of ceramic-coated turbine-tip shroud seals for small turbine engines

    Science.gov (United States)

    Biesiadny, T. J.; Mcdonald, G. E.; Hendricks, R. C.; Little, J. K.; Robinson, R. A.; Klann, G. A.; Lassow, E. S.

    1985-01-01

    The results of an experimental and analytical evaluation of ceramic turbine tip shrouds within a small turbine engine operating environment are presented. The ceramic shrouds were subjected to 1001 cycles between idle and high power and steady-state conditions for a total of 57.8 engine hr. Posttest engine inspection revealed mud-flat surface cracking, which was attributed to microcracking under tension with crack penetration to the ceramic and bond coat interface. Sections and micrographs tend to corroborate the thesis. The engine test data provided input to a thermomechanical analysis to predict temperature and stress profiles throughout the ceramic gas-path seal. The analysis predicts cyclic thermal stresses large enough to cause the seal to fail. These stresses are, however, mitigated by inelastic behavior of the shroud materials and by the microfracturing that tensile stresses produce. Microfracturing enhances shroud longevity during early life but provides the failure mechanism during life but provides the failure mechanism during extended life when coupled with the time dependent inelastic materials effects.

  15. Applicability assessment of ceramic microbeads coated with hydroxyapatite-binding silver/titanium dioxide ceramic composite earthplus™ to the eradication of Legionella in rainwater storage tanks for household use.

    Science.gov (United States)

    Oana, Kozue; Kobayashi, Michiko; Yamaki, Dai; Sakurada, Tsukasa; Nagano, Noriyuki; Kawakami, Yoshiyuki

    2015-01-01

    Water environments appear to be the habitats of Legionella species. Legionellosis is considered as a preventable illness because bacterial reservoirs can be controlled and removed. Roof-harvested rainwater has attracted significant attention not only as a groundwater recharge but also as a potential alternative source of nonpotable water. We successfully developed ceramic microbeads coated with hydroxyapatite-binding silver/titanium dioxide ceramic composite earthplus™ using the thermal spraying method. The ceramic microbeads were demonstrated to have bactericidal activities against not only Legionella but also coliform and heterotrophic bacteria. Immersing the ceramic microbeads in household rainwater storage tanks was demonstrated to yield the favorable eradication of Legionella organisms. Not only rapid-acting but also long-lasting bactericidal activities of the ceramic microbead were exhibited against Legionella pneumophila. However, time-dependent attenuation of the bactericidal activities against Legionella were also noted in the sustainability appraisal experiment. Therefore, the problems to be overcome surely remain in constantly managing the Legionella-pollution by means of immersing the ceramic microbeads. The results of our investigation apparently indicate that the earthplus™-coated ceramic microbeads would become the favorable tool for Legionella measures in household rainwater storage tanks, which may become the natural reservoir for Legionella species. Our investigation would justify further research and data collection to obtain more reliable procedures to microbiologically regulate the Legionella in rainwater storage tanks.

  16. Structure and corrosion resistance of ZrO{sub 2} ceramic coatings on AZ91D Mg alloys by plasma electrolytic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Yao Zhongping, E-mail: yaozhongping@hit.edu.cn [School of Chemical Engineering and Technology, Harbin Institute of Technology Harbin 150001 (China); Postdoctoral Station of Chemistry Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Xu Yongjun; Liu Yunfu; Wang Dali; Jiang Zhaohua; Wang Fuping [School of Chemical Engineering and Technology, Harbin Institute of Technology Harbin 150001 (China)

    2011-08-18

    Highlights: > The ZrO{sub 2} ceramic coatings on AZ91D Mg alloys was prepared in tripolyphosphate and fluorozirconate solution. > The double-layer structure with the loose and porous outer layer and the compact inner layer was analyzed by SEM and EIS technique > The polarization resistance obtained from the equivalent circuit of the EIS was consistent with the results of the polarizing curves tests. - Abstract: The aim of this work is to study the structure and the corrosion resistance of the plasma electrolytic oxidation ZrO{sub 2} ceramic coatings on Mg alloys. The ceramic coatings were prepared on AZ91D Mg alloy in Na{sub 5}P{sub 3}O{sub 10} and K{sub 2}ZrF{sub 6} solution by pulsed single-polar plasma electrolytic oxidation (PEO). The phase composition, morphology and element distribution in the coating were investigated by X-ray diffractometry, scanning electron microscopy and energy distribution spectroscopy, respectively. The results show that the coating thickness and surface roughness were increased with the increase of the reaction time. The ceramic coatings were of double-layer structure with the loose and porous outer layer and the compact inner layer. And the coating was composed of P, Zr, Mg and K, of which P and Zr were the main elements in the coating. P in the coating existed in the form of amorphous state, while Zr crystallized in the form of t-ZrO{sub 2} and a little c-ZrO{sub 2} in the coating. Electrochemical impedance spectra (EIS) and the polarizing curve tests of the coatings were measured through CHI604 electrochemical analyzer in 3.5% NaCl solution to evaluate the corrosion resistance. The polarization resistance obtained from the equivalent circuit of the EIS was consistent with the results of the polarizing curves tests.

  17. Characterization of photocatalytically active coatings based on TiO2/Zn-Al layered double hydroxide on ceramic tiles

    Directory of Open Access Journals (Sweden)

    Vulić Tatjana J.

    2013-01-01

    Full Text Available The self-cleaning function (photocatalytic activity and surface hydrophilicity/hydrophobicity is of great importance for ceramic tiles from both economic and environmental point of view. This research is focused on the preparation of suitable photocatalytic suspensions studying the influence of the photocatalyst powder amount and the molecular mass of polyethylene glycol (PEG on the self-cleaning properties of the suspensions deposited on the ceramic tile surface. Photocatalysts based on Zn-Al double layered hydroxides with TiO2 as active component, were synthesized and used for the preparation of the suspensions. The coated tiles prepared using smaller photocatalyst amount and the highest investigated molecular mass of PEG (PEG 4000 showed the highest photocatalytic activity in the Rhodamine B degradation reaction, as well as the appropriate surface properties. [Projekat Ministarstva nauke Republike Srbije, br. III45008

  18. Survival of Staphylococcus aureus exposed to UV radiation on the surface of ceramic tiles coated with TiO2.

    Science.gov (United States)

    Szczawiński, J; Tomaszewski, H; Jackowska-Tracz, A; Szczawińska, M E

    2011-01-01

    The aim of this study was to determine and compare the antimicrobial activity of UV radiation of wavelength 253.7 nm (used in typical germicidal lamps) against Staphylococcus aureus on the surfaces of conventionally produced white ceramic wall tiles (matt and shiny) and the same tiles coated with TiO2 using three different methods: RF diode sputtering, atmospheric pressure chemical vapour deposition (APCVD) and spray pyrolysis deposition (SPD). Results clearly indicate that the bactericidal action of UV radiation is much stronger on the surfaces of tiles coated with TiO2 than on the tiles uncovered. The strongest bactericidal effect of UV radiation was found for film prepared by APCVD. Results of experiments for shiny and matt tiles did not differ statistically. The use of ceramic wall tiles coated with TiO2 films in hospitals, veterinary clinics, laboratories, food processing plants and other places where UV radiation is applied for disinfection should greatly improve the efficiency of this treatment.

  19. Fabrication of ceramic oxide-coated SWNT composites by sol-gel process with a polymer glue

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Cheng; Gao Lei; Chen Yongming, E-mail: ymchen@iccas.ac.cn [Institute of Chemistry, Chinese Academy of Sciences, Laboratory of Polymer Physics and Chemistry (China)

    2011-09-15

    The functional copolymer bearing alkoxysilyl and pyrene groups, poly[3-(triethoxysilyl)propyl methacrylate]-co-[(1-pyrene-methyl) methacrylate] (TEPM{sub 13}-co-PyMMA{sub 3}), was synthesized via atom transfer radical polymerization. Attributing the {pi}-{pi} interaction of pyrene units with the walls of single-walled carbon nanotubes (SWNTs), this polymer could disperse and exfoliate SWNTs in different solvents through physical interaction as demonstrated by TEM, UV/Vis absorption, and FT-IR analysis. The alkoxysilyl groups functionalized SWNTs were reacted with different inorganic precursors via sol-gel reaction, and, as a results, silica, titania, and alumina were coated onto the surface of SWNTs, respectively via copolymers as a molecular glue. The nanocomposites of ceramic oxides/SWNTs were characterized by SEM analysis. Dependent upon the feed, the thickness of inorganic coating can be tuned easily. This study supplies a facile and general way to coat SWNTs with ceramic oxides without deteriorating the properties of pristine SWNTs.

  20. Rare earth oxide reinforced Al{sub 2}O{sub 3}-TiO{sub 2} ceramics for inert coating of metallic parts for petroleum extraction

    Energy Technology Data Exchange (ETDEWEB)

    Yadava, Yoggendra Prasad; Rego, Sheila Alves Bezerra da Costa; Ferreira, Ricardo Artur Sanguinetti [Universidade Federal de Pernambuco (UFPE), Recife (Brazil)

    2012-07-01

    Recent findings of largest known pre-salt petroleum reservoir in Brazil have created an intense demand for new materials capable of withstanding direct contact with the crude petroleum as it is a highly corrosive and chemically reactive fluid. Petroleum drilling equipment, storage tanks and transportation systems suffer from constant physical stress caused by chemical attack of crude petroleum on its structure. Ceramics are materials with high chemical stability in hostile environment and therefore can be used as an inert coating material to resolve such problems. To date, ceramics based on alumina are most widely used in practice where there is demand for high mechanical strength and high fracture toughness. However intrinsic fragility of ceramics is still a fatal factor for their use in mechanical structures. To improve these characteristics, usually ceramics are reinforced with one or more ceramic additives. Mechanical properties of alumina based ceramics improve considerably with the addition of TiO{sub 2}, TiN, ZrO{sub 2} etc. ceramic additives. Nucleation and propagation of cracks is a major problem for ceramic coating applications. Initial studies show that addition of small percentages of rare earth oxides can increase the toughness of the alumina based ceramics. In the present work, we have produced rare-earth oxide (CeO{sub 2}) reinforced Al{sub 2}O{sub 3}-TiO{sub 2} ceramics in proportions of 5-20 wt% TiO{sub 2} and 2%wt% CeO{sub 2} through thermomechanical processing and sintering techniques and studied there microstructural characteristics and mechanical properties. To evaluate the potential of these ceramics as inert coatings for crude petroleum extraction, storage and transportation systems, we have studied the physic-chemical and mechanical stability of these ceramics in crude petroleum environment. Our studies presented satisfactory results in terms of physic-chemical and mechanical stability of these materials for the use of 2wt% of CeO{sub 2

  1. Microstructure and Mechanical Properties of Alumina Powder Coatings by a New Multi-Chamber Detonation Sprayer

    Science.gov (United States)

    Prozorova, M. S.; Kovaleva, M. G.; Arseenko, M. Yu.; Yapryntsev, M. N.; Tyurin, Yu. N.; Kolisnichenko, O. V.; Vasilik, N. Ya.; Sirota, V. V.; Pavlenko, I. A.; Mamunin, K. N.

    2016-11-01

    The dense ceramic coatings based on alumina with hardness of 1100±25 HV0.3 and porosity of less than 1% have been prepared by multi-chamber detonation sprayer (MCDS) with a barrel length of 500mm. The intermetallic compound of type FeAl was revealed in the area of the coating that adjoins the substrate.

  2. Advanced thermal barrier coating systems

    Science.gov (United States)

    Dorfman, M. R.; Reardon, J. D.

    1985-01-01

    Current state-of-the-art thermal barrier coating (TBC) systems consist of partially stabilized zirconia coatings plasma sprayed over a MCrAlY bond coat. Although these systems have excellent thermal shock properties, they have shown themselves to be deficient for a number of diesel and aircraft applications. Two ternary ceramic plasma coatings are discussed with respect to their possible use in TBC systems. Zirconia-ceria-yttria (ZCY) coatings were developed with low thermal conductivities, good thermal shock resistance and improved resistance to vanadium containing environments, when compared to the baseline yttria stabilized zirconia (YSZ) coatings. In addition, dense zirconia-titania-yttria (ZTY) coatings were developed with particle erosion resistance exceeding conventional stabilized zirconia coatings. Both coatings were evaluated in conjunction with a NiCr-Al-Co-Y2O3 bond coat. Also, multilayer or hybrid coatings consisting of the bond coat with subsequent coatings of zirconia-ceria-yttria and zirconia-titania-yttria were evaluated. These coatings combine the enhanced performance characteristics of ZCY with the improved erosion resistance of ZTY coatings. Improvement in the erosion resistance of the TBC system should result in a more consistent delta T gradient during service. Economically, this may also translate into increased component life simply because the coating lasts longer.

  3. Development of Advanced Environmental Barrier Coatings for SiC/SiC Ceramic Matrix Composites: Path Toward 2700 F Temperature Capability and Beyond

    Science.gov (United States)

    Zhu, Dongming; Harder, Bryan; Hurst, Janet B.; Good, Brian; Costa, Gustavo; Bhatt, Ramakrishna T.; Fox, Dennis S.

    2017-01-01

    Advanced environmental barrier coating systems for SiC-SiC Ceramic Matrix Composite (CMC) turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant coating development challenges is to achieve prime-reliant environmental barrier coating systems to meet the future 2700F EBC-CMC temperature stability and environmental durability requirements. This presentation will emphasize recent NASA environmental barrier coating system testing and down-selects, particularly the development path and properties towards 2700-3000F durability goals by using NASA hafnium-hafnia-rare earth-silicon-silicate composition EBC systems for the SiC-SiC CMC turbine component applications. Advanced hafnium-based compositions for enabling next generation EBC and CMCs capabilities towards ultra-high temperature ceramic coating systems will also be briefly mentioned.

  4. Effect of silica coating combined to a MDP-based primer on the resin bond to Y-TZP ceramic.

    Science.gov (United States)

    May, Liliana Gressler; Passos, Sheila Pestana; Capelli, Diana Barca; Ozcan, Mutlu; Bottino, Marco Antonio; Valandro, Luiz Felipe

    2010-10-01

    The aim of this study was to evaluate the influence of silica coating and 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-based primer applications upon the bonding durability of a MDP-based resin cement to a yttrium stabilized tetragonal zirconia (Y-TZP) ceramic. Ninety-six Y-TZP tabs were embedded in an acrylic resin (free surface for adhesion: 5 × 5 mm(2)), ground finished and randomly divided into four groups (N = 24) according to the ceramic surface conditioning: (1) cleaning with isopropanol (ALC); (2) ALC + phosphoric acid etching + MDP-based primer application (MDP-primer); (3) silica coating + 3-methacryloyloxypropyl trimethoxysilane (MPS)-based coupling agent application (SiO2 + MPS-Sil); and (4) SiO2 + MDP-primer. The MDP-based resin cement was applied on the treated surface using a cylindrical mold (diameter= 3 mm). Half of the specimens from each surface conditioning were stored in distilled water (37 °C, 24 h) before testing. Another half of the specimens were stored (90 days) and thermo-cycled (12,000 x) during this period (90 d/TC) before testing. A shear bond strength (SBS) test was performed at a crosshead speed of 0.5 mm/min. Two factors composed the experimental design: ceramic conditioning strategy (in four levels) and storage condition (in two levels), totaling eight groups. After 90 d/TC (Tukey; p MDP-primer (24.40 MPa) promoted the highest SBS. The ALC and MDP-primer groups debonded spontaneously during 90 d/TC. Bonding values were higher and more stable in the SiO2 groups. The use of MDP-primer after silica coating increased the bond strength.

  5. Study of surface roughness and flank wear in hard turning of AISI 4140 steel with coated ceramic inserts

    Energy Technology Data Exchange (ETDEWEB)

    Das, Sudhansu Ranjan; Kuma, Amaresh [National Institute of Technology, Jamshedpur (India); Dhupal, Debabrata [Veer Surendra Sai University of Technology, Burla (India)

    2015-10-15

    This experimental investigation deals with dry hard turning of AISI 4140 steel using PVD-TiN coated Al{sub 2}O{sub 3}+TiCN mixed ceramic inserts. The combined effect of cutting parameters (cutting speed, feed and depth of cut) on performance characteristics such as surface roughness and flank wear is explored by Full factorial design (FFD) and analysis of variance (ANOVA). The results show that feed is the principal cutting parameter influencing surface roughness, followed by cutting speed. However, flank wear is affected by the cutting speed and interaction of feed-depth of cut, although depth of cut has not been found statistically significant, but flank wear is an increasing function of depth of cut. Observations are made on the machined surface, and worn tool by Scanning electron microscope (SEM) to establish the process. Abrasion was the major wear mechanism found during hard turning within the studied range. The effect of tool wear on surface roughness was also studied. The experimental data were analyzed to predict the optimal range of surface roughness and flank wear. Based on Response surface methodology (RSM), mathematical models were developed for surface roughness (Ra) and flank wear (VB) with 95% confidence level. Finally, under optimum cutting conditions (obtained by response optimization technique), tool life was evaluated to perform cost analysis for justifying the economic viability of coated ceramic inserts in hard turning. The estimated machining cost per part for TiN coated ceramic was found to be lower (Rs. 12.31) because of higher tool life (51 min), which results in the reduction of downtime and increase in savings.

  6. Improvement of anti-oxidation properties of carbon fibers by SiC/SiO2 ceramic coating.

    Science.gov (United States)

    Kim, Bo-Hye; Yang, Kap Seung; Woo, Hee-Gweon; Kim, Su Yeun

    2011-08-01

    To improve the anti-oxidation properties of carbon fibers (CFs), the sol-gel method followed by pyrolysis was used to coat CFs with SiC/SiO2 ceramic coatings. The SiO2 sol-gel coating was performed by dip coating a PAN(polyacrylonitrile)-based stabilized fiber (PSF) in a silica sol prepared by the polycondensation of tetraethylorthosilicate (TEOS) in the presence of an acidic catalyst. The PSF coated with SiO2 sol then underwent heat treatments at high temperatures in an inert atmosphere to deposit the SiC/SiO2 and carbonize the deposited fibers. The surface morphology of the CFs deposited with SiC/SiO2 was characterized using a scanning electron microscope (SEM). The relative oxidation resistance of the SiC/SiO2 layer deposited on the CFs was determined by the weight loss due to the use of a thermogravimetric analyzer (TGA) under flowing air, and the data were used to calculate the activation energies through an Arrhenius plot.

  7. Bonding mechanism and performance of ceramic coatings by sol-gel process

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Thin alumina coatings were prepared on carbide tools to enhance their wear-resistant ability by dip coating from an aluminum alkoxide solution. The coating eventually obtained was perfectly integrated, without any macroscopic defect, and showed good performance in turning medium carbon steel, which presented a novel and promising coating method for cutting tools. The coating morphology before and after heat treatment was examined with the aid of a scanning electron microscope (SEM). The composition of coating and interface layer as well as the crystal structure of coating was characterized by X-ray diffraction (XRD). The elemental distribution near the interlayer was analyzed by electron probe microanalysis (EPMA).

  8. Applicability assessment of ceramic microbeads coated with hydroxyapatite-binding silver/titanium dioxide ceramic composite earthplus™ to the eradication of Legionella in rainwater storage tanks for household use

    Directory of Open Access Journals (Sweden)

    Oana K

    2015-08-01

    Full Text Available Kozue Oana,1,2 Michiko Kobayashi,1 Dai Yamaki,3 Tsukasa Sakurada,3 Noriyuki Nagano,1,2 Yoshiyuki Kawakami1,2 1Division of Infection Control and Microbiological Regulation, Department of Health and Medical Sciences, Shinshu University Graduate School of Medicine, 2Division of Clinical Microbiology, Department of Biomedical Laboratory Sciences, School of Health Sciences, Shinshu University School of Medicine, Matsumoto, 3Shinshu Ceramics Co., Ltd., Kiso, Nagano, Japan Abstract: Water environments appear to be the habitats of Legionella species. Legionellosis is considered as a preventable illness because bacterial reservoirs can be controlled and removed. Roof-harvested rainwater has attracted significant attention not only as a groundwater recharge but also as a potential alternative source of nonpotable water. We successfully developed ceramic microbeads coated with hydroxyapatite-binding silver/titanium dioxide ceramic composite earthplus™ using the thermal spraying method. The ceramic microbeads were demonstrated to have bactericidal activities against not only Legionella but also coliform and heterotrophic bacteria. Immersing the ceramic microbeads in household rainwater storage tanks was demonstrated to yield the favorable eradication of Legionella organisms. Not only rapid-acting but also long-lasting bactericidal activities of the ceramic microbead were exhibited against Legionella pneumophila. However, time-dependent attenuation of the bactericidal activities against Legionella were also noted in the sustainability appraisal experiment. Therefore, the problems to be overcome surely remain in constantly managing the Legionella-pollution by means of immersing the ceramic microbeads. The results of our investigation apparently indicate that the earthplus™-coated ceramic microbeads would become the favorable tool for Legionella measures in household rainwater storage tanks, which may become the natural reservoir for Legionella species

  9. Ceramic materials of low-temperature synthesis for dielectric coating applied by 3D aerosol printing used in nano- and microelectronics, lighting engineering, and spacecraft control devices

    Science.gov (United States)

    Ivanov, A. A.; Tuev, V. I.; Nisan, A. V.; Potapov, G. N.

    2016-11-01

    A synthesis technique of low-temperature ceramic material based on aluminosilicates of dendrimer morphology capable to contain up to 80 wt % of nitrides and oxides of high-melting compounds as filler has been developed. The synthesis is based on a sol-gel method followed by mechanochemical treatment and ultrasonic dispersing. Dielectric ceramic layers with the layer thickness in the nanometer range and high thermal conductivity have been obtained for the first time by 3D aerosol printing of the synthesized material. The study of the obtained ceramic coating on the metal surface (Al) has proved its use prospects in microelectronics, light engineering, and devices for special purposes.

  10. On the use, characterization and performance of silane coupling agents between organic coatings and metallic or ceramic substrates

    Science.gov (United States)

    van Ooij, W. J.; Zhang, B. C.; Conners, K. D.; Hörnström, S.-E.

    1996-01-01

    Examples are given of the use of organofunctional silane coupling agents for promoting bonding between organic coatings and metallic or ceramic (i.e. oxide) substrates. The orientation of the silane molecules and the type of bonding with the metal oxide can be determined successfully by Time-of-Flight SIMS. Oriented films of aminosilanes are demonstrated to be unstable in air. A prerinse with an inorganic silicate is introduced as a suitable method for masking the ubiquitous carbonaceous contamination at the metal surface, thus promoting the proper orientation and covalent bonding. Some practical applications are described, such as the pretreatment of Galvalume■ surfaces as a replacement of existing chromate treatments in coil coating applications. Electrochemical Impedance Spectroscopy (EIS) is shown to be a powerful tool for studying the performance of the silane treatment under a paint.

  11. Preparation and Application of Ceramic Coating on Magnesium Alloy%镁合金陶瓷涂层制备工艺及应用

    Institute of Scientific and Technical Information of China (English)

    赵斌; 李欣棉; 陶莹; 李智超

    2012-01-01

    The characteristics and research status of preparation technology of ceramic coating on Mg alloy (including methods of thermochemical reaction, thermal spray and so on) were introduced, and the application prospect of ceramic coating on Mg alloy in the production practice was pointed out.%介绍了镁合金陶瓷涂层的制备工艺(包括热化学反应法、热喷涂法及其他方法)的特点及研究现状,并指岀了镁合金陶瓷涂层在生产实践中的应用前景.

  12. Frictional behaviors of some nitrogen ceramics in conformal contact with tin coated Al-Si alloy, steel and MMC

    Science.gov (United States)

    Wang, Q.; Cheng, H. S.; Fine, M. E.

    1994-07-01

    The frictional behavior of certain nitrogen-containing ceramics, such as silicon nitride, alpha sialons, and beta sialons as journal materials were studied in conformal contact with a tin-coated Al-Si alloy (Al-Si/Sn), forged 1141 steel and a cast aluminum matrix composite with silicon carbide reinforcement (cast metal matrix composites (MMC)) as bearing materials while lubricated with SAE 10W30. A case-hardened 1016 steel was also tested with the Al-Si/Sn and cast MMC bearings under the same conditions. The friction values of the ceramic and the steel journal wear pairs were compared and their frictional behaviors were evaluated. Silicon nitride and one of the beta sialons exhibited higher load-supporting capacities than the others when they were in contact with the 1141 steel bearings. The journal surface roughness was found to be very important when the journals were in contact with the Al-Si/Sn bearings. The frictional behavior of the ceramics and cast MMC pairs and the steel and cast MMC pairs were controlled by different wear machanisms, namely for the former, hard particle pull-out and matrix plowing, and for the latter, iron transfer from the journal to the cast MMC bearing surface.

  13. CuCr2O4 Spinel Ceramic Pigments Synthesized by Sol-Gel Self-Combustion Method for Solar Absorber Coatings

    Science.gov (United States)

    Ma, Pengjun; Geng, Qingfen; Gao, Xianghu; Yang, Shengrong; Liu, Gang

    2016-07-01

    A series of CuCr2O4 spinel ceramic pigments have been successfully synthesized via a facile and cost-effective sol-gel self-combustion method. The reaction mechanism was systematically studied using the corresponding characterization technologies. The results suggested that CuCr2O4 spinel ceramic pigments could be obtained at annealing temperature of 600 °C for 1 h, and the size, morphology, and crystallinity of CuCr2O4 spinel were greatly influenced by the annealing temperature. The as-burnt powder and CuCr2O4 spinel ceramic pigment were then employed to fabricate thickness sensitive spectrally selective (TSSS) paint coatings by a convenient spray-coating technique. The results revealed that spectral selectivity of TSSS paint coatings based on CuCr2O4 spinel ceramic pigments was much better than that of paint coatings based on the as-burnt powders. Furthermore, the effect of surface features of TSSS paint coatings on its optical property and hydrophobicity was investigated in detailed.

  14. Selective laser sintering of polymer-coated Al2O3/ZrO2/TiC ceramic powder

    Institute of Scientific and Technical Information of China (English)

    BAI Pei-kang; CHENG Jun; LIU Bin

    2005-01-01

    A type of polymer-coated Al2O3/ZrO2/TiC ceramic powder was prepared. The laser sintering mechanism of polymer-coated Al2 O3/ZrO2/TiC powder was investigated by studying the dynamic laser sintering process.It is found that the mechanism is viscous flow when the sintering temperature is between 80 ℃ and 120 ℃, and it is melting/solidification when the temperature is above 120 ℃. The process parameters of selective laser sintering were optimized by using ortho-design method. The results show that the optimal parameters include laser power of 14 W,scanning velocity of 1 400 mm/s, preheating temperature of 50 ℃ and powder depth of 0.15 mm. A two-step posttreatment process is adopted to improve the mechanical properties of laser sintered part, which includes polymer debinding and high temperature sintering. After vacuum sintering for 2 h at 1 650 ℃, the bending strength and fracture toughness of Al2O3/ZrO2/TiC ceramic part reach 358 Mpa and 6.9 Mpa · m1/2 , respectively.

  15. Effect of Al2O3 Ceramic Particles on Corrosion Behaviour and Tribological Properties of Nickel Composite Coatings

    Directory of Open Access Journals (Sweden)

    Nowak M.

    2016-03-01

    Full Text Available The paper presents a study on corrosion behaviour and tribological properties of nickel composite coatings deposited by electrochemical method on aluminium alloy from 2xxx series (AlCu4MgSi. The nickel composite coatings were produced in a Watts bath of the following chemical composition: NiSO4·7H2O 150 g/l, NiCl2·6H2O 30 g/l, H3BO3 30 g/l with the addition of saccharin in an amount of 2 g/l. As hard ceramic dispersed particles embedded in the coating, alumina (Al2O3 was used in an amount of 12,5; 25; 50 and 75 g/l. Coatings were produced using cathodic current density of 6 A/dm2, bath temperature of 60°C, pH 4, and the time 60 minutes. The electroplating bath was stirred with a mechanical stirrer (350 rpm.

  16. Theoretical prediction of energy release rate for interface crack initiation by thermal stress in environmental barrier coatings for ceramics

    Science.gov (United States)

    Kawai, E.; Umeno, Y.

    2017-05-01

    As weight reduction of turbines for aircraft engines is demanded to improve fuel consumption and curb emission of carbon dioxide, silicon carbide (SiC) fiber reinforced SiC matrix composites (SiC/SiC) are drawing enormous attention as high-pressure turbine materials. For preventing degradation of SiC/SiC, environmental barrier coatings (EBC) for ceramics are deposited on the composites. The purpose of this study is to establish theoretical guidelines for structural design which ensures the mechanical reliability of EBC. We conducted finite element method (FEM) analysis to calculate energy release rates (ERRs) for interface crack initiation due to thermal stress in EBC consisting of Si-based bond coat, Mullite and Ytterbium (Yb)-silicate layers on a SiC/SiC substrate. In the FEM analysis, the thickness of one EBC layer was changed from 25 μm to 200 μm while the thicknesses of the other layers were fixed at 25 μm, 50 μm and 100 μm. We compared ERRs obtained by the FEM analysis and a simple theory for interface crack in a single-layered structure where ERR is estimated as nominal strain energy in the coating layers multiplied by a constant factor (independent of layer thicknesses). We found that, unlike the case of single-layered structures, the multiplication factor is no longer a constant but is determined by the combination of consisting coating layer thicknesses.

  17. Development and characterization of Si{sub 3}N{sub 4} coated AlCrN ceramic cutting tool

    Energy Technology Data Exchange (ETDEWEB)

    Souza, J.V.C.; Nono, M.C.A.; Martins, G.V.; Machado, J.P.B., E-mail: vitor@las.inpe.br [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil); Silva, O.M.M. [Instituto de Aeronautica e Espacao (CTA/IAE/AMR), Sao Jose dos Campos, SP (Brazil). Centro Tecnico Aeroespacial; Pimenta, M. [Oerlikon Balzers R. Mealicos Ltda, Jundiai, SP (Brazil)

    2009-07-01

    Nowadays, silicon nitride based cutting tools are used to machine cast iron from the automotive industry and nickel superalloys from the aero industries. Advances in manufacturing technologies (increased cutting speeds, dry machining, etc.) induced the fast commercial growth of physical vapor deposition (PVD) coatings for cutting tools, in order to increase their life time. In this work, a new composition of the Si{sub 3}N{sub 4} ceramic cutting tool was developed, characterized and subsequently coated, using a PVD process, with aluminum chromium nitride (AlCrN). The Si{sub 3}N{sub 4} substrate properties were analyzed by XRD, AFM, hardness and fracture toughness. The AlCrN coating was analyzed by AFM, grazing incidence X-ray diffraction (GIXRD) and hardness. The results showed that this PVD coating could be formed homogeneously, without cracks and promoted a higher surface hardness to the insert and consequently it can produce a better wear resistance during its application on high speed machining. (author)

  18. Revestimentos cerâmicos utilizados como barreira térmica Ceramic coatings used as thermal barrier

    Directory of Open Access Journals (Sweden)

    J. P. Oliveira

    2013-03-01

    Full Text Available Neste trabalho procurou-se fazer uma introdução aos revestimentos de barreira térmica cerâmicos, em especial à utilização deste tipo de materiais na camada top coat, apresentando as suas propriedades fundamentais. Posteriormente apresentam-se os novos materiais que podem vir a substituir a zircónia parcialmente estabilizada com ítria, sendo este o material mais utilizado para desempenhar esta função. Neste trabalho, também se faz uma descrição sumária dos métodos de processamento de cada material que foram abordados neste trabalho. E por fim apresenta-se uma tabela com algumas das propriedades termo-físicas mais importantes para os materiais analisados.In this work we started by doing a introduction to the ceramic thermal barrier coatings, especially in the utilization of this kind of material as top coat by presenting its fundamental properties. After we present new materials that may replace zirconia partially stabilized with yttria (PSZ, being this last material the most used as top coat. In this work, we also make a brief description of the processing methods for each material analyzed in this article. Last we present a table when some of the most important thermal-physical properties of the materials studied.

  19. Understanding the Formation of Limited Interlamellar Bonding in Plasma Sprayed Ceramic Coatings Based on the Concept of Intrinsic Bonding Temperature

    Science.gov (United States)

    Yao, Shu-Wei; Tian, Jia-Jia; Li, Chang-Jiu; Yang, Guan-Jun; Li, Cheng-Xin

    2016-12-01

    Interlamellar bonding is an important factor controlling the mechanical, thermal and electrical properties of plasma sprayed ceramic coatings. In order to understand the formation of limited interlamellar bonding, a theoretical model is proposed based on the concept of the intrinsic bonding temperature. The numerical simulation of the interface temperature between a molten splat and underlying splats was performed for splats with uniform and non-uniform thickness, in order to reveal the conditions for the interlamellar bonding formation. The interlamellar bonding ratio was theoretically estimated based on the bonding forming conditions. The features of interlamellar bonding revealed by the simulation agree well with the experimental observations. The bonding ratio of plasma sprayed coatings is significantly influenced by the distribution of splat thickness. According to the distribution of Al2O3 splat thickness in the coating, the theoretical estimation of bonding ratio yielded a value of 0.41 for the plasma sprayed Al2O3 coating at the ambient atmosphere conditions, which is reasonably consistent with the observation value. Therefore, the limited interlamellar bonding can be reasonably explained based on the sufficient condition that the maximum interface temperature between a molten splat and underlying splats is larger than the intrinsic bonding temperature.

  20. Compound Ceramic Coatings on Ti-6Al-4V by Micro-Plasma Oxidation in NaAlO2 Solution

    Institute of Scientific and Technical Information of China (English)

    YAO Zhong-ping; JIANG Zhao-hua; XIN Shi-gang; SUN Xue-tong; WU Zhen-dong

    2004-01-01

    Micro-plasma oxidation (MPO) technique is a new technique by which compound ceramic coating can be grown in situ on Al, Ti, Mg and many other valve-metals. Compound ceramic coatings on Ti-6Al-4V alloy were prepared for different time by pulsed bi-polar MPO in NaAlO2 solution. The phase composition, morphology and the element distribution of the coatings were studied by XRD, SEM and JEOL SUPERPROBE 733 electric probe, respectively.Electrochemical Impedance Spectra (EIS) of the coatings were measured to study the structure character of the coatings.Through the proper EIS interpreting software, the "equivalent circuit" of the coatings was established, and the fitting values of equivalent element were calculated. The coating is mainly composed of Al2TiO5, α-Al2O3 and rutile TiO2. The content of Ti element in the coating is less than that of substrate; its distribution is relatively uniform, and Ti in the outer layer is less than that in the inner layer. The content of Al in the coating is more than that of substrate, and its distribution is not even: Al in the middle part is more than that on both sides of the coating; And the EIS analysis has illustrated the double-layer structure of the coatings, and the outside layer is loosen and the inner layer compact; with the increase of the oxidizing time,the surface roughness of the coatings, and the porosity of the outer layer of the coating are increased while the compactness of the inner layer of the coatings are improved.

  1. Compound Ceramic Coatings on Ti-6AI-4V by Micro-Plasma Oxidation in NaAlO2 Solution

    Institute of Scientific and Technical Information of China (English)

    YAOZhong-ping; JIANGZhao-hua; XINShi-gang; SUNXue-tong; WUZhen-dong

    2004-01-01

    Micro-plasma oxidation (MPO) technique is a new technique by which compound ceramic coating can be grown in situ on AI, Ti, Mg and many other valve-metals. Compound ceramic coatings on Ti-6Al-4V alloy were prepared for different time by pulsed bi-polar MPO in NaAlO2 solution. The phase composition, morphology and the element distribution of the coatings were studied by XRD, SEM and JEOL SUPERPROBE 733 electric probe, respectively. Electrochemical Impedance Spectra (EIS) of the coatings were measured to study the structure character of the coatings. Through the proper EIS interpreting software, the "equivalent circuit" of the coatings was established, and the fitting values of equivalent element were calculated. The coating is mainly composed of Al2TiO5, α-Al2O3 and futile TiO2. The content of Ti element in the coating is less than that of substrate; its distribution is relatively uniform, and Ti in the outer layer is less than that in the inner layer. The content of A1 in the coating is more than that of substrate, and its distribution is not even: Al in the middle part is more than that on both sides of the coating; And the EIS analysis has illustrated the double-layer structure of the coatings, and the outside layer is loosen and the inner layer compact; with the increase of the oxidizing time, the surface roughness of the coatings, and the porosity of the outer layer of the coating are increased while the compactness of the inner layer of the coatings are improved.

  2. Si3N4 ceramic cutting tool sintered with CeO2 and Al2O3 additives with AlCrN coating

    Directory of Open Access Journals (Sweden)

    José Vitor Candido Souza

    2011-12-01

    Full Text Available Ceramic cutting tools are showing a growing market perspective in terms of application on machining operations due to their high hardness, wear resistance, and machining without a cutting fluid, therefore are good candidates for cast iron and Nickel superalloys machining. The objective of the present paper was the development of Si3N4 based ceramic cutting insert, characterization of its physical and mechanical properties, and subsequent coating with AlCrN using a PVD method. The characterization of the coating was made using an optical profiler, XRD, AFM and microhardness tester. The results showed that the tool presented a fracture toughness of 6.43 MPa.m½ and hardness of 16 GPa. The hardness reached 31 GPa after coating. The machining tests showed a decrease on workpiece roughness when machining with coated insert, in comparison with the uncoated cutting tool. Probably this fact is related to hardness, roughness and topography of AlCrN.

  3. Characterization of Al{sub 2}O{sub 3} ceramic coatings on 6063 aluminum alloy prepared in borate electrolytes by micro-arc oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Li, H.X. [MOE Key Laboratory of Mechanical Manufacture and Automation, Zhejiang University of Technology, No. 6, Zhaohui District, Hangzhou 310014 (China); Rudnev, V.S. [Institute of Chemistry FEB RAS, Pr. 100 let Vladivostok, Vladivostok 690022 (Russian Federation); Zheng, X.H. [MOE Key Laboratory of Mechanical Manufacture and Automation, Zhejiang University of Technology, No. 6, Zhaohui District, Hangzhou 310014 (China); Yarovaya, T.P. [Institute of Chemistry FEB RAS, Pr. 100 let Vladivostok, Vladivostok 690022 (Russian Federation); Song, R.G. [MOE Key Laboratory of Mechanical Manufacture and Automation, Zhejiang University of Technology, No. 6, Zhaohui District, Hangzhou 310014 (China)], E-mail: songrg@zjut.edu.cn

    2008-08-25

    Al{sub 2}O{sub 3} ceramic coatings were directly prepared on 6063 aluminum alloy in borate electrolytes by micro-arc oxidation technique. The microstructure, phase composition, elemental distribution, and micro-hardness of Al{sub 2}O{sub 3} ceramic coatings were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and micro-hardness test. The fabricated samples were almost composed of {alpha}-Al{sub 2}O{sub 3} and {gamma}-Al{sub 2}O{sub 3}, also there existed pores and cracks on the surface of the coatings. Micro-hardness test shows that the prepared coatings are of high hardness, which can satisfy the requirements for the mechanical application.

  4. Metal Oxide Assisted Preparation of Core-Shell Beads with Dense Metal-Organic Framework Coatings for the Enhanced Extraction of Organic Pollutants.

    Science.gov (United States)

    Del Rio, Mateo; Palomino Cabello, Carlos; Gonzalez, Veronica; Maya, Fernando; Parra, Jose B; Cerdà, Victor; Turnes Palomino, Gemma

    2016-08-08

    Dense and homogeneous metal-organic framework (MOF) coatings on functional bead surfaces are easily prepared by using intermediate sacrificial metal oxide coatings containing the metal precursor of the MOF. Polystyrene (PS) beads are coated with a ZnO layer to give ZnO@PS core-shell beads. The ZnO@PS beads are reactive in the presence of 2-methylimidazole to transform part of the ZnO coating into a porous zeolitic imidazolate framework-8 (ZIF-8) external shell positioned above the internal ZnO precursor shell. The obtained ZIF-8@ZnO@PS beads can be easily packed in column format for flow-through applications, such as the solid-phase extraction of trace priority-listed environmental pollutants. The prepared material shows an excellent permeance to flow when packed as a column to give high enrichment factors, facile regeneration, and excellent reusability for the extraction of the pollutant bisphenol A. It also shows an outstanding performance for the simultaneous enrichment of mixtures of endocrine disrupting chemicals (bisphenol A, 4-tert-octylphenol and 4-n-nonylphenol), facilitating their analysis when present at very low levels (coatings.

  5. Tissue response to implanted ceramic-coated titanium alloys in rats.

    Science.gov (United States)

    Satomi, K; Akagawa, Y; Nikai, H; Tsuru, H

    1988-07-01

    In order to assess the tissue compatibility of the hybrid materials for the dental implant (hydroxyapatite, titanium oxide and titanium nitride coated titanium alloys), tissue response to these materials implanted in the rat subcutaneous tissue was histologically examined. Initial inflammatory response was less evident in titanium oxide coated and non-coated titanium alloys. All materials were encapsulated by thin fibrous connective tissues. The membrane thickness of hydroxyapatite coated titanium alloy was significantly higher than that of titanium nitride coated one. These results suggest that all materials possess favourable tissue compatibility and may encourage clinical use as the dental implant.

  6. Application of Pre-coated Microfiltration Ceramic Membrane with Powdered Activated Carbon for Natural Organic Matter Removal from Secondary Wastewater Effluent

    KAUST Repository

    Kurniasari, Novita

    2012-12-01

    Ceramic membranes offer more advantageous performances than conventional polymeric membranes. However, membrane fouling caused by Natural Organic Matters (NOM) contained in the feed water is still become a major problem for operational efficiency. A new method of ceramic membrane pre-coating with Powdered Activated Carbon (PAC), which allows extremely contact time for adsorbing aquatic contaminants, has been studied as a pre-treatment prior to ceramic microfiltration membrane. This bench scale study evaluated five different types of PAC (SA Super, G 60, KCU 6, KCU 8 and KCU 12,). The results showed that KCU 6 with larger pore size was performed better compared to other PAC when pre-coated on membrane surface. PAC pre-coating on the ceramic membrane with KCU 6 was significantly enhance NOM removal, reduced membrane fouling and improved membrane performance. Increase of total membrane resistance was suppressed to 96%. The removal of NOM components up to 92%, 58% and 56% for biopolymers, humic substances and building blocks, respectively was achieved at pre-coating dose of 30 mg/l. Adsorption was found to be the major removal mechanism of NOM. Results obtained showed that biopolymers removal are potentially correlated with enhanced membrane performance.

  7. Tailoring the heat transfer on the injection moulding cavity by plasma sprayed ceramic coatings

    Science.gov (United States)

    Bobzin, K.; Hopmann, Ch; Öte, M.; Knoch, M. A.; Alkhasli, I.; Dornebusch, H.; Schmitz, M.

    2017-03-01

    Inhomogeneous material shrinkage in injection moulding can cause warpage in thermoplastic components. To minimise the deformations of the injection moulding parts, the heat transfer during the cooling phase can be adjusted according to the local cooling demand on the surface of the mould cavity by means of plasma sprayed coatings with locally variable thermal resistance over the surface of the mould. Thermal resistance is a function of thermal conductivity and thickness of the coatings, where thermal conductivity of thermal barrier coatings can be adjusted by altering the chemical composition and the microstructure, which is depending on the thickness. This work evaluates the application of plasma sprayed coatings with variable thickness as thermal barrier coatings in the mould cavity. The thermal resistance of the coating and thereby the heat transfer from the melt into the mould will be influenced locally by varying the coating thickness over the cavity area according to the local cooling demand. Using the laser flash method, the thermal conduction of coatings with different thicknesses will be determined. On the basis of the experimentally determined thermal conduction, the effect of the coatings on the temperature field of the mould cavity will be numerically calculated and the required thickness distribution of the coating for an optimal temperature gradient will be determined.

  8. Investigation of wetting characteristics of liquid iron on dense MgAION-based ceramics by X-ray sessile drop technique

    Science.gov (United States)

    Zhang, Z. T.; Matsushita, T.; Seetharaman, S.; Li, W. C.

    2006-06-01

    The wetting characteristics of liquid iron on dense MgAION-based composite ceramics were investigated using X-ray sessile drop technique. The contact angles were measured on substrates of different composites as functions of temperature and varying partial pressures of oxygen. The results with pure argon gas showed that contact angles kept almost constant in the temperature range 1823 to 1873 K. The contact angle was found to show a slight increase with increasing boron nitride (BN) content in MgAION-BN composites. These are attributed to the higher contact angle between BN substrate and liquid iron drop compared with that obtained for MgAION substrate. When the CO-CO2-Ar gas mixtures were introduced into the system, the contact angle showed an initial quick decrease followed by a slow decrease and then a period of nearly constant contact angle at a given temperature corresponding to the steady-state condition. Even in this case, BN seemed to cause an increase in the equilibrium contact angle. The equilibrium contact angle was found to decrease with increasing temperature. XRD results indicated that the substrate was oxidized and the oxidation products combined with FeO formed by the oxidation of the iron drop to from FeAl2O4 and Mg1-xFex) These were likely to form a ternary FeO-Al2O3-MgO slag or a quaternary slag by combining with B2O3. An interesting observation is that the iron drop moved away from the original site, probably due to the Marangoni effect.

  9. Suppression of Aluminum Current Collector Dissolution by Protective Ceramic Coatings for Better High-Voltage Battery Performance.

    Science.gov (United States)

    Heckmann, Andreas; Krott, Manuel; Streipert, Benjamin; Uhlenbruck, Sven; Winter, Martin; Placke, Tobias

    2017-01-04

    Batteries based on cathode materials that operate at high cathode potentials, such as LiNi0.5 Mn1.5 O4 (LNMO), in lithium-ion batteries or graphitic carbons in dual-ion batteries suffer from anodic dissolution of the aluminum (Al) current collector in organic solvent-based electrolytes based on imide salts, such as lithium bis(trifluoromethanesulfonyl) imide (LiTFSI). In this work, we developed a protective surface modification for the Al current collector by applying ceramic coatings of chromium nitride (Crx N) and studied the anodic Al dissolution behavior. By magnetron sputter deposition, two different coating types, which differ in their composition according to the CrN and Cr2 N phases, were prepared and characterized by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and their electronic conductivity. Furthermore, the anodic dissolution behavior was studied by cyclic voltammetry and chronocoulometry measurements in two different electrolyte mixtures, that is, LiTFSI in ethyl methyl sulfone and LiTFSI in ethylene carbonate/dimethyl carbonate 1:1 (by weight). These measurements showed a remarkably reduced current density or cumulative charge during the charge process, indicating an improved anodic stability of the protected Al current collector. The coating surfaces after electrochemical treatment were characterized by means of SEM and XPS, and the presence or lack of pit formation, as well as electrolyte degradation products could be well correlated to the electrochemical results.

  10. Evaluation and Description of Friction between an Electro-Deposited Coating and a Ceramic Ball under Fretting Condition

    Directory of Open Access Journals (Sweden)

    Kyungmok Kim

    2015-07-01

    Full Text Available This article describes fretting behavior of zirconia and silicon nitride balls on an electro-deposited coating. Fretting tests are performed using a ball-on-flat configuration. The evolution of the kinetic friction coefficient is determined, along with slip ratio. Experimental results show that the steady-state friction coefficient between ceramic balls (Si3N4 and ZrO2 and an electro-deposited coating is about 0.06, lower than the value between AISI 52100 ball and the coating. After a steady-state sliding, the transition of the friction coefficient is varied with a ball. The friction coefficient for ZrO2 balls became a critical value after higher fretting cycles than those for Si3N4 and AISI 52100 balls. In addition, it is identified that two parameters can describe the transition of the friction coefficient. Finally, the evolution of the friction coefficient is expressed as an exponential or a power-law form.

  11. Characterization of Environmental Stability of Pulsed Laser Deposited Oxide Ceramic Coatings

    Energy Technology Data Exchange (ETDEWEB)

    ADAMS, THADM

    2004-03-02

    A systematic investigation of candidate hydrogen permeation materials applied to a substrate using Pulsed Laser Deposition has been performed. The investigation focused on application of leading permeation-resistant materials types (oxide, carbides, and metals) on a stainless steel substrate. and evaluation of the stability of the applied coatings. Type 304L stainless steel substrates were coated with aluminum oxide, chromium oxide, and aluminum. Characterization of the coating-substrate system adhesion was performed using scratch adhesion testing and microindentation. Coating stability and environmental susceptibility were evaluated for two conditions-air at 350 degrees Celsius and Ar-H2 at 350 degrees Celsius for up to 100 hours. Results from this study have shown the pulsed laser deposition process to be an extremely versatile technology that is capable of producing a sound coating/substrate system for a wide variety of coating materials.

  12. FORMATION MECHANISM OF TITANIUM CARBIDE CRYSTAL IN LASER SYNTHESIZED METAL-CERAMIC COMPOSITE COATING

    OpenAIRE

    BAOSHUAI DU; ZHONGWEN. ZHANG; XINHONG WANG; ZENGDA ZOU

    2011-01-01

    In situ titanium carbide reinforced iron-based composite coating was deposited on mild carbon steel using laser surface engineering (LSE) with ferrotitanium and graphite as precursor. The microstructure and phase constituents of the deposited coating were characterized. Formation mechanism of titanium carbide crystal in the composite coating was elucidated by correlating the morphology of titanium carbide and the thermal cycle experienced by the precursor during the laser treatment. It was de...

  13. Chemical vapor deposited fiber coatings and chemical vapor infiltrated ceramic matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Kmetz, M.A.

    1992-01-01

    Conventional Chemical Vapor Deposition (CVD) and Organometallic Chemical Vapor Deposition (MOCVD) were employed to deposit a series of interfacial coatings on SiC and carbon yarn. Molybdenum, tungsten and chromium hexacarbonyls were utilized as precursors in a low temperature (350[degrees]C) MOCVD process to coat SiC yarn with Mo, W and Cr oxycarbides. Annealing studies performed on the MoOC and WOC coated SiC yarns in N[sub 2] to 1,000[degrees]C establish that further decomposition of the oxycarbides occurred, culminating in the formation of the metals. These metals were then found to react with Si to form Mo and W disilicide coatings. In the Cr system, heating in N[sub 2] above 800[degrees]C resulted in the formation of a mixture of carbides and oxides. Convention CVD was also employed to coat SiC and carbon yarn with C, Bn and a new interface designated BC (a carbon-boron alloy). The coated tows were then infiltrated with SiC, TiO[sub 2], SiO[sub 2] and B[sub 4]C by a chemical vapor infiltration process. The B-C coatings were found to provide advantageous interfacial properties over carbon and BN coatings in several different composite systems. The effectiveness of these different coatings to act as a chemically inert barrier layer and their relationship to the degree of interfacial debonding on the mechanical properties of the composites were examined. The effects of thermal stability and strength of the coated fibers and composites were also determined for several difference atmospheres. In addition, a new method for determining the tensile strength of the as-received and coated yarns was also developed. The coated fibers and composites were further characterized by AES, SEM, XPS, IR and X-ray diffraction analysis.

  14. Tensile Strength and Microstructural Characterization of Uncoated and Coated HPZ Ceramic Fibers

    Science.gov (United States)

    Bansal, Narottam P.; Wheeler, Donald R.; Dickerson, Robert M.

    1996-01-01

    Tensile strengths of as-received HPZ fiber and those surface coated with BN, BN/SiC, and BN/Si3N4 have been determined at room temperature using a two-parameter Weibull distribution. Nominally approx. 0.4 micron BN and 0.2 micron SiC or Si3N4 coatings were deposited on the fibers by chemical vapor deposition using a continuous reactor. The average tensile strength of uncoated HPZ fiber was 2.0 +/- 0.56 GPa (290 +/- 81 ksi) with a Weibull modulus of 4.1. For the BN coated fibers, the average strength and the Weibull modulus increased to 2.39 +/- 0.44 GPa (346 +/- 64 ksi) and 6.5, respectively. The HPZ/BN/SiC fibers showed an average strength of 2.0 +/- 0.32 GPa (290 +/- 47 ksi) and Weibull modulus of 7.3. Average strength of the fibers having a dual BN/Si3N4 surface coating degraded to 1.15 +/- 0.26 GPa (166 +/- 38 ksi) with a Weibull modulus of 5.3. The chemical composition and thickness of the fiber coatings were determined using scanning Auger analysis. Microstructural analysis of the fibers and the coatings was carried out by scanning electron microscopy and transmission electron microscopy. A microporous silica-rich layer approx. 200 nm thick is present on the as-received HPZ fiber surface. The BN coatings on the fibers are amorphous to partly turbostratic and contaminated with carbon and oxygen. Silicon carbide coating was crystalline whereas the silicon nitride coating was amorphous. The silicon carbide and silicon nitride coatings are non-stoichiometric, non-uniform, and granular. Within a fiber tow, the fibers on the outside had thicker and more granular coatings than those on the inside.

  15. Effects of B{sub 2}O{sub 3} content and sintering temperature on crystallization and microstructure of CBS glass–ceramic coatings

    Energy Technology Data Exchange (ETDEWEB)

    Li, Pengyang [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Wang, Shubin, E-mail: shubinwang@buaa.edu.cn [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials and Engneering, Beihang University, Beijing 100191 (China); Liu, Jianggao; Feng, Mengjie; Yang, Xinwang [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China)

    2015-11-30

    Graphical abstract: (a) TEM photogram of CG3 sintered at 800 °C, crystals are obvious; (b) the XRD patterns of CG3 glass samples sintered at various temperatures; (c) SEM photogram of CG3 sintered at 800 °C; (d) Kissinger, Augis–Bennett and Ozawa kinetics plots of CG3 glass samples. - Highlights: • Combining sol–gel method with direct sintering method to reduce the temperature of coatings formation. • Characterizing CaO–SiO{sub 2}–B{sub 2}O{sub 3} glass–ceramic coatings on porous substrates. • Surface crystallization of CBS glass–ceramic coatings: nucleation and kinetics. • Activation energies for crystal growth in CBS glass–ceramics with different contents of B{sub 2}O{sub 3}. - Abstract: Borosilicate glass–ceramics precursors with varying compositional ratios in the CaO–SiO{sub 2}–B{sub 2}O{sub 3} (CBS) system were synthesized by sol–gel method. The precursors were calcined at 1200 °C for 2 h to form glass powders. The glass–ceramics were prepared by overlaying glass slurries on the substrates before sintering at different temperatures. The as-prepared glasses and glass–ceramics were characterized by differential scanning calorimetry and X-ray diffraction. The crystallization activation energies (E{sub c}) were calculated using the Kissinger method from DSC results. The morphology and crystallization behavior of the glass–ceramics were monitored by scanning electron microscopy. Both glass transition and crystallization temperatures decreased, however, the metastable zone increased. The E{sub c} values of CBS glasses and glass–ceramics were 254.1, 173.2 and 164.4 kJ/mol with increasing B{sub 2}O{sub 3} content, whereas that of the calcined G3 glass was 104.9 kJ/mol. Finally, the coatings were prepared at a low temperature (700 °C). The crystals that grew on the surface of multilayer coatings demonstrated heterogeneous surface nucleation and crystallization after heat-treatment from 700 °C to 850 °C for 4 h.

  16. Removal of coatings and surfaces on metallic, mineral and ceramic materials

    Energy Technology Data Exchange (ETDEWEB)

    Bach, F.W.; Redeker, C. [Dortmund Univ. (Germany). Inst. for Materials Engineering

    2001-07-01

    Various techniques for use in decontamination in decommissioning of nuclear facilities are presented. The methods may be classified by their physical effects, namely chemical electrochemical, mechanical and thermal. A main issue is the dryice-laserbeam-blasting process. By dryice-laserbeam-blasting surfaces of concrete and ceramic materials can be removed. (orig.)

  17. Effect of Fe{sup 3+} ions on the thermal and optical properties of the ceramic coating grown in-situ on AZ31 Mg Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Lu Songtao [Department of Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Qin Wei [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wu Xiaohong, E-mail: wuxiaohong@hit.edu.cn [Department of Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Wang Xiaodong [Department of Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Zhao Guimei [China Academy of Space Technology, Beijing 100094 (China)

    2012-07-16

    This research investigates the effect of Fe{sub 2}(SO{sub 4}){sub 3} on the thermal and optical properties of the ceramic coatings formed on AZ31 Mg alloy. The different ceramic coatings were obtained by plasma electrolytic oxidation (PEO) in electrolytes that contain varied concentrations of Fe{sub 2}(SO{sub 4}){sub 3}. The microstructure, element distribution, composition as well as the thermal and optical properties of the coatings were studied with scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray Diffraction (XRD), UV-VIS-NIR spectrophotometer and infrared reflectometer. The results show that all of the coatings prepared were mainly composed with MgO, with trace-amount of Fe{sub 3}O{sub 4} presents and Fe seems entered into the MgO crystal structure. With the increasing of the concentration of Fe{sub 2}(SO{sub 4}){sub 3}, the solar absorptance and infrared emittance increased initially but then remain stable. We found that at the concentrations 8 g L{sup -1}, the coating has the highest solar absorptance (0.94) and infrared emittance (0.83). Our results show that coatings formed with this method could be useful as a thermal control coating in a variety of applications, such as in the spacecraft. - Highlights: Black-Right-Pointing-Pointer Thermal control coatings on AZ31 Mg alloy were prepared by the plasma electrolytic oxidation (PEO) method. Black-Right-Pointing-Pointer The coatings were mainly composed with MgO, with trace-amount of Fe{sub 3}O{sub 4} presents. Black-Right-Pointing-Pointer The using of Fe{sup 3+} in the electrolyte improves the thermal and optical properties of the obtained MgO coating. Black-Right-Pointing-Pointer The thermal control coating obtained by PEO has high solar absorptance (0.94) and infrared emittance (0.83).

  18. State of residual stress in laser-deposited ceramic composite coatings on aluminum alloys

    NARCIS (Netherlands)

    Kadolkar, P. B.; Watkins, T. R.; De Hosson, J. Th. M.; Kooi, B. J.; Dahotre, N. B.

    2007-01-01

    The nature and magnitude of the residual stresses within laser-deposited titanium carbide (TiC) coatings on 2024 and 6061 aluminum (Al) alloys were investigated. Macro- and micro-stresses within the coatings were determined using an X-ray diffraction method. Owing to increased debonding between the

  19. In vivo evaluation of CaO-SiO2-P2O5-B2O3 glass-ceramics coating on Steinman pins.

    Science.gov (United States)

    Lee, Jae Hyup; Hong, Kug Sun; Baek, Hae-Ri; Seo, Jun-Hyuk; Lee, Kyung Mee; Ryu, Hyun-Seung; Lee, Hyun-Kyung

    2013-07-01

    Surface coating using ceramics improves the bone bonding strength of an implant. We questioned whether a new type of glass-ceramics (BGS-7) coating (CaO-SiO2 -P2 O5 -B2 O3 ) would improve the osseointegration of Steinman pins (S-pins) both biomechanically and histomorphometrically. An in vivo study was performed using rabbits by inserting three S-pins into each iliac bone. The pins were 2.2-mm S-pins with a coating of 30-μm-thick BGS-7 and 550-nm-thick hydroxyapatite (HA), as opposed to an S-pin without coating. A tensile strength test and histomorphometrical evaluation was performed. In the 2-week group, the BGS-7 implant showed a significantly higher tensile strength than the S-pin. In the 4- and 8-week groups, the BGS-7 implants had significantly higher tensile strengths than the S-pins and HA implants. The histomorphometrical study revealed that the BGS-7 implant had a significantly higher contact ratio than the S-pin and HA implants in the 4-week group. The biomechanical and histomorphometrical tests showed that the BGS-7 coating had superior bone bonding properties than the groups without the coating from the initial stage of insertion. The BGS-7 coating of an S-pin will enhance the bone bonding strength, and there might also be an advantage in human bone bonding.

  20. The effect of colouring agent on the physical properties of glass ceramic produced from waste glass for antimicrobial coating deposition

    Science.gov (United States)

    Juoi, J. M.; Ayoob, N. F.; Rosli, Z. M.; Rosli, N. R.; Husain, K.

    2016-07-01

    Domestic waste glass is utilized as raw material for the production of glass ceramic material (GCM) via sinter crystallisation route. The glass ceramic material in a form of tiles is to be utilized for the deposition of Ag-TiO2 antimicrobial coating. Two types of soda lime glass (SLG) that are non-coloured and green SLG are utilised as main raw materials during the batch formulation in order to study the effect of colouring agent (Fe2O3) on the physical and mechanical properties of glass ceramic produced. Glass powder were prepared by crushing bottles using hammer milled with milling machine and sieved until they passed through 75 µm sieve. The process continues by mixing glass powder with ball clay with ratio of 95:5 wt. %, 90:10 wt. % and 85:15 wt. %. Each batch mixture was then uniaxial pressed and sintered at 800°C, 825 °C and 850 °C. The physical and mechanical properties were then determined and compared between those produced from non-coloured and green coloured SLG in order to evaluate the effect of colouring agent (Fe2O3) on the GCM produced. The optimum properties of non-coloured SLG is produced with smaller ball clay content (10 wt. %) compared to green SLG (15 wt. %). The physical properties (determined thru ASTM C373) of the optimized GCM produced from non-coloured SLG and green SLG are 0.69 % of porosity, 1.92 g/cm3 of bulk density, 0.36 % of water absorption; and 1.96 % of porosity, 2.69 g/cm3 of bulk density, 0.73 % of water absorption; respectively. Results also indicate that the most suitable temperature in producing GCM from both glasses with optimized physical and mechanical properties is at 850 °C.

  1. Effect of silicon carbide ceramic coating process on the mirror surface quality

    Science.gov (United States)

    Wang, Peipei; Wang, Li; Wang, Gang; Bai, Yunli; Wang, Peng; Xiao, Zhenghang

    2016-10-01

    Silicon carbide, as a new reflector material, its excellent physical and chemical properties has been widely recognized by the industry. In order to make SiC mirror better used in space optical system, we used digital coating equipment during its coating process. By using ion-assisted electron evaporation method, we got a complete metal reflective film system on the surface of finely polished silicon carbide mirror. After automated coating process, by adjusting the coating parameters during the process, the surface roughness of silicon carbide improved from 7.8 nm to 5.1 nm, and the average optical reflectance of the surface reached 95% from visible to near-infrared. The metal reflective film system kept well after annealing and firmness test. As a result, the work of this paper will provide an important reference for high-precision coating process on large diameter SiC mirror.

  2. Solar Photocatalytic Removal of Chemical and Bacterial Pollutants from Water Using Pt/TiO2-Coated Ceramic Tiles

    Directory of Open Access Journals (Sweden)

    S. P. Devipriya

    2012-01-01

    Full Text Available Semiconductor photocatalysis has become an increasingly promising technology in environmental wastewater treatment. The present work reports a simple technique for the preparation of platinum-deposited TiO2 catalysts and its immobilization on ordinary ceramic tiles. The Pt/TiO2 is characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, energy dispersive X-ray spectroscopy (EDAX, and diffuse reflectance spectroscopy (DRS. Deposition of Pt on TiO2 extends the optical absorption of the latter to the visible region which makes it attractive for solar energy application. Optimum loading of Pt on TiO2 was found to be 0.5%. The Pt/TiO2 is coated on ceramic tiles and immobilized. This catalyst was found effective for the solar photocatalytic removal of chemical and bacterial pollutants from water. Once the parameters are optimized, the Pt/TiO2/tile can find application in swimming pools, hospitals, water theme parks, and even industries for the decontamination of water.

  3. Preparation and photo-catalytic activity of TiO2-coated medical stone-based porous ceramics

    Science.gov (United States)

    Gao, Ru-qin; Hou, Xin-mei

    2013-06-01

    Medical stone-based porous ceramics as a carrier were prepared by ultra-fine grinding and low-temperature sintering method. Nano-TiO2 thin films were loaded on the carrier by chemical liquid deposition method using titanium tetrachloride as a precursor. The micro-morphology and microstructure of the synthesized samples were characterized using X-ray diffraction, scanning electron microscopy with energy dispersive spectrometry, and mercury injection method. The photo-catalytic activity of the TiO2 thin films was investigated by degrading formaldehyde. The main crystalline phase in the TiO2 thin films calcined at 550°C is anatase with the average particle size about 10 nm. The specific surface area of the carrier-coated nano-TiO2 increases from 3.68 to 5.32 m2/g. The formaldehyde removal rate of the TiO2/medical stone-based porous ceramics irradiated under an ultraviolet lamp for 120 min reaches 85.6%.

  4. Synthesis mechanism of low-voltage praseodymium oxide doped zinc oxide varistor ceramics prepared through modified citrate gel coating.

    Science.gov (United States)

    Abdullah, Wan Rafizah Wan; Zakaria, Azmi; Ghazali, Mohd Sabri Mohd

    2012-01-01

    High demands on low-voltage electronics have increased the need for zinc oxide (ZnO) varistors with fast response, highly non-linear current-voltage characteristics and energy absorption capabilities at low breakdown voltage. However, trade-off between breakdown voltage and grain size poses a critical bottle-neck in the production of low-voltage varistors. The present study highlights the synthesis mechanism for obtaining praseodymium oxide (Pr(6)O(11)) based ZnO varistor ceramics having breakdown voltages of 2.8 to 13.3 V/mm through employment of direct modified citrate gel coating technique. Precursor powder and its ceramics were examined by means of TG/DTG, FTIR, XRD and FESEM analyses. The electrical properties as a function of Pr(6)O(11) addition were analyzed on the basis of I-V characteristic measurement. The breakdown voltage could be adjusted from 0.01 to 0.06 V per grain boundary by controlling the amount of Pr(6)O(11) from 0.2 to 0.8 mol%, without alteration of the grain size. The non-linearity coefficient, α, varied from 3.0 to 3.5 and the barrier height ranged from 0.56 to 0.64 eV. Breakdown voltage and α lowering with increasing Pr(6)O(11) content were associated to reduction in the barrier height caused by variation in O vacancies at grain boundary.

  5. Load-deflection and surface properties of coated and conventional superelastic orthodontic archwires in conventional and metal-insert ceramic brackets

    Directory of Open Access Journals (Sweden)

    Shiva Alavi

    2012-01-01

    Full Text Available Background: Properties of coated archwires, which have been introduced for esthetic demands during orthodontic treatments, along with the use of tooth-colored brackets, are not clear. The aim of this study is to compare the load-deflection and surface properties of coated superelastic archwires with conventional superelastic archwires in conventional and metal-insert ceramic brackets. Materials and Methods: In this experimental study, 3 types of archwires including ultraesthetic polycoated, ultraesthetic epoxyresin coated and conventional (uncoated superelastic nickel-titanium (NiTi archwires were used in each of 2 types of brackets including conventional and metal-insert ceramic. To simulate oral environment, all specimens were incubated in artificial saliva using thermocycling model and then were tested in three-bracket bending test machine. Loading and unloading forces, plateau gap and end load deflection point (ELDP were recorded. Archwires were investigated with a stereomicroscope before and after the experiment. Two-way ANOVA and Tukey tests were used at P<0.05. Results: Epoxyresin archwires produced lower forces (19 to 310 gr compared to polycoated (61 to 359 gr and NiTi (61 to 415 gr (P<0.0001. The maximum ELDP (0.43 mm was observed in epoxyresin archwires (P<0.001. Coatings of some epoxyresin wires were torn and of polycoated wires peeled off. Conventional ceramic bracket produced higher loading forces with polycoated and NiTi archwires and lower unloading forces with all 3 types of archwires compared to metal-insert type (P<0.05. Conclusion: Epoxyresin-coated archwire had the lowest force and highest ELDP. Coatings were not durable in these experimental conditions. Conventional ceramic bracket produced higher frictional force compared to metal-insert type.

  6. Microstructure Analysis of Laser Remelting for Thermal Barrier Coatings on the Surface of Titanium Alloy

    Directory of Open Access Journals (Sweden)

    Lu Bin

    2016-01-01

    Full Text Available In this paper, the preparation and organization performance of thermal barrier coatings (TCBs on the surface of titanium were studied experimentally. Nanostructured 8 wt% yttria partially stabilized zirconia coatings were deposited by air plasma spraying. The microstructure of nanostructured and the conventional coating was studied after laser remelting. It has shown that formed a network of micro-cracks and pits after laser remelting on nanostructured coatings. With the decrease of the laser scanning speed, mesh distribution of micro cracks was gradually thinning on nanostructured coatings. Compared with conventional ceramic layers, the mesh cracks of nanostructured coating is dense and the crack width is small.

  7. Effect of Simulated High Hydrogen Content Combustion Environments on Abradable Properties of Ceramic Turbine Coatings

    Science.gov (United States)

    Basu Majumder, Madhura

    Air plasma sprayed (APS) abradable coatings are used in the turbine hot section to reduce the stator-rotor gap, minimizing gas leakage. These coatings are designed to exhibit controlled removal of material in thin layers when the turbine blades sweep through the coating, which protects the mechanical integrity of the turbine blade. In an effort to lower CO2 emissions, high H2 content fuel is being explored. This change in chemical composition of the fuel may affect the microstructure, abradability and durability of the coatings at turbine operational temperatures. The presence of high water vapor in the combustion chamber leads to accelerated degradation of the sacrificial coating materials. In this work, zirconia based composite materials with a machinable phase and varied porosity have been used to study microstructural evolution, thermal and chemical stability of the phases and abradable characteristics of baseline coating systems in both humid and dry environments. Investigation of the mechanisms that control the removal of materials and performance of abradable coatings through thermo-mechanical tests will be discussed.

  8. Sliding Wear Behavior of Plasma Sprayed Zirconia Coating on Cast Aluminum against Silicon Carbide Ceramic

    Institute of Scientific and Technical Information of China (English)

    Thuong-Hien LE; Young-Hun CHAE; Seock-Sam KIM

    2005-01-01

    The sliding wear behaviors of ZrO2-22 wt pct MgO (MZ) and ZrO2-8 wt pct Y2O3 (YZ) coatings deposited on a cast aluminum alloy with bond layer (NiCrCoAlY) by plasma spray were investigated under dry test conditions at room temperature. Under all load conditions, the wear mechanisms of the MZ and YZ coatings were almost the same.The material transfer and pullout were involved in the wear process of the studied coatings under the test conditions.The wear rate of the MZ coating was less than that of the YZ coating. While increasing the normal load, the wear rates of the MZ and YZ coatings increased. SEM was used to examine the worn surfaces and to elucidate likely wear mechanisms. Energy dispersive X-ray spectroscopy (EDX) analysis of the worn surfaces indicated that material transfer occurred in the direction from the SiC ball to the disk. Fracture toughness had a significant influence on the wear performance of the coatings. It was suggested that the material transfer played an important role in the wear behavior.

  9. Plasma Spray-Physical Vapor Deposition (PS-PVD) of Ceramics for Protective Coatings

    Science.gov (United States)

    Harder, Bryan J.; Zhu, Dongming

    2011-01-01

    In order to generate advanced multilayer thermal and environmental protection systems, a new deposition process is needed to bridge the gap between conventional plasma spray, which produces relatively thick coatings on the order of 125-250 microns, and conventional vapor phase processes such as electron beam physical vapor deposition (EB-PVD) which are limited by relatively slow deposition rates, high investment costs, and coating material vapor pressure requirements. The use of Plasma Spray - Physical Vapor Deposition (PS-PVD) processing fills this gap and allows thin (coatings of less than 100 microns to be generated with the flexibility to tailor microstructures by changing processing conditions. Coatings of yttria-stabilized zirconia (YSZ) were applied to NiCrAlY bond coated superalloy substrates using the PS-PVD coater at NASA Glenn Research Center. A design-of-experiments was used to examine the effects of process variables (Ar/He plasma gas ratio, the total plasma gas flow, and the torch current) on chamber pressure and torch power. Coating thickness, phase and microstructure were evaluated for each set of deposition conditions. Low chamber pressures and high power were shown to increase coating thickness and create columnar-like structures. Likewise, high chamber pressures and low power had lower growth rates, but resulted in flatter, more homogeneous layers

  10. Potential benefits of a ceramic thermal barrier coating on large power generation gas turbine

    Science.gov (United States)

    Clark, J. S.; Nainiger, J. J.

    1977-01-01

    Thermal barrier coating design option offers benefit in terms of reduced electricity costs when used in utility gas turbines. Options considered include: increased firing temperature, increased component life, reduced cooling air requirements, and increased corrosion resistance (resulting in increased tolerance for dirty fuels). Performance and cost data were obtained. Simple, recuperated and combined cycle applications were considered, and distillate and residual fuels were assumed. The results indicate that thermal barrier coatings could produce large electricity cost savings if these coatings permit turbine operation with residual fuels at distillate-rated firing temperatures. The results also show that increased turbine inlet temperature can result in substantial savings in fuel and capital costs.

  11. Optimization of usage parameters of ceramic coatings in high temperature applications using Taguchi design

    Directory of Open Access Journals (Sweden)

    Mohammed Yunus

    2011-08-01

    Full Text Available The durability and efficiency of high temperature components used in aerospace industry are improved by the usage of thermal barrier coatings (TBC.The characterization of TBC requires a better understanding of mechanical and tribological properties along with their failure mechanisms which are to be thoroughly investigatedto estimate their performance. Thermal barrier (TB and thermal cycling resistance (TCR parameters are considered to be very important at high temperature applications. Thermal tests were carried out on three different types of coatings namely, Alumina (A, Alumina-Titania (AT and partially stabilized zirconia (PSZ, in the present study. Using Taguchi approach, optimization of various TBC parameters like temperature on heated surface of coating,thicknesses and types of coatings was done and the significance of TB and TCR were also investigated using S/N ratio and ANOVA. The experimental results were found to be in good agreement with statistical results obtained by Taguchi technology.

  12. X-ray residual stress analysis of a ceramic thermal barrier coating undergoing thermal cycling

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, D.W. (Dept. of Materials Science and Engineering, Northwestern Univ., Evanston, IL (United States)); Faber, K.T. (Dept. of Materials Science and Engineering, Northwestern Univ., Evanston, IL (United States))

    1993-11-25

    The residual stress of a ZrO[sub 2]-8%Y[sub 2]O[sub 3] thermal barrier coating was determined as a function of thermal cycling. Samples were thermally cycled from 400 C to 1000 C in air. After a few cycles the samples exhibited a value of compressive residual stress consistent with that determined by considering the thermal expansion coefficients of the coating and substrate. Stress relief occurs in the ZrO[sub 2]-Y[sub 2]O[sub 3] coating, increasing in both frequency and magnitude with increasing number of thermal cycles. This behavior is explained in terms of a model of failure of coatings in compression. (orig.)

  13. Catalytic surface effect on ceramic coatings for an aeroassisted orbital transfer vehicle

    Science.gov (United States)

    Steward, D. A.; Leiser, D. B.

    1984-01-01

    Surface catalytic efficiencies of glassy coatings were determined from a reaction boundary layer computation and arc-jet data. The catalytic efficiencies of the various coatings examined are discussed in terms of their reaction-rate constants. These constants are a function of the wall temperature (1290 K to 2000 K). In addition, the advantage of a thermal protection system for a bent biconic, aeroassisted orbital transfer vehicle with a low surface catalytic efficiency is discussed.

  14. Diamond-like carbon and ceramic materials as protective coatings grown by pulsed laser deposition

    OpenAIRE

    Perera Mercado, Yibran Argenis

    2004-01-01

    A rather large number of nitride, carbide, and oxide thin films are used as hard and wear-resistant coatings, for optical, corrosive, and refractory applications that are of crucial importance. Additional requirements place even more stringent conditions on the deposition processes. The properties of coatings deposited by pulsed laser deposition are determined by the deposition parameters, the composition of the PLD plasma and its ionization states, the substrate conditions, etc.. In this way...

  15. Durability of ceramic coatings in 14,000 hours service in a marine diesel engine

    Energy Technology Data Exchange (ETDEWEB)

    Levy, A.V.; Macadam, S.

    1988-01-01

    A representative selection of diesel engine combustion zone components coated with plasma sprayed zirconia thermal barrier systems was analyzed after 14,000 hours of practical engine service. The analysis consisted of determining the degree of success of the different coating systems and suggesting probable mechanisms of failure. The coating systems under investigation include a flame stabilized and a pre-alloyed 8% Y/sub 2/O/sub 3/-ZrO/sub 2/, and a flame stabilized 22% MgO-ZrO/sub 2/. All three of these systems applied to piston crowns survived engine service with no noticeable deterioration of any kind. Coating performance on valve faces was mixed. The 22% MgO-ZrO/sub 2/ valve coating consistently spalled at or near the interface with the bond coat. This failure was due to the volume expansion associated with the observed phase transformation of the zirconia to the monoclinic structure. The flame stabilized 8% Y/sub 2/O/sub 3/-ZrO/sub 2/ on the valves consistently failed over large regions while the pre-alloyed coating of the same composition survived with only minimal loss. The performance pattern of all three systems after 14,000 hours closely resembled their performance determined during a similar study at the conclusion of 9000 hours engine service. This strongly suggests that the successful coating system-engine component combinations indicated have the durability to reliably serve through the overhaul lifetime in this type of service (18,000 to 22,000 hours).

  16. New nano-sized Al2O3-BN coating 3Y-TZP ceramic composites for CAD/CAM-produced all-ceramic dental restorations. Part I. Fabrication of powders.

    Science.gov (United States)

    Yang, Se Fei; Yang, Li Qiang; Jin, Zhi Hao; Guo, Tian Wen; Wang, Lei; Liu, Hong Chen

    2009-06-01

    Partially sintered 3 mol % yttria-stabilized tetragonal zirconium dioxide (ZrO(2), zirconia) polycrystal (3Y-TZP) ceramics are used in dental posterior restorations with computer-aided design-computer-aided manufacturing (CAD/CAM) techniques. High strength is acquired after sintering, but shape distortion of preshaped compacts during their sintering is inevitable. The aim of this study is to fabricate new machinable ceramic composites with strong mechanical properties that are fit for all-ceramic dental restorations. Aluminum oxide (Al(2)O(3))-coated 3Y-TZP powders were first prepared by the heterogeneous precipitation method starting with 3Y-TZP, Al(NO(3))(3) . 9H(2)O, and ammonia, then amorphous boron nitride (BN) was produced and the as-received composite powders were coated via in situ reaction with boric acid and urea. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to analyze the status of Al(2)O(3)-BN on the surface of the 3Y-TZP particles. TEM micrographs show an abundance of Al(2)O(3) particles and amorphous BN appearing uniformly on the surface of the 3Y-TZP particles after the coating process. The size of the Al(2)O(3) particles is about 20 nm. The XRD pattern shows clearly the peak of amorphous BN among the peaks of ZrO(2).

  17. The Development of 2700-3000 F Environmental Barrier Coatings for SiC/SiC Ceramic Matrix Composites: Challenges and Opportunities

    Science.gov (United States)

    Zhu, Dongming

    2015-01-01

    Environmental barrier coatings (EBCs) and SiCSiC ceramic matrix composites (CMCs) systems will play a crucial role in future turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. The development of prime-reliant environmental barrier coatings is a key to enable the applications of the envisioned 2700-3000F EBC - CMC systems to help achieve next generation engine performance and durability goals. This paper will primarily address the performance requirements and design considerations of environmental barrier coatings for turbine engine applications. The emphasis is placed on current NASA candidate environmental barrier coating systems for SiCSiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. The efforts have been also directed to developing prime-reliant, self-healing 2700F EBC bond coat; and high stability, lower thermal conductivity, and durable EBC top coats. Major technical barriers in developing environmental barrier coating systems, the coating integrations with next generation CMCs having the improved environmental stability, cyclic durability, erosion-impact resistance, and long-term system performance will be described. The research and development opportunities for turbine engine environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling will be discussed.

  18. Manufacture of dense CAU-10-H coatings for application in adsorption driven heat pumps: optimization and characterization

    NARCIS (Netherlands)

    De Lange, M.F.; Zeng, T.; Vlugt, T.J.H.; Gascon, J.; Kapteijn, F.

    2015-01-01

    CAU-10-H displays a highly suitable step-wise water adsorption behaviour for application in adsorption driven heat pumps and chillers. For actual application, manufacturing of coatings of this material on thermally conductive surfaces is highly desired. Direct, single-step, crystallization of

  19. New high-temperature resistant ceramic coating to accelerate expansion into new markets%高温耐磨的陶瓷涂料新品加速拓展新市场

    Institute of Scientific and Technical Information of China (English)

    肖艳

    2012-01-01

    Ceramic coating is a very important fine chemical products,its application has been deep into all areas of the national economy.High temperature ceramic coating is widely used in aerospace,electronics,automotive,machinery and other high-tech fields.According to a new generation ceramic coating and then a new,analyzed the main component of the ceramic coating,film theory and application;study of high temperature resistant ceramic coatings and ceramic coatings for wear-resistant waterproof structure and performance characteristics;describes new nano-ceramic coatings available introduced several kinds of typical high-temperature resistant ceramic coating waterproof new.%陶瓷涂料是一种很重要的精细化工产品,其应用已深入到国民经济的各个领域。耐高温陶瓷涂料更是广泛应用于航空航天、电子、汽车、机械制造等高技术领域。根据新型陶瓷涂料再出换代新品,分析了陶瓷涂料的主要成分、成膜原理及应用范围;研究了高温耐磨陶瓷涂料和耐磨防水陶瓷涂料的结构和性能特点;阐述了纳米陶瓷涂料新品面市,介绍了国内几种典型的高温耐磨防水陶瓷涂料新品。

  20. Multilayer (TiN, TiAlN) ceramic coatings for nuclear fuel cladding

    Science.gov (United States)

    Alat, Ece; Motta, Arthur T.; Comstock, Robert J.; Partezana, Jonna M.; Wolfe, Douglas E.

    2016-09-01

    In an attempt to develop an accident-tolerant fuel (ATF) that can delay the deleterious consequences of loss-of-coolant-accidents (LOCA), multilayer coatings were deposited onto ZIRLO® coupon substrates by cathodic arc physical vapor deposition (CA-PVD). Coatings were composed of alternating TiN (top) and Ti1-xAlxN (2-layer, 4-layer, 8-layer and 16-layer) layers. The minimum TiN top coating thickness and coating architecture were optimized for good corrosion and oxidation resistance. Corrosion tests were performed in static pure water at 360 °C and 18.7 MPa for up to 90 days. The optimized coatings showed no spallation/delamination and had a maximum of 6 mg/dm2 weight gain, which is 6 times smaller than that of a control sample of uncoated ZIRLO® which showed a weight gain of 40.2 mg/dm2. The optimized architecture features a ∼1 μm TiN top layer to prevent boehmite phase formation during corrosion and a TiN/TiAlN 8-layer architecture which provides the best corrosion performance.

  1. FUNCTIONALLY GRADED ALUMINA/MULLITE COATINGS FOR PROTECTION OF SILICON CARBIDE CERAMIC COMPONENTS FROM CORROSION

    Energy Technology Data Exchange (ETDEWEB)

    Prof. Stratis V. Sotirchos

    2001-02-01

    The main objective of this research project was the formulation of processes that can be used to prepare compositionally graded alumina/mullite coatings for protection from corrosion of silicon carbide components (monolithic or composite) used or proposed to be used in coal utilization systems (e.g., combustion chamber liners, heat exchanger tubes, particulate removal filters, and turbine components) and other energy-related applications. Since alumina has excellent resistance to corrosion but coefficient than silicon carbide, the key idea of this project has been to develop graded coatings with composition varying smoothly along their thickness between an inner (base) layer of mullite in contact with the silicon carbide component and an outer layer of pure alumina, which would function as the actual protective coating of the component. (Mullite presents very good adhesion towards silicon carbide and has thermal expansion coefficient very close to that of the latter.)

  2. J-Integral of Interfacial Crack Between Metal-Base Ceramic Coating and Steel

    Institute of Scientific and Technical Information of China (English)

    XU Lianyong; JING Hongyang; HE Ying

    2009-01-01

    The definition ofJ-integral of interfacial crack was introduced.The three.point bending tests were carried out to obtain the criticaI lOading values when the interfacial crack initiation occurred between coatings and substrates.The finite element analysis(FEA)was adopted to analyze the stress distribution in the specimens and compute the J-integral of the interfaciaI crack between LX88A coating and Chinese 0345 steel.The results showed that the average value of critical J-integral iS 0.70 N/m.which can be taken as the fracture parameter to evaluate the interfaciaI fracture behavior for the three-point bending specimens of LX88A coating/Q345 steel system.

  3. Performance properties of electro-spark deposited carbide-ceramic coatings modified by laser beam

    Science.gov (United States)

    Radek, Norbert; Bartkowiak, Konrad

    The work presented in this paper determines the influence of the laser treatment process on the properties of electrospark coatings. The properties after laser treatment were examined by microstructure analysis, microhardness, roughness and adhesion tests. The studies were conducted using WC-Co-Al2O3 electrodes produced by sintering nanostructural powders. The anti-wear coatings were first deposited by an EIL-8A apparatus on C45 carbon steel and then laser melted within various process parameters. In this case Nd:YAG laser (BLS 720 model) was applied. The electro-spark deposited coatings are very promising to improve abrasive wear resistance of tools and machine parts, which was indicated by tribological tests.

  4. Platelet-rich plasma and fibrin glue-coated bioactive ceramics enhance growth and differentiation of goat bone marrow-derived stem cells.

    Science.gov (United States)

    Nair, Manitha B; Varma, H K; John, Annie

    2009-07-01

    New biotechnologies such as tissue engineering require functionally active cells within supportive matrices where the physical and chemical stimulus provided by the matrix is indispensable to determine the cellular behavior. This study has investigated the influence of platelet-rich plasma (PRP) and fibrin glue (FG) on the functional activity of goat bone marrow-derived mesenchymal stem cells (gBMSCs) that differentiated into the osteogenic lineage. To achieve this goal, PRP and FG were separately coated on bioactive ceramics like hydroxyapatite (HA) and silica-coated HA (HASi), on which gBMSCs were seeded and induced to differentiate into the osteogenic lineage for 28 days. The cells were then analyzed for viability (lactate dehydrogenase assay: acridine orange and ethidium bromide staining), morphology (scanning electron microscopy), proliferation (picogreen assay), cell cycle assay (propidium iodide staining), and differentiation (alkaline phosphatase [ALP] activity and real-time PCR analysis of ALP, osteocalcin, and osteopontin gene). It has been observed that PRP and FG have appreciably favored the viability, spreading, and proliferation of osteogenic-induced gBMSCs. The osteopontin and osteocalcin expression was significantly enhanced on PRP- and FG-coated HA and HASi, but PRP had effect on neither ALP expression nor ALP activity. The results of this study have depicted that FG-coated ceramics were better than PRP-coated and bare matrices. Among all, the excellent performance was shown by FG coated HASi, which may be attributed to the communal action of the stimulus emanated by Si in HASi and the temporary extracellular matrix provided by FG over HASi. Thus, we can conclude that PRP or FG in combination with bioactive ceramics could possibly enhance the functional activity of cells to a greater extent, promoting the hybrid composite as a promising candidate for bone tissue engineering applications.

  5. Assessment of ceramic membrane filters

    Energy Technology Data Exchange (ETDEWEB)

    Ahluwalia, R.K.; Geyer, H.K.; Im, K.H. [and others

    1995-08-01

    The objectives of this project include the development of analytical models for evaluating the fluid mechanics of membrane coated, dead-end ceramic filters, and to determine the effects of thermal and thermo-chemical aging on the material properties of emerging ceramic hot gas filters. A honeycomb cordierite monolith with a thin ceramic coating and a rigid candle filter were evaluated.

  6. Synthesis Mechanism of Low-Voltage Praseodymium Oxide Doped Zinc Oxide Varistor Ceramics Prepared Through Modified Citrate Gel Coating

    Directory of Open Access Journals (Sweden)

    Wan Rafizah Wan Abdullah

    2012-04-01

    Full Text Available High demands on low-voltage electronics have increased the need for zinc oxide (ZnO varistors with fast response, highly non-linear current-voltage characteristics and energy absorption capabilities at low breakdown voltage. However, trade-off between breakdown voltage and grain size poses a critical bottle-neck in the production of low-voltage varistors. The present study highlights the synthesis mechanism for obtaining praseodymium oxide (Pr6O11 based ZnO varistor ceramics having breakdown voltages of 2.8 to 13.3 V/mm through employment of direct modified citrate gel coating technique. Precursor powder and its ceramics were examined by means of TG/DTG, FTIR, XRD and FESEM analyses. The electrical properties as a function of Pr6O11 addition were analyzed on the basis of I-V characteristic measurement. The breakdown voltage could be adjusted from 0.01 to 0.06 V per grain boundary by controlling the amount of Pr6O11 from 0.2 to 0.8 mol%, without alteration of the grain size. The non-linearity coefficient, α, varied from 3.0 to 3.5 and the barrier height ranged from 0.56 to 0.64 eV. Breakdown voltage and α lowering with increasing Pr6O11 content were associated to reduction in the barrier height caused by variation in O vacancies at grain boundary.

  7. Tissue-engineered triphasic ceramic coated hydroxyapatite induced bone formation and vascularization at an extraskeletal site in a rat model

    Indian Academy of Sciences (India)

    Manitha B Nair; H K Varma; P V Mohanan; Annie John

    2011-12-01

    Tissue-engineered bone regeneration has attracted much attention because of its high clinical demand for restoration of injured tissues. In the present study, we have evaluated the capability of bare (without cells) and tissue-engineered (with osteogenic-induced rat Mesenchymal Stem Cells (MSCs)) bioactive ceramics such as hydroxyapatite (HA) and triphasic ceramic-coated hydroxyapatite (HASi) to mediate vascularisation and osteoinduction at an extraskeletal site of rat model. The viability, proliferation and osteogenic differentiation of MSCs on the scaffolds were assessed in vitro and thereby established the capability of HASi in providing a better structural habitat than HA. The vascular invasion was relatively low in bare and tissueengineered HA at 2 and 4 weeks. Interestingly, the implantation site was well vascularised with profuse ingrowth of blood capillaries in HASi groups, with preference for tissue-engineered HASi groups. Similarly, neo-osteogenesis studies were shown only by tissue-engineered HASi groups. The ingrowth of numerous osteoblast-like cells was seen around and within the pores of the material in bare HASi and tissue-engineered HASi groups (very low cellular infiltration in bare HA groups), but there was no osteoid deposition. The positive impact in forming bone in tissue-engineered HASi groups is attributable to the scaffold and to the cells, with the first choice for scaffold because both HA and HASi were engineered simultaneously with the cells from same source and same passage. Thus, highly porous interconnected porous structure and appropriate chemistry provided by HASi in combination with osteogenic-induced MSCs facilitated better vascularisation that lead to neo-osteogenesis.

  8. Photocatalytic and biocidal activities of novel coating systems of mesoporous and dense TiO{sub 2}-anatase containing silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Roldán, María V. [Laboratorio de Materiales Cerámicos, FCEIA-UNR, IFIR-CONICET, Pellegrini 250, Rosario S2000BTP (Argentina); Oña, Paula de [Laboratorio de Microbiología Molecular, FCByF-UNR-CONICET, Suipacha 531, Rosario S2002LRK (Argentina); Castro, Yolanda; Durán, Alicia [Instituto de Cerámica y Vidrio (CSIC), Campus de Cantoblanco, 28049, Madrid (Spain); Faccendini, Pablo; Lagier, Claudia [IQUIR-UNR-CONICET, Suipacha 531, Rosario S2002LRK (Argentina); Grau, Roberto, E-mail: robertograu@fulbrightmail.org [Laboratorio de Microbiología Molecular, FCByF-UNR-CONICET, Suipacha 531, Rosario S2002LRK (Argentina); Pellegri, Nora S., E-mail: pellegri@fceia.unr.edu.ar [Laboratorio de Materiales Cerámicos, FCEIA-UNR, IFIR-CONICET, Pellegrini 250, Rosario S2000BTP (Argentina)

    2014-10-01

    Here we describe the development of novel nanostructured coating systems with improved photocatalytic and antibacterial activities. These systems comprise a layer of SiO{sub 2} followed by a layer of mesoporous or dense TiO{sub 2}-anatase, and doping with silver nanoparticles (Ag NPs). The coatings were synthesized via a sol–gel technique by combining colloidal Ag NPs with TiO{sub 2} and SiO{sub 2} sols. The photocatalytic activity was studied through methyl orange decomposition under UV light. Results showed a great increase of photocatalytic activity by Ag NPs doping. The most active photocatalyst corresponded to the Ag–SiO{sub 2}/TiO{sub 2} mesoporous system, associated with the porosity of the coatings and with the decrease of e–h recombination for the presence of Ag NPs. All the TiO{sub 2} coatings showed a strong bactericidal activity against planktonic forms of Gram-negative (enterohemorrhagic Escherichia coli) and Gram-positive (Listeria monocytogenes) pathogens, as well as a strong germicidal effect against deadly spores of human gas gangrene- and anthrax-producing bacteria (Clostridium perfringens and Bacillus anthracis, respectively). The bactericidal and sporocidal activity was improved by doping the coatings with Ag NPs, even more when nanoparticles were in the outer layer of TiO{sub 2}, because they are more accessible to the environment. The mechanisms responsible for the increase of photocatalytic and bactericidal behaviors related to Ag NP doping were studied by spectroscopic ellipsometry, UV–vis spectroscopy, photoluminescence and anodic stripping voltammetry. It was found that the separation of the electron–hole pair contributed to the enhancement of photocatalysis, whereas the effect of the local electric field reinforcement was probably present. A possible involvement of a decrease of band-gap energy and dispersion by silver nanoparticles is ruled out. bactericidal efficacy was increased by Ag{sup +} ion release. Overall, the results

  9. An Eiganstrain Analysis of Mechanical Properties of Nanostructured Ceramic Coatings by Synchrotron Probe

    Science.gov (United States)

    2010-06-01

    features are shown on an expanded scale in the inset of the figure. Comparison of the n- and µ-feed powder spectra are to the anatase phase TiO2...dramatically differend and are unambiguously not anatase phase. Note that the FS oscillations above the edge are sharper for the µ-PS- coating (relative to the

  10. Adhesion to Y-TZP ceramic: study of silica nanofilm coating on the surface of Y-TZP.

    Science.gov (United States)

    Druck, Carolina Ceolin; Pozzobon, João Luiz; Callegari, Gustavo Luiz; Dorneles, Lucio Strazzabosco; Valandro, Luiz Felipe

    2015-01-01

    This study evaluated the influence of silica-based film coatings on the surface of yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP), in particular on the durability of the bond strength between the ceramic and resin cement. Eighty Y-TZP (In-Ceram YZ, Vita) blocks (4 × 4 × 3 mm) were obtained and divided into four groups according to the surface treatments (n = 20): tribochemical silica coating (TBS; Cojet, 3M/ESPE), 5 nm SiO2 nanofilm and silanization (F-5), 500 nm SiO2 nanofilm and silanization (F-500), and 500 nm SiO2 nanofilm + hydrofluoric-acid-etching + silanization (F-500HF). Specimens of composite resin (3.25 mm in diameter and 3 mm in height) were cemented to Y-TZP blocks using resin cement (Relyx ARC). Half of the specimens from each group were tested 24 h after adhesion (B: baseline condition), and the other half were subjected to aging (A: storage for 90 days and 10,000 thermal cycles). The specimens were subjected to shear testing (SBS) (1 mm/min). After testing, the surfaces were analyzed with a stereomicroscope and scanning electron microscope. Micromorphologic and elemental chemical analyses of the treated Y-TZP surface were made by X-ray energy dispersive spectroscopy. Bond strength data were statistically analyzed by Kruskal-Wallis/Mann-Whitney tests (α = 0.05). The surface treatment showed significant differences for B (p = 0.0001) and A (p = 0.0000) conditions. In both storage conditions, TBS and F-5 groups promoted the significantly highest bond strength. Most of the specimens presented adhesive failure. The X-ray energy dispersive spectroscopy analysis depicted the highest peak of silica in the TBS, F-5, and F-500 groups. The adhesion to zirconia can be improved if the surface receives a 5 nm layer of SiO2 nanofilm or is subjected to sandblasting with silica particles, followed by silanization.

  11. 氮化钛/氧化钛复相陶瓷涂层的干滑动摩擦磨损性能%Dry Sliding Wear and Friction Performance of TiN/TiO Composite Ceramic Coating

    Institute of Scientific and Technical Information of China (English)

    夏铭; 王泽华; 周泽华; 胡亚群; 邵佳; 盛欢

    2015-01-01

    Objective To study the microstructure, microhardness as well as dry sliding wear and friction behavior and mecha-nism of plasma sprayed TiN/TiO composite ceramic coating under different conditions. Methods TiN/TiO ceramic coating was pre-pared on 45# steel by reactive plasma spraying technology. Phase composition of the coating was analyzed using X-ray diffraction ( XRD) and the microhardness was measured by a hardness tester. The wear and friction behavior of TiN/TiO composite ceramic coating was studied through wear and friction tests, the wear and friction morphology was observed, the composition of the wear sur- face was tested, and the wear mechanism of TiN/TiO composite ceramic coating was discussed. Results The coating was even and dense with obvious layered structure and an average thickness of 350 μm. The porosity of the coating was 4. 3% and the hardness was 1444HV0. 1. Under the conditions of rotational speed at 370 to 1102 r/min and load at 30 to 50 N, the friction coefficient ranged from 0. 0963 to 0. 2778 and the wear mass loss was from 1. 32 to 6. 8 mg. Besides, the friction coefficient decreased with in-creasing load while the wear mass loss of the coated samples had an increasing trend with the increasing load and rotational speed. Conclusion The coating prepared by plasma spraying was dense with high microhardness. When the load and rotational speed were low, it had excellent wear resistance. However, the wear resistance decreased with increasing load and rotational speed. The main wear mechanisms of the coating were abrasive wear and adhesive wear.%目的 研究等离子喷涂TiN/TiO复相陶瓷涂层的微观组织结构、显微硬度及干滑动摩擦磨损行为和机理. 方法 采用等离子喷涂技术,在45 #钢表面制备TiN/TiO复相陶瓷涂层. 分析涂层的相组成,测试涂层的硬度. 通过磨损试验研究TiN/TiO复相陶瓷涂层的磨损行为,并观察涂层的磨损形貌,测试磨损表面的成分组成,探讨TiN/Ti

  12. TEMPERATURE DISTRIBUTION IN MULTILAYER METAL-CERAMIC COATINGS UNDER NONSTATIONARY THERMAL EFFECTS

    Directory of Open Access Journals (Sweden)

    Vasiliy M. Samoilenko

    2017-01-01

    Full Text Available Progress in the aircraft engine construction is determined by the increase of operation parameters of gas turbine engines, which is inevitably accompanied by an increase of operating temperatures and load for the vital elements of the turbine hot ducts. Furthermore, the requirements for reliability of the engine in general are also increasing. Achievement of these requirements is determined by the performance of the materials turbine blades are made of and is made possible by the application of high-heat Nickel alloys in combination with combined heat-shielding coatings.This article dwells on the problem of assessing the impact of non-stationary thermal effects on the temperature distribution in a multilayer heatproof coating. With the aim of assessing the working capacity of heatproof coatings we propose a method of calculating the temperature field for the blade profile and the coatingdepth, based on the solution of the basic one-dimensional differential equation of heat conduction.This method allows us to assess the performance of heatproof coating and also gives us an opportunity to choose a combination of heatproof coating layers for the specific operating conditions of a gas turbine engine’s blades.In addition, using the proposed method it is possible to evaluate the effect of non-stationary heat flux on the structure of high-temperature alloy of the engine’s turbine blades and, therefore, to evaluate the capacity with the given coating. At temperatures of 1150–1200 °C and higher in heat-resistant Nickel alloys there starts a coagulation process of the main reinforcing coherent particle phase on the basis of the intermetallic compound, long plates with wavy shapes are formed instead of the cuboids, a formation of topologically close-packed phases which are needle-like compositions happens. These processes lead to a significant deterioration of the strength characteristics of heat-resistant alloys. Making calculations according to

  13. NASA's Advanced Environmental Barrier Coatings Development for SiC/SiC Ceramic Matrix Composites: Understanding Calcium Magnesium Alumino-Silicate (CMAS) Degradations and Resistance

    Science.gov (United States)

    Zhu, Dongming

    2014-01-01

    Environmental barrier coatings (EBCs) and SiCSiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures with improved efficiency, reduce engine weight and cooling requirements. The development of prime-reliant environmental barrier coatings is essential to the viability and reliability of the envisioned CMC engine component applications, ensuring integrated EBC-CMC system durability and designs are achievable for successful applications of the game-changing component technologies and lifing methodologies.This paper will emphasize recent NASA environmental barrier coating developments for SiCSiC turbine airfoil components, utilizing advanced coating compositions, state-of-the-art processing methods, and combined mechanical and environment testing and durability evaluations. The coating-CMC degradations in the engine fatigue-creep and operating environments are particularly complex; one of the important coating development aspects is to better understand engine environmental interactions and coating life debits, and we have particularly addressed the effect of Calcium-Magnesium-Alumino-Silicate (CMAS) from road sand or volcano-ash deposits on the durability of the environmental barrier coating systems, and how the temperature capability, stability and cyclic life of the candidate rare earth oxide and silicate coating systems will be impacted in the presence of the CMAS at high temperatures and under simulated heat flux conditions. Advanced environmental barrier coating systems, including HfO2-Si with rare earth dopant based bond coat systems, will be discussed for the performance improvements to achieve better temperature capability and CMAS resistance for future engine operating conditions.

  14. Development of Detonation Flame Sprayed Cu-Base Coatings Containing Large Ceramic Particles

    Science.gov (United States)

    Tillmann, Wolfgang; Vogli, Evelina; Nebel, Jan

    2007-12-01

    Metal-matrix composites (MMCs) containing large ceramic particles as superabrasives are typically used for grinding stone, minerals, and concrete. Sintering and brazing are the key manufacturing technologies for grinding tool production. However, restricted geometry flexibility and the absence of repair possibilities for damaged tool surfaces, as well as difficulties of controlling material interfaces, are the main weaknesses of these production processes. Thermal spraying offers the possibility to avoid these restrictions. The research for this paper investigated a fabrication method based on the use of detonation flame spraying technology to bond large superabrasive particles (150-600 μm, needed for grinding minerals and stones) in a metallic matrix. Layer morphology and bonding quality are evaluated with respect to superabrasive material, geometry, spraying, and powder-injection parameters. The influence of process temperature and the possibilities of thermal treatment of MMC layers are analyzed.

  15. Life Prediction Issues in Thermal/Environmental Barrier Coatings in Ceramic Matrix Composites

    Science.gov (United States)

    Shah, Ashwin R.; Brewer, David N.; Murthy, Pappu L. N.

    2001-01-01

    Issues and design requirements for the environmental barrier coating (EBC)/thermal barrier coating (TBC) life that are general and those specific to the NASA Ultra-Efficient Engine Technology (UEET) development program have been described. The current state and trend of the research, methods in vogue related to the failure analysis, and long-term behavior and life prediction of EBCITBC systems are reported. Also, the perceived failure mechanisms, variables, and related uncertainties governing the EBCITBC system life are summarized. A combined heat transfer and structural analysis approach based on the oxidation kinetics using the Arrhenius theory is proposed to develop a life prediction model for the EBC/TBC systems. Stochastic process-based reliability approach that includes the physical variables such as gas pressure, temperature, velocity, moisture content, crack density, oxygen content, etc., is suggested. Benefits of the reliability-based approach are also discussed in the report.

  16. Characterization of Er{sub 2}O{sub 3} ceramic coatings by luminescence measurements

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, T., E-mail: teru@nifs.ac.jp [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, Gifu 509-5292 (Japan); Yoshino, M. [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan); Hishinuma, Y. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, Gifu 509-5292 (Japan); Zhang, D. [School of Physical Sciences, The Graduate University for Advanced Studies, 322-6 Oroshi-cho, Toki, Gifu 509-5292 (Japan); Kada, W. [Department of Advanced Radiation Technology, Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki-shi, Gunma 370-1292 (Japan); Sato, F.; Iida, T. [Graduate School of Engineering, Osaka University, 2-1 Yamada-Oka, Suita, Osaka 565-0871 (Japan); Nagasaki, T. [EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan); Muroga, T. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, Gifu 509-5292 (Japan)

    2011-10-01

    Cathodoluminescence and ion beam induced luminescence measurements were performed on Er{sub 2}O{sub 3} coatings fabricated by the Metal Organic Chemical Vapor Deposition (MOCVD), Metal Organic Decomposition (MOD) and RF sputtering methods to examine relations between luminescence spectra and their crystallinities. In luminescence spectra of all the measurements, peaks were observed in three bands of 380-420 nm, 530-580 nm and 640-690 nm. Cathodoluminescence intensities in the band of 640-690 nm increased with substrate temperatures in the fabrication processes and are considered to be significantly sensitive to the crystallinity. Change in luminescence spectra under ion beam irradiations also supported the relation. By using the relations between the spectra and crystallinities, luminescence measurements would be effective for nondestructive inspection and analysis of Er{sub 2}O{sub 3} coatings with a high spatial resolution.

  17. Effect of silver nanoparticle coatings on mycobacterial biofilm attachment and growth: Implications for ceramic water filters

    Science.gov (United States)

    Larimer, Curtis James

    Silver is a natural, broad-spectrum antibacterial metal and its toxicity can be enhanced when surface area is maximized. As a result, silver nanoparticles (AgNP) have been investigated for use in novel water treatment technologies. The hypothesis of this work is that deposited AgNPs can enhance water treatment technologies by inhibiting growth of planktonic bacteria and biofilms. This was investigated by evaluating the antibacterial efficacy of AgNPs both in solution and as deposited on surfaces. AgNPs were found to be toxic to three species of environmental mycobacteria, M. smegmatis, M. avium, and M. marinum and the level of susceptibility varied widely, probably owing to the varying levels of silver that each species is exposed to in its natural environment. When cultured in a AgNP enriched environment M. smegmatis developed resistance to the toxic effects of both the nanoparticles and silver ions. The resistant mutant was as viable as the unmodified strain and was also resistant to antibiotic isoniazid. However, the strain was more susceptible to other toxic metal ions from ZnSO4 and CuSO4. AgNPs were deposited on silicon wafer substrates by vertical colloidal deposition (VCD). Manipulating deposition speed and also concentration of AgNPs in the depositing liquid led to a range of AgNP coatings with distinctive deposition lines perpendicular to the motion of the meniscus. Experimental results for areal coverage, which was measured from SEM images of AgNP coatings, were compared to Diao's theory of VCD but did not show agreement due to a stick-slip mechanism that is not accounted for by the theory. Durability of AgNP coatings is critical for antibacterial efficacy and to mitigate the risks of exposing the environment to nanomaterials and it was measured by exposing AgNP coatings to liquid flow in a flow cell. Durability was improved by modifying processing to include a heat treatment after deposition. Finally, the antibiofilm efficacy of deposited AgNPs was

  18. Preparation and properties of nanophase (Ce, Zr, PrO2-doped alumina coating on cordierite ceramic honeycomb for three-way catalysts

    Directory of Open Access Journals (Sweden)

    Jiuying Tian

    2012-03-01

    Full Text Available Nanophase (Ce, Zr, PrO2-doped alumina coatings were prepared by impregnating the cordierite ceramic honeycomb in the sol or in the slurry of already calcined powder, respectively. The effects of preparation methods on the crystal phase, texture, oxygen storage capacity (OSC, reducibility, surface morphology and thermal stability of coatings were investigated by X-ray diffraction (XRD, the Brunauer Emmet Teller (BET method, the oxygen pulsing technique, H2-temperature-programmed reduction (H2-TPR and scanning electron microscopy (SEM. These nanophase (Ce, Zr, PrO2-doped alumina coatings were used as supports to prepare Pd-only three-way catalysts, and evaluated with respect to catalytic activities. The results indicate that the nanophase (Ce, Zr, PrO2-doped alumina coatings prepared by the two methods have high thermal stability. However, the coating derived from the sol shows better crystalline structure, texture, reducibility and oxygen storage capacity than the coating derived from the slurry. SEM observation shows that the morphology of the coating derived from the sol is uniform and smooth. The Pd-only catalyst derived from the sol exhibits high three-way catalytic activity at low temperature and thermal stability, suggesting a great potential for applications.

  19. Preparation and properties of nanophase (Ce, Zr, Pr)O{sub 2}-doped alumina coating on cordierite ceramic honeycomb for three-way catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Jiuying; Lu, Jusheng [School of Chemistry and Chemical Engineering, Jiangsu Key Laboratory of Green Synthetic Chemistry for Functional Materials, Xuzhou Normal University, Xuzhou P.R. (China)

    2012-01-15

    Nanophase (Ce, Zr, Pr)O{sub 2}-doped alumina coatings were prepared by impregnating the cordierite ceramic honeycomb in the sol or in the slurry of already calcined powder, respectively. The effects of preparation methods on the crystal phase, texture, oxygen storage capacity (OSC), reducibility, surface morphology and thermal stability of coatings were investigated by X-ray diffraction (XRD), the Brunauer Emmet Teller (BET) method, the oxygen pulsing technique, H2-temperature-programmed reduction (H2-TPR) and scanning electron microscopy (SEM). These nanophase (Ce, Zr, Pr)O{sub 2}-doped alumina coatings were used as supports to prepare Pd-only three-way catalysts, and evaluated with respect to catalytic activities. The results indicate that the nanophase (Ce, Zr, Pr)O{sub 2}-doped alumina coatings prepared by the two methods have high thermal stability. However, the coating derived from the sol shows better crystalline structure, texture, reducibility and oxygen storage capacity than the coating derived from the slurry. SEM observation shows that the morphology of the coating derived from the sol is uniform and smooth. The Pd-only catalyst derived from the sol exhibits high three-way catalytic activity at low temperature and thermal stability, suggesting a great potential for applications. (author)

  20. Characterization of bioactive ceramic coatings prepared on titanium implants by micro-arc oxidation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Micro-arc oxidation (MAO) is an enhanced chemical technology in an electrolyte medium to obtain coating structures on valve-metal surfaces. Titanium oxide films obtained by MAO in the sodium phosphate electrolyte were investigated. The films were composed mainly of TiO2 phases in the form of anatase and rutile and enriched with Na and P elements at the surface. Their apatite-inducing ability was evaluated in a simulated body fluid (SBF). When immersing in SBF for over 30 d, a preferential carbonated-hydroxyapatite was formed on the surfaces of the films, which suggests that the MAO-treated titanium has a promising positive biological response.

  1. 陶瓷涂层三明治板的抗热震性%THERMAL SHOCK RESISTANCE OF THE CERAMIC COATED SANDWICH PLATE

    Institute of Scientific and Technical Information of China (English)

    李艳征; 赵军; 艾兴

    2008-01-01

    采用解析法研究了第3类边界条件下双面陶瓷涂层三明治板的瞬态温度场及瞬态热应力场.对不同Biot模数的热冲击过程中,Al2O3涂层/硬质合金(WC-8%Co,质量分数)基体/Al2O3涂层三明治板的瞬态热应力进行了数值计算.分析了涂层/基体厚度比、涂层与基体热-物理性能匹配对陶瓷涂层三明治板表面热应力峰值的影响.结果表明:陶瓷涂层三明治板的基体的热导率、线膨胀系数和弹性模量应高于涂层,这样可以降低其表面热应力,获得高抗热震性陶瓷涂层三明治板.此外,涂层厚度应尽可能小,以利于改善涂层的抗热震性.%The transient temperature field and transient thermal stress field of a sandwich plate with double-sided ceramic coatings under the convective boundary condition were investigated by an analytical solution approach. Numerical calculations of transient thermal stresses for a plate of Al2O3 coating/ cemented carbide (WC-8%Co, mass fraction) substrate/Al2O3 coating system under different Biot numbers in thermal shock were performed. The effects of the coating-to-substrate thickness ratio and the thermo-physical properties matching of coating with substrate on the peak surface thermal stress of the ceramic coated sandwich plate were analyzed. The results reveal that the thermal conductivity, thermal expansion coefficient and Young's modulus of the substrate must be higher than that of the coating in the coated sandwich plate in order to reduce its surface thermal stress and obtain high thermal shock resistance. Furthermore, the coating must be as thin as possible in order to improve the thermal shock resistance of the coating on the surface of the coated cutting tools.

  2. Development of wear resistant ceramic coatings for diesel engine components. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Haselkorn, M.H. [Caterpillar, Inc., Peoria, IL (United States)

    1992-04-01

    Improved fuel economy and a reduction of emissions can be achieved by insulation of the combustion chamber components to reduce heat rejection. However, insulating the combustion chamber components will also increase the operating temperature of the piston ring/cylinder liner interface from approximately 150{degree}C to over 300{degree}C. Existing ring/liner materials can not withstand these higher operating temperatures and for this reason, new materials need to be developed for this critical tribological interface. The overall goal of this program is the development of piston ring/cylinder liner material pairs which would be able to provide the required friction and wear properties at these more severe operating conditions. More specifically, this program first selected, and then evaluated, potential d/wear resistant coatings which could be applied to either piston rings an or cylinder liners and provide, at 350{degree}C under lubricated conditions, coefficients of friction below 0.1 and wear rates of less than 25 {times} lO{sup {minus}6} mm/hour. The processes selected for applying the candidate wear resistant coatings to piston rings and/or cylinder liners were plasma spraying, chemical vapor, physical vapor and low temperature arc vapor deposition techniques as well as enameling techniques.

  3. Biomimetic component coating on 3D scaffolds using high bioactivity of mesoporous bioactive ceramics

    Directory of Open Access Journals (Sweden)

    Yun HS

    2011-10-01

    Full Text Available Hui-suk Yun1, Sang-Hyun Kim2, Dongwoo Khang3, Jungil Choi4, Hui-hoon Kim2, Minji Kang31Functional Materials Division, Korea Institute of Materials Science, Gyeongnam, Korea; 2Department of Pharmacology, School of Medicine, Kyungpook National University, Jung-Gu, Daegu, Korea; 3School of Nano and Advanced Materials Science and Engineering and Center for NMBE, Gyeongsang National University, Jinju, Korea; 4Department of Anatomy, Institute of Health Science and School of Medicine, Gyeongsang National University, Jinju, Gyeongnam, KoreaBackground: Mesoporous bioactive glasses (MBGs are very attractive materials for use in bone tissue regeneration because of their extraordinarily high bone-forming bioactivity in vitro. That is, MBGs may induce the rapid formation of hydroxy apatite (HA in simulated body fluid (SBF, which is a major inorganic component of bone extracellular matrix (ECM and comes with both good osteoconductivity and high affinity to adsorb proteins. Meanwhile, the high bioactivity of MBGs may lead to an abrupt initial local pH variation during the initial Ca ion-leaching from MBGs at the initial transplant stage, which may induce unexpected negative effects on using them in in vivo application. In this study we suggest a new way of using MBGs in bone tissue regeneration that can improve the strength and make up for the weakness of MBGs. We applied the outstanding bone-forming bioactivity of MBG to coat the main ECM components HA and collagen on the MBG-polycarplolactone (PCL composite scaffolds for improving their function as bone scaffolds in tissue regeneration. This precoating process can also expect to reduce initial local pH variation of MBGs.Methods and materials: The MBG-PCL scaffolds were immersed in the mixed solution of the collagen and SBF at 37°C for 24 hours. The coating of ECM components on the MBG-PCL scaffolds and the effect of ECM coating on in vitro cell behaviors were confirmed.Results: The ECM components were fully

  4. Modification of the structure and composition of Ca10(PO4)6(OH)2 ceramic coatings by changing the deposition conditions in O2 and Ar

    Science.gov (United States)

    Donkov, N.; Zykova, A.; Safonov, V.; Kolesnikov, D.; Goncharov, I.; Yakovin, S.; Georgieva, V.

    2014-05-01

    Hydroxyapatite Ca10(PO4)6(OH)2 (HAp) is a material considered to be used to form structural matrices in the mineral phase of bone, dentin and enamel. HAp ceramic materials and coatings are widely applied in medicine and dentistry because of their ability to increase the tissue response to the implant surface and promote bone ingrowth and osseoconduction processes. The deposition conditions affect considerably the structure and bio-functionality of the HAp coatings. We focused our research on developing deposition methods allowing a precise control of the structure and stoichiometric composition of HAp thin films. We found that the use of O2 as a reactive gas improves the quality of the sputtered hydroxyapatite coatings by resulting in the formation of films of better stoichiometry with a fine crystalline structure.

  5. Bactericidal activities of woven cotton and nonwoven polypropylene fabrics coated with hydroxyapatite-binding silver/titanium dioxide ceramic nanocomposite "Earth-plus"

    Directory of Open Access Journals (Sweden)

    Kasuga E

    2011-09-01

    Full Text Available Eriko Kasuga1,2, Yoshiyuki Kawakami2,3, Takehisa Matsumoto1, Eiko Hidaka1, Kozue Oana2, Naoko Ogiwara1, Dai Yamaki4, Tsukasa Sakurada4, Takayuki Honda1,51Department of Laboratory Medicine, Shinshu University Hospital, 2Division of Infection Control and Microbiological Regulation, Department of Health and Medical Sciences, Shinshu University Graduate School of Medicine, 3Division of Clinical Microbiology, Department of Biomedical Laboratory Sciences, School of Health Sciences, Shinshu University School of Medicine, 4Shinshu Ceramics Co Ltd, Kiso, Nagano, Japan; 5Department of Laboratory Medicine, Shinshu University School of Medicine, Matsumoto, JapanBackground: Bacteria from the hospital environment, including linens and curtains, are often responsible for hospital-associated infections. The aim of the present study was to evaluate the bactericidal effects of fabrics coated with the hydroxyapatite-binding silver/titanium dioxide ceramic nanocomposite "Earth-plus".Methods: Bactericidal activities of woven and nonwoven fabrics coated with Earth-plus were investigated by the time-kill curve method using nine bacterial strains, including three Staphylococcus aureus, three Escherichia coli, and three Pseudomonas aeruginosa strains.Results: The numbers of viable S. aureus and E. coli cells on both fabrics coated with Earth-plus decreased to below 2 log10 colony-forming units/mL in six hours and reached the detection limit in 18 hours. Viable cell counts of P. aeruginosa on both fabrics coated with Earth-plus could not be detected after 3–6 hours. Viable cells on woven fabrics showed a more rapid decline than those on nonwoven fabrics. Bacterial cell counts of the nine strains on fabrics without Earth-plus failed to decrease even after 18 hours.Conclusion: Woven cotton and nonwoven polypropylene fabrics were shown to have excellent antibacterial potential. The woven fabric was more bactericidal than the nonwoven fabric.Keywords: hydroxyapatite

  6. Dense CdS thin films on fluorine-doped tin oxide coated glass by high-rate microreactor-assisted solution deposition

    Energy Technology Data Exchange (ETDEWEB)

    Su, Yu-Wei, E-mail: suyuweiwayne@gmail.com [School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR 97330 (United States); Microproducts Breakthrough Institute and Oregon Process Innovation Center, Corvallis, Oregon 97330 (United States); Ramprasad, Sudhir [Energy Processes and Materials Division, Pacific Northwest National Laboratory, Corvallis, OR 9730 (United States); Microproducts Breakthrough Institute and Oregon Process Innovation Center, Corvallis, Oregon 97330 (United States); Han, Seung-Yeol; Wang, Wei [School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR 97330 (United States); Microproducts Breakthrough Institute and Oregon Process Innovation Center, Corvallis, Oregon 97330 (United States); Ryu, Si-Ok [School of Display and Chemical Engineering, Yeungnam University, 214-1 Dae-dong, Gyeonsan, Gyeongbuk 712-749 (Korea, Republic of); Palo, Daniel R. [Barr Engineering Co., Hibbing, MN 55747 (United States); Paul, Brian K. [School of Mechanical, Industrial and Manufacturing Engineering, Oregon State University, Corvallis, OR 97330 (United States); Microproducts Breakthrough Institute and Oregon Process Innovation Center, Corvallis, Oregon 97330 (United States); Chang, Chih-hung [School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR 97330 (United States); Microproducts Breakthrough Institute and Oregon Process Innovation Center, Corvallis, Oregon 97330 (United States)

    2013-04-01

    Continuous microreactor-assisted solution deposition is demonstrated for the deposition of CdS thin films on fluorine-doped tin oxide (FTO) coated glass. The continuous flow system consists of a microscale T-junction micromixer with the co-axial water circulation heat exchanger to control the reacting chemical flux and optimize the heterogeneous surface reaction. Dense, high quality nanocrystallite CdS thin films were deposited at an average rate of 25.2 nm/min, which is significantly higher than the reported growth rate from typical batch chemical bath deposition process. Focused-ion-beam was used for transmission electron microscopy specimen preparation to characterize the interfacial microstructure of CdS and FTO layers. The band gap was determined at 2.44 eV by UV–vis absorption spectroscopy. X-ray photon spectroscopy shows the binding energies of Cd 3d{sub 3/2}, Cd 3d{sub 5/2}, S 2P{sub 3/2} and S 2P{sub 1/2} at 411.7 eV, 404.8 eV, 162.1 eV and 163.4 eV, respectively. - Highlights: ► CdS films deposited using continuous microreactor-assisted solution deposition (MASD) ► Dense nanocrystallite CdS films can be reached at a rate of 25.2 [nm/min]. ► MASD can approach higher film growth rate than conventional chemical bath deposition.

  7. Microstructure and Wear Behaviour of Laser-Induced Thermite Reaction Al2O3 Ceramic Coatings on Pure Aluminum and AA7075 Aluminum Alloy

    Institute of Scientific and Technical Information of China (English)

    HUANG Kaijin; LIN Xin; XIE Changsheng; T M Yue

    2008-01-01

    Wear-resistant laser-induced thermite reaction Al2O3 ceramic coatings can be fabricated on pure Al and AA7075 aluminum alloy by laser cladding(one-step method)and laser cladding followed by laser re-melting(two-step method)using mixed powders CuO-Al-SiO2 in order to improve the wear properties of aluminum and aluminum alloy,respectively.The microstructure of the coatings was characterized by scanning electron microscopy(SEM)and X-ray diffraction(XRD).The wear resistance of the coatings was evaluated under dry sliding wear test condition at room temperature.Owing to the presence of hard a-Al2O3 and γ-Al2O,3phases,the coatings exhibited excellent wear resistance.In addition,the wear resistance of the coatings fabricated by two-step method is superior to that of the coatings fabricated by one-step method.

  8. Sol-gel dip coating of yttria-stabilized tetragonal zirconia dental ceramic by aluminosilicate nanocomposite as a novel technique to improve the bonding of veneering porcelain.

    Science.gov (United States)

    Madani, Azamsadat; Nakhaei, Mohammadreza; Karami, Parisa; Rajabzadeh, Ghadir; Salehi, Sahar; Bagheri, Hossein

    2016-01-01

    The aim of this in vitro study was to evaluate the effect of silica and aluminosilicate nanocomposite coating of zirconia-based dental ceramic by a sol-gel dip-coating technique on the bond strength of veneering porcelain to the yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) in vitro. Thirty Y-TZP blocks (10 mm ×10 mm ×3 mm) were prepared and were assigned to four experimental groups (n=10/group): C, without any further surface treatment as the control group; S, sandblasted using 110 μm alumina powder; Si, silica sol dip coating + calcination; and Si/Al, aluminosilicate sol dip coating + calcination. After preparing Y-TZP samples, a 3 mm thick layer of the recommended porcelain was fired on the coated Y-TZP surface. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis were used to characterize the coating and the nature of the bonding between the coating and zirconia. To examine the zirconia-porcelain bond strength, a microtensile bond strength (μTBS) approach was chosen. FT-IR study showed the formation of silica and aluminosilicate materials. XRD pattern showed the formation of new phases consisting of Si, Al, and Zr in coated samples. SEM showed the formation of a uniform coating on Y-TZP samples. Maximum μTBS values were obtained in aluminosilicate samples, which were significantly increased compared to control and sandblasted groups (P=0.013 and Pporcelain.

  9. Cu{sub 1.5}Mn{sub 1.5}O{sub 4}-based ceramic spectrally selective coatings for efficient solar absorber applications

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Pengjun [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); University of Chinese Academy of Sciences, Beijing, 100049 (China); Geng, Qingfen; Gao, Xianghu [Research & Development Center for Eco-material and Eco-chemistry, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); Yang, Shengrong [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); Liu, Gang, E-mail: gangliu@licp.cas.cn [Research & Development Center for Eco-material and Eco-chemistry, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China)

    2016-08-05

    Cu{sub 1.5}Mn{sub 1.5}O{sub 4}-based ceramic spectrally selective (CSS) coating was deposited on aluminum substrate using a sol–gel dip-coating method. The citric acid introduced in the precursor system lowered the required calcining temperature of crystalline Cu{sub 1.5}Mn{sub 1.5}O{sub 4}. X-Ray diffraction (XRD) peaks of coatings annealed above 450 °C were found to coincide exactly with that of crystalline Cu{sub 1.5}Mn{sub 1.5}O{sub 4} in JCPDS database. By optimizing the withdrawal rate and calcining temperature, coating with spectral selectivity as good as α{sub s} = 0.876 and ε{sub 100} = 0.057 was achieved after only one dipping/annealing cycle. Subjected to an accelerated ageing test at 259 °C, the obtained CSS coating showed an excellent thermally durability with the performance criterion (PC) values below 0.05. - Highlights: • Cu{sub 1.5}Mn{sub 1.5}O{sub 4}-based CSS coating is achieved after only one dipping/annealing cycle. • Cu{sub 1.5}Mn{sub 1.5}O{sub 4} coating is obtained as the annealing temperature reaches to 450 °C. • Cu{sub 1.5}Mn{sub 1.5}O{sub 4} coating exhibits optical parameter: α{sub s} = 0.876 and ε{sub 100} = 0.057. • Cu{sub 1.5}Mn{sub 1.5}O{sub 4} coating shows the excellent stability in low to mid temperature region.

  10. Organosilane-Based Coating of Quartz Species from the Traditional Ceramics Industry: Evidence of Hazard Reduction Using In Vitro and In Vivo Tests.

    Science.gov (United States)

    Ziemann, Christina; Escrig, Alberto; Bonvicini, Giuliana; Ibáñez, Maria Jesús; Monfort, Eliseo; Salomoni, Arturo; Creutzenberg, Otto

    2017-02-28

    The exposure to respirable crystalline silica (RCS), e.g. quartz, in industrial settings can induce silicosis and may cause tumours in chronic periods. Consequently, RCS in the form of quartz and cristobalite has been classified as human lung carcinogen category 1 by the International Agency for Research on Cancer in 1997, acknowledging differences in hazardous potential depending on source as well as chemical, thermal, and mechanical history. The physico-chemical determinants of quartz toxicity are well understood and are linked to density and abundance of surface silanol groups/radicals. Hence, poly-2-vinylpyridine-N-oxide and aluminium lactate, which effectively block highly reactive silanol groups at the quartz surface, have formerly been introduced as therapeutic approaches in the occupational field. In the traditional ceramics industry, quartz-containing raw materials are indispensable for the manufacturing process, and workers are potentially at risk of developing quartz-related lung diseases. Therefore, in the present study, two organosilanes, i.e. Dynasylan® PTMO and Dynasylan® SIVO 160, were tested as preventive, covalent quartz-coating agents to render ceramics production safer without loss in product quality. Coating effectiveness and coating stability (up to 1 week) in artificial alveolar and lysosomal fluids were first analysed in vitro, using the industrially relevant quartz Q1 as RCS model, quartz DQ12 as a positive control, primary rat alveolar macrophages as cellular model system (75 µg cm-2; 4 h of incubation ± aluminium lactate to verify quartz-related effects), and lactate dehydrogenase release and DNA strand break induction (alkaline comet assay) as biological endpoints. In vitro results with coated quartz were confirmed in a 90-day intratracheal instillation study in rats with inflammatory parameters as most relevant readouts. The results of the present study indicate that in particular Dynasylan® SIVO 160 (0.2% w/w of quartz) was able

  11. Heat treatment following surface silanization in rebonded tribochemical silica-coated ceramic brackets: shear bond strength analysis

    Science.gov (United States)

    SILVA, Emilia Adriane; TRINDADE, Flávia Zardo; RESKALLA, Hélcio Nagib José Feres; de QUEIROZ, José Renato Cavalcanti

    2013-01-01

    Objective This study aimed to evaluate the effects of heat treatment on the tribochemical silica coating and silane surface conditioning and the bond strength of rebonded alumina monocrystalline brackets. Material and Methods Sixty alumina monocrystalline brackets were randomly divided according to adhesive base surface treatments (n=20): Gc, no treatment (control); Gt, tribochemical silica coating + silane application; Gh, as per Gt + post-heat treatment (air flux at 100ºC for 60 s). Brackets were bonded to the enamel premolars surface with a light-polymerized resin and stored in distilled water at 37ºC for 100 days. Additionally, half the specimens of each group were thermocycled (6,000 cycles between 5-55ºC) (TC). The specimens were submitted to the shear bond strength (SBS) test using a universal testing machine (1 mm/min). Failure mode was assessed using optical and scanning electron microscopy (SEM), together with the surface roughness (Ra) of the resin cement in the bracket using interference microscopy (IM). 2-way ANOVA and the Tukey test were used to compare the data (p>0.05). Results The strategies used to treat the bracket surface had an effect on the SBS results (p=0.0), but thermocycling did not (p=0.6974). Considering the SBS results (MPa), Gh-TC and Gc showed the highest values (27.59±6.4 and 27.18±2.9) and Gt-TC showed the lowest (8.45±6.7). For the Ra parameter, ANOVA revealed that the aging method had an effect (p=0.0157) but the surface treatments did not (p=0.458). For the thermocycled and non-thermocycled groups, Ra (µm) was 0.69±0.16 and 1.12±0.52, respectively. The most frequent failure mode exhibited was mixed failure involving the enamel-resin-bracket interfaces. Conclusion Regardless of the aging method, Gh promoted similar SBS results to Gc, suggesting that rebonded ceramic brackets are a more effective strategy. PMID:24037072

  12. Heat treatment following surface silanization in rebonded tribochemical silica-coated ceramic brackets: shear bond strength analysis

    Directory of Open Access Journals (Sweden)

    Emilia Adriane Silva

    2013-07-01

    Full Text Available OBJECTIVE: This study aimed to evaluate the effects of heat treatment on the tribochemical silica coating and silane surface conditioning and the bond strength of rebonded alumina monocrystalline brackets. MATERIAL AND METHODS: Sixty alumina monocrystalline brackets were randomly divided according to adhesive base surface treatments (n=20: Gc, no treatment (control; Gt, tribochemical silica coating + silane application; Gh, as per Gt + post-heat treatment (air flux at 100ºC for 60 s. Brackets were bonded to the enamel premolars surface with a light-polymerized resin and stored in distilled water at 37ºC for 100 days. Additionally, half the specimens of each group were thermocycled (6,000 cycles between 5-55ºC (TC. The specimens were submitted to the shear bond strength (SBS test using a universal testing machine (1 mm/min. Failure mode was assessed using optical and scanning electron microscopy (SEM, together with the surface roughness (Ra of the resin cement in the bracket using interference microscopy (IM. 2-way ANOVA and the Tukey test were used to compare the data (p>0.05. RESULTS: The strategies used to treat the bracket surface had an effect on the SBS results (p=0.0, but thermocycling did not (p=0.6974. Considering the SBS results (MPa, Gh-TC and Gc showed the highest values (27.59±6.4 and 27.18±2.9 and Gt-TC showed the lowest (8.45±6.7. For the Ra parameter, ANOVA revealed that the aging method had an effect (p=0.0157 but the surface treatments did not (p=0.458. For the thermocycled and non-thermocycled groups, Ra (µm was 0.69±0.16 and 1.12±0.52, respectively. The most frequent failure mode exhibited was mixed failure involving the enamel-resin-bracket interfaces. CONCLUSION: Regardless of the aging method, Gh promoted similar SBS results to Gc, suggesting that rebonded ceramic brackets are a more effective strategy.

  13. Two-zone modeling of diesel / biodiesel blended fuel operated ceramic coated direct injection diesel engine

    Directory of Open Access Journals (Sweden)

    B. Rajendra Prasath, P. Tamil Porai, Mohd. F. Shabir

    2010-11-01

    Full Text Available A comprehensive computer code using ”C” language was developed for compression ignition (C.I engine cycle and modified in to low heat rejection (LHR engine through wall heat transfer model. Combustion characteristics such as cylinder pressure, heat release, heat transfer and performance characteristics such as work done, specific fuel consumption (SFC and brake thermal efficiency (BTE were analysed. On the basis of first law of thermodynamics the properties at each degree crank angle was calculated. Preparation and reaction rate model was used to calculate the instantaneous heat release rate. The effect of coating on engine heat transfer was analysed using a gas-wall heat transfer calculations and total heat transfer was based on ANNAND’s combined heat transfer model. The predicted results are validated through the experiments on the test engine under identical operating conditions on a turbocharged D.I diesel engine. In this analysis 20% of biodiesel (derived from Jatropha seed oil blended with diesel was used in both conventional and LHR engine. The simulated combustion and performance characteristics are found satisfactory with the experimental results.

  14. CO2 laser cladding heterogeneous ceramic-metal wear-resistant coatings

    Science.gov (United States)

    Fomin, V. M.; Malikov, A. G.; Orishich, A. M.

    2016-10-01

    The microstructure, hardness property and wear resistance of WC, Ni-Cr and Fe powders deposited by laser cladding at varying processing parameters were investigated. The results of the present study revealed the prospects of multilayer cladding of R6M5 high-speed tool steel (analog of M2 steel (USA) and HS6-5-2 steel (EU)) onto low-alloy steel with the use of a laser beam. Controlling thermal cycles of laser cladding, it is possible to obtain a clad coating made of high-speed steel having the structure of high-alloy austenite-martensite mixture with disperse inclusions of carbides up to 10 mm thick, i.e., it is actually possible to create bimetal structures. The wear resistance of the laser-clad self-fluxing PG-10N-01 (Ni-Cr-B-Si-C) alloy increases by a factor of 5 due to addi-tional hardening by cast tungsten carbide (WC) with spherical particles. As a result, it becomes higher than the wear resistance of high-speed steel by more than a factor of 3.

  15. Electrochemical promotion of propane oxidation on Pt deposited on a dense β″-Al2O3 ceramic Ag+ conductor

    Science.gov (United States)

    Tsampas, Mihalis N.; Kambolis, Anastasios; Obeid, Emil; Lizarraga, Leonardo; Sapountzi, Foteini M.; Vernoux, Philippe

    2013-01-01

    A new kind of electrochemical catalyst based on a Pt porous catalyst film deposited on a β″-Al2O3 ceramic Ag+ conductor was developed and evaluated during propane oxidation. It was observed that, upon anodic polarization, the rate of propane combustion was significantly electropromoted up to 400%. Moreover, for the first time, exponential increase of the catalytic rate was evidenced during galvanostatic transient experiment in excellent agreement with EPOC equation. PMID:24790942

  16. Electrochemical promotion of propane oxidation on Pt deposited on a dense β″-Al2O3 ceramic Ag(+) conductor.

    Science.gov (United States)

    Tsampas, Mihalis N; Kambolis, Anastasios; Obeid, Emil; Lizarraga, Leonardo; Sapountzi, Foteini M; Vernoux, Philippe

    2013-01-01

    A new kind of electrochemical catalyst based on a Pt porous catalyst film deposited on a β″-Al2O3 ceramic Ag(+) conductor was developed and evaluated during propane oxidation. It was observed that, upon anodic polarization, the rate of propane combustion was significantly electropromoted up to 400%. Moreover, for the first time, exponential increase of the catalytic rate was evidenced during galvanostatic transient experiment in excellent agreement with EPOC equation.

  17. Shape-dependent plasma-catalytic activity of ZnO nanomaterials coated on porous ceramic membrane for oxidation of butane.

    Science.gov (United States)

    Sanjeeva Gandhi, M; Mok, Young Sun

    2014-12-01

    In order to explore the effects of the shape of ZnO nanomaterials on the plasma-catalytic decomposition of butane and the distribution of byproducts, three types of ZnO nanomaterials (nanoparticles (NPs), nanorods (NRs) and nanowires (NWs)) were prepared and coated on multi-channel porous alumina ceramic membrane. The structures and morphologies of the nanomaterials were confirmed by X-ray diffraction method and scanning electron microscopy. The observed catalytic activity of ZnO in the oxidative decomposition of butane was strongly shape-dependent. It was found that the ZnO NWs exhibited higher catalytic activity than the other nanomaterials and could completely oxidize butane into carbon oxides (COx). When using the bare or ZnO NPs-coated ceramic membrane, several unwanted partial oxidation and decomposition products like acetaldehyde, acetylene, methane and propane were identified during the decomposition of butane. When the ZnO NWs- or ZnO NRs-coated membrane was used, however, the formation of such unwanted byproducts except methane was completely avoided, and full conversion into COx was achieved. Better carbon balance and COx selectivity were obtained with the ZnO NWs and NRs than with the NPs. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. A Theoretical Model for Predicting Residual Stress Generation in Fabrication Process of Double-Ceramic-Layer Thermal Barrier Coating System.

    Science.gov (United States)

    Song, Yan; Wu, Weijie; Xie, Feng; Liu, Yilun; Wang, Tiejun

    2017-01-01

    Residual stress arisen in fabrication process of Double-Ceramic-Layer Thermal Barrier Coating System (DCL-TBCs) has a significant effect on its quality and reliability. In this work, based on the practical fabrication process of DCL-TBCs and the force and moment equilibrium, a theoretical model was proposed at first to predict residual stress generation in its fabrication process, in which the temperature dependent material properties of DCL-TBCs were incorporated. Then, a Finite Element method (FEM) has been carried out to verify our theoretical model. Afterwards, some important geometric parameters for DCL-TBCs, such as the thickness ratio of stabilized Zirconia (YSZ, ZrO2-8%Y2O3) layer to Lanthanum Zirconate (LZ, La2Zr2O7) layer, which is adjustable in a wide range in the fabrication process, have a remarkable effect on its performance, therefore, the effect of this thickness ratio on residual stress generation in the fabrication process of DCL-TBCs has been systematically studied. In addition, some thermal spray treatment, such as the pre-heating treatment, its effect on residual stress generation has also been studied in this work. It is found that, the final residual stress mainly comes from the cooling down process in the fabrication of DCL-TBCs. Increasing the pre-heating temperature can obviously decrease the magnitude of residual stresses in LZ layer, YSZ layer and substrate. With the increase of the thickness ratio of YSZ layer to LZ layer, magnitudes of residual stresses arisen in LZ layer and YSZ layer will increase while residual stress in substrate will decrease.

  19. A Theoretical Model for Predicting Residual Stress Generation in Fabrication Process of Double-Ceramic-Layer Thermal Barrier Coating System

    Science.gov (United States)

    Song, Yan; Wu, Weijie; Xie, Feng; Liu, Yilun; Wang, Tiejun

    2017-01-01

    Residual stress arisen in fabrication process of Double-Ceramic-Layer Thermal Barrier Coating System (DCL-TBCs) has a significant effect on its quality and reliability. In this work, based on the practical fabrication process of DCL-TBCs and the force and moment equilibrium, a theoretical model was proposed at first to predict residual stress generation in its fabrication process, in which the temperature dependent material properties of DCL-TBCs were incorporated. Then, a Finite Element method (FEM) has been carried out to verify our theoretical model. Afterwards, some important geometric parameters for DCL-TBCs, such as the thickness ratio of stabilized Zirconia (YSZ, ZrO2-8%Y2O3) layer to Lanthanum Zirconate (LZ, La2Zr2O7) layer, which is adjustable in a wide range in the fabrication process, have a remarkable effect on its performance, therefore, the effect of this thickness ratio on residual stress generation in the fabrication process of DCL-TBCs has been systematically studied. In addition, some thermal spray treatment, such as the pre-heating treatment, its effect on residual stress generation has also been studied in this work. It is found that, the final residual stress mainly comes from the cooling down process in the fabrication of DCL-TBCs. Increasing the pre-heating temperature can obviously decrease the magnitude of residual stresses in LZ layer, YSZ layer and substrate. With the increase of the thickness ratio of YSZ layer to LZ layer, magnitudes of residual stresses arisen in LZ layer and YSZ layer will increase while residual stress in substrate will decrease. PMID:28103275

  20. Effect of sandblasting, silica coating, and laser treatment on the microtensile bond strength of a dental zirconia ceramic to resin cements.

    Science.gov (United States)

    Mahmoodi, Nasrin; Hooshmand, Tabassom; Heidari, Solmaz; Khoshro, Kimia

    2016-02-01

    The purpose of this in vitro study was to evaluate the effect of laser irradiation as well as other surface treatment methods on the microtensile bond strength of a dental zirconia ceramic to the two types of resin cements. Zirconia ceramic blocks (ICE Zirkon) were sintered according to the manufacturer's instructions and duplicated in resin composites. The ceramic specimens were divided into four groups according to the following surface treatments: no surface treatment (control), sandblasting with alumina, silica coating plus silanization, and Nd:YAG laser irradiation. The specimens were divided equally and then bonded with Panavia F2.0 (self-etching resin cement) and Clearfil SA Luting (self-adhesive resin cement) to the composite blocks. The bonded ceramic-composite blocks were stored in distilled water at 37 °C for 72 h, cut to prepare bar-shaped specimens with a bonding area of approximately 1 mm(2), and thermocycled for 3000 cycles between 5 and 55 °C, and the microtensile bond strengths were measured using a universal testing machine. The data were analyzed by ANOVA and Tukey post hoc test. The results showed that the self-adhesive resin cement used in this study did not improve the microtensile bond strength when the zirconia surface was sandblasted by alumina. The use of the Nd:YAG laser did not enhance the bond strength between the zirconia and both types of resin cements. In addition, silica coating of the zirconia surfaces plus silane application significantly improved the bond strength regardless of the type of resin cement utilized.

  1. The APS ceramic chambers

    Energy Technology Data Exchange (ETDEWEB)

    Milton, S.; Warner, D.

    1994-07-01

    Ceramics chambers are used in the Advanced Photon Source (APS) machines at the locations of the pulsed kicker and bumper magnets. The ceramic will be coated internally with a resistive paste. The resistance is chosen to allow the low frequency pulsed magnet field to penetrate but not the high frequency components of the circulating beam. Another design goal was to keep the power density experienced by the resistive coating to a minimum. These ceramics, their associated hardware, the coating process, and our recent experiences with them are described.

  2. IPcote9183金属陶瓷涂层制备及其性能%Performance of Metallic-Ceramic Anti-Corrosion Coating IPcote9183

    Institute of Scientific and Technical Information of China (English)

    王维

    2011-01-01

    An aluminium containing high-temperature anti-corrosion water-based paint was used to prepare metallic-ceramic coating, and performance of the coating was studied. The results showed that the coating was uniform and had good adhesion under the conditions of a certain spray pressure and nozzle/sample distance. The coating thickness was 0. 01 - 0. 02 mm for every IPcote9183 layer. The thickness could increase by repeating spray + dry. The coating with thickness of 0. 02 ~ 0. 03 mm was used to salt fog test and there was no red rust after 1000 h.%用一种进口水基含铝高温防腐蚀涂料制备了金属陶瓷涂层,介绍了制备的工艺,对该涂层的性能进行了研究.结果表明,按照一定的喷涂压力和喷涂距离进行喷涂,可获得表面均匀、结合良好的涂层.喷涂一层IPcote9183可以获得厚度为0.01 mm~0.02 mm的涂层;可进行多层喷涂.厚度为0.02~0.03mm的涂层,中性盐雾试验可达到1000 h不出现红锈.

  3. Surfaces, Coatings and Protection

    Science.gov (United States)

    Ferguson, I. F.

    1982-08-01

    Plasma sprayed ceramics, sputter ion plating, and sol-gel ceramic protective coatings for nuclear reactors are discussed. The influence of such coatings on the behavior of reactor fuel elements is noted. The investigation of such coatings by diffraction methods is described. Laser and nuclear microprobes, scanning transmission electron microscopes, neutron scattering, and image analysis are summarized.

  4. Creep, Fatigue and Fracture Behavior of Environmental Barrier Coating and SiC-SiC Ceramic Matrix Composite Systems: The Role of Environment Effects

    Science.gov (United States)

    Zhu, Dongming; Ghosn, Louis J.

    2015-01-01

    Advanced environmental barrier coating (EBC) systems for low emission SiCSiC CMC combustors and turbine airfoils have been developed to meet next generation engine emission and performance goals. This presentation will highlight the developments of NASAs current EBC system technologies for SiC-SiC ceramic matrix composite combustors and turbine airfoils, their performance evaluation and modeling progress towards improving the engine SiCSiC component temperature capability and long-term durability. Our emphasis has also been placed on the fundamental aspects of the EBC-CMC creep and fatigue behaviors, and their interactions with turbine engine oxidizing and moisture environments. The EBC-CMC environmental degradation and failure modes, under various simulated engine testing environments, in particular involving high heat flux, high pressure, high velocity combustion conditions, will be discussed aiming at quantifying the protective coating functions, performance and durability, and in conjunction with damage mechanics and fracture mechanics approaches.

  5. Comparative study of formation and corrosion performance of porous alumina and ceramic nanorods formed in different electrolytes by anodization

    Energy Technology Data Exchange (ETDEWEB)

    Raj, V., E-mail: alaguraj2@rediffmail.com; Mumjitha, M., E-mail: mumjitha@gmail.com

    2014-01-15

    Highlights: • Alumina–titania coatings were fabricated by anodization in a single step. • The universal and cheap sulphuric acid was used as the reference electrolyte. • The minimum concentration of PTO is used to achieve ceramic nanorods. • Dense ceramic coatings were achieved at low current density and room temperature. • Anodized coatings show better corrosion resistance compared to bare aluminium. -- Abstract: Fabrication of Al{sub 2}O{sub 3}–TiO{sub 2} nanoceramic coatings on aluminium was carried out in a single step using cost effective sulphuric acid electrolyte with the addition of potassium titanium oxalate (PTO) by anodization method. For comparison, the anodization was also carried out in sulphuric acid electrolyte alone. The effect of composition of the electrolyte, current density and electrolyte concentration on formation and surface characteristics of anodic alumina and ceramic coatings produced from different electrolytes have been investigated. The growth process, surface morphology, nanostructure, distribution of chemical elements, phase constitutions and corrosion resistance of the coatings formed in two different electrolytes were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Tafel polarization technique and electrochemical impedance spectroscopy (EIS). As the concentration of electrolyte and current density increased, the surface properties of the coating increased up to certain content and beyond that they decreased. Dense, uniform nanoceramic coatings with less surface defects were obtained from sulphuric acid + PTO electrolyte. The corrosion studies reveal that ceramic coating formed in sulphuric acid + PTO electrolyte offers better corrosion resistance compared to the alumina coating formed in sulphuric acid electrolyte.

  6. Dip-coating and Co-sintering of Ceramic Interconnect for Tubular SOFC%管式SOFC陶瓷连接体的浸渍法制备与共烧

    Institute of Scientific and Technical Information of China (English)

    魏涛; 周新萍; 钟巍; 高庆宇; 吕小丽; 王绍荣

    2014-01-01

    A cost-effective method was developed to fabricate dense La0.8Sr0.2Cr0.5Fe0.5O3-δ(LSCrF) interconnect membrane on NiO-YSZ anode substrate for tubular solid oxide fuel cell (SOFC) applications by one-step dip-coating, and co-sintering of the ceramic interconnect with the anode. The LSCrF powder was synthesized with citric acid assisted sol-gel method, the phase structure was characterized by an XRD, and the particle size distribution of the ball-milled powder was analyzed by a Mastersizer 2000 analyzer. It can be concluded that with the powder calcined at 700℃and ball-milled for 12 h, LSCrF iflm can be successfully prepared on the anode support of NiO-YSZ by a dip-coating process. After being co-sintered at 1400℃, a dense LSCrF interconnect membrane can be obtained.%讨论了采用一步浸渍法在管式固体氧化物燃料电池(SOFC)的NiO-YSZ阳极上制作致密La0.8Sr0.2Cr0.5Fe0.5O3-δ(LSCrF)陶瓷连接体薄膜的可行性;实现了阳极素坯与连接体的共烧,可简化燃料电池的制作过程并降低成本。采用柠檬酸盐法合成LSCrF粉体,利用XRD对合成粉体的物相进行分析,采用马尔文Mastersizer 2000-激光粒度仪对球磨后粉体的粒度分布进行测试。实验结果表明,经700℃煅烧的粉体,再经过12 h球磨之后,可以成功地用浸渍法沉积到NiO-YSZ支撑阳极,在1400℃下共烧结而得到致密的连接体薄膜。

  7. The effect of MAO processing time on surface properties and low temperature infrared emissivity of ceramic coating on aluminium 6061 alloy

    Science.gov (United States)

    Al Bosta, Mohannad M. S.; Ma, Keng-Jeng; Chien, Hsi-Hsin

    2013-09-01

    MAO ceramic coatings were prepared on aluminium 6061 surfaces at different treating durations (10, 20, ... 60 min), using alkali silicate electrolyte and pulsed bipolar current mode. The surface microstructures and properties were studied using SEM, XRD, EDX and a surface roughness tester. Image-Pro Plus and MATCH! softwares were used to analyze SEM micrographs and XRD results, respectively. The infrared emissivities of the ceramic coatings were measured at the 70 °C using FTIR spectrometer. We found a linear correlation between the volcano-like area and the surface roughness. The compositions and phases were associated with the volcano-like population and area. The curve of IR spectral emissivity was influenced by surface roughness, γ-alumina, sillimanite and cristobalite phases. The emissivity was enhanced by the surface roughness in the ranges 4.0-9.6 μm and 10.5-14.8 μm. In the range 7.0-8.0 μm, α-alumina and sillimanite phases enhanced the emissivity, while the cristobalite has a negative impact to the emissivity. A negative contributions were found for α-alumina in the region 9.6-16.0 μm and for the surface thickness in the region 15.0-16.0 μm. Overall, the average of long wave infrared (LWIR) emissivity ranged from 87.05% to 91.65%.

  8. Laser assembly nanostructured Al2O3/TiO2 coating on cast aluminum surface

    Institute of Scientific and Technical Information of China (English)

    ZHANG Guang-jun; DAI Jian-qiang; WANG Hui-ping; YAN Min-jie; XI Wen-long; ZOU Chang-gu; GE Da-fang

    2004-01-01

    CO2 laser quick assembly technology is adopted on the surface of cast aluminum ZL104 to form a dense ceramic coating containing a great deal of nanometer Al2O3/TiO2 particles which eliminate cracks and porosities.The major phases of the coating are α-Al2O3 andβ-TiO2. The micro-hardness distribution of the coating is 1 813,1 504, 1 485 and 1 232 (HV0.05). The bonding strength of the coating LC1 is 11.4 N, which is 7.26 times higher than that of the conventional hot-spraying Al2O3/TiO2 coating. It has been proved by analysis that the bonding strength is achieved because of the effects of both super-quick laser consolidation and the nanometer effect of nanometer ceramic material.

  9. Characterization of photocatalytically active coatings based on TiO2/Zn-Al layered double hydroxide on ceramic tiles

    OpenAIRE

    Vulić Tatjana J.; Rudić Ognjen Lj.; Ranogajec Jonjaua G.

    2013-01-01

    The self-cleaning function (photocatalytic activity and surface hydrophilicity/hydrophobicity) is of great importance for ceramic tiles from both economic and environmental point of view. This research is focused on the preparation of suitable photocatalytic suspensions studying the influence of the photocatalyst powder amount and the molecular mass of polyethylene glycol (PEG) on the self-cleaning properties of the suspensions deposited on the ceramic tile...

  10. Metal-ceramic composite coatings obtained by new thermal spray technologies: Cold Gas Spray (CGS) and its wear resistance; Recubrimientos de materiales compuestos metal-ceramico obtenidos por nuevas tecnologias de proyeccion termica: Proyeccion fria (CGS) y su resistencia al desgaste

    Energy Technology Data Exchange (ETDEWEB)

    Miguel, J. M.; Vizcaino, S.; Dosta, S.; Cinca, N.; Lorenzana, C.; Guilemany, J. M.

    2011-07-01

    In this paper, composite coatings composed by an aluminum bronze metal matrix and a hard ceramic alumina phase obtained by cold spray technique were obtained in order to increase the tribological properties of the pure bronze coatings. The different processes that occur during the coating formation (hardening of the metal particles, fragmentation of the ceramic particles, shot peening on the metal substrate, etc) are described and their effects on the coating properties are studied. Wear tests consisting on Ball-on-Disk tests, abrasion Rubber Wheel tests and erosion tests as well as microhardness and adhesion tests are carried out and the results are correlated with the ceramic phase content of the coatings. It can be concluded that the hard ceramic phase increases the tribological properties with relation of the initial bronze coating. Finally, main wear mechanisms during the tribological tests are described. (Author) 21 refs.

  11. Microstructural and mechanical evaluation of laser-assisted cold sprayed bio-ceramic coatings: potential use for biomedical applications

    CSIR Research Space (South Africa)

    Tlotleng, Monnamme

    2014-02-01

    Full Text Available .%, HAP coating and the HAP intensities were lower for this coating except for the (004) peak. The hardness values taken at the interface inferred that the 80 wt.%, HAP coating was least bonded. It was possible to conclude that when this phase material...

  12. Silicon-on-ceramic coating process. Silicon sheet growth development for the Large-Area Silicon Sheet and Cell Development Tasks of the Low-Cost Silicon Solar Array Project. Quarterly report No. 8, December 28, 1977--March 28, 1977

    Energy Technology Data Exchange (ETDEWEB)

    Chapman, P.W. Zook, J.D.; Heaps, J D; Maclolek, R B; Koepke, B; Butter, C D; Schult, S B

    1978-04-20

    A research program to investigate the technical and economic feasibility of producing solar-cell-quality sheet silicon by coating inexpensive ceramic substrates with a thin layer of polycrystalline silicon is described. The coating methods to be developed are directed toward a minimum-cost process for producing solar cells with a terrestrial conversion efficiency of 12 percent or greater. By applying a graphite coating to one face of a ceramic substrate, molten silicon can be caused to wet only that graphite-coated face and produce uniform thin layers of large-grain polycrystalline silicon; thus, only a minimal quantity of silicon is consumed. A dip-coating method for putting silicon on ceramic (SOC) has been shown to produce solar-cell-quality sheet silicon. This method and a continuous coating process also being investigated have excellent scale-up potential which offers an outstanding cost-effective way to manufacture large-area solar cells. A variety of ceramic materials have been dip-coated with silicon. The investigation has shown that mullite substrates containing an excess of SiO/sub 2/ best match the thermal expansion coefficient of silicon and hence produce the best SOC layers. With such substrates, smooth and uniform silicon layers 25 cm/sup 2/ in area have been achieved with single-crystal grains as large as 4 mm in width and several cm in length. Solar cells with areas from 1 to 10 cm/sup 2/ have been fabricated from material withas-grown surface. Recently, an antireflection (AR) coating has been applied to SOC cells. Conversion efficiencies greater than 9% have been achieved without optimizing series resistance characteristics. Such cells typically have open-circuit voltages and short-circuit current densities of 0.51 V and 20 mA/cm/sup 2/, respectively.

  13. Multifunctional Ceramic Nanostructured Coatings

    Science.gov (United States)

    2010-12-01

    manual and semiautomatic modes. In case of manual operation the sampling from database is done in compliance with inquiry filters. The restrictions on...availability of card lines selected with prescribed accuracy. In the semiautomatic mode the restrictions related to the position of revealed lines can be...cantilever substrate made from stainless steel ( grade X18H10T, Es = 220 GPa) while the film thickness gradually increased up to tf = 600 nm with its

  14. Dense Breasts

    Science.gov (United States)

    ... also appear white on mammography, they can be hidden by or within dense breast tissue. Other imaging ... understanding of the possible charges you will incur. Web page review process: This Web page is reviewed ...

  15. Adhesive and Protective Characteristics of Ceramic Coating A-417 and Its Effect on Engine Life of Forged Refractaloy-26 (AMS 5760) and Cast Stellite 21 (AMS 5385) Turbine Blades

    Science.gov (United States)

    Garrett, Floyd B; Gyorgak, Charles A

    1953-01-01

    The adhesive and protective characteristics of National Bureau of Standards Coating A-417 were investigated, as well as the effect of the coating on the life of forged Refractaloy 26 and cast Stellite 21 turbine blades. Coated and uncoated blades were run in a full-scale J33-9 engine and were subjected to simulated service operations consisting of consecutive 20-minute cycles (15 min at rated speed and approximately 5 min at idle). The ceramic coating adhered well to Refractaloy 26 and Stellite 21 turbine blades operated at 1500 degrees F. The coating also prevented corrosion of the Refractaloy 26, a corrosion-sensitive nickel-base alloy, and of the Stellite 21, a relatively corrosion-resistant cobalt-base alloy. Although the coating prevented corrosion of both alloys, it had no apparent effect on blade life.

  16. Thermal barrier coating for alloy systems

    Science.gov (United States)

    Seals, Roland D.; White, Rickey L.; Dinwiddie, Ralph B.

    2000-01-01

    An alloy substrate is protected by a thermal barrier coating formed from a layer of metallic bond coat and a top coat formed from generally hollow ceramic particles dispersed in a matrix bonded to the bond coat.

  17. PIXE (particle induced X-ray emission): A non-destructive analysis method adapted to the thin decorative coatings of antique ceramics

    Science.gov (United States)

    Leon, Y.; Sciau, Ph.; Bouquillon, A.; Pichon, L.; de Parseval, Ph.

    2012-11-01

    Recent trends in study of Greek and Roman potteries have been to develop non-abrasive methods to determine the elemental composition of their thin coatings. This paper investigates the potential of PIXE (particle induced X-ray emission) in this field. This technique has been currently used to determine the bulk elemental composition of several types of artifacts because of its fast and simultaneous ability to measure a large number of elements with good accuracy and without any damage to the sample. However, until now it has never been applied to the measurement of the composition of thin layers owing to the difficulty in limiting the depth of analysis to the layer thickness. In this paper, we show, through a comparative study of reference clay pellets and thin coatings of Terra Sigillata ceramics that reducing the energy of the particle beam the problem can be solved. The decrease of proton energy from 3 MeV (standard condition) to 1.5 MeV allowed us to limit the analyzed depth to the coating thickness without significant alteration of the results. Quantitative elemental analysis remains possible and the quality of results is similar to the one obtained from electron microprobe.

  18. PIXE (particle induced X-ray emission): A non-destructive analysis method adapted to the thin decorative coatings of antique ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Leon, Y. [CNRS, CEMES, BP 94347, 29 rue J. Marvig, F-31055 Toulouse (France); Universite de Toulouse, UPS, INSA, CEMES, F-31055 Toulouse (France); Sciau, Ph., E-mail: philippe.sciau@cemes.fr [CNRS, CEMES, BP 94347, 29 rue J. Marvig, F-31055 Toulouse (France); Universite de Toulouse, UPS, INSA, CEMES, F-31055 Toulouse (France); Bouquillon, A.; Pichon, L. [C2RMF, 14 quai F. Mitterrand, F-75001 Paris Cedex 01 (France); Parseval, Ph. de [Universite de Toulouse, CNRS, IRD, GET, 14 av. E. Belin, F-31400 Toulouse (France)

    2012-11-15

    Recent trends in study of Greek and Roman potteries have been to develop non-abrasive methods to determine the elemental composition of their thin coatings. This paper investigates the potential of PIXE (particle induced X-ray emission) in this field. This technique has been currently used to determine the bulk elemental composition of several types of artifacts because of its fast and simultaneous ability to measure a large number of elements with good accuracy and without any damage to the sample. However, until now it has never been applied to the measurement of the composition of thin layers owing to the difficulty in limiting the depth of analysis to the layer thickness. In this paper, we show, through a comparative study of reference clay pellets and thin coatings of Terra Sigillata ceramics that reducing the energy of the particle beam the problem can be solved. The decrease of proton energy from 3 MeV (standard condition) to 1.5 MeV allowed us to limit the analyzed depth to the coating thickness without significant alteration of the results. Quantitative elemental analysis remains possible and the quality of results is similar to the one obtained from electron microprobe.

  19. Chemical treatment and biomimetic coating evaluating in zirconia-alumina ceramics; Avaliacao de tratamentos quimicos e recobrimento biomimetico em ceramicas de alumina-zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Aguiar, Amanda Abati

    2007-07-01

    Ceramic materials, as alumina and zirconia have been explored along the years as biomaterials application. The bio inert nature has been stimulating the development of new alternatives, as chemical treatments to improve the biological application of these ceramics. The biomimetic process of bio inert ceramics for coating apatite is based on soaking the implant in a simulated body fluid, SBF, with ion concentrations nearly equal to those of human blood plasma. The bioactivity of the material is related with the formation of a layer constituted of hydroxyapatite low crystalline, similar to the biological apatite. The biocompatibility associated to the structural properties of the alumina and zirconia has been stimulating the clinical use of these materials, mainly in areas of larger mechanical requests, places not recommended for bioactive hydroxyapatite, for instance. In this work samples of alumina, zirconia doped with Yttria (3% mol) and composites of alumina and zirconia doped with Yttria (3% mol) were prepared by co-precipitation method, calcinate, sintered, chemically treated with solutions of acid phosphoric and sodium hydroxide and them immersed in 1.0 M and 1.5 M SBF. The calcinate powders were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), gas adsorption (BET) and laser diffraction. The XRD results indicate that the samples are low crystalline. It was observed for BET that the samples present high specific surface area. The results of laser diffraction and SEM showed that the powders are agglomerates. The sintered samples were analyzed by XRD, SEM and X-ray fluorescence (XRF). The phases quantified by Rietveld method were: cubic, tetragonal and monoclinic of the zirconia, besides the phase alpha of the alumina. The chemical treatment with phosphoric acid didn't present a tendency of larger apatite formation in relation to the samples no chemically treated. The treatment with sodium hydroxide provoked accentuated transformation

  20. Transient and residual stresses in a pressable glass-ceramic before and after resin-cement coating determined using profilometry.

    LENUS (Irish Health Repository)

    2011-05-01

    The effect of heat-pressing and subsequent pre-cementation (acid-etching) and resin-cementation operative techniques on the development of transient and residual stresses in different thicknesses of a lithium disilicate glass-ceramic were characterised using profilometry prior to biaxial flexure strength (BFS) determination.

  1. Ceramic Seal.

    Energy Technology Data Exchange (ETDEWEB)

    Smartt, Heidi A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Romero, Juan A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Custer, Joyce Olsen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hymel, Ross W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Krementz, Dan [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Gobin, Derek [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Harpring, Larry [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Martinez-Rodriguez, Michael [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Varble, Don [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); DiMaio, Jeff [Tetramer Technologies, Pendleton, SC (United States); Hudson, Stephen [Tetramer Technologies, Pendleton, SC (United States)

    2016-11-01

    Containment/Surveillance (C/S) measures are critical to any verification regime in order to maintain Continuity of Knowledge (CoK). The Ceramic Seal project is research into the next generation technologies to advance C/S, in particular improving security and efficiency. The Ceramic Seal is a small form factor loop seal with improved tamper-indication including a frangible seal body, tamper planes, external coatings, and electronic monitoring of the seal body integrity. It improves efficiency through a self-securing wire and in-situ verification with a handheld reader. Sandia National Laboratories (SNL) and Savannah River National Laboratory (SRNL), under sponsorship from the U.S. National Nuclear Security Administration (NNSA) Office of Defense Nuclear Nonproliferation Research and Development (DNN R&D), have previously designed and have now fabricated and tested Ceramic Seals. Tests have occurred at both SNL and SRNL, with different types of tests occurring at each facility. This interim report will describe the Ceramic Seal prototype, the design and development of a handheld standalone reader and an interface to a data acquisition system, fabrication of the seals, and results of initial testing.

  2. Characterization of micro-arc ceramic coatings on Ti-2Al-2.5Zr alloy substrates

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Titanium oxide coatings were synthesized on Ti-2Al-2.5Zr alloy substrates by micro-arc oxidation (MAO) technique. The surface features of the coatings were studied by scanning electron microscopy. The micro-arc discharge channels of the Ti-2Al-2.5Zr alloy decrease while the discharge channel size increases clearly with an increase in treating time. With an increase of the coating thickness the porous layer thickness increases apparently. Phase composition of the surface layers of the coatings was evaluated by X-ray diffraction and X-ray photoelectron spectroscopy. The results of XRD and XPS analysis show that the MAO coating mainly consists of anatase and rutile TiO2.

  3. Preparation and characterization of ceramic/carbon coated Fe₃O₄ magnetic nanoparticle nanocomposite as a solid-phase microextraction adsorbent.

    Science.gov (United States)

    Heidari, Hassan; Razmi, Habib; Jouyban, Abolghasem

    2012-07-06

    A novel solid-phase microextraction (SPME) fiber based on a glass tube coated with ceramic/carbon coated Fe₃O₄ magnetic nanoparticle nanocomposite (C-Fe₃O₄/C MNP) was prepared by sol-gel technique. The carbon coated Fe₃O₄ magnetic nanoparticles were synthesized by a simple hydrothermal reaction and the resultant powder was mixed with sol-gel precursors to prepare C-Fe₃O₄/C MNP. The prepared C-Fe₃O₄/C MNP was deposited on surface of glass tubes as new substrate with a simple method. The results revealed that this procedure was a simple and reproducible technique for the preparation of SPME fibers coated with magnetic nanoparticles. The scanning electron micrographs of the fiber surface revealed a three-dimensional structure which is suitable as SPME adsorbents. Some polycyclic aromatic hydrocarbons (PAHs) were selected as model compounds for evaluating performance of the designed SPME fiber. The analytes were extracted with SPME, and desorbed using acetonitrile via ultrasonication. The extracts were analyzed by high performance liquid chromatography (HPLC) with fluorescence detection. The results demonstrated that the proposed method based on the C-Fe₃O₄/C MNP fiber had wide dynamic linear range (0.01-350 μg L⁻¹) with good linearity (R²>0.990) and low detection limits (0.7-50 pg mL⁻¹). The relative standard deviation ranged from 6.9% to 12.2% for inter-day variations. These fibers were successfully used for the analysis of spiked water samples, which demonstrating the applicability of the home-made C-Fe₃O₄/C MNP fibers.

  4. Recent advances in the field of ceramic fibers and ceramic matrix composites

    Science.gov (United States)

    Naslain, R.

    2005-03-01

    Progress achieved during the last decade in the field of ceramic fibers and related ceramic matrix composites is reviewed. Both SiC-based and alumina-based fine fibers have been improved in terms of thermal stability and creep resistance with temperature limit of about 1400 and 1200 ° C, respectively. Two concepts for achieving damage-tolerant ceramic matrix composites have been identified : (i) that of non-oxide composites with a dense matrix in which matrix cracks formed under load are deflected and arrested in a weak fiber coating referred to as the interphase and (ii) that of all-oxide composites with a highly porous matrix with no need of any fiber coating. The lifetime under load of non-oxide composites in oxidizing atmospheres, is improved through the use of multilayered self-healing interphases and matrices deposited from gaseous precursors by chemical vapor infiltration (CVI). Lifetime ranging from 1000 to 10,000 hours at 1200 ° C under cyclic loading in air are foreseen. Alumina-based composites although attractive for long term exposures in oxidizing atmospheres up to ≈1200 ° C, are still experimental materials.

  5. ZrO2包覆CaO-MgO-SiO2陶瓷纤维的制备及其性能%Preparation and properties of ZrO2 coated CaO-MgO-SiO2 ceramic fiber

    Institute of Scientific and Technical Information of China (English)

    刘浩; 王玺堂; 王周福; 张保国

    2012-01-01

    为了解决CaO-MgO-SiO2陶瓷纤维在使用过程中析晶、粉化的问题,采用非均相成核法在CaO-MgO-SiO2陶瓷纤维表面制备了ZrO2涂层.用场发射扫描电子显微镜观察ZrO2包覆层,用X射线衍射仪分析800和1 000℃热处理后原始纤维和ZrO2包覆纤维的晶相变化,并检测了二者在模拟肺液中的溶解性能.结果表明:包覆处理后,CaO-MgO-SiO2陶瓷纤维表面形成了一层ZrO2包覆层;ZrO2包覆层的存在可以显著抑制800℃时纤维的析晶,1000℃时只能抑制纤维中方石英的析出,对其他物相的析晶没有明显抑制作用;ZrO2包覆层的存在降低了纤维在模拟肺液中的早期溶解速率,但对纤维的长期生物可溶性影响不大.%In order to inhibit the crystallization and pulverization of CaO-MgO-SiO2 ceramic fiber at high temperatures,the ZrO2 coating on CaO-MgO-SiOj ceramic fiber was formed by heterogeneous-nucleation method. The crystal phase compositions of the original fiber and ZrO2 coated fiber fired at 800 °C and 1 000 °C were analyzed by X-ray diffractometer.and their solubility in Gamble solution was determined. The results show that; (1) a dense ZrO2 coating is formed on the surface of fiber; (2) the coating on fiber can inhibit the precipitation of crystals at 800 °C markedly and at 1 000 °C it only can inhibit the precipitation of cristobalite and has little effects on other crystal phases; (3) the coating decreases the initial dissolution rate of the fiber in Gamble solution and has little effect on long-term bio-solubility of fiber.

  6. Interface mechanics and histomorphometric analysis of hydroxyapatite-coated and porous glass-ceramic implants in canine bone

    DEFF Research Database (Denmark)

    Nimb, L; Jensen, J S; Gotfredsen, K

    1995-01-01

    A canine study was performed to make a histological and biomechanical evaluation of the interface between bone and two different bioceramic implants. A newly developed glass-ceramic formed by P2O5, CaO, SiO2, and Al2O3, giving a crystal phase composed of CaP2O6-AlPO4-SiP2O7, was compared to hydro......A canine study was performed to make a histological and biomechanical evaluation of the interface between bone and two different bioceramic implants. A newly developed glass-ceramic formed by P2O5, CaO, SiO2, and Al2O3, giving a crystal phase composed of CaP2O6-AlPO4-SiP2O7, was compared...

  7. Quantitative Analysis of Life Index of Electrothermal-Film Coated Ceramic Heating Elements with Rare-Earth Element Doped

    Institute of Scientific and Technical Information of China (English)

    He Ping

    2004-01-01

    For electrothermal-film heating elements for ceramics, the quantitative expression of the relation between the contents of multicomponent semiconductor dope and rare-earth element additive through the multivariate statistical regression analysis was presented, and the optimum control index of the multicomponent semiconductor dope and the rareearth element for the maximum life was also determined. The research shows that the life value ranging from 15 to 20 thousand hours can be ensured only if the evaluation grade of metal oxide dope in the compounding formula is controlled between grades 0.5 to 1.2. The relation of the content of multicomponent rare-earth element dope and the life index of electrothermal-film heating material for ceramics was determined theoretically.

  8. Two Phase Monazite/Xenotime 30LaPO4-70YPO4 Coating of Ceramic Fiber Tows (Postprint)

    Science.gov (United States)

    2008-04-01

    Strength and Thermal Stability,’’ J. Am. Ceram. Soc. 89 [11], 3475–80 (2006). 8D. J. Srolovitz and S. A. Safran , ‘‘Capillary Instabilities in Thin Films...I. En- ergetics,’’ J. Appl. Phys., 60, 247–54 (1986). 9D. J. Srolovitz and S. A. Safran , ‘‘Capillary Instabilities in Thin Films. II. Ki- netics,’’ J

  9. Recent Progress in the Development of Neodymium Doped Ceramic Yttria

    Science.gov (United States)

    Prasad, Narasimha S.; Edwards, Chris; Trivedi, Sudhir B.; Kutcher, Susan; Wang, Chen-Chia; Kim, Joo-Soo; Hommerich, Uwe; Shukla, Vijay; Sadangi, Rajendra; Kear, Bernard

    2007-01-01

    Solid-state lasers play a significant role in providing the technology necessary for active remote sensing of the atmosphere. Neodymium doped yttria (Nd:Y2O3) is considered to be an attractive material due to its possible lasing wavelengths of aprrox.914 nm and approx.946 nm for ozone profiling. These wavelengths when frequency tripled can generate UV light at approx.305 nm and approx.315 nm, which is particularly useful for ozone sensing using differential absorption lidar technique. For practical realization of space based UV transmitter technology, ceramic Nd:Y2O3 material is considered to possess great potential. A plasma melting and quenching method has been developed to produce Nd3+ doped powders for consolidation into Nd:Y2O3 ceramic laser materials. This far-from-equilibrium processing methodology allows higher levels of rare earth doping than can be achieved by equilibrium methods. The method comprises of two main steps: (a) plasma melting and quenching to generate dense, and homogeneous doped metastable powders, (b) pressure assisted consolidation of these powders by hot isostatic pressing to make dense nanocomposite ceramics. Using this process, several 1" x 1" ceramic cylinders have been produced. The infrared transmission of undoped Y2O3 ceramics was as high as approx.75% without anti-reflection coating. In the case of Nd:Y2O3 ceramics infrared transmission values of approx.50% were achieved. Furthermore, Nd:Y2O3 samples with dopant concentrations of up to approx.2 at. % were prepared without significant emission quenching.

  10. Electrochemical and in vitro bioactivity of polypyrrole/ceramic nanocomposite coatings on 316L SS bio-implants

    Energy Technology Data Exchange (ETDEWEB)

    Madhan Kumar, A. [Center of Research Excellence in Corrosion, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Nagarajan, S. [Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, Tokyo (Japan); Ramakrishna, Suresh [Graduate School of Biomedical Science and Engineering/College of Medicine, Hanyang University, Sungdong-gu, Seoul (Korea, Republic of); Sudhagar, P.; Kang, Yong Soo [Energy Materials Laboratory, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, Hyongbum [Graduate School of Biomedical Science and Engineering/College of Medicine, Hanyang University, Sungdong-gu, Seoul (Korea, Republic of); Gasem, Zuhair M. [Center of Research Excellence in Corrosion, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Rajendran, N., E-mail: nrajendran@annauniv.edu [Department of Chemistry, Anna University, Chennai (India)

    2014-10-01

    The present investigation describes the versatile fabrication and characterization of a novel composite coating that consists of polypyrrole (PPy) and Nb{sub 2}O{sub 5} nanoparticles. Integration of the two materials is achieved by electrochemical deposition on 316L stainless steel (SS) from an aqueous solution of oxalic acid containing pyrrole and Nb{sub 2}O{sub 5} nanoparticles. Fourier transform infrared spectral (FTIR) and X-ray diffraction (XRD) studies revealed that the existence of Nb{sub 2}O{sub 5} nanoparticles in PPy matrix with hexagonal structure. Surface morphological analysis showed that the presence of Nb{sub 2}O{sub 5} nanoparticles strongly influenced the surface nature of the nanocomposite coated 316L SS. Micro hardness results revealed the enhanced mechanical properties of PPy nanocomposite coated 316L SS due to the addition of Nb{sub 2}O{sub 5} nanoparticles. The electrochemical studies were carried out using cyclic polarization and electrochemical impedance spectroscopy (EIS) measurements. In order to evaluate the biocompatibility, contact angle measurements and in vitro characterization were performed in simulated body fluid (SBF) and on MG63 osteoblast cells. The results showed that the nanocomposite coatings exhibit superior biocompatibility and enhanced corrosion protection performance over 316L SS than pure PPy coatings. - Highlights: • Effect of Nb{sub 2}O{sub 5} nanoparticles on the bio activity of PPy coatings was evaluated. • Hydrophilic, more compact and smooth morphology of nanocomposite was achieved. • Nb{sub 2}O{sub 5} nanoparticles enhanced the corrosion protection performance of PPy coating. • Mechanical and surface wettability of nanocomposite exhibited higher than PPy. • Nano Nb{sub 2}O{sub 5} in PPy coating improved the biocompatibility on osteoblast MG63 cells.

  11. Fabrication of mullite-bonded porous SiC ceramics from multilayer-coated SiC particles through sol-gel and in-situ polymerization techniques

    Science.gov (United States)

    Ebrahimpour, Omid

    In this work, mullite-bonded porous silicon carbide (SiC) ceramics were prepared via a reaction bonding technique with the assistance of a sol-gel technique or in-situ polymerization as well as a combination of these techniques. In a typical procedure, SiC particles were first coated by alumina using calcined powder and alumina sol via a sol-gel technique followed by drying and passing through a screen. Subsequently, they were coated with the desired amount of polyethylene via an in-situ polymerization technique in a slurry phase reactor using a Ziegler-Natta catalyst. Afterward, the coated powders were dried again and passed through a screen before being pressed into a rectangular mold to make a green body. During the heating process, the polyethylene was burnt out to form pores at a temperature of about 500°C. Increasing the temperature above 800°C led to the partial oxidation of SiC particles to silica. At higher temperatures (above 1400°C) derived silica reacted with alumina to form mullite, which bonds SiC particles together. The porous SiC specimens were characterized with various techniques. The first part of the project was devoted to investigating the oxidation of SiC particles using a Thermogravimetric analysis (TGA) apparatus. The effects of particle size (micro and nano) and oxidation temperature (910°C--1010°C) as well as the initial mass of SiC particles in TGA on the oxidation behaviour of SiC powders were evaluated. To illustrate the oxidation rate of SiC in the packed bed state, a new kinetic model, which takes into account all of the diffusion steps (bulk, inter and intra particle diffusion) and surface oxidation rate, was proposed. Furthermore, the oxidation of SiC particles was analyzed by the X-ray Diffraction (XRD) technique. The effect of different alumina sources (calcined Al2O 3, alumina sol or a combination of the two) on the mechanical, physical, and crystalline structure of mullite-bonded porous SiC ceramics was studied in the

  12. Surface coating of graphite pebbles for Korean HCCR TBM

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Youngmin [National Fusion Research Institute, Daejeon (Korea, Republic of); Yun, Young-Hoon, E-mail: yunh2@dsu.ac.kr [Dongshin University, Naju (Korea, Republic of); Park, Yi-Hyun; Ahn, Mu-Young; Cho, Seungyon [National Fusion Research Institute, Daejeon (Korea, Republic of)

    2014-10-15

    Highlights: • A CVR-SiC coating was successfully formed on graphite pebbles for neutron reflector. • Dense and fine-grained surface morphologies of the SiC coatings were observed. • Oxidation resistance of the CVR-SiC-coated graphite pebbles was improved. - Abstract: The new concept of the recently modified Helium-Cooled Ceramic Reflector (HCCR) Test Blanket Module (TBM) is to adopt a graphite reflector in the form of a pebble bed. A protective SiC coating is applied to the graphite pebbles to prohibit their reaction with steam or air as well as dust generation during TBM operation. In this research, the chemical vapor reaction (CVR) method was applied to fabricate SiC-coated graphite pebbles in a silica source. Relatively dense CVR-SiC coating was successfully formed on the graphite pebbles through the reduction of the graphite phase with SiO gas that was simply created from the silica source at 1850 °C (2 h). The microstructural features, XRD patterns, pore-size distribution and oxidation behavior of the SiC-coated graphite pebbles were investigated. To develop the practical process, which will be applied for mass production hereafter, a novel alternative method was applied to form the layer of SiC coating on the graphite pebbles over the silica source.

  13. Wear Performance of Sequentially Cross-Linked Polyethylene Inserts against Ion-Treated CoCr, TiNbN-Coated CoCr and Al2O3 Ceramic Femoral Heads for Total Hip Replacement

    Directory of Open Access Journals (Sweden)

    Christian Fabry

    2015-02-01

    Full Text Available The aim of the present study was to evaluate the biotribology of current surface modifications on femoral heads in terms of wettability, polyethylene wear and ion-release behavior. Three 36 mm diameter ion-treated CoCr heads and three 36 mm diameter TiNbN-coated CoCr heads were articulated against sequentially cross-linked polyethylene inserts (X3 in a hip joint simulator, according to ISO 14242. Within the scope of the study, the cobalt ion release in the lubricant, as well as contact angles at the bearing surfaces, were investigated and compared to 36 mm alumina ceramic femoral heads over a period of 5 million cycles. The mean volumetric wear rates were 2.15 ± 0.18 mm3·million cycles−1 in articulation against the ion-treated CoCr head, 2.66 ± 0.40 mm3·million cycles−1 for the coupling with the TiNbN-coated heads and 2.17 ± 0.40 mm3·million cycles−1 for the ceramic heads. The TiNbN-coated femoral heads showed a better wettability and a lower ion level in comparison to the ion-treated CoCr heads. Consequently, the low volumes of wear debris, which is comparable to ceramics, and the low concentration of metal ions in the lubrication justifies the use of coated femoral heads.

  14. 高强度低密度树脂覆膜陶粒研究%Study on High Strength and Low Density Resin Coated Ceramic Proppants

    Institute of Scientific and Technical Information of China (English)

    张伟民; 李宗田; 李庆松; 陈文将; 蒙传幼; 崔彦立

    2013-01-01

    A method of manufacturing high strength and low density resin coated ceramic proppants was developed,and the effects of dosage of phenolic resin and coupling agent,et al,on the sphericity,roundness,acid solubility,turbidity,density,crush resistance and short term flow conductivity of the procured resin coated ceramic were also discussed.The results showed that the apparent density and bulk density of the resin coated ceramic particles (RCCP) decreased by 8.1% and 11.2%,respectively,compared to that of the resin coated quartz sand(RCQZ) ; and the crushing rate of the RCCP and RCQZ under 69 MPa was 1.7% and 8.1%,respectively.The roundness of the RCCP was better than that of the RCQZ; as a result,the short term flow conductivity of the RCCP could be improved more than one time compared to that of the RCQZ.Based on conductivity data,the mechanism that the oil flow conductivity of the RCCP was bigger than the water flow conductivity was proposed.The field test of the RCCP was conducted in 5 wells of Wenmi oil field.It was proved by field construction that the average yield of crude oil per well was increased by 1.35 t and the water cut per well decreased by 7.9%.%本文报道了一种低密度高强度树脂覆膜陶粒支撑剂的制备方法,讨论了酚醛树脂含量和偶联剂含量等及对覆膜低密度陶粒圆球度、密度、酸溶解度、破碎率及导流能力的影响,并采用覆膜低密度陶粒进行了现场试验.结果表明:树脂覆膜低密度陶粒比覆膜石英砂的视密度和体积密度分别降低8.1%和11.2%,69 MPa下二者的破碎率分别为1.7%和8.1%,树脂覆膜低密度陶粒的圆球度更好,短期导流能力能提高一倍以上.依据实验结果提出了树脂覆膜支撑剂对油导流能力高于对水导流能力的机理.采用树脂覆膜低密度陶粒在温米油田进行现场试验5井次,平均单井增油13.5 t/d,含水下降7.9%.

  15. Development and Performance Evaluations of HfO2-Si and Rare Earth-Si Based Environmental Barrier Bond Coat Systems for SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming

    2014-01-01

    Ceramic environmental barrier coatings (EBC) and SiCSiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft propulsion systems because of their ability to significantly increase engine operating temperatures, improve component durability, reduce engine weight and cooling requirements. Advanced EBC systems for SiCSiC CMC turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant material development challenges for the high temperature CMC components is to develop prime-reliant, high strength and high temperature capable environmental barrier coating bond coat systems, since the current silicon bond coat cannot meet the advanced EBC-CMC temperature and stability requirements. In this paper, advanced NASA HfO2-Si based EBC bond coat systems for SiCSiC CMC combustor and turbine airfoil applications are investigated. The coating design approach and stability requirements are specifically emphasized, with the development and implementation focusing on Plasma Sprayed (PS) and Electron Beam-Physic Vapor Deposited (EB-PVD) coating systems and the composition optimizations. High temperature properties of the HfO2-Si based bond coat systems, including the strength, fracture toughness, creep resistance, and oxidation resistance were evaluated in the temperature range of 1200 to 1500 C. Thermal gradient heat flux low cycle fatigue and furnace cyclic oxidation durability tests were also performed at temperatures up to 1500 C. The coating strength improvements, degradation and failure modes of the environmental barrier coating bond coat systems on SiCSiC CMCs tested in simulated stress-environment interactions are briefly discussed and supported by modeling. The performance enhancements of the HfO2-Si bond coat systems with rare earth element dopants and rare earth-silicon based bond coats are also highlighted. The advanced bond coat systems, when

  16. Proactive control of the metal-ceramic interface behavior of thermal barrier coatings using an artificial alpha-Al2O 3 layer

    Science.gov (United States)

    Su, Yi-Feng

    The reliability and life of thermal barrier coatings (TBCs) used in the hottest sections of advanced aircraft engines and power generation systems are largely dictated by: (1) the ability of a metallic bond coating to form an adherent thermally grown oxide (TGO) at the metal-ceramic interface and (2) the rate at which the TGO grows upon oxidation. It is postulated that a thin alpha-Al2O3 layer, if it could be directly deposited on a Ni-based alloy, will guide the alloy surface to form a TGO that is more tenacious and slower growing than what is attainable with state-of-the-art bond coatings. A chemical vapor deposition (CVD) process was used to directly deposit an alpha-Al2O3 layer on the surface of a single crystal Ni-bases superalloy. The layer was 150 nm thick, and consisted of small columnar grains (˜100 to 200 nm) with alpha-Al2O 3 as the major phase with a minute amount of theta-Al2O 3. Within 0.5 h of oxidation at 1150°C, the resulting TGO formed on the alloy surface underwent significant lateral grain growth. Consequently, within this time scale, the columnar nature of the TGO became well established. After 50 h, a network of ridges was clearly observed on the TGO surface instead of equiaxed grains typically observed on uncoated alloy surface. Comparison of the TGO morphologies observed with and without the CVD-Al2O 3 layer suggested that the transient oxidation of the alloy surface was considerably reduced. The alloy coated with the CVD-Al2O 3 layer also produced a much more adherent and slow growing TGO in comparison to that formed on the uncoated alloy surface. The CVD-Al2O 3 layer also improved its spallation resistance. Without the CVD-Al 2O3 layer, more than 50% of the TGO spalled off the alloy surface after 500 h in oxidation with significant wrinkling of the TGO that remained on the alloy surface. In contrast, the TGO remained intact with the CVD-Al2O3 layer after the 500 h exposure. Furthermore, the CVD layer significantly reduced the degree of

  17. Hot Corrosion Behavior of Double-ceramic-layer LaTi2Al9O19/YSZ Thermal Barrier Coatings

    Institute of Scientific and Technical Information of China (English)

    XIE Xiaoyun; GUO Hongbo; GONG Shengkai; XU Huibin

    2012-01-01

    LaTi2Al9O19 (LTA) exhibits promising potential as a new kind of thermal barrier coating (TBC) material,due to its excellent high-temperature capability and low thermal conductivity.In this paper,LTA/yttria stabilized zirconia (YSZ) TBCs are produccd by atmospheric plasma spraying.Hot corrosion behavior and the related failure mechanism of the coating are investigated.Decomposition of LTA does not occur even after 1 458 hot corrosion cycles at 1 373 K,revealing good chemical stability in molten salt of Na2SO4 and NaCl.However,the molten salt infiltrates to the bond coat,causing dissolving of the thermally grown oxide (TGO) in the molten salt and hot corrosion of the bond coat.As a result,cracking of the TBC occurs within the oxide layer.In conclusion,the ceranic materials LTA and YSZ reveal good chemical stability in molten salts of Na2SO4 and NaCl,and the bond coat plays a significant role in providing protection for the component against hot corrosion in the LTA/YSZ TBCs.LTA exhibits very promising potential as a novel TBC material.

  18. Electrochemical and in vitro bioactivity of polypyrrole/ceramic nanocomposite coatings on 316L SS bio-implants.

    Science.gov (United States)

    Madhan Kumar, A; Nagarajan, S; Ramakrishna, Suresh; Sudhagar, P; Kang, Yong Soo; Kim, Hyongbum; Gasem, Zuhair M; Rajendran, N

    2014-10-01

    The present investigation describes the versatile fabrication and characterization of a novel composite coating that consists of polypyrrole (PPy) and Nb2O5 nanoparticles. Integration of the two materials is achieved by electrochemical deposition on 316L stainless steel (SS) from an aqueous solution of oxalic acid containing pyrrole and Nb2O5 nanoparticles. Fourier transform infrared spectral (FTIR) and X-ray diffraction (XRD) studies revealed that the existence of Nb2O5 nanoparticles in PPy matrix with hexagonal structure. Surface morphological analysis showed that the presence of Nb2O5 nanoparticles strongly influenced the surface nature of the nanocomposite coated 316L SS. Micro hardness results revealed the enhanced mechanical properties of PPy nanocomposite coated 316L SS due to the addition of Nb2O5 nanoparticles. The electrochemical studies were carried out using cyclic polarization and electrochemical impedance spectroscopy (EIS) measurements. In order to evaluate the biocompatibility, contact angle measurements and in vitro characterization were performed in simulated body fluid (SBF) and on MG63 osteoblast cells. The results showed that the nanocomposite coatings exhibit superior biocompatibility and enhanced corrosion protection performance over 316L SS than pure PPy coatings.

  19. Modification of the composite multi-layer oxide ceramic coating on meteoroid shielding element by compression plasma flow

    Science.gov (United States)

    Astashinski, V. M.; Khramtsov, P. P.; Hryshchanka, U. M.; Chernik, M. Yu; Vasetskij, V. A.; Shikh, I. A.; Doroshko, M. V.; Makhnach, A. I.

    2016-11-01

    The aim of this work is investigation of the influence of high-energy plasma impact on composite multi-layer coating (NiAl as a sublayer and Al2O3 as a top coat) on meteoroid shielding element. In order to reach this goal qausi-stationary plasma accelerator with impulse gas feeding was used. Experiments were conducted with use of helium and hydrogen gas mixture and nitrogen as plasma forming substance. Plasma accelerator generates plasma jet with electron temperature ≈ 150 kK and electron density (2.5-4) × 1016 cm-3. Visual examination, photography and spectral measurements were made through special vacuum chamber optical windows.

  20. HIGHWAY INFRASTRUCTURE FOCUS AREA NEXT-GENERATION INFRASTRUCTURE MATERIALS VOLUME I - TECHNICAL PROPOSAL & MANAGEMENTENHANCEMENT OF TRANSPORTATION INFRASTRUCTURE WITH IRON-BASED AMORPHOUS-METAL AND CERAMIC COATINGS

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J C

    2007-12-04

    . The high boron content of this particular amorphous metal made it an effective neutron absorber, and suitable for criticality control applications. These amorphous alloys appear to maintain their corrosion resistance up to the glass transition temperature. Visionary research is proposed to extend the application of corrosion-resistant iron-based amorphous metal coatings, and variants of these coatings, to protection of the Nation's transportation infrastructure. Specific objectives of the proposed work are: (1) fabrication of appropriate test samples for evaluation of concept; (2) collection of production and test data for coated steel reinforcement bars, enabling systematic comparison of various coating options, based upon performance and economic considerations; and (3) construction and testing of concrete structures with coated steel reinforcement bars, thereby demonstrating the value of amorphous-metal coatings. The benefits of ceramic coatings as thermal barriers will also be addressed.

  1. Effect of Anodic Current Density on Characteristics and Low Temperature IR Emissivity of Ceramic Coating on Aluminium 6061 Alloy Prepared by Microarc Oxidation

    Directory of Open Access Journals (Sweden)

    Mohannad M. S. Al Bosta

    2013-01-01

    Full Text Available High emitter MAO ceramic coatings were fabricated on the Al 6061 alloy, using different bipolar anodic current densities, in an alkali silicate electrolyte. We found that, as the current density increased from 10.94 A/dm2 to 43.75 A/dm2, the layer thickness was increased from 10.9 μm to 18.5 μm, the surface roughness was increased from 0.79 μm to 1.27 μm, the area ratio of volcano-like microstructure was increased from 55.6% to 59.6%, the volcano-like density was decreased from 2620 mm−2 to 1420 mm−2, and the γ-alumina phase was decreased from 66.6 wt.% to 26.2 wt.%, while the α-alumina phase was increased from 3.9 wt.% to 27.6 wt.%. The sillimanite and cristobalite phases were around 20 wt.% and 9 wt.%, respectively, for 10.94 A/dm2 and approximately constant around 40 wt.% and less than 5 wt.%, respectively, for the anodic current densities 14.58, 21.88, and 43.75 A/dm2. The ceramic surface roughness and thickness slightly enhanced the IR emissivity in the semitransparent region (4.0–7.8 μm, while the existing phases contributed together to raise the emissivity in the opaque region (8.6–16.0 μm to higher but approximately the same emissivities.

  2. Experimental study of the drying in dense fluidized beds of a synthetic mud coated with support particulates; Etude experimentale du sechage en lit fluidise dense d'une boue synthetique enrobee sur des particules supports

    Energy Technology Data Exchange (ETDEWEB)

    Gode, C.; Shakourzadeh, K. [Universite de Technologie de Compiegne, L.G.P.I., 60 (France)

    2001-07-01

    This article presents the results of an experimental study of a new drying process for muddy materials and based on the fluidization technique. The granular phase has been obtained by the coating with mud of a porous mineral support, inert and recyclable in the process. Activated porous particulates of alumina (2-5 mm) have been chosen because of their heat transfer properties. A first part of the experimental study concerns the drying process. The second part concerns the attrition and elutriation mechanisms. The experimental measurements have been performed with a laboratory fluidized column (internal diameter = 150 mm) and with a fluidized column (internal diameter = 400 mm) from a semi-industrial facility. The air velocity and the drying temperature are the main adjustment parameters. The working temperatures have been fixed between 20 and 150 deg. C. (J.S.)

  3. Preparation of Nickle-adulterated Foam Ceramics and Nickle-coated on its Surface%Al2O3泡沫金属复合陶瓷的制备及表面包镍处理

    Institute of Scientific and Technical Information of China (English)

    杨少锋; 晏彬彬; 吴阳; 李恺

    2013-01-01

    采用有机泡沫前驱体浸渍工艺制备Al2O3泡沫金属复合陶瓷.通过涂覆处理获得缺陷较少、结构均匀的泡沫金属复合陶瓷;采用Ni(NO3)2·6H2O液相包覆+氢气热还原技术对泡沫金属复合陶瓷体表面进行金属化处理.采用SEM、EDS研究了含镍泡沫陶瓷体的结构及金属化处理后的表面形貌.结果表明,镍颗粒均匀地分布在泡沫陶瓷骨架内部,骨架中心宏观孔保持通孔;经包覆处理后,金属层较均匀地附着于陶瓷表面.%The open cell Nickle-adulterated alumina foam ceramics were prepared by impregnating a polymeric sponge with aqueous ceramic slurry. The Nickle-adulterated alumina foam ceramics with a very u-niform macrostructure and few flaws were produced by recoating process. A nickelousnitrate liquid-phase coating and deoxidized by hydrogen method was used to deposit Ni on the surface of Ni-adulterated alumina foams. Coating morphology and microstructure of the foam ceramics were observed by SEM (scanning electron microscope) and EDS (energy dispersed spectrometer). The results indicate that Ni particles are distributed uniformly in the foam skeleton and pores in the sintered body exhibit interconnected. Furthermore, Ni is successfully coated on alumina foams surface after coating process.

  4. Fabrication, Properties and Applications of Dense Hydroxyapatite: A Review

    Directory of Open Access Journals (Sweden)

    Mythili Prakasam

    2015-12-01

    Full Text Available In the last five decades, there have been vast advances in the field of biomaterials, including ceramics, glasses, glass-ceramics and metal alloys. Dense and porous ceramics have been widely used for various biomedical applications. Current applications of bioceramics include bone grafts, spinal fusion, bone repairs, bone fillers, maxillofacial reconstruction, etc. Amongst the various calcium phosphate compositions, hydroxyapatite, which has a composition similar to human bone, has attracted wide interest. Much emphasis is given to tissue engineering, both in porous and dense ceramic forms. The current review focusses on the various applications of dense hydroxyapatite and other dense biomaterials on the aspects of transparency and the mechanical and electrical behavior. Prospective future applications, established along the aforesaid applications of hydroxyapatite, appear to be promising regarding bone bonding, advanced medical treatment methods, improvement of the mechanical strength of artificial bone grafts and better in vitro/in vivo methodologies to afford more particular outcomes.

  5. 磁力磨削Al2 O3-TiO2陶瓷涂层试验%Experimental Research on Magnetic Abrasive Finishing Ceramic Coating with Al2 O3-TiO2

    Institute of Scientific and Technical Information of China (English)

    焦龙飞; 高国富

    2016-01-01

    采用磁力研磨技术进行Al2 O3-TiO2陶瓷涂层的精密加工,设计了平面陶瓷研磨的试验装置,通过研究磨粒粒度等参数对表面粗糙度的影响规律,得出精密加工的最优参数。%The precision machining technology of ceramic coating with coating ceramic are discussed.The experimen-tal setup of magnetic abrasive finishing (MAF)was developed to study the mechanism and characteristics of finishing ce-ramic coating with Al2 O3-TiO2 .A magnetic field of the experimental device is provided by permanent magnet.The influence of machining parameters on the finished surface roughness was discussed and the optimal parameter of the precision machi-ning was obtained.

  6. Investigation on plasma-sprayed ZrO2 thermal barrier coating on nickel alloy substrate

    Institute of Scientific and Technical Information of China (English)

    卢安贤; 常鹰; 蔡小梅

    2002-01-01

    The thermal barrier coatings with NiCrAlY alloy bonding layer, NiCrAlY-Y2O3 stabilized ZrO2 transition layer and Y2O3 stabilized ZrO2 ceramic layer are prepared on nickel alloy substrates using the plasma spray technique. The relationship among the composition, structure and property of the coatings are investiga-ted by means of optical microscope, scanning electronic microscope and the experiments of thermal shock resistance cycling and high temperature oxidation resistance. The results show that the structure design of introdu-cing a transition layer between Ni alloy substrate and ZrO2 ceramic coating guarantees the high quality and properties of the coatings; ZrO2 coatings doped with a little SiO2 possesses better thermal shock resistance and more excellent hot corrosion resistance as compared with ZrO2 coating materials without SiO2 ;the improvement in performance of ZrO2 coating doped with SiO2 is due to forming more dense coating structure by self- closing effects of the flaws and pores in the ZrO2 coatings.

  7. 纳米银羟基磷灰石涂层正畸陶瓷托槽的抗菌与力学性能%Antibacterial and mechanical properties of ceramic orthodontic brackets with nano silver hydroxyapatite coating

    Institute of Scientific and Technical Information of China (English)

    周冠军; 杨大鹏; 刘新芳; 胡博

    2015-01-01

    背景:临床口腔正畸过程中,陶瓷托槽存在抗菌性能和力学性能不足的情况,容易导致各种不良事件的出现,影响正畸效果。目的:观察纳米银羟基磷灰石涂层陶瓷托槽的抗菌与力学性能。方法:制备纳米银羟基磷灰石涂层陶瓷托槽,采用扫描电镜观察涂层表面,并进行涂层表面定量抗菌实验。将50颗离体人上颌前磨牙随机分为2组,实验组(n=25)粘接纳米银羟基磷灰石涂层陶瓷托槽,对照组(n=25)粘接普通陶瓷托槽,检测两组抗剪切强度。结果与结论:纳米银羟基磷灰石涂层整体结构有序,均匀致密,羟基磷灰石具有多孔状结构,孔径属于微纳米级别,其中均匀分布大量纳米银颗粒。定量抗菌实验显示,纳米银羟基磷灰石涂层陶瓷托槽对大肠杆菌、白色葡萄球菌有较强的抑制作用,抗菌率均在95%以上。实验组抗剪切强度低于对照组(P <0.05)。表明纳米银羟基磷灰石涂层陶瓷托槽具有良好的抗菌和力学性能,满足临床正畸过程中力学变化的需求。%BACKGROUND:In the clinical orthodontics, ceramic brackets have deficiencies in the aspects of antibacterial and mechanical properties, which easily lead to the emergence of a variety of adverse events and influence the orthodontic effect. OBJECTIVE:To observe the antibacterial and mechanical properties of nano silver hydroxyapatite coating ceramic brackets. METHODS:The nano silver hydroxyapatite coating ceramic brackets were prepared. Scanning electron microscopy was used to observe the coating surface. Coating antibacterial experiment was conducted. Totaly 50 in vitro human maxilary premolars were randomly divided into two groups (n=25 per group): experimental and control groups. Premolars in the experimental group were bonded to nano silver coating hydroxyapatite ceramic brackets, and premolars in the control group were bonded to ordinary ceramic brackets. The

  8. Photocatalysis-assisted water filtration: using TiO2-coated vertically aligned multi-walled carbon nanotube array for removal of Escherichia coli O157:H7.

    Science.gov (United States)

    Oza, Goldie; Pandey, Sunil; Gupta, Arvind; Shinde, Sachin; Mewada, Ashmi; Jagadale, Pravin; Sharon, Maheshwar; Sharon, Madhuri

    2013-10-01

    A porous ceramic was coated with vertically aligned multi-walled carbon nanotubes (MWCNTs) by spray pyrolysis. Titanium dioxide (TiO2) nanoparticles were then coated onto this densely aligned MWCNT. The presence of TiO2/MWCNT interfacial arrays was confirmed by X-ray diffraction (XRD), scanning electron microscope-energy dispersive analysis of X-ray (SEM-EDAX) and transmission electron microscope (TEM). This is a novel report in which water loaded with a most dreadful enterohemorrhagic pathogenic strain of Escherichia coli O157:H7 was filtered through TiO2/MWCNT coated porous ceramic filter and then analysed. Bacterial removal performance was found to be significantly lower in control i.e. plain porous ceramic (PTiO2/MWCNT coated ceramic. The photocatalytic killing rate constant for TiO2-ceramic and MWCNT/TiO2-ceramic under fluorescent light was found be 1.45×10(-2) min(-1) and 2.23×10(-2) min(-1) respectively. Further, when I-V characteristics were performed for TiO2/MWCNT composite, it was corroborated that the current under light irradiation is comparatively higher than that in dark, thus proving it to be photocatalytically efficient system. The enhanced photocatalysis may be a contribution of increased surface area and charge transfer rate as a consequence of aligned MWCNT network.

  9. Thermocycling effect on microshear bond strength to zirconia ceramic using Er:YAG and tribochemical silica coating as surface conditioning.

    Science.gov (United States)

    Gomes, Ana Luísa; Ramos, João Carlos; Santos-del Riego, Sérgio; Montero, Javier; Albaladejo, Alberto

    2015-02-01

    The purpose of this study is to evaluate the thermocycling effect on the microshear bond strength (μSBS) of different self-adhesive resin cements to zirconia using tribochemical silica coating Rocatec™ (ROC) and Er:YAG as surface conditioners. Two hundred forty square-like zirconia samples were polished and randomly assigned in four groups according surface treatment applied as follows: (1) no treatment (NT), (2) silica coating with ROC, 3) Er:YAG laser irradiation (LAS: 2.940 nm, 200 mJ; 10 Hz), and (4) laser followed by Rocatec™ (LAROC). Each group was divided into two subgroups according the resin tested as follows: (A) BiFix SE (BIF) and (B) Clearfil SA (CLE). After 24 h, half of the specimens from each subgroup were tested. The other half was stored and thermocycled (5-55 °C/5,000 cycles). A μSBS test was performed using a universal testing machine (cross head speed = 0.5 mm/min). Failure modes were recorded and observed by scanning electronic microscopy. Data was analyzed with ANOVA, Student's t test, and chi-square tests, and linear regression was performed (p 10-MDP when used on zirconia surface coated with silica, independently of previous Er:YAG surface treatment.

  10. Mixed ionic and electronic conducting ceramic membranes for hydrocarbon processing

    Science.gov (United States)

    Van Calcar, Pamela; Mackay, Richard; Sammells, Anthony F.

    2002-01-01

    The invention relates to mixed phase materials for the preparation of catalytic membranes which exhibit ionic and electronic conduction and which exhibit improved mechanical strength compared to single phase ionic and electronic conducting materials. The mixed phase materials are useful for forming gas impermeable membranes either as dense ceramic membranes or as dense thin films coated onto porous substrates. The membranes and materials of this invention are useful in catalytic membrane reactors in a variety of applications including synthesis gas production. One or more crystalline second phases are present in the mixed phase material at a level sufficient to enhance the mechanical strength of the mixture to provide membranes for practical application in CMRs.

  11. Y-TZP/LZAS 微晶玻璃功能梯度涂层残余应力分析%Analysis on the residual stresses in Y-TZP/LZAS glass-ceramic gradient coatings

    Institute of Scientific and Technical Information of China (English)

    龚伟; 周黎明; 王恩泽

    2014-01-01

    Y-TZP/LZAS glass-ceramic gradient coatings on Q235 steel substrate were designed in order to im-prove the toughness of glass-ceramic coatings.The effects of the number of graded layers,coating thickness and the volume difference of 3Y-TZP between layers on the residual stress were analyzed by using finite element software.The results show that radial compressive stress was distributed on the surface of graded coatings. There are clear stress concentration in the coating/substrate interface edge.The layer numbers,the coating thickness,and the volume difference of 3Y-TZP between layers have an important influence on radial stress, axial stress and shear stress in the coating/substrate interface.Y-TZP/ LZAS glass-ceramic gradient coatings were fabricated on the Q235 steel substrate via slurry methord.The residual stress of gradient coatings were measured by X-ray diffraction approach to verify the reliability of the simulation.%为了提高钢基体微晶玻璃涂层的韧性,设计了 Y-TZP/LZAS 微晶玻璃功能梯度涂层。运用有限元软件,分析了梯度层数目、梯度层厚度和层间3Y-TZP 体积组分差等参数对涂层/基体界面残余热应力的影响。结果表明,涂层表层主要分布为径向压应力;在涂层/基体界面的边缘区域应力集中较为严重;涂层/基体界面处的径向应力、轴向应力和剪切应力以及梯度层数目、梯度层厚度和3Y-TZP 体积组分差均有密切关系。最后通过涂搪法制备了梯度涂层,测试了涂层表面残余应力,并与有限元结果对比,以验证模拟的准确性。

  12. Sol-gel derived ceramic electrolyte films on porous substrates

    Energy Technology Data Exchange (ETDEWEB)

    Kueper, Timothy Walter [Univ. of California, Berkeley, CA (United States)

    1992-05-01

    A process for the deposition of sol-gel derived thin films on porous substrates has been developed; such films should be useful for solid oxide fuel cells and related applications. Yttria-stabilized zirconia films have been formed from metal alkoxide starting solutions. Dense films have been deposited on metal substrates and ceramic substrates, both dense and porous, through dip-coating and spin-coating techniques, followed by a heat treatment in air. X-ray diffraction has been used to determine the crystalline phases formed and the extent of reactions with various substrates which may be encountered in gas/gas devices. Surface coatings have been successfully applied to porous substrates through the control of substrate pore size and deposition parameters. Wetting of the substrate pores by the coating solution is discussed, and conditions are defined for which films can be deposited over the pores without filling the interiors of the pores. Shrinkage cracking was encountered in films thicker than a critical value, which depended on the sol-gel process parameters and on the substrate characteristics. Local discontinuities were also observed in films which were thinner than a critical value which depended on the substrate pore size. A theoretical discussion of cracking mechanisms is presented for both types of cracking, and the conditions necessary for successful thin formation are defined. The applicability of these film gas/gas devices is discussed.

  13. Sol-gel derived ceramic electrolyte films on porous substrates

    Energy Technology Data Exchange (ETDEWEB)

    Kueper, T.W.

    1992-05-01

    A process for the deposition of sol-gel derived thin films on porous substrates has been developed; such films should be useful for solid oxide fuel cells and related applications. Yttria-stabilized zirconia films have been formed from metal alkoxide starting solutions. Dense films have been deposited on metal substrates and ceramic substrates, both dense and porous, through dip-coating and spin-coating techniques, followed by a heat treatment in air. X-ray diffraction has been used to determine the crystalline phases formed and the extent of reactions with various substrates which may be encountered in gas/gas devices. Surface coatings have been successfully applied to porous substrates through the control of substrate pore size and deposition parameters. Wetting of the substrate pores by the coating solution is discussed, and conditions are defined for which films can be deposited over the pores without filling the interiors of the pores. Shrinkage cracking was encountered in films thicker than a critical value, which depended on the sol-gel process parameters and on the substrate characteristics. Local discontinuities were also observed in films which were thinner than a critical value which depended on the substrate pore size. A theoretical discussion of cracking mechanisms is presented for both types of cracking, and the conditions necessary for successful thin formation are defined. The applicability of these film gas/gas devices is discussed.

  14. Application of response surface methodology on investigating flank wear in machining hardened steel using PVD TiN coated mixed ceramic insert

    Directory of Open Access Journals (Sweden)

    Ashok Kumar Sahoo

    2013-10-01

    Full Text Available The paper presents the development of flank wear model in turning hardened EN 24 steel with PVD TiN coated mixed ceramic insert under dry environment. The paper also investigates the effect of process parameter on flank wear (VBc. The experiments have been conducted using three level full factorial design techniques. The machinability model has been developed in terms of cutting speed (v, feed (f and machining time (t as input variable using response surface methodology. The adequacy of model has been checked using correlation coefficients. As the determination coefficient, R2 (98% is higher for the model developed; the better is the response model fits the actual data. In addition, residuals of the normal probability plot lie reasonably close to a straight line showing that the terms mentioned in the model are statistically significant. The predicted flank wear has been found to lie close to the experimental value. This indicates that the developed model can be effectively used to predict the flank wear in the hard turning. Abrasion and diffusion has been found to be the dominant wear mechanism in machining hardened steel from SEM micrographs at highest parametric range. Machining time has been found to be the most significant parameter on flank wear followed by cutting speed and feed as observed from main effect plot and ANOVA study.

  15. Ceramic Technology Project

    Energy Technology Data Exchange (ETDEWEB)

    1992-03-01

    The Ceramic Technology Project was developed by the USDOE Office of Transportation Systems (OTS) in Conservation and Renewable Energy. This project, part of the OTS's Materials Development Program, was developed to meet the ceramic technology requirements of the OTS's automotive technology programs. Significant accomplishments in fabricating ceramic components for the USDOE and NASA advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. These programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and data base and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially. A five-year project plan was developed with extensive input from private industry. In July 1990 the original plan was updated through the estimated completion of development in 1993. The objective is to develop the industrial technology base required for reliable ceramics for application in advanced automotive heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. Although this is a generic materials project, the focus is on the structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barrier and wear applications in these engines. To facilitate the rapid transfer of this technology to US industry, the major portion of the work is being done in the ceramic industry, with technological support from government laboratories, other industrial laboratories, and universities.

  16. Using a ceramic chamber in kicker magnets

    Energy Technology Data Exchange (ETDEWEB)

    Kurennoy, S.

    1993-05-01

    A ceramic chamber inside kicker magnets can provide the relevant field risetime. On the other hand, some metallic coating inside has to prevent static charge buildup and shield the beam from ceramic and ferrite at high frequencies to avoid possible resonances. The issues concerning the metallized ceramic chamber, such as coupling impedances and requirements on the coating, are studied to find a compromise solution for kickers of the Medium Energy Booster at the Superconducting Super Collider.

  17. Environmental Stability and Oxidation Behavior of HfO2-Si and YbGd(O) Based Environmental Barrier Coating Systems for SiCSiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Farmer, Serene; McCue, Terry R.; Harder, Bryan; Hurst, Janet B.

    2017-01-01

    Ceramic environmental barrier coatings (EBC) and SiCSiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft propulsion systems because of their ability to significantly increase engine operating temperatures, improve component durability, reduce engine weight and cooling requirements. Advanced EBC systems for SiCSiC CMC turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant material development challenges for the high temperature CMC components is to develop prime-reliant, environmental durable environmental barrier coating systems. In this paper, the durability and performance of advanced Electron Beam-Physical Vapor Deposition (EB-PVD) NASA HfO2-Si and YbGdSi(O) EBC bond coat top coat systems for SiCSiC CMC have been summarized. The high temperature thermomechanical creep, fatigue and oxidation resistance have been investigated in the laboratory simulated high-heat-flux environmental test conditions. The advanced NASA EBC systems showed promise to achieve 1500C temperature capability, helping enable next generation turbine engines with significantly improved engine component temperature capability and durability.

  18. Portfolio: Ceramics.

    Science.gov (United States)

    Hardy, Jane; And Others

    1982-01-01

    Describes eight art activities using ceramics. Elementary students created ceramic tiles to depict ancient Egyptian and medieval European art, made ceramic cookie stamps, traced bisque plates on sketch paper, constructed clay room-tableaus, and designed clay relief masks. Secondary students pit-fired ceramic pots and designed ceramic Victorian…

  19. Portfolio: Ceramics.

    Science.gov (United States)

    Hardy, Jane; And Others

    1982-01-01

    Describes eight art activities using ceramics. Elementary students created ceramic tiles to depict ancient Egyptian and medieval European art, made ceramic cookie stamps, traced bisque plates on sketch paper, constructed clay room-tableaus, and designed clay relief masks. Secondary students pit-fired ceramic pots and designed ceramic Victorian…

  20. Application of Thermal Spray and Ceramic Coatings and Reinforced Epoxy for Cavitation Damage Repair of Hydroelectric Turbines and Pumps

    Science.gov (United States)

    1993-03-01

    forming it to the desired contour, without voids . If conditions warrant, the component may be heated to a temperature of 130 to 140 °F using electric...then applied, but the short working life and difficultly working with the epoxy caused the bowl to be underfilled . High spots were ground by hand and...the bowl was blasted to remove all of the surface glaze. Additional epoxy was used to fill void areas. 38 The second bowl was blast cleaned and coated

  1. Dense Packing

    Science.gov (United States)

    Hauck, J.; Mika, K.

    Phyllotaxis of plant organs, bacterial ordering and animal coat patterns are analyzed for homogeneity and density. The patterns are approximated by 15 tiles and characterized by the self-coordination numbers T1, T2, T3 of the nearest, next-nearest and third neighbors of the vertices of the tiles. Homogeneous structures with integer Ti values and maximum densities are obtained for distichous, whorled or spiral growth of leaves. Similar T1 values, such as T1=5 and 6 of sunflower seeds or bacteriae, give rise to maximum density. Inhomogeneous structures like the striped patterns of zebras with T1=1, 2 and 3 connections have a higher density than homogeneous stripes with T1=2. Maximum density is also obtained in icosahedral viruses.

  2. Carbon-coated ceramic membrane reactor for the production of hydrogen by aqueous-phase reforming of sorbitol.

    Science.gov (United States)

    Neira D'Angelo, M F; Ordomsky, V; Schouten, J C; van der Schaaf, J; Nijhuis, T A

    2014-07-01

    Hydrogen was produced by aqueous-phase reforming (APR) of sorbitol in a carbon-on-alumina tubular membrane reactor (4 nm pore size, 7 cm long, 3 mm internal diameter) that allows the hydrogen gas to permeate to the shell side, whereas the liquid remains in the tube side. The hydrophobic nature of the membrane serves to avoid water loss and to minimize the interaction between the ceramic support and water, thus reducing the risks of membrane degradation upon operation. The permeation of hydrogen is dominated by the diffusivity of the hydrogen in water. Thus, higher operation temperatures result in an increase of the flux of hydrogen. The differential pressure has a negative effect on the flux of hydrogen due to the presence of liquid in the larger pores. The membrane was suitable for use in APR, and yielded 2.5 times more hydrogen than a reference reactor (with no membrane). Removal of hydrogen through the membrane assists in the reaction by preventing its consumption in undesired reactions.

  3. Effect of rare earth doping on thermo-physical properties of lanthanum zirconate ceramic for thermal barrier coatings

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hongming; YI Danqing

    2008-01-01

    The effect of rare earth doping on thermo-physical properties of lanthanum zirconate was investigated. Oxide powders of various compositions La2Zr2O7 were synthesized by coprecipitation-calcination method. High-temperature dilatometer, DSC, and laser thermal dif-fusivity methods were used to analyze thermal expansion coefficient (TEC), specific heat, and thermal diffusivity. The results showed that CeO2 doped pyrochlores La2(Zr1.8Ce0.2)2O7 and La1.7(DyNd)0.15(Zr0.8Ce0.2)2O7 had higher TEC than La2Zr2O7 and Lal.7Dyo.3Zr207. La2(Zr1.8Ce0.2)2O7, La1.7Oy0.3Zr2O7, and La1.7(DyNd)0.15(Zr0.8Ce0.2)2O7 had lower thermal conductivity than undoped La2Zr2O7. The Dy203, Nd2O3, and CeO2 codoped composition showed the lowest thermal conductivity and the highest TEC. Thermo-physical results also indicated that TEC of rare earth oxide doped La2Zr2O7 ceramic was slightly higher than that of conventional ZrO2-8wt.% Y2O3 (8YSZ), and its thermal conductivity was lower than that of 8YSZ.

  4. Mechanically reliable scales and coatings

    Energy Technology Data Exchange (ETDEWEB)

    Tortorelli, P.F.; Alexander, K.B. [Oak Ridge National Lab., TN (United States)

    1995-06-01

    In many high-temperature fossil energy systems, corrosion and deleterious environmental effects arising from reactions with reactive gases and condensible products often compromise materials performance and, as a consequence, degrade operating efficiencies. Protection of materials from such reactions is best afforded by the formation of stable surface oxides (either as deposited coatings or thermally grown scales) that are slowly reacting, continuous, dense, and adherent to the substrate. However, the ability of normally brittle ceramic films and coatings to provide such protection has long been problematical, particularly for applications involving numerous or severe high-temperature thermal cycles or very aggressive (for example, sulfidizing) environments. A satisfactory understanding of how scale and coating integrity and adherence are improved by compositional, microstructural, and processing modifications is lacking. Therefore, to address this issue, the present work is intended to define the relationships between substrate characteristics (composition, microstructure, and mechanical behavior) and the structure and protective properties of deposited oxide coatings and/or thermally grown scales. Such information is crucial to the optimization of the chemical, interfacial, and mechanical properties of the protective oxides on high-temperature materials through control of processing and composition and directly supports the development of corrosion-resistant, high-temperature materials for improved energy and environmental control systems.

  5. Direct ceramic inkjet printing of yttria-stabilized zirconia electrolyte layers for anode-supported solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Tomov, R.I.; Hopkins, S.C. [Applied Superconductivity and Cryoscience Group, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB4 3QZ (United Kingdom); Krauz, M.; Kluczowski, J.R. [Institute of Power Engineering, Ceramic Department CEREL, 36-040 Boguchwala (Poland); Jewulski, J. [Institute of Power Engineering, Fuel Cells Department, 02-981 Warsaw (Poland); Glowacka, D.M. [Detector Physics Group, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE (United Kingdom); Glowacki, B.A. [Applied Superconductivity and Cryoscience Group, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB4 3QZ (United Kingdom); Institute of Power Engineering, Fuel Cells Department, 02-981 Warsaw (Poland)

    2010-11-01

    Electromagnetic drop-on-demand direct ceramic inkjet printing (EM/DCIJP) was employed to fabricate dense yttria-stabilized zirconia (YSZ) electrolyte layers on a porous NiO-YSZ anode support from ceramic suspensions. Printing parameters including pressure, nozzle opening time and droplet overlapping were studied in order to optimize the surface quality of the YSZ coating. It was found that moderate overlapping and multiple coatings produce the desired membrane quality. A single fuel cell with a NiO-YSZ/YSZ ({proportional_to}6 {mu}m)/LSM + YSZ/LSM architecture was successfully prepared. The cell was tested using humidified hydrogen as the fuel and ambient air as the oxidant. The cell provided a power density of 170 mW cm{sup -2} at 800 C. Scanning electron microscopy (SEM) revealed a highly coherent dense YSZ electrolyte layer with no open porosity. These results suggest that the EM/DCIJP inkjet printing technique can be successfully implemented to fabricate electrolyte coatings for SOFC thinner than 10 {mu}m and comparable in quality to those fabricated by more conventional ceramic processing methods. (author)

  6. Advanced Ceramics Property Measurements

    Science.gov (United States)

    Salem, Jonathan; Helfinstine, John; Quinn, George; Gonczy, Stephen

    2013-01-01

    Mechanical and physical properties of ceramic bodies can be difficult to measure correctly unless the proper techniques are used. The Advanced Ceramics Committee of ASTM, C-28, has developed dozens of consensus test standards and practices to measure various properties of a ceramic monolith, composite, or coating. The standards give the "what, how, how not, and why" for measurement of many mechanical, physical, thermal, and performance properties. Using these standards will provide accurate, reliable, and complete data for rigorous comparisons with other test results from your test lab, or another. The C-28 Committee has involved academics, producers, and users of ceramics to write and continually update more than 45 standards since the committee's inception in 1986. Included in this poster is a pictogram of the C-28 standards and information on how to obtain individual copies with full details or the complete collection of standards in one volume.

  7. Combustion chemical vapor desposited