Effect of intracrystalline water on micro-Vickers hardness in tetragonal hen egg-white lysozyme single crystals

International Nuclear Information System (INIS)

Koizumi, H; Kawamoto, H; Tachibana, M; Kojima, K

2008-01-01

Mechanical properties of high quality tetragonal hen egg-white lysozyme single crystals which are one type of protein crystal were investigated by the indentation method. The indentation marks were clearly observed on the crystal surface and no elastic recovery of them occurred. The value of the micro-Vickers hardness in the wet condition was estimated to be about 20 MPa at room temperature. The hardness greatly depended on the amount of intracrystalline water (mobile water) contained in the crystals. The hardness increased with increasing evaporation time to air at room temperature. It reached the maximum at about 260 MPa, which is 13 times as much as that in the wet condition. The origin of such a change in hardness was explained in terms of the dislocation mechanisms in lysozyme single crystals

The hardness of the hydroxyapatite-titania bilayer coatings by microindentation and nanoindentation testing

Science.gov (United States)

SIDANE, Djahida; KHIREDDINE, Hafit; YALA, Sabeha

2017-12-01

The aim of this paper is to investigate the effect of the addition of titania (TiO2) inner-layer on the morphological and mechanical properties of hydroxyapatite (HAP) bioceramic coatings deposited on 316L stainless steel (316L SS) by sol-gel method in order to improve the properties of hydroxyapatite and expand its clinical application. The addition of TiO2 as sublayer of a hydroxyapatite coating results in changes in surface morphology as well as an increase of the microhardness. The deposition of the inner-layer provides the formation of new types of hydroxyapatite coatings at the same condition of annealing. This represents an advantage for the various applications of the hydroxyapatite bioceramic in the medical field. Classical hardness measurements conducted on the coated systems under the same indentation load (10g) indicated that the microhardness of the HAP coating is improved by the addition of TiO2 inner-layer on the 316L stainless steel substrate. The hardness values obtained from both classical tests in microindentation and the continuous stiffness measurement mode in nanoindentation are slightly different. This is because nanoindentation is more sensitive to the surface roughness and the influence of defects that could be present into the material. Moreover, nanoindentation is the most useful method to separate the contribution of each layer in the bilayer coatings. In this study, the hardness is comparable with those reported previously for pure HAP ceramics (1.0-5.5 GPa) which are close to the properties of natural teeth.

Mapping residual stress fields from Vickers hardness indents using Raman microprobe spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Sparks, R.G.; Enloe, W.S.; Paesler, M.A.

1988-12-01

Micro-Raman spectroscopy is used to map the residual stress fields in the vicinity of Vickers hardness indents. Both 514.5 and 488.0 nm, light is used to excite the effect and the resulting shifted and broadened Raman peaks are analyzed using computer deconvolution. Half-wave plates are used to vary the orientation of the incident later light`s polarization state with respect to crystal orientation. The Raman scattered light is then analyzed for polarization dependences which are indicative of the various components of the Raman scattering tensor. Such studies can yield valuable information about the orientation of stress components in a well known stress field. The results can then be applied to the determination of stress components in machined semiconductor materials.

Effects of deposited nuclear and electronic energy on the hardness of R7T7-type containment glass

Energy Technology Data Exchange (ETDEWEB)

Peuget, S. [Commissariat a l' Energie Atomique, CEA Marcoule, DEN/DTCD/SECM/LMPA, Batiment 166, BP 17171, F-30207 Bagnols-sur-Ceze Cedex (France)]. E-mail: sylvain.peuget@cea.fr; Noel, P.-Y. [Commissariat a l' Energie Atomique, CEA Marcoule, DEN/DTCD/SECM/LMPA, Batiment 166, BP 17171, F-30207 Bagnols-sur-Ceze Cedex (France); Loubet, J.-L. [Laboratoire de Tribologie et Dynamique des Systemes, UMR CNRS 5513, Ecole Centrale de Lyon 36, avenue Guy de Collongue, 69134 Ecully Cedex (France); Pavan, S. [Laboratoire de Tribologie et Dynamique des Systemes, UMR CNRS 5513, Ecole Centrale de Lyon 36, avenue Guy de Collongue, 69134 Ecully Cedex (France); Nivet, P. [Commissariat a l' Energie Atomique, CEA Marcoule, DEN/DTCD/SECM/LMPA, Batiment 166, BP 17171, F-30207 Bagnols-sur-Ceze Cedex (France); Chenet, A. [Commissariat a l' Energie Atomique, CEA Marcoule, DEN/DTCD/SECM/LMPA, Batiment 166, BP 17171, F-30207 Bagnols-sur-Ceze Cedex (France)

2006-05-15

The effects of elastic and inelastic interactions induced by cumulative alpha decay on the hardness of R7T7-type nuclear containment glass were investigated on actinide-doped glass specimens and by external irradiation of inactive glass by light and heavy ions. Vickers microindentation and nanoindentation hardness measurements showed that in the deposited energy range investigated (below 3 x 10{sup 22} keV/cm{sup 3}) inelastic effects have no influence on the plastic response of the glass. Conversely, identical hardness variations versus the nuclear energy deposited in the material were observed on curium-doped glass and on glass irradiated by ion bombardment. The observed hardness variation stabilized after the deposited energy reached about 3 x 10{sup 2} keV{sub nucl}/cm{sup 3}. These findings indicate that the change in the plastic response of the glass is a consequence of ballistic effects.

Statistical analysis of the Vickers micro hardness of precipitates in a Cu-10% wt. Ni-3% wt. Al alloy using the Weibull distribution function

International Nuclear Information System (INIS)

Diaz, Gerardo; Donoso, Eduardo; Varschavsky, Ari

2004-01-01

A statistical analysis was carried out of the distribution of Vickers micro hardness values of nickel and aluminum atom precipitates from a solid solution of Cu-Ni-Al. Non isothermal calorimetric curves confirmed the formation of two types of precipitates: Ni Al from 45 K to 600 K, and Ni 3 Al from 650 K to 800 K. The micro hardness measurements were done at room temperature in the previously quenched material and submitted to isothermal and iso chronic annealing treatments. A lower dispersion in the distribution of the Vickers micro hardness values in the Ni Al precipitate for the entire formation temperature was determined with a lesser average micro hardness than the Ni 3 Al precipitate. The Weibull modules were estimated from the respective Weibull diagrams. The lesser dispersion was proven by the elevated values of the Wobble modules. The maximum average micro hardness attained by the Ni Al phase was 148, with a Weibull module of 26 and an annealing temperature of 553 K maintained for 40 minutes. The Ni 3 Al reached a maximum average micro hardness of 248 with a Weibull module of 10 and a annealing temperature of 793 K during 40 minutes (CW)

Final report on RMO Vickers key comparison COOMET M.H-K1

Science.gov (United States)

Aslanyan, E.; Menelao, F.; Herrmann, K.; Aslanyan, A.; Pivovarov, V.; Galat, E.; Dovzhenko, Y.; Zhamanbalin, M.

2013-01-01

This report describes a COOMET key comparison on Vickers hardness scales involving five National Metrology Institutes: PTB (Germany), BelGIM (Belarus), NSC IM (Ukraine), KazInMetr (Kazakhstan) and VNIIFTRI (Russia). The pilot laboratory was VNIIFTRI, and PTB acted as the linking institute to key comparisons CCM.H-K1.b and CCM.H-K1.c conducted for the Vickers hardness scales HV1 and HV30, respectively. The comparison was also conducted for the HV5 Vickers hardness scale, since this scale is most frequently used in practice in Russia and CIS countries that work according to GOST standards. In the key comparison, two sets of hardness reference blocks for the Vickers hardness scales HV1, HV5 and HV30 consisting each of three hardness reference blocks with hardness levels of 450 HV and 750 HV were used. The measurement results and uncertainty assessments for HV1 and HV30 hardness scales, as announced by BelGIM, NSC IM, KazInMetr and VNIIFTRI, are in good agreement with the key comparison reference values of CCM.H-K1.b and CCM.H-K1.c. The comparison results for the HV5 hardness scale are viewed as additional information, since up to today no CCM key comparisons on this scale have yet been carried out. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Influence of the final temperature of investment healting on the tensile strength and Vickers hardness of CP Ti and Ti-6Al-4V alloy

Directory of Open Access Journals (Sweden)

Pedro César Garcia Oliveira

2007-02-01

Full Text Available The aim of the work was to evaluate the influence of the temperature of investment healting on the tensile strength and Vickers hardness of CP Ti and Ti-6Al-4V alloy casting. Were obtained for the tensile strength test dumbbell rods that were invested in the Rematitan Plus investment and casting in the Discovery machine cast. Thirty specimens were obtained, fiftten to the CP Titanium and fifteen to the Ti-6Al-4V alloy, five samples to each an of the three temperatures of investment: 430ºC (control group, 480ºC and 530ºC. The tensile test was measured by means of a universal testing machine, MTS model 810, at a strain of 1.0 mm/min. After the tensile strenght test the specimens were secctioned, embedded and polished to hardness measurements, using a Vickers tester, Micromet 2100. The means values to tensile tests to the temperatures 430ºC, 480 and 530: CP Ti (486.1 - 501.16 - 498.14 -mean 495.30 MPa and Ti-6Al-4V alloy (961.33 - 958.26 - 1005.80 - mean 975.13 MPa while for the Vickers hardness the values were (198.06, 197.85, 202.58 - mean 199.50 and (352.95, 339.36, 344.76 - mean 345.69, respectively. The values were submitted to Analysis of Variance (ANOVA and Tukey,s Test that indicate differences significant only between the materials, but not between the temperature, for both the materias. It was conclued that increase of the temperature of investment its not chance the tensile strength and the Vickers hardness of the CP Titanium and Ti-6Al-4V alloy.

Characterization of the inhomogeneous constitutive properties of laser welding beams by the micro-Vickers hardness test and the rule of mixture

International Nuclear Information System (INIS)

Song, Yanli; Hua, Lin; Chu, Dongning; Lan, Jian

2012-01-01

Highlights: ► Relationship between Vickers hardness and material parameters was quantitatively built. ► Inhomogeneous weld properties were determined by hardness test combined the rule of mixture. ► Instrumented indentation tests verified these calculated properties of welds. ► Deviations between the calculated and experimental results were limited to 8.0%. -- Abstract: A novel approach has been proposed to characterize the inhomogeneous mechanical properties of weld materials by using the micro-Vickers hardness test combined with the rule of mixture. This proposed method has introduced the influences of the inhomogeneous properties of weld materials by considering the variations in plastic behaviour across the weld cross-section. The inhomogeneous properties of laser welding beams for tailor welded blanks (TWBs), which were three different types of combinations of DX56D and DP600 automotive steel sheets, were extracted by using this proposed method. The instrumented indentation tests were conducted to verify the measured inhomogeneous properties of weld materials. The fact that the calculated true stress–strain curves agreed well with the experimental ones has confirmed the reliability and accuracy of the proposed method.

The Compositional Variation of Microindentation Induced Densified and Plastic Deformation Volumes in Simple Silicate Glasses

DEFF Research Database (Denmark)

Hermansen, Christian; Matsuoka, Jun; Yoshida, Satoshi

2012-01-01

The densification and plastic deformation occurring in glass subjected to microindentation are established as two independent deformation mechanisms, and thought to be intimately linked to the concept of hardness and crack nucleation (quantified by the load at which radial cracks nucleate at half...

Micro-indentation fracture behavior of human enamel.

Science.gov (United States)

Padmanabhan, Sanosh Kunjalukkal; Balakrishnan, Avinash; Chu, Min-Cheol; Kim, Taik Nam; Cho, Seong Jai

2010-01-01

The purpose of this study was to determine the crack resistance behavior (K(R)) of human enamel in relation to its microstructure. Human molar teeth were precision cut, polished and tested using Vickers micro-indentation at different loads ranging from 0.98 to 9.8 N. Five indentation load levels were considered, 20 indentation cracks for each load level were introduced on the surface of the test specimen (10 indentations per tooth) and their variability was evaluated using Weibull statistics and an empirical model. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to analyze the crack morphology and propagation mechanisms involved. The results showed that enamel exhibited increasing cracking resistance (K(R)) with increasing load. It was found that the crack propagation mainly depended on the location and the microstructure it encountered. SEM showed the formation of crack bridges and crack deflection near the indentation crack tip. The crack mode was of Palmqvist type even at larger loads of 9.8 N. This was mainly attributed to the large process zone created by the interwoven lamellar rod like microstructure exhibited by the enamel surface. This study shows that there are still considerable prospects for improving dental ceramics and for mimicking the enamel structure developed by nature.

Light energy transmission and Vickers hardness ratio of bulk-fill resin based composites at different thicknesses cured by a dual-wave or a single-wave light curing unit.

Science.gov (United States)

Santini, Ario; Naaman, Reem Khalil; Aldossary, Mohammed Saeed

2017-04-01

To quantify light energy transmission through two bulk-fill resin-based composites and to measure the top to bottom surface Vickers hardness ratio (VHratio) of samples of various incremental thicknesses, using either a single-wave or dual-wave light curing unit (LCU). Tetric EvoCeram Bulk Fill (TECBF) and SonicFill (SF) were studied. Using MARC-RC, the irradiance delivered to the top surface of the samples 2, 3, 4 and 5 mm thick (n= 5 for each thickness) was adjusted to 800 mW/cm2 for 20 seconds (16 J/cm2) using either a single-wave, Bluephase or a dual-wave, Bluephase G2 LCUs. Light energy transmission through to the bottom surface of the specimens was measured at real time using MARC-RC. The Vickers hardness (VH) was determined using Vickers micro hardness tester and the VHratio was calculated. Data were analyzed using a general linear model in Minitab 16; α= 0.05. TECBF was more translucent than SF (Pwave Bluephase G2). SF showed significantly higher VH ratio than TECBF at all different thickness levels (P 0.05). TECBF showed significantly greater VH ratio when cured with the single-wave Bluephase than when using the dual-wave Bluephase G2 (Penergy through to the bottom surface and the VHratio are material dependent. Although TECBF is more translucent than SF, it showed lower VHratio compared to SF when cured with dual-wave Bluephase G2.

Thermomechanical Properties of Sb2O3-TeO2-V2O5 Glassy Systems: Thermal Stability, Glass Forming Tendency and Vickers Hardness

Science.gov (United States)

Souri, Dariush; Torkashvand, Ziba

2017-04-01

Three-component 40TeO2-(60- x)V2O5- xSb2O3 glasses with 0 ≤ x ≤ 10 (in mol.%) were obtained by the rapid melt-quenching method. These glasses were studied with respect to some mechanical properties with the goal of obtaining information about their structure. The Vickers hardness test was employed to obtain Vickers micro-hardness ( H V) at two different loads, which was within the range of 13.187-17.557 GPa for a typical 0.1 HV (0.9807 N) load. In addition, theoretical micro-hardness ( H) was investigated and compared with experimental H V, showing the elevating trend with increase of Sb2O3 content, as for H V. Furthermore, differential scanning calorimetry (DSC) was employed within the range of 150-500°C at heating rates of φ = 3 K/min, 6 K/min, 9 K/min, 10 K/min, and 13 K/min. In this work, thermal stability ( T s = T cr - T x) and glass forming tendency ( K gl) were measured and reported for these glasses to determine the relationship between the chemical composition and the thermal stability, in order to interpret the structure of glass. Generally, from the ascertained outputs [analysis of mechanical data, titration study, the values of reduced fraction of vanadium ions ( C V) and oxygen molar volume ( V_{{O}}^{*} )], it was found that the micro-hardness had an increasing trend with increasing the Sb2O3 content. Among the studied glasses, the sample with x = 8 had a higher average micro-hardness value, the highest average thermal stability and glass forming tendency with respect to the other samples, which makes it a useful material (owning very good resistance against thermal attacks) for device manufacturing.

Vickers microhardness studies on solution-grown single crystals of potassium boro-succinate

Science.gov (United States)

Lakshmipriya, M.; Rajan Babu, D.; Ezhil Vizhi, R.

2015-02-01

The semiorganic crystals of potassium boro-succinate (KBS) were grown by slow evaporation method. KBS crystallizes in monoclinic system which was confirmed by powder XRD analysis. Vickers microhardness study has been carried out over a load range of 25-100 g. The Vickers hardness numbers (Hv) of the material increases as the load increases so the material is suitable for device fabrication. The Meyer index 'n' is estimated to be greater than 1.6, the crystal system belongs to the soft material category. The elastic stiffness coefficient, c11, has also been calculated using Wooster's empirical relation from the hardness data. The fracture toughness values 'Kc', determined from measurements of crack lengths, were estimated to be 0.15166 MN/m3/2. The brittleness indices 'Bi' were estimated as 276 m-1/2.

A study of microindentation hardness tests by mechanism-based strain gradient plasticity

International Nuclear Information System (INIS)

Huang, Y.; Xue, Z.; Gao, H.; Nix, W. D.; Xia, Z. C.

2000-01-01

We recently proposed a theory of mechanism-based strain gradient (MSG) plasticity to account for the size dependence of plastic deformation at micron- and submicron-length scales. The MSG plasticity theory connects micron-scale plasticity to dislocation theories via a multiscale, hierarchical framework linking Taylor's dislocation hardening model to strain gradient plasticity. Here we show that the theory of MSG plasticity, when used to study micro-indentation, indeed reproduces the linear dependence observed in experiments, thus providing an important self-consistent check of the theory. The effects of pileup, sink-in, and the radius of indenter tip have been taken into account in the indentation model. In accomplishing this objective, we have generalized the MSG plasticity theory to include the elastic deformation in the hierarchical framework. (c) 2000 Materials Research Society

Comparative study of carp otolith hardness: lapillus and asteriscus.

Science.gov (United States)

Ren, Dongni; Meyers, Marc André; Zhou, Bo; Feng, Qingling

2013-05-01

Otoliths are calcium carbonate biominerals in the inner ear of vertebrates; they play a role in balance, movement, and sound perception. Two types of otoliths in freshwater carp are investigated using nano- and micro-indentation: asteriscus and lapillus. The hardness, modulus, and creep of asteriscus (vaterite crystals) and lapillus (aragonite crystals) are compared. The hardness and modulus of lapillus are higher than those of asteriscus both in nano- and micro-testing, which is attributed to the different crystal polymorphs. Both materials exhibit a certain degree of creep, which indicates some time dependence of the mechanical behavior and is attributed to the organic components. The nano-indentation hardnesses are higher than micro-hardnesses for both otoliths, a direct result of the scale dependence of strength; fewer flaws are encountered by the nano than by the microindenter. Copyright © 2012 Elsevier B.V. All rights reserved.

Microindentation as a complementary method for phase identification

Science.gov (United States)

Zupanič, Franc

2011-12-01

This work investigates the possibility of using microindentation as a complementary tool for phase identification, especially in heterogeneous microstructures. Five phases present in alloys Al64Cu23Fe13 and Al94Mn2Be2Cu2 were indented in the microindentation region. A load of 20 mN was found to be convenient for testing because it was too low to produce cracks around indents, yet high enough to avoid too large scattering of the results, occurring at smaller loads. It allowed testing of particles as small as 10 μm in the lateral direction and 3 μm in thickness. Some phases can be distinguished from others by specific characteristics of indentation curves. Otherwise, a single quantitative parameter or combinations of several indentation parameters (defined in EN ISO 14577-1) sufficed. The microindentation can considerably help by phase identification; however, a wider application will require a database, providing indentation properties for a particular phase at different loads and taking into account the indentation size effect.

Micro-hardness of non-irradiated uranium dioxide

International Nuclear Information System (INIS)

Kim, Sung-Sik; Takagi, Osamu; Obata, Naomi; Kirihara, Tomoo.

1983-01-01

In order to obtain the optimum conditions for micro-hardness measurements of sintered UO 2 , two kinds of hardness tests (Vickers and Knoop) were examined with non-irradiated UO 2 of 2.5 and 5 μm in grain size. The hardness values were obtained as a function of the applied load in the load range of 25 -- 1,000 g. In the Vickers test, cracks were generated around the periphery of an indentation even at lower load of 50 g, which means the Vickers hardness is not suitable for UO 2 specimens. In the Knoop test, three stages of load dependence were observed for sintered pellet as well as for a single crystal by Bates. Load dependence of Knoop hardness and crack formation were discussed. In the range of applied load around 70 -- 100 g there were plateau region where hardness values were nearly unchanged and did not contain any cracks in the indentation. The plateau region represents a hardness of a specimen. From a comparison between the hardness values of 2.5 μm and those of 5 μm UO 2 , it was approved that the degree of sintering controls the hardness in the plateau region. (author)

Elasticity and hardness of nano-polycrystalline boron nitrides: The apparent Hall-Petch effect

International Nuclear Information System (INIS)

Nagakubo, A.; Ogi, H.; Hirao, M.; Sumiya, H.

2014-01-01

Nano-polycrystalline boron nitride (BN) is expected to replace diamond as a superhard and superstiff material. Although its hardening was reported, its elasticity remains unclear and the as-measured hardness could be significantly different from the true value due to the elastic recovery. In this study, we measured the longitudinal-wave elastic constant of nano-polycrystalline BNs using picosecond ultrasound spectroscopy and confirmed the elastic softening for small-grain BNs. We also measured Vickers and Knoop hardness for the same specimens and clarified the relationship between hardness and stiffness. The Vickers hardness significantly increased as the grain size decreased, while the Knoop hardness remained nearly unchanged. We attribute the apparent increase in Vickers hardness to the elastic recovery and propose a model to support this insight.

Hardness and thermal stability of cubic silicon nitride

DEFF Research Database (Denmark)

Jiang, Jianzhong; Kragh, Flemming; Frost, D. J.

2001-01-01

The hardness and thermal stability of cubic spinel silicon nitride (c-Si3N4), synthesized under high-pressure and high-temperature conditions, have been studied by microindentation measurements, and x-ray powder diffraction and scanning electron microscopy, respectively The phase at ambient...

Final report on COOMET Vickers PTB/VNIIFTRI key comparison (COOMET.M.H-K1.b and COOMET.M.H-K1.c)

Science.gov (United States)

Aslanyan, E.; Herrmann, K.

2013-01-01

This report describes a COOMET key comparison on Vickers hardness scales of two National Metrology Institutes—PTB and VNIIFTRI. The pilot laboratory was PTB, which was the linking institute with the key comparison reference values of CCM.H-K1. In the key comparison two sets of hardness reference blocks for the Vickers hardness scales HV1 and HV30, each consisting of three hardness reference blocks with the hardness levels 240 HV, 540 HV and 840 HV, are used. The same hardness reference blocks were used previously in the key comparison CCM.H-K1. The measurement results and uncertainty assessments, announced by VNIIFTRI, are in good agreement with the key comparison reference values of CCM.H-K1. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Tungsten tetraboride, an inexpensive superhard material

Science.gov (United States)

Mohammadi, Reza; Lech, Andrew T.; Xie, Miao; Weaver, Beth E.; Yeung, Michael T.; Tolbert, Sarah H.; Kaner, Richard B.

2011-01-01

Tungsten tetraboride (WB4) is an interesting candidate as a less expensive member of the growing group of superhard transition metal borides. WB4 was successfully synthesized by arc melting from the elements. Characterization using powder X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX) indicates that the as-synthesized material is phase pure. The zero-pressure bulk modulus, as measured by high-pressure X-ray diffraction for WB4, is 339 GPa. Mechanical testing using microindentation gives a Vickers hardness of 43.3 ± 2.9 GPa under an applied load of 0.49 N. Various ratios of rhenium were added to WB4 in an attempt to increase hardness. With the addition of 1 at.% Re, the Vickers hardness increased to approximately 50 GPa at 0.49 N. Powders of tungsten tetraboride with and without 1 at.% Re addition are thermally stable up to approximately 400 °C in air as measured by thermal gravimetric analysis. PMID:21690363

Evaluation of thermal aging effect on primary pipe material in nuclear power plant by micro hardness test method

International Nuclear Information System (INIS)

Xue Fei; Yu Weiwei; Wang Zhaoxi; Ma Qinzheng; Liu Wei

2012-01-01

The investigation was carried out on the changes in mechanical properties of the primary pipe material Z3CN20.09M after 10000 h aging at 400℃ by using micro- Vickers and impact testing machine. The results show that the impact energy of testing material decreases. However, the micro-Vickers hardness of ferrite phase and austenite phase which constitute the testing material increase and keep constant, respectively. The intrinsic relations were analyzed between the micro-Vickers hardness and the impact energy to make an attempt to present the micro-Vickers hardness measurement as a method applicable to evaluating the thermal aging of the primary pipe material. (authors)

Mechanical properties of some binary, ternary and quaternary III-V compound semiconductor alloys

International Nuclear Information System (INIS)

Navamathavan, R.; Arivuoli, D.; Attolini, G.; Pelosi, C.; Choi, Chi Kyu

2007-01-01

Vicker's microindentation tests have been carried out on InP/InP, GaAs/InP, InGaAs/InP and InGaAsP/InP III-V compound semiconductor alloys. The detailed mechanical properties of these binary, ternary and quaternary epilayers were determined from the indentation experiments. Microindentation studies of (1 1 1) GaAs/InP both A and B faces show that the hardness value increases with load and attains a constant for further increase in load and the microhardness values were found to lie between 3.5 and 4.0 GPa. The microhardness values of InGaAs/InP epilayers with different thickness were found to lie between 3.93 and 4.312 GPa. The microhardness values of InGaAsP/InP with different elemental composition were found to lie between 5.08 and 5.73 GPa. The results show that the hardness of the quaternary alloy drastically increases, the reason may be that the increase in As concentration hardens the lattice when phosphorous concentration is less and hardness decreases when phosphorous is increased. It was interestingly observed that the hardness value increases as we proceed from binary to quaternary III-V compound semiconductor alloys

Microindentation deformation of lithium dihydrogen phosphate single crystals: Microhardness measurement and indentation size effect

Energy Technology Data Exchange (ETDEWEB)

Iurchenko, Anton [Institute for Single Crystals, National Academy of Sciences of Ukraine, Lenin Avenue 60, 61001 Kharkiv (Ukraine); Borc, Jarosław, E-mail: j.borc@pollub.pl [Department of Applied Physics, Lublin University of Technology, ul. Nadbystrzycka 38, 20-618 Lublin (Poland); Sangwal, Keshra [Department of Applied Physics, Lublin University of Technology, ul. Nadbystrzycka 38, 20-618 Lublin (Poland); Voronov, Alexei [Institute for Single Crystals, National Academy of Sciences of Ukraine, Lenin Avenue 60, 61001 Kharkiv (Ukraine)

2016-02-15

The Vickers microhardness H{sub V} of the (110) and (111) as-grown faces of lithium dihydrogen phosphate (LDP) crystals was investigated as a function of applied load P. The microhardness H{sub V} of the two faces increases with load P i.e. reverse indentation size effect (reverse ISE) and the hardness of the (110) face is somewhat lower than that of the (111) face but this difference is not easily recognized for these planes due to large scatter in the data. The origin of observed ISE was analyzed using different approaches. It was found that: (1) Hays–Kendall's and Begley–Hutchinson's relations do not explain the origin of reverse ISE but Meyer's law describes the reverse ISE satisfactorily and its constants provide a link between ISE and formation of radial cracks with applied indentation load P, (2) reverse ISE is associated with tensile surface stresses, (3) despite its failure to explain reverse ISE, Begley–Hutchinson's relation is reliable to obtain load-independent hardness H{sub 0}, is 2337 MPa for LDP, and (4) the value of fracture toughness K{sub C} of LDP crystals lies between 4.7 and 12 MPa m{sup 1/2}. The load-independent hardness H{sub 0} of LDP is higher by a factor of 1.5 than that reported for undoped KDP and ADP crystals whereas its fracture toughness K{sub C} is higher by factor of about 20 than that of undoped KDP crystals. - Highlights: • Vickers indentations on the (110) and (111) faces of LDP crystals were made. • The microhardness H{sub V} was investigated as a function of applied load P. • Reverse indentation size effect was observed. • Fracture toughness K{sub C} from the radial cracks was calculated.

Microindentation deformation of lithium dihydrogen phosphate single crystals: Microhardness measurement and indentation size effect

International Nuclear Information System (INIS)

Iurchenko, Anton; Borc, Jarosław; Sangwal, Keshra; Voronov, Alexei

2016-01-01

The Vickers microhardness H_V of the (110) and (111) as-grown faces of lithium dihydrogen phosphate (LDP) crystals was investigated as a function of applied load P. The microhardness H_V of the two faces increases with load P i.e. reverse indentation size effect (reverse ISE) and the hardness of the (110) face is somewhat lower than that of the (111) face but this difference is not easily recognized for these planes due to large scatter in the data. The origin of observed ISE was analyzed using different approaches. It was found that: (1) Hays–Kendall's and Begley–Hutchinson's relations do not explain the origin of reverse ISE but Meyer's law describes the reverse ISE satisfactorily and its constants provide a link between ISE and formation of radial cracks with applied indentation load P, (2) reverse ISE is associated with tensile surface stresses, (3) despite its failure to explain reverse ISE, Begley–Hutchinson's relation is reliable to obtain load-independent hardness H_0, is 2337 MPa for LDP, and (4) the value of fracture toughness K_C of LDP crystals lies between 4.7 and 12 MPa m"1"/"2. The load-independent hardness H_0 of LDP is higher by a factor of 1.5 than that reported for undoped KDP and ADP crystals whereas its fracture toughness K_C is higher by factor of about 20 than that of undoped KDP crystals. - Highlights: • Vickers indentations on the (110) and (111) faces of LDP crystals were made. • The microhardness H_V was investigated as a function of applied load P. • Reverse indentation size effect was observed. • Fracture toughness K_C from the radial cracks was calculated.

Study of microcracks morphology produced by Vickers indentation on AISI 1045 borided steels

International Nuclear Information System (INIS)

Campos, I.; Ramirez, G.; VillaVelazquez, C.; Figueroa, U.; Rodriguez, G.

2008-01-01

In this work, we analyzed the roughness morphology of indentation microcracks produced by the Vickers microindentation in the iron boride Fe 2 B. Using the paste boriding process, the boride layers were formed at the surface of AISI 1045 steels. The diffusion processes were carried out with 5 mm of boron paste thickness over the substrate surface at three different temperatures (1193, 1223 and 1273 K) with two different time exposures. The indentations in each Fe 2 B layer were made using a constant load of 200 g at four different distances from the surface. The fracture behavior of the Fe 2 B borided phase is found to be brittle in nature. The profiles of microcracks formed at the corners of the indentations were obtained using the scanning electronic microscopy and were analyzed within the framework of fractal geometry. We found that all indentation microcracks display a self-affine invariance characterized by the same roughness (Hurst) exponent H = 0.8 ± 0.1. The effect of the self-affine roughness of indentation microcracks on the measured fracture toughness is discussed within the framework of the mechanics of self-affine cracks. It is pointed out that the arrest of indentation microcracks is controlled by the fractal fracture toughness, which for the Fe 2 B borided phase is found to be K fc = 0.42 ± 0.02 MPa m 0.75 at all distances from the surface

Microindentation test for determining mechanical properties of corroded layers of ceramics

International Nuclear Information System (INIS)

Wakui, Takashi; Futakawa, Masatoshi; Tanabe, Yuji; Eto, Motokuni

1999-01-01

Microindentation tests on ceramics (Si-SiC, SiC, Al 2 O 3 and Si 3 N 4 ) immersed in boiling 95 wt% sulfuric acid for 100 or 1000 hours were performed to evaluate the mechanical properties of their corroded layers. The thickness (T) of corroded layer on ceramics was evaluated in terms of characteristic depth (d) which was determined from the point of inflection on the Depth-Load/Depth curve by the microindentation test. The relationship between T and d was found to be given as T nearly equal 10d. Finite element analyses were performed to validate the relationship and to clarify the effects of mechanical properties of corroded layer and the indenter tip radius on the relationship as well. The mechanical properties [Young's modulus (E f ) and yield stress (σ yf )] of corroded layers of Al 2 O 3 and Si 3 N 4 were identified by fitting the predicted Depth-Load/Depth curve to the experimental data. (author)

Extracorporeal shockwave enhanced regeneration of fibrocartilage in a delayed tendon-bone insertion repair model.

Science.gov (United States)

Chow, Dick Ho Kiu; Suen, Pui Kit; Huang, Le; Cheung, Wing-Hoi; Leung, Kwok-Sui; Ng, Chun; Shi, San Qiang; Wong, Margaret Wan Nar; Qin, Ling

2014-04-01

Fibrous tissue is often formed in delayed healing of tendon bone insertion (TBI) instead of fibrocartilage. Extracorporeal shockwave (ESW) provides mechanical cues and upregulates expression of fibrocartilage-related makers and cytokines. We hypothesized that ESW would accelerate fibrocartilage regeneration at the healing interface in a delayed TBI healing model. Partial patellectomy with shielding at the TBI interface was performed on 32 female New Zealand White Rabbits for establishing this delayed TBI healing model. The rabbits were separated into the control and ESW group for evaluations at postoperative week 8 and 12. Shielding was removed at week 4 and a single ESW treatment was applied at week 6. Fibrocartilage regeneration was evaluated histomorphologically and immunohistochemically. Vickers hardness of the TBI matrix was measured by micro-indentation. ESW group showed higher fibrocartilage area, thickness, and proteoglycan deposition than the control in week 8 and 12. ESW increased expression of SOX9 and collagen II significantly in week 8 and 12, respectively. ESW group showed a gradual transition of hardness from bone to fibrocartilage to tendon, and had a higher Vickers hardness than the control group at week 12. In conclusion, ESW enhanced fibrocartilage regeneration at the healing interface in a delayed TBI healing model. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Hardness properties and microscopic investigation of crack- crystal interaction in SiO(2)-MgO-Al(2)O(3)-K(2)O-B(2)O(3)-F glass ceramic system.

Science.gov (United States)

Roy, Shibayan; Basu, Bikramjit

2010-01-01

In view of the potential engineering applications requiring machinability and wear resistance, the present work focuses to evaluate hardness property and to understand the damage behavior of some selected glass-ceramics having different crystal morphologies with SiO(2)-MgO-Al(2)O(3)-K(2)O-B(2)O(3)-F composition, using static micro-indentation tests as well as dynamic scratch tests, respectively. Vickers hardness of up to 5.5 GPa has been measured in glass-ceramics containing plate like mica crystals. Scratch tests at a high load of 50 Nin artificial saliva were carried out in order to simulate the crack-microstructure interaction during real-time abrasion wear and machining operation. The experimental observations indicate that the novel "spherulitic-dendritic shaped "crystals, similar to the plate like crystals, have the potential to hinder the scratching induced crack propagation. In particular, such potential of the 'spherulitic-dendritic' crystals become more effective due to the larger interfacial area with the glass matrix as well as the dendritic structure of each mica plate, which helps in crack deflection and crack blunting, to a larger extent.While modest damage tolerant behavior is observed in case of 'spherulitic-dendritic' crystal containing material, severe brittle fracture of plate like crystals were noted, when both were scratched at 50 N load.

Evaluating microhardness of plasma sprayed Al2O3 coatings using Vickers indentation technique

International Nuclear Information System (INIS)

Yin Zhijian; Tao Shunyan; Zhou Xiaming; Ding Chuanxian

2007-01-01

In this work, the microhardness of plasma sprayed Al 2 O 3 coatings was evaluated using the Vickers indentation technique, and the effects of measurement direction, location and applied loads were investigated. The measured data sets were then statistically analysed employing the Weibull distribution to evaluate their variability within the coatings. It was found that the Vickers hardness (VHN) increases with decreasing applied indenter load, which can be explained in terms of Kick's law and the Meyer index k of 1.93, as well as relating to the microstructural characteristics of plasma sprayed coatings and the elastic recovery taking place during indentation. In addition, VHN, measured on the cross section of coatings, was obviously higher than that on its top surface. The obtained Weibull modulus and variation coefficient indicate that the VHN was less variable when measured at a higher applied load and on the cross section of coating. The obvious dependence of the VHN on the specific indentation location within through-thickness direction was also realized. These phenomena described above in this work were related to the special microstructure and high anisotropic behaviour of plasma sprayed coatings

Hardness of basaltic glass-ceramics

DEFF Research Database (Denmark)

Jensen, Martin; Smedskjær, Morten Mattrup; Estrup, Maja

2009-01-01

The dependence of the hardness of basaltic glass-ceramics on their degree of crystallisation has been explored by means of differential scanning calorimetry, optical microscopy, x-ray diffraction, and Vickers indentation. Different degrees of crystallisation in the basaltic glasses were achieved...... by varying the temperature of heat treatment. The predominant crystalline phase in the glass was identified as augite. It was found that the hardness of the glass phase decreased slightly with an increase in the degree of crystallisation, while that of the augite phase drastically decreased....

The influence of material hardness on liquid droplet impingement erosion

International Nuclear Information System (INIS)

Fujisawa, Nobuyuki; Yamagata, Takayuki; Takano, Shotaro; Saito, Kengo; Morita, Ryo; Fujiwara, Kazutoshi; Inada, Fumio

2015-01-01

Highlights: • Liquid droplet impingement erosion is studied for various metal materials. • Average power dependency on droplet velocity is found as 7. • Power dependency on Vickers hardness is found as −4.5. • An empirical formula is constructed for erosion rates of metal materials. • Predicted erosion rate is well correlated with experiment within a factor of 1.5. - Abstract: This paper describes the experimental study on the liquid droplet impingement erosion of metal materials to understand the influence of material hardness on the erosion rate. The experiment is carried out using a water spray jet apparatus with a condition of relatively thin liquid film thickness. The metal materials tested are pure aluminum, aluminum alloy, brass, mild steel, carbon steel and stainless steel. The liquid droplets considered are 30 ± 5 μm in volume average diameter of water, which is the same order of droplet diameter in the actual pipeline in nuclear/fossil power plants. In order to understand the influence of material hardness on the liquid droplet impingement erosion, the scanning electron microscope (SEM) observation on the eroded surface and the measurement of erosion rate are carried out in the terminal stage of erosion. The experimental results indicate that the erosion rates are expressed by the droplet velocity, volume flux, Vickers hardness and the liquid film thickness, which are fundamentals of the liquid droplet impingement erosion. The empirical formula shows that the power index for droplet velocity dependency is found to be 7 with a scattering from 5 to 9 depending on the materials, while the power index for Vickers hardness dependency is found as −4.5

The influence of material hardness on liquid droplet impingement erosion

Energy Technology Data Exchange (ETDEWEB)

Fujisawa, Nobuyuki, E-mail: fujisawa@eng.niigata-u.ac.jp [Visualization Research Center, Niigata University, 8050, Ikarashi 2-Nocho, Nishi-ku, Niigata 950-2181 (Japan); Yamagata, Takayuki, E-mail: yamagata@eng.niigata-u.ac.jp [Visualization Research Center, Niigata University, 8050, Ikarashi 2-Nocho, Nishi-ku, Niigata 950-2181 (Japan); Takano, Shotaro; Saito, Kengo [Graduate School of Science and Technology, Niigata University, 8050, Ikarashi 2-Nocho, Nishi-ku, Niigata 950-2181 (Japan); Morita, Ryo; Fujiwara, Kazutoshi; Inada, Fumio [Central Research Institute of Electric Power Industry, 2-11-1, Iwatokita, Komae, Tokyo 201-8511 (Japan)

2015-07-15

Highlights: • Liquid droplet impingement erosion is studied for various metal materials. • Average power dependency on droplet velocity is found as 7. • Power dependency on Vickers hardness is found as −4.5. • An empirical formula is constructed for erosion rates of metal materials. • Predicted erosion rate is well correlated with experiment within a factor of 1.5. - Abstract: This paper describes the experimental study on the liquid droplet impingement erosion of metal materials to understand the influence of material hardness on the erosion rate. The experiment is carried out using a water spray jet apparatus with a condition of relatively thin liquid film thickness. The metal materials tested are pure aluminum, aluminum alloy, brass, mild steel, carbon steel and stainless steel. The liquid droplets considered are 30 ± 5 μm in volume average diameter of water, which is the same order of droplet diameter in the actual pipeline in nuclear/fossil power plants. In order to understand the influence of material hardness on the liquid droplet impingement erosion, the scanning electron microscope (SEM) observation on the eroded surface and the measurement of erosion rate are carried out in the terminal stage of erosion. The experimental results indicate that the erosion rates are expressed by the droplet velocity, volume flux, Vickers hardness and the liquid film thickness, which are fundamentals of the liquid droplet impingement erosion. The empirical formula shows that the power index for droplet velocity dependency is found to be 7 with a scattering from 5 to 9 depending on the materials, while the power index for Vickers hardness dependency is found as −4.5.

Time-dependent mechanical characteristics measured through the use of a microindentation technique

Czech Academy of Sciences Publication Activity Database

Minster, Jiří; Bláhová, O.; Lukeš, J.; Němeček, J.

2010-01-01

Roč. 14, č. 3 (2010), s. 243-251 ISSN 1385-2000 R&D Projects: GA AV ČR(CZ) IAA200710801 Institutional research plan: CEZ:AV0Z20710524 Keywords : materials testing * microindentation * viscoelastic compliance * relaxation modulus Subject RIV: JI - Composite Materials Impact factor: 0.955, year: 2010

Degree of conversion and surface hardness of resin cement cured with different curing units.

Science.gov (United States)

Ozturk, Nilgun; Usumez, Aslihan; Usumez, Serdar; Ozturk, Bora

2005-01-01

The aim of this study was to evaluate the degree of conversion and Vickers surface hardness of resin cement under a simulated ceramic restoration with 3 different curing units: a conventional halogen unit, a high-intensity halogen unit, and a light-emitting diode system. A conventional halogen curing unit (Hilux 550) (40 s), a high-intensity halogen curing unit used in conventional and ramp mode (Optilux 501) (10 s and 20 s, respectively), and a light-emitting diode system (Elipar FreeLight) (20 s, 40 s) were used in this study. The dual-curing resin cement (Variolink II) was cured under a simulated ceramic restoration (diameter 5 mm, height 2 mm), and the degree of conversion and Vickers surface hardness were measured. For degree of conversion measurement, 10 specimens were prepared for each group. The absorbance peaks were recorded using the diffuse-reflection mode of Fourier transformation infrared spectroscopy. For Vickers surface hardness measurement, 10 specimens were prepared for each group. A load of 200 N was applied for 15 seconds, and 3 evaluations of each of the samples were performed. Degree of conversion achieved with Optilux 501 (20 s) was significantly higher than those of Hilux, Optilux 501 (10 s), Elipar FreeLight (20 s), and Elipar FreeLight (40 s). For Vickers surface hardness measurement, Optilux 501 (20 s) produced the highest surface hardness value. No significant differences were found among the Hilux, Optilux 501 (10 s), Elipar FreeLight (20 s), and Elipar FreeLight (40 s). The high-intensity halogen curing unit used in ramp mode (20 s) produced harder resin cement surfaces than did the conventional halogen curing unit, high-intensity halogen curing unit used in conventional mode (10 s) and light-emitting diode system (20 s, 40 s), when cured through a simulated ceramic restoration.

Development of 3d micro-nano hybrid patterns using anodized aluminum and micro-indentation

International Nuclear Information System (INIS)

Shin, Hong Gue; Kwon, Jong Tae; Seo, Young Ho; Kim, Byeong Hee

2008-01-01

We developed a simple and cost-effective method of fabricating 3D micro-nano hybrid patterns in which micro-indentation is applied on the anodized aluminum substrate. Nano-patterns were formed first on the aluminum substrate, and then micro-patterns were fabricated by deforming the nano-patterned aluminum substrate. Hemispherical nano-patterns with a 150 nm-diameter on an aluminum substrate were fabricated by anodizing and alumina removing process. Then, micro-pyramid patterns with a side-length of 50 μm were formed on the nano-patterns using micro-indentation. To verify 3D micro-nano hybrid patterns, we replicated 3D micro-nano hybrid patterns by a hot-embossing process. 3D micro-nano hybrid patterns may be used in nano-photonic devices and nano-biochips applications

Development of 3d micro-nano hybrid patterns using anodized aluminum and micro-indentation

Energy Technology Data Exchange (ETDEWEB)

Shin, Hong Gue; Kwon, Jong Tae [Division of Mechanical Engineering and Mechatronics, Kangwon National University, 1 Kangwondaehakgil, Chunchon, Gangwon-do, 200-701 (Korea, Republic of); Seo, Young Ho [Division of Mechanical Engineering and Mechatronics, Kangwon National University, 1 Kangwondaehakgil, Chunchon, Gangwon-do, 200-701 (Korea, Republic of)], E-mail: mems@kangwon.ac.kr; Kim, Byeong Hee [Division of Mechanical Engineering and Mechatronics, Kangwon National University, 1 Kangwondaehakgil, Chunchon, Gangwon-do, 200-701 (Korea, Republic of)

2008-07-31

We developed a simple and cost-effective method of fabricating 3D micro-nano hybrid patterns in which micro-indentation is applied on the anodized aluminum substrate. Nano-patterns were formed first on the aluminum substrate, and then micro-patterns were fabricated by deforming the nano-patterned aluminum substrate. Hemispherical nano-patterns with a 150 nm-diameter on an aluminum substrate were fabricated by anodizing and alumina removing process. Then, micro-pyramid patterns with a side-length of 50 {mu}m were formed on the nano-patterns using micro-indentation. To verify 3D micro-nano hybrid patterns, we replicated 3D micro-nano hybrid patterns by a hot-embossing process. 3D micro-nano hybrid patterns may be used in nano-photonic devices and nano-biochips applications.

Evaluation of Polymerization Efficacy in Composite Resins via FT-IR Spectroscopy and Vickers Microhardness Test

Directory of Open Access Journals (Sweden)

Tahereh-Sadat Jafarzadeh

2015-12-01

Full Text Available Background and aims. Polymerization efficacy affects the properties and performance of composite resin restorations.The purpose of this study was to evaluate the effectiveness of polymerization of two micro-hybrid, two nano-hybrid and one nano-filled ormocer-based composite resins, cured by two different light-curing systems, using Fourier transformation infrared (FT-IR spectroscopy and Vickers microhardness testing at two different depths (top surface, 2 mm. Materials and methods. For FT-IR spectrometry, five cylindrical specimens (5mm in diameter × 2 mm in length were prepared from each composite resin using Teflon molds and polymerized for 20 seconds. Then, 70-μm wafers were sectioned at the top surface and at2mm from the top surface. The degree of conversion for each sample was calculated using FT-IR spectroscopy. For Vickers micro-hardness testing, three cylindrical specimens were prepared from each composite resin and polymerized for 20 seconds. The Vickers microhardness test (Shimadzu, Type M, Japan was performed at the top and bottom (depth=2 mm surfaces of each specimen. Three-way ANOVA with independent variables and Tukey tests were performed at 95% significance level. Results. No significant differences were detected in degree of conversion and microhardness between LED and QTH light-curing units except for the ormocer-based specimen, CeramX, which exhibited significantly higher DC by LED. All the composite resins showed a significantly higher degree of conversion at the surface. Microhardness was not significantly affected by depth, except for Herculite XRV Ultra and CeramX, which showed higher values at the surface. Conclusion. Composite resins containing nano-particles generally exhibited more variations in degree of conversion and microhardness.

Evaluation of Polymerization Efficacy in Composite Resins via FT-IR Spectroscopy and Vickers Microhardness Test.

Science.gov (United States)

Jafarzadeh, Tahereh-Sadat; Erfan, Mohammad; Behroozibakhsh, Marjan; Fatemi, Mostafa; Masaeli, Reza; Rezaei, Yashar; Bagheri, Hossein; Erfan, Yasaman

2015-01-01

Background and aims. Polymerization efficacy affects the properties and performance of composite resin restorations.The purpose of this study was to evaluate the effectiveness of polymerization of two micro-hybrid, two nano-hybrid and one nano-filled ormocer-based composite resins, cured by two different light-curing systems, using Fourier transformation infrared (FT-IR) spectroscopy and Vickers microhardness testing at two different depths (top surface, 2 mm). Materials and methods. For FT-IR spectrometry, five cylindrical specimens (5mm in diameter × 2 mm in length) were prepared from each composite resin using Teflon molds and polymerized for 20 seconds. Then, 70-μm wafers were sectioned at the top surface and at2mm from the top surface. The degree of conversion for each sample was calculated using FT-IR spectroscopy. For Vickers micro-hardness testing, three cylindrical specimens were prepared from each composite resin and polymerized for 20 seconds. The Vickers microhardness test (Shimadzu, Type M, Japan) was performed at the top and bottom (depth=2 mm) surfaces of each specimen. Three-way ANOVA with independent variables and Tukey tests were performed at 95% significance level. Results. No significant differences were detected in degree of conversion and microhardness between LED and QTH light-curing units except for the ormocer-based specimen, CeramX, which exhibited significantly higher DC by LED. All the composite resins showed a significantly higher degree of conversion at the surface. Microhardness was not significantly affected by depth, except for Herculite XRV Ultra and CeramX, which showed higher values at the surface. Conclusion. Composite resins containing nano-particles generally exhibited more variations in degree of conversion and microhardness.

Influence of 1,3,6 naphthalene trisulfonic acid on microstructure & hardness in electrodeposited Ni-layers

DEFF Research Database (Denmark)

Rasmussen, Anette Alsted; Møller, Per; Somers, Marcel A. J.

2002-01-01

The influence of the additive 1,3,6 naphthalene trisulfonic acid on the microstructure and hardness of electrodeposited nickel layers was investigated. The microstructure was characterized using transmission electron microscopy; the Vickers hardness was measured in cross sections. The additive wa...

Temperature-dependent microindentation data of an epoxy composition in the glassy region

Czech Academy of Sciences Publication Activity Database

Minster, Jiří; Králík, V.

2015-01-01

Roč. 19, č. 1 (2015), s. 75-85 ISSN 1385-2000 R&D Projects: GA ČR(CZ) GAP105/12/0824 Institutional support: RVO:68378297 Keywords : mechanical properties * viscoelasticity * glass transition * microindentation * time-temperature superposition Subject RIV: JI - Composite Materials Impact factor: 1.120, year: 2015 http://link.springer.com/article/10.1007/s11043-014-9252-6

Cathodoluminescence study of vickers indentations in magnesium ...

African Journals Online (AJOL)

Vickers diamond pyramid indentations made in single crystal of magnesium oxide (MgO) were examined in an environmental scanning electron microscope interfaced with an AVS-2000 spectrophotometer for luminescence. Three distinct zones around the indentations were identified to exhibit cathodoluminescence, which ...

Micromechanical Behavior of Single-Crystal Superalloy with Different Crystal Orientations by Microindentation

Directory of Open Access Journals (Sweden)

Jinghui Li

2015-01-01

Full Text Available In order to investigate the anisotropic micromechanical properties of single-crystal nickel-based superalloy DD99 of four crystallographic orientations, (001, (215, (405, and (605, microindentation test (MIT was conducted with different loads and loading velocities by a sharp Berkovich indenter. Some material parameters reflecting the micromechanical behavior of DD99, such as microhardness H, Young’s modulus E, yield stress σy, strain hardening component n, and tensile strength σb, can be obtained from load-displacement relations. H and E of four different crystal planes evidently decrease with the increase of h. The reduction of H is due to dislocation hardening while E is related to interplanar spacing and crystal variable. σy of (215 is the largest among four crystal planes, followed by (605, and (001 has the lowest value. n of (215 is the lowest, followed by (605, and that of (001 is the largest. Subsequently, a simplified elastic-plastic material model was employed for 3D microindentation simulation of DD99 with various crystal orientations. The simulation results agreed well with experimental, which confirmed the accuracy of the simplified material model.

Role of elastic deformation in determining the mixed alkaline earth effect of hardness in silicate glasses

DEFF Research Database (Denmark)

Kjeldsen, Jonas; Smedskjær, Morten Mattrup; Potuzak, M.

2015-01-01

been investigated previously, but the link between the resistance to elastic deformation and hardness has not yet been studied. In this work, we investigate the link between elastic deformation during indentation and Vickers hardness in a series of mixed magnesium-barium boroaluminosilicate glasses. We...

The relationship between vickers microhardness and compressive strength of functional surface geopolymers

Science.gov (United States)

Subaer, Ekaputri, Januari Jaya; Fansuri, Hamzah; Abdullah, Mustafa Al Bakri

2017-09-01

An experimental study to investigate the relationship between Vickers microhardness and compressive strength of geopolymers made from metakaolin has been conducted. Samples were prepared by using metakaolin activated with a sodium silicate solution at a different ratio of Si to Al and Na to Al and cured at 70oC for one hour. The resulting geopolymers were stored in an open air for 28 days before conducting any measurement. Bulk density and apparent porosity of the samples were measured by using Archimedes's method. Vickers microhardness measurements were performed on a polished surface of geopolymers with a load ranging from 0.3 - 1.0 kg. The topographic of indented samples were examined by using scanning electron microscopy (SEM). Compressive strength of the resulting geopolymers was measured on the cylindrical samples with a ratio of height to the diameter was 2:1. The results showed that the molar ratios of geopolymers compositions play important roles in the magnitude of bulk density, porosity, Vickers's microhardness as well as the compressive strength. The porosity reduced exponentially the magnitude of the strength of geopolymers. It was found that the relationship between Vickers microhardness and compressive strength was linear. At the request of all authors and with the approval of the proceedings editor, article 020188 titled, "The relationship between vickers microhardness and compressive strength of functional surface geopolymers," is being retracted from the public record due to the fact that it is a duplication of article 020170 published in the same volume.

Evaluation and Comparison of the Effects of RRA, T73 and T6 Heat Treatments on Hardness, Tensile and Bending Strengths of 7075 Aluminum Alloy

Directory of Open Access Journals (Sweden)

M. Assadi

2016-09-01

20 min and in the third stage aging process was repeated like T6 treatment. Evaluation of the microstructures and fractured surfaces were performed with optical microscopes (OM and scanning electron microscopes (SEM. Energy dispersive spectroscopy (EDS was used to study the chemical composition of precipitates. Hardness, tensile and bending strength were evaluated according to ASTM E384-11e1, ASTM B557-06 and DIN 50121 standards. RRA treatment increased tensile strength from 466 to 485 MPa and hardness from 110 to 165 Vickers. After T6 treatment, tensile strength increased from 466 to 505 MPa and hardness from 110 to 160 Vickers. In T73 process, the tensile strength remained almost constant (465 MPa but yield strength increased from 394 to 410 MPa and hardness decreased from 110 to 84 Vickers. The bending strength increased from 797 to 844, 920 and 1030 MPa in T73, RRA and T6 processes, respectively. By applying RRA process in optimized temperature and time, hardness, tensile and bending strengths of 7075 aluminum alloy were enhanced from 5 to 15% compared to that of T6 and T73 processes.

The hardness of synthetic products obtained from cooled and crystallized basaltic melts (in Romanian)

OpenAIRE

Daniela Ogrean

2001-01-01

The Hardness of Synthetic Products Obtained from Cooled and Crystallized Basaltic Melts. Hardness is one of the main properties of the products obtained from cooled and crystallized basaltic melts under a controlled thermal regime. It influences the abrasion tear resistance of the resulted material. The microhardness measurements on the samples (bricks, boards, gutters, armour plates, tubes) indicated Vickers hardness value between 757–926 for the materials obtained from Şanovita basalts (Tim...

Crystallographic Analysis of Nucleation at Hardness Indentations in High-Purity Aluminum

DEFF Research Database (Denmark)

Xu, Chaoling; Zhang, Yubin; Lin, Fengxiang

2016-01-01

Nucleation at Vickers hardness indentations has been studied in high-purity aluminum cold-rolled 12 pct. Electron channeling contrast was used to measure the size of the indentations and to detect nuclei, while electron backscattering diffraction was used to determine crystallographic orientations....... It is found that indentations are preferential nucleation sites. The crystallographic orientations of the deformed grains affect the hardness and the nucleation potentials at the indentations. Higher hardness gives increased nucleation probabilities. Orientation relationships between nuclei developed...... they form. Finally, possible nucleation mechanisms are briefly discussed....

Characterization of titanium aluminide alloy components fabricated by additive manufacturing using electron beam melting

International Nuclear Information System (INIS)

Murr, L.E.; Gaytan, S.M.; Ceylan, A.; Martinez, E.; Martinez, J.L.; Hernandez, D.H.; Machado, B.I.; Ramirez, D.A.; Medina, F.; Collins, S.; Wicker, R.B.

2010-01-01

Intermetallic, γ-TiAl, equiaxed, small-grain (∼2 μm) structures with lamellar γ/α 2 -Ti 3 Al colonies with average spacing of 0.6 μm have been fabricated by additive manufacturing using electron beam melting (EBM) of precursor, atomized powder. The residual microindentation (Vickers) hardness (HV) averaged 4.1 GPa, corresponding to a nominal yield strength of ∼1.4 GPa (∼HV/3), and a specific yield strength of 0.37 GPa cm 3 g -1 (for a density of 3.76 g cm -3 ), in contrast to 0.27 GPa cm 3 g -1 for EBM-fabricated Ti-6Al-4V components. These results demonstrate the potential to fabricate near net shape and complex titanium aluminide products directly using EBM technology in important aerospace and automotive applications.

Surface roughness and hardness of yttria stabilized zirconia (Y-TZP after 10 years of simulated brushing

Directory of Open Access Journals (Sweden)

Lucas Miguel Candido

Full Text Available Introduction: The Y-TZP zirconia used for prosthetic infrastructure, in some clinical situations, can be exposed to the oral environment. In these situations, a polished surface without changes is extremely important. Objective: The aim of this study was to evaluate the mean roughness (Ra and Vickers hardness of Y-TZP zirconia (Lava™ after simulating ten years of brushing. Material and method: Thirty-six Y-TZP bar-shaped specimens (20mm X 4mm X 1.2mm were divided into three groups: storage in distilled water (DW, n=12, control; brushing with distilled water (BDW, n=12 and brushing with distilled water and fluoride toothpaste (BFT, n=12. Brushing was performed using a brushing machine with a soft-bristled toothbrush, simulating 10 years of brushing (878.400 cycles, 100gf. The mean roughness (Ra in μm and Vickers hardness (VHN of all specimens were measured twice: before and after the experimental treatment, in profilometer and microhardness tester (500gf, 30 seconds, respectively. Data were analyzed using the two-way ANOVA test (α = 0.05. Result: The interaction between groups was not significant for roughness (p = 0.701 nor for hardness (p = 0.928. The final averages for Ra (μm were equal to: DW - 0.63; BDW - 0.64; and, BFT - 0.68. The final averages for Vickers hardness (VHN were: DW - 1301.16; BDW - 1316.60; and, BFT - 1299.58. Conclusion: It was concluded that the brushing with distilled or fluoridated toothpaste was not able to change the roughness and hardness of Y-TZP zirconia used in this study.

Correlation between Fe–V–C alloys surface hardness and plasma temperature via LIBS technique

Energy Technology Data Exchange (ETDEWEB)

Messaoud Aberkane, S., E-mail: smessaoud@cdta.dz [Centre de Développement des Technologies Avancées, Baba Hassen, Alger (Algeria); Bendib, A. [Université des Sciences et de Technologie Houari Boumediene, Bab-Ezzouar, Alger (Algeria); Yahiaoui, K.; Boudjemai, S.; Abdelli-Messaci, S.; Kerdja, T. [Centre de Développement des Technologies Avancées, Baba Hassen, Alger (Algeria); Amara, S.E. [Université des Sciences et de Technologie Houari Boumediene, Bab-Ezzouar, Alger (Algeria); Harith, M.A. [National Institute of Laser Enhanced Science, Cairo University (Egypt)

2014-05-01

Highlights: • New application of LIBS in industry. • Hardness of metallic alloys estimation using LIBS calibration curves. • Linear correlation between the plasma temperature and the hardness of metallic alloys. • The shock wave is fast when the material is hard. - Abstract: Surface hardness is a very important characteristic of metals. Its monitoring plays a key role in industry. In the present paper, using laser induced breakdown spectroscopy (LIBS), Fe–V{sub 18%}–C{sub 1%} alloys with different heat treatments have been used for making the correlation between surface hardness and laser-induced plasma temperatures. All investigated samples were characterized by the same ferrite phase with different Vickers surface hardnesses. The differences in hardness values were attributed to the crystallite size changes. A linear relationship has been obtained between the Vickers surface hardness and the laser induced plasma temperature. For comparison the relation between surface hardness and the ratio of the vanadium ionic to atomic spectral lines intensities (VII/VI) provided good linear results too. However, adopting the proposed approach of using the plasma temperature, instead, is more reliable in view of the difficulties that could be encountered in choosing the proper ionic and atomic spectral lines. To validate this approach we have investigated the shock wave speed induced by laser interaction with the used samples. It was found that harder is the material faster is the shock wave. The determination of the surface hardness via measuring T{sub e} shows the feasibility of using LIBS as an easy and reliable method for in situ industrial application for production control.

Scratch Hardness and Wear Performance of Laser-Melted Steels : Effects of Anisotropy

NARCIS (Netherlands)

Beurs, H. de; Minholts, G.; Hosson, J.Th.M. De

Effects of the orientation of dendrites on the scratch hardness and wear performance of laser-melted steels have been investigated. Scratch experiments have been carried out with a Vickers indenter and wear experiments with a pin-on-disk tester. The deformed structure is investigated, using

Evaluation of hot hardness, creep, fatigue and fracture properties of zirconia ceramics by an indentation technique

International Nuclear Information System (INIS)

Kutty, T.R.G.; Ganguly, C.; Upadhyaya, D.D.

1996-01-01

Zirconia ceramics have wide range engineering applications at room and elevated temperatures. For understanding the mechanical behaviour, the indentation technique was adapted for quick evaluation of hot hardness, creep, fatigue and fracture properties. A Vicker's diamond indentor with 10 N load was employed for hot hardness and creep measurement up to 1300 deg. The fatigue data were evaluated at room temperature by repeated indentation with a constant load (10-2500N) at the same location for a dwell time of 5s until it resulted in the formation of a lateral chip on the sample surface. Thus, the number of cycles for chip formation at a specific indentation load was obtained. The fracture toughness was evaluated at room temperature with a load of 300N using a Vicker's diamond indentor. The results of hot hardness, creep, fatigue, and fracture data ol 3Y-TZP and Mg-PSZ are discussed along with their microstructural features. (authors)

Numerical simulation of flat-tip micro-indentation of glassy polymers: influence of loading speed and thermodynamic state

NARCIS (Netherlands)

Breemen, van L.C.A.; Engels, T.A.P.; Pelletier, C.G.N.; Govaert, L.E.; Toonder, den J.M.J.

2009-01-01

Flat-tip micro-indentation tests were performed on quenched and annealed polymer glasses at various loading speeds. The results were analyzed using an elasto-viscoplastic constitutive model that captures the intrinsic deformation characteristics of a polymer glass: a strain-rate dependent yield

Hot hardness studies on zircaloy 2 pressure tube along three orientations

International Nuclear Information System (INIS)

Kutty, T.R.G.; Ravi, K.; Jarvis, T.; Sengupta, A.K.; Majumdar, S.; Tewari, R.; Shrivastava, D.; Dey, G.K.

2002-01-01

Zirconium based alloys are the natural choice for both the fuel element cans and in-core structural components in water cooled nuclear reactors. In this paper, the hot hardness behaviour of zircaloy 2 pressure tubes has been examined from room temperature to 400 degC using a hot hardness tester. For the purpose of comparison, the hardness of the as cast and room temperature rolled specimens has also been carried out. For this, the samples were cut along three orientations and hardness was measured in each of these directions using Vickers diamond pyramid indenter. The variation in hardness of the pressure tube samples show that the hardness was highest along circumferential direction and least along the axial direction. The room temperature rolled samples showed highest hardness along the rolling planes. These variations in hardness could be explained in terms of development of texture during working on the material. (author)

Ceramic tools insert assesment based on vickers indentation methodology

Science.gov (United States)

Husni; Rizal, Muhammad; Aziz M, M.; Wahyu, M.

2018-05-01

In the interrupted cutting process, the risk of tool chipping or fracture is higher than continues cutting. Therefore, the selection of suitable ceramic tools for interrupted cutting application become an important issue to assure that the cutting process is running effectively. At present, the performance of ceramics tools is assessed by conducting some cutting tests, which is required time and cost consuming. In this study, the performance of ceramic tools evaluated using hardness tester machine. The technique, in general, has a certain advantage compare with the more conventional methods; the experimental is straightforward involving minimal specimen preparation and the amount of material needed is small. Three types of ceramic tools AS10, CC650 and K090 have been used, each tool was polished then Vickers indentation test were performed with the load were 0.2, 0.5, 1, 2.5, 5 and 10 kgf. The results revealed that among the load used in the tests, the indentation loads of 5 kgf always produce well cracks as compared with others. Among the cutting tool used in the tests, AS10 has produced the shortest crack length and follow by CC 670, and K090. It is indicated that the shortest crack length of AS10 reflected that the tool has a highest dynamic load resistance among others insert.

Applications of NTNU/SINTEF Drillability Indices in Hard Rock Tunneling

Science.gov (United States)

Zare, S.; Bruland, A.

2013-01-01

Drillability indices, i.e., the Drilling Rate Index™ (DRI), Bit Wear Index™ (BWI), Cutter Life Index™ (CLI), and Vickers Hardness Number Rock (VHNR), are indirect measures of rock drillability. These indices are recognized as providing practical characterization of rock properties used in the Norwegian University of Science and Technology (NTNU) time and cost prediction models available for hard rock tunneling and surface excavation. The tests form the foundation of various hard rock equipment capacity and performance prediction methods. In this paper, application of the tests for tunnel boring machine (TBM) and drill and blast (D&B) tunneling is investigated and the impact of the indices on excavation time and costs is presented.

Effect of Crystallisation Degree on Hardness of Basaltic Glass-Ceramics

DEFF Research Database (Denmark)

Jensen, Martin; Smedskjær, Morten Mattrup; Yue, Yuanzheng

The dependence of hardness of basaltic glass-ceramics on their crystallisation degree has been explored by means of differential scanning calorimetry, optical microscopy, X-ray diffraction, and Vickers indentation. Different degrees of crystallisation in the basaltic glasses have been obtained...... by varying the temperature of heat treatment. The change of the relative degree of crystallisation with the heat treatment temperature can be described by an empirical model established in this work. The predominant crystalline phase in the glass has been identified as the pyroxene augite. The hardness...... principle calculations. It is found that the hardness of the glass phase decreases slightly with an increase in the degree of crystallisation, while that of the augite phase drastically decreases....

Hardness and microstructural characteristics of rapidly solidified Al-8-16 wt.%Si alloys

International Nuclear Information System (INIS)

Uzun, O.; Karaaslan, T.; Gogebakan, M.; Keskin, M.

2004-01-01

Al-Si alloys with nominal composition of Al-8 wt.%Si, Al-12 wt.%Si, and Al-16 wt.%Si were rapidly solidified by using melt-spinning technique to examine the influence of the cooling rate/conditions on microstructure and mechanical properties. The microstructures of the rapidly solidified ribbons and ingot samples were investigated by the optical microscopy, electron microscopy and X-ray diffraction (XRD) techniques. The results showed that the structures of all melt-spun ribbons were completely composed of finely dispersed α-Al and eutectic Si phase, and primary silicon was not observed. The XRD analysis indicated that the solubility of Si in the α-Al matrix was greatly increased with rapid solidification. Additionally, mechanical properties of both conventionally cast (ingot) and melt-spun ribbons were examined by using Vickers indenter for one applied load (0.098 N). The hardness values of the melt-spun ribbons were about three times higher than those of ingot counterparts. The high hardness of the rapidly solidified state can be attributed to the supersaturated solid solutions. Besides, hardness values with different applied loads were measured for melt-spun ribbons. The results indicated that Vickers hardness values (H v ) of the ribbons depended on the applied load. Applying the concept of Hays-Kendall, the load independent hardness values were calculated as 694.0, 982.8 and 1186.8 MN/m 2 for Al-8 wt.%Si, Al-12 wt.%Si and Al-16 wt.%Si, respectively

Correlation between some thermo-mechanical and physico-chemical properties in multi-component glasses of Se-Te-Sn-Cd system

Science.gov (United States)

Kumar, Amit; Mehta, Neeraj

2017-06-01

The glass transition phenomenon is guided by the swift cooling of a melt (glass-forming liquid). Consequently, the glass as a final product consists of a considerable number of micro-voids having the size of the order of atomic and/or molecular sizes. The model of free volume fluctuation helps in describing the diverse physico-chemical properties of amorphous materials (like glasses and polymers). This theory is based on the fraction of fluctuation free frozen at the glass transition temperature and it forms a basis for determination of various significant thermo-mechanical properties. In the present work, Vickers hardness test method is employed that provides useful information concerning the mechanical behavior of brittle solids. The present work emphasizes the results of micro-indentation measurements on recently synthesized novel Se78- x Te20Sn2Cd x glassy system. Basic thermo-mechanical parameters such as micro-hardness, volume ( V h), formation energy ( E h) of micro-voids in the glassy network and modulus of elasticity ( E) have been determined and their variation with glass composition has been investigated.

Correlation between some thermo-mechanical and physico-chemical properties in multi-component glasses of Se-Te-Sn-Cd system

International Nuclear Information System (INIS)

Kumar, Amit; Mehta, Neeraj

2017-01-01

The glass transition phenomenon is guided by the swift cooling of a melt (glass-forming liquid). Consequently, the glass as a final product consists of a considerable number of micro-voids having the size of the order of atomic and/or molecular sizes. The model of free volume fluctuation helps in describing the diverse physico-chemical properties of amorphous materials (like glasses and polymers). This theory is based on the fraction of fluctuation free frozen at the glass transition temperature and it forms a basis for determination of various significant thermo-mechanical properties. In the present work, Vickers hardness test method is employed that provides useful information concerning the mechanical behavior of brittle solids. The present work emphasizes the results of micro-indentation measurements on recently synthesized novel Se_7_8_-_xTe_2_0Sn_2Cd_x glassy system. Basic thermo-mechanical parameters such as micro-hardness, volume (V_h), formation energy (E_h) of micro-voids in the glassy network and modulus of elasticity (E) have been determined and their variation with glass composition has been investigated. (orig.)

Room temperature Young's modulus, shear modulus, Poisson's ratio and hardness of PbTe-PbS thermoelectric materials

Energy Technology Data Exchange (ETDEWEB)

Ni, Jennifer E [Chemical Engineering and Materials Science Department, Michigan State University, East Lansing, MI 48824 (United States); Case, Eldon D., E-mail: casee@egr.msu.edu [Chemical Engineering and Materials Science Department, Michigan State University, East Lansing, MI 48824 (United States); Khabir, Kristen N; Stewart, Ryan C [Chemical Engineering and Materials Science Department, Michigan State University, East Lansing, MI 48824 (United States); Wu, Chun-I; Hogan, Timothy P [Electrical and Computer Engineering Department, Michigan State University, East Lansing, MI 48824 (United States); Timm, Edward J [Mechanical Engineering Department, Michigan State University, East Lansing, MI 48824 (United States); Girard, Steven N; Kanatzidis, Mercouri G [Department of Chemistry, Northwestern University, Evanston, IL (United States)

2010-06-15

Two-phase PbTe-PbS materials, in which PbS is a nanostructured phase, are promising thermoelectric materials for the direct conversion of heat energy into electricity. In this study, a Vickers indentation mean hardness of 1.18 {+-} 0.09 GPa was measured for hot pressed specimens Pb{sub 0.95}Sn{sub 0.05}Te-PbS 8% while the mean hardness of cast specimens was 0.68 {+-} 0.07 GPa. The mean fracture toughness of the not pressed specimens was estimated as 0.35 {+-} 0.04 MPa m{sup 1/2} via Vickers indentation. Resonant Ultrasound Spectroscopy (RUS) measurements on hot pressed specimens gave mean values of Young's modulus, shear modulus and Poisson's ratio of 53.1 GPa, 21.4 GPa and 0.245, respectively while for the cast specimens the Young's and shear moduli were about 10% lower than for the hot pressed, with a mean value of Poisson's ratio of 0.245. The differences between the hardness and elastic moduli values for the cast and hot pressed specimens are discussed.

The hardness of synthetic products obtained from cooled and crystallized basaltic melts (in Romanian

Directory of Open Access Journals (Sweden)

Daniela Ogrean

2001-04-01

Full Text Available The Hardness of Synthetic Products Obtained from Cooled and Crystallized Basaltic Melts. Hardness is one of the main properties of the products obtained from cooled and crystallized basaltic melts under a controlled thermal regime. It influences the abrasion tear resistance of the resulted material. The microhardness measurements on the samples (bricks, boards, gutters, armour plates, tubes indicated Vickers hardness value between 757–926 for the materials obtained from Şanovita basalts (Timiş district and between 539–958 respectively, in case of the Racoş basalts (Braşov district. There is a certain variation of the hardness within the same sample, in various measurement points, within the theoretical limits of the hardnesses of the pyroxenes and that of the spinels.

Growth and characterization of β-Ga2O3 crystals

Science.gov (United States)

Nikolaev, V. I.; Maslov, V.; Stepanov, S. I.; Pechnikov, A. I.; Krymov, V.; Nikitina, I. P.; Guzilova, L. I.; Bougrov, V. E.; Romanov, A. E.

2017-01-01

Here we report on the growth and characterization of β-Ga2O3 bulk crystals and polycrystalline layer on different substrates. Bulk β-Ga2O3 crystals were produced by free crystallisation of gallium oxide melt in sapphire crucible. Transparent single crystals measuring up to 8 mm across were obtained. Good structural quality was confirmed by x-ray diffraction rocking curve FWHM values of 46″. Young's modulus, shear modulus and hardness of the β-Ga2O3 crystals were measured by nanoindentation and Vickers microindentation techniques. Polycrystalline β-Ga2O3 films were deposited on silicon and sapphire substrates by sublimation method. It was found that structure and morphology of the films were greatly influenced by the material and orientation of the substrates. The best results were achieved on a-plane sapphire substrates where predominantly (111) oriented films were obtained.

Microstructure of directionally solidified Ti-Fe eutectic alloy with low interstitial and high mechanical strength

Science.gov (United States)

Contieri, R. J.; Lopes, E. S. N.; Taquire de La Cruz, M.; Costa, A. M.; Afonso, C. R. M.; Caram, R.

2011-10-01

The performance of Ti alloys can be considerably enhanced by combining Ti and other elements, causing an eutectic transformation and thereby producing composites in situ from the liquid phase. This paper reports on the processing and characterization of a directionally solidified Ti-Fe eutectic alloy. Directional solidification at different growth rates was carried out in a setup that employs a water-cooled copper crucible combined with a voltaic electric arc moving through the sample. The results obtained show that a regular fiber-like eutectic structure was produced and the interphase spacing was found to be a function of the growth rate. Mechanical properties were measured using compression, microindentation and nanoindentation tests to determine the Vickers hardness, compressive strength and elastic modulus. Directionally solidified eutectic samples presented high values of compressive strength in the range of 1844-3000 MPa and ductility between 21.6 and 25.2%.

Effect of Dental Restorative Material Type and Shade on Characteristics of Two-Layer Dental Composite Systems

Directory of Open Access Journals (Sweden)

Atefeh Karimzadeh

Full Text Available Abstract The purpose of this study was to investigate the effects of shade and material type and shape in dental polymer composites on the hardness and shrinkage stress of bulk and two-layered restoration systems. For this purpose, some bulk and layered specimens from three different shades of dental materials were prepared and light-cured. The experiments were carried out on three types of materials: conventional restorative composite, nanohybrid composite and nanocomposite. Micro-indentation experiment was performed on the bulk and also on each layer of layered restoration specimens using a Vicker's indenter. The interface between the two layers was studied by scanning electron microscopy (SEM. The results revealed significant differences between the values of hardness for different shades in the conventional composite and also in the nanohybrid composite. However, no statistically significant difference was observed between the hardness values for different shades in the nanocomposite samples. The layered restoration specimens of different restorative materials exhibited lower hardness values with respect to their bulk specimens. The reduction in the hardness value of the layered conventional composite samples was higher than those of the nanocomposite and nanohybrid composite specimens indicating more shrinkage stresses generated in the conventional composite restorations. According to the SEM images, a gap was observed between the two layers in the layered restorations.

Microindentation Hardness-Secondary Dendritic Spacings Correlation with Casting Thermal Parameters in an Al-9wt.%Si Alloy

Directory of Open Access Journals (Sweden)

Diego CARVALHO

2018-02-01

Full Text Available Experiments were carried out to analyze the effect of growth rates (VL and cooling rates (TR on both secondary dendritic arm spacings (λ2 and Vickers microhardness (HV of an Al-9wt.%Si alloy during the horizontal directional solidification under transient heat flow conditions. A water-cooled solidification experimental apparatus was developed allowing a wide range of TR (from 0.2 to 3.5 ºC/s to be experienced. Five computer guided thermocouples were connected with the metal, and the time-temperature data were recorded automatically. The solidification path was also calculated by Scheil model in Thermo-Calc software. Casting samples were characterized by the combined analyses of optical microscopy (OM and scanning electron microscopy coupled with energy dispersive spectrometry (SEM-EDS revealing a complex arrangement of phases including binary (α-Al + Si and ternary (α-Al + Si + β-AlFeSi mixtures within interdendritic regions. It was observed that power law functions characterize the variation of λ2 as a function of VL and TR with exponents of -2/3 and -1/3, respectively. Finally, experimental laws of power and Hall-Petch types are proposed relating the resulting HV to the λ2. According to these results, it was found that, for increasing values of λ2, the results of HV decrease.DOI: http://dx.doi.org/10.5755/j01.ms.24.1.17319

Effect of sintering atmosphere on the hardness of ThO2

Science.gov (United States)

Baena, Angela; Cardinaels, Thomas; Van Eyken, Jelle; Puzzolante, Jean Louis; Binnemans, Koen; Verwerft, Marc

2016-08-01

The hardness and toughness of ThO2 sintered under reducing and oxidizing conditions has been investigated and, quite unexpectedly, a significant difference in hardness was observed for the entire range of porosities studied. Reducing conditions systematically yielded higher hardness values than oxidizing conditions. Extrapolated to zero porosity, the hardness for ThO2 is H0 = 10.5 ± 0.3 GPa for oxidizing conditions and H0 = 12.4 ± 0.7 GPa for reducing conditions. Toughness values have been derived from Vickers indentations; differences in toughness were insignificant and only a single value is proposed: KIC = 0.97 ± 0.12 MPa √m. The difference in hardness is attributed to the presence of point defects, also acting as color centers and causing grey coloration of ThO2 sintered under reducing conditions. Furthermore, and of interest for nuclear fuel production, is the finding that ThO2 sintered under reducing conditions is significantly easier to grind compared to material sintered under oxidizing conditions.

Influence of temperature, grain size and cobalt content on the hardness of WC-Co alloys

CSIR Research Space (South Africa)

Milman, YV

1999-01-01

Full Text Available temperatures: ?196, ?80, 20, 200, 300, 400, 500, 600, 700, 800 and 900?C. In the range 20?900?C the hardness is measured using a 60 N load in a BIM-1 installation [2] in a vacuum of about 10?3 Pa. In this installation the load on the Vickers indenter...

Production and mechanical properties of sintered carbides (hard steels WC-Co)

International Nuclear Information System (INIS)

Batalha, G.F.

1987-09-01

Densification and mechanical characteristics or WC-Co Cemented Carbides, were investigated by dilatometry, Hardness and bending tests, as a function of the two principal micro-structural parameters: the cobalt content and the particle size of carbide crystals. Vickers hardness of the studied compositions showed a linear variation with the increase of the cobalt content. By three point bending, the transverse rupture strenght increases with cobalt content, however, for larger grain size reaches a maximum, eventually reduced by brittle phases and incomplete dispersion. The results of brittle facture tests were statistically analised and fitted better to the 'Weakest Link Model' (Weibull distribution) than the 'Chain Model' (Gaussian distribution). (author) [pt

Theoretical Conversions of Different Hardness and Tensile Strength for Ductile Materials Based on Stress-Strain Curves

Science.gov (United States)

Chen, Hui; Cai, Li-Xun

2018-04-01

Based on the power-law stress-strain relation and equivalent energy principle, theoretical equations for converting between Brinell hardness (HB), Rockwell hardness (HR), and Vickers hardness (HV) were established. Combining the pre-existing relation between the tensile strength ( σ b ) and Hollomon parameters ( K, N), theoretical conversions between hardness (HB/HR/HV) and tensile strength ( σ b ) were obtained as well. In addition, to confirm the pre-existing σ b -( K, N) relation, a large number of uniaxial tensile tests were conducted in various ductile materials. Finally, to verify the theoretical conversions, plenty of statistical data listed in ASTM and ISO standards were adopted to test the robustness of the converting equations with various hardness and tensile strength. The results show that both hardness conversions and hardness-strength conversions calculated from the theoretical equations accord well with the standard data.

Surface enrichment with chrome and nitriding of IF steel under an abnormal glow discharge; Enriquecimento superficial com cromo e nitretacao do aco IF em descarga eletrica em regime anormal

Energy Technology Data Exchange (ETDEWEB)

Meira, S.R.; Borges, P.C., E-mail: sabrina.r.meira@gmail.com [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil). Grupo de Materiais; Bernardelli, E.A. [Instituto Federal do Parana (IFPR), Paranagua, PR (Brazil). Laboratorio de Materiais

2014-07-01

The objective of this work is to evaluate the influence of surface enrichment of IF steel with chrome, and nitriding, the formation of the nitrided layer. Thus, IF steel samples were subjected to surface enrichment process, using 409 stainless steel as a target for sputtering, followed by plasma nitriding, both under a dc abnormal glow discharge. The enrichment treatment was operated at 1200 ° C for 3h. The nitriding treatment was operated at 510 ° C for 2 h. The influence of the treatments on the layers formed was studied through optical microscopy (OM), scan electron microscopy (SEM), X-ray diffraction (XRD) and Vickers microindentation. The results show that the enrichment is effective to enrich the IF surface, furthermore, improves the characteristics of nitriding, comparing nitriding samples to nitriding and enriched, was observed needles of nitrides, as well as a higher hardness, which is associated with the nitrides of chrome, on the nitriding and enriched samples. (author)

Surface enrichment with chrome and nitriding of IF steel under an abnormal glow discharge

International Nuclear Information System (INIS)

Meira, S.R.; Borges, P.C.; Bernardelli, E.A.

2014-01-01

The objective of this work is to evaluate the influence of surface enrichment of IF steel with chrome, and nitriding, the formation of the nitrided layer. Thus, IF steel samples were subjected to surface enrichment process, using 409 stainless steel as a target for sputtering, followed by plasma nitriding, both under a dc abnormal glow discharge. The enrichment treatment was operated at 1200 ° C for 3h. The nitriding treatment was operated at 510 ° C for 2 h. The influence of the treatments on the layers formed was studied through optical microscopy (OM), scan electron microscopy (SEM), X-ray diffraction (XRD) and Vickers microindentation. The results show that the enrichment is effective to enrich the IF surface, furthermore, improves the characteristics of nitriding, comparing nitriding samples to nitriding and enriched, was observed needles of nitrides, as well as a higher hardness, which is associated with the nitrides of chrome, on the nitriding and enriched samples. (author)

Correlation between some thermo-mechanical and physico-chemical properties in multi-component glasses of Se-Te-Sn-Cd system

Energy Technology Data Exchange (ETDEWEB)

Kumar, Amit; Mehta, Neeraj [Banaras Hindu University, Department of Physics, Institute of Science, Varanasi (India)

2017-06-15

The glass transition phenomenon is guided by the swift cooling of a melt (glass-forming liquid). Consequently, the glass as a final product consists of a considerable number of micro-voids having the size of the order of atomic and/or molecular sizes. The model of free volume fluctuation helps in describing the diverse physico-chemical properties of amorphous materials (like glasses and polymers). This theory is based on the fraction of fluctuation free frozen at the glass transition temperature and it forms a basis for determination of various significant thermo-mechanical properties. In the present work, Vickers hardness test method is employed that provides useful information concerning the mechanical behavior of brittle solids. The present work emphasizes the results of micro-indentation measurements on recently synthesized novel Se{sub 78-x}Te{sub 20}Sn{sub 2}Cd{sub x} glassy system. Basic thermo-mechanical parameters such as micro-hardness, volume (V{sub h}), formation energy (E{sub h}) of micro-voids in the glassy network and modulus of elasticity (E) have been determined and their variation with glass composition has been investigated. (orig.)

Effect of pulsed laser parameters on in-situ TiC synthesis in laser surface treatment

Science.gov (United States)

Hamedi, M. J.; Torkamany, M. J.; Sabbaghzadeh, J.

2011-04-01

Commercial titanium sheets pre-coated with 300-μm thick graphite layer were treated by employing a pulsed Nd:YAG laser in order to enhance surface properties such as wear and erosion resistance. Laser in-situ alloying method produced a composite layer by melting the titanium substrate and dissolution of graphite in the melt pool. Correlations between pulsed laser parameters, microstructure and microhardness of the synthesized composite coatings were investigated. Effects of pulse duration and overlapping factor on the microstructure and hardness of the alloyed layer were deduced from Vickers micro-indentation tests, XRD, SEM and metallographic analyses of cross sections of the generated layer. Results show that the composite cladding layer was constituted with TiC intermetallic phase between the titanium matrix in particle and dendrite forms. The dendritic morphology of composite layer was changed to cellular grain structure by increasing laser pulse duration and irradiated energy. High values of the measured hardness indicate that deposited titanium carbide increases in the conditions with more pulse duration and low process speed. This occurs due to more dissolution of carbon into liquid Ti by heat input increasing and positive influence of the Marangoni flow in the melted zone.

Effect of milling time on the structure, micro-hardness, and thermal behavior of amorphous/nanocrystalline TiNiCu shape memory alloys developed by mechanical alloying

International Nuclear Information System (INIS)

Alijani, Fatemeh; Amini, Rasool; Ghaffari, Mohammad; Alizadeh, Morteza; Okyay, Ali Kemal

2014-01-01

Highlights: • Potential to produce B1′ (thermal- and stress-induced) and B2 was established. • Martensitic transformation occurred without the formation of intermediate R-phase. • Formation of unwanted intermetallics during heating was hindered by milling. • During milling, microhardness was increased, then reduced, and afterward re-increased. • By milling evolution, thermal crystallization steps changed from 3 to 2. - Abstract: In the present paper, the effect of milling process on the chemical composition, structure, microhardness, and thermal behavior of Ti–41Ni–9Cu compounds developed by mechanical alloying was evaluated. The structural characteristic of the alloyed powders was evaluated by X-ray diffraction (XRD). The chemical composition homogeneity and the powder morphology and size were studied by scanning electron microscopy coupled with electron dispersive X-ray spectroscopy. Moreover, the Vickers micro-indentation hardness of the powders milled for different milling times was determined. Finally, the thermal behavior of the as-milled powders was studied by differential scanning calorimetery. According to the results, at the initial stages of milling (typically 0–12 h), the structure consisted of a Ni solid solution and amorphous phase, and by the milling evolution, nanocrystalline martensite (B19′) and austenite (B2) phases were initially formed from the initial materials and then from the amorphous phase. It was found that by the milling development, the composition uniformity is increased, the inter-layer thickness is reduced, and the powders microhardness is initially increased, then reduced, and afterward re-increased. It was also realized that the thermal behavior of the alloyed powders and the structure of heat treated samples is considerably affected by the milling time

Finite element analysis of stresses in Berkovich, Vickers and Knoop indentation for densifying and non-densifying glasses

Science.gov (United States)

Chen, Kanghua

2002-08-01

during a material removal experiment of magnetorheological finishing (MRF) of fused silica. The explanation of indentation size effect (ISE) is attempted using numerical indentation simulations. Vickers indentation simulations on the five selected brittle materials (FS, BK7, Si, LHG8 and CaF2.) show no size dependence of Vickers hardness when the material is modeled as elastic-perfectly plastic (with or without densification). The simulation results on axisymmetric conical indentation also indicate that the bluntness of the indenter tip is not the reason for the indentation size effect. A new constitutive model accounting for the material length scale is needed in order to explain the well-observed indentation size effect during indentation tests.

Residual stresses around Vickers indents

International Nuclear Information System (INIS)

Pajares, A.; Guiberteau, F.; Steinbrech, R.W.

1995-01-01

The residual stresses generated by Vickers indentation in brittle materials and their changes due to annealing and surface removal were studied in 4 mol% yttria partially stabilized zirconia (4Y-PSZ). Three experimental methods to gain information about the residual stress field were applied: (i) crack profile measurements based on serial sectioning, (ii) controlled crack propagation in post indentation bending tests and (iii) double indentation tests with smaller secondary indents located around a larger primary impression. Three zones of different residual stress behavior are deduced from the experiments. Beneath the impression a crack free spherical zone of high hydrostatic stresses exists. This core zone is followed by a transition regime where indentation cracks develop but still experience hydrostatic stresses. Finally, in an outward third zone, the crack contour is entirely governed by the tensile residual stress intensity (elastically deformed region). Annealing and surface removal reduce this crack driving stress intensity. The specific changes of the residual stresses due to the post indentation treatments are described and discussed in detail for the three zones

The Effect of Diode Laser Treatment for Root Canal Disinfection on Fracture Resistance and Micro-hardness of the Tooth

International Nuclear Information System (INIS)

Elmiligy, H.H; Diab, A.H.; Sabet, N.E.; Saafan, A.M.

2014-01-01

This study evaluated the effect of diode laser treatment for root canal disinfection on fracture resistance and micro-hardness of the tooth. Sixty freshly extracted mandibular and maxillary premolars were accessed under coolant then root canals were flared up to apical preparation size 40 MFA coupled with 5.25% NaOCl as an irrigant. Teeth were divided into two groups, control group (group I) and lased group (group II) that was lased by diode laser with average power 2 w through fibrooptic into the canal 2 mm shorter than the apex. Each tooth was embedded in acrylic block, and then subjected to the fracture resistance test. Each root was then sectioned transversely and polished to record dentin Vickers hardness. Data was analysed with student t-test then with linear regression test. The Lased samples presented a significantly higher resistance to fracture than unlased samples. There was no statistically significant differences found between Vickers hardness (HV) of lased and unlased samples and there was no relation between fracture resistance and microhardness. Diode laser (980 nm) treatment had no adverse effect on dentin microhardness, also it increased the fracture resistance of dentin. Diode laser (980 nm) treatment could attain better function ability and maintenance of tooth after endodontic treatment.

Quality assurance in design: policy adopted by Vickers Barrow Engineering Works

International Nuclear Information System (INIS)

Aubrey, J.H.

1976-01-01

The quality assurance system operated by the Vickers Barrow Engineering Works is described, with special reference to the design of the reactor shield and above core structure for the first commercial fast reactor. Section headings are: introduction; what is quality assurance of design; attitude of designer; design discipline; customers attitude; Engineering Company system; future application of Design Quality Assurance Record system. (U.K.)

U3Si2 Fabrication and Testing for Implementation into the BISON Fuel Performance Code

Energy Technology Data Exchange (ETDEWEB)

Knight, Travis W.

2018-04-23

A creep test stand was designed and constructed for compressive creep testing of U3Si2 pellets. This is described in Chapter 3.

• Creep testing of U3Si2 pellets was completed. In total, 13 compressive creep tests of U3Si2 pellets was successfully completed. This is reported in Chapter 3.
• Secondary creep model of U3Si2 was developed and implemented in BISON. This is described in Chapter 4.
• Properties of U3Si2 were implemented in BISON. This is described in Chapter 4.
• A resonant frequency and damping analyzer (RFDA) using impulse excitation technique (IET) was setup, tested, and used to analyze U3Si2 samples to measure Young’s and Shear Moduli which were then used to calculate the Poisson ratio for U3Si2. This is described in Chapter 5.
• Characterization of U3Si2 samples was completed. Samples were prepared and analyzed by XRD, SEM, and optical microscopy. Grain size analysis was conducted on images.

Estimation of the Ultimate Tensile Strength of Steel from Its HB and HV Hardness Numbers and Coercive Force

Science.gov (United States)

Sandomirskii, S. G.

2017-11-01

A formula is derived to accurately describe the tabulated relation between the Brinell ( HB) and Vickers ( HV) hardnesses of steel over the entire range of their possible variation. This formula and the formulas describing the relation between the HB hardness of chromium-molybdenum and chromium-nickel steels and their ultimate tensile strength σu are used to analyze the change in σu of 38KhNM steel upon quenching and tempering. The data that reveal a relation between σu of 38KhNM steel and its coercive force are obtained.

Effect of heat-treatment on the hardness and mechanical properties of Boron Alloyed Steel

Directory of Open Access Journals (Sweden)

bin Khiyon Mohammad Raffik

2017-01-01

Full Text Available In an automotive industry, hot stamped, die quenched structural components have been widely used to provide extra protection against crash intrusion. Boron alloyed steel exhibit limited ductility, but it also promotes improvement in impact performance. This study analyzed the effect of cooling rate on the hardness and energy absorption. Self-quenched specimens were heated to 850°C and cooled in air of room temperature, water at room temperature and cold water. Vickers hardness test and tensile test was then carried out to analyze the effect of different quenching rate. Self-quenched specimens were compared to the properties of the die-quenched specimens obtained from commercial automobile body. Result shows that boron steel with the highest cooling rate has the highest value of hardness but low in strength.

Cartilage microindentation using cylindrical and spherical optical fiber indenters with integrated Bragg gratings as force sensors

Science.gov (United States)

Marchi, G.; Canti, O.; Baier, V.; Micallef, W.; Hartmann, B.; Alberton, P.; Aszodi, A.; Clausen-Schaumann, H.; Roths, J.

2018-02-01

Fiber optic microindentation sensors that have the potential to be integrated into arthroscopic instruments and to allow localizing degraded articular cartilage are presented in this paper. The indenters consist of optical fibers with integrated Bragg gratings as force sensors. In a basic configuration, the tip of the fiber optic indenter consists of a cleaved fiber end, forming a cylindrical flat punch indenter geometry. When using this indenter geometry, high stresses at the edges of the cylinder are present, which can disrupt the tissue structure. This is avoided with an improved version of the indenter. A spherical indenter tip that is formed by melting the end of the glass fiber. The spherical fiber tip shows the additional advantage of strongly reducing reflections from the fiber end. This allows a reduction of the length of the fiber optic sensor element from 65 mm of the flat punch type to 27 mm of the spherical punch. In order to compare the performance of both indenter types, in vitro stress-relaxation indentation experiments were performed on bovine articular cartilage with both indenter types, to assess biomechanical properties of bovine articular cartilage. For indentation depths between 60 μm and 300 μm, the measurements with both indenter types agreed very well with each other. This shows that both indenter geometries are suitable for microindentation measuremnts . The spherical indenter however has the additional advantage that it minimizes the risk to damage the surface of the tissue and has less than half dimensions than the flat indenter.

In Vitro Comparative Study of Two Different Bleaching Agents on Micro-hardness Dental Enamel.

Science.gov (United States)

Fatima, Nazish; Ali Abidi, Syed Yawar; Meo, Ashraf Ali

2016-02-01

To evaluate the effect of home-use bleaching agent containing 16% Carbamide Peroxide (CP) and in-office bleaching agent containing 38% Hydrogen Peroxide (HP) on enamel micro-hardness. An in vitroexperimental study. Department of Operative Dentistry and Science of Dental Materials at Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences and Material Engineering Department of NED University of Engineering and Technology, Karachi, from July to December 2014. Atotal of 90 enamel slabs from 45 sound human 3rd molar were randomly divided into 3 groups. Each group contained 30 specimens (n=30). Group 1 was kept in artificial saliva at 37°C in incubator during the whole experiment. However, Groups 2 and 3 were treated with power whitening gel and tooth whitening pen respectively. After bleaching session, specimens were thoroughly rinsed with deionized water again for 10 seconds and then stored in artificial saliva at 37°C in incubator. Artificial saliva was changed after every 2 days. The Vickers hardness tester (Wolpert 402 MVD, Germany) was adjusted to a load of 0.1 kg (100 gm) and dwell time of 5 seconds. Three Vickers were performed on each specimen using a hardness tester according to the ISO 6507-3:1998 specification. Micro-hardness measurements were performed before and after bleaching at day 1, 7 and 14. In the control group, the baseline micro-hardness was 181.1 ±9.3 which was reduced after the storage on day 1, 7 and 14 (p = 0.104). In Group 2, baseline micro-hardness was 180.4 ±10.1 which was reduced to 179.79 ±10.0 units after day 1. Whereas, on day 7 and 14, the values of micro-hardness were 179.8 ±10 and 179.7 ±10.29, respectively (p=0.091). Furthermore, the baseline micro-hardness in Group 3 was 174.0 ±22.9 units which was reduced to 173 ±23 on day 1, 170 ±30 on day 7 and 173 ±23 on day 14 (p = 0.256). The statistically insignificant difference was found among micro-hardness values of different bleaching

In Vitro Comparative Study of Two Different Bleaching Agents on Micro-hardness Dental Enamel

International Nuclear Information System (INIS)

Fatima, N.; Abidi, S. Y. A.; Meo, A. A.

2016-01-01

Objective: To evaluate the effect of home-use bleaching agent containing 16 percentage Carbamide Peroxide (CP) and in-office bleaching agent containing 38 percentage Hydrogen Peroxide (HP) on enamel micro-hardness. Study Design: An in vitro experimental study. Place and Duration of Study: Department of Operative Dentistry and Science of Dental Materials at Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences and Material Engineering Department of NED University of Engineering and Technology, Karachi, from July to December 2014. Methodology: A total of 90 enamel slabs from 45 sound human 3rd molar were randomly divided into 3 groups. Each group contained 30 specimens (n=30). Group 1 was kept in artificial saliva at 37 Degree C in incubator during the whole experiment. However, Groups 2 and 3 were treated with power whitening gel and tooth whitening pen respectively. After bleaching session, specimens were thoroughly rinsed with deionized water again for 10 seconds and then stored in artificial saliva at 37 Degree C in incubator. Artificial saliva was changed after every 2 days. The Vickers hardness tester (Wolpert 402 MVD, Germany) was adjusted to a load of 0.1 kg (100 gm) and dwell time of 5 seconds. Three Vickers were performed on each specimen using a hardness tester according to the ISO 6507-3:1998 specification. Micro-hardness measurements were performed before and after bleaching at day 1, 7 and 14. Results: In the control group, the baseline micro-hardness was 181.1 ± 9.3 which was reduced after the storage on day 1, 7 and 14 (p = 0.104). In Group 2, baseline micro-hardness was 180.4 ±10.1 which was reduced to 179.79 ± 10.0 units after day 1. Whereas, on day 7 and 14, the values of micro-hardness were 179.8 ±10 and 179.7 ±10.29, respectively (p=0.091). Furthermore, the baseline micro-hardness in Group 3 was 174.0 ±22.9 units which was reduced to 173 ± 23 on day 1, 170 ±30 on day 7 and 173 ± 23 on day 14 (p = 0

Assessment of the hardness of different orthodontic wires and brackets produced by metal injection molding and conventional methods.

Science.gov (United States)

Alavi, Shiva; Kachuie, Marzie

2017-01-01

This study was conducted to assess the hardness of orthodontic brackets produced by metal injection molding (MIM) and conventional methods and different orthodontic wires (stainless steel, nickel-titanium [Ni-Ti], and beta-titanium alloys) for better clinical results. A total of 15 specimens from each brand of orthodontic brackets and wires were examined. The brackets (Elite Opti-Mim which is produced by MIM process and Ultratrimm which is produced by conventional brazing method) and the wires (stainless steel, Ni-Ti, and beta-titanium) were embedded in epoxy resin, followed by grinding, polishing, and coating. Then, X-ray energy dispersive spectroscopy (EDS) microanalysis was applied to assess their elemental composition. The same specimen surfaces were repolished and used for Vickers microhardness assessment. Hardness was statistically analyzed with Kruskal-Wallis test, followed by Mann-Whitney test at the 0.05 level of significance. The X-ray EDS analysis revealed different ferrous or co-based alloys in each bracket. The maximum mean hardness values of the wires were achieved for stainless steel (SS) (529.85 Vickers hardness [VHN]) versus the minimum values for beta-titanium (334.65 VHN). Among the brackets, Elite Opti-Mim exhibited significantly higher VHN values (262.66 VHN) compared to Ultratrimm (206.59 VHN). VHN values of wire alloys were significantly higher than those of the brackets. MIM orthodontic brackets exhibited hardness values much lower than those of SS orthodontic archwires and were more compatible with NiTi and beta-titanium archwires. A wide range of microhardness values has been reported for conventional orthodontic brackets and it should be considered that the manufacturing method might be only one of the factors affecting the mechanical properties of orthodontic brackets including hardness.

Effect of Substrate Bias on Friction Coefficient, Adhesion Strength and Hardness of TiN-COATED Tool Steel

Science.gov (United States)

Hamzah, Esah; Ali, Mubarak; Toff, Mohd Radzi Hj. Mohd

In the present study, TiN coatings have been deposited on D2 tool steel substrates by using cathodic arc physical vapor deposition technique. The objective of this research work is to determine the usefulness of TiN coatings in order to improve the micro-Vickers hardness and friction coefficient of TiN coating deposited on D2 tool steel, which is widely used in tooling applications. A Pin-on-Disc test was carried out to study the coefficient of friction versus sliding distance of TiN coating deposited at various substrate biases. The standard deviation parameter during tribo-test result showed that the coating deposited at substrate bias of -75 V was the most stable coating. A significant increase in micro-Vickers hardness was recorded, when substrate bias was reduced from -150 V to zero. Scratch tester was used to compare the critical loads for coatings deposited at different bias voltages and the adhesion achievable was demonstrated with relevance to the various modes, scratch macroscopic analysis, critical load, acoustic emission and penetration depth. A considerable improvement in TiN coatings was observed as a function of various substrate bias voltages.

Interface strength of SiC/SiC composites with and without helium implantation using micro-indentation test

International Nuclear Information System (INIS)

Saito, M.; Ohtsuka, S.

1998-01-01

Helium implantation effects on interface strength of SiC/SiC composite were studied using the micro-indentation fiber push-out method. Helium implantation was carried out with an accelerator at about 400 K. Total amount of implanted helium was approximately 10000 appm. Increase of the fiber push-in load was observed in as-implanted specimen. After post-implantation-annealing at 1673 K for 1 h, the change of the fiber push-in load by helium implantation was not observed. Effects of helium implantation on the interface are discussed. (orig.)

Effect of sintering atmosphere on the hardness of ThO_2

International Nuclear Information System (INIS)

Baena, Angela; Cardinaels, Thomas; Van Eyken, Jelle; Puzzolante, Jean Louis; Binnemans, Koen; Verwerft, Marc

2016-01-01

The hardness and toughness of ThO_2 sintered under reducing and oxidizing conditions has been investigated and, quite unexpectedly, a significant difference in hardness was observed for the entire range of porosities studied. Reducing conditions systematically yielded higher hardness values than oxidizing conditions. Extrapolated to zero porosity, the hardness for ThO_2 is H_0 = 10.5 ± 0.3 GPa for oxidizing conditions and H_0 = 12.4 ± 0.7 GPa for reducing conditions. Toughness values have been derived from Vickers indentations; differences in toughness were insignificant and only a single value is proposed: K_I_C = 0.97 ± 0.12 MPa √m. The difference in hardness is attributed to the presence of point defects, also acting as color centers and causing grey coloration of ThO_2 sintered under reducing conditions. Furthermore, and of interest for nuclear fuel production, is the finding that ThO_2 sintered under reducing conditions is significantly easier to grind compared to material sintered under oxidizing conditions. - Highlights: • Reducing sintering conditions increase the hardness of polycrystalline ThO_2. • Systematic series of hardness versus porosity of ThO_2 were obtained. • Reducing sintering conditions improve grinding of ThO_2.

Vickers Attenuator. Volume 3C(VA) - Technical appraisal. Consultants' 1983 report

Energy Technology Data Exchange (ETDEWEB)

1986-01-01

A report is given by a team of Consultants on the estimated cost of converting wave energy to electrical energy by a 2 GW array of Vickers Attenuator wave energy devices and delivering this to a sub-station on the west coast of Skye. Comparisons of the estimates made by the team developing the concept are presented and discrepancies discussed. A detailed engineering assessment is given.

Assessment of Bone Health in Patients With Type 1 Gaucher Disease Using Impact Microindentation.

Science.gov (United States)

Herrera, Sabina; Pérez-López, Jordi; Moltó-Abad, Marc; Güerri-Fernández, Roberto; Cabezudo, Elena; Novelli, Silvana; Esteve, Jordi; Hernández, Albert; Roig, Inmaculada; Solanich, Xavier; Prieto-Alhambra, Daniel; Nogués, Xavier; Díez-Pérez, Adolfo

2017-07-01

Gaucher disease (GD), one of the most common lysosomal disorders (a global population incidence of 1:50,000), is characterized by beta-glucocerebrosidase deficiency. Some studies have demonstrated bone infiltration in up to 80% of patients, even if asymptomatic. Bone disorder remains the main cause of morbidity in these patients, along with osteoporosis, avascular necrosis, and bone infarcts. Enzyme replacement therapy (ERT) has been shown to improve these symptoms. This cross-sectional study included patients with type 1 Gaucher disease (GD1) selected from the Catalan Study Group on GD. Clinical data were collected and a general laboratory workup was performed. Bone mineral density (BMD) was measured at the lumbar spine and hip using dual-energy X-ray absorptiometry (DXA). Patients with bone infarcts or any other focal lesion in the area of indentation visible on imaging were excluded. Bone Material Strength index (BMSi) was measured by bone impact microindentation using an Osteoprobe instrument. Analysis of covariance (ANCOVA) models were fitted to adjust for age, sex, weight, and height. Sixteen patients with GD1 and 29 age- and sex-matched controls were included. GD1 was associated with significantly lower BMSi (adjusted beta -9.30; 95% CI, -15.18 to -3.42; p = 0.004) and reduced lumbar BMD (adjusted beta -0.14; 95% CI, -0.22 to -0.06; p = 0.002) and total hip BMD (adjusted beta -0.09; 95% CI, -0.15 to -0.03; p = 0.006), compared to GD1-free controls. Chitotriosidase levels were negatively correlated with BMSi (linear R 2  = 51.6%, p = 0.004). Bone tissue mechanical characteristics were deteriorated in patients with GD1. BMSi was correlated with chitotriosidase, the marker of GD activity. Bone disorder requires special consideration in this group of patients, and microindentation could be an appropriate tool for assessing and managing their bone health. © 2017 American Society for Bone and Mineral Research. © 2017 American Society for Bone

Surface hardness of hybrid ionomer cement after immersion in antiseptic solution

Directory of Open Access Journals (Sweden)

Anita Yuliati

2006-06-01

Full Text Available Hybrid ionomer cement or resin modified glass ionomer cement is a developed form of conventional glass ionomer cement. This hybrid ionomer cement can be eroded if in direct contact with acid solution which will affect surface hardness. The aim of this study is to learn surface hardness of hybrid ionomer cement after immersion in methyl salicylate 0.06% (pH 3.6 and povidon iodine 1% (pH 2.9 solution. Sample of hybrid ionomer cement with 5 mm diameter and 3 mm thickness was immersed in sterile aquadest solution (control, methyl salicylate pH 3.6, povidon iodine pH 2.9 for 1 minute, 7 and 14 minutes. Surface hardness was measured with Micro Vickers Hardness Tester. The obtained data was analyzed statistically with ANOVA followed by LSD test. The result of hybrid ionomer cement after immersion in sterile aquadest, methyl salicylate 0.06% pH 3.6 and povidon iodine 1% pH 2.9 for one minute, showed no significant difference; while immersion for 7 and 14 minutes showed a significant difference. The conclusion states that hybrid ionomer cement after 14 minutes immersion in povidon iodine 1% pH 2.9 has the lowest surface hardness.

Comparison of time-dependent changes in the surface hardness of different composite resins

Science.gov (United States)

Ozcan, Suat; Yikilgan, Ihsan; Uctasli, Mine Betul; Bala, Oya; Kurklu, Zeliha Gonca Bek

2013-01-01

Objective: The aim of this study was to evaluate the change in surface hardness of silorane-based composite resin (Filtek Silorane) in time and compare the results with the surface hardness of two methacrylate-based resins (Filtek Supreme and Majesty Posterior). Materials and Methods: From each composite material, 18 wheel-shaped samples (5-mm diameter and 2-mm depth) were prepared. Top and bottom surface hardness of these samples was measured using a Vicker's hardness tester. The samples were then stored at 37°C and 100% humidity. After 24 h and 7, 30 and 90 days, the top and bottom surface hardness of the samples was measured. In each measurement, the rate between the hardness of the top and bottom surfaces were recorded as the hardness rate. Statistical analysis was performed by one-way analysis of variance, multiple comparisons by Tukey's test and binary comparisons by t-test with a significance level of P = 0.05. Results: The highest hardness values were obtained from each two surfaces of Majesty Posterior and the lowest from Filtek Silorane. Both the top and bottom surface hardness of the methacrylate based composite resins was high and there was a statistically significant difference between the top and bottom hardness values of only the silorane-based composite, Filtek Silorane (P composite resin Filtek Silorane showed adequate hardness ratio, the use of incremental technic during application is more important than methacrylate based composites. PMID:24966724

Characterisation of weldment hardness, impact energy and microstructure in API X65 steel

International Nuclear Information System (INIS)

Hashemi, S.H.; Mohammadyani, D.

2012-01-01

The variation of microstructure and mechanical properties in various sub-zones of double submerged arc welded line pipe steel of grade API X65 was investigated. Instrumented Charpy V-notch tests and Vickers hardness experiments were conducted on the fusion zone, base metal and heat affected zone of the weld joint in 14.3 mm thick, 1219 mm outside diameter spiral pipeline. The lowest impact energy and the highest hardness level (160J and 218 HV, respectively) were recorded in the fusion zone. The low energy and high hardness characteristics of the seam weld can be attributed to its cast microstructure and the presence of grain boundary phases (such as proeutectoid ferrite), confirmed by standard metallographic observation. Despite this, service requirements set by the API 5L industry code (minimum impact energy of 73J, maximum hard spots of 350 HV) were fulfilled by the tested steel. Highlights: ► Experimental study of API X65 steel microstructure. ► Analysis of the relationship between X65 steel microstructure and hardness. ► Analysis of the relationship between X65 steel microstructure and impact energy. ► Presentation of detailed technical information on DSA welding in spiral pipes.

Effect of sintering atmosphere on the hardness of ThO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Baena, Angela; Cardinaels, Thomas [Belgian Nuclear Research Centre (SCK-CEN), Institute for Nuclear Materials Science, Fuel Materials Group, Boeretang 200, B-2400, Mol (Belgium); KU Leuven, Department of Chemistry, Celestijnenlaan 200F, P.O. Box 2404, B-3001, Heverlee (Belgium); Van Eyken, Jelle; Puzzolante, Jean Louis [Belgian Nuclear Research Centre (SCK-CEN), Institute for Nuclear Materials Science, Fuel Materials Group, Boeretang 200, B-2400, Mol (Belgium); Binnemans, Koen [KU Leuven, Department of Chemistry, Celestijnenlaan 200F, P.O. Box 2404, B-3001, Heverlee (Belgium); Verwerft, Marc, E-mail: marc.verwerft@sckcen.be [Belgian Nuclear Research Centre (SCK-CEN), Institute for Nuclear Materials Science, Fuel Materials Group, Boeretang 200, B-2400, Mol (Belgium)

2016-08-15

The hardness and toughness of ThO{sub 2} sintered under reducing and oxidizing conditions has been investigated and, quite unexpectedly, a significant difference in hardness was observed for the entire range of porosities studied. Reducing conditions systematically yielded higher hardness values than oxidizing conditions. Extrapolated to zero porosity, the hardness for ThO{sub 2} is H{sub 0} = 10.5 ± 0.3 GPa for oxidizing conditions and H{sub 0} = 12.4 ± 0.7 GPa for reducing conditions. Toughness values have been derived from Vickers indentations; differences in toughness were insignificant and only a single value is proposed: K{sub IC} = 0.97 ± 0.12 MPa √m. The difference in hardness is attributed to the presence of point defects, also acting as color centers and causing grey coloration of ThO{sub 2} sintered under reducing conditions. Furthermore, and of interest for nuclear fuel production, is the finding that ThO{sub 2} sintered under reducing conditions is significantly easier to grind compared to material sintered under oxidizing conditions. - Highlights: • Reducing sintering conditions increase the hardness of polycrystalline ThO{sub 2}. • Systematic series of hardness versus porosity of ThO{sub 2} were obtained. • Reducing sintering conditions improve grinding of ThO{sub 2}.

Effect of Heating Time on Hardness Properties of Laser Clad Gray Cast Iron Surface

Science.gov (United States)

Norhafzan, B.; Aqida, S. N.; Mifthal, F.; Zulhishamuddin, A. R.; Ismail, I.

2018-03-01

This paper presents effect of heating time on cladded gray cast iron. In this study, the effect of heating time on cladded gray cast iron and melted gray cast iron were analysed. The gray cast iron sample were added with mixed Mo-Cr powder using laser cladding technique. The mixed Mo and Cr powder was pre-placed on gray cast iron surface. Modified layer were sectioned using diamond blade cutter and polish using SiC abrasive paper before heated. Sample was heated in furnace for 15, 30 and 45 minutes at 650 °C and cool down in room temperature. Metallographic study was conduct using inverted microscope while surface hardness properties were tested using Wilson hardness test with Vickers scale. Results for metallographic study showed graphite flakes within matrix of pearlite. The surface hardness for modified layer decreased when increased heating time process. These findings are significant to structure stability of laser cladded gray cast iron with different heating times.

Bone material strength index as measured by impact microindentation is altered in patients with acromegaly.

Science.gov (United States)

Malgo, F; Hamdy, N A T; Rabelink, T J; Kroon, H M; Claessen, K M J A; Pereira, A M; Biermasz, N R; Appelman-Dijkstra, N M

2017-03-01

Acromegaly is a rare disease caused by excess growth hormone (GH) production by the pituitary adenoma. The skeletal complications of GH and IGF-1 excess include increased bone turnover, increased cortical bone mass and deteriorated microarchitecture of trabecular bone, associated with a high risk of vertebral fractures in the presence of relatively normal bone mineral density (BMD). We aimed to evaluate tissue-level properties of bone using impact microindentation (IMI) in well-controlled patients with acromegaly aged ≥18 years compared to 44 controls from the outpatient clinic of the Centre for Bone Quality. In this cross-sectional study, bone material strength index (BMSi) was measured in 48 acromegaly patients and 44 controls with impact microindentation using the osteoprobe. Mean age of acromegaly patients (54% male) was 60.2 years (range 37.9-76.5), and 60.5 years (range 39.8-78.6) in controls (50% male). Patients with acromegaly and control patients had comparable BMI (28.2 kg/m 2  ± 4.7 vs 26.6 kg/m 2  ± 4.3, P = 0.087) and comparable BMD at the lumbar spine (1.04 g/cm 2  ± 0.21 vs 1.03 g/cm 2  ± 0.13, P = 0.850) and at the femoral neck (0.84 g/cm 2  ± 0.16 vs 0.80 g/cm 2  ± 0.09, P = 0.246). BMSi was significantly lower in acromegaly patients than that in controls (79.4 ± 0.7 vs 83.2 ± 0.7; P acromegaly after reversal of long-term exposure to pathologically high GH and IGF-1 levels. Our findings also suggest that methods other than DXA should be considered to evaluate bone fragility in patients with acromegaly. © 2017 European Society of Endocrinology.

Computer-assisted acoustic emission analysis in alternating current magnetization and hardness testing of reactor pressure vessel steels

International Nuclear Information System (INIS)

Blochwitz, M.; Kretzschmar, F.; Rattke, R.

1985-01-01

Non-destructive determination of material characteristics such as nilductility transition temperature is of high importance in component monitoring during long-term operation. An attempt has been made to obtain characteristics correlating with mechanico-technological material characteristics by both acoustic resonance through magnetization (ARDM) and acoustic emission analysis in Vickers hardness tests. Taking into account the excitation mechanism of acoustic emission generation, which has a quasistationary stochastic character in a.c. magnetization and a transient nature in hardness testing, a microcomputerized device has been constructed for frequency analysis of the body sound level in ARDM evaluation and for measuring the pulse sum and/or pulse rate during indentation of the test specimen in hardness evaluation. Prerequisite for evaluating the measured values is the knowledge of the frequency dependence of the sensors and the instrument system. The results obtained are presented. (author)

Phase formation kinetics, hardness and magnetocaloric effect of sub-rapidly solidified LaFe11.6Si1.4 plates during isothermal annealing

Science.gov (United States)

Dai, Yuting; Xu, Zhishuai; Luo, Zhiping; Han, Ke; Zhai, Qijie; Zheng, Hongxing

2018-05-01

High-temperature phase transition behavior and intrinsic brittleness of NaZn13-type τ1 phase in La-Fe-Si magnetocaloric materials are two key problems from the viewpoint of materials production and practical applications. In the present work, the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation was introduced to quantitatively characterize the formation kinetics of τ1 phase in sub-rapidly solidified LaFe11.6Si1.4 plates during the isothermal annealing process. Avrami index was estimated to be 0.43 (∼0.5), which suggests that the formation of τ1 phase is in a diffusion-controlled one-dimensional growth mode. Meanwhile, it is found that the Vickers hardness as a function of annealing time for sub-rapidly solidified plates also agrees well with the JMAK equation. The Vickers hardness of τ1 phase was estimated to be about 754. Under a magnetic field change of 30 kOe, the maximum magnetic entropy change was about 22.31 J/(kg·K) for plates annealed at 1323 K for 48 h, and the effective magnetic refrigeration capacity reached 191 J/kg.

The effect of acidulated phosphate fluoride application on dental enamel surfaces hardness

Directory of Open Access Journals (Sweden)

Edhie Arief P

2007-09-01

Full Text Available Enamel demineralization by acid is the first step of caries process. It has recently been shown that acidulated phosphate fluoride (APF can maintain the hardness of enamel surface. The aim of this study was examine the effect of APF application in the hardest of enamel surface. Fifty extracted teeth were cut at their crown, 40 teeth were taken randomly then divided into 4 groups, group 1 as the control, group 2 was treated with APF for 1 minute, group 3 for 4 minutes and group 4 for 7 minutes, then all the samples were washed with demineralized water. To see the effect of APF, all of the samples were soaked in lactic acid demineralization solution with pH 4,5 for 72 hours., the hardness of the surfaces of those samples before and after the treatment was measured by Micro Vickers Hardness Tester. The data were analyzed using One-Way ANOVA and LSD tests. In conclusion, 1.23% APF gel can reduce higher enamel demineralization.

Hardness distribution and effect of irradiation in FSW-ODS ferritic steels

International Nuclear Information System (INIS)

Noh, Sanghoon; Kasada, Ryuta; Kimura, Akihiko; Nagasaka, Takuya; Sokolov, M.A.; Yamamoto, T.

2014-01-01

Oxide dispersion strengthened ferritic steels (ODS-FS) have been considered as one of the most promising structural materials for advanced nuclear systems such as fusion reactors and next generation fission reactors, because of its excellent elevated temperature strength, corrosion and radiation resistance. Especially, irradiation resistance is a critical issue for the high performance of ODS-FS. In this study, effects of the irradiation on hardness properties of friction stri processed (FSP) ODS-FS were investigated. FSP technique was employed on ODS-FS. A plate specimen was cut out from the cross section and irradiated to 1.2 dpa at 573K in the High Flux Isotope Reactor (HFIR). To investigate the effect of neutron irradiation on processed area, the hardness distributions were evaluated on the cross section. Hardness of FSP ODS-FS was various with each microstructure after irradiation to 1.2 dpa at 573K. The increase of Vickers hardness was significant in the stirred zone and heat affected zone. Base material exhibited the lowest hardening about 38HV. Since nano-oxide particles in stirred zone showed identical mean diameter and number density, it is considered that hardening differences between stirred zone and base material is due to differences in initial dislocation density. (author)

Effects of alpha radiation on hardness and toughness of the borosilicate glass applied to radioactive wastes immobilization

International Nuclear Information System (INIS)

Prado, Miguel Oscar; Bernasconi, Norma B. Messi de; Bevilacqua, Arturo Miguel; Arribere, Maria Angelica; Heredia, Arturo D.; Sanfilippo, Miguel

1999-01-01

Borosilicate german glass SG7 samples, obtained by frit sintering, were irradiated with different fluences of thermal neutrons in the nucleus of a nuclear reactor. The nuclear reaction 10 B(n,α) 7 Li, where the 10 B isotope is one of the natural glass components, was used to generate alpha particles throughout the glass volume. The maximum alpha disintegration per unit volume achieved was equivalent to that accumulated in a borosilicate glass with nuclear wastes after 3.8 million years. Through Vickers indentations values for microhardness, stress for 50% fracture probability (Weibull statistics) and estimation of the toughness were obtained as a function of alpha radiation dose. Two counterbalanced effects were found: that due to the disorder created by the alpha particles in the glass and that due to the annealing during irradiation (temperature below 240 deg C). Considering the alpha radiation effect, glasses tend decrease Vickers hardness, and to increase thr 50% fracture probability stress with the dose increase. (author)

Determination of the penetration hardness and analysis of stainless steel alloys by means of Laser Induced Breakdown Spectroscopy (LIBS

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mohamad Vahid Dastjerdi

2017-11-01

Full Text Available A significant feature of alloys is the surfaces hardness that is always accompanied by challenges when it’s measured by common mechanical techniques. In this investigation, we used Laser Induced Breakdown Spectroscopy (LIBS as a replacement method for common mechanical techniques to measure the surfaces hardness of different alloys. After recording the spectrum of alloy samples in order to identify the surface hardness of analyzed sample, K-Nearest Neighbors method (KNN was used and obtained results showed that the LIBS-KNN method can separate and identify the surfaces hardness of samples with precision of 93.3%. In addition, in order to identify the percentage of constituent elements of alloys and their hardness, calibration approach was investigated that showed there is an appropriate linear relation between recorded emission lines from the LIB spectra of sample alloys and the percentage of their constituent elements and also their Vickers hardness numbers. Therefore, According to exclusive advantages of LIBS technique i.e. high speed analysis, non-destructive analysis and being portable, some of available difficulties in conventional mechanical techniques can be removed.

Vickers Terminator. Volume 3C(VT) - Technical appraisal. Consultants' 1983 report

Energy Technology Data Exchange (ETDEWEB)

1986-01-01

A report is given by a team of consultants on the estimated cost of converting wave energy to electrical energy by a 2 GW array of Vickers Terminator wave energy devices and delivering the electricity to a sub-station on the west coast of Skye. Comparisons with the estimates made by the team developing the concept are presented and are largely in agreement, except for the capital cost per device and the power chain efficiency. A detailed engineering assessment is given.

Thermal-aging evaluation of on site aged cast duplex stainless steel

International Nuclear Information System (INIS)

Yamada, Takuyo; Fujii, Katsuhiko; Aoki, Masanori; Arioka, Koji

2013-01-01

In this study, thermal-aging evaluation has been performed using service aged elbow pipe in PWR plant, aged at 320degC for 196,500h. As a result, micro Vickers hardness of ferrite in service material (SCS14A), HV(0.025) was 616∼630. Since micro Vickers hardness of un-aged ferrite phase is about HV(0.025)=300 in commercial SCS14A, the increasing of ferrite hardness during aging was 300. Cr-rich and Fe-rich regions were observed in the ferrite phase using Atom-probe analysis. In addition, Ni, Si and Mo clustering were also observed in the ferrite phase. So the ferrite phase was hardened caused by these micro-structural changes. Micro Vickers hardness of austenite phase, HV(0.025) was 155∼180. Since micro Vickers hardness of un-aged austenite phase is about HV(0.025)=180∼200, and no micro-structural change was observed in the austenite phase, so on change was observed in the austenite phase during aging. To compare the micro Vickers hardness of ferrite in service and accelerated materials using activation energy, Q=100 kJ/mol, the ferrite hardness of in service material was very low rather than predictive line. This seems the activation energy was too conservative. (author)

The relationship between the hardness and the point-defect-density in neutron-irradiated MgO·3.0Al2O3 and AlN

International Nuclear Information System (INIS)

Suematsu, H.; Yatsui, K.; Yano, T.

2001-01-01

MgO·3.0Al 2 O 3 single crystals and sintered AlN polycrystals were irradiated with fast neutrons in various conditions and the hardness of the irradiated and unirradiated samples was measured with a Vickers hardness tester. The hardness of as-irradiated MgO·3.0Al 2 O 3 and AlN samples increased by 23 and 51%, respectively. After isochronal annealing, the hardness gradually decreased and mostly recovered to that of the unirradiated one up to 1400degC. Volume of the sample also increased after the irradiation and changed in the same way as the hardness by annealing. A relationship between the hardness and the density of point defects is proposed and the experimental results agree with the relationship. It implies that the point defects generated by the irradiation pin down dislocations and increase the hardness of neutron irradiated MgO·3.0Al 2 O 3 samples. (author)

Vickers microhardness comparison of 4 composite resins with different types of filler.

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René García-Contreras

2015-10-01

Full Text Available Composite resins are the material of choice to restore minimal invasive cavities; conversely, it is important to explore the mechanical properties of commercially available dental materials. Objective: To compare the Vickers microhardness (VHN of four available commercial composite resins using standardized samples and methods. Methodology: Composite cylinders were manufactured in a Teflon mould. We used the follow composite resins (n=4/gp: Microhybrid resins [Feeling Lux (Viarden and Amelogen Plus (Ultradent], Hybrid resin [Te-Econom Plus (Ivoclar] and Nanohybrid resin [Filtek Z350 (3M ESPE]. All samples were incubated in distilled water at 37ºC for five days. The test was carried out with microhardness indenter at 10 N, and a dwelling time of 10 s for 9 indentations across the specimens resulting in a total of 36 indentations for each group. Data were subjected to Kolmogorov-Smirnov normality test and ANOVA (post-hoc Tukey test. Results: The VHN mean values ranged from harder to softer as follows: Filtek Z350 (71.96±6.44 (p Amelogen Plus (59.90±4.40 (p Feeling lux (53.52±5.72> Te-Econom Plus (53.26±5.19. Conclusion: According to our results, the microhardness of the evaluated conventional composite resins can withstand the masticatory forces; however nanohybrid composite resins showed better Vickers microhardness and therefore are a more clinically suitable option for minimal invasion treatments.

Microstructure evolution and hardness change in ordered Ni3V intermetallic alloy by energetic ion irradiation

International Nuclear Information System (INIS)

Hashimoto, A.; Kaneno, Y.; Semboshi, S.; Yoshizaki, H.; Saitoh, Y.; Okamoto, Y.; Iwase, A.

2014-01-01

Ni 3 V bulk intermetallic compounds with ordered D0 22 structure were irradiated with 16 MeV Au ions at room temperature. The irradiation induced phase transformation was examined by means of the transmission electron microscope (TEM), the extended X-ray absorption fine structure measurement (EXAFS) and the X-ray diffraction (XRD). We also measured the Vickers hardness for unirradiated and irradiated specimens. The TEM observation shows that by the Au irradiation, the lamellar microstructures and the super lattice spot in diffraction pattern for the unirradiated specimen disappeared. This TEM result as well as the result of XRD and EXAFS measurements means that the intrinsic D0 22 structure of Ni 3 V changes into the A1 (fcc) structure which is the lattice structure just below the melting point in the thermal equilibrium phase diagram. The lattice structure change from D0 22 to A1 (fcc) accompanies a remarkable decrease in Vickers microhardness. The change in crystal structure was discussed in terms of the thermal spike and the sequential atomic displacements induced by the energetic heavy ion irradiation

High Frequency Acoustic Microscopy for the Determination of Porosity and Young's Modulus in High Burnup Uranium Dioxide Nuclear Fuel

Science.gov (United States)

Marchetti, Mara; Laux, Didier; Cappia, Fabiola; Laurie, M.; Van Uffelen, P.; Rondinella, V. V.; Wiss, T.; Despaux, G.

2016-06-01

During irradiation UO2 nuclear fuel experiences the development of a non-uniform distribution of porosity which contributes to establish varying mechanical properties along the radius of the pellet. Radial variations of both porosity and elastic properties in high burnup UO2 pellet can be investigated via high frequency acoustic microscopy. For this purpose ultrasound waves are generated by a piezoelectric transducer and focused on the sample, after having travelled through a coupling liquid. The elastic properties of the material are related to the velocity of the generated Rayleigh surface wave (VR). A UO2 pellet with a burnup of 67 GWd/tU was characterized using the acoustic microscope installed in the hot cells of the JRC-ITU at a 90 MHz frequency, with methanol as coupling liquid. VR was measured at different radial positions. A good agreement was found, when comparing the porosity values obtained via acoustic microscopy with those determined using SEM image analysis, especially in the areas close to the centre. In addition, Young's modulus was calculated and its radial profile was correlated to the corresponding burnup profile and to the hardness radial profile data obtained by Vickers micro-indentation.

Hardness of model dental composites - the effect of filler volume fraction and silanation.

Science.gov (United States)

McCabe, J F; Wassell, R W

1999-05-01

The relationship between structure and mechanical properties for dental composites has often proved difficult to determine due to the use of commercially available materials having a number of differences in composition i.e. different type of resin, different type of filler, etc. This makes a scientific study of any one variable such as filler content difficult if not impossible. In the current study it was the aim to test the hypothesis that hardness measurements of dental composites could be used to monitor the status of the resin-filler interface and to determine the efficacy of any particle silanation process. Ten model composites formulated from a single batch of resin and containing a common type of glass filler were formulated to contain varying amounts of filler. Some materials contained silanated filler, others contained unsilanated filler. Specimens were prepared and stored in water and hardness (Vickers') was determined at 24 h using loads of 50, 100, 200 and 300 g. Composites containing silanated fillers were significantly harder than materials containing unsilanated fillers. For unsilanated products hardness was independent of applied load and in this respect they behaved like homogeneous materials. For composites containing silanated fillers there was a marked increase in measured hardness as applied load was increased. This suggests that the hardness-load profile could be used to monitor the status of the resin-filler interface. Copyright 1999 Kluwer Academic Publishers

Effect of Ar ion on the surface properties of low density polyethylene

Science.gov (United States)

Zaki, M. F.

2016-04-01

In this paper, low-density polyethylene (LDPE) was irradiated by argon ion with different fluences up to 1015ions/cm2. The optical, chemical and hardness properties have been investigated using UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and micro-indentation tester, respectively. The results showed the ion beam bombardment induced decreases in the transmittance of the irradiated polymer samples. This change in transmittance can be attributed to the formation of conjugated bonds i.e. possible formation of defects and/or carbon clusters. The indirect optical band gap decreased from 3.0 eV for the pristine sample to 2.3 eV for that sample irradiated with the highest fluence of the Ar ion beam. Furthermore, the number of carbon atoms and clusters increased with increasing Ar ion fluences. FTIR spectra showed the formation of new bands of the bombarded polymer samples. Furthermore, polar groups were created on the surface of the irradiated samples which refer to the increase of the hydrophilic nature of the surface of the irradiated samples. The Vicker's hardness increased from 4.9 MPa for the pristine sample to 17.9 MPa for those bombarded at the highest fluence. This increase is attributed to the increase in the crosslinking and alterations of the bombarded surface into hydrogenated amorphous carbon, which improves the hardness of the irradiated samples. The bombarded LDPE surfaces may be used in special applications to the field of the micro-electronic devices and shock absorbers.

Elastic modulus, hardness and fracture behavior of Pb(Zn1/3Nb2/3)O3-PbTiO3 single crystal

International Nuclear Information System (INIS)

Zeng Kaiyang; Pang Yongsong; Shen Lu; Rajan, K.K.; Lim, Leong-Chew

2008-01-01

The deformation, crack initiation, fracture behavior and mechanical properties of (0 0 1)-oriented single crystal of Pb(Zn 1/3 Nb 2/3 )O 3 -7% PbTiO 3 (PZN-7% PT) in both unpoled and poled states have been investigated by using nanoindentation, micro-indentation and three-point bending experiments. Nanoindentation experiments revealed that, unlike typical brittle materials, material pile-ups around the indentation impressions were commonly observed at ultra-low loads. The elastic modulus and hardness were also determined by using nanoindentation experiments. The critical indentation load for crack initiation, determined by using micro-indentation experiments, is 0.135 N for unpoled samples, increasing to 0.465 N for the positive surface (crack propagation direction against the poling direction) of poled samples but decreasing slightly to 0.132 N for the negative surface (crack propagation direction along the poling direction) of the poled samples. Indentation/strength (three-point bend) test showed a similar trend for the 'apparent' fracture toughness, giving 0.36 MPa√m for unpoled samples, increasing to 0.44 MPa√m for the positive surface of poled samples but decreasing to 0.30 MPa√m for the negative surface of poled samples. Polarized light microscopy and scanning electron microscopy were used to study the material adjacent to the indentations and the fracture surfaces produced by the three-point bend tests. The results were correlated with the various fracture properties observed

Correlation between hardness and stress in Al-(Nb, Mo, Ta) thin films

Energy Technology Data Exchange (ETDEWEB)

Car, T., E-mail: car@irb.h [Rudjer Boskovic Institute, Division of Materials Science, Bijenicka cesta 54, 10000 Zagreb, P.O.B. 1016 (Croatia); Radic, N. [Rudjer Boskovic Institute, Division of Materials Science, Bijenicka cesta 54, 10000 Zagreb, P.O.B. 1016 (Croatia); Panjan, P.; Cekada, M. [Jozef Stefan Institute, Ljubljana (Slovenia); Tonejc, A. [Department of Physics, Bijenicka cesta 32, 10000 Zagreb, P.O.B. 331 (Croatia)

2009-06-30

The thin films of Al{sub x}Nb{sub 1-x} (95 {>=} x {>=} 20), Al{sub x}Mo{sub x} (90 {>=} x {>=} 20) and Al{sub x}Ta{sub 1-x} (95 {>=} x {>=} 20) were prepared by magnetron codeposition at room temperature. The average film thickness was from 325 to 400 nm, depending on the film composition. The structure of the as-deposited films was examined by the X-ray diffraction. The stress of the films was determined from the substrate deformation by the profilometer, and the microhardness (load 2 mN) was examined by the micro- and nano-hardness device. For the purpose of the examination of the hardness, the samples were deposited onto the sapphire wafers, while the examination of the film stress, was performed by using thin glass substrates. For all the Al-(Nb, Mo, Ta) alloy compositions, the microhardness is predominantly under the influence of the harder element, and monotonically decreases with the increase of the aluminum content. However, the microhardness of the amorphous AlTa films was higher than the bulk value of a harder element (Ta) in the alloy. A simple empirical linear relationship between the Vickers hardness, the bulk value hardness of the transition metal (harder element) and the elastic energy fraction of the identation deformation, was established. The elastic energy fraction in the microhardness is also linearly correlated with the stress in films.

Enhanced electrical conductivity and hardness of silver-nickel composites by silver-coated multi-walled carbon nanotubes

International Nuclear Information System (INIS)

Lee, Dongmok; Sim, Jeonghyun; Baik, Seunghyun; Kim, Wonyoung; Moon, Chuldong; Cho, Wookdong

2015-01-01

We investigated electrical conductivity and Vickers hardness of Ag- and Ni-based composites prepared by powder metallurgy involving spark plasma sintering. The starting composition was Ag:Ni = 61:39 vol%, which provided an electrical conductivity of 3.30 × 10"5 S cm"−"1 and a hardness of 1.27 GPa. The addition of bare multi-walled carbon nanotubes (MWNTs, 1.45 vol%) increased hardness (1.31 GPa) but decreased electrical conductivity (2.99 × 10"5 S cm"−"1) and carrier mobility (11 cm"2 V"−"1 s"−"1) due to the formation of Ni_3C in the interface between the MWNTs and Ni during spark plasma sintering. The formation of Ni_3C was prevented by coating the surface of the nanotubes with Ag (nAgMWNTs), concomitantly increasing electrical conductivity (3.43 × 10"5 S cm"−"1) and hardness (1.37 GPa) of the sintered specimen (Ag:Ni:nAgMWNTs = 59.55:39:1.45 vol%). The electrical contact switching time (133 357) was also increased by 30%, demonstrating excellent feasibility as electrical contact materials for electric power industries. (paper)

Hardness and depth-dependent microstructure of ion-irradiated MgAl2O4

International Nuclear Information System (INIS)

Zinkle, S.J.

1988-01-01

Stoichiometric polycrystalline magnesium aluminate spinel has been irradiated at 25 and 650/degree/C with 2.4 MeV Mg/sup plus/ ions to a fluence of 1.4 /times/ 10 21 ions/m 2 (/approximately/35 dpa peak damage level). Microindentation hardness measurements and transmission electron microscopy combined with energy dispersive X-ray spectroscopy measurements were used to characterize the irradiation effects. The room-temperature hardness of spinel increased by about 5% after irradiation at both temperatures. There was no evidence for amorphization at either irradiation temperature. Interstitial-type dislocations loops lying on /l brace/110/r brace/ and /l brace/111/r brace/ planes with Burgers vectors were observed at intermediate depths (/approximately/1 μm) along the ion range. The /l brace/111/r brace/ loops are presumably formed from /l brace/111/r brace/ loops as a result of a shear on the anion sublattice. Only about 0.05% of the calculated displacements were visible in the form of loops, which indicates that spinel has a high resistance to aggregate damage accumulation. The peak damage region contained a high density of dislocations tangles. There was no evidence for the formation of voids or vacancy loops. The specimen irradiated at 650/degree/C was denuded of dislocation loops within /approximately/1 μm of the surface. 25 refs., 16 figs., 5 tabs

Mechanical properties of materials used for temporary fixed dentures – in vitro study

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Celej-Piszcz Elzbieta

2017-06-01

Full Text Available Objectives. The objective of the research was to define the mechanical properties of currently marketed temporary filling materials. Methods. Eight temporary filling materials: Boston, Dentalon, Protemp II, Revotek LC, Structure 2, Structure 3, UniFast LC, UniFast Trad were used to make 5 samples each of measurements 2 × 2 × 25 mm, in order to define the flexural strength, and 10 rings each of measurements 2 × 5 mm, in order to carry out the Vickers micro-hardness test. After preparation, the samples were stored in distilled water of temperature of 370°C, for 7 days. Subsequently, flexural strength and Vickers hardness testing was undertaken. Results. Composite temporary materials showed considerably better mechanical properties, both in flexural strength and in Vickers micro-hardness testing. Conclusions. the best mechanical properties, both in terms of flexural strength, as well as Vickers micro-hardness test can be observe among composite materials.

Enhancing the Hardness of Sintered SS 17-4PH Using Nitriding Process for Bracket Orthodontic Application

Science.gov (United States)

Suharno, B.; Supriadi, S.; Ayuningtyas, S. T.; Widjaya, T.; Baek, E. R.

2018-01-01

Brackets orthodontic create teeth movement by applying force from wire to bracket then transferred to teeth. However, emergence of friction between brackets and wires reduces load for teeth movement towards desired area. In order to overcome these problem, surface treatment like nitriding chosen as a process which could escalate efficiency of transferred force by improving material hardness since hard materials have low friction levels. This work investigated nitriding treatment to form nitride layer which affecting hardness of sintered SS 17-4PH. The nitride layers produced after nitriding process at various temperature i.e. 470°C, 500°C, 530°C with 8hr holding time under 50% NH3 atmosphere. Optical metallography was conducted to compare microstructure of base and surface metal while the increasing of surface hardness then observed using vickers microhardness tester. Hardened surface layer was obtained after gaseous nitriding process because of nitride layer that contains Fe4N, CrN and Fe-αN formed. Hardness layers can achieved value 1051 HV associated with varies thickness from 53 to 119 μm. The presence of a precipitation process occurring in conjunction with nitriding process can lead to a decrease in hardness due to nitrogen content diminishing in solid solution phase. This problem causes weakening of nitrogen expansion in martensite lattice.

The effect of nitrogen gas flow rate on heat treatment of AISI SS-430: Study of microstructure and hardness

Science.gov (United States)

Sebayang, Perdamean; Darmawan, Bobby Aditya; Simbolon, Silviana; Alfirano, Sudiro, Toto; Aryanto, Didik

2018-05-01

The aim of this research was to obtain the austenite phase from ferritic stainless steel through sample heat treatment. The AISI 430 ferritic steel with the thickness of about 0.4 mm was used. The heat treatment was conducted in a tube furnace at elevated temperature of 1150, 1200, 1250 °C and nitrogen gas flow rate of 0.57 and 0.73 l/s. The samples were then rapidly quenched in water bath. An optical microscope, XRD, SEM-EDS and micro vickers hardness tester were used to characterize the sample before and after het treatment. The presence of anneal twins indicated the formation of austenite phase in the sample. Its fraction was varied from 10.89 wt% to 35.10 wt%. In addition, the heat treatment temperature strongly affected the sample hardness. The optimum hardness obtained was about 542.69 HV. According to the results, this material can be considered for biomedical applications.

Local microstructures, Hardness and mechanical properties of a stainless steel pipe-welded joint

International Nuclear Information System (INIS)

Zhao Yongxiang; Gao Qing; Cai Lixun

2000-01-01

An experimental investigation is carefully performed into the local microstructures, hardness values and monotonic mechanical properties of the three zones (the base metal, heat affecting zone and weld metal) of 1Cr18Ni9Ti stainless steel pipe-welded joint. The local microstructures are observed by a metallurgical test and a surface replica technology, the local hardness values are measures by a random Vickers hardness test, and the local mechanical properties are characterized by the Ramberg-Osgood and modified Ramberg-Osgood stress-stain relations. The investigation reveals that there are significant differences of the three zones in the local microstructures, hardness values and monotonic mechanical properties, especially of the three zones in the local microstructure, hardness values and monotonic mechanical properties, especially of the weld metal. The weld metal exhibits the largest heterogeneity of local microstructures and monotonic mechanical properties, and the largest scatter of local hardness values. It is necessary to consider these difference and introduce the reliability method to model the scatter in the pipe analysis. In addition, it is verified that a columnar grain structure, which is made up of matrix-rich δ ferrite bands, can characterize the weld metal and the distance between the neighboring rich δ ferrite bands is an appropriate measurement of the columnar grain structure. This measurement is in accordance with the transition point between the microstructural short crack and physical small crack stages, which are generally used for characterizing the short fatigue crack behavior of materials. This indicates that the microstructure controls the fatigue damage character of the present material

A study on hardness behavior of geopolymer paste in different condition

Science.gov (United States)

Zainal, Farah Farhana; Hussin, Kamarudin; Rahmat, Azmi; Abdullah, Mohd Mustafa Al Bakri; Shamsudin, Shaiful Rizam

2016-07-01

This study has been conducted to understand the hardness behavior of geopolymer paste in different conditions; with and without being immersed in water. Geopolymer paste has been used nowadays as an alternative way to reduce global warming pollution by carbon dioxide (CO2) released to the air caused from the production of Ordinary Portland Cement (OPC). Geopolymer has many advantages such as high compressive strength, lower water absorption and lower porosity. Geopolymer paste in this study was made from a mixture of fly ash and alkaline activators. The alkaline activators that have been used were sodium hydroxide (NaOH) solution and sodium silicate (Na2SiO3) solution. Then the mixture was allowed to harden for 24hrs at ambient temperature and then placed in the oven for 24hrs with 60°C for the curing process. The hardness testing was conducted after a few months when the samples already achieved the optimum design. The samples were divided to two conditions; without immersion which was placed at ambient temperature (S1) and immersed in water for one week (S2). The samples then are divided into two at the center and testing was conducted into 4 parts which are part 1, part 2, part 3 and part 4. Various methods of non-destructively testing concrete and mortar have been in use for many years such as Vickers hardness test, Rockwell hardness test, Brinell hardness test and many more. The Rockwell hardness test method as defined in ASTM E-18 is the most commonly used hardness test method which is also used in this study. From the results, S1 has higher hardness value than S2 for all parts with the maximum value of S1 is 118.6 and the minimum value is 71.8. The maximum value of S2 is 114.4 and the minimum value is 0. The central part of the geopolymer paste also showed greater hardness values than the edge area of the samples.

Fracture toughness of glasses and hydroxyapatite: a comparative study of 7 methods by using Vickers indenter

OpenAIRE

HERVAS , Isabel; MONTAGNE , Alex; Van Gorp , Adrien; BENTOUMI , M.; THUAULT , A.; IOST , Alain

2016-01-01

International audience; Numerous methods have been proposed to estimate the indentation fracture toughness Kic for brittle materials. These methods generally uses formulæ established from empirical correlations between critical applied force, or average crack length, and classical fracture mechanics tests. This study compares several models of fracture toughness calculation obtained by using Vickers indenters. Two optical glasses (Crown and Flint), one vitroceramic (Zerodur) and one ceramic (...

Accelerated aging effects on surface hardness and roughness of lingual retainer adhesives.

Science.gov (United States)

Ramoglu, Sabri Ilhan; Usumez, Serdar; Buyukyilmaz, Tamer

2008-01-01

To test the null hypothesis that accelerated aging has no effect on the surface microhardness and roughness of two light-cured lingual retainer adhesives. Ten samples of light-cured materials, Transbond Lingual Retainer (3M Unitek) and Light Cure Retainer (Reliance) were cured with a halogen light for 40 seconds. Vickers hardness and surface roughness were measured before and after accelerated aging of 300 hours in a weathering tester. Differences between mean values were analyzed for statistical significance using a t-test. The level of statistical significance was set at P statistically significant (P statistically significant (P .05). Accelerated aging significantly increased the surface microhardness of both light-cured retainer adhesives tested. It also significantly increased the surface roughness of the Transbond Lingual Retainer.

Effects of the bleaching procedures on enamel micro-hardness: Plasma Arc and diode laser comparison.

Science.gov (United States)

Nematianaraki, Saeid; Fekrazad, Reza; Naghibi, Nasim; Kalhori, Katayoun Am; Junior, Aldo Brugnera

2015-10-02

One of the major side effects of vital bleaching is the reduction of enamel micro-hardness. The purpose of this study was to evaluate the influence of two different bleaching systems, Plasma Arc and GaAlAs laser, on the enamel micro-hardness. 15 freshly extracted human third molars were sectioned to prepare 30 enamel blocks (5×5 mm). These samples were then randomly divided into 2 groups of 15 each (n=15): a plasma arc bleaching group (: 350-700 nm) + 35% Hydrogen Peroxide whitening gel and a laser bleaching group (GaAlAs laser, λ: 810 nm, P: 10 W, CW, Special Tip) + 35% Hydrogen Peroxide whitening gel. Samples were subjected to the Vickers micro-hardness test (VHN) at a load of 50 g for 15s before and after treatment. Data were statistically analyzed by a Mann-Whitney test (p≤0.05). In the GaAlAs laser group, the enamel micro-hardness was 618.2 before and was reduced to 544.6 after bleaching procedures. In the plasma arc group, the enamel micro-hardness was 644.8 before and 498.9 after bleaching. Although both techniques significantly reduced VHN, plasma arc bleaching resulted in a 22.62% reduction in VHN for enamel micro-hardness, whereas an 11.89% reduction in VHN was observed for laser bleaching; this difference is statistically significant (plaser than with the plasma arc. Therefore GaAlAs laser bleaching has fewer harmful effects than plasma arc in respect to enamel micro-hardness reduction.

Anisotropy of hardness and laser damage threshold of unidirectional organic NLO crystal in relation to the internal structure

International Nuclear Information System (INIS)

Natarajan, V.; Arivanandhan, M.; Sankaranarayanan, K.; Hayakawa, Y.

2011-01-01

Highlights: · Growth rate of the unidirectional organic crystals were measured and the variation in the growth rate was explained based on the attachment energy model. · Anisotropic behaviors of hardness and laser damage threshold of the unidirectional materials were analyzed. · The obtained results were explained based on the crystal structure of the material. - Abstract: Unidirectional benzophenone crystals were grown along , and directions by uniaxially solution crystallization method at ambient temperature. The growth rate of the grown crystals was varied with orientation. The optical absorption coefficients of benzophenone were measured as a function of wavelength. The optical absorption study reveals that the benzophenone crystal has very low absorption in the wavelength range of interest. Moreover, the laser damage threshold and micro hardness for , and oriented unidirectional benzophenone crystals were measured using a Q-switched Nd:YAG laser operating at 1064 nm radiation and Vicker's micro hardness tester, respectively. The laser damage threshold is larger for the and oriented crystals compared to oriented crystal at 1064 nm wavelength. The result is consistent with the hardness variation observed for the three different crystallographic directions of benzophenone crystal. The relation between the laser damage profile and mechanical hardness anisotropy is discussed based on the crystal structure of benzophenone.

Effects of delayed finishing/polishing on surface roughness, hardness and gloss of tooth-coloured restorative materials.

Science.gov (United States)

Yazici, A Ruya; Tuncer, Duygu; Antonson, Sibel; Onen, Alev; Kilinc, Evren

2010-01-01

The aim of this study was to investigate the effect of delayed finishing/polishing on the surface roughness, hardness and gloss of tooth-coloured restorative materials. Four different tooth-coloured restoratives: a flowable resin composite- Tetric Flow, a hybrid resin composite- Venus, a nanohybrid resin composite- Grandio, and a polyacid modified resin composite- Dyract Extra were used. 30 specimens were made for each material and randomly assigned into three groups. The first group was finished/polished immediately and the second group was finished/polished after 24 hours. The remaining 10 specimens served as control. The surface roughness of each sample was recorded using a laser profilometer. Gloss measurements were performed using a small-area glossmeter. Vickers microhardness measurements were performed from three locations on each specimen surface under 100g load and 10s dwell time. Data for surface roughness and hardness were analyzed by Kruskal Wallis test and data for gloss were subjected to one-way ANOVA and Tukey test (P gloss values were recorded under Mylar strip for all materials. While delayed finishing/polishing resulted in a significantly higher gloss compared to immediate finishing/polishing in Venus samples (P .05). The lowest hardness values were found under Mylar strip. Delayed finishing/polishing significantly increased the hardness of all materials. The effect of delayed finishing/polishing on surface roughness, gloss and hardness appears to be material dependent.

Fracture toughness measurements on a glass bonded sodalite high-level waste form

International Nuclear Information System (INIS)

DiSanto, T.; Goff, K. M.; Johnson, S. G.; O'Holleran, T. P.

1999-01-01

The electrometallurgical treatment of metallic spent nuclear fuel produces two high-level waste streams; cladding hulls and chloride salt. Argonne National Laboratory is developing a glass bonded sodalite waste form to immobilize the salt waste stream. The waste form consists of 75 Vol.% crystalline sodalite (containing the salt) with 25 Vol.% of an ''intergranular'' glassy phase. Microindentation fracture toughness measurements were performed on representative samples of this material using a Vickers indenter. Palmqvist cracking was confirmed by post-indentation polishing of a test sample. Young's modulus was measured by an acoustic technique. Fracture toughness, microhardness, and Young's modulus values are reported, along with results from scanning electron microscopy studies

Micromechanical properties of C70 single crystals in the temperature range 77-350 K

International Nuclear Information System (INIS)

Lubenets, S.V.; Natsik, V.D.; Fomenko, L.S.; Rusakova, A.V.; Natsik, V.D.; Osip'yan, Yu.A.; Orlov, V.I.; Sidorov, N.S.; Izotov, A.N.

2012-01-01

Hexagonal single crystals of C 70 up to a size down to 1-2 mm were grown which allowed for the first time to investigate their low-temperature mechanical properties. Morphology, microplasticity anisotropy and the temperature dependence of Vickers microhardness HV (T) of the C 70 crystals in the temperature range 77-350 K involving all known phase transitions have been studied with the aid of optical microscopy and microindentation. The association of the features of HV (T) dependence with orientation phase transformations has been analyzed. It is suggested that anisotropy of microplasticity in the C 70 crystals correlates with the active slip systems.

Enhanced Mechanical Properties of Laser Treated Al-Cu Alloys : A Microstructural Analysis

NARCIS (Netherlands)

Mol van Otterloo, J.L.de; Bagnoli, D.; de Hosson, J.T.M.

Both mechanical Vickers hardness and electron microscopic studies have been carried out on laser treated aluminium copper alloys with a copper concentration in the range 0-40 wt%. It is found that a Vickers hardness of 470 kgf/mm(2) can be attained, which is high compared to a value of 120 kgf/mm(2)

Thermal processing of polycrystalline NiTi shape memory alloys

International Nuclear Information System (INIS)

Frick, Carl P.; Ortega, Alicia M.; Tyber, Jeffrey; Maksound, A.El.M.; Maier, Hans J.; Liu Yinong; Gall, Ken

2005-01-01

The objective of this study is to examine the effect of heat treatment on polycrystalline Ti-50.9 at.% Ni in hot-rolled and cold-drawn states. In particular, we examine microstructure, transformation temperatures as well as mechanical behavior in terms of both uniaxial monotonic testing and instrumented Vickers micro-indentation. The results constitute a fundamental understanding of the effect of heat treatment on thermal/stress-induced martensite and resistance to plastic flow in NiTi, all of which are critical for optimizing the mechanical properties. The high temperature of the hot-rolling process caused recrystallization, recovery, and hindered precipitate formation, essentially solutionizing the NiTi. The subsequent cold-drawing-induced a high density of dislocations and martensite. Heat treatments were carried out on hot-rolled, as well as, hot-rolled then cold-drawn materials at various temperatures for 1.5 h. Transmission Electron Microscopy observations revealed that Ti 3 Ni 4 precipitates progressively increased in size and changed their interface with the matrix from being coherent to incoherent with increasing heat treatment temperature. Accompanying the changes in precipitate size and interface coherency, transformation temperatures were observed to systematically shift, leading to the occurrence of the R-phase and multiple-stage transformations. Room temperature stress-strain tests illustrated a variety of mechanical responses for the various heat treatments, from pseudoelasticity to shape memory. The changes in stress-strain behavior are interpreted in terms of shifts in the primary martensite transformation temperatures, rather then the occurrence of the R-phase transformation. The results confirm that Ti 3 Ni 4 precipitates can be used to elicit a desired isothermal stress-strain behavior in polycrystalline NiTi. Instrumented micro-indention tests revealed that Martens (Universal) Hardness values are more dependent on the resistance to dislocation

Prediction of the Vickers Microhardness and Ultimate Tensile Strength of AA5754 H111 Friction Stir Welding Butt Joints Using Artificial Neural Network.

Science.gov (United States)

De Filippis, Luigi Alberto Ciro; Serio, Livia Maria; Facchini, Francesco; Mummolo, Giovanni; Ludovico, Antonio Domenico

2016-11-10

A simulation model was developed for the monitoring, controlling and optimization of the Friction Stir Welding (FSW) process. This approach, using the FSW technique, allows identifying the correlation between the process parameters (input variable) and the mechanical properties (output responses) of the welded AA5754 H111 aluminum plates. The optimization of technological parameters is a basic requirement for increasing the seam quality, since it promotes a stable and defect-free process. Both the tool rotation and the travel speed, the position of the samples extracted from the weld bead and the thermal data, detected with thermographic techniques for on-line control of the joints, were varied to build the experimental plans. The quality of joints was evaluated through destructive and non-destructive tests (visual tests, macro graphic analysis, tensile tests, indentation Vickers hardness tests and t thermographic controls). The simulation model was based on the adoption of the Artificial Neural Networks (ANNs) characterized by back-propagation learning algorithm with different types of architecture, which were able to predict with good reliability the FSW process parameters for the welding of the AA5754 H111 aluminum plates in Butt-Joint configuration.

Prediction of the Vickers Microhardness and Ultimate Tensile Strength of AA5754 H111 Friction Stir Welding Butt Joints Using Artificial Neural Network

Directory of Open Access Journals (Sweden)

Luigi Alberto Ciro De Filippis

2016-11-01

Full Text Available A simulation model was developed for the monitoring, controlling and optimization of the Friction Stir Welding (FSW process. This approach, using the FSW technique, allows identifying the correlation between the process parameters (input variable and the mechanical properties (output responses of the welded AA5754 H111 aluminum plates. The optimization of technological parameters is a basic requirement for increasing the seam quality, since it promotes a stable and defect-free process. Both the tool rotation and the travel speed, the position of the samples extracted from the weld bead and the thermal data, detected with thermographic techniques for on-line control of the joints, were varied to build the experimental plans. The quality of joints was evaluated through destructive and non-destructive tests (visual tests, macro graphic analysis, tensile tests, indentation Vickers hardness tests and t thermographic controls. The simulation model was based on the adoption of the Artificial Neural Networks (ANNs characterized by back-propagation learning algorithm with different types of architecture, which were able to predict with good reliability the FSW process parameters for the welding of the AA5754 H111 aluminum plates in Butt-Joint configuration.

Microstructure and hardness investigation of 17-4PH stainless steel by laser quenching

Energy Technology Data Exchange (ETDEWEB)

Chen Zhaoyun, E-mail: zhaoyunchenlaoshi@126.com [College of Materials Science and Chemical Engineering, Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, Harbin Engineering University, Nantong ST 145, Harbin 150001 (China); Zhou Guijuan, E-mail: zgjghpx@126.com [College of Materials Science and Chemical Engineering, Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, Harbin Engineering University, Nantong ST 145, Harbin 150001 (China); Chen Zhonghua, E-mail: jickdahua@163.com [College of Materials Science and Chemical Engineering, Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, Harbin Engineering University, Nantong ST 145, Harbin 150001 (China)

2012-02-01

Highlights: Black-Right-Pointing-Pointer Surface hardening of 17-4PH is highly achieved by laser transformation hardening. Black-Right-Pointing-Pointer A hardened layer with a thickness of 1.75 mm is formed. Black-Right-Pointing-Pointer The phase similar to {epsilon}-Cu precipitates re-segregation after dissolved. Black-Right-Pointing-Pointer The strengthening phase is composed of classic lath martensite, coarse NbC and a lot of finer fcc copper-rich phases. - Abstract: Surface hardening of 17-4PH was achieved by laser transformation hardening using 5 kW continuous wave CO{sub 2} laser system. The microstructure of the laser-quenched sample was investigated by optical microscopy, transmission electron microscope and {sup 57}Fe Moessbauer spectrometer. The hardness profile was determined by a Vickers hardness tester. The hardened layer with a thickness of 1.75 mm was formed, and it was composed of classic lath martensite, coarse NbC and a lot of finer fcc copper-rich phases which were similar to {epsilon}-Cu precipitates. The maximal hardness value of hardened zone is 446 HV which is 50 HV higher than that of the substrate (386-397 HV). The higher hardness in laser transformation layer of the 17-4PH steel could be attributed to the following aspects: the matrix with a high dislocation density; the fine microstructure; the finer fcc copper-rich phases that were similar to the {epsilon}-Cu precipitates as well as the transforming of retained austenite into lath martensite.

Effect of Nb element content in U-Zr-Nb alloy on hardness, microstructure and phase formation

International Nuclear Information System (INIS)

Masrukan; M Husna Al Hasa; Jan Setiawan; Slamet Pribadi

2015-01-01

Experiments to determine the effect of Nb element in the U-Zr alloys on hardness, microstructure and phase formation has been done. The addition of Nb element would effect the hardness, microstructure and phase which formed. The U-Zr-Nb alloy was made with the variation of Nb 2%, 5% and 8% by melting in an electric arc melting furnace that equipped with water cooling and the argon atmosphere. The U-Zr-Nb alloy to be cut divided to some testing, such as hardness test, microstructure, and phase analysis. Hardness testing was done by Vickers hardness testing equipment, microstructure by an optical microscope, and diffraction pattern by XRD and phase analysis was done by GSAS. Hardness testing results showed that the addition of 2% to 5% Nb element in U-Zr alloys will increased in hardness, but the addition of Nb element over 5% the hardness was decreased. Observations the microstructure showed that the addition of 2% to 5% Nb element, grains were formed from fine into coarse. Phase analysis for diffraction pattern showed that the phase changed from αU and γU (Zr,Nb)at 2% Nb to be αU, γU (Zr,Nb) and δ1 (UZr_2) phase at 5% and 8% Nb. Phase changes was followed by changes in its compositions. The composition of αU at 2% Nb was 40% increased to 81% at 5% Nb and decreased to 3.9% at 8% Nb. The composition of γU decreased from 59,86% to 14,91% with increased Nb from 2% to 5% and further increased to 52,74% at 8% Nb. (author)

Characterization of AISI 4140 borided steels

International Nuclear Information System (INIS)

Campos-Silva, I.; Ortiz-Dominguez, M.; Lopez-Perrusquia, N.; Meneses-Amador, A.; Escobar-Galindo, R.; Martinez-Trinidad, J.

2010-01-01

The present study characterizes the surface of AISI 4140 steels exposed to the paste-boriding process. The formation of Fe 2 B hard coatings was obtained in the temperature range 1123-1273 K with different exposure times, using a 4 mm thick layer of boron carbide paste over the material surface. First, the growth kinetics of boride layers at the surface of AISI 4140 steels was evaluated. Second, the presence and distribution of alloying elements on the Fe 2 B phase was measured using the Glow Discharge Optical Emission Spectrometry (GDOES) technique. Further, thermal residual stresses produced on the borided phase were evaluated by X-ray diffraction (XRD) analysis. The fracture toughness of the iron boride layer of the AISI 4140 borided steels was estimated using a Vickers microindentation induced-fracture testing at a constant distance of 25 μm from the surface. The force criterion of fracture toughness was determined from the extent of brittle cracks, both parallel and perpendicular to the surface, originating at the tips of an indenter impression. The fracture toughness values obtained by the Palmqvist crack model are expressed in the form K C (π/2) > K C > K C (0) for the different applied loads and experimental parameters of the boriding process.

Characterization of AISI 4140 borided steels

Science.gov (United States)

Campos-Silva, I.; Ortiz-Domínguez, M.; López-Perrusquia, N.; Meneses-Amador, A.; Escobar-Galindo, R.; Martínez-Trinidad, J.

2010-02-01

The present study characterizes the surface of AISI 4140 steels exposed to the paste-boriding process. The formation of Fe 2B hard coatings was obtained in the temperature range 1123-1273 K with different exposure times, using a 4 mm thick layer of boron carbide paste over the material surface. First, the growth kinetics of boride layers at the surface of AISI 4140 steels was evaluated. Second, the presence and distribution of alloying elements on the Fe 2B phase was measured using the Glow Discharge Optical Emission Spectrometry (GDOES) technique. Further, thermal residual stresses produced on the borided phase were evaluated by X-ray diffraction (XRD) analysis. The fracture toughness of the iron boride layer of the AISI 4140 borided steels was estimated using a Vickers microindentation induced-fracture testing at a constant distance of 25 μm from the surface. The force criterion of fracture toughness was determined from the extent of brittle cracks, both parallel and perpendicular to the surface, originating at the tips of an indenter impression. The fracture toughness values obtained by the Palmqvist crack model are expressed in the form KC( π/2) > KC > KC(0) for the different applied loads and experimental parameters of the boriding process.

Characterization of AISI 4140 borided steels

Energy Technology Data Exchange (ETDEWEB)

Campos-Silva, I., E-mail: icampos@ipn.mx [Instituto Politecnico Nacional, Grupo Ingenieria de Superficies, SEPI-ESIME U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F., 07738 (Mexico); Ortiz-Dominguez, M.; Lopez-Perrusquia, N.; Meneses-Amador, A. [Instituto Politecnico Nacional, Grupo Ingenieria de Superficies, SEPI-ESIME U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F., 07738 (Mexico); Escobar-Galindo, R. [Instituto de Ciencia de Materiales de Madrid (CSIC), E-28049 Cantoblanco, Madrid (Spain); Martinez-Trinidad, J. [Instituto Politecnico Nacional, Grupo Ingenieria de Superficies, SEPI-ESIME U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F., 07738 (Mexico)

2010-02-01

The present study characterizes the surface of AISI 4140 steels exposed to the paste-boriding process. The formation of Fe{sub 2}B hard coatings was obtained in the temperature range 1123-1273 K with different exposure times, using a 4 mm thick layer of boron carbide paste over the material surface. First, the growth kinetics of boride layers at the surface of AISI 4140 steels was evaluated. Second, the presence and distribution of alloying elements on the Fe{sub 2}B phase was measured using the Glow Discharge Optical Emission Spectrometry (GDOES) technique. Further, thermal residual stresses produced on the borided phase were evaluated by X-ray diffraction (XRD) analysis. The fracture toughness of the iron boride layer of the AISI 4140 borided steels was estimated using a Vickers microindentation induced-fracture testing at a constant distance of 25 {mu}m from the surface. The force criterion of fracture toughness was determined from the extent of brittle cracks, both parallel and perpendicular to the surface, originating at the tips of an indenter impression. The fracture toughness values obtained by the Palmqvist crack model are expressed in the form K{sub C}({pi}/2) > K{sub C} > K{sub C}(0) for the different applied loads and experimental parameters of the boriding process.

Vickers Microhardness and Hyperfine Magnetic Field Variations of Heat Treated Amorphous Fe{sub 78}Si{sub 9}B{sub 13} Alloy Ribbons

Energy Technology Data Exchange (ETDEWEB)

Cabral-Prieto, A., E-mail: acpr@nuclear.inin.mx [Instituto Nacional de Investigaciones Nucleares, Department of Chemistry (Mexico); Garcia-Santibanez, F.; Lopez, A.; Lopez-Castanares, R.; Olea Cardoso, O. [Universidad Autonoma del Estado de Mexico, El Cerrillo Piedras Blancas, Facultad de Ciencias (Mexico)

2005-02-15

Amorphous Fe{sub 78}Si{sub 9}B{sub 13} alloy ribbons were heat treated between 296 and 763 K, using heating rates between 1 and 4.5 K/min. Whereas one ribbon partially crystallized at T{sub x} = 722 K, the other one partially crystallized at T{sub x} = 763 K. The partially crystallized ribbon at 722 K, heat treated using a triangular form for the heating and cooling rates, was substantially less fragile than the partially crystallized at 763 K where a tooth saw form for the heating and cooling rates was used. Vickers microhardness and hyperfine magnetic field values behaved almost concomitantly between 296 and 673 K. The Moessbauer spectral line widths of the heat-treated ribbons decreased continuously from 296 to 500 K, suggesting stress relief in this temperature range where the Vickers microhardness did not increase. At 523 K the line width decreased further but the microhardness increased substantially. After 523 K the line width behave in an oscillating form as well as the microhardness, indicating other structural changes in addition to the stress relief. Finally, positron lifetime data showed that both inner part and surface of Fe{sub 78}Si{sub 9}B{sub 13} alloy ribbons were affected distinctly. Variations on the surface may be the cause of some of the high Vickers microhardness values measured in the amorphous state.

Evaluation of material property of austenitic stainless steel using nano-indentation

Energy Technology Data Exchange (ETDEWEB)

Suyama, Takeshi [Institute of Nuclear Safety Systems Inc., Mihama, Fukui (Japan)

2001-09-01

In order to evaluate some material properties of very small area on small specimens which are sampled from components in service and to predict macroscopic material properties from the data of the small specimens, nano-indentation is considered to be quite effective. However, there are few reports formularize the dependence of load on hardness values evaluated from the results of indentation tests with loads from 10 mg to 100 g. In this study, systematic tests of indentation were conducted to specimens of austenitic stainless steel SUS304 using a Berkovich indenter and a Vickers indenter with loads varying from 10 mg to 100 g. From these results numerical formulae which relate the calculated hardness values to the loads were made. In addition, the relation between Vickers hardness and nano-indentation hardness was obtained. As a result, it became possible to predict Vickers hardness from nano-indentation with loads as low as about 100 mg. (author)

Effect of Bi-content on hardness and micro-creep behavior of Sn-3.5Ag rapidly solidified alloy

Energy Technology Data Exchange (ETDEWEB)

Kamal, M. [Metal Physics Laboratory, Faculty of Science, Mansoura University (Egypt); Gouda, El Said [Metal Physics Laboratory, Department of Solid State Physics, Physics Division, National Research Center, Dokki, Giza (Egypt); Marei, L.K. [Faculty of Petroleum and Mining Engineering, Suez Canal University, Suez (Egypt)

2009-12-15

In the present paper, the influence of 1, 3, 5 and 10 % Bi (weight %) as ternary additions on structure, melting and mechanical properties of rapidly solidified Sn-3.5Ag alloy has been investigated. The effect of Bi was discussed based on the experimental results. The experimental results showed that the alloys of Sn-3.5Ag, Sn-3.5Ag-1Bi and Sn-3.5Ag-3Bi are composed of two phases; Ag{sub 3}Sn IMC embedded in Sn matrix phase, which indicated that the solubility of Bi phase in Sn-matrix was extended to 3 % as a result of rapid solidification. Bi precipitation in Sn matrix was only observed in Sn-3.5Ag-5Bi and Sn-3.5Ag-10Bi alloys. Also, addition of Bi decreased continuously the melting point of the eutectic Sn-3.5Ag alloy to 202.6 C at 10 % Bi. Vickers hardness of Sn-3.5Ag rapidly solidified alloy increased with increasing Bi content up to 3 % due to supersaturated solid solution strengthening hardening mechanism of Bi phase in Sn matrix, while the alloys contain 5 and 10 % Bi exhibited lower values of Vickers hardness. The lower values can be attributed to the precipitation of Bi as a secondary phase which may form strained regions due to the embrittlement of Bi atom. In addition, the effect of Bi addition on the micro-creep behavior of Sn-3.5Ag alloy as well as the creep rate have been described and has been calculated at room temperature. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Hardness and microstructure of Al-10.0 wt% Zn-4.0 wt% Mg alloy

International Nuclear Information System (INIS)

Iqbal, M.; Shaikh, M.A.; Ahmad, W.; Ali, K.L.

1996-01-01

Al-Zn-Mg alloys are widely used in industries as these have excellent physical and mechanical properties. However some aspects of the effect of heat treatment on these alloys are not yet clear. In order to understand the precipitation phenomena in these alloys, microstructure of a locally prepared alloy Al-10.0 wt% Zn-4.0 wt% Mg heat treated under different conditions has been examined in scanning electron microscope/electron probe micro analyser. Precipitates MgZn/sub 2/, MgZn/sub 4/ and Mg/sub 2/Zn/sub 11/ have been observed and these are caused by heat treatment. Correlation between these precipitates and Vickers's hardness has also been studied. In the present paper results of this investigation have been presented and discussed. (author)

Microstructure and Hardness of Cold Work Vanadis 6 Steel after Subzero Treatment at −140°C

Directory of Open Access Journals (Sweden)

Juraj Ďurica

2018-01-01

Full Text Available The microstructure, phase constitution, and hardness of Cr-V ledeburitic tool steel Vanadis 6 subjected to subzero treatment at −140°C and for different soaking times have been investigated. The light microscopy, scanning electron microscopy, and X-ray diffraction have been used for microstructural investigations. The hardness has been evaluated by the Vickers method. The obtained results assist to draw that subzero treatment reduces the retained austenite amount and increases the population density of carbides, compared to conventional heat treatment. The extent of decrease in the retained austenite amount makes around 85%, and the increase in population density of small globular carbides was approximately fivefold. High compressive stresses were identified in the retained austenite, and their values follow the increase in carbide count. This makes a serious support to the theory explaining the formation of “extra” carbides as a by-product of more complete martensitic transformation. As a result of the mentioned microstructural changes, the material hardness increased from 875 ± 16 HV 10 up to 954.6 ± 14 HV 10 for conventionally quenched and SZT steels, respectively.

Microhardness of the YbxY1-xInCu4 alloy system: the of electronic structure on hardness

International Nuclear Information System (INIS)

Ocko, M; Sarrao, J L; Stubicar, N; Aviani, I; Simek, Z; Stubicar, M

2003-01-01

We show that the Vickers microhardness, measured on flux grown single crystals of the Yb x Y 1-x InCu 4 alloy system, although sample dependent, exhibits clear concentration dependence; it increases with decreasing x. Such a dependence is not expected because the cubic lattice parameter increases with decreasing x and one expects then a decrease of hardness with decreasing x. Also, such a concentration dependence is in accordance with neither the Mott-Nabarro theory nor other known experimental results. We ascribe the observed dependence to the change of the electronic structure of the Yb x Y 1-x InCu 4 alloy system with x

Investigation of stand-off distance effect on structure, adhesion and hardness of copper coatings obtained by the APS technique

Science.gov (United States)

Masoumeh, Goudarzi; Shahrooz, Saviz; Mahmood, Ghoranneviss; Ahmad, Salar Elahi

2018-03-01

The outbreak of the disease and infection in the hospital environment and medical equipment is one of the concerns of modern life. One of the effective ways for preventing and reducing the complications of infections is modification of the surface. Here, the handmade atmospheric plasma spray system is used for accumulating copper as an antibacterial agent on the 316L stainless steel substrate, which applies to hospital environment and medical equipment. As a durable coating with proper adhesion is needed on the substrate, the effect of stand-off distance (SOD) which is an important parameter of the spray on the microstructure, the hardness and adhesion of the copper coating on the 316L stainless steel were investigated. The structure and phase composition of copper depositions were investigated using scanning electron microscopy and X-ray diffraction. The adhesion and hardness of depositions are evidenced using the cross cut tester and Vickers hardness tester, respectively. The findings confirm that the voids in the coatings increase with increasing SOD, which leads to decreasing the hardness of coatings and also the adhesion strength between depositions and substrate. In addition, by increasing the SOD, the oxygen content and the size of grains in the lamellae (fine structure) of coatings also increase.

Synergistic methods for the production of high-strength and low-cost boron carbide

Science.gov (United States)

Wiley, Charles Schenck

2011-12-01

sintering behavior were performed via high-temperature dilatometry in order to measure the in-situ sample contraction and thereby measure the influence of the additives and their amounts on the overall densification rate. Additionally, broad composition and sintering/post-HIPing studies followed by characterization and mechanical testing elucidated the effects of these additives on sample densification, microstructure de- velopment, and mechanical properties such as Vickers hardness and microindentation fracture toughness. Based upon this research, a process has been developed for the sintering of boron carbide that yielded end products with high relative densities (i.e., 100%, or theoretical density), microstructures with a fine (˜2-3 mum) grain size, and high Vickers microindentation hardness values. In addition to possessing these improved physical properties, the costs of producing this material were substantially lower (by a factor of 5 or more) than recently patented work on the pressureless sintering and post-HIPing of phase-pure boron carbide powder. This recently patented work developed out of our laboratory utilized an optimized powder distribution and yielded samples with high relative densities and high hardness values. The current work employed the use of titanium and carbon additives in specific ratios to activate the sintering of boron carbide powder possessing an approximately mono-modal particle size distribution. Upon heating to high temperatures, these additives produced fine-scale TiB2 and graphite inclusions that served to hinder grain growth and substantially improve overall sintered and post-HIPed densities when added in sufficient concentrations. The fine boron carbide grain size manifested as a result of these second phase inclusions caused a substantial increase in hardness; the highest hardness specimen yielded a hardness value (2884.5 kg/mm2) approaching that of phase-pure and theoretically-dense boron carbide (2939 kg/mm2). Additionally, the

Microstructural and hardness behavior of graphene-nanoplatelets/aluminum composites synthesized by mechanical alloying

International Nuclear Information System (INIS)

Pérez-Bustamante, R.; Bolaños-Morales, D.; Bonilla-Martínez, J.; Estrada-Guel, I.; Martínez-Sánchez, R.

2014-01-01

Highlights: • Pure aluminum was reinforced with graphene-platelets by using mechanical milling. • The composites were studied after sintering condition. • Milling time and graphene-platelet enhance the mechanical behavior of the composites. - Abstract: Graphene can be considered as an ideal reinforcement for the production of composites due to its outstanding mechanical properties. These characteristics offer an increased opportunity for their study in the production of metal matrix composites (MMCs). In this research, the studied composites were produced by mechanical alloying (MA). The employed milling times were of 1, 3 and 5 h. GNPs were added in 0.25, 0.50 and 1.0 wt% into an aluminum powder matrix. Milled powders were cold consolidated and subsequently sintered. Composites were microstructurally characterized with Raman spectroscopy and electron microscopy and X-ray diffraction. The hardness behavior in composites was evaluated with a Vickers micro-hardness test. A homogeneous dispersion of graphene during MA and the proper selection of sintering conditions were considered to produce optimized composites. The obtained results with electron microscopy indicate a homogeneous dispersion of GNPs into the aluminum matrix. Analyses showed GNPs edges where the structure of the graphene layers conserved after MA is observed

Effect of Coil Current on the Properties of Hydrogenated DLC Coatings Fabricated by Filtered Cathodic Vacuum Arc Technique

Science.gov (United States)

Liao, Bin; Ouyang, Xiaoping; Zhang, Xu; Wu, Xianying; Bian, Baoan; Ying, Minju; Jianwu, Liu

2018-01-01

We successfully prepared hydrogenated DLC (a-C:H) with a thickness higher than 25 μm on stainless steel using a filtered cathode vacuum arc (FCVA) technique. The structural and mechanical properties of DLC were systematically analyzed using different methods such as x-ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, Vickers hardness, nanohardness, and friction and wear tests. The effect of coil current on the arc voltage, ion current, and mechanical properties of resultant films was systematically investigated. The novelty of this study is the fabrication of DLC with Vickers hardness higher than 1500 HV, in the meanwhile with the thickness higher than 30 μm through varying the coil current with FCVA technique. The results indicated that the ion current, deposition rate, friction coefficient, and Vickers hardness of DLC were significantly affected by the magnetic field inside the filtered duct.

Static and fatigue mechanical behavior of three dental CAD/CAM ceramics.

Science.gov (United States)

Homaei, Ehsan; Farhangdoost, Khalil; Tsoi, James Kit Hon; Matinlinna, Jukka Pekka; Pow, Edmond Ho Nang

2016-06-01

The aim of this study was to measure the mechanical properties and fatigue behavior of three contemporary used dental ceramics, zirconia Cercon(®) (ZC), lithium disilicate e.max(®) CAD (LD), and polymer-infiltrated ceramic Enamic(®) (PIC). Flexural strength of each CAD/CAM ceramic was measured by three point bending (n=15) followed by Weibull analysis. Elastic modulus was calculated from the load-displacement curve. For cyclic fatigue loading, sinusoidal loading with a frequency of 8Hz with minimum load 3N were applied to these ceramics (n=24) using three point bending from 10(3) to 10(6) cycles. Fatigue limits of these ceramics were predicted with S-N fatigue diagram. Fracture toughness and Vickers hardness of the ceramics were measured respectively by single edge V-notch beam (SEVNB) and microindentation (Hv 0.2) methods. Chemical compositions of the materials׳ surfaces were analyzed by EDS, and microstructural analysis was conducted on the fracture surfaces by SEM. One-way ANOVA was performed and the level of significance was set at 0.05 to analyze the numerical results. The mean flexural strength of ZC, LD, and PIC was respectively 886.9, 356.7, and 135.8MPa. However, the highest Weibull modulus belonged to PIC with 19.7 and the lowest was found in LD with 7.0. The fatigue limit of maximum load for one million cycles of ZC, LD, and PIC was estimated to be 500.1, 168.4, and 73.8GPa. The mean fracture toughness of ZC, LD, and PIC was found to be respectively 6.6, 2.8, and 1.4MPam(1/2), while the mean Vickers hardness was 1641.7, 676.7, and 261.7Hv. Fracture surfaces followed fatigue loading appeared to be smoother than that after monotonic loading. Mechanical properties of ZC were substantially superior to the two other tested ceramics, but the scattering of data was the least in PIC. The fatigue limit was found to be approximately half of the mean flexural strength for all tested ceramics. Copyright © 2016 Elsevier Ltd. All rights reserved.

Influence of light-curing units and restorative materials on the micro hardness of resin cements

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Kuguimiya Rosiane

2010-01-01

Full Text Available Aim: The aim of this study was to evaluate the effect of indirect restorative materials (IRMs and light-curing units (LCUs on the micro hardness of dual-cured resin cement. Materials and Methods: A total of 36 cylindrical samples (2 mm thick were prepared with dual-cured resin cement (Relyx ARC photo-activated with either a QTH (Optilight Plus for 40s or a LED (Radii light-curing unit for 65s. Photo-activation was performed through the 2-mm- thick IRMs and the samples were divided into six groups (n=6 according to the combination of veneering materials (without, ceramic and indirect resin and LCUs (QTH and LED. In the control group, the samples were light-cured with a QTH unit without the interposition of any restorative material. Vickers micro hardness test was performed on the top and bottom surfaces of each sample (load of 50 g for 15 secs. The data were statistically analyzed using a three-way ANOVA followed by Tukey x s post-hoc test ( P < 0.05. Results: There were no statistically significant differences on the top surface between the light curing-units ( P > 0.05; however, the LED provided greater hardness on the bottom surface when a ceramic material was used ( P < 0.05. The mean hardness in photo-activated samples, in which there was no interposition of indirect materials, was significantly greater ( P < 0.01. Conclusions: It may be concluded that the interposition of the restorative material decreased the micro hardness in the deeper cement layer. Such decrease, however, was lower when the ceramic was interposed and the cement light-cured with LED.

Diamond-like carbon coatings enhance the hardness and resilience of bearing surfaces for use in joint arthroplasty.

Science.gov (United States)

Roy, M E; Whiteside, L A; Xu, J; Katerberg, B J

2010-04-01

The purpose of this study was to evaluate the potential of a hard diamond-like carbon (DLC) coating to enhance the hardness and resilience of a bearing surface in joint replacement. The greater hardness of a magnesium-stabilized zirconium (Mg-PSZ) substrate was expected to provide a harder coating-substrate composite microhardness than the cobalt-chromium alloy (CoCr) also used in arthroplasty. Three femoral heads of each type (CoCr, Mg-PSZ, DLC-CoCr and DLC-Mg-PSZ) were examined. Baseline (non-coated) and composite coating/substrate hardness was measured by Vickers microhardness tests, while nanoindentation tests measured the hardness and elastic modulus of the DLC coating independent of the Mg-PSZ and CoCr substrates. Non-coated Mg-PSZ heads were considerably harder than non-coated CoCr heads, while DLC coating greatly increased the microhardness of the CoCr and Mg-PSZ substrates. On the nanoscale the non-coated heads were much harder than on the microscale, with CoCr exhibiting twice as much plastic deformation as Mg-PSZ. The mechanical properties of the DLC coatings were not significantly different for both the CoCr and Mg-PSZ substrates, producing similar moduli of resilience and plastic resistance ratios. DLC coatings greatly increased hardness on both the micro and nano levels and significantly improved resilience and resistance to plastic deformation compared with non-coated heads. Because Mg-PSZ allows less plastic deformation than CoCr and provides a greater composite microhardness, DLC-Mg-PSZ will likely be more durable for use as a bearing surface in vivo. Copyright 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

First-principle calculations on the structural and electronic properties of hard C11N4

International Nuclear Information System (INIS)

Li, Dongxu; Shi, Jiancheng; Lai, Mengling; Li, Rongkai; Yu, Dongli

2014-01-01

A graphite-like C 11 N 4 model was built by stacking graphene and a C 3 N 4 triazine layer and simulated by first principle calculations, which transfers to a diamond-like structure under high pressure. The structural, mechanical, and electronic properties of both materials were calculated. The elastic constants of both materials satisfy the Born-criterion. Furthermore, no imaginary frequencies were observed in phonon calculations. The diamond-like C 11 N 4 is semiconducting and consists of polyhedral and hollow C–N cages. The Vickers hardness of diamond-like C 11 N 4 was calculated to be 58 GPa. The phase transformation from graphite-like to diamond-like C 11 N 4 is proposed to occur at approximately 27.2 GPa based on the pressure-dependent enthalpy

Effect of storage in water and thermocycling on hardness and roughness of resin materials for temporary restorations

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Jerusa Cleci de Oliveira

2010-09-01

Full Text Available PURPOSE: This study evaluated the effect of storage in water and thermocycling on hardness and roughness of resin materials for temporary restorations. MATERIAL AND METHODS: Three acrylic resins (Dencor-De, Duralay-Du, and Vipi Cor-VC were selected and one composite resin (Opallis-Op was used as a parameter for comparison. The materials were prepared according to the manufacturers' instructions and were placed in stainless steel moulds (20 mm in diameter and 5 mm thick. Thirty samples of each resin were made and divided into three groups (n = 10 according to the moment of Vickers hardness (VHN and roughness (Ra analyses: C (control group: immediately after specimen preparation; Sw: after storage in distilled water at 37 °C for 24 hours; Tc: after thermocycling (3000 cycles; 5-55 °C, 30 seconds dwell time. Data were submitted to 2-way ANOVA followed by Tukey's test (α = 0.05. RESULTS: Op resin had higher surface hardness values (p 0.05 in roughness among materials (De = 0.31 ± 0.07; Du = 0.51 ± 0.20; VC = 0.41 ± 0.15; Op = 0.42 ± 0.18. Storage in water did not change hardness and roughness of the tested materials (p > 0.05. There was a significant increase in roughness after thermocycling (p < 0.05, except for material Du, which showed no significant change in roughness in any evaluated period (p = 0.99. CONCLUSION: Thermocycling increased the roughness in most tested materials without affecting hardness, while storage in water had no significant effect in the evaluated properties.

Effects of a laser surface processing induced heat-affected zone on the fatigue behavior of AISI 4340 steel

International Nuclear Information System (INIS)

McDaniels, R.L.; White, S.A.; Liaw, K.; Chen, L.; McCay, M.H.; Liaw, P.K.

2008-01-01

The effects of the heat-affected zone (HAZ) in AISI 4340 steel created by laser-surface alloying (LSA) on high-cycle fatigue behavior have been investigated. This research was performed by producing several lots of laser-processed AISI 4340 steel using different laser processing parameters, and then subjecting the samples to high-cycle fatigue and Knoop microindentation hardness studies. Samples of tested material from each lot were examined using scanning-electron microscopy (SEM) in order to establish the effects of laser processing on the microstructure of the fatigue-tested AISI 4340 steel. When these three techniques, microindentation hardness testing, high-cycle fatigue testing, and SEM, are combined, a mechanistic understanding of the effect of the HAZ on the fatigue behavior of this alloy might be gained. It was found that the HAZ did not appear to have an adverse effect on the high-cycle fatigue behavior of LSA-processed AISI 4340 steel

High hardness-high toughness WC-20Co nanocomposites: Effect of VC variation and sintering temperature

International Nuclear Information System (INIS)

Kumar, Devender; Singh, K.

2016-01-01

WC-Co nanocomposites with variable VC content are synthesized by liquid phase sintering at two different temperatures. The as synthesized samples are characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and optical microscope. The mechanical properties are obtained by Vickers indentation method. The high content of VC, lead to high porosity when sintering temperature is increased from 1350 to 1400 °C. The relative density of all the samples is more than 95%. Microstructure reveals that agglomeration of W-Co-C and V-W-C increases at 1400 °C, which generates layered interfaces in radial direction and hence the material inhomogeneity. XRD pattern shows that the formation of η phase increases at 1400 °C, which is responsible to decrease the fracture toughness of the present samples. The average particle size of 102 nm, highest hardness of 1870.6 kgf/mm"2 with fracture toughness of 14.4 MN/mm"3"/"2 is observed in sample having 7.5 wt% VC, sintered at 1350 °C for one minute. This combination shows the highest hardness and reasonably high toughness as compared to conventionally sintered materials reported so far.

Evaluation of mechanical hardness and fracture toughness of Co and Al co-doped ZnO

International Nuclear Information System (INIS)

Siddheswaran, R.; Mangalaraja, R.V.; Avila, Ricardo E.; Manikandan, D.; Esther Jeyanthi, C.; Ananthakumar, S.

2012-01-01

Combustion synthesized nanocrystalline Co and Al co-doped ZnO powders [(Zn 1−x−y Co x Al y O; x=0.04, 0.03, 0.02; y=0.01, 0.02, 0.03)] were fabricated into cylindrical discs by uni-axial pressing and sintered intentionally at 1000 °C for 2 h to assess the mechanical performance. The crystallinity of the pure and doped ZnO was confirmed by X-ray diffraction analysis. The microstructures of the sintered samples were investigated by scanning electron microscopy (SEM) to examine the density, porosity, grain size and its distribution. Grains of 0.5–3 μm were observed for the samples sintered at 1000 °C. The mechanical properties such as micro-hardness, fracture toughness and strain hardening co-efficient were investigated by the Vickers indentation method. It was found that the crack mode observed during the indentation on the samples belongs to median cracks under a load of 19.6 N. Also, the hardness was enhanced with increasing mol% of Co, while the trend was reversed with the increase of Al content. In addition, the strain hardening coefficient and fracture toughness were calculated using the indentation data.

The effect of Coca-Cola and fruit juices on the surface hardness of glass-ionomers and 'compomers'.

Science.gov (United States)

Aliping-McKenzie, M; Linden, R W A; Nicholson, J W

2004-11-01

The interaction of tooth-coloured dental restorative materials (a conventional glass-ionomer, two resin-modified glass-ionomers and two compomers) with acidic beverages has been studied with the aim of investigating how long-term contact affects solution pH and specimen surface hardness. For each material (ChemFil Superior, ChemFlex, Vitremer Core Build-Up/Restorative, Fuji II LC, Dyract AP and F2000) disc-shaped specimens were prepared and stored in sets of six in the following storage media: 0.9% NaCl (control), Coca-Cola, apple juice and orange juice. After time intervals of 1 day, 1 week, 1 month, 3 months, 4 months, 6 months and 1 year, solution pH and Vickers Hardness Number were determined for each individual specimen. Differences were analysed by anova followed by Student-Newman-Keuls post hoc analysis. All materials were found to reduce the pH of the 0.9% NaCl, but to increase the pH of the acidic beverages. The conventional glass-ionomers dissolved completely in apple juice and orange juice, but survived in Coca-Cola, albeit with a significantly reduced hardness after 1 year. The other materials survived in apple juice and orange juice, but showed greater reductions in surface hardness in these beverages than in Coca-Cola. Fruit juices were thus shown to pose a greater erosive threat to tooth coloured materials than Coca-Cola, a finding which is similar to those concerning dentine and enamel towards these drinks.

A new non-destructive method for estimating the remanent life of a turbine rotor steel by reversible magnetic permeability

International Nuclear Information System (INIS)

Ryu, K.S.; Nahm, S.H.; Park, J.S.; Yu, K.M.; Kim, Y.B.; Son, D.

2002-01-01

We present a new magnetic and non-destructive procedure to evaluate the remanent life of 1Cr-1Mo-0.25V steel using the value of reversible magnetic permeability. The method is based on the existence of reversible magnetic permeability in the differential magnetization around the coercive force. The measurement principle is based on the foundation harmonics voltage induced in a coil using a lock-in amplifier tuned to a frequency of the exciting one. Results obtained for reversible magnetic permeability and Vickers hardness on the aged sample show that the peak interval of reversible magnetic permeability (PIRMP) and Vickers hardness decreases as aging time increases. A softening curve is obtained from the correlation between Vickers hardness and the PIRMP. This curve can be used as a non-destructive method to evaluate the remanent life of 1Cr-1Mo-0.25V steel

Use of variations in unit cell length, reflectance and hardness for determining the origin of Fe disulphides in sedimentary rocks

Science.gov (United States)

Dill, H. G.; Eberhard, E.; Hartmann, B.

1997-01-01

Fe disulphides are common opaque accessories in sedimentary rocks. Both marcasite and pyrite may shed some light on the depositional environment and help determine the diagenesis of their host rocks. Quantitative ore microscopy (reflectance measurements, Vickers hardness numbers) and X-ray diffraction methods, supplemented with scanning electron microscopy and chemical analyses, were applied to pyrite (and some marcasite) hosted by sedimentary rocks spanning the interval from the Devonian to the Pliocene, and formed in various marine and continental environments. Quantitative ore microscopy of pyrites of sedimentary origin does not seem to be an efficient tool for analyzing the environment owing to the inhomogeneous nature of sulphide aggregates when viewed under the ore microscope, and the variable amounts of minor elements (e.g., As, Ni, and Co) that control the reflectance values (RV) and Vickers hardness numbers (VHN) of the host sulphides. However, such parameters as crystal habit and unit cell length of pyrite, which correlate with FeS x, are useful for environmental analysis. The redox conditions and the presence of organic remains during formation are the main factors determining these crystallographic parameters. Differences in these parameters from those of pure, ideal FeS 2 can be related to substitution of, e.g., wustite in the pyrite lattice, reflecting moderate oxidation (i.e. in the microenvironment). As far as crystal habit and length of the cell edge are concerned, late stage diagenesis is obviously less important than the microenvironment attending initial formation. The environment of deposition (i.e. the macroenvironment) of pyrite-bearing rocks has no influence on the crystal morphology or the length of the unit cell of Fe disulphide. X-ray diffraction measurements demonstrate that this method provides useful evidence on the microenvironment of sulphide precipitation around a single, equant pyrite, as well as around pyritized fossils.

Effect of conventional and sugar free pediatric syrup formulations on primary tooth enamel hardness: An in vitro study

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Gaurao Vasant Mali

2015-01-01

Full Text Available Objectives: To assess and compare the effect of conventional and sugar free pediatric syrup formulations on primary tooth enamel hardness over a period of 14 days. Materials and Methods: An in vitro study was done on 40 noncarious deciduous teeth. 10 teeth in each group were dipped in 4 pediatric medicinal syrups (1 sugarfree and 3 conventional for 1 min thrice daily for 14 days and the enamel surface micro hardness was checked at baseline, 7 th day and 14 th day by Vickers hardness testing machine. The pH, titratable acidity and buffering capacity of the syrups were assessed. Results: The pH of syrups were above critical pH for demineralization of the tooth but tiratable acidity and buffering capacity differed. ANOVA test indicated that the reduction in mean micro hardness was maximum in Group D (Conventional Analgesic syrup and least in Group A (Sugarfree cough syrup on 7 th and 14 th day. On intergroup comparison there was no difference (P > 0.05 in micro hardness between Group B (Conventional Cough syrup and Group C (Conventional Antibiotic. However, highly significant (P < 0.01 difference between the either pair of Group B with Group D, and Group C with Group D on 14 th day. The percentage reduction in micro hardness on 14 th day was maximum for Group D (24.4 ± 2.2 and minimum for Group A (14.0 ± 1.3 which was statistically significant (P < 0.01. Conclusion: Sugar free pediatric medicines can be effective in reducing dental erosion and efforts should be made to incorporate sugar substitutes in formulation of pediatric medicines.

Evaluation of the surface hardness of composite resins before and after polishing at different times Avaliação da dureza superficial de resinas compostas antes e após o polimento em diferentes tempos

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Michelle Alexandra Chinelatti

2006-06-01

Full Text Available PURPOSE: The aim of this study was to evaluate the surface hardness of six composite resins: Revolution, Natural Flow, Fill Magic Flow, Flow-it! (flowables, Silux Plus (microfilled and Z100 (minifilled before and after polishing at different times. MATERIALS AND METHODS: For this purpose, 240 specimens (5mm diameter, 1.4mm high were prepared. Vickers hardness was determined before and after polishing at different times: immediately, 24h, 7 and 21 days after preparation of the samples. Statistical analysis was performed by ANOVA and Tukey test. RESULTS: There was no difference in the hardness of flowable resins, which had lower hardness than the minifilled resin. The minifilled resin showed the highest surface hardness as compared to the other materials (pPROPOSIÇÃO: O objetivo deste estudo foi avaliar a dureza superficial de seis resinas compostas - Revolution, Natural Flow, Fill Magic Flow, Flow-it! (flowables, Silux Plus (micropartículas e Z100 (híbrida - antes e após o polimento realizado em diferentes tempos. MATERIAL E MÉTODO: Foram confeccionados 240 corpos-de-prova circulares (5mm de diâmetro e 1,4mm de altura. A dureza Vickers foi obtida antes e após o polimento realizado em diferentes tempos: imediatamente, 24 horas, 7 dias e 21 dias após a confecção do corpo-de-prova. Os dados foram analisados estatisticamente por meio da ANOVA e do Teste de Tukey. RESULTADOS: Não houve diferença entre as resinas compostas flowable, as quais apresentaram os menores valores de dureza. A resina composta híbrida demonstrou os melhores resultados. Todos os materiais exibiram aumento de dureza após a realização do polimento, que foi mais evidente após 7 dias. CONCLUSÃO: Pôde-se concluir que, independente do tipo de resina composta, a dureza superficial foi consideravelmente maior quando o polimento foi realizado 1 semana após a confecção dos corpos-de-prova.

Correlation between yield stress and hardness of nickel–silicon–boron-based alloys by nanoindentation

International Nuclear Information System (INIS)

Şerban, Viorel-Aurel; Codrean, Cosmin; Vodă, Mircea; Chicot, Didier; Decoopman, Xavier

2014-01-01

Based on the relation proposed by Tabor in 1951, which connects the ultimate tensile strength and the yield stress of classical materials to the Brinell or Vickers hardness numbers by a simple factor of proportionality, we propose an extended analytical model for the determination of the yield stress of brittle materials using nanoindentation data. This model considers the nanoindentation hardness calculated from the projected actual contact area between the indenter and the material which is representative of the real mean pressure exerted by the indenter compared to classical hardness numbers. A coefficient is introduced in the model to integrate the extent of the elastic recovery of the indented material occurring after the withdrawal of the indenter. This is possible by using the criterion defined by the residual to maximum indenter displacements ratio, this criterion being already related to the deformation mode under indentation. Indeed, this criterion allows identifying the piling-up deformation observed for complete or fully plastic deformation materials or the sinking-in deformation for purely elastic materials. The proposed model thus allows a good estimation of the yield stress of brittle materials for which classical tensile tests are not applicable. The model is validated on a variety of amorphous nickel–silicon-based alloy ribbons, i.e., Ni 89 Si 9 B 2 , Ni 78 Si 9 B 13 and Ni 68 Fe 3 Cr 7 Si 8 B 14 on which both nanoindentation tests and tensile experiments have been performed

A correlation between micro- and nano-indentation on materials irradiated by high-energy heavy ions

Science.gov (United States)

Yang, Yitao; Zhang, Chonghong; Ding, Zhaonan; Su, Changhao; Yan, Tingxing; Song, Yin; Cheng, Yuguang

2018-01-01

Hardness testing is an efficient means of assessing the mechanical properties of materials due to the small sampling volume requirement. Previous studies have established the correlation between flow stress and Vickers hardness. However, the damage layer produced by ions irradiation with low energy is too thin to perform Vickers hardness test, which is usually measured by nano-indentation. Therefore, it is necessary to correlate the Vickers hardness and nano-hardness for the convenience of assessing mechanical properties of materials under irradiation. In this study, various materials (pure nickel, nickel base alloys and oxide dispersion strengthened steel) were irradiated with high-energy heavy ions to different damage levels. After irradiation, micro- and nano-indentation were performed to characterize the change in hardness. Due to indentation size effect (ISE), the hardness was dependent of load or depth. Therefore, Nix-Gao model was used to obtain the hardness without ISE (Hv0 and Hnano_0). The determined Hv0 was plotted as a function of the corresponding Hnano_0, then a good linear relation was found between Vickers hardness and nano-hardness, and a coefficient was determined to be 81.0 ± 10.5, namely, Hv 0 = 81.0Hnano _ 0 (Hv0 with unit of kgf/mm2, Hnano_0 with unit of GPa). This correlation was based on the data from various materials, therefore it was independent of materials. Based on the established correlation and nano-indentation results, the change fraction in yield stress of Inconel 718 and pure Ni with ion irradiation was compared with that with neutron irradiation. The data of Inconel 718 with heavy ion irradiation was in good agreement with the data with neutron irradiation, which was a good demonstration for the validation of the established correlation. However, a distinctive difference in change fraction of yield stress was seen for pure Ni under heavy ion irradiation and neutron irradiation, which was attributed to the difference in samples

Surface roughness and hardness of a composite resin: influence of finishing and polishing and immersion methods

Directory of Open Access Journals (Sweden)

Ana Luísa Botta Martins de Oliveira

2010-09-01

Full Text Available This study evaluated the finishing and polishing effect on the surface roughness and hardness of the Filtek Supreme XT, in fluoride solutions. Specimens were prepared (n = 140 with half of the samples finished and polished with Super-Snap® disks. The experimental groups were divided according to the presence or absence of finishing and polishing and immersion solutions (artificial saliva, sodium fluoride solution at 0.05% - manipulated, Fluordent Reach, Oral B, Fluorgard. The specimens remained immersed in artificial saliva for 24 hours and were then subjected to initial analysis (baseline of surface roughness and Vickers microhardness. Next, they were immersed in different fluoride solutions for 1 min/day, for 60 days. Afterwards, a new surface roughness and microhardness reading was conducted. The data were submitted to a two-way ANOVA and Tukey's test (5% significance level. For the comparison of mean roughness and hardness at baseline and after 60 days, the paired Student t test was used. The results showed that the surface roughness and microhardness of the Filtek Supreme XT were influenced by the finishing and polishing procedure, independently of the immersion methods.

Effect of Interlayer Coating Thickness on the Hardness and Adhesion for the Tungsten Carbide Cutting Tool

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Kamil Jawad Kadhim

2017-12-01

Full Text Available The thin film of the (Al,TiN coating is studied with the aid of two parameters: hardness and adhesion.  These parameters are very close to each other; however, in deposition field they could be interpreted differently.  Several coatings of (Al,TiN layers are developed on tungsten carbide insert using the standard commercial Al0.67Ti0.33 cathodes in cathodic arc plating system(PVD. The influence of coating layer thickness on the mechanical properties of the coatings was investigated via two parameters: hardness and adhesion are characterized by the Rockwell tester Vickers tester.  The measurements reveal that the highest hardness appears for the (Al,TiN thickness of 5.815 µm while the highest adhesion appears at a thickness of 3.089 µm.  At the opposite extreme, the lowest hardness appears at 2.717 µm and the lowest hardness at 5.815 µm. Overall, the (Al/Ti N coating of the thickness of 5.815 µm is controversial as it exhibits the highest hardness and the lowest adhesion. This result could be related to the effect of the formation of the micro-particle (MPs which has a direct effect on the hardness because these MPs appear mainly on the surface and their presence at the interface is very limited.  In addition, the creation of Ti buffering layer to reduce the delamination has its major effect on the adhesion but has no effect on the morphology of the surface.  For these two reasons and the effect of the bias voltage, the results presented in this paper might show slight differences with other published papers.  The composition of the (Al,TiN layer is characterized and, seemingly, it shows one important result which is showing that the ultimate composition of the (Al,TiN layer (Ti0.62Al0.38 is very close to the original target used in this study (Al0.67Ti0.33.

Hardness and Wear Resistance of TiC-Fe-Cr Locally Reinforcement Produced in Cast Steel

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Olejnik E.

2016-06-01

Full Text Available In order to increase wear resistance cast steel casting the TiC-Fe-Cr type composite zones were fabricated. These zones were obtained by means of in situ synthesis of substrates of the reaction TiC with a moderator of a chemical composition of white cast iron with nickel of the Ni-Hard type 4. The synthesis was carried out directly in the mould cavity. The moderator was applied to control the reactive infiltration occurring during the TiC synthesis. The microstructure of composite zones was investigated by electron scanning microscopy, using the backscattered electron mode. The structure of composite zones was verified by the X-ray diffraction method. The hardness of composite zones, cast steel base alloy and the reference samples such as white chromium cast iron with 14 % Cr and 20 % Cr, manganese cast steel 18 % Mn was measured by Vickers test. The wear resistance of the composite zone and the reference samples examined by ball-on-disc wear test. Dimensionally stable composite zones were obtained containing submicron sizes TiC particles uniformly distributed in the matrix. The macro and microstructure of the composite zone ensured three times hardness increase in comparison to the cast steel base alloy and one and a half times increase in comparison to the white chromium cast iron 20 % Cr. Finally ball-on-disc wear rate of the composite zone was five times lower than chromium white cast iron containing 20 % Cr.

Growth of Vanadium Carbide by Halide-Activated Pack Diffusion

DEFF Research Database (Denmark)

Fernandes, Frederico Augusto Pires; Christiansen, Thomas Lundin; Dahl, Kristian Vinter

The present work investigates growth of vanadium carbide (VC) layers by the pack diffusion method on a Vanadis 6 tool steel. The VC layers were produced by pack diffusion at 1000°C for 1, 4 and 16 hours. The VC layers were characterized with optical and electron microscopy, Vickers hardness tests...... and X-ray diffraction. Homogeneous VC mono-phase layers with Vickers hardness of more than 2400 HV were obtained. Hardening and tempering of the vanadized Vanadis 6 steel did not affect the VC layers....

Porosity-induced relaxation of strains in GaN layers studied by means of micro-indentation and optical spectroscopy

KAUST Repository

Najar, Adel

2012-05-04

We report the fabrication of porous GaNnanostructures using UV-assisted electroless etching of bulk GaN layer grown on c-plane sapphire substrate in a solution consisting of HF:CH3OH:H2O2. The morphology of the porous GaNnanostructures was characterized for different etching intervals using high resolution scanning electron microscopy. The geometry and size of resultant pores do not appear to be affected by the etching time; however, the pore density was augmented for longer etching time. Micro-indentation tests were carried out to quantify the indentation modulus for different porous GaNnanostructures. Our results reveal a relationship between the elastic properties and the porosity kinetics, i.e., a decrease of the elastic modulus was observed with increasing porosity. The photoluminescence(PL) and Raman measurements carried out at room temperature for the etched samples having a high degree of porosity revealed a strong enhancement in intensity. Also, the peak of the PL wavelength was shifted towards a lower energy. The high intensity of PL was correlated to an increase of scattered photons within the porous media and to the reduction of the dislocation density.

Effect of milling time and CNT concentration on hardness of CNT/Al2024 composites produced by mechanical alloying

International Nuclear Information System (INIS)

Pérez-Bustamante, R.; Pérez-Bustamante, F.; Estrada-Guel, I.; Licea-Jiménez, L.; Miki-Yoshida, M.; Martínez-Sánchez, R.

2013-01-01

Carbon nanotube/2024 aluminum alloy (CNT/Al 2024 ) composites were fabricated with a combination of mechanical alloying (MA) and powder metallurgy routes. Composites were microstructurally and mechanically evaluated at sintering condition. A homogeneous dispersion of CNTs in the Al matrix was observed by a field emission scanning electron microscopy. High-resolution transmission electron microscopy confirmed not only the presence of well dispersed CNTs but also needle-like shape aluminum carbide (Al 4 C 3 ) crystals in the Al matrix. The formation of Al 4 C 3 was suggested as the interaction between the outer shells of CNTs and the Al matrix during MA process in which crystallization took place after the sintering process. The mechanical behavior of composites was evaluated by Vickers microhardness measurements indicating a significant improvement in hardness as function of the CNT content. This improvement was associated to a homogeneous dispersion of CNTs and the presence of Al 4 C 3 in the aluminum alloy matrix. - Highlights: ► The 2024 aluminum alloy was reinforced by CNTs by mechanical alloying process. ► Composites were microstructural and mechanically evaluated after sintering condition. ► The greater the CNT concentration, the greater the hardness of the composites. ► Higher hardness in composites is achieved at 20 h of milling. ► The formation of Al 4 C 3 does not present a direct relationship with the milling time.

Mapping the structure, composition and mechanical properties of human teeth

International Nuclear Information System (INIS)

Low, I.M.; Duraman, N.; Mahmood, U.

2008-01-01

The structure-property relationship in human adult and baby teeth was characterised by grazing-incidence synchrotron radiation diffraction, optical and atomic-force microscopy, in addition to Vickers indentation. Similarities and differences between both types of teeth have been highlighted and discussed. Depth-profiling results indicated the existence of contrasting but distinct gradual changes in crystal disorder, phase abundance, crystallite size and hardness within the baby and adult enamel, thus confirming the graded nature of human teeth. When compared to the adult tooth, the baby enamel is softer, more prone to fracture, but has larger hydroxyapatite grains. Vickers hardness of the enamel was load-dependent but load-independent in the dentine. The use of a 'bonded-interface' technique revealed the nature and evolution of deformation-microfracture damage around and beneath Vickers contacts

Mapping the structure, composition and mechanical properties of human teeth

Energy Technology Data Exchange (ETDEWEB)

Low, I.M. [Materials Research Group, Department of Applied Physics, Curtin University of Technology, Perth, WA 6845 (Australia)], E-mail: j.low@curtin.edu.au; Duraman, N.; Mahmood, U. [Materials Research Group, Department of Applied Physics, Curtin University of Technology, Perth, WA 6845 (Australia)

2008-03-10

The structure-property relationship in human adult and baby teeth was characterised by grazing-incidence synchrotron radiation diffraction, optical and atomic-force microscopy, in addition to Vickers indentation. Similarities and differences between both types of teeth have been highlighted and discussed. Depth-profiling results indicated the existence of contrasting but distinct gradual changes in crystal disorder, phase abundance, crystallite size and hardness within the baby and adult enamel, thus confirming the graded nature of human teeth. When compared to the adult tooth, the baby enamel is softer, more prone to fracture, but has larger hydroxyapatite grains. Vickers hardness of the enamel was load-dependent but load-independent in the dentine. The use of a 'bonded-interface' technique revealed the nature and evolution of deformation-microfracture damage around and beneath Vickers contacts.

Effects of /sup 60/Co gamma radiation damage and heat treatment on the electro-mechanical properties of some related lithium alumino-borosilicate glasses

Energy Technology Data Exchange (ETDEWEB)

Abou Sekkina, M.M.; Gohar, I.A.; Megahed, A.A. (Al-Azhar Univ., Tanta (Egypt). Faculty of Science; Cairo Univ., El Mansura (Egypt). Faculty of Science)

1985-01-01

Various samples of pure lithium alumino-borosilicate glasses have been prepared and annealed. Data have been taken on the temperature dependence of DC electrical conductivity and the activation energy for conduction was evaluated in each case. Vickers hardness data have also been obtained as a function of tempering temperature and time for all glass compositions. Co-ordinated explanations of the DC conductivity and Vickers hardness induced by ionizing radiation are put forward and the activation energy for the process of carrier liberation are evaluated for the first time.

Effect of Mo concentration and aging time on the magnetic and mechanical hardness of Fe-xMo-5Ni-0.05C alloys (x = 5, 8, 11 and 15 wt. (%

Directory of Open Access Journals (Sweden)

Mauro Carlos Lopes Souza

2009-01-01

Full Text Available Changes to the microestructure during thermal aging treatment at 610 ºC in Fe-xMo-5Ni-0.05C alloys were studied for different aging times with different Mo concentrations. The heat treatment at 610 ºC induces carbide precipitation into the metallic matrix near Fe2Mo phase. The X-ray diffraction studies revealed a more intense precipitation of α-FeMo, Fe3Mo, R(Fe63Mo37 phases and MoC, Fe2MoC carbides for the alloys containing 15 and 11% Mo, respectively. This work shows that hardness and coercive force changes are function of the molybdenum content and aging time variation. Vickers hardness and coercive force both increase with the increase of molybdenum content and reach maximum values at 4 and 1h of aging, respectively.

Work Hard / Play Hard

OpenAIRE

Burrows, J.; Johnson, V.; Henckel, D.

2016-01-01

Work Hard / Play Hard was a participatory performance/workshop or CPD experience hosted by interdisciplinary arts atelier WeAreCodeX, in association with AntiUniversity.org. As a socially/economically engaged arts practice, Work Hard / Play Hard challenged employees/players to get playful, or go to work. 'The game changes you, you never change the game'. Employee PLAYER A 'The faster the better.' Employer PLAYER B

One-pot synthesis of hydroxyapatite–silica nanopowder composite ...

Indian Academy of Sciences (India)

(GIC) and Vickers hardness was evaluated. Results shown that the ... property might lead to extend the clinical indications, especially in stress bearing areas. Keywords. Hydroxyapatite–silica nanopowder; sol–gel technique; glass ionomer cement; hardness. 1. ..... A large hardness means greater resistance to plastic defor-.

Effect of mechanical properties of fillers on the grindability of composite resin adhesives.

Science.gov (United States)

Iijima, Masahiro; Muguruma, Takeshi; Brantley, William A; Yuasa, Toshihiro; Uechi, Jun; Mizoguchi, Itaru

2010-10-01

The purpose of this study was to investigate the effect of filler properties on the grindability of composite resin adhesives. Six composite resin products were selected: Transbond XT (3M Unitek, Monrovia, Calif), Transbond Plus (3M Unitek), Enlight (Ormco, Glendora, Calif), Kurasper F (Kuraray Medical, Tokyo, Japan), Beauty Ortho Bond (Shofu, Kyoto, Japan), and Beauty Ortho Bond Salivatect (Shofu). Compositions and weight fractions of fillers were determined by x-ray fluorescence analysis and ash test, respectively. The polished surface of each resin specimen was examined with a scanning electron microscope. Vickers hardness of plate specimens (15 × 10 × 3 mm) was measured, and nano-indentation was performed on large filler particles (>10 μm). Grindability for a low-speed tungsten-carbide bur was estimated. Data were compared with anlaysis of variance (ANOVA) and the Tukey multiple range test. Relationships among grindability, filler content, filler nano-indentation hardness (nano-hardness), filler elastic modulus, and Vickers hardness of the composite resins were investigated with the Pearson correlation coefficient test. Morphology and filler size of these adhesives showed great variations. The products could be divided into 2 groups, based on composition, which affected grindability. Vickers hardness of the adhesives did not correlate (r = 0.140) with filler nano-hardness, which showed a significant negative correlation (r = -0.664) with grindability. Filler nano-hardness greatly influences the grindability of composite resin adhesives. Copyright © 2010 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Effect of processing on fracture toughness of silicon carbide as determined by Vickers indentations

Science.gov (United States)

Dannels, Christine M.; Dutta, Sunil

1989-01-01

Several alpha-SiC materials were processed by hot isostatic pressing (HIPing) and by sintering an alpha-SiC powder containing boron and carbon. Several beta-SiC materials were processed by HIPing a beta-SiC powder with boron and carbon additions. The fracture toughnesses K(sub 1c) of these beta- and alpha-SiC materials were estimated from measurements of Vickers indentations. The three formulas used to estimate K(sub 1c) from the indentation fracture patterns resulted in three ranges of K(sub 1c) estimates. Furthermore, each formula measured the effects of processing differently. All three estimates indicated that fine-grained HIPed alpha-SiC has a higher K(sub 1c) than coarsed-grained sintered alpha-SiC. Hot isostatically pressed beta-SiC, which had an ultrafine grain structure, exhibited a K(sub 1c) comparable to that of HIPed alpha-SiC.

First-principle calculations on the structural and electronic properties of hard C{sub 11}N{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Li, Dongxu, E-mail: lidongxu@hqu.edu.cn [College of Materials Science and Engineering, Huaqiao University, Xiamen 361021 (China); Shi, Jiancheng; Lai, Mengling; Li, Rongkai [College of Materials Science and Engineering, Huaqiao University, Xiamen 361021 (China); Yu, Dongli [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China)

2014-09-15

A graphite-like C{sub 11}N{sub 4} model was built by stacking graphene and a C{sub 3}N{sub 4} triazine layer and simulated by first principle calculations, which transfers to a diamond-like structure under high pressure. The structural, mechanical, and electronic properties of both materials were calculated. The elastic constants of both materials satisfy the Born-criterion. Furthermore, no imaginary frequencies were observed in phonon calculations. The diamond-like C{sub 11}N{sub 4} is semiconducting and consists of polyhedral and hollow C–N cages. The Vickers hardness of diamond-like C{sub 11}N{sub 4} was calculated to be 58 GPa. The phase transformation from graphite-like to diamond-like C{sub 11}N{sub 4} is proposed to occur at approximately 27.2 GPa based on the pressure-dependent enthalpy.

The remineralization potential of cocoa (Theobroma cacao bean extract to increase the enamel micro hardness

Directory of Open Access Journals (Sweden)

Sulistianingsih Sulistianingsih

2017-08-01

Full Text Available Introduction: Remineralization is the process of returning mineral ions into a hydroxyapatite structure characterized by mineral deposition on the enamel surface. The presence of mineral deposition would affect the micro hardness of tooth enamel. The use of fluorine as remineralization agent with side effects such as fluorosis. Cocoa bean extract contains theobromin that can be used as an alternative remineralization ingredients. The objectives was to determine micro hardness email after remineralization using cocoa bean extract as natural material and to compare with fluorine use as synthetic material. Methods: Thirty-six maxillary first premolar tooth crown was cut and planted in the epoxy resin. Teeth were then immersed in demineralization solution at pH 4 for 6 hours. The sample were divided into 2 groups, 18 for the fluorine group and the remaining group of cocoa extract. Vickers microhardness test was used before treatment, after demineralized and after remineralization. Results: Enamel microhardness value before treatment in the fluorine group average value was 376.17 VHN and the cocoa extract group was 357.33 VHN. After demineralization in fluorine group was 268,13 VHN and cocoa extract group was 235,93 VHN. After remineralization in fluorine group was 321,08 VHN and cocoa extract group was 293,86 VHN. The results of the analysis showed that the level of micro hardness email after remineralization was not significantly different in two groups (p > 0.05. Conclusions: Cocoa extract is able to increase the microhardness of enamel so it can act as a substitution for fluorine remineralization.

Hardness and microstructural characterization of API 5L X70 steel pipes welded by HF/ERW process; Caracterizacao microestrutural e de dureza em tubos de aco API 5L X70 soldados pelo processo HF/ERW

Energy Technology Data Exchange (ETDEWEB)

Calcada, Mauricio Vieira; Voorwald, Herman Jacobus Cornelis; Nascimento, Marcelino Pereira do [UNESP, Guaratingueta, SP (Brazil). Faculdade de Engenharia

2010-07-01

The materials that stand in the manufacture of steel pipes are called API, that should have, high mechanical resistance, high corrosion resistance, high fatigue resistance, good weldability, and other properties. Thus, the purpose of this project was to evaluate the microstructure and hardness of welded joints by the HF/ERW process of API 5L X70 steel pipes. The microstructural analysis was performed using a surface finish with grit sizes from 220 to 25 {mu}m e polishing with diamond paste from 9 {mu}m to 0.05 {mu}m; the revelation was made with 3% Nital attack. The Vickers hardness was performed across the welded joint by 33 points to indentation. The results were: 80.5 {+-} 3.4% of ferrite and 19.5 {+-} 3.4% of perlite for microanalysis. As for hardness, the values were: 215.69 HV10 for weld line, 218.65 HV10 for ZTA and 218.95 HV10 for base metal. (author)

Near surface mechanical properties of optical single crystals and surface response to deterministic microgrinding

Science.gov (United States)

Randi, Joseph A., III

2005-12-01

This thesis makes use of microindentation, nanoindentation and nanoscratching methods to better understand the mechanical properties of single crystalline silicon, calcium fluoride, and magnesium fluoride. These properties are measured and are used to predict the material's response to material removal, specifically by grinding and polishing, which is a combination of elastic, plastic and fracture processes. The hardness anisotropy during Knoop microindentation, hardness from nanoindentation, and scratch morphology from nanoscratching are reported. This information is related to the surface microroughness from grinding. We show that mechanical property relationships that predict the surface roughness from lapping and deterministic microgrinding of optical glasses are applicable to single crystals. We show the range of hardness from some of the more common crystallographic faces. Magnesium fluoride, having a tetragonal structure, has 2-fold hardness anisotropy. Nanoindentation, as expected provides higher hardness than microindentation, but anisotropy is not observed. Nanoscratching provides the scratch profile during loading, after the load has been removed, and the coefficient of friction during the loading. Ductile and brittle mode scratching is present with brittle mode cracking being orientation specific. Subsurface damage (SSD) measurements are made using a novel process known as the MRF technique. Magnetorheological finishing is used to polish spots into the ground surface where SSD can be viewed. SSD is measured using an optical microscope and knowledge of the spot profile. This technique is calibrated with a previous technique and implemented to accurately measure SSD in single crystals. The data collected are compared to the surface microroughness of the ground surface, resulting in an upper bound relationship. The results indicate that SSD is always less than 1.4 times the peak-to-valley surface microroughness for single crystals regardless of the

Enhancement of the Wear Resistance and Microhardness of Aluminum Alloy by Nd:YaG Laser Treatment

Directory of Open Access Journals (Sweden)

Haitham T. Hussein

2014-01-01

Full Text Available Influence of laser treatment on mechanical properties, wear resistance, and Vickers hardness of aluminum alloy was studied. The specimens were treated by using Nd:YaG laser of energy 780 mj, wavelength 512 nm, and duration time 8 ns. The wear behavior of the specimens was studied for all specimens before and after treatment by Nd:YaG laser and the dry wear experiments were carried out by sing pinon-disc technique. The specimens were machined as a disk with diameter of 25 mm and circular groove in depth of 3 mm. All specimens were conducted by scanning electron microscopy (SEM, energy-dispersive X-ray florescence analysis (EDS, optical microscopy, and Vickers hardness. The results showed that the dry wear rate was decreased after laser hardening and increased Vickers hardness values by ratio of 2.4 : 1. The results showed that the values of wear rate for samples having circular grooves are less than samples without grooves after laser treatment.

Sintering Behavior of Spark Plasma Sintered SiC with Si-SiC Composite Nanoparticles Prepared by Thermal DC Plasma Process

Science.gov (United States)

Yu, Yeon-Tae; Naik, Gautam Kumar; Lim, Young-Bin; Yoon, Jeong-Mo

2017-11-01

The Si-coated SiC (Si-SiC) composite nanoparticle was prepared by non-transferred arc thermal plasma processing of solid-state synthesized SiC powder and was used as a sintering additive for SiC ceramic formation. Sintered SiC pellet was prepared by spark plasma sintering (SPS) process, and the effect of nano-sized Si-SiC composite particles on the sintering behavior of micron-sized SiC powder was investigated. The mixing ratio of Si-SiC composite nanoparticle to micron-sized SiC was optimized to 10 wt%. Vicker's hardness and relative density was increased with increasing sintering temperature and holding time. The relative density and Vicker's hardness was further increased by reaction bonding using additional activated carbon to the mixture of micron-sized SiC and nano-sized Si-SiC. The maximum relative density (97.1%) and Vicker's hardness (31.4 GPa) were recorded at 1800 °C sintering temperature for 1 min holding time, when 0.2 wt% additional activated carbon was added to the mixture of SiC/Si-SiC.

Hard electronics; Hard electronics

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-03-01

Hard material technologies were surveyed to establish the hard electronic technology which offers superior characteristics under hard operational or environmental conditions as compared with conventional Si devices. The following technologies were separately surveyed: (1) The device and integration technologies of wide gap hard semiconductors such as SiC, diamond and nitride, (2) The technology of hard semiconductor devices for vacuum micro- electronics technology, and (3) The technology of hard new material devices for oxides. The formation technology of oxide thin films made remarkable progress after discovery of oxide superconductor materials, resulting in development of an atomic layer growth method and mist deposition method. This leading research is expected to solve such issues difficult to be easily realized by current Si technology as high-power, high-frequency and low-loss devices in power electronics, high temperature-proof and radiation-proof devices in ultimate electronics, and high-speed and dense- integrated devices in information electronics. 432 refs., 136 figs., 15 tabs.

CORROSION IN ACIDIC BEVERAGES AND RECOVERY OF MICROHARDNESS OF HUMAN TEETH ENAMEL

Directory of Open Access Journals (Sweden)

Petra Gaalova

2016-05-01

Full Text Available We studied the influence of corrosion in acidic beverages (white wine, pH~3.5 on micromechanical properties of human teeth. Simultaneously, the effect of fluorine-containing mouthwash (pH~4.4 and of artificial saliva (pH~5.3 in terms of their protective action against corrosion, and the recovery of mechanical properties through fluoridation and re-calcification was studied. The influence of the solutions on Vickers hardness of dental enamel was monitored on the basis of results from the corrosion tests carried out under quasi-dynamic conditions. The tests were performed at the temperature corresponding to the temperature of human body (37°C. The measurements confirmed a significant deterioration of microhardness with prolonged exposure to white wine. The Vickers hardness decreased from 347 HV0.2 in un-corroded specimens to 186 HV0.2 in samples corroded for 60 minutes in white wine. A recovery of Vickers hardness was observed after 60 minutes exposition time in the fluoridation solution, with the increase from 186 to 372 HV0.2. Similar effect was observed in the artificial saliva solution, with observed hardness increase from 186 to 320 HV0.2. Healing of corrosion-induced defects by the action of both solutions was observed by SEM, and associated with observed increase of hardness

The effect of heat treatments applied to superstructure porcelain on the mechanical properties and microstructure of lithium disilicate glass ceramics.

Science.gov (United States)

Özdemir, Hatice; Özdoğan, Alper

2018-01-30

The aim of this study was to investigate that heat treatments with different numbers applied to superstructure porcelain whether effects microstructure and mechanical properties of lithium disilicate ceramic (LDC). Eighty disc-shaped specimens were fabricated from IPS e.max Press. Specimens were fired at heating values of porcelain in different numbers and divided four groups (n=5). Initial Vickers hardness were measured and X-ray diffraction (XRD) analysis was performed. Different surface treatment were applied and then Vickers hardness, surface roughness and environmental scanning electron microscopy (ESEM) analysis were performed. Data were analyzed with Varyans analysis and Tukey HSD test (α=0.05). Initial hardness among groups was no significant different (p>0.05), but hardness and surface roughness after surface treatments were significant different (pmicrostructure of LDC. Increasing firing numbers and surface treatments effect the microstructure of LDC.

Pengembangan Indentation Size Effect (ISE Dalam Penentuan Koefisien Pengerasan Regang Baja

Directory of Open Access Journals (Sweden)

I Nyoman Budiarsa

2016-07-01

Full Text Available Abstrak: Hubungan antara sifat material konstitutif dengan indentasi kekerasan (Hardness Indentation termasuk ISE (Indentation Size Effect telah dikembangkan dan dievaluasi dengan indentasi Vickers, hal Ini akan menjadi alat yang berguna dalam mengevaluasi kelayakan penggunaan nilai kekerasan dalam memprediksi parameter bahan konstitutif dengan mengacu pada syarat akurasi pada rentang semua potensi bahan. ISE dapat konsisten diukur dan dapat berpotensi dihubungkan dengan H/E rasio. Skala ISE dari sampel yang diuji menunjukkan pengulangan yang konsisten dan berhubungan kuat dengan sifat material secara signifikan. Hal Ini berpotensi memberikan set data eksperimen yang mencerminkan sifat material yang terkait dengan ketegangan gradien dan kerapatan dislokasi selama proses indentasi Konsep untuk menggunakan data ukuran indentasi Vickers telah dikembangkan untuk meningkatkan akurasi sifat invers pemodelan berdasarkan kekerasan menggunakan baja sebagai sistem bahan. Penelitian ini menunjukkan bahwa ada ISE signifikan dalam tes kekerasan Vickers dimana skala dan reliabilitas ISE dianalisis dengan fitting data mengikuti Power law and proportional resistance model Sebuah konsep baru menggunakan data ISE untuk memperkirakan Koefisien Pengerasan Regang (n nilai-nilai dari baja telah dievaluasi dan menunjukkan hasil yang baik untuk mempersempit kisaran sifat material yang diprediksi berdasarkan nilai-nilai kekerasan. . Kata kunci: ISE, H/E rasio, Koefisien Pengerasan Regang (n Abstract: The relationship between the constitutive material properties with Hardness indentation including ISE (indentation Size Effect has been developed and evaluated by Vickers indentation. This provided a useful tool in evaluating the feasibility of using of hardness value in predicting the constitutive material parameters with reference to the terms of accuracy in the all the potential materials range. ISE can be consistently measured and may potentially be associated with H

Mechanical properties of Al-Cu alloy-SiC composites

Science.gov (United States)

Anggara, B. S.; Handoko, E.; Soegijono, B.

2014-09-01

The synthesis of aluminum (Al) alloys, Al-Cu, from mixture 96.2 % Al and 3.8 % Cu has been prepared by melting process at a temperature of 1200°C. The adding 12.5 wt% up to 20 wt% of SiC on Al-Cu alloys samples has been investigated. The structure analyses were examined by X-Ray Diffractometer (XRD) and scanning electron microscope (SEM). Moreover, the morphology of Al-Cu alloys has been seen as structure in micrometer range. The hardness was measured by hardness Vickers method. According to the results, it can be assumed that the 15 wt% of SiC content is prefer content to get better quality of back to back hardness Vickers of Al-Cu alloys.

Mechanical properties of Al-Cu alloy-SiC composites

Energy Technology Data Exchange (ETDEWEB)

Anggara, B. S., E-mail: anggorobs1960@yahoo.com [Jurusan Fisika, FMIPA Universitas Negeri Jakarta, Indonesia 13220 and PPS Ilmu Material, Department Fisika, FMIPA, Universitas Indonesia (Indonesia); Handoko, E. [Jurusan Fisika, FMIPA Universitas Negeri Jakarta, 13220 (Indonesia); Soegijono, B. [PPS Ilmu Material, Department Fisika, FMIPA, Universitas Indonesia (Indonesia)

2014-09-25

The synthesis of aluminum (Al) alloys, Al-Cu, from mixture 96.2 % Al and 3.8 % Cu has been prepared by melting process at a temperature of 1200°C. The adding 12.5 wt% up to 20 wt% of SiC on Al-Cu alloys samples has been investigated. The structure analyses were examined by X-Ray Diffractometer (XRD) and scanning electron microscope (SEM). Moreover, the morphology of Al-Cu alloys has been seen as structure in micrometer range. The hardness was measured by hardness Vickers method. According to the results, it can be assumed that the 15 wt% of SiC content is prefer content to get better quality of back to back hardness Vickers of Al-Cu alloys.

Vztah mezi molekulární strukturou, nadmolekulární strukturou a mikromechanickými vlastnostmi semikrystalických polymerů

Czech Academy of Sciences Publication Activity Database

Šlouf, Miroslav; Krejčíková, Sabina; Hromádková, Jiřina

2017-01-01

Roč. 111, č. 4 (2017), s. 239-245 ISSN 0009-2770 R&D Projects: GA MŠk(CZ) LO1507 Institutional support: RVO:61389013 Keywords : semicrystalline polymers * microhardness * microindentation hardness testing Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 0.387, year: 2016 http://www.chemicke-listy.cz/common/article-vol_111-issue_4-page_239. html

Surface hardness evaluation of different composite resin materials: influence of sports and energy drinks immersion after a short-term period

Directory of Open Access Journals (Sweden)

Ugur Erdemir

2013-04-01

Full Text Available Objectives: This study evaluated the effect of sports and energy drinks on the surface hardness of different composite resin restorative materials over a 1-month period. Material and Methods: A total of 168 specimens: Compoglass F, Filtek Z250, Filtek Supreme, and Premise were prepared using a customized cylindrical metal mould and they were divided into six groups (N=42; n=7 per group. For the control groups, the specimens were stored in distilled water for 24 hours at 37°C and the water was renewed daily. For the experimental groups, the specimens were immersed in 5 mL of one of the following test solutions: Powerade, Gatorade, X-IR, Burn, and Red Bull, for two minutes daily for up to a 1-month test period and all the solutions were refreshed daily. Surface hardness was measured using a Vickers hardness measuring instrument at baseline, after 1-week and 1-month. Data were statistically analyzed using Multivariate repeated measure ANOVA and Bonferroni's multiple comparison tests (α=0.05. Results: Multivariate repeated measures ANOVA revealed that there were statistically significant differences in the hardness of the restorative materials in different immersion times (p<0.001 in different solutions (p<0.001. The effect of different solutions on the surface hardness values of the restorative materials was tested using Bonferroni's multiple comparison tests, and it was observed that specimens stored in distilled water demonstrated statistically significant lower mean surface hardness reductions when compared to the specimens immersed in sports and energy drinks after a 1-month evaluation period (p<0.001. The compomer was the most affected by an acidic environment, whereas the composite resin materials were the least affected materials. Conclusions: The effect of sports and energy drinks on the surface hardness of a restorative material depends on the duration of exposure time, and the composition of the material.

Effects of various light curing methods on the leachability of uncured substances and hardness of a composite resin.

Science.gov (United States)

Moon, H-J; Lee, Y-K; Lim, B-S; Kim, C-W

2004-03-01

The purpose of this study was to evaluate the effect of the various light curing units (plasma arc, halogen and light-emitting diodes) and irradiation methods (one-step, two-step and pulse) using different light energy densities on the leachability of unreacted monomers (Bis-GMA and UDMA) and the surface hardness of a composite resin (Z250, 3M). Leachability of the specimens immersed for 7 days in ethanol was analysed by HPLC. Vicker's hardness number (VHN) was measured immediately after curing (IC) and after immersion in ethanol for 7 days. Various irradiation methods with three curing units resulted in differences in the amount of leached monomers and VHN of IC when light energy density was lower than 17.0 J cm(-2) (P = 0.05). However, regardless of curing units and irradiation methods, these results were not different when the time or light energy density increased. When similar light energy density was irradiated (15.6-17.7 J cm(-2)), the efficiency of irradiation methods was different by the following order: one-step > or = two-step > pulse. These results suggest that the amount of leached monomers and VHN were influenced by forming polymer structure in activation and initiation stages of polymerization process with different light source energies and curing times.

Sintering Behavior of Spark Plasma Sintered SiC with Si-SiC Composite Nanoparticles Prepared by Thermal DC Plasma Process.

Science.gov (United States)

Yu, Yeon-Tae; Naik, Gautam Kumar; Lim, Young-Bin; Yoon, Jeong-Mo

2017-11-25

The Si-coated SiC (Si-SiC) composite nanoparticle was prepared by non-transferred arc thermal plasma processing of solid-state synthesized SiC powder and was used as a sintering additive for SiC ceramic formation. Sintered SiC pellet was prepared by spark plasma sintering (SPS) process, and the effect of nano-sized Si-SiC composite particles on the sintering behavior of micron-sized SiC powder was investigated. The mixing ratio of Si-SiC composite nanoparticle to micron-sized SiC was optimized to 10 wt%. Vicker's hardness and relative density was increased with increasing sintering temperature and holding time. The relative density and Vicker's hardness was further increased by reaction bonding using additional activated carbon to the mixture of micron-sized SiC and nano-sized Si-SiC. The maximum relative density (97.1%) and Vicker's hardness (31.4 GPa) were recorded at 1800 °C sintering temperature for 1 min holding time, when 0.2 wt% additional activated carbon was added to the mixture of SiC/Si-SiC.

Mineral and water content of A. gigas scales determine local micromechanical properties and energy dissipation mechanisms

Science.gov (United States)

Troncoso, Omar P.; Gigos, Florian; Torres, Fernando G.

2017-11-01

Arapaima gigas scales are natural laminated composite materials made of individual layers with different degrees of mineralization, accompanied of varying mechanical properties. This natural design provides scales with hardness and flexibility, and can serve as a source of inspiration for the development of new layered composites with a hard surface and flexible base. In this paper, we have carried out cyclic micro-indentation tests on both; the internal and the highly mineralized external surface of air dried and wet scales, in order to assess the variation of their local micromechanical properties with regard to the mineral and water content. The load-penetration (P-h) curves showed that creep takes place throughout the application of a constant force during the micro-indentation tests, confirming the time dependent response of A. gigas scales. A model that accounted for the elastic, plastic and viscous responses of the samples was used to fit the experimental results. The penetration depth during loading and creep, as well as the energy dissipated are dependent on the water content. The used model suggests that the viscous response of the internal layer increases with the water content.

Microhardness studies on nonlinear optical L-alanine single crystals

Indian Academy of Sciences (India)

2016-08-26

Aug 26, 2016 ... ... increasing load. Meyer's index number () calculated from v shows that the material belongs to the soft material category. Using Wooster's empirical relation, the elastic stiffness constant (11) was calculated from Vickers hardness values. Young's modulus was calculated using Knoop hardness values.

Effect of Mo-Fe substitution on glass forming ability, thermal stability, and hardness of Fe-C-B-Mo-Cr-W bulk amorphous alloys

Energy Technology Data Exchange (ETDEWEB)

Khalifa, Hesham E.; Cheney, Justin L. [University of California, San Diego Materials Science and Engineering Program, 9500 Gilman Drive, La Jolla, CA 92093-0411 (United States); Vecchio, Kenneth S. [University of California, San Diego Department of NanoEngineering, 9500 Gilman Drive, La Jolla, CA 92093-0411 (United States)], E-mail: kvecchio@ucsd.edu

2008-08-25

Amorphous Fe{sub 67-x}C{sub 10}B{sub 9}Mo{sub 7+x}Cr{sub 4}W{sub 3} (x = 1-7 at.%) plates with 640 {mu}m thickness were prepared by copper mold casting. The thermal properties and microstructural development during heat treatments were investigated by a combination of differential scanning calorimetry (DSC), differential thermal analysis, and X-ray diffractometry (XRD). The glass forming ability (GFA) and activation energy for crystallization have a distinct dependence on Mo content. Fe{sub 62}C{sub 10}B{sub 9}Mo{sub 12}Cr{sub 4}W{sub 3} is the best glass former in this study, demonstrating a supercooled liquid region, {delta}T{sub x} = 51 K, and an activation energy for crystallization, Q = 453 kJ/mol. The GFA of alloys in this system was governed by elastic strain optimization resulting directly from the variation in Mo content. Heat treatments were performed to demonstrate resistance to crystallization under typical processing conditions. Alloys in this system exhibited a three-phase evolution during crystallization. A second set of heat treatments was performed to identify each phase. Hardness data was collected at each of the heat treatment conditions, and a bulk metallic glasses (BMG)-derived composite containing a Mo-rich phase exhibited Vickers Hardness in excess of 2000. The fully amorphous alloys had an average hardness approaching 1500.

Microstructure and hardness studies of Inconel 718 manufactured by selective laser melting before and after solution heat treatment

International Nuclear Information System (INIS)

Tucho, Wakshum M.; Cuvillier, Priscille; Sjolyst-Kverneland, Atle; Hansen, Vidar

2017-01-01

The microstructure of Additive Manufactured (AM) Inconel 718 in general and Selective Laser Melting (SLM), in particular is different from the material produced by conventional methods due to the rapid solidification process associated with the former. As a result, the widely adapted standard solution heat treatment temperature (<1100 °C) for conventional material is found to be not high enough for materials fabricated with SLM method in order to dissolve Laves and other microsegregated phases for releasing the ageing constituents (Nb, Ti, Al) sufficiently into the alloy matrix. In this study, sample of Inconel 718 fabricated with SLM method were solution heat-treated to 1100 °C or 1250 °C at different hold times to investigate the dissolution of macro- and micro-segregated precipitates. Investigations of microstructure and segregation in as-printed and solution heat-treated states have been studied using Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM) and Optical Microscopy (OM). Measurement of material hardness was performed with Vickers hardness tests. The microstructure of the as-printed parts exhibit non-columnar grains, but contain well-shaped columnar/cellular sub-grains. The intergranular boundaries are decorated with high density of dislocations and segregated particles. Tremendous stress relief and grain coarsening were observed with solution heat treatment. In particular, at 1250 °C annealing, the sub-grains, including precipitates and dislocation networks along the sub-grain boundaries, were entirely dissolved. However, the 1100/1250 °C solution heat treatment scheme could not dissolve microsegregated precipitates and carbides completely. Details of the analysis on microstructure, dissolution of precipitates and hardness are presented.

Microstructure and hardness studies of Inconel 718 manufactured by selective laser melting before and after solution heat treatment

Energy Technology Data Exchange (ETDEWEB)

Tucho, Wakshum M., E-mail: wakshum.m.tucho@uis.no [Department of Mechanical and Structural Engineering and Materials Science, University of Stavanger, N-4036 Stavanger (Norway); Cuvillier, Priscille [Department of Mechanical and Structural Engineering and Materials Science, University of Stavanger, N-4036 Stavanger (Norway); Sjolyst-Kverneland, Atle [Roxar/Emerson Process Management, POB 112, 4065 Stavanger (Norway); Hansen, Vidar [Department of Mechanical and Structural Engineering and Materials Science, University of Stavanger, N-4036 Stavanger (Norway)

2017-03-24

The microstructure of Additive Manufactured (AM) Inconel 718 in general and Selective Laser Melting (SLM), in particular is different from the material produced by conventional methods due to the rapid solidification process associated with the former. As a result, the widely adapted standard solution heat treatment temperature (<1100 °C) for conventional material is found to be not high enough for materials fabricated with SLM method in order to dissolve Laves and other microsegregated phases for releasing the ageing constituents (Nb, Ti, Al) sufficiently into the alloy matrix. In this study, sample of Inconel 718 fabricated with SLM method were solution heat-treated to 1100 °C or 1250 °C at different hold times to investigate the dissolution of macro- and micro-segregated precipitates. Investigations of microstructure and segregation in as-printed and solution heat-treated states have been studied using Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM) and Optical Microscopy (OM). Measurement of material hardness was performed with Vickers hardness tests. The microstructure of the as-printed parts exhibit non-columnar grains, but contain well-shaped columnar/cellular sub-grains. The intergranular boundaries are decorated with high density of dislocations and segregated particles. Tremendous stress relief and grain coarsening were observed with solution heat treatment. In particular, at 1250 °C annealing, the sub-grains, including precipitates and dislocation networks along the sub-grain boundaries, were entirely dissolved. However, the 1100/1250 °C solution heat treatment scheme could not dissolve microsegregated precipitates and carbides completely. Details of the analysis on microstructure, dissolution of precipitates and hardness are presented.

Depth-Sensing Microindentation Studies of Melt Spun Al-12wt%Si-0.5wt%Sb Alloys

International Nuclear Information System (INIS)

Uzun, O.

2004-01-01

In this study, the indentation load-penetration depth curves of melt spun ribbons were measured under different peak load levels. The unloading segments of these curves were analyzed using widely adopted Oliver and Pharr method. It was found that both hardness and Youngs modulus exhibit significant peak load dependence. Empirical approaches were then proposed to determine the load independent hardness, H0, and modulus. The load independent hardness (1135.07 and 756.72 MPa) and modulus (13.4 and 7.2 GPa) values were then calculated for wheel and air side of the ribbon, respectively. The results showed that the reduced elastic modulus increases with increasing hardness

Experimental investigation into the crack propagation in multiphase tantalum carbide ceramics

Energy Technology Data Exchange (ETDEWEB)

Schulz, Bradford C. [Department of Metallurgical & Materials Engineering, The University of Alabama, 301 7th Avenue, 116 Houser Hall, Tuscaloosa, AL 35487-0202 (United States); Lee, HeeDong; Mogilevsky, Pavel [UES, Inc., 4401 Dayton-Xenia Road, Dayton, OH 45432-1894 (United States); Weinberger, Christopher R. [Department of Mechanical Engineering, Colorado State University, 1374 Campus Delivery, Fort Collins, CO 80523 (United States); Parthasarathy, Triplicane A. [UES, Inc., 4401 Dayton-Xenia Road, Dayton, OH 45432-1894 (United States); Matson, Lawrence E. [Air Force Research Laboratory Materials & Manufacturing Directorate, Structural Material Division (AFRL/RXLN), 2230 Tenth St., Wright-Patterson AFB, OH 4543307817 (United States); Smith, Chase [Department of Metallurgical & Materials Engineering, The University of Alabama, 301 7th Avenue, 116 Houser Hall, Tuscaloosa, AL 35487-0202 (United States); Thompson, Gregory B., E-mail: gthompson@eng.ua.edu [Department of Metallurgical & Materials Engineering, The University of Alabama, 301 7th Avenue, 116 Houser Hall, Tuscaloosa, AL 35487-0202 (United States)

2017-05-17

Tantalum carbide ceramics with high volume fractions of the ζ-Ta{sub 4}C{sub 3} phase have been shown to exhibit high fracture strength and toughness as compared to those in absence of this phase. In this work, we investigated how microcracks propagated in this these high toughness ceramics using Knoop and Vickers microindentation. The Knoop indentations demonstrated that cracking preferentially occurred parallel to the lath structure in ζ-Ta{sub 4}C{sub 3}; however shorter cracks did form between the laths when a sufficient driving force was present. The resulting crack path was tortuous providing direct evidence for toughening through crack deflection; however, the microscale nature of the work cannot rule out crack bridging as a toughening mechanism as well. Plasticity is also observed under the indents, but is likely a result of the high confining pressures that occurred during indentation allowing for plastic flow.

Plasma spray formed near-net-shape MoSi2-Si3N4 bulk nanocomposites-structure property evaluation

International Nuclear Information System (INIS)

Hong, S.J.; Viswanathan, V.; Rea, K.; Patil, S.; Deshpande, S.; Georgieva, P.; McKechnie, T.; Seal, S.

2005-01-01

This article, for the first time, presents the challenges toward the successful consolidation of near-net-shape bulk MoSi 2 -Si 3 N 4 -SiC nanocomposite using plasma spray forming. A detailed characterization of the spray formed bulk nanocomponent has been performed using optical microscopy (OM), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), and Vickers hardness testing. Vickers hardness (900 Hv) and fracture toughness (∼>5 MPa m 1/2 ) of the nanocomposite showed a little deviation from the expected, which might be due to the difference in the particle (Si 3 N 4 ) size and their distribution in the MoSi 2 matrix as a function of component thickness. Relatively higher hardness is attributed to the retention of the nanostructure in the composite. In addition, the as fabricated bulk nanocomposite showed enhanced oxidation resistance

Evaluation of a Degradation of Thermal Barrier Coating for Gas Turbine Blade

Energy Technology Data Exchange (ETDEWEB)

Kim, Dae Jin; Lee, Dong Hoon; Koo, Jae Mean; Seok, Chang Sung [Sungkyunkwan Univ., Seoul (Korea, Republic of); Kim, Mun Young; Yang, Sung Ho; Park, Sang Yoel [Korea Power Engineering Company, Inc., Yongin (Korea, Republic of)

2007-07-01

Thermal barrier coating system for gas turbine blade were thermally aged by isothermal heating in the furnace varing aging time and temperature. Then, micro Vickers hardness test was done for the cross section of bond coat and Ni-based superalloy substrate. Also, the thickness of TGO was measured by image analyzer and the changes in the microstructure and element distributions in the coating were analyzed by optical microscope and SEM-EDX analysis. No significant changes in the Vickers hardness of the bond coat were observed as the coated specimen was aged at high temperature and delaminations near between top coat and bond coat occurred when the coatings were aged for 50 hr at over 1,151 .deg. C.

Hardness Optimization for Al6061-MWCNT Nanocomposite Prepared by Mechanical Alloying Using Artificial Neural Networks and Genetic Algorithm

Directory of Open Access Journals (Sweden)

Mehrdad Mahdavi Jafari

2017-06-01

Full Text Available Among artificial intelligence approaches, artificial neural networks (ANNs and genetic algorithm (GA are widely applied for modification of materials property in engineering science in large scale modeling. In this work artificial neural network (ANN and genetic algorithm (GA were applied to find the optimal conditions for achieving the maximum hardness of Al6061 reinforced by multiwall carbon nanotubes (MWCNTs through modeling of nanocomposite characteristics. After examination the different ANN architectures an optimal structure of the model, i.e. 6-18-1, is obtained with 1.52% mean absolute error and R2 = 0.987. The proposed structure was used as fitting function for genetic algorithm. The results of GA simulation predicted that the combination sintering temperature 346 °C, sintering time 0.33 h, compact pressure 284.82 MPa, milling time 19.66 h and vial speed 310.5 rpm give the optimum hardness, (i.e., 87.5 micro Vickers in the composite with 0.53 wt% CNT. Also, sensitivity analysis shows that the sintering time, milling time, compact pressure, vial speed and amount of MWCNT are the significant parameter and sintering time is the most important parameter. Comparison of the predicted values with the experimental data revealed that the GA–ANN model is a powerful method to find the optimal conditions for preparing of Al6061-MWCNT.

Effect of multiple repairs in girth welds of pipelines on the mechanical properties

International Nuclear Information System (INIS)

Vega, O.E.; Hallen, J.M.; Villagomez, A.; Contreras, A.

2008-01-01

This work presents the results of multiple weld repairs in the same area in seamless API X-52 microalloyed steel pipe. Four conditions of shielded metal arc welding repairs and one as-welded specimen of the girth weld were characterized to determine changes in the microstructure, grain size in the heat affected zone, and to evaluate their effect on the mechanical properties of the weld joints. The mechanical properties by means of tension tests, Charpy-V impact resistance and Vickers hardness of the welds were analyzed. The results indicate that significant changes are not generated in the microstructural constituents of the heat affected zone. Grain growth in the heat affected zone at the specimen mid-thickness with the number of repairs was observed. Tensile strength of the weld joints meets the requirement of the API 1104 standard even after the fourth weld repair. Significant reduction in Charpy-V impact resistance with the number of weld repairs was found when the notch location was in the intersection of the fusion line with the specimen mid-thickness. A significant increase in the Vickers hardness of the heat affected zone occurred after the first repair and a gradual decrease in the Vickers hardness occurred as the number of repairs increases

Effects of sintering temperature on the mechanical properties of sintered NdFeB permanent magnets prepared by spark plasma sintering

International Nuclear Information System (INIS)

Wang, G.P.; Liu, W.Q.; Huang, Y.L.; Ma, S.C.; Zhong, Z.C.

2014-01-01

Sintered NdFeB-based permanent magnets were fabricated by spark plasma sintering (SPS) and a conventional method to investigate the mechanical and magnetic properties. The experimental results showed that sintered NdFeB magnet prepared by the spark plasma sintering (SPS NdFeB) possesses a better mechanical properties compared to the conventionally sintered one, of which the maximum value of bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively. The effects of sintering temperature on bending strength and Vickers hardness were investigated. It was shown that the bending strength firstly increases to the maximum value and then decreases with the increase of sintering temperature in a certain range. The investigations of microstructures and mechanical properties indicated that the unique sintering mechanism in the SPS process is responsible for the improvement of mechanical properties of SPS NdFeB. Furthermore, the relations between the mechanical properties and relevant microstructure have been analyzed based on the experimental fact. - Highlights: • Studied the sintering temperature effect on strengthening mechanism of NdFeB magnet firstly. • It showed that sintering temperature may effectively affect the mechanical properties. • The maximum bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively

Effects of sintering temperature on the mechanical properties of sintered NdFeB permanent magnets prepared by spark plasma sintering

Energy Technology Data Exchange (ETDEWEB)

Wang, G.P., E-mail: wgp@jxnu.edu.cn [College of Physics and Communication Electronics, Jiangxi Normal University, Nanchang 330022 (China); Liu, W.Q. [Key Laboratory of Advanced Functional Materials Science and Engineering, Ministry of Education, Beijing University of Technology, Beijing 100022 (China); Huang, Y.L.; Ma, S.C.; Zhong, Z.C. [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China)

2014-01-15

Sintered NdFeB-based permanent magnets were fabricated by spark plasma sintering (SPS) and a conventional method to investigate the mechanical and magnetic properties. The experimental results showed that sintered NdFeB magnet prepared by the spark plasma sintering (SPS NdFeB) possesses a better mechanical properties compared to the conventionally sintered one, of which the maximum value of bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively. The effects of sintering temperature on bending strength and Vickers hardness were investigated. It was shown that the bending strength firstly increases to the maximum value and then decreases with the increase of sintering temperature in a certain range. The investigations of microstructures and mechanical properties indicated that the unique sintering mechanism in the SPS process is responsible for the improvement of mechanical properties of SPS NdFeB. Furthermore, the relations between the mechanical properties and relevant microstructure have been analyzed based on the experimental fact. - Highlights: • Studied the sintering temperature effect on strengthening mechanism of NdFeB magnet firstly. • It showed that sintering temperature may effectively affect the mechanical properties. • The maximum bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively.

On the quench sensitivity of 7010 aluminum alloy forgings in the overaged condition

Energy Technology Data Exchange (ETDEWEB)

Tiryakioğlu, Murat, E-mail: m.tiryakioglu@unf.edu [School of Engineering, University of North Florida, Jacksonville, FL 32224 (United States); Robinson, Jeremy S. [Department of Mechanical, Aeronautical and Biomedical Engineering, University of Limerick, Limerick (Ireland); Eason, Paul D. [School of Engineering, University of North Florida, Jacksonville, FL 32224 (United States)

2014-11-17

The quench sensitivity of an overaged 7010 alloy forging was characterized by tensile and Vickers hardness tests, as well as scanning electron microscopy. Longitudinal tensile specimens, excised from a rectilinear open die forging were cooled from the solution treatment temperature following thirty-two different cooling paths including interrupted and delayed quenches. SEM analysis of the microstructure showed that quench precipitates were (i) Al{sub 2}CuMg (S) which nucleated heterogeneously on grain boundaries and (ii) Mg(Zn,Cu,Al){sub 2} (η) on grain boundaries, dispersoid bands, subgrain boundaries as well as in the aluminum matrix. The quench sensitivity of the alloy's yield strength and Vickers hardness was modeled simultaneously by quadruple-C curves, using an improved methodology for Quench Factor Analysis. The four C-curves used in the model represented loss of solute by (i) precipitation of S on grain boundaries, and precipitation of η (ii) on grain boundaries and dispersoid bands, (iii) on subgrain boundaries and (iv) in the matrix. The model yielded coefficient of determination (R{sup 2}) values of 0.967 and 0.974 for yield strength and Vickers hardness, respectively. The model and the implications of the results are discussed in this paper.

Manufacturing Feasibility and Forming Properties of Cu-4Sn in Selective Laser Melting.

Science.gov (United States)

Mao, Zhongfa; Zhang, David Z; Wei, Peitang; Zhang, Kaifei

2017-03-24

Copper alloys, combined with selective laser melting (SLM) technology, have attracted increasing attention in aerospace engineering, automobile, and medical fields. However, there are some difficulties in SLM forming owing to low laser absorption and excellent thermal conductivity. It is, therefore, necessary to explore a copper alloy in SLM. In this research, manufacturing feasibility and forming properties of Cu-4Sn in SLM were investigated through a systematic experimental approach. Single-track experiments were used to narrow down processing parameter windows. A Greco-Latin square design with orthogonal parameter arrays was employed to control forming qualities of specimens. Analysis of variance was applied to establish statistical relationships, which described the effects of different processing parameters (i.e., laser power, scanning speed, and hatch space) on relative density (RD) and Vickers hardness of specimens. It was found that Cu-4Sn specimens were successfully manufactured by SLM for the first time and both its RD and Vickers hardness were mainly determined by the laser power. The maximum value of RD exceeded 93% theoretical density and the maximum value of Vickers hardness reached 118 HV 0.3/5. The best tensile strength of 316-320 MPa is inferior to that of pressure-processed Cu-4Sn and can be improved further by reducing defects.

DETERMINATION OF VICKERS MICROHARDNESS IN β-Ga2O3 SINGLE CRYSTALS GROWN FROM THEIR OWN MELT

Directory of Open Access Journals (Sweden)

L. I. Guzilova

2015-05-01

Full Text Available The results of microhardness measurements of β-Ga2O3 single crystals for (001 crystallographic face are reported. The crystals were grown by the free crystallization with the "Garnet-2M" equipment. Microhardness values ​​ were determined by the Vickers method at varying loads. A four-sided diamond pyramid was used as an indenter. The average value of gallium oxide microhardness was equal to 8.91 GPa. We have carried out comparison of the values ​​obtained with the microhardness for the other wide bandgap semiconductors - epitaxial GaN layers grown on 6H-SiC and GaP layers grown on GaP:S. The findings are usable for machining process development of β-Ga2O3 single crystal substrates. In particular, silicon carbide and electrocorundum may be recommended for β-Ga2O3 machine processing.

Effects of aging temperature on electrical conductivity and hardness of Cu-3 at. pct Ti alloy aged in a hydrogen atmosphere

KAUST Repository

Semboshi, S.

2011-08-01

To improve the balance of the electrical conductivity and mechanical strength for dilute Cu-Ti alloys by aging in a hydrogen atmosphere, the influence of aging temperature ranging from 673 K to 773 K (400 °C to 500 °C) on the properties of Cu-3 at. pct Ti alloy was studied. The Vickers hardness increases steadily with aging time and starts to fall at 3 hours at 773 K (500 °C), 10 hours at 723 K (450 °C), or over 620 hours at 673 K (400 °C), which is the same as the case of conventional aging in vacuum. The maximum hardness increases from 220 to 236 with the decrease of aging temperature, which is slightly lower than aging at the same temperature in vacuum. The electrical conductivity at the maximum hardness also increases from 18 to 32 pct of pure copper with the decrease of the temperature, which is enhanced by a factor of 1.3 to 1.5 in comparison to aging in vacuum. Thus, aging at 673 K (400 °C) in a hydrogen atmosphere renders fairly good balance of strength and conductivity, although it takes nearly a month to achieve. The microstructural changes during aging were examined by transmission electron microscopy (TEM) and atom-probe tomography (APT), it was confirmed that precipitation of the Cu4Ti phase occurs first and then particles of TiH2 form as the third phase, thereby efficiently removing the Ti solutes in the matrix.

Revisiting the definition of local hardness and hardness kernel.

Science.gov (United States)

Polanco-Ramírez, Carlos A; Franco-Pérez, Marco; Carmona-Espíndola, Javier; Gázquez, José L; Ayers, Paul W

2017-05-17

An analysis of the hardness kernel and local hardness is performed to propose new definitions for these quantities that follow a similar pattern to the one that characterizes the quantities associated with softness, that is, we have derived new definitions for which the integral of the hardness kernel over the whole space of one of the variables leads to local hardness, and the integral of local hardness over the whole space leads to global hardness. A basic aspect of the present approach is that global hardness keeps its identity as the second derivative of energy with respect to the number of electrons. Local hardness thus obtained depends on the first and second derivatives of energy and electron density with respect to the number of electrons. When these derivatives are approximated by a smooth quadratic interpolation of energy, the expression for local hardness reduces to the one intuitively proposed by Meneses, Tiznado, Contreras and Fuentealba. However, when one combines the first directional derivatives with smooth second derivatives one finds additional terms that allow one to differentiate local hardness for electrophilic attack from the one for nucleophilic attack. Numerical results related to electrophilic attacks on substituted pyridines, substituted benzenes and substituted ethenes are presented to show the overall performance of the new definition.

Tensile and fracture toughness characteristics of Zr-2.5Nb pressure tube

International Nuclear Information System (INIS)

Jung, H. C.; Kim, Y. S.; Ahn, S. B.; Kim, S. S.; Im, K. S.

2004-01-01

The object of this study is to evaluate the characteristics of tensile and fracture toughness of Zr-2.5Nb pressure tube. The transverse tensile tests were performed at various temperatures and the fracture toughness tests were carried out at room temperature using the CCT (curved compact tension) specimen. These specimens were directly machined from the pressure tube retaining original curvatures. Also, the fracture toughness of two sets of Zr-2.5Nb manufactured at different time was compared. The chemical analysis and the Vicker's hardness tests were performed at two sets of Zr-2.5Nb pressure tube. The Vicker's hardness value of SET-2 containing more oxygen and carbon relatively was higher about 11 than that of SET-1

Crack-resistant Al2O3-SiO2 glasses.

Science.gov (United States)

Rosales-Sosa, Gustavo A; Masuno, Atsunobu; Higo, Yuji; Inoue, Hiroyuki

2016-04-07

Obtaining "hard" and "crack-resistant" glasses have always been of great important in glass science and glass technology. However, in most commercial glasses both properties are not compatible. In this work, colorless and transparent xAl2O3-(100-x)SiO2 glasses (30 ≤ x ≤ 60) were fabricated by the aerodynamic levitation technique. The elastic moduli and Vickers hardness monotonically increased with an increase in the atomic packing density as the Al2O3 content increased. Although a higher atomic packing density generally enhances crack formation in conventional oxide glasses, the indentation cracking resistance increased by approximately seven times with an increase in atomic packing density in binary Al2O3-SiO2 glasses. In particular, the composition of 60Al2O3 • 40SiO2 glass, which is identical to that of mullite, has extraordinary high cracking resistance with high elastic moduli and Vickers hardness. The results indicate that there exist aluminosilicate compositions that can produce hard and damage-tolerant glasses.

The characterization of Vicker's microhardness indentations and pile-up profiles as a strain-hardening microprobe

International Nuclear Information System (INIS)

Santos, C. Jr.

1998-04-01

Microhardness measurements have long been used to examine strength properties and changes in strength properties in metals, for example, as induced by irradiation. Microhardness affords a relatively simple test that can be applied to very small volumes of material. Microhardness is nominally related to the flow stress of the material at a fixed level of plastic strain. Further, the geometry of the pile-up of material around the indentation is related to the strain-hardening behavior of a material; steeper pile-ups correspond to smaller strain-hardening rates. In this study the relationship between pile-up profiles and strain hardening is examined using both experimental and analytical methods. Vickers microhardness tests have been performed on a variety of metal alloys including low alloy, high Cr and austenitic stainless steels. The pile-up topology around the indentations has been quantified using confocal microscopy techniques. In addition, the indentation and pile-up geometry has been simulated using finite element method techniques. These results have been used to develop an improved quantification of the relationship between the pile-up geometry and the strain-hardening constitutive behavior of the test material

Evaluation of crystalline changes and resistance to demineralization of the surface of human dental enamel treated with Er:YAG laser and fluoride using x-ray diffraction analysis and Vickers microhardness

Science.gov (United States)

Behroozibakhsh, Marjan; Shahabi, Sima; Ghavami-Lahiji, Mehrsima; Sadeghian, Safura; Sadat Faal Nazari, Neda

2018-06-01

This study aimed to investigate the changes in crystalline structure and resistance to demineralization of human dental surface enamel treated with erbium-doped yttrium aluminium garnet laser (Er:YAG) laser and fluoride. The enamel surfaces were divided into four groups according to the treatment process including, (L): irradiated with Er:YAG; (F): treated with acidulated phosphate fluoride gel (LF): Pre-irradiated surfaces with Er:YAG subjected to acidulated phosphate fluoride gel and (FL): laser irradiation was performed on the fluoridated enamel surface. Before and after the treatment procedure, the samples were evaluated using X-ray diffraction, scanning electron microscope (SEM) and the Vickers microhardness test. The surface microhardness values also were measured after a pH-cycling regime and acid challenge. The a-axis of all lased groups was contracted after treatment procedure. Measurement of the area under the peaks showed the highest crysallinity in the FL group. The hardness values of all laser treated samples significantly reduced after treatment procedure compared to the F group (p  ⩽  0.001). The morphological observations showed remarkable changes on the lased enamel surfaces including cracks, craters and exposed prisms. These findings suggest, irradiation of the Er:YAG laser accompanying with fluoride application can induce some beneficial crystalline changes regarding the acid-resistance properties of enamel, however, the craters and cracks produced by laser irradiation can promote enamel demineralization and consequently the positive effects of the Er:YAG laser will be eliminated.

Characterization of the Interface of an Alloy 625 Overlay on Steels Using Nanoindentation

Science.gov (United States)

Dai, Tao; Lippold, John

2018-06-01

Industry standards require postweld heat treatment (PWHT) to reduce the heat-affected zone hardness of steels such as F22 (2.25Cr-1Mo) and AISI 8630 overlaid (clad) with Alloy 625 weld metal. PWHT results in carbon diffusion and accumulation at the interface between the steel and overlay. The accumulation of carbon in a planar solidification growth zone adjacent to the fusion boundary results in high hardness and the potential for hydrogen-assisted cracking. The planar growth zone (PGZ) is so narrow that normal Vickers hardness testing cannot fully reveal the hardness distribution in this zone. This study focused on the application of nanoindentation to characterize the hardness in the narrow microstructural regions adjacent to the fusion boundary. The development of nanohardness maps revealed that the PGZ is not necessarily the region that exhibits peak hardness after PWHT. The highest hardness values were associated with clusters of M7C3 carbides in specific subregions in the PGZ and also in the partially-mixed zone adjacent to the fusion boundary or in steel "swirl" structures. It was also confirmed in this study that nanohardness has a linear correlation with Vickers hardness values. The results presented here provide new insight into the role of carbon diffusion during PWHT and its effect on interface embrittlement associated with Alloy 625 overlays on steel.

In vitro Comparison of the Effct Cola Beverage on Surface Hardness of Siloran-Based (p90 and Methyl Methacrylate-Based (p60 Composites

Directory of Open Access Journals (Sweden)

Z.Khamverdi

2016-11-01

Full Text Available Introduction: Th characteristics of a suitable restoration material is having acceptable mechanical properties, protecting teeth against decay and ease of use in clinics. Diet can affct properties of restorative materials in the mouth. Since amongst important properties of composite restorations are mechanical properties such as hardness, the aim of this study was evaluation of the effct of Coca-Cola Beverages on surface hardness of a silorane based p90( and methyl methacrylate p60( composites. Methods: In this experimental study, thirty disc-shaped specimens 5 × 2 mm( of each of methyl methacrylate based Filtek p60, 3M Dental Products, USA( and a silorane based Filtek p90, 3M Dental Products, USA( composite resins were prepared, according to manufacturers' instructions. Specimens were randomly divided to four groups as follows N = 15(: G1: Filtek p90 without exposure to Coca-Cola, G2: Filtek p90 with exposure to Coca-Cola, G3: Filtek p60 without expure to Coca-Cola, G4: Filtek p60 with expure to Coca-Cola. Th specimens were exposed to regular sof drinks Coca-Cola, Khoshgovar, Tehran, Iran( at room temperature for seven days with a frequency of three times daily for 20 minutes at a time. In the remaining times of the day, they were kept in distilled water. Thn, micro hardness measurements were made for each specimen with a Vickers hardness testing machine Buehler, Lake Bluff IL, USA( under 500 g of force for 15 seconds. Data were analyzed using SPSS 18 and independent t-test at a signifiance level of 0.05. Results: Micro hardness values of four groups were G1: 68.28 ± 2.65; G2:59.56 ± 6.61; G3: 93.5 ± 2.38; and G4:86.76 ± 5.47, respectively. Th results of this study showed that Coca-Cola reduces the surface hardness of the two composite materials P > 0.05(. Conclusions: Th results showed the hardness of both Filtek p90 and Filtek p60 composite signifiantly decreases with Coca-Cola but the reduction was equal.

Influence of Sn content on microstructural and mechanical properties of centrifugal cast Ti-Nb-Sn biomedical alloys; Efeitos da adicao de Sn na evolucao microestrutural e em propriedades mecanicas de ligas Ti-Nb-Sn biomedicas fundidas por centrifugacao

Energy Technology Data Exchange (ETDEWEB)

Lopes, E.S.N.; Contieri, R.J.; Caram, R., E-mail: ederlopes@fem.unicamp.b [Universidade Estadual de Campinas (DEMA/FEM/UNICAMP), SP (Brazil). Fac. de Engenharia Mecanica. Dept. de Engenharia de Materiais; Moraes, P.E.L. [FATEC Artur Azevedo, Mogi Mirim, SP (Brazil); Costa, A.M.S. [Universidade de Sao Paulo (DEMAR/EEL/USP), Lorena, SP (Brazil). Escola de Engenharia. Dept. de Engenharia de Materiais

2010-07-01

The arc voltaic centrifugal casting is an interesting alternative in terms of economic and technological development in the production of components based on materials with high reactivity and high melting point, such as titanium alloys. In this work, Ti-30Nb (wt. %) with additions of Sn (2, 4, 6, 8 and 10 wt. %) were formed by casting process. Characterization of the samples included optical microscopy, scanning electron microscopy, X-ray diffraction, Vickers hardness and elastic modulus measures by acoustic techniques. It was observed that the microstructure of the samples investigated is composed by dendritic structures, with clear segregation of alloying elements. The Vickers hardness and the elastic modulus decreased with the addition of Sn. The results show that the mechanical behavior of Ti-Nb alloys can be controlled within certain limits, by adding Sn. (author)

Influence of Sn content on microstructural and mechanical properties of centrifugal cast Ti-Nb-Sn biomedical alloys

International Nuclear Information System (INIS)

Lopes, E.S.N.; Contieri, R.J.; Caram, R.; Costa, A.M.S.

2010-01-01

The arc voltaic centrifugal casting is an interesting alternative in terms of economic and technological development in the production of components based on materials with high reactivity and high melting point, such as titanium alloys. In this work, Ti-30Nb (wt. %) with additions of Sn (2, 4, 6, 8 and 10 wt. %) were formed by casting process. Characterization of the samples included optical microscopy, scanning electron microscopy, X-ray diffraction, Vickers hardness and elastic modulus measures by acoustic techniques. It was observed that the microstructure of the samples investigated is composed by dendritic structures, with clear segregation of alloying elements. The Vickers hardness and the elastic modulus decreased with the addition of Sn. The results show that the mechanical behavior of Ti-Nb alloys can be controlled within certain limits, by adding Sn. (author)

Evaluation of Degradation of Isothermally Aged Plasma-Sprayed Thermal Barrier Coating

Energy Technology Data Exchange (ETDEWEB)

Koo, Jae Mean; Seok, Chang Sung; Kang, Min Sung; Kim, Dae Jin [Sungkyunkwan University, Seoul (Korea, Republic of); Lee, Dong Hoon [HYUNDAI STEEL CO., Incheon (Korea, Republic of); Kim, Mun Young [KPS Gas Turbine Technology Service Center, Seongnam (Korea, Republic of)

2010-04-15

The thermal barrier coating of a gas turbine blade was degraded by isothermal heating in a furnace and by varying the exposure time and temperature. Then, a micro-Vickers hardness test was conducted on the cross section of the bond coat and Ni-based superalloy substrate. Further, the thickness of TGO(Thermally Grown Oxide) was measured by using an image analyzer, and the changes in the microstructure and element contents in the coating were analyzed by using an optical microscope and by performing SEM-EDX analysis. No significant change was observed in the Vickers hardness of the bond coat when the coated specimen was degraded at a high temperature: delamination was observed between the top coat and the bond coat when the coating was degraded for 50 h at a temperature 1,151 .deg. C.

The comparison of the effects of different whitening toothpastes on the micro hardness of a nano hybrid composite resin.

Science.gov (United States)

Nainan, Mohan Thomas; Balan, Ashok Kalappurakkal; Sharma, Roshni; Thomas, Sabeena Susan; Deveerappa, Santhosh B

2014-11-01

The aim of this study was to compare the micro hardness of a nanohybrid composite resin after brushing with two herbal and one non-herbal whitening toothpastes. We divided Eighty disk-shaped specimens of a nanohybrid composite (Tetric N Ceram, Ivoclar Vivadent, Asia) into 4 groups of 20 specimens each: Groups A, B, C, and D. Group A was control, Group B was brushed with Colgate total advanced whitening (Colgate-Palmolive (India) Limited), Group C with Salt and Lemon, Dabur (Dabur International Limited, Dubai, UAE), and Group D with HiOra Shine, Himalaya (The Himalaya Drug Company, India). The specimens were polished using medium, fine, and superfine discs (Sof-lex, 3M, ESPE, USA) and subsequently placed at 37°C in distilled water. They were brushed for 2 minutes twice daily with a soft motorized toothbrush (Colgate 360 sonic power battery-operated tooth brush, Colgate Palmolive, India) for 30 days. The samples were rinsed under running water to remove the toothpaste and stored in distilled water at 37°C until the readout was taken on the Vickers's hardness tester for microhardness. The results revealed that the difference among the groups was statistically significant (P < 0.001). Tukey's test showed that reduction in microhardness for Group B was significantly higher than that for Group C and Group D (P < 0.001). Within the limitations of this study, non-herbal whitening toothpaste had a greater impact on the microhardness of nanohybrid resin composite than herbal whitening toothpastes.

Comparison of Knoop and Vickers surface microhardness and transverse microradiography for the study of early caries lesion formation in human and bovine enamel.

Science.gov (United States)

Lippert, F; Lynch, R J M

2014-07-01

The aims of the present laboratory study were twofold: a) to investigate the suitability of Knoop and Vickers surface microhardness (SMH) in comparison to transverse microradiography (TMR) to investigate early enamel caries lesion formation; b) to compare the kinetics of caries lesion initiation and progression between human and bovine enamel. Specimens (90×bovine and 90×human enamel) were divided into six groups (demineralization times of 8/16/24/32/40/48h) of 15 per enamel type and demineralized using a partially saturated lactic acid solution. SMH was measured before and after demineralization and changes in indentation length (ΔIL) calculated. Lesions were characterized using TMR. Data were analyzed (two-way ANOVA) and Pearson correlation coefficients calculated. ΔIL increased with increasing demineralization times but plateaued after 40h, whereas lesion depth (L) and integrated mineral loss (ΔZ) increased almost linearly throughout. No differences between Knoop and Vickers SMH in their ability to measure enamel demineralization were observed as both correlated strongly. Overall, ΔIL correlated strongly with ΔZ and L but only moderately with the degree of surface zone mineralization, whereas ΔZ and L correlated strongly. Bovine demineralized faster than human enamel (all techniques). Lesions in bovine formed faster than in human enamel, although the resulting lesions were almost indistinguishable in their mineral distribution characteristics. Early caries lesion demineralization can be sufficiently studied by SMH, but its limitations on the assessment of the mineral status of more demineralized lesions must be considered. Ideally, complementary techniques to assess changes in both physical and chemical lesion characteristics would be employed. Copyright © 2014 Elsevier Ltd. All rights reserved.

Collaboration for the Advancement of Indirect 3D Printing Technology

Energy Technology Data Exchange (ETDEWEB)

Cordero, Zachary C [ORNL; Elliott, Amy M [ORNL

2016-06-14

powder using I-3DP and molten bronze infiltration while maintaining the amorphous microstructure. X-ray diffraction, scanning electron microscopy, and differential thermal analysis were used to characterize the structural evolution of the powder feedstock during an infiltration heating cycle. Microindentation and bend tests were performed on the infiltrated material to evaluate its mechanical properties. It was found that infiltration improved both the ductility and strength of the sintered preforms by eliminating the stress concentration at the interparticle necks. The infiltrated material had an 11 GPa Vickers hardness and moderate damage tolerance, making it well-suited for applications requiring hard, net shape parts.

Comparison of mechanical properties of three machinable ceramics with an experimental fluorophlogopite glass ceramic.

Science.gov (United States)

Leung, Brian T W; Tsoi, James K H; Matinlinna, Jukka P; Pow, Edmond H N

2015-09-01

Fluorophlogopite glass ceramic (FGC) is a biocompatible, etchable, and millable ceramic with fluoride releasing property. However, its mechanical properties and reliability compared with other machinable ceramics remain undetermined. The purpose of this in vitro study was to compare the mechanical properties of 3 commercially available millable ceramic materials, IPS e.max CAD, Vitablocs Mark II, and Vita Enamic, with an experimental FGC. Each type of ceramic block was sectioned into beams (n=15) of standard dimensions of 2×2×15 mm. Before mechanical testing, specimens of the IPS e.max CAD group were further fired for final crystallization. Flexural strength was determined by the 3-point bend test with a universal loading machine at a cross head speed of 1 mm/min. Hardness was determined with a hardness tester with 5 Vickers hardness indentations (n=5) using a 1.96 N load and a dwell time of 15 seconds. Selected surfaces were examined by scanning electron microscopy and energy-dispersive x-ray spectroscopy. Data were analyzed by the 1-way ANOVA test and Weibull analysis (α=.05). Weibull parameters, including the Weibull modulus (m) as well as the characteristic strength at 63.2% (η) and 10.0% (B10), were obtained. A significant difference in flexural strength (PVita Enamic (145.95 ±12.65 MPa)>Vitablocs Mark II (106.67 ±18.50 MPa), and FGC (117.61 ±7.62 MPa). The Weibull modulus ranged from 6.93 to 18.34, with FGC showing the highest Weibull modulus among the 4 materials. The Weibull plot revealed that IPS e.max CAD>Vita Enamic>FGC>Vitablocs Mark II for the characteristic strength at both 63.2% (η) and 10.0% (B10). Significant difference in Vickers hardness among groups (PVitablocs Mark II (594.74 ±25.22 H(V))>Vita Enamic (372.29 ±51.23 H(V))>FGC (153.74 ±23.62 H(V)). The flexural strength and Vickers hardness of IPS e.max CAD were significantly higher than those of the 3 materials tested. The FGC's flexural strength was comparable with Vitablocs Mark II

A new approach to the estimation of surface free energy based on Vickers microhardness data

Directory of Open Access Journals (Sweden)

2009-03-01

Full Text Available A relation between surface free energy (σMHV and Meyer’s lines cut-values has been established using Vickers microhardness (MHV method and empirical physical laws. This relation allows the calculation of σMHV only from MHV data. The parameters required are Meyer’s lines cut-values and the mean value of diagonal length of the impression at different loads applied (drealmean. Our study of 12 samples of ultra high molecular weight polyethylene (PE-UHMW showed that the new approach is applicable when the slope value of Meyer’s lines equals 2 (i.e. n = 2. A γ-60Co source was used for the irradiation of 11 samples (one of the samples investigated is un-irradiated at room temperature in air. Doses of 1, 2, 5, 10, 20, 50, 100, 200, 500, 1000 and 1500 kGy were applied. The values of σMHV obtained are in a good agreement with the literature. The dependence of σMHV on the dose applied strictly corresponds to the radiation effects theory. MHV was measured at seven different loads – 0.0123, 0.0245, 0.049, 0.098, 0.196, 0.392, 0.785 N at a loading time of 30 s.

Room Temperature Elastic Moduli and Vickers Hardness of Hot-Pressed LLZO Cubic Garnet

Science.gov (United States)

2012-01-01

4140-steel [29] as well as composites such as Al/Al2O3 [30] and Ni– YSZ cermets [27]. The RUS apparatus used in this study consists of a computer...Microstructure and lattice parameter of LLZO specimens In this study , the LLZO microstructure was observed on a (i) fracture surface of LLZO-01 (Fig. 1a) and... study are consistent with the trend (Eq. 2) of a power law decrease in mechanical properties with increasing lattice parameter observed for other garnet

Effect of a self-adhesive coating on the load-bearing capacity of tooth-coloured restorative materials.

Science.gov (United States)

Bagheri, R; Palamara, Jea; Mese, A; Manton, D J

2017-03-01

The aim of this study was to compare the flexural strength and Vickers hardness of tooth-coloured restorative materials with and without applying a self-adhesive coating for up to 6 months. Specimens were prepared from three resin composites (RC), two resin-modified glass-ionomer cements (RM-GIC) and two conventional glass-ionomer cements (CGIC). All materials were tested both with and without applying G-Coat Plus (GCP). Specimens were conditioned in 37 °C distilled deionized water for 24 h, and 1, 3 and 6 months. The specimens were strength tested using a four-point bend test jig in a universal testing machine. The broken specimen's halves were used for Vickers hardness testing. Representative specimens were examined under an environmental scanning electron microscope. Data analysis showed that regardless of time and materials, generally the surface coating was associated with a significant increase in the flexural strength of the materials. Applying the GCP decreased the hardness of almost all materials significantly (P < 0.05) and effect of time intervals on hardness was material dependent. The load-bearing capacity of the restorative materials was affected by applying self-adhesive coating and ageing. The CGIC had significantly higher hardness but lower flexural strength than the RM-GIC and RC. © 2016 Australian Dental Association.

The rf-power dependences of the deposition rate, the hardness and the corrosion-resistance of the chromium nitride film deposited by using a dual ion beam sputtering system

International Nuclear Information System (INIS)

Lim, Jongmin; Lee, Chongmu

2006-01-01

The hexavalent chromium used in chromium plating is so toxic that it is very hazardous to human body and possibly causes cancer in humans. Therefore, it is indispensable to develop an alternative deposition technique. Dependences of the deposition rate, the phases, the hardness, the surface roughness and the corrosion-resistance of CrN x deposited on the high speed steel substrate by using a dual ion beam sputtering system on the rf-power were investigated to see the feasibility of sputtering as an alternative technique for chromium plating. The dual ion beam sputtering system used in this study was designed in such a way as the primary argon ion beam and the secondary nitrogen ion beam are injected toward the target and the substrate, respectively so that the chromium atoms at the chromium target surface may not nearly react with nitrogen atoms. The hardness and the surface roughness were measured by a micro-Vicker's hardness tester and an atomic force microscope (AFM), respectively. X-ray diffraction analyses were performed to identify phases in the films. The deposition rate of CrN x depends more strongly upon the rf-power for argon ion beam than that for nitrogen ion beam. The hardness of the CrN x film is highest when the volume percent of the Cr 2 N phase in the film is highest. Amorphous films are obtained when the rf-power for nitrogen ion beam is much higher than that for argon ion beam. The CrN x film deposited by using the sputtering technique under the optimal condition provides corrosion-resistance comparable to that of the electroplated chromium

Weibull modulus of hardness, bend strength, and tensile strength of Ni−Ta−Co−X metallic glass ribbons

Energy Technology Data Exchange (ETDEWEB)

Neilson, Henry J., E-mail: hjn2@case.edu [Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH (United States); Petersen, Alex S.; Cheung, Andrew M.; Poon, S. Joseph; Shiflet, Gary J. [University of Virginia, 395 McCormick Road, P.O. Box 400745, Charlottesville, VA 22904 (United States); Widom, Mike [Carnegie Mellon University, 5000 Forbes Avenue, Wean Hall 3325, Pittsburgh, PA 15213 (United States); Lewandowski, John J. [Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH (United States)

2015-05-14

In this study, the variations in mechanical properties of Ni−Co−Ta-based metallic glasses have been analyzed. Three different chemistries of metallic glass ribbons were analyzed: Ni{sub 45}Ta{sub 35}Co{sub 20}, Ni{sub 40}Ta{sub 35}Co{sub 20}Nb{sub 5}, and Ni{sub 30}Ta{sub 35}Co{sub 30}Nb{sub 5}. These alloys possess very high density (approximately 12.5 g/cm{sup 3}) and very high strength (e.g. >3 GPa). Differential scanning calorimetry (DSC) and x-ray diffraction (XRD) were used to characterize the amorphicity of the ribbons. Mechanical properties were measured via a combination of Vickers hardness, bending strength, and tensile strength for each chemistry. At least 50 tests were conducted for each chemistry and each test technique in order to quantify the variability of properties using both 2- and 3-parameter Weibull statistics. The variability in properties and their source(s) were compared to that of other engineering materials, while the nature of deformation via shear bands as well as fracture surface features have been determined using scanning electron microscopy (SEM). Toughness, the role of defects, and volume effects are also discussed.

Comparison of Mechanical Properties of Resin Composites with Resin Modified Glass Ionomers

Directory of Open Access Journals (Sweden)

Taha NA

2015-06-01

Full Text Available Statement of Problem: There are controversial reports regarding physical and mechanical properties of resin composites and glass ionomer cements. Some revealed higher strength and hardness for resin composites while others showed a comparable value for glass ionomer cements. Evaluation of mechanical properties of different types of resin composites in comparison with resin modified glass ionomers is not widely studied. Objectives: To measure and compare the flexural strength and Vickers hardness of three resin composites and two resins modified glass ionomer cements before and after ageing. Materials and Methods: Three resin composites, i.e. Filtek Supreme XTE (3M ESPE, Ice (SDI, Gradia (GC, and two resins modified glass ionomers, i.e. Fuji II LC (GC and Riva Light Cure (SDI, were selected. Ten barshaped specimens were prepared for each material and cured using LED curing light. After 24 hours storage in distilled water at 37oC, the specimens were randomly divided into two equal groups (n=5. The first group was tested as a baseline and the second group was restored at 37oC for another 29 days. Flexural strength was performed by four-point bending test using universal testing machine at crosshead speed of 0.5mm/min, and the maximum load at failure was recorded. The specimen’s halves were used for evaluating Vickers hardness, using a Digital Hardness Tester (300 g/15 sec and the Vickers hardness number (VHN was recorded. Data were analyzed using one-way analysis of variance (ANOVA, Tukey’s and student’s t-test. Results: After 24 hours of immersion, the highest hardness number was found for Filtek Supreme and Ice and the highest flexural strength was obtained for Gradia. After 30 days of storage, hardness of Fuji II LC and Gradia showed a significant decrease; flexural strength of Ice and Fuji II LC revealed a significant increase while Gradia and Filtek Supreme showed a significant decrease. Conclusions: Resin modified glass ionomers showed

Laser surface melting of 304 stainless steel for pitting corrosion resistance improvement

CSIR Research Space (South Africa)

Seleka, TS

2006-11-01

Full Text Available optical emission spectroscopy (GDOES) was utilized for chemical analysis. Changes in hardness were observed by using a Vickers microhardness tester. Pitting corrosion tests on laser treated and untreated samples were conducted according to ASTM G48...

Anti-scratch AlMgB14 Gorilla® Glass coating

Science.gov (United States)

Putrolaynen, V. V.; Grishin, A. M.; Rigoev, I. V.

2017-10-01

Hard aluminum-magnesium boride (BAM) films were fabricated onto Corning® Gorilla® Glass by radio-frequency magnetron sputtering of a single stoichiometric AlMgB14 target. BAM films exhibit a Vickers hardness from 10 to 30 GPa and a Young's modulus from 80 to 160 GPa depending on applied loading forces. Deposited hard coating increases the critical load at which glass substrate cracks. The adhesion energy of BAM films on Gorilla® Glass is 6.4 J/m2.

Crack-resistant Al2O3–SiO2 glasses

Science.gov (United States)

Rosales-Sosa, Gustavo A.; Masuno, Atsunobu; Higo, Yuji; Inoue, Hiroyuki

2016-01-01

Obtaining “hard” and “crack-resistant” glasses have always been of great important in glass science and glass technology. However, in most commercial glasses both properties are not compatible. In this work, colorless and transparent xAl2O3–(100–x)SiO2 glasses (30 ≤ x ≤ 60) were fabricated by the aerodynamic levitation technique. The elastic moduli and Vickers hardness monotonically increased with an increase in the atomic packing density as the Al2O3 content increased. Although a higher atomic packing density generally enhances crack formation in conventional oxide glasses, the indentation cracking resistance increased by approximately seven times with an increase in atomic packing density in binary Al2O3–SiO2 glasses. In particular, the composition of 60Al2O3•40SiO2 glass, which is identical to that of mullite, has extraordinary high cracking resistance with high elastic moduli and Vickers hardness. The results indicate that there exist aluminosilicate compositions that can produce hard and damage-tolerant glasses. PMID:27053006

Deposition and characterisation of multilayer hard coatings. Ti/TiNδ/TiCxNy/(TiC) a-C:H/(Ti) a-C:H

International Nuclear Information System (INIS)

Burinprakhon, T.

2001-02-01

and adhesion of the multilayer coated titanium substrates were assessed by using microindentation hardness and scratch tests, respectively. A simple hardness model containing parameters that assess the contributions from the coating and the substrate to the measured hardness was developed to describe hardness variation as a function of indentation size. This model allowed the determination of a coating hardness and an effective substrate hardness under interfacial constraint. The critical load of failure in the scratch test obtained for multilayer coated titanium substrates was in the range of 10 to 20 N. Post examination of the scratches showed that the interfacial region TiNδ/TiC x N y /(TiC m ) a-C:H was prone to delamination, in response to the scratch test. Complete de-bonding of this interfacial region was observed in the multilayer coating where a sharp interface between the TiC x N y interlayers of two different microstructures was present. (author)

Characteristic crystal orientation of folia in oyster shell, Crassostrea gigas

Energy Technology Data Exchange (ETDEWEB)

Lee, Seung Woo [Department of Chemical and Biomolecular Engineering, Sogang University, Seoul (Korea, Republic of); Kim, Gyeung Ho [Nano-Materials Reserch Center, Korea Institute of Science and Technology, Seoul (Korea, Republic of); Choi, Cheong Song [Department of Chemical and Biomolecular Engineering, Sogang University, Seoul (Korea, Republic of)], E-mail: cschoi@sogang.ac.kr

2008-03-10

The thin sheets of calcite, termed folia, that make up much of the shell of an oyster are composed of foliated lath. Folia of the giant Pacific oyster (Crassostrea gigas) were examined using TEM (transmission electron microscopy) and tested using microindentation and nanoindentation techniques. Analysis of the Kikuchi patterns obtained from the folia showed that there are two types (type I and type II) of preferred orientation, with an angle of around 70{sup o} between them. Nanoindentation tests showed that the folia exhibit a hardness of about 3 GPa and elastic modulus of about 73 GPa. Microcracks were generated using a microindenter in order to study the fracture mechanisms of the folia. Following on from these investigations, fracture mechanisms are discussed in conjunction with the correlation between preferred orientation and structural characteristics during cracking of the folia. Comparing the morphology and the polymorphism with nacre (also known as mother of pearl), the advantages of the relatively fast crystal growth and less amount of organic matrix in folia may have interesting implications for the development of sophisticated synthetic materials.

Case study of the gradient features of in situ concrete

Directory of Open Access Journals (Sweden)

Pengkun Hou

2014-01-01

Full Text Available The recognition of gradient features of the properties of in situ concrete is important for the interpretation/prediction of service life. In this work, the gradient features: water absorption, porosity, mineralogy, morphology and micromechanical properties were studied on two in situ road concretes (15 and 5 years old, respectively by weighing, MIP, XRD, IR, SEM/EDS and micro-indentation techniques. Results showed that a coarsening trend of the pores of the concrete leads to a gradual increase of liquid transport property from inside to outside. Although the carbonation of the exposed surface results in a compact microstructure of the paste, its combined action with calcium-leaching leads to a comparable porosity of different concrete layers. Moreover, the combining factors result in three morphological features, i.e. a porous and granular exposed-layer, a fibrous and porous subexposed-layer and a compact inner-layer. Micro-indentation test results showed that a hard layer that moves inward with aging exists due to the alterations of the mineralogy, the pore and the gel structure.

Microstructure and thermal stability of nickel layers electrodeposited from an additive-free sulphamate-based electrolyte

DEFF Research Database (Denmark)

Rasmussen, Anette Alsted; Møller, Per; Somers, Marcel A. J.

2006-01-01

and scanning electron microscopy and X-ray diffraction; the Vickers hardness was measured in cross sections. The present is meant as a reference for forthcoming articles on the investigation of various strengthening mechanisms on the microstructure, hardness and thermal stability of Ni (alloys) electrodeposits.......The influences of the current density and the temperature on the microstructure and hardness of Ni layers electrodeposited from an additive-free sulphamate bath were investigated. The microstructure and thermal stability of the electrodeposits was investigated with a combination of transmission...

Interaction between Yttria fully stabilized Zirconia or Yttria-Zirconia blended face-coat with Ti6Al4V during investment casting

CSIR Research Space (South Africa)

Mutombo, K

2014-10-01

Full Text Available The interaction between the Ti6Al4V alloy and the mould materials was investigated. The alpha-case was characterized by Vickers hardness tester, optical and scanning electron microscopy equipped with electron dispersive X-ray spectrometry (EDX). X-ray...

On the manufacturing of a gas turbine engine part through metal spinning process

Science.gov (United States)

Hassanin, A. El; Astarita, A.; Scherillo, F.; Velotti, C.; Squillace, A.; Liguori, A.

2018-05-01

Metal spinning processes represents an interesting alternative to traditional sheet metal forming processes in several industrial contexts, such as automotive and aerospace. In this work, the production of a combustion chamber liner top prototype using AISI 304L stainless steel is proposed, in order to evaluate the process feasibility for the required part geometry. The prototypes production was carried out using a two-stage semiautomatic spinning process. The effects in terms of wall thickness reduction were investigated. Using optical microscopy and Scanning Electron Microscopy (SEM) techniques, the microstructural behavior of the metal subjected to the forming process was investigated, while for an evaluation of the influence on the mechanical properties Vickers micro-indentation tests were performed. The main result of the process, as observed from all the investigation techniques adopted, is the formation of strain induced martensite due to the severe plastic deformation and cold reduction of the material, ranging in this case from 30% to 50%. In some areas of the part section, some rips indicating an excessive tensile stress were also detected.

Development and characterization of ceramic composites alumina-titania based reinforced with lanthanum oxide for fabrication of inert coatings for metallic tanks of the oil industry; Desenvolvimento e caracterizacao de compositos ceramicos baseados em alumina-titania reforcados com oxido de lantanio para fabricacao de revestimentos inertes em tanques metalicos da industria petrolifera

Energy Technology Data Exchange (ETDEWEB)

Bandeira, J.M.; Yadava, Y.P.; Silva, N.D.G.; Ferreira, R.A.S., E-mail: julianamb91@gmail.com, E-mail: yadava@ufpe.br [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Centro de Tecnologia e Geociencias. Departamento de Engenharia Mecanica

2016-07-01

Crude petroleum is highly corrosive causing superficial degradation in metallic tanks used for storage and transportation of this material, which causes a serious problem in the oil industry. An alternative to solve this problem is to use some kind of coating that is inert to this kind of corrosion. Alumina and titania are interesting materials for several engineering applications because, when compared with other ceramic materials, they present superior mechanical properties, e.g. high mechanical strength, good chemical stability and high fracture toughness combined with good wear resistance and a coefficient of thermal expansion close to the iron's, which makes them fit to use in ceramic hardening process and coating. In this paper, alumina-titania ceramic composites with 5%, 10%, 15% and 20% of titania (TiO2) and reinforced with 2% of lanthanum oxide of were produced by thermo-mechanical processing and sintering techniques at 1350 deg C. In these composites, microstructure and mechanical properties were analyzed using X-ray spectroscopy, optical microscopy, scanning electron microscopy and Vickers hardness in order to evaluate their applicability. X-ray spectroscopy showed the formation of composite without the presence of other phases. Optical microscopy and scanning electron microscopy showed a homogeneous microstructure in terms of particle size and distribution. Vickers hardness test showed a gradual decrease in hardness with the addition of titania. The composite with 5% of titania and 2% of lanthanum oxide is the best choice for structural applications. The composites were submerged in crude petroleum for 30 days to study their stability in such environment. Through the analysis of X-ray spectroscopy, optical microscopy and Vickers hardness before and after the submersion in crude petroleum, it was not observed structural or microstructural degradation nether alterations in mechanical properties. This way, it was concluded that these composites have

Development and characterization of ceramic composites alumina-titania based reinforced with lanthanum oxide for fabrication of inert coatings for metallic tanks of the oil industry

International Nuclear Information System (INIS)

Bandeira, J.M.; Yadava, Y.P.; Silva, N.D.G.; Ferreira, R.A.S.

2016-01-01

Crude petroleum is highly corrosive causing superficial degradation in metallic tanks used for storage and transportation of this material, which causes a serious problem in the oil industry. An alternative to solve this problem is to use some kind of coating that is inert to this kind of corrosion. Alumina and titania are interesting materials for several engineering applications because, when compared with other ceramic materials, they present superior mechanical properties, e.g. high mechanical strength, good chemical stability and high fracture toughness combined with good wear resistance and a coefficient of thermal expansion close to the iron's, which makes them fit to use in ceramic hardening process and coating. In this paper, alumina-titania ceramic composites with 5%, 10%, 15% and 20% of titania (TiO2) and reinforced with 2% of lanthanum oxide of were produced by thermo-mechanical processing and sintering techniques at 1350 deg C. In these composites, microstructure and mechanical properties were analyzed using X-ray spectroscopy, optical microscopy, scanning electron microscopy and Vickers hardness in order to evaluate their applicability. X-ray spectroscopy showed the formation of composite without the presence of other phases. Optical microscopy and scanning electron microscopy showed a homogeneous microstructure in terms of particle size and distribution. Vickers hardness test showed a gradual decrease in hardness with the addition of titania. The composite with 5% of titania and 2% of lanthanum oxide is the best choice for structural applications. The composites were submerged in crude petroleum for 30 days to study their stability in such environment. Through the analysis of X-ray spectroscopy, optical microscopy and Vickers hardness before and after the submersion in crude petroleum, it was not observed structural or microstructural degradation nether alterations in mechanical properties. This way, it was concluded that these composites have good

Y-TZP ceramic processing from coprecipitated powders: a comparative study with three commercial dental ceramics.

Science.gov (United States)

Lazar, Dolores R R; Bottino, Marco C; Ozcan, Mutlu; Valandro, Luiz Felipe; Amaral, Regina; Ussui, Valter; Bressiani, Ana H A

2008-12-01

(1) To synthesize 3mol% yttria-stabilized zirconia (3Y-TZP) powders via coprecipitation route, (2) to obtain zirconia ceramic specimens, analyze surface characteristics, and mechanical properties, and (3) to compare the processed material with three reinforced dental ceramics. A coprecipitation route was used to synthesize a 3mol% yttria-stabilized zirconia ceramic processed by uniaxial compaction and pressureless sintering. Commercially available alumina or alumina/zirconia ceramics, namely Procera AllCeram (PA), In-Ceram Zirconia Block (CAZ) and In-Ceram Zirconia (IZ) were chosen for comparison. All specimens (6mmx5mmx5mm) were polished and ultrasonically cleaned. Qualitative phase analysis was performed by XRD and apparent densities were measured on the basis of Archimedes principle. Ceramics were also characterized using SEM, TEM and EDS. The hardness measurements were made employing Vickers hardness test. Fracture toughness (K(IC)) was calculated. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey's test (alpha=0.05). ANOVA revealed that the Vickers hardness (pceramic materials composition. It was confirmed that the PA ceramic was constituted of a rhombohedral alumina matrix, so-called alpha-alumina. Both CAZ and IZ ceramics presented tetragonal zirconia and alpha-alumina mixture of phases. The SEM/EDS analysis confirmed the presence of aluminum in PA ceramic. In the IZ and CAZ ceramics aluminum, zirconium and cerium in grains involved by a second phase containing aluminum, silicon and lanthanum were identified. PA showed significantly higher mean Vickers hardness values (H(V)) (18.4+/-0.5GPa) compared to vitreous CAZ (10.3+/-0.2GPa) and IZ (10.6+/-0.4GPa) ceramics. Experimental Y-TZP showed significantly lower results than that of the other monophased ceramic (PA) (pceramics (pceramic processing conditions led to ceramics with mechanical properties comparable to commercially available reinforced ceramic materials.

Bond-orientational analysis of hard-disk and hard-sphere structures.

Science.gov (United States)

Senthil Kumar, V; Kumaran, V

2006-05-28

We report the bond-orientational analysis results for the thermodynamic, random, and homogeneously sheared inelastic structures of hard-disks and hard-spheres. The thermodynamic structures show a sharp rise in the order across the freezing transition. The random structures show the absence of crystallization. The homogeneously sheared structures get ordered at a packing fraction higher than the thermodynamic freezing packing fraction, due to the suppression of crystal nucleation. On shear ordering, strings of close-packed hard-disks in two dimensions and close-packed layers of hard-spheres in three dimensions, oriented along the velocity direction, slide past each other. Such a flow creates a considerable amount of fourfold order in two dimensions and body-centered-tetragonal (bct) structure in three dimensions. These transitions are the flow analogs of the martensitic transformations occurring in metals due to the stresses induced by a rapid quench. In hard-disk structures, using the bond-orientational analysis we show the presence of fourfold order. In sheared inelastic hard-sphere structures, even though the global bond-orientational analysis shows that the system is highly ordered, a third-order rotational invariant analysis shows that only about 40% of the spheres have face-centered-cubic (fcc) order, even in the dense and near-elastic limits, clearly indicating the coexistence of multiple crystalline orders. When layers of close-packed spheres slide past each other, in addition to the bct structure, the hexagonal-close-packed (hcp) structure is formed due to the random stacking faults. Using the Honeycutt-Andersen pair analysis and an analysis based on the 14-faceted polyhedra having six quadrilateral and eight hexagonal faces, we show the presence of bct and hcp signatures in shear ordered inelastic hard-spheres. Thus, our analysis shows that the dense sheared inelastic hard-spheres have a mixture of fcc, bct, and hcp structures.

Ti-Mo alloys employed as biomaterials: effects of composition and aging heat treatment on microstructure and mechanical behavior.

Science.gov (United States)

Cardoso, Flavia F; Ferrandini, Peterson L; Lopes, Eder S N; Cremasco, Alessandra; Caram, Rubens

2014-04-01

The correlation between the composition, aging heat treatments, microstructural features and mechanical properties of β Ti alloys is of primary significance because it is the foundation for developing and improving new Ti alloys for orthopedic biomaterials. However, in the case of Ti-Mo alloys, this correlation is not fully described in the literature. Therefore, the purpose of this study was to experimentally investigate the effect of composition and aging heat treatments on the microstructure, Vickers hardness and elastic modulus of Ti-Mo alloys. These alloys were solution heat-treated and water-quenched, after which their response to aging heat treatments was investigated. Their microstructure, Vickers hardness and elastic modulus were evaluated, and the results allow us to conclude that stabilization of the β phase is achieved with nearly 10% Mo when a very high cooling rate is applied. Young's modulus was found to be more sensitive to phase variations than hardness. In all of the compositions, the highest hardness values were achieved by aging at 723K, which was attributed to the precipitation of α and ω phases. All of the compositions aged at 573K, 623K and 723K showed overaging within 80h. © 2013 Published by Elsevier Ltd.

Radiation annealing mechanisms of low-alloy reactor pressure vessel steels dependent on irradiation temperature and neutron fluence

International Nuclear Information System (INIS)

Pachur, D.

1982-01-01

Heat treatment after irradiation of reactor pressure vessel steels showed annealing of irradiation embrittlement. Depending on the irradiation temperature, the embrittlement started to anneal at about 220 0 C and was completely annealed at 500 0 C with 4 h of annealing time. The annealing behavior was normally measured in terms of the Vickers hardness increase produced by irradiation relative to the initial hardness as a function of the annealing temperature. Annealing results of other mechanical properties correspond to hardness results. During annealing, various recovery mechanisms occur in different temperature ranges. These are characterized by activation energies from 1.5 to 2.1 eV. The individual mechanisms were determined by the different time dependencies at various temperatures. The relative contributions of the mechanisms showed a neutron fluence dependence, with the lower activation energy mechanisms being predominant at low fluence and vice versa. In the temperature range where partial annealing of a mechanism took place during irradiation, an increase in activation energy was observed. Trend curves for the increase in transition temperature with irradiation, for the relative increase of Vickers hardness and yield strength, and for the relative decrease of Charpy-V upper shelf energy are interpreted by the behavior of different mechanisms

Surface martensitization of Carbon steel using Arc Plasma Sintering

Science.gov (United States)

Wahyudi, Haris; Dimyati, Arbi; Sebayang, Darwin

2018-03-01

In this paper new technology of surface structure modification of steel by short plasma exposure in Arc Plasma Sintering (APS) device is presented. APS is an apparatus working based on plasma generated by DC pulsed current originally used for synthesizing materials via sintering and melting. Plasma exposure in APS was applied into the specimens for 1 and 3 seconds which generate temperature approximately about 1300-1500°C. The SUP9, pearlitic carbon steel samples were used. The hardness, hardening depth and microstructure of the specimens have been investigated by Vickers micro hardness test and Scanning Electron Microscopy (SEM) supported by Energy Dispersive X-Ray Spectroscopy (EDX). The results have showed that the mechanical property was significantly improved due to the formation of single martensitic structures as identified by SEM. The hardness of treated surface evaluated by Vickers hardness test showed significant improvement nearly three time from 190 VHN before to 524 VHN after treatment. Furthermore, EDX confirmed that the formation of martensite layer occurred without altering its composition. The APS also produced uniform hardened layer up to 250 μm. The experiment has demonstrated that arc plasma process was successfully improved the mechanical properties of steel in relatively very short time.

Photon technology. Hard photon technology; Photon technology. Hard photon gijutsu

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-03-01

Research results of hard photon technology have been summarized as a part of novel technology development highly utilizing the quantum nature of photon. Hard photon technology refers to photon beam technologies which use photon in the 0.1 to 200 nm wavelength region. Hard photon has not been used in industry due to the lack of suitable photon sources and optical devices. However, hard photon in this wavelength region is expected to bring about innovations in such areas as ultrafine processing and material synthesis due to its atom selective reaction, inner shell excitation reaction, and spatially high resolution. Then, technological themes and possibility have been surveyed. Although there are principle proposes and their verification of individual technologies for the technologies of hard photon generation, regulation and utilization, they are still far from the practical applications. For the photon source technology, the laser diode pumped driver laser technology, laser plasma photon source technology, synchrotron radiation photon source technology, and vacuum ultraviolet photon source technology are presented. For the optical device technology, the multi-layer film technology for beam mirrors and the non-spherical lens processing technology are introduced. Also are described the reduction lithography technology, hard photon excitation process, and methods of analysis and measurement. 430 refs., 165 figs., 23 tabs.

Radial dependence of the microstructure in a HPT Cu-Zr-Ti disc

International Nuclear Information System (INIS)

Kovacs, Zs.; Hobor, S.; Szabo, P.J.; Lendvai, J.; Zhilyaev, A.P.; Revesz, A.

2007-01-01

Discs of Cu 60 Zr 20 Ti 20 (at.%) composition were produced by high pressure torsion. Radial dependence of the microstructure was monitored by X-ray diffraction and scanning electron microscopy. The inhomogeneous microstructure of the central region consists of particles of about 50 μm and a surrounding matrix. With increasing radius, abrupt transitions take place in the morphology: first the large particles were attrited into lamellae then they transform into a homogeneous microstructure. Microindentation measurements revealed that the hardness showed a significant maximum with refining microstructure

Comprehensive hard materials

CERN Document Server

2014-01-01

Comprehensive Hard Materials deals with the production, uses and properties of the carbides, nitrides and borides of these metals and those of titanium, as well as tools of ceramics, the superhard boron nitrides and diamond and related compounds. Articles include the technologies of powder production (including their precursor materials), milling, granulation, cold and hot compaction, sintering, hot isostatic pressing, hot-pressing, injection moulding, as well as on the coating technologies for refractory metals, hard metals and hard materials. The characterization, testing, quality assurance and applications are also covered. Comprehensive Hard Materials provides meaningful insights on materials at the leading edge of technology. It aids continued research and development of these materials and as such it is a critical information resource to academics and industry professionals facing the technological challenges of the future. Hard materials operate at the leading edge of technology, and continued res...

A comparative evaluation of effect of modern-curing lights and curing modes on conventional and novel-resin monomers

Science.gov (United States)

Roy, Konda Karthik; Kumar, Kanumuru Pavan; John, Gijo; Sooraparaju, Sujatha Gopal; Nujella, Surya Kumari; Sowmya, Kyatham

2018-01-01

Aim: The aim of this study is to compare and to evaluate effect of curing light and curing modes on the nanohybrid composite resins with conventional Bis-GMA and novel tricyclodecane (TCD) monomers. Methodology: Two nanohybrid composites, IPS empress direct and charisma diamond were used in this study. Light-emitting diode (LED)-curing unit and quartz-tungsten-halogen (QTH)-curing unit which were operated into two different modes: continuous and soft start. Based on the composite resin, curing lights, and mode of curing used, the samples were divided into 8 groups. After polymerization, the samples were stored for 48 h in complete darkness at 37°C and 100% humidity. The Vickers hardness (VK) of the surface was determined with Vickers indenter by the application of 200 g for 15 s. Three VK readings were recorded for each sample surface both on top and bottom surfaces. For all the specimens, the three hardness values for each surface were averaged and reported as a single value. The mean VK and hardness ratio were calculated. The depth of cure was assessed based on the hardness ratio. Results: Comparison of mean hardness values and hardness ratios was done using ANOVA with post hoc Tukey's test. Conclusion: Both QTH- and LED-curing units had shown the adequate depth of cure. Soft-start-curing mode in both QTH- and LED-curing lights had effectively increased microhardness than the continuous mode of curing. TCD monomer had shown higher hardness values compared with conventional Bis-GMA-containing resin. PMID:29628651

Superhard MgB sub 2 bulk material prepared by high-pressure sintering

CERN Document Server

Ma, H A; Chen, L X; Zhu, P W; Ren, G Z; Guo, W L; Fu, X Q; Zou Guang Tian; Ren, Z A; Che, G C; Zhao, Z X

2002-01-01

Superhard MgB sub 2 bulk material with a golden metallic shine was synthesized by high-pressure sintering for 8 h at 5.5 GPa and different temperatures. Appropriate pressure and temperature conditions for synthesizing polycrystalline MgB sub 2 with high hardness were investigated. The samples were characterized by means of atomic force microscopy and x-ray diffraction. The Vickers hardness, bulk density, and electrical resistivity were measured at room temperature.

Some aspects of thick, soft nickel plating for end shields of atomic power plants

International Nuclear Information System (INIS)

Krishnaswamy, R.

1987-01-01

Thick (55 Thou) and soft (160 vickers) hardness number nickel plating over SS for RAPP end shields presented unusual problems as the thickness required was extremely large creating adhesion problems and the extremely stringent hardness conditions. A sulfamate bath with nickel anode was found suitable. The problems in thick, soft plating, the chemical and other procedures adopted to monitor the bath and the plated specimen and the other details are presented. (author). 11 refs

Hardness and stability of a carburized surface layer on AISI 316L stainless steel after irradiation in a spallation neutron environment

International Nuclear Information System (INIS)

McClintock, David A.; Hyres, James W.; Vevera, Bradley J.

2014-01-01

The inner surfaces of mercury target vessels at the Spallation Neutron Source (SNS) experience material erosion caused by proton-beam induced cavitation of the liquid mercury. One approach developed and deployed to inhibit erosion of the target vessel material was surface hardening via a proprietary low-temperature carburization treatment, called Kolsterising®, to the target surfaces most susceptible to cavitation-induced erosion. Previous testing has shown that the hardened surface produced by the Kolsterising® treatment can delay the onset of erosion and inhibit erosion once initiated. But the stability of the carbon atmosphere in the treated surface layer after radiation to doses prototypic to the SNS target was unknown. Therefore, as part of the target Post Irradiation Examination program at the SNS, optical microscopy and microhardness testing were performed on material sampled from the first and second operational SNS target vessels. Optical micrographs contained no noticeable precipitation in the super-saturated carbon layer extending into the base material and several micrographs contained evidence of a proposed mechanism for mass wastage from the vessel surface. The hardened layer was characterized using Vickers microhardness testing and results show that the shape of hardness profile of the treated layer corresponded well with known pre-irradiation hardness values, though the microhardness results show some hardening occurred during irradiation. The results suggest that the hardened surface layer produced by the Kolsterising® treatment is stable at the operational temperatures and dose levels experienced by the first and second operational SNS target modules

Microstructure-property relationships and constitutive response of plastically graded case hardened steels

Science.gov (United States)

Klecka, Michael A.

Case hardened materials, popularly used in many demanding engineering applications such as bearings, gears, and wear/impact surfaces, have high surface hardness and a gradient in material properties (hardness, yield strength, etc.) as a function of depth; therefore, they behave as plastically graded materials. In the current study, two different commercially available case carburized steels along with two through hardened steels are characterized to obtain relationships among the volume fraction of subsurface carbides, indentation hardness, elastic modulus, and yield strength as a function of depth. A variety of methods including microindentation, nanoindentation, ultrasonic measurements, compression testing, rule of mixtures, and upper and lower bound models are used to determine the relationships for elastic modulus and compare the experimental results with model predictions. In addition, the morphology, composition, and properties of the carbide particles are also determined. The gradient in hardness with depth in graded materials is commonly determined using microindentation on the cross-section of the material which contains the gradation in microstructure or composition. In the current study, a novel method is proposed to predict the hardness gradient profile using solely surface indentations at a range of loads. The method does not require the graded material to be sectioned, and has practical utility in the surface heat-treatment industry. For a material with a decreasing gradient in hardness, higher indent loads result in a lower measured hardness due to the influence of the softer subsurface layers. A power-law model is presented which relates the measured surface indentation hardness under increasing load to the subsurface gradient in hardness. A coordinated experimental and numerical study is presented to extract the constitutive response of graded materials, utilizing relationships between hardness, plastic deformation, and strain hardening response

Structural, optical, mechanical and density functional theory studies of 1H-pyrazol-2-ium hydrogen oxalate crystal

Energy Technology Data Exchange (ETDEWEB)

Devi, P. Karthiga, E-mail: karthvi19@gmail.com; Venkatachalam, K.

2016-11-01

In the present work, we have grown 1H- pyrazol-2-ium hydrogen oxalate single crystal by slow evaporation solution growth technique. The lattice parameters are determined from single crystal X ray diffraction studies. The functional groups present in the compound are confirmed by Fourier transform infrared spectroscopy. UV-Vis analysis shows that the crystal has a wide transparency window. Vicker's hardness test has been carried out to estimate the stiffness constant, fracture toughness, brittleness index and yield strength of the crystal. Density functional study B3LYP method at 6-31 G (d, p) has been performed to study the optimized structure, HOMO-LUMO energy gap, hyperpolarizability and thermodynamic properties. - Highlights: • The title compound was analyzed using FTIR and UV–Vis spectroscopy. • Mechanical study was carried out using Vicker's hardness test. • Optimized molecular geometry was determined using DFT method. • Hydrogen bonding interaction was studied through NBO analysis.

Boronization and Carburization of Superplastic Stainless Steel and Titanium-Based Alloys

Directory of Open Access Journals (Sweden)

Masafumi Matsushita

2011-07-01

Full Text Available Bronization and carburization of fine-grain superplastic stainless steel is reviewed, and new experimental results for fine grain Ti88.5Al4.5V3Fe2Mo2 are reported. In superplastic duplex stainless steel, the diffusion of carbon and boron is faster than in non-superplastic duplex stainless steel. Further, diffusion is activated by uniaxial compressive stress. Moreover, non-superplastic duplex stainless steel shows typical grain boundary diffusion; however, inner grain diffusion is confirmed in superplastic stainless steel. The presence of Fe and Cr carbides or borides is confirmed by X-ray diffraction, which indicates that the diffused carbon and boron react with the Fe and Cr in superplastic stainless steel. The Vickers hardness of the carburized and boronized layers is similar to that achieved with other surface treatments such as electro-deposition. Diffusion of boron into the superplastic Ti88.5Al4.5V3Fe2Mo2 alloy was investigated. The hardness of the surface exposed to boron powder can be increased by annealing above the superplastic temperature. However, the Vickers hardness is lower than that of Ti boride.

Remember Hard but Think Softly: Metaphorical Effects of Hardness/Softness on Cognitive Functions

Directory of Open Access Journals (Sweden)

Jiushu Xie

2016-09-01

Full Text Available Previous studies have found that bodily stimulation, such as hardness, biases social judgment and evaluation via metaphorical association; however, it remains unclear whether bodily stimulation also affects cognitive functions, such as memory and creativity. The current study used metaphorical associations between hard and rigid and between soft and flexible in Chinese, to investigate whether the experience of hardness affected cognitive functions requiring either rigidity (memory or flexibility (creativity. In Experiment 1, we found that Chinese-speaking participants performed better at recalling previously memorized words while sitting on a hard-surface stool (the hard condition than a cushioned one (the soft condition. In Experiment 2, participants sitting on a cushioned stool outperformed those sitting on a hard-surface stool on a Chinese riddle task, which required creative/flexible thinking, but not on an analogical reasoning task, which required both rigid and flexible thinking. The results suggest the hardness experience affects cognitive functions that are metaphorically associated with rigidity and flexibility. They support the embodiment proposition that cognitive functions and representations could be grounded via metaphorical association in bodily states.

Examination of material manufactured by direct metal laser sintering (DMLS

Directory of Open Access Journals (Sweden)

J. Dobránsky

2015-07-01

Full Text Available This article is concerned with assessing microstructural properties of metal component manufactured by additive DMLS technology. Two series of samples were assessed. The first one was manufactured without heat treatment. Samples in the second series were treated with heat in order to assess increase in hardness and influence on modification of microstructure. Subsequently, values of hardness were measured by Vickers Hardness Test and modification of microstructure was observed by optical microscope. Evaluations were carried out in three planes in order to assess the differences in layering of material during its processing. Differences in values of hardness and microstructural components were discovered by examination of changes in three planes.

Influence of steel composition and plastic deformation on the surface properties induced by low temperature thermochemical processing

DEFF Research Database (Denmark)

Bottoli, Federico

to the formation of a supersaturated solid solution known as expanded austenite, or S-Phase. Expanded austenite is characterized by high hardness, up to 1400 Vickers, and high compressive stresses in the surface region, which result in improved wear and fatigue resistance of the components. Along....../nitrocarburizing on the stress distribution. The experimental techniques applied entail X-ray diffraction (XRD), Glow Discharge Optical EmissionSpectroscopy (GD-OES), Scanning electron microscopy (SEM), light optical microscopy (LOM) and hardness measurement....

MITIGATION OF AGRICULTURAL ENERGY REQUIREMENT IN BANGLADESH USING MICROALGAE PRODUCTION

OpenAIRE

Mohammad Farzid Hasan; Syeda Zohra Halim; Choudhury Mohammad Shahariar; Noor Quddus

2013-01-01

A high quality joint between tool steel and stainless steel alloys is hard to achieve with the conventional welding process. In this study, a new process of joining semi-solid AISI D2 tool steel and AISI 304 stainless steel using a partial remelting method is proposed. Metallographic analysis and Vickers hardness tests were performed. The results obtained from investigating the basic geometries demonstrated a good joining quality that differs from the conventional process of welding or mechan...

The effectiveness of different polymerization protocols for class II composite resin restorations.

NARCIS (Netherlands)

Jong, L.C.G. de; Opdam, N.J.M.; Bronkhorst, E.M.; Roeters, F.J.M.; Wolke, J.G.C.; Geitenbeek, B.

2007-01-01

OBJECTIVES: To investigate the effect of reduced light exposure times on Vickers hardness (VH) of class II composite resin restorations. METHODS: Class II restorations were made in vitro in three 2mm thick increments in a human molar. Two composite resins (Clearfil AP-X; Esthet-X) were polymerized

The effect of adding magnesium oxide on the mechanical properties of the tricalcium phosphate-zirconia composites

Energy Technology Data Exchange (ETDEWEB)

Sallemi, Imen, E-mail: imen.sallemi@hotmail.com; Bouaziz, Jamel; Ben Ayed, Foued

2015-02-01

The effect of magnesium oxide on the mechanical properties of the tricalcium phosphate – 50 wt.% zirconia composites was investigated during a sintering process between 1300 °C and 1400 °C. The characteristics of the samples before and after the sintering process were realized by using the differential thermal analysis, dilatometry, X-ray diffraction, the {sup 31}P magic angle scanning nuclear magnetic resonance, the scanning electron microscope and by considering such mechanical properties as the rupture strength and Vickers hardness. The mechanical performances of the tricalcium phosphate-50 wt.% zirconia composites increased with both the percentage of magnesium oxide and the sintering temperature. At 1400 °C, the mechanical properties of the composites sintered with 10 wt.% magnesium oxide reached their maximum value. Thus, Vickers hardness increased from 554 to 6350 MPa and the rupture strength of the corresponding composites varied from 5.2 to 25 MPa. The increase of the mechanical properties of the samples is due to the formation of both the tetragonal zirconia phase and the liquid phase which helps to fill the pores. The microstructure of needle form is most probably phosphate precipitates which are formed from this liquid phase. Furthermore, the presence of magnesium oxide in the composites prevented the inverse allotropic transformation of zirconia. - Highlights: • We measure the rupture strength and Vickers hardness of bioceramics. • We characterize the effect of MgO on the mechanical properties of the tricalcium phosphate – 50 wt% zirconia composites. • MgO increase the mechanical properties of the composites.

Non-destructive evaluation on mechanical properties of nuclear graphite with porous structure

International Nuclear Information System (INIS)

Shibata, Taiju; Hanawa, Satoshi; Sumita, Junya; Tada, Tatsuya; Sawa, Kazuhiro; Iyoku, Tatsuo

2005-01-01

As a research subjects of 'Research and development for advanced high temperature gas cooled reactor fuels and graphite components,' we started the study of development of non-destructive evaluation methods for mechanical properties of graphite components. The micro-indentation and ultrasonic wave methods are focused to evaluate the degradation of graphite components in VHTR core. For the micro-indentation method, the test apparatus was designed for the indentation test on graphite specimens with some stress levels. It is expected the stress condition is evaluated by the indentation load-depth characteristics and hardness. For the ultrasonic wave method, ultrasonic wave testing machine and probes were prepared for experiments. It is expected that the stress and inner porous conditions are evaluated by the wave propagation characteristics with wave-pore interaction model. R and D plan to develop the non-destructive evaluation method for graphite is presented in this paper. (This study is the result of contract research in the fiscal year of 2004, Research and development for advanced high temperature gas cooled reactor fuels and graphite components,' which is entrusted to the Japan Atomic Energy Research Institute from the Ministry of Education, Culture, Sports, Science and Technology of Japan.) (author)

Micromechanical Characterization of Hydrogels Undergoing Swelling and Dissolution at Alkaline pH

Directory of Open Access Journals (Sweden)

Wei Hu

2017-11-01

Full Text Available The swelling of polyelectrolyte hydrogels usually depends on the pH, and if the pH is high enough degradation can occur. A microindentation device was developed to dynamically test these processes in whey protein isolate hydrogels at alkaline pH 7–14. At low alkaline pH the shear modulus decreases during swelling, consistent with rubber elasticity theory, yet when chemical degradation occurs at pH ≥ 11.5 the modulus decreases quickly and extensively. The apparent modulus was constant with the indentation depth when swelling predominates, but gradients were observed when fast chemical degradation occurs at 0.05–0.1 M NaOH. In addition, these profiles were constant with time when dissolution rates are also constant, the first evidence that a swollen layer with steady state mechanical properties is achieved despite extensive dissolution. At >0.5 M NaOH, we provide mechanical evidence showing that most interactions inside the gels are destroyed, gels were very weak and hardly swell, yet they still dissolve very slowly. Microindentation can provide complementary valuable information to study the degradation of hydrogels.

Hard coal; Steinkohle

Energy Technology Data Exchange (ETDEWEB)

Loo, Kai van de; Sitte, Andreas-Peter [Gesamtverband Steinkohle e.V., Herne (Germany)

2013-04-01

The year 2012 benefited from a growth of the consumption of hard coal at the national level as well as at the international level. Worldwide, the hard coal still is the number one energy source for power generation. This leads to an increasing demand for power plant coal. In this year, the conversion of hard coal into electricity also increases in this year. In contrast to this, the demand for coking coal as well as for coke of the steel industry is still declining depending on the market conditions. The enhanced utilization of coal for the domestic power generation is due to the reduction of the nuclear power from a relatively bad year for wind power as well as reduced import prices and low CO{sub 2} prices. Both justify a significant price advantage for coal in comparison to the utilisation of natural gas in power plants. This was mainly due to the price erosion of the inexpensive US coal which partly was replaced by the expansion of shale gas on the domestic market. As a result of this, the inexpensive US coal looked for an outlet for sales in Europe. The domestic hard coal has continued the process of adaptation and phase-out as scheduled. Two further hard coal mines were decommissioned in the year 2012. RAG Aktiengesellschaft (Herne, Federal Republic of Germany) running the hard coal mining in this country begins with the preparations for the activities after the time of mining.

30 CFR 75.1720-1 - Distinctively colored hard hats, or hard caps; identification for newly employed, inexperienced...

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Distinctively colored hard hats, or hard caps... STANDARDS-UNDERGROUND COAL MINES Miscellaneous § 75.1720-1 Distinctively colored hard hats, or hard caps; identification for newly employed, inexperienced miners. Hard hats or hard caps distinctively different in color...

30 CFR 77.1710-1 - Distinctively colored hard hats or hard caps; identification for newly employed, inexperienced...

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Distinctively colored hard hats or hard caps... Distinctively colored hard hats or hard caps; identification for newly employed, inexperienced miners. Hard hats or hard caps distinctively different in color from those worn by experienced miners shall be worn at...

Mechanical properties of polymer-infiltrated-ceramic-network materials.

Science.gov (United States)

Coldea, Andrea; Swain, Michael V; Thiel, Norbert

2013-04-01

To determine and identify correlations between flexural strength, strain at failure, elastic modulus and hardness versus ceramic network densities of a range of novel polymer-infiltrated-ceramic-network (PICN) materials. Four ceramic network densities ranging from 59% to 72% of theoretical density, resin infiltrated PICN as well as pure polymer and dense ceramic cross-sections were subjected to Vickers Indentations (HV 5) for hardness evaluation. The flexural strength and elastic modulus were measured using three-point-bending. The fracture response of PICNs was determined for cracks induced by Vickers-indentation. Optical and scanning electron microscopy (SEM) was employed to observe the indented areas. Depending on the density of the porous ceramic the flexural strength of PICNs ranged from 131 to 160MPa, the hardness values ranged between 1.05 and 2.10GPa and the elastic modulus between 16.4 and 28.1GPa. SEM observations of the indentation induced cracks indicate that the polymer network causes greater crack deflection than the dense ceramic material. The results were compared with simple analytical expressions for property variation of two phase composite materials. This study points out the correlation between ceramic network density, elastic modulus and hardness of PICNs. These materials are considered to more closely imitate natural tooth properties compared with existing dental restorative materials. Copyright © 2013 Academy of Dental Materials. All rights reserved.

Erosion of heat-treated AISI 4140 steel

Energy Technology Data Exchange (ETDEWEB)

Goretta, K.C. (Materials and Components Tech. Div., Argonne National Lab., IL (United States)); Thompson, A.C. (Materials and Components Tech. Div., Argonne National Lab., IL (United States)); Routbort, J.L. (Materials Science Div., Argonne National Lab., IL (United States))

1993-03-15

Solid-particle erosion was studied on AISI 4140 steel heat treated to have a Vickers hardness (Hv) of 288-650 kg mm[sup -2]. The experiments were conducted in vacuum with 143 [mu]m Al[sub 2]O[sub 3] abrasive impacting at 50-100 m s[sup -1] at an angle of 30 or 90 . Erosion rates were nearly independent of hardness for Hv[<=]365 kg mm[sup -2], but increased with hardness for Hv>365 kg mm[sup -2]. The improved erosion resistances of the softer alloys were attributed to increased ductilities. (orig.). Letter-to-the-editor

Mechanical Properties of Porous Titanium Structure Fabricated by Investment Casting with Pressurization/Depressurization System

International Nuclear Information System (INIS)

Kang, San; Lee, Ji-Woon; Hyun, Soong-Keun; Lee, Byong-Pil; Kim, Myoung-Gyun; Kim, Young-Jig

2014-01-01

A porous titanium structure was fabricated by investment casting with a pressurization/depressurization system, and its mechanical properties were studied. A Micro-Vickers hardness profile revealed that hardness gradually increased from the matrix to the metal/mold interface. A compression test was conducted on a single cell of the porous Ti structure. The theoretical and experimental values of yield strength were in good agreement. Such agreement suggested that the reaction layer did not affect the macro-mechanical properties of the porous Ti structure.

Photon technology. Hard photon technology; Photon technology. Hard photon gijutsu

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-03-01

For the application of photon to industrial technologies, in particular, a hard photon technology was surveyed which uses photon beams of 0.1-200nm in wavelength. Its features such as selective atom reaction, dense inner shell excitation and spacial high resolution by quantum energy are expected to provide innovative techniques for various field such as fine machining, material synthesis and advanced inspection technology. This wavelength region has been hardly utilized for industrial fields because of poor development of suitable photon sources and optical devices. The developmental meaning, usable time and issue of a hard photon reduction lithography were surveyed as lithography in ultra-fine region below 0.1{mu}m. On hard photon analysis/evaluation technology, the industrial use of analysis, measurement and evaluation technologies by micro-beam was viewed, and optimum photon sources and optical systems were surveyed. Prediction of surface and surface layer modification by inner shell excitation, the future trend of this process and development of a vacuum ultraviolet light source were also surveyed. 383 refs., 153 figs., 17 tabs.

Thermodynamic perturbation theory for fused hard-sphere and hard-disk chain fluids

International Nuclear Information System (INIS)

Zhou, Y.; Hall, C.K.; Stell, G.

1995-01-01

We find that first-order thermodynamic perturbation theory (TPT1) which incorporates the reference monomer fluid used in the generalized Flory--AB (GF--AB) theory yields an equation of state for fused hard-sphere (FHS) chain fluids that has accuracy comparable to the GF--AB and GF--dimer--AC theories. The new TPT1 equation of state is significantly more accurate than other extensions of the TPT1 theory to FHS chain fluids. The TPT1 is also extended to two-dimensional fused hard-disk chain fluids. For the fused hard-disk dimer fluid, the extended TPT1 equation of state is found to be more accurate than the Boublik hard-disk dimer equation of state. copyright 1995 American Institute of Physics

Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the JOHN V. VICKERS in the Bering Sea, North Pacific Ocean and South Pacific Ocean from 1992-08-16 to 1992-10-21 (NODC Accession 0115003)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115003 includes chemical, discrete sample, physical and profile data collected from JOHN V. VICKERS in the Bering Sea, North Pacific Ocean and South...

Precipitation hardening and hydrogen embrittlement of aluminum ...

Indian Academy of Sciences (India)

Hydrogen susceptibility of alloy AA7020 was evaluated by slow strain-rate tensile ... high pressures because of the embrittling effect of hydrogen. ... The higher the total Zn + Mg content,. ∗ .... dislocations, leading to a local softening of the slip plane, and thus to ... A Vickers hardness testing machine was used to measure the.

Bulletin of Materials Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

Structural characterization of the glasses was studied with respect to their thermal stability, refractive indices, third order nonlinear optical susceptibility, IR spectra and Vickers hardness. For four different prepared glasses, density in the range from 5.3744 to 6.0731 g.cm-1, the glass transition temperature (g) in the range ...

Wykorzystanie pomiarów mikrotwardości Vickersa do analiz wegla kamiennego pochodzacego z partii F kopalni Borynia-Zofiówka-Jastrzebie, Ruch Zofiówka

Czech Academy of Sciences Publication Activity Database

Godyń, K.; Králová, Lucie

2017-01-01

Roč. 19, č. 1 (2017), s. 25-33 ISSN 1643-1030 Institutional support: RVO:68145535 Keywords : Vickers microhardness * hard coal * Upper Silesian Coal Basin (USCB) Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Mining and mineral processing http://www.img-pan.krakow.pl/index.php/pl/wydawnictwa/prace-img-pan/2016.html

Evaluation of WC-9Co-4Cr laser surface alloyed coatings on stainless steel

CSIR Research Space (South Africa)

Obadele, A

2011-07-01

Full Text Available spectrometer (EDS), while the phase changed were observed using x-ray diffraction (XRD). The surface hardness was determined using the Vickers microhardness tester. The decomposition of WC-9Co-4Cr into W2C, C and W is as a result of low heat of formation of WC...

Hard-on-hard lubrication in the artificial hip under dynamic loading conditions.

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Robert Sonntag

Full Text Available The tribological performance of an artificial hip joint has a particularly strong influence on its success. The principle causes for failure are adverse short- and long-term reactions to wear debris and high frictional torque in the case of poor lubrication that may cause loosening of the implant. Therefore, using experimental and theoretical approaches models have been developed to evaluate lubrication under standardized conditions. A steady-state numerical model has been extended with dynamic experimental data for hard-on-hard bearings used in total hip replacements to verify the tribological relevance of the ISO 14242-1 gait cycle in comparison to experimental data from the Orthoload database and instrumented gait analysis for three additional loading conditions: normal walking, climbing stairs and descending stairs. Ceramic-on-ceramic bearing partners show superior lubrication potential compared to hard-on-hard bearings that work with at least one articulating metal component. Lubrication regimes during the investigated activities are shown to strongly depend on the kinematics and loading conditions. The outcome from the ISO gait is not fully confirmed by the normal walking data and more challenging conditions show evidence of inferior lubrication. These findings may help to explain the differences between the in vitro predictions using the ISO gait cycle and the clinical outcome of some hard-on-hard bearings, e.g., using metal-on-metal.

Remember Hard But Think Softly: Metaphorical Effects of Hardness/Softness on Cognitive Functions

Science.gov (United States)

Xie, Jiushu; Lu, Zhi; Wang, Ruiming; Cai, Zhenguang G.

2016-01-01

Previous studies have found that bodily stimulation, such as hardness biases social judgment and evaluation via metaphorical association; however, it remains unclear whether bodily stimulation also affects cognitive functions, such as memory and creativity. The current study used metaphorical associations between “hard” and “rigid” and between “soft” and “flexible” in Chinese, to investigate whether the experience of hardness affects cognitive functions whose performance depends prospectively on rigidity (memory) and flexibility (creativity). In Experiment 1, we found that Chinese-speaking participants performed better at recalling previously memorized words while sitting on a hard-surface stool (the hard condition) than a cushioned one (the soft condition). In Experiment 2, participants sitting on a cushioned stool outperformed those sitting on a hard-surface stool on a Chinese riddle task, which required creative/flexible thinking, but not on an analogical reasoning task, which required both rigid and flexible thinking. The results suggest the hardness experience affects cognitive functions that are metaphorically associated with rigidity or flexibility. They support the embodiment proposition that cognitive functions and representations can be grounded in bodily states via metaphorical associations. PMID:27672373

Structure-property correlations in nanocrystalline Al-Zr alloy composites

International Nuclear Information System (INIS)

Rittner, M.N.; Argonne National Lab., IL; Weertman, J.R.; Eastman, J.A.

1996-01-01

A study of the structure, grain size stability and Vickers microhardness of nanocrystalline aluminum-zirconium alloy composites was conducted. Samples were synthesized by the inert gas condensation process with electron beam evaporation. Transmission electron microscope examinations of the samples were performed at room and elevated temperatures. The behavior of the microstructures of the samples with time and temperature was investigated as a function of specimen composition. Vickers microhardness data were evaluated at room temperature in as-produced and polished compacted specimens. The local chemical composition of individual microhardness indents and average values of the grain size and porosity level were determined for a number of samples. Correlations among these microstructural variables and hardness were determined using multiple regression techniques

Metallurgical characterization of new palladium-containing cobalt chromium and nickel chromium alloys

Science.gov (United States)

Puri, Raghav

Recently introduced to the market has been an entirely new subclass of casting alloy composition whereby palladium (˜25 wt%) is added to traditional base metal alloys such as CoCr and NiCr. Objectives. The purpose of this study was to evaluate the microstructure and Vickers hardness of two new CoPdCr and one new NiPdCr alloy and compare them to traditional CoCr and NiCr alloys. Methods. The casting alloys investigated were: CoPdCr-A (Noble Crown NF, The Argen Corporation), CoPdCr-I (Callisto CP+, Ivoclar Vivadent), NiPdCr (Noble Crown, Argen), CoCr (Argeloy N.P. Special, Argen), and NiCr (Argeloy N.P. Star, Argen). As-cast cylindrical alloy specimens were mounted in epoxy resin and prepared with standard metallographic procedures, i.e. grinding with successive grades of SiC paper and polishing with alumina suspensions. The alloys were examined with an optical microscope, SEM/EPMA, and XRD to gain insight into their microstructure, composition, and crystal structure. Vickers hardness (VHN) was measured and statistically analyzed by one way ANOVA and Tukey's HSD test (alpha=0.05). Results. Optical microscopy showed a dendritic microstructure for all alloys. The Pd-containing alloys appear to possess a more complex microstructure. SEM/EPMA showed Cr to be rather uniformly distributed in the matrix with palladium tending to be segregated apart from Mo and Ni or Co. Areas of different composition may explain the poor electrochemical results noted in previous studies. XRD suggested the main phase in the Ni-containing solutions was a face centered cubic Ni solid solution, whereas the CoCr exhibited a hexagonal crystal structure that was altered to face centered cubic when Pd was included in the composition. For Vickers hardness, the Co-containing alloys possessed a greater hardness than the Ni-containing alloys. However, the incorporation of Pd in CoCr and NiCr had only a slight effect on microhardness. Conclusion. Overall, the inclusion of palladium increases the

Synthesis and mechanical properties of bulk Al{sub 76}Ni{sub 8}Ti{sub 8}Zr{sub 4}Y{sub 4} alloy fabricated by consolidation of mechanically alloyed amorphous powders

Energy Technology Data Exchange (ETDEWEB)

Wang, Xinfu; Wang, Kun; Li, Zhendong; Wang, Xingfu; Wang, Dan; Han, Fusheng, E-mail: fshan@issp.ac.cn

2015-05-25

Graphical abstract: Different regions indentation morphologies under 50 g load consolidated at 723 K (left), nanohardness of the Al{sub 76}Ni{sub 8}Ti{sub 8}Zr{sub 4}Y{sub 4} alloy as a function consolidation temperature (right). It can be seen from the above figures that the consolidated sample presents white regions, and the microhardness in the white regions is a little lower than the matrix, which could be caused by the difference of the chemical composition and chemical bonding forces between them. Interestingly, the cracks were formed around the indentation periphery in the white regions, which are not shown in the matrix. The nanohardness of the bulk composites increased from 11.16 to 13.27 GPa with the consolidation temperature increasing, mechanical softening was also found in the present alloys. - Highlights: • Bulk amorphous–nanocrystalline Al-based alloys were prepared by HPS process. • The Vickers microhardness of bulk samples is in the range of 945–1177HV0.1. • The nanohardness agrees well with the Vickers hardness testing results. - Abstract: Mechanically alloyed amorphous Al{sub 76}Ni{sub 8}Ti{sub 8}Zr{sub 4}Y{sub 4} (at.%) alloy powder was consolidated by high-pressure sintering process. The influence of the consolidation temperature on the structure and mechanical properties of the consolidated bulk alloys was examined by X-ray diffraction (XRD), Optical microscopy (OM), Scanning electron microscopy (SEM), Vickers Hardness Tester and Nano Indenter. Structural investigations of the bulk materials revealed that most of the amorphous structure was retained after consolidation at 623 K, however, compaction at 723 K and 823 K caused crystallization of the amorphous phase with the appearance of white regions. The results also indicate that application of high pressure affected the crystallization products of the present alloy. Micro mechanical analysis showed that the microhardness of the bulk composites increased from 945HV{sub 0.1} to 1177HV

Concurrent strengthening of ultrafine-grained age-hardenable Al-Mg alloy by means of high-pressure torsion and spinodal decomposition

International Nuclear Information System (INIS)

Tang, Yongpeng; Goto, Wataru; Hirosawa, Shoichi; Horita, Zenji; Lee, Seungwon; Matsuda, Kenji; Terada, Daisuke

2017-01-01

In this study, the age-hardening behavior and precipitate microstructures of severely-deformed and then artificially-aged Al-13.4 wt%Mg alloy has been investigated by Vickers hardness test, X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM) and atom probe tomography (APT). The combined processing of high-pressure torsion (HPT) and aging treatment at a temperature below spinodal lines results in a higher attained hardness of ∼HV296 with an age-hardenability (i.e ΔHV31 ± 2) comparable to that of the undeformed specimen without HPT (i.e. ΔHV33 ± 2). The corresponding TEM microstructures consist of modulated structures associated with spinodal decomposition, and quantitative estimation of the amplitude, as well as the wavelength, of Mg fluctuations was successfully conducted by APT for the first time for this alloy system. The linear relationship between the increment of Vickers hardness and the estimated amplitude of the undeformed specimen supposed that Kato's spinodal-hardening mechanism works even in the HPTed specimen with a high number density of grain boundaries. Therefore, our proposed strategy; i.e. taking advantage of spinodal decomposition, is regarded as a convincing approach to achieving concurrent strengthening by ultrafine-grained and precipitation hardenings for the alloys that decompose via spinodal decomposition.

Microbiological quality of soft, semi-hard and hard cheeses during the shelf-life

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Josip Vrdoljak

2016-03-01

Full Text Available Cheeses as ready-to-eat food should be considered as a potential source of foodborne pathogens, primarily Listeria monocytogenes. The aim of present study was to determine the microbiological quality of soft, semi-hard and hard cheeses during the shelf-life, with particular reference to L. monocytogenes. Five types of cheeses were sampled at different timepoints during the cold storage and analyzed for presence of Salmonella and L. monocytogenes, as well as lactic acid bacteria, Escherichia coli, coagulase-positive staphylococci, yeasts, molds, sulfite-reducing clostridia and L. monocytogenes counts. Water activity, pH and NaCl content were monitored in order to evaluate the possibility of L. monocytogenes growth. Challenge test for L. monocytogenes was performed in soft whey cheese, to determine the growth potential of pathogen during the shelf-life of product. All analyzed cheeses were compliant with microbiological criteria during the shelf-life. In soft cheeses, lactic acid bacteria increased in the course of the shelf-life period (1.2-2.6 log increase, while in semi-hard and hard cheeses it decreased (1.6 and 5.2 log decrease, respectively. Soft cheeses support the growth of L. monocytogenes according to determined pH values (5.8-6.5, water activity (0.99-0.94, and NaCl content (0.3-1.2%. Challenge test showed that L. monocytogenes growth potential in selected soft cheese was 0.43 log10 cfu/g during 8 days at 4°C. Water activity in semi-hard and hard cheeses was a limiting factor for Listeria growth during the shelf-life. Soft, semi-hard and hard cheeses were microbiologically stable during their defined shelf-life. Good manufacturing and hygienic practices must be strictly followed in the production of soft cheeses as Listeria-supporting food and be focused on preventing (recontamination.

Analytical Modeling of Hard-Coating Cantilever Composite Plate considering the Material Nonlinearity of Hard Coating

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Wei Sun

2015-01-01

Full Text Available Due to the material nonlinearity of hard coating, the coated structure produces the nonlinear dynamical behaviors of variable stiffness and damping, which make the modeling of hard-coating composite structure become a challenging task. In this study, the polynomial was adopted to characterize this material nonlinearity and an analytical modeling method was developed for the hard-coating composite plate. Firstly, to relate the hard-coating material parameters obtained by test and the analytical model, the expression of equivalent strain of composite plate was derived. Then, the analytical model of hard-coating composite plate was created by energy method considering the material nonlinearity of hard coating. Next, using the Newton-Raphson method to solve the vibration response and resonant frequencies of composite plate and a specific calculation procedure was also proposed. Finally, a cantilever plate coated with MgO + Al2O3 hard coating was chosen as study case; the vibration response and resonant frequencies of composite plate were calculated using the proposed method. The calculation results were compared with the experiment and general linear calculation, and the correctness of the created model was verified. The study shows the proposed method can still maintain an acceptable precision when the material nonlinearity of hard coating is stronger.

Effect of microstructure on micromechanical performance of dry cortical bone tissues

International Nuclear Information System (INIS)

Yin Ling; Venkatesan, Sudharshan; Kalyanasundaram, Shankar; Qin Qinghua

2009-01-01

The mechanical properties of bone depend on composition and structure. Previous studies have focused on macroscopic fracture behavior of bone. In the present study, we performed microindentation studies to understand the deformation properties and microcrack-microstructure interactions of dry cortical bone. Dry cortical bone tissues from lamb femurs were tested using Vickers indentation with loads of 0.245-9.8 N. We examined the effect of bone microstructure on deformation and crack propagation using scanning electron microscopy (SEM). The results showed the significant effect of cortical bone microstructure on indentation deformation and microcrack propagation. The indentation deformation of the dry cortical bone was basically plastic at any applied load with a pronounced viscoelastic recovery, in particular at lower loads. More microcracks up to a length of approximately 20 μm occurred when the applied load was increased. At loads of 4.9 N and higher, most microcracks were found to develop from the boundaries of haversian canals, osteocyte lacunae and canaliculi. Some microcracks propagated from the parallel direction of the longitudinal interstitial lamellae. At loads 0.45 N and lower, no visible microcracks were observed.

Stress-induced martensitic transformation and ferroelastic deformation adjacent microhardness indents in tetragonal zirconia single crystals

International Nuclear Information System (INIS)

Chien, F.R.; Ubic, F.J.; Prakash, V.; Heuer, A.H.

1998-01-01

The stress-induced tetragonal to monoclinic (t → m) martensitic transformation, stress-induced ferroelastic domain switching, and dislocation slip were induced by Vickers microindentation at elevated temperatures in polydomain single crystals of 3 mol%-Y 2 O 3 -stabilized tetragonal ZrO 2 single crystals (3Y-TZS). Chemical etching revealed traces along t directions adjacent to indentations, and Raman spectroscopy and TEM have shown that these traces are caused by products of the martensitic transformation, i.e. the monoclinic product phase forms primarily as thin, long plates with a habit plane approximately on (bar 301) m . This habit plane and the associated shear strain arising from the transformation, visible in TEM micrographs at the intersection of crystallographically equivalent martensite plates, were successfully predicted using the observed lattice correspondence and the phenomenological invariant plane strain theory of martensitic transformations. The extent of the martensitic transformation increased with increasing temperature from room temperature up to 300 C, but then decreased at higher temperatures. Ferroelastic deformation of tetragonal ZrO 2 has been observed at all temperatures up to 1,000 C. At the highest temperature, only ferroelastic domain switching and dislocation slip occurred during indentation-induced deformation

The technology development for surveillance test of RPV materials 2

International Nuclear Information System (INIS)

Chang, Kee Ok; Lee, Sam Lai; Kim, Byoung Chul; Choi, Sun Pil; Choi, Kwen Jai

1998-12-01

Irradiation-induced changes in mechanical properties and magnetic parameters were measured and compared to explore possible correlations for Mn-Mo-Ni low alloy steel surveillance specimens which were irradiated to a neutron fluence of 2.4 x 10 1 9n/cm 2 (E≥1.0 MeV) in a typical pressurized water reactor environment at about 288 deg C. For mechanical property parameters, microvickers hardness, tensile and Charpy impact test were performed and Barkhausen Noise(BN) amplitude, coercivity, maximum induction were measured for magnetic parameters, respectively. Results of mechanical property measurements showed an increase in yield and tensil strength, microvickers hardness 41J indexed RT NDT and a decrease in upper shelf energy irrespective of base and weld metals. In the case of magnetic measurements, it is found that magnetic remanence, BN amplitude, BN energy have dropped significantly but coercivity has increased rapidly after irradiation. For isothermally heat treated condition of irradiated specimen, BN energy has increased while Vickers microhardness has decreased. Results of BNE and Vickers microhardness are reversed to the results on irradiated condition. All these consistent changes in magnetic parameter and Vickers microhardness measurement, which are thought to be resulted from the interaction between irradiation-induced defects and dislocation, and magnetic domain, respectively, show a possibility that magnetic measurement may be used to the evaluation of material degradation and recovery due to neutron irradiation and heat treatment, respectively, if a relevant large database is prepared. (author). 49 refs., 7 tabs., 23 figs

Microstructure and kinetics of a functionally graded NiTi-TiC x composite produced by combustion synthesis

International Nuclear Information System (INIS)

Burkes, Douglas E.; Moore, John J.

2007-01-01

Production of a NiTi-TiC x functionally graded material (FGM) composite is possible through use of a combustion synthesis (CS) reaction employing the propagating mode (SHS). The NiTi-TiC x FGM combines the well-known and understood superelastic and shape memory capabilities of NiTi with the high hardness, wear and corrosion resistance of TiC x . The material layers were observed as functionally graded both in composition and porosity with distinct interfaces, while still maintaining good material interaction and bonding. XRD of the FGM composite revealed the presence of TiC x with equi-atomic NiTi and minor NiTi 2 and NiTi 3 phases. The TiC x particle size decreased with increasing NiTi content. Microindentation performed across the length of the FGM revealed a decrease in hardness as the NiTi content increased

Alpha radiation and in-pile annealing effects on the fracture properties of a sintered alumino borosilicate glass

International Nuclear Information System (INIS)

Bevilacqua, Arturo M.; Prado, Miguel O.; Messi de Bernasconi, Norma B.; Heredia, Arturo D.; Sanfilippo, Miguel

1999-01-01

The alpha radiation and the in-pile during irradiation effects on the hardness, the crack nucleation and the fracture toughness of the German alumino borosilicate glass SG7 were investigated by using the Vickers indentation. Cold pressed and sintered samples were irradiated with thermal neutrons, in the Argentine nuclear reactors RA-3 and RA-6, to produce alpha particles in the whole volume of the glass by means of the (n, alpha)-reaction with B-10. The Vickers hardness, the crack nucleation, as 50 percent fracture probability load, plotted as the Weibull's fracture probability distribution function and the fracture toughness, as critical stress intensity factor K Ic , were correlated to the four cumulative disintegration values. It was ascertained that: a) the Vickers hardness decreases from 5.6 GPa for the non-irradiated sample up to 4.7 GPa for the sample irradiated 70 h at the lower neutron flux (4.0 x 10 - sup 18 - alpha disintegration per cm - sup 3 -), b) the 50 % fracture probability load increases from 1.4 N for the non-irradiated sample up to 4.7 g for the sample irradiated 22 h at the higher flux (6.8 x 10 - sup 18 - alpha disintegration per cm - sup 3 -), and c) the stress intensity factor increases from 0.80 MPa.m - sup 1/2 - for the non irradiated sample up to 0.86 MPa.m - sup 1/2 - for the sample mentioned in b). The in-pile annealing was analyzed by comparing the crack nucleation after irradiation with data obtained by heavy ion irradiation followed by thermal annealing. Results for the SG7 glass were compared to those for soda-lime and borosilicate glasses. (author)

Textural and morphological studies on zinc–iron alloy electrodeposits

Indian Academy of Sciences (India)

ness of the coating was measured in Vicker's hard- ness number (VHN) by static indentation method, using. Leco microhardness tester (Model M 400) at a given load for 15 seconds time duration. X-ray diffraction pat- terns were taken by using JEOL PANalytical, X' per. PRO model. Samples were scanned between 20. ◦ and.

Chemical hardness and density functional theory

Indian Academy of Sciences (India)

Unknown

RALPH G PEARSON. Chemistry Department, University of California, Santa Barbara, CA 93106, USA. Abstract. The concept of chemical hardness is reviewed from a personal point of view. Keywords. Hardness; softness; hard & soft acids bases (HSAB); principle of maximum hardness. (PMH) density functional theory (DFT) ...

Hardness variability in commercial technologies

International Nuclear Information System (INIS)

Shaneyfelt, M.R.; Winokur, P.S.; Meisenheimer, T.L.; Sexton, F.W.; Roeske, S.B.; Knoll, M.G.

1994-01-01

The radiation hardness of commercial Floating Gate 256K E 2 PROMs from a single diffusion lot was observed to vary between 5 to 25 krad(Si) when irradiated at a low dose rate of 64 mrad(Si)/s. Additional variations in E 2 PROM hardness were found to depend on bias condition and failure mode (i.e., inability to read or write the memory), as well as the foundry at which the part was manufactured. This variability is related to system requirements, and it is shown that hardness level and variability affect the allowable mode of operation for E 2 PROMs in space applications. The radiation hardness of commercial 1-Mbit CMOS SRAMs from Micron, Hitachi, and Sony irradiated at 147 rad(Si)/s was approximately 12, 13, and 19 krad(Si), respectively. These failure levels appear to be related to increases in leakage current during irradiation. Hardness of SRAMs from each manufacturer varied by less than 20%, but differences between manufacturers are significant. The Qualified Manufacturer's List approach to radiation hardness assurance is suggested as a way to reduce variability and to improve the hardness level of commercial technologies

Microstructure and deuterium retention after ion irradiation of W–Lu{sub 2}O{sub 3} composites

Energy Technology Data Exchange (ETDEWEB)

Lin, Jin–Shan [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Luo, Lai–Ma, E-mail: luolaima@126.com [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Laboratory of Nonferrous Metal Material and Processing Engineering of Anhui Province, Hefei 230009 (China); Xu, Qiu [Research Reactor Institute, Kyoto University, Osaka-fu 590-0494 (Japan); Zan, Xiang; Zhu, Xiao–Yong [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Laboratory of Nonferrous Metal Material and Processing Engineering of Anhui Province, Hefei 230009 (China); Wu, Yu–Cheng, E-mail: ycwu@hfut.edu.cn [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Laboratory of Nonferrous Metal Material and Processing Engineering of Anhui Province, Hefei 230009 (China)

2017-07-15

W–3Lu{sub 2}O{sub 3} composites were prepared by mechanical milling and spark plasma sintering. The obtained composites were subjected to He{sup +} irradiation experiments. The irradiated samples were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and measurement of Vickers hardness. Thermal desorption spectroscopy analysis was performed to analyze the samples at different damage levels after Fe{sup 2+} and D{sup +} irradiation. Results showed varied degrees of He{sup +} damage under different energies. Fuzz structures were observed on the surface of the material after irradiation. TEM results indicated that the existence of these fuzz structures was related to the formation of He bubbles. Amorphous, polycrystalline, and γ-W phases formed in areas where He bubbles existed. The measured Vickers hardness proved that radiation hardening occurred after irradiation. After Fe{sup 2+} irradiation at different damage levels, the total retained deuterium amount of W–3Lu{sub 2}O{sub 3} and pure W differed, and the impact of Fe{sup 2+} radiation for deuterium retention on pure tungsten was greater.

Microstructure and deuterium retention after ion irradiation of W–Lu2O3 composites

International Nuclear Information System (INIS)

Lin, Jin–Shan; Luo, Lai–Ma; Xu, Qiu; Zan, Xiang; Zhu, Xiao–Yong; Wu, Yu–Cheng

2017-01-01

W–3Lu 2 O 3 composites were prepared by mechanical milling and spark plasma sintering. The obtained composites were subjected to He + irradiation experiments. The irradiated samples were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and measurement of Vickers hardness. Thermal desorption spectroscopy analysis was performed to analyze the samples at different damage levels after Fe 2+ and D + irradiation. Results showed varied degrees of He + damage under different energies. Fuzz structures were observed on the surface of the material after irradiation. TEM results indicated that the existence of these fuzz structures was related to the formation of He bubbles. Amorphous, polycrystalline, and γ-W phases formed in areas where He bubbles existed. The measured Vickers hardness proved that radiation hardening occurred after irradiation. After Fe 2+ irradiation at different damage levels, the total retained deuterium amount of W–3Lu 2 O 3 and pure W differed, and the impact of Fe 2+ radiation for deuterium retention on pure tungsten was greater.

Influence of polymerization time and depth of cure of resin composites determined by Vickers hardness

Directory of Open Access Journals (Sweden)

Marco Lombardini

2012-01-01

Conclusion: Among the materials tested, the nanofilled and the nanohybrid resin composites were rather insensible to thickness variations. Miicrohybrid composites, instead, had features different from one another.

Bearing assembly and the like for use in corrosive and non-corrosive atmospheres

International Nuclear Information System (INIS)

Mashburn, D.N.; Woodall, H.C.; Wright, R.R.

1979-01-01

This invention relates to a novel machine element characterized by mutually rubbing surfaces which are composed of dissimilar materials having high hardness, a low coefficient of friction, and resistance to corrosion by halogen-containing atmospheres. As exemplified by the preferred embodiment for use in gaseous UF 6 , the rubbing surfaces are chemically deposited nickel and anodized aluminum. These surfaces permit jam-free operation despite long-term exposure to UF 6 . Preferably, both surfaces have a hardness of at least about 500 HV 100 on the Vickers hardness scale, and preferably the anodized-aluminum surface is of type having comparatively little tendency to sorb uranium hexafluoride

Fabrication of Al-20 wt%Si powder using scrap Si by ultra high-energy milling process

Energy Technology Data Exchange (ETDEWEB)

Kang, Won-Kyung [Division of Advanced Materials Engineering and Institute for Rare Metals, Kongju National University, 275, Budae-dong, Cheonan, Chungnam 330-717 (Korea, Republic of); Y Latin-Small-Letter-Dotless-I lmaz, Fikret [Department of Physics, Faculty of Art and Science, Gaziosmanpasa University, Tasliciftlik Campus, 60240 Tokat (Turkey); Kim, Hyo-Seob; Koo, Jar-Myung [Division of Advanced Materials Engineering and Institute for Rare Metals, Kongju National University, 275, Budae-dong, Cheonan, Chungnam 330-717 (Korea, Republic of); Hong, Soon-Jik, E-mail: hongsj@kongju.ac.kr [Division of Advanced Materials Engineering and Institute for Rare Metals, Kongju National University, 275, Budae-dong, Cheonan, Chungnam 330-717 (Korea, Republic of)

2012-09-25

Highlights: Black-Right-Pointing-Pointer High energy ball milling process has been successfully employed to produce Al-20Si alloy using scrap Si powders. Black-Right-Pointing-Pointer Fully finer and homogenous structure could be achieved after 60 min of milling time. Black-Right-Pointing-Pointer Si particles were not dissolved but uniformly dispersed in the Al matrix in a milled state. Black-Right-Pointing-Pointer The hardness of as-milled Al-20Si powder increased steadily with the increase of milling time. Black-Right-Pointing-Pointer Grain size and dispersion strengthening are two mechanisms being responsible for hardness increment. - Abstract: In this study, microstructural evolution and mechanical properties of Al-20 wt%Si and pure Al powders fabricated by ultra high-energy ball milling technique were investigated as a function of milling time. The microstructure and mechanical properties of the as-milled powders were examined by scanning electron microscope (SEM), energy dispersive spectrometry (EDS), X-ray diffractometer (XRD) and Vickers hardness tester. SEM observation showed that the particle size increased at an early stage of milling, and then decreased drastically with further milling. XRD and cross-sectional EDS-mapping analyses revealed that Si particles were not dissolved but uniformly dispersed in the Al matrix in a milled state. Vickers hardness of both pure Al and Al-Si powder increases with milling time, which attributes to the grain size strengthening and dispersion strengthening.

Zirconia toughened mica glass ceramics for dental restorations.

Science.gov (United States)

Gali, Sivaranjani; K, Ravikumar; Murthy, B V S; Basu, Bikramjit

2018-03-01

The objective of the present study is to understand the role of yttria stabilized zirconia (YSZ) in achieving the desired spectrum of clinically relevant mechanical properties (hardness, elastic modulus, fracture toughness and brittleness index) and chemical solubility of mica glass ceramics. The glass-zirconia mixtures with varying amounts of YSZ (0, 5, 10, 15 and 20wt.%) were ball milled, compacted and sintered to obtain pellets of glass ceramic-YSZ composites. Phase analysis was carried out using X-ray diffraction and microstructural characterization with SEM revealed the crystal morphology of the composites. Mechanical properties such as Vickers hardness, elastic modulus, indentation fracture toughness and chemical solubility were assessed. Phase analysis of sintered pellets of glass ceramic-YSZ composites revealed the characteristic peaks of fluorophlogopite (FPP) and tetragonal zirconia. Microstructural investigation showed plate and lath-like interlocking mica crystals with embedded zirconia. Vickers hardness of 9.2GPa, elastic modulus of 125GPa, indentation toughness of 3.6MPa·m 1/2 , and chemical solubility of 30μg/cm 2 (well below the permissible limit) were recorded with mica glass ceramics containing 20wt.% YSZ. An increase in hardness and toughness of the glass ceramic-YSZ composites with no compromise on their brittleness index and chemical solubility has been observed. Such spectrum of properties can be utilised for developing a machinable ceramic for low stress bearing inlays, onlays and veneers. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Comparative Microstructural and Wettability Studies of 63sn-37pb ...

African Journals Online (AJOL)

The respective wettability values (in percentage) of the total area of the copper grid covered by the molten solder are: 8.3%, and 8.6% The alloy also have the following Vicker's Hardness Values of 18.58VHN and 16.32VHN. The microstructures of the developed alloys were studied and analyzed. The alloy's microstructures ...

Studying Hardness Meter Spring Strength to Understand Hardness Distribution on Body Surfaces.

Science.gov (United States)

Arima, Yoshitaka

2017-10-01

For developing a hardness multipoint measurement system for understanding hardness distribution on biological body surfaces, we investigated the spring strength of the contact portion main axis of a biological tissue hardness meter (product name: PEK). We measured the hardness of three-layered sheets of six types of gel sheets (90 mm × 60 mm × 6 mm) constituting the acupuncture practice pads, with PEK measurements of 1.96 N, 2.94 N, 3.92 N, 4.90 N, 5.88 N, 6.86 N, 7.84 N, 8.82 N, and 9.81 N of the main axis spring strength. We obtained measurements 10 times for the gel sheets and simultaneously measured the load using a digital scale. We measured the hardness distribution of induration embedded and breast cancer palpation models, with a main axis with 1.96 N, 4.90 N, and 9.81 N spring strengths, to create a two-dimensional Contour Fill Chart. Using 4.90 N spring strength, we could obtain measurement loads of ≤3.0 N, and the mean hardness was 5.14 mm. This was close to the median of the total measurement range 0.0-10.0 mm, making the measurement range the largest for this spring strength. We could image the induration of the induration-embedded model regardless of the spring strength. Overall, 4.90 N spring strength was best suited for imaging cancer in the breast cancer palpation model. Copyright © 2017. Published by Elsevier B.V.

Optimization of process parameters in welding of dissimilar steels using robot TIG welding

Science.gov (United States)

Navaneeswar Reddy, G.; VenkataRamana, M.

2018-03-01

Robot TIG welding is a modern technique used for joining two work pieces with high precision. Design of Experiments is used to conduct experiments by varying weld parameters like current, wire feed and travelling speed. The welding parameters play important role in joining of dissimilar stainless steel SS 304L and SS430. In this work, influences of welding parameter on Robot TIG Welded specimens are investigated using Response Surface Methodology. The Micro Vickers hardness tests of the weldments are measured. The process parameters are optimized to maximize the hardness of the weldments.

Development of a dispersion strengthened copper alloy using a MA-HIP method

Directory of Open Access Journals (Sweden)

T. Yamada

2016-12-01

Full Text Available A new Cu-Al alloy was fabricated by a MA-HIP method for application to the heat sink materials of divertors. With the increase in MA time, the grain size and Vickers hardness decreased and increased, respectively. At MA time of 32hrs, the hardness of the alloy was comparable to that of Glidcop® although the grain size was much larger. X-ray diffractometry, electrical resistivity measurements and STEM-EDS analyses suggested precipitation of Al-rich phase by MA for 32hrs followed by HIP.

Induced spherococcoid hard wheat

International Nuclear Information System (INIS)

Yanev, Sh.

1981-01-01

A mutant has been obtained - a spheroccocoid line -through irradiation of hard wheat seed with fast neutrons. It is distinguished by semispherical glumes and smaller grain; the plants have low stem with erect leaves but with shorter spikes and with lesser number of spikelets than those of the initial cultivar. Good productive tillering and resistance to lodging contributed to 23.5% higher yield. The line was superior to the standard and the initial cultivars by 14.2% as regards protein content, and by up to 22.8% - as to flour gluten. It has been successfully used in hybridization producing high-yielding hard wheat lines resistant to lodging, with good technological and other indicators. The possibility stated is of obtaining a spherococcoid mutant in tetraploid (hard) wheat out of the D-genome as well as its being suited to hard wheat breeding to enhance protein content, resistance to lodging, etc. (author)

2TB hard disk drive

CERN Multimedia

This particular object was used up until 2012 in the Data Centre. It slots into one of the Disk Server trays. Hard disks were invented in the 1950s. They started as large disks up to 20 inches in diameter holding just a few megabytes (link is external). They were originally called "fixed disks" or "Winchesters" (a code name used for a popular IBM product). They later became known as "hard disks" to distinguish them from "floppy disks (link is external)." Hard disks have a hard platter that holds the magnetic medium, as opposed to the flexible plastic film found in tapes and floppies.

Janka hardness using nonstandard specimens

Science.gov (United States)

David W. Green; Marshall Begel; William Nelson

2006-01-01

Janka hardness determined on 1.5- by 3.5-in. specimens (2×4s) was found to be equivalent to that determined using the 2- by 2-in. specimen specified in ASTM D 143. Data are presented on the relationship between Janka hardness and the strength of clear wood. Analysis of historical data determined using standard specimens indicated no difference between side hardness...

Determining the Effect of Material Hardness During the Hard Turning of AISI4340 Steel

Science.gov (United States)

Kambagowni, Venkatasubbaiah; Chitla, Raju; Challa, Suresh

2018-05-01

In the present manufacturing industries hardened steels are most widely used in the applications like tool design and mould design. It enhances the application range of hard turning of hardened steels in manufacturing industries. This study discusses the impact of workpiece hardness, feed and depth of cut on Arithmetic mean roughness (Ra), root mean square roughness (Rq), mean depth of roughness (Rz) and total roughness (Rt) during the hard turning. Experiments have been planned according to the Box-Behnken design and conducted on hardened AISI4340 steel at 45, 50 and 55 HRC with wiper ceramic cutting inserts. Cutting speed is kept constant during this study. The analysis of variance was used to determine the effects of the machining parameters. 3-D response surface plots drawn based on RSM were utilized to set up the input-output relationships. The results indicated that the feed rate has the most significant parameter for Ra, Rq and Rz and hardness has the most critical parameter for the Rt. Further, hardness shows its influence over all the surface roughness characteristics.

Tribological Behaviour of Ti:Ta-DLC Films Under Different Tribo-Test Conditions

Science.gov (United States)

Efeoglu, İhsan; Keleş, Ayşenur; Totik, Yaşar; Çiçek, Hikmet; Emine Süküroglu, Ebru

2018-01-01

Diamond-like carbon (DLC) films are suitable applicants for cutting tools due to their high hardness, low friction coefficient and wear rate. Doping metals in DLC films have been improved its tribological properties. In this study, titanium and tantalum doped hydrogenated DLC films were deposited by closed-field unbalanced magnetron sputtering system onto M2 high speed steels in Ar/N2/C2H2 atmosphere. The friction and wear properties of Ti:Ta-DLC film were investigated under different tribo-test conditions including in atmospheric pressure, distilled water, commercial oil and Ar atmosphere. The coated specimens were characterized by SEM and X-ray diffraction techniques. The bonding state of C-C (sp3) and C=C (sp2) were obtained with XPS. The tribological properties of Ti:Ta-DLC were investigated with pin-on-disc wear test. Hardness measurements performed by micro-indentation. Our results suggest that Ti:Ta-doped DLC film shows very dense columnar microstructure, high hardness (38.2 GPa) with low CoF (µ≈0.02) and high wear resistance (0.5E-6 mm3/Nm).

Resistência química de vitro-cerâmicos pertencentes a sistemas Li2O-ZrO2-BaO-SiO2 frente ao tratamento com soluções ácidas e básicas Chemical durability of the Li2O-ZrO2-BaO-SiO2 glass-ceramic treated with acidic and basic solution

Directory of Open Access Journals (Sweden)

Silvia Denofre de Campos

2002-05-01

Full Text Available The chemical durability of the Li2O-ZrO2-BaO-SiO2 system was examined by determination of the Vickers hardness. The dependence of hardness and of the chemical resistance with BaO addition was investigated. The experimental results indicate that the hardness increases with the BaO content. The samples surface's morphology submitted to the chemical treatment in acidic (H2SO4 and basic (KOH solution was accompanied by scanning electron microscopy. The chemical durability of the materials with BaO showed better than the glass ceramic without this content. These materials treated with H2SO4 solution showed a preferential attack to the silica rich sites.

On scale dependence of hardness

International Nuclear Information System (INIS)

Shorshorov, M.Kh.; Alekhin, V.P.; Bulychev, S.I.

1977-01-01

The concept of hardness as a structure-sensitive characteristic of a material is considered. It is shown that in conditions of a decreasing stress field under the inventor the hardness function is determined by the average distance, Lsub(a), between the stops (fixed and sessile dislocations, segregation particles, etc.). In the general case, Lsub(a) depends on the size of the impression and explains the great diversity of hardness functions. The concept of average true deformation rate on depression is introduced

Effect of light intensity and irradiation time on the polymerization process of a dental composite resin

Directory of Open Access Journals (Sweden)

Discacciati José Augusto César

2004-01-01

Full Text Available Polymerization shrinkage is a critical factor affecting the longevity and acceptability of dental composite resins. The aim of this work was to evaluate the effect of light intensity and irradiation time on the polymerization process of a photo cured dental composite resin by measuring the Vickers hardness number (VHN and the volumetric polymerization shrinkage. Samples were prepared using a dental manual light-curing unit. The samples were submitted to irradiation times of 5, 10, 20 and 40 s, using 200 and 400 mW.cm-2 light intensities. Vickers hardness number was obtained at four different moments after photoactivation (immediate, 1 h, 24 h and 168 h. After this, volumetric polymerization shrinkage values were obtained through a specific density method. The values were analyzed by ANOVA and Duncan's (p = 0.05. Results showed increase in hardness values from the immediate reading to 1 h and 24 h readings. After 24 h no changes were observed regardless the light intensities or activation times. The hardness values were always smaller for the 200 mW.cm-2 light intensity, except for the 40 s irradiation time. No significant differences were detected in volumetric polymerization shrinkage considering the light intensity (p = 0.539 and the activation time (p = 0.637 factors. In conclusion the polymerization of the material does not terminate immediately after photoactivation and the increase of irradiation time can compensate a lower light intensity. Different combinations between light intensity and irradiation time, i.e., different amounts of energy given to the system, have not affected the polymerization shrinkage.

The Properties of Sintered Calcium Phosphate with [Ca]/[P] = 1.50

Directory of Open Access Journals (Sweden)

Moo-Chin Wang

2012-10-01

Full Text Available In order to obtain the properties of the sintered as-dried calcium phosphate with [Ca]/[P] = 1.50, the characteristics of sintered pellets have been investigated using X-ray diffraction (XRD, inductively coupled plasma-mass spectrometry (ICP-MS, Fourier-transform infrared (FT-IR spectra, Vickers hardness indentation and scanning electron microscopy (SEM. When the pellet samples were sintered between 700 °C and 1200 °C for 4 h, the hydroxyapatite (Ca10(PO46(OH2, HA still maintained the major phase, accompanied with the rhenanite (NaCaPO4 as the secondary phase and β-tricalcium phosphate (β-Ca3(PO42, β-TCP as the minor phases. In addition, the HA partially transformed to α-tricalcium phosphate (α-Ca3(PO42, α-TCP and tetracalcium phosphate (Ca4(PO42O, TTCP, when the pellet samples were sintered at 1300 °C and 1400 °C, respectively, for 4 h. The maximum density and Vickers Hardness (HV of sintered pellet samples were 2.85 g/cm3 (90.18% theoretical density (T.D. and 407, which appeared at 1200 °C and 900 °C, respectively.

Effect of an Intermediate Heat-treatment on a Change of the Corrosion Resistance and Hardness of a HANA-4 Outer Strip

International Nuclear Information System (INIS)

Lee, Myung Ho; Jung, Yang Il; Park, Sang Yoon; Choi, Byoung Kwon; Park, Jeong Yong; Jeong, Yong Hwan; Eom, Kyong Bo; Park, Nam Gyu; Lim, Yoon Soo

2008-01-01

KAERI (Korea Atomic Energy Research Institute) in collaboration with KNF (Korea Nuclear Fuel) undertook some researches on the applicability of HANA-4 and HANA-6 alloys for the spacer grid for a PWR (Pressurized Water Reactor) nuclear fuel. As a part of the research, KAERI studied the effect of the final heat-treatment on the mechanical and corrosion properties of a HANA-4 inner strip. The strip was manufactured with a sheet which had been intermediately heat-treated at about 580 .deg. C for 2.5-4 hours after each cold rolling before being processed into the final strip product. It was mentioned that the process with the intermediate heat treatment needed reviewing to establish an improved manufacturing process for the cold rolling. So, this work tried to check the effect of an intermediate heat-treatment on the properties of a HANA-4 strip using a specimen that was taken from a second hot rolled material before a cold-rolling. The manufacturing processes, with three different kinds of annealings, were introduced to investigate the applicable intermediate heat-treatment process. After all the cold-rolling processes, the Vickers hardness was measured for the final annealed specimens and 60 days of corrosion tests were carried out to check on the effect of the intermediate heat-treatment. Finally, an appropriate intermediate heat-treatment was proposed to improve the manufacturability of the HANA-4 strip

Hard-hat day

CERN Multimedia

2003-01-01

CERN will be organizing a special information day on Friday, 27th June, designed to promote the wearing of hard hats and ensure that they are worn correctly. A new prevention campaign will also be launched.The event will take place in the hall of the Main Building from 11.30 a.m. to 2.00 p.m., when you will be able to come and try on various models of hard hat, including some of the very latest innovative designs, ask questions and pass on any comments and suggestions.

Structure and properties of nanophase TiO2

International Nuclear Information System (INIS)

Siegel, R.W.; Hahn, H.; Ramasamy, S.; Zongquan, Li; Ting, Lu; Gronsky, R.

1987-07-01

Ultrafine-grained, nanophase samples of TiO 2 (rutile) were synthesized by the gas-condensation method and subsequent in-situ compaction, and then studied by transmission electron microscopy, Vickers hardness measurements, and positron annihilation spectroscopy as a function of sintering temperature. The nanophase compacts densified rapidly above 500 0 C, with only a small increase in grain size. The hardness values obtained by this method are comparable to or greater than coarser-grained compacts, but at temperatures 400 to 600 0 C lower than conventional sintering temperatures and without the need for sintering aids. 11 refs., 3 figs

Changes in the tribological behavior of an epoxy resin by incorporating CuO nanoparticles and PTFE microparticles

DEFF Research Database (Denmark)

Larsen, Thomas Ricco Ølholm; Andersen, Tom Løgstrup; Thorning, Bent

2008-01-01

by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), which show a relatively good dispersion of both kinds of particles. Differential scanning calorimetry (DSC) and Vickers hardness measurements show no clear changes in glass transition temperature or hardness as a function...... of the composites using a smoother counterface. This gives rise to significantly less wear, which for composites without PTFE is attributed to formation of a protective transfer film. At a pv condition of 1.16 MPa, 1.0 m1s the following is found: composites without PTFE generally show an unsteady behavior with high...

Spectroscopic and mechanical studies on the Fe-based amorphous alloy 2605SA1

International Nuclear Information System (INIS)

Cabral P, A.; Garcia S, I.; Contreras V, J. A.; Garcia S, F.; Nava, N.

2010-01-01

The Vickers micro-hardness of this alloy was unusually dependent on the heat treatment from 300 to 634 K, inferring important micro-structural changes and the presence of amorphous grains before its phase transition. Once the alloy is crystallized, the micro-hardness is characteristic of a brittle alloy, the main problem of these alloys. Within the amorphous state, other properties like free-volume, magnetic states and Fe-Fe distances were followed by Positron annihilation lifetime spectroscopy and Moessbauer spectroscopy, respectively, to analyze those micro-structural changes, thermally induced, which are of paramount interest to understand their brittleness problem. (Author)

Effect of Sn addition on phases stability and mechanical properties of aged Ti-10Mo Alloy

International Nuclear Information System (INIS)

Cardoso, F.F.; Lopes, E.S.N.; Cremasco, A.; Contieri, R.J.; Mello, M.G.; Caram, R.

2010-01-01

Nowadays there is considerable effort in order to develop new titanium alloys using non-toxic elements such as Mo and Sn. This work deals with the alloys Ti-Mo-Sn. The samples were melted, homogenized and hot swaged. Afterwards they were solubilized and water quenched. The alloys were also aged at several temperatures Characterization involved determination of Young's modulus, hardness, X-ray diffraction and optical microscopy. The X-ray diffraction indicated the presence of athermal and isothermal ω phase for Ti-10Mo alloy. One also evidenced that the Vickers hardness varies with the temperature and the time of aging heat treatment. (author)

Dynamic characteristics of automotive steel sheets

Directory of Open Access Journals (Sweden)

M. Mihaliková

2016-10-01

Full Text Available The aim of this experimental research was to perform an analysis of deformation characteristics on two different types of steel: IF steel, and micro-alloyed steel were used automotive industry. For that purpose changes of properties of these materials were carried out by static 10-3 · s-1 and dynamic 103 · s-1 strain rate assess its plastic properties. Vickers micro hardness test was carried out by the static and dynamic loading condition and describes different hardness distribution. The higher strain hardening of materials was obtained too that was confirmed by distribution of dislocations.

Surface characterization of TiNi deformed by high-pressure torsion

Energy Technology Data Exchange (ETDEWEB)

Awang Shri, Dayangku Noorfazidah [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan); Structural Materials Unit, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047 (Japan); Tsuchiya, Koichi, E-mail: tsuchiya.koichi@nims.go.jp [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan); Structural Materials Unit, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047 (Japan); Yamamoto, Akiko [Biomaterials Unit, International Center for Material Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044 (Japan)

2014-01-15

Effect of grain refinements and amorphization by high-pressure torsion (HPT) on surface chemistry was investigated on TiNi. X-ray diffraction and micro-Vickers tests were used to check the phase changes and hardness before and after HPT. X-ray photoelectron spectroscopy was used to observe the changes in the natural passive film formation on the surface. Phase analysis reveals the change of crystalline TiNi to nanostructured one with increased hardness with straining by HPT. Grain refinement and amorphization caused by HPT reduce the amount of metallic Ni in the passive films and also increase the thickness of the film.

Spectroscopic and mechanical studies on the Fe-based amorphous alloy 2605SA1

Energy Technology Data Exchange (ETDEWEB)

Cabral P, A.; Garcia S, I. [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Contreras V, J. A.; Garcia S, F. [Universidad Autonoma del Estado de Mexico, Facultad de Ciencias, El Cerrillo Piedras Blancas, Toluca, Estado de Mexico (Mexico); Nava, N., E-mail: agustin.cabral@inin.gob.m [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas No. 152, Col. San Bartolo Atepehuacan, 07730 Mexico D. F. (Mexico)

2010-07-01

The Vickers micro-hardness of this alloy was unusually dependent on the heat treatment from 300 to 634 K, inferring important micro-structural changes and the presence of amorphous grains before its phase transition. Once the alloy is crystallized, the micro-hardness is characteristic of a brittle alloy, the main problem of these alloys. Within the amorphous state, other properties like free-volume, magnetic states and Fe-Fe distances were followed by Positron annihilation lifetime spectroscopy and Moessbauer spectroscopy, respectively, to analyze those micro-structural changes, thermally induced, which are of paramount interest to understand their brittleness problem. (Author)

Perbedaan Penggunaan Bahan Desensitizing dan Tanpa Desensitizing Pasca Bleaching Ekstra-Koronal terhadap Kekerasan Email

Directory of Open Access Journals (Sweden)

Wignyo Hadriyanto

2012-12-01

Full Text Available Latar Belakang. Pada bleaching ekstrakoronal diketahui terjadi proses demineralisasi sehingga terjadi hiersensitivitas dentin. UltraEZ salah satu bahan desensitizing yang dapat mengurangi hipersensitivitas akibat demineralisasi email pasca bleaching ekstrakoronal terkini. Tujuan penelitian ini bertujuan untuk mengetahui perbedaan kekerasan email pasca pemutihan gigi ekstra-koronal dengan aplikasi bahan desensitizing dan tanpa aplikasi bahan desensitizing. Metode penelitian ini menggunakan 20 gigi premolar permanen pasca pencabutanyang masih utuh dan direndam dalam saliva buatan, kemudian dilakukan pemolesan pada bagian bukal dengan menggunakan pasta profilaksis kemudian gigi dicuci dan dikeringkan. Bahan pemutih Opalescence Xtra Boost diaplikasikan pada semua permukaan bukal gigi premolar kemudian dibagi menjadi 2 kelompok yaitu kelompok I, II, masing-masing kelompok sebanyak 10 gigi. Kelompok I sebagai kelompok control setelah dilakukan pemutihan, tidak dilakukan aplikasi Ultra-EZ, dimasukkan dalam wadah botol dan direndam dalam saliva buatan kemudian disimpan dalam incubator. Mahkota dan akar gigi,kemudian ditanam dalam resin akrilik sesuai kelompok sebelumnya dengan permukaan bukal menghadap ke atas. Semua sampel diuji kekerasannya dengan uji kekerasan Vickers menggunakan beban 100 g selama 15 detik. Permukaan bukal menghadap ke atas, kemudian dijepit dengan alat penjepit pada meja alat Micro Vickers Hardness Tester. Sampel diatur sedemikian rupa sehingga akan terlihat gambar yang dapat diukur panjang diagonalnya langsung dengan micrometer yang ada pada lensa okuler. Nilai kekerasan email dalam Vickers hardness number (VHN juga dapat diperoleh dari table setelah mengetahui rata-rata panjang diagonal, berat badan yang digunakan dan waktu yang digunakan untuk uji kekerasan. Pengujian ini dilakukan pada setiap kelompok. Selanjutnya diuji dengan uji-t. hasil penelitian menunjukkan ada perbedaan yang bermakna antara aplikasi ultraEZ lima menit

Standard test methods for rockwell hardness of metallic materials

CERN Document Server

American Society for Testing and Materials. Philadelphia

2008-01-01

1.1 These test methods cover the determination of the Rockwell hardness and the Rockwell superficial hardness of metallic materials by the Rockwell indentation hardness principle. This standard provides the requirements for Rockwell hardness machines and the procedures for performing Rockwell hardness tests. 1.2 This standard includes additional requirements in annexes: Verification of Rockwell Hardness Testing Machines Annex A1 Rockwell Hardness Standardizing Machines Annex A2 Standardization of Rockwell Indenters Annex A3 Standardization of Rockwell Hardness Test Blocks Annex A4 Guidelines for Determining the Minimum Thickness of a Test Piece Annex A5 Hardness Value Corrections When Testing on Convex Cylindrical Surfaces Annex A6 1.3 This standard includes nonmandatory information in appendixes which relates to the Rockwell hardness test. List of ASTM Standards Giving Hardness Values Corresponding to Tensile Strength Appendix X1 Examples of Procedures for Determining Rockwell Hardness Uncertainty Appendix X...

Standard test methods for rockwell hardness of metallic materials

CERN Document Server

American Society for Testing and Materials. Philadelphia

2011-01-01

1.1 These test methods cover the determination of the Rockwell hardness and the Rockwell superficial hardness of metallic materials by the Rockwell indentation hardness principle. This standard provides the requirements for Rockwell hardness machines and the procedures for performing Rockwell hardness tests. 1.2 This standard includes additional requirements in annexes: Verification of Rockwell Hardness Testing Machines Annex A1 Rockwell Hardness Standardizing Machines Annex A2 Standardization of Rockwell Indenters Annex A3 Standardization of Rockwell Hardness Test Blocks Annex A4 Guidelines for Determining the Minimum Thickness of a Test Piece Annex A5 Hardness Value Corrections When Testing on Convex Cylindrical Surfaces Annex A6 1.3 This standard includes nonmandatory information in appendixes which relates to the Rockwell hardness test. List of ASTM Standards Giving Hardness Values Corresponding to Tensile Strength Appendix X1 Examples of Procedures for Determining Rockwell Hardness Uncertainty Appendix X...

Influence of strain hardening and thickness changes occurring in press forming process; Seikeiji no kako koka/itaatsu henka no buzai akkai tokusei ni oyobosu eikyo bunseki

Energy Technology Data Exchange (ETDEWEB)

Ueno, M; Hirota, K [Mazda Motor Corp., Hiroshima (Japan); Nakazawa, Y [Sumitomo Metal Industries Ltd., Osaka (Japan)

1997-10-01

Most components of the body structure are produced by press forming. This process make a uniform metal sheet into a component that have various material characteristics and thickness. This paper describes the estimation method of material characteristics and thickness changes based on the measured Vickers hardness, and the influence of these changes on the crush performance by using FE analysis. 4 refs., 12 figs., 2 tabs.

Characterization of TiO2–MnO2 composite electrodes synthesized using spark plasma sintering technique

CSIR Research Space (South Africa)

Tshephe, TS

2015-03-01

Full Text Available and electrochemical stability of the resulting materials were investigated. Relative densities of 99.33% and 98.49% were obtained for 90TiO2–10MnO2 and 80TiO2–10MnO2 when ball was incorporated. The 90TiO2–10MnO2 powder mixed with balls had its Vickers hardness value...

Physico-mechanical characteristics of commercially available bulk-fill composites.

Science.gov (United States)

Leprince, Julian G; Palin, William M; Vanacker, Julie; Sabbagh, Joseph; Devaux, Jacques; Leloup, Gaetane

2014-08-01

Bulk-fill composites have emerged, arguably, as a new "class" of resin-based composites, which are claimed to enable restoration in thick layers, up to 4mm. The objective of this work was to compare, under optimal curing conditions, the physico-mechanical properties of most currently available bulk-fill composites to those of two conventional composite materials chosen as references, one highly filled and one flowable "nano-hybrid" composite. Tetric EvoCeram Bulk Fill (Ivoclar-Vivadent), Venus Bulk Fill (Heraeus-Kulzer), SDR (Dentsply), X-tra Fil (VOCO), X-tra Base (VOCO), Sonic Fill (Kerr), Filtek Bulk Fill (3M-Espe), Xenius (GC) were compared to the two reference materials. The materials were light-cured for 40s in a 2mm×2mm×25mm Teflon mould. Degree of conversion was measured by Raman spectroscopy, Elastic modulus and flexural strength were evaluated by three point bending, surface hardness using Vickers microindentation before and after 24h ethanol storage, and filler weight content by thermogravimetric analysis. The ratio of surface hardness before and after ethanol storage was considered as an evaluation of polymer softening. Data were analyzed by one-way ANOVA and post hoc Tukey's test (p=0.05). The mechanical properties of the bulk-fill composites were mostly lower compared with the conventional high viscosity material, and, at best, comparable to the conventional flowable composite. Linear correlations of the mechanical properties investigated were poor with degree of conversion (0.090.8). Softening in ethanol revealed differences in polymer network density between material types. The reduction of time and improvement of convenience associated with bulk-fill materials is a clear advantage of this particular material class. However, a compromise with mechanical properties compared with more conventional commercially-available nano-hybrid materials was demonstrated by the present work. Given the lower mechanical properties of most bulk-fill materials

Thermal spray coatings replace hard chrome

International Nuclear Information System (INIS)

Schroeder, M.; Unger, R.

1997-01-01

Hard chrome plating provides good wear and erosion resistance, as well as good corrosion protection and fine surface finishes. Until a few years ago, it could also be applied at a reasonable cost. However, because of the many environmental and financial sanctions that have been imposed on the process over the past several years, cost has been on a consistent upward trend, and is projected to continue to escalate. Therefore, it is very important to find a coating or a process that offers the same characteristics as hard chrome plating, but without the consequent risks. This article lists the benefits and limitations of hard chrome plating, and describes the performance of two thermal spray coatings (tungsten carbide and chromium carbide) that compared favorably with hard chrome plating in a series of tests. It also lists three criteria to determine whether plasma spray or hard chrome plating should be selected

Structure, production and properties of high-melting compounds and systems (hard materials and hard metals)

International Nuclear Information System (INIS)

Holleck, H.; Thuemmler, F.

1979-07-01

The report contains contributions by various authors to the research project on the production, structure, and physical properties of high-melting compounds and systems (hard metals and hard materials), in particular WC-, TaC-, and MoC-base materials. (GSCH) [de

Characterization of Transition Metal Carbide Layers Synthesized by Thermo-reactive Diffusion Processes

DEFF Research Database (Denmark)

Laursen, Mads Brink; Fernandes, Frederico Augusto Pires; Christiansen, Thomas Lundin

2015-01-01

. In this study halide-activated pack cementation techniques were used on tool steel Vanadis 6 and martensitic stainless steel AISI 420 in order to produce hard layers of titanium carbide (TiC), vanadium carbide (V8C7) and chromium carbides (Cr23C6 and Cr7C3). Surface layers were characterized by scanning......Hard wear resistant surface layers of transition metal carbides can be produced by thermo-reactive diffusion processes where interstitial elements from a steel substrate together with external sources of transition metals (Ti, V, Cr etc.) form hard carbide and/or nitride layers at the steel surface...... electron microscopy, X-ray diffraction and Vickers hardness testing. The study shows that porosityfree, homogenous and very hard surface layers can be produced by thermo-reactive diffusion processes. The carbon availability of the substrate influences thickness of obtained layers, as Vanadis 6 tool steel...

Spatial distribution of the human enamel fracture toughness with aging.

Science.gov (United States)

Zheng, Qinghua; Xu, Haiping; Song, Fan; Zhang, Lan; Zhou, Xuedong; Shao, Yingfeng; Huang, Dingming

2013-10-01

A better understanding of the fracture toughness (KIC) of human enamel and the changes induced by aging is important for the clinical treatment of teeth cracks and fractures. We conducted microindentation tests and chemical content measurements on molar teeth from "young" (18 ≤ age ≤ 25) and "old" (55 ≤ age) patients. The KIC and the mineral contents (calcium and phosphorus) in the outer, the middle, and the inner enamel layers within the cuspal and the intercuspal regions of the crown were measured through the Vickers toughness test and Energy Dispersive X-Ray Spectroscopy (EDS), respectively. The elastic modulus used for the KIC calculation was measured through atomic force microscope (AFM)-based nanoindentation tests. In the outer enamel layer, two direction-specific values of the KIC were calculated separately (direction I, crack running parallel to the occlusal surface; direction II, perpendicular to direction I). The mean KIC of the outer enamel layer was lower than that of the internal layers (penamel layer, old enamel has a lower KIC, II and higher mineral contents than young enamel (penamel surface becomes more prone to cracks with aging partly due to the reduction in the interprismatic organic matrix observed with the maturation of enamel. Copyright © 2013 Elsevier Ltd. All rights reserved.

Nanoindentation studies of ex situ AlN/Al metal matrix nanocomposites

International Nuclear Information System (INIS)

Fale, Sandeep; Likhite, Ajay; Bhatt, Jatin

2014-01-01

Highlights: • Formation of in-situ phases nucleated on AlN particles strengthens the matrix. • Formation of in-situ phases increases with AlN content in nanocomposites. • Stronger in-situ phases results in increased hardness and modulus of elasticity. - Abstract: Nanocrystalline Aluminium nitride (AlN) powder is dispersed in different weight ratio in Aluminum matrix to fabricate metal matrix nanocomposite (MMNC) using ex situ melt metallurgy process. The synthesized Al–AlN nanocomposites are studied for phase analysis using high resolution scanning electron microscopy (FEG-SEM) and for hardness behavior using microindentation and nanoindentation tests. Quantitative analysis of the oxide phases is calculated from thermodynamic data and mass balance equation using elemental data obtained from energy dispersive spectroscopy (EDS) results. Role of oxide phases in association with AlN particles is investigated to understand the mechanical behavior of composites using nanoindentation tester. Load–displacement profile obtained from nanoindentation test reveals distribution of oxide phases along with AlN particle and their effect on indent penetration

Hard-hard coupling assisted anomalous magnetoresistance effect in amine-ended single-molecule magnetic junction

Science.gov (United States)

Tang, Y.-H.; Lin, C.-J.; Chiang, K.-R.

2017-06-01

We proposed a single-molecule magnetic junction (SMMJ), composed of a dissociated amine-ended benzene sandwiched between two Co tip-like nanowires. To better simulate the break junction technique for real SMMJs, the first-principles calculation associated with the hard-hard coupling between a amine-linker and Co tip-atom is carried out for SMMJs with mechanical strain and under an external bias. We predict an anomalous magnetoresistance (MR) effect, including strain-induced sign reversal and bias-induced enhancement of the MR value, which is in sharp contrast to the normal MR effect in conventional magnetic tunnel junctions. The underlying mechanism is the interplay between four spin-polarized currents in parallel and anti-parallel magnetic configurations, originated from the pronounced spin-up transmission feature in the parallel case and spiky transmission peaks in other three spin-polarized channels. These intriguing findings may open a new arena in which magnetotransport and hard-hard coupling are closely coupled in SMMJs and can be dually controlled either via mechanical strain or by an external bias.

Melting of polydisperse hard disks

NARCIS (Netherlands)

Pronk, S.; Frenkel, D.

2004-01-01

The melting of a polydisperse hard-disk system is investigated by Monte Carlo simulations in the semigrand canonical ensemble. This is done in the context of possible continuous melting by a dislocation-unbinding mechanism, as an extension of the two-dimensional hard-disk melting problem. We find

Microstructure and mechanical properties of carbon nanotubes reinforced aluminum matrix composites synthesized via equal-channel angular pressing

Energy Technology Data Exchange (ETDEWEB)

Zare, Hassan [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Jahedi, Mohammad, E-mail: mohammad.jahedi@unh.edu [Department of Mechanical Engineering, University of New Hampshire, Durham, NH 03824 (United States); Toroghinejad, Mohammad Reza; Meratian, Mahmoud [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Knezevic, Marko [Department of Mechanical Engineering, University of New Hampshire, Durham, NH 03824 (United States)

2016-07-18

In this work, 2 vol% carbon nanotubes (CNTs) reinforced aluminum (Al) matrix composites of superior microstructural homogeneity are successfully synthesized using Bc equal-channel angular extrusion (ECAP) route. The key step in arriving at high level of homogeneous distribution of CNTs within Al was preparation of the powder using simultaneous attrition milling and ultra-sonication processes. Microstructure as revealed by electron microscopy and absence of Vickers hardness gradients across the material demonstrate that the material reached the homogeneous state in terms of CNT distribution, porosity distribution, and grain structure after eight ECAP passes. To facilitate comparison of microstructure and hardness, samples of Al were processed under the same ECAP conditions. Significantly, the composite containing only 2 vol% exhibits 20% increase in hardness relative to the Al samples.

Prediction of novel hard phases of Si{sub 3}N{sub 4}: First-principles calculations

Energy Technology Data Exchange (ETDEWEB)

Cui, Lin; Hu, Meng; Wang, Qianqian; Xu, Bo; Yu, Dongli; Liu, Zhongyuan; He, Julong, E-mail: hjl@ysu.edu.cn

2015-08-15

Exploration of novel hard metastable phases of silicon nitride was performed using a recently developed particle-swarm optimization method within the CALYPSO software package. Three potential hard metastable phases of t-Si{sub 3}N{sub 4}, m-Si{sub 3}N{sub 4}, and o-Si{sub 3}N{sub 4} were predicted. These phases are mechanically and dynamically stable at ambient pressure based on their elastic constants and phonon dispersions. t-Si{sub 3}N{sub 4} and m-Si{sub 3}N{sub 4} exhibit lower energies than γ-Si{sub 3}N{sub 4} at pressures below 2.5 GPa and 2.9 GPa, respectively, which promise that the formers could be obtained by quenching from γ-Si{sub 3}N{sub 4}. o-Si{sub 3}N{sub 4} is a better high-pressure metastable phase than CaTi{sub 2}O{sub 4}-type Si{sub 3}N{sub 4} proposed by Tatsumi et al. and it can come from the transition of γ-Si{sub 3}N{sub 4} under 198 GPa. The theoretical band gaps of t-Si{sub 3}N{sub 4}, m-Si{sub 3}N{sub 4}, and o-Si{sub 3}N{sub 4} at ambient pressure were 3.15 eV, 3.90 eV, and 3.36 eV, respectively. At ambient pressure, the Vickers hardness values of t-Si{sub 3}N{sub 4} (32.6 GPa), m-Si{sub 3}N{sub 4} (31.5 GPa), and o-Si{sub 3}N{sub 4} (36.1 GPa) are comparable to β-Si{sub 3}N{sub 4} and γ-Si{sub 3}N{sub 4}. With the pressure increasing, t-Si{sub 3}N{sub 4}, m-Si{sub 3}N{sub 4}, and o-Si{sub 3}N{sub 4} will change from the brittle to ductile state at about 15.7 GPa, 7.3 GPa and 28.9 GPa, respectively. - Graphical abstract: This figure shows the crystal structures of three Si{sub 3}N{sub 4} predicted in this manuscript, and left to right: t-Si{sub 3}N{sub 4}, m-Si{sub 3}N{sub 4} and o-Si{sub 3}N{sub 4}. - Highlights: • We explored three metastable phases of Si{sub 3}N{sub 4} — t-Si{sub 3}N{sub 4}, m-Si{sub 3}N{sub 4}, and o-Si{sub 3}N{sub 4}. • The enthalpies of t and m- are much lower than that of γ at ambient pressure. • ois one further high pressure phase than γ. • o-Si{sub 3}N{sub 4} is the most hardest phase in Si

Advances in hard nucleus cataract surgery

Directory of Open Access Journals (Sweden)

Wei Cui

2013-11-01

Full Text Available Security and perfect vision and fewer complications are our goals in cataract surgery, and hard-nucleus cataract surgery is always a difficulty one. Many new studies indicate that micro-incision phacoemulsification in treating hard nucleus cataract is obviously effective. This article reviews the evolution process of hard nuclear cataract surgery, the new progress in the research of artificial intraocular lens for microincision, and analyse advantages and disadvantages of various surgical methods.

Hardening and softening analysis of pure titanium based on the dislocation density during torsion deformation

Energy Technology Data Exchange (ETDEWEB)

Chen, Han; Li, Fuguo, E-mail: fuguolx@nwpu.edu.cn; Li, Jinghui; Ma, Xinkai; Li, Jiang; Wan, Qiong

2016-08-01

The hardening and softening phenomena during torsion deformation are studied based on the Taylor dislocation model for pure titanium. The hardening and softening phenomena are observed through the hardness analysis during micro-indentation test and micro-hardness test. Besides, the variations of indentation size also verify the existence of hardening and softening phenomena during torsion. The variations of geometric necessary dislocations (GNDs) and statistic store dislocations (SSDs) state that the positions of high dislocation density and low dislocation density correspond to the positions of hardening and softening. The results from the microstructure, grain boundaries evolution and twins analysis indicate the twins play an important role in appearance of hardening and softening phenomena. The appearance of hardening and softening phenomena are attributed to the combination of different slip systems and twinning systems combining with the Schmid Factor (SF) analysis and the transmission electron microscope (TEM). The appearance of hardening and softening phenomena can be explained by the Taylor dislocation theory based on TEM analysis. - Highlights: • The phenomena can be characterized by Taylor dislocation model. • The variation of GNDs leads to the phenomena. • The phenomena are proved by micro-hardness, indentation hardness. • The {10-12} twin and {11-24} twin play an important role in the phenomena.

Analysis, manufacture and characterization of Ni/Cu functionally graded structures

International Nuclear Information System (INIS)

Rubio, Wilfredo Montealegre; Paulino, Glaucio H.; Silva, Emilio Carlos Nelli

2012-01-01

Highlights: ► Functionally graded structures (FGSs) of nickel and copper can be manufactured. ► The hardness curve of FGS can be used for approximating the gradation function of elastic properties. ► The graded finite element approaches with great accuracy the FGS resonance frequencies obtained experimentally. -- Abstract: In this work, an experimental and numerical analysis and characterization of functionally graded structures (FGSs) is developed. Nickel (Ni) and copper (Cu) materials are used as basic materials in the numerical modeling and experimental characterization. For modeling, a MATLAB finite element code is developed, which allows simulation of harmonic and modal analysis considering the graded finite element formulation. For experimental characterization, Ni–Cu FGSs are manufactured by using spark plasma sintering technique. Hardness and Young’s modulus are found by using microindentation and ultrasonic measurements, respectively. The effective gradation of Ni/Cu FGS is addressed by means of optical microscopy, energy dispersive spectrometry, scanning electron microscopy and hardness testing. For the purpose of comparing modeling and experimental results, the hardness curve, along the gradation direction, is used for identifying the gradation profile; accordingly, the experimental hardness curve is used for approximating the Young’s modulus variation and the graded finite element modeling is used for verification. For the first two resonance frequency values, a difference smaller than 1% between simulated and experimental results is obtained.

Enamel microhardness and bond strengths of self-etching primer adhesives.

Science.gov (United States)

Adebayo, Olabisi A; Burrow, Michael F; Tyas, Martin J; Adams, Geoffrey G; Collins, Marnie L

2010-04-01

The aim of this study was to determine the relationship between enamel surface microhardness and microshear bond strength (microSBS). Buccal and lingual mid-coronal enamel sections were prepared from 22 permanent human molars and divided into two groups, each comprising the buccal and lingual enamel from 11 teeth, to analyze two self-etching primer adhesives (Clearfil SE Bond and Tokuyama Bond Force). One-half of each enamel surface was tested using the Vickers hardness test with 10 indentations at 1 N and a 15-s dwell time. A hybrid resin composite was bonded to the other half of the enamel surface with the adhesive system assigned to the group. After 24 h of water storage of specimens at 37 degrees C, the microSBS test was carried out on a universal testing machine at a crosshead speed of 1 mm min(-1) until bond failure occurred. The mean microSBS was regressed on the mean Vickers hardness number (VHN) using a weighted regression analysis in order to explore the relationship between enamel hardness and microSBS. The weights used were the inverse of the variance of the microSBS means. Neither separate correlation analyses for each adhesive nor combined regression analyses showed a significant correlation between the VHN and the microSBS. These results suggest that the microSBS of the self-etch adhesive systems are not influenced by enamel surface microhardness.

Damage sensing ability of polymer nanocomposites filled with long, shortened and damaged carbon nanotubes

OpenAIRE

Inam, Fawad; Okolo, Chichi; Vo, Thuc

2016-01-01

Carbon nanotubes (CNTs) were aggressively tip-ultrasonicated to produce shortened and damaged carbon nanotubes. High-resolution scanning electron microscopic analysis was performed to measure the dimensions of CNTs. Thermo-gravimetric analysis (TGA) was used to evaluate the damage in the sonicated CNTs. Shortened CNTs, in their pristine form (undamaged), were used for comparison with damaged CNTs. Nanocomposite bars, containing CNTs, were indented using Vickers hardness testing machine to pro...

Initiative hard coal; Initiative Steinkohle

Energy Technology Data Exchange (ETDEWEB)

Leonhardt, J.

2007-08-02

In order to decrease the import dependence of hard coal in the European Union, the author has submitted suggestions to the director of conventional sources of energy (directorate general for energy and transport) of the European community, which found a positive resonance. These suggestions are summarized in an elaboration 'Initiative Hard Coal'. After clarifying the starting situation and defining the target the presupposition for a better use of hard coal deposits as raw material in the European Union are pointed out. On that basis concrete suggestions for measures are made. Apart from the conditions of the deposits it concerns thereby also new mining techniques and mining-economical developments, connected with tasks for the mining-machine industry. (orig.)

Hard diffraction and rapidity gaps

International Nuclear Information System (INIS)

Brandt, A.

1995-09-01

The field of hard diffraction, which studies events with a rapidity gap and a hard scattering, has expanded dramatically recently. A review of new results from CDF, D OE, H1 and ZEUS will be given. These results include diffractive jet production, deep-inelastic scattering in large rapidity gap events, rapidity gaps between high transverse energy jets, and a search for diffractive W-boson production. The combination of these results gives new insight into the exchanged object, believed to be the pomeron. The results axe consistent with factorization and with a hard pomeron that contains both quarks and gluons. There is also evidence for the exchange of a strongly interacting color singlet in high momentum transfer (36 2 ) events

Genetic analysis of kernel texture (grain hardness) in a hard red spring wheat (Triticum aestivum L.) bi-parental population

Science.gov (United States)

Grain hardness is a very important trait in determining wheat market class and also influences milling and baking traits. At the grain Hardness (Ha) locus on chromosome 5DS, there are two primary mutations responsible for conveying a harder kernel texture among U.S. hard red spring wheats: (1) the P...

Improving the tribocorrosion resistance of Ti6Al4V surface by laser surface cladding with TiNiZrO2 composite coating

Science.gov (United States)

Obadele, Babatunde Abiodun; Andrews, Anthony; Mathew, Mathew T.; Olubambi, Peter Apata; Pityana, Sisa

2015-08-01

Ti6Al4V alloy was laser cladded with titanium, nickel and zirconia powders in different ratio using a 2 kW CW ytterbium laser system (YLS). The microstructures of the cladded layers were examined using field emission scanning electron microscopy (FESEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffractometry (XRD). Corrosion and tribocorrosion tests were performed on the cladded surface in 1 M H2SO4 solution. The microstructure revealed the transformation from a dense dendritic structure in TiNi coating to a flower-like structure observed in TiNiZrO2 cladded layers. There was a significant increase in surface microindentation hardness values of the cladded layers due to the present of hard phase ZrO2 particles. The results obtained show that addition of ZrO2 improves the corrosion resistance property of TiNi coating but decrease the tribocorrosion resistance property. The surface hardening effect induced by ZrO2 addition, combination of high hardness of Ti2Ni phase could be responsible for the mechanical degradation and chemical wear under sliding conditions.

Impact of aging on radiation hardness

International Nuclear Information System (INIS)

Shaneyfelt, M.R.; Winokur, P.S.; Fleetwood, D.M.

1997-01-01

Burn-in effects are used to demonstrate the potential impact of thermally activated aging effects on functional and parametric radiation hardness. These results have implications on hardness assurance testing. Techniques for characterizing aging effects are proposed

Application of instrumented microhardness method to follow the thermal ageing of cast duplex stainless steel

International Nuclear Information System (INIS)

Rezakhanlou, R.; Massoud, J.P.

1993-03-01

During the thermal ageing of cast duplex stainless steel the ferrite hardness largely increases. The measurement of the ferrite phase hardness can give us an indication of the level of the ageing process. But in order to have a representative value of the ferrite hardness, the applied load must be low enough. For this reason, we have used the instrumented microhardness (IMH) test which consists to measure continuously the applied load and the indentation depth during the operation. The mechanical analysis of the so called indentation curve allows us to calculate the hardness and the young modulus of the indented material for loads as low as 2 g. The results confirm the Vickers microhardness measurement under 50 g loads i.e. a sharp increase of the ferrite hardness (x 2.3 as compared to the as received state) for the highly aged sample. It should be noted that the results obtained with the IMH are completely independent of the operator. (authors). 18 refs., 7 figs., 6 tabs

Isotropic-nematic transition in a mixture of hard spheres and hard spherocylinders: scaled particle theory description

Directory of Open Access Journals (Sweden)

M.F. Holovko

2017-12-01

Full Text Available The scaled particle theory is developed for the description of thermodynamical properties of a mixture of hard spheres and hard spherocylinders. Analytical expressions for free energy, pressure and chemical potentials are derived. From the minimization of free energy, a nonlinear integral equation for the orientational singlet distribution function is formulated. An isotropic-nematic phase transition in this mixture is investigated from the bifurcation analysis of this equation. It is shown that with an increase of concentration of hard spheres, the total packing fraction of a mixture on phase boundaries slightly increases. The obtained results are compared with computer simulations data.

Effect of Sn addition on phases stability and mechanical properties of aged Ti-10Mo Alloy; Efeito da adicao de Sn na estabilidade de fases e propriedades de ligas Ti-10Mo resfriadas rapidamente e envelhecidas

Energy Technology Data Exchange (ETDEWEB)

Cardoso, F.F.; Lopes, E.S.N.; Cremasco, A.; Contieri, R.J.; Mello, M.G.; Caram, R., E-mail: flaviamec@fem.unicamp.b [Universidade Estadual de Campinas (FEM/UNICAMP), SP (Brazil). Fac. de Engenharia Mecanica

2010-07-01

Nowadays there is considerable effort in order to develop new titanium alloys using non-toxic elements such as Mo and Sn. This work deals with the alloys Ti-Mo-Sn. The samples were melted, homogenized and hot swaged. Afterwards they were solubilized and water quenched. The alloys were also aged at several temperatures Characterization involved determination of Young's modulus, hardness, X-ray diffraction and optical microscopy. The X-ray diffraction indicated the presence of athermal and isothermal {omega} phase for Ti-10Mo alloy. One also evidenced that the Vickers hardness varies with the temperature and the time of aging heat treatment. (author)

Hard and soft acids and bases: atoms and atomic ions.

Science.gov (United States)

Reed, James L

2008-07-07

The structural origin of hard-soft behavior in atomic acids and bases has been explored using a simple orbital model. The Pearson principle of hard and soft acids and bases has been taken to be the defining statement about hard-soft behavior and as a definition of chemical hardness. There are a number of conditions that are imposed on any candidate structure and associated property by the Pearson principle, which have been exploited. The Pearson principle itself has been used to generate a thermodynamically based scale of relative hardness and softness for acids and bases (operational chemical hardness), and a modified Slater model has been used to discern the electronic origin of hard-soft behavior. Whereas chemical hardness is a chemical property of an acid or base and the operational chemical hardness is an experimental measure of it, the absolute hardness is a physical property of an atom or molecule. A critical examination of chemical hardness, which has been based on a more rigorous application of the Pearson principle and the availability of quantitative measures of chemical hardness, suggests that the origin of hard-soft behavior for both acids and bases resides in the relaxation of the electrons not undergoing transfer during the acid-base interaction. Furthermore, the results suggest that the absolute hardness should not be taken as synonymous with chemical hardness but that the relationship is somewhat more complex. Finally, this work provides additional groundwork for a better understanding of chemical hardness that will inform the understanding of hardness in molecules.

Hard Copy Market Overview

Science.gov (United States)

Testan, Peter R.

1987-04-01

A number of Color Hard Copy (CHC) market drivers are currently indicating strong growth in the use of CHC technologies for the business graphics marketplace. These market drivers relate to product, software, color monitors and color copiers. The use of color in business graphics allows more information to be relayed than is normally the case in a monochrome format. The communicative powers of full-color computer generated output in the business graphics application area will continue to induce end users to desire and require color in their future applications. A number of color hard copy technologies will be utilized in the presentation graphics arena. Thermal transfer, ink jet, photographic and electrophotographic technologies are all expected to be utilized in the business graphics presentation application area in the future. Since the end of 1984, the availability of color application software packages has grown significantly. Sales revenue generated by business graphics software is expected to grow at a compound annual growth rate of just over 40 percent to 1990. Increased availability of packages to allow the integration of text and graphics is expected. Currently, the latest versions of page description languages such as Postscript, Interpress and DDL all support color output. The use of color monitors will also drive the demand for color hard copy in the business graphics market place. The availability of higher resolution screens is allowing color monitors to be easily used for both text and graphics applications in the office environment. During 1987, the sales of color monitors are expected to surpass the sales of monochrome monitors. Another major color hard copy market driver will be the color copier. In order to take advantage of the communications power of computer generated color output, multiple copies are required for distribution. Product introductions of a new generation of color copiers is now underway with additional introductions expected

Development of method for evaluating cell hardness and correlation between bacterial spore hardness and durability

Directory of Open Access Journals (Sweden)

Nakanishi Koichi

2012-06-01

Full Text Available Abstract Background Despite the availability of conventional devices for making single-cell manipulations, determining the hardness of a single cell remains difficult. Here, we consider the cell to be a linear elastic body and apply Young’s modulus (modulus of elasticity, which is defined as the ratio of the repulsive force (stress in response to the applied strain. In this new method, a scanning probe microscope (SPM is operated with a cantilever in the “contact-and-push” mode, and the cantilever is applied to the cell surface over a set distance (applied strain. Results We determined the hardness of the following bacterial cells: Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and five Bacillus spp. In log phase, these strains had a similar Young’s modulus, but Bacillus spp. spores were significantly harder than the corresponding vegetative cells. There was a positive, linear correlation between the hardness of bacterial spores and heat or ultraviolet (UV resistance. Conclusions Using this technique, the hardness of a single vegetative bacterial cell or spore could be determined based on Young’s modulus. As an application of this technique, we demonstrated that the hardness of individual bacterial spores was directly proportional to heat and UV resistance, which are the conventional measures of physical durability. This technique allows the rapid and direct determination of spore durability and provides a valuable and innovative method for the evaluation of physical properties in the field of microbiology.

Hard coatings

International Nuclear Information System (INIS)

Dan, J.P.; Boving, H.J.; Hintermann, H.E.

1993-01-01

Hard, wear resistant and low friction coatings are presently produced on a world-wide basis, by different processes such as electrochemical or electroless methods, spray technologies, thermochemical, CVD and PVD. Some of the most advanced processes, especially those dedicated to thin film depositions, basically belong to CVD or PVD technologies, and will be looked at in more detail. The hard coatings mainly consist of oxides, nitrides, carbides, borides or carbon. Over the years, many processes have been developed which are variations and/or combinations of the basic CVD and PVD methods. The main difference between these two families of deposition techniques is that the CVD is an elevated temperature process (≥ 700 C), while the PVD on the contrary, is rather a low temperature process (≤ 500 C); this of course influences the choice of substrates and properties of the coating/substrate systems. Fundamental aspects of the vapor phase deposition techniques and some of their influences on coating properties will be discussed, as well as the very important interactions between deposit and substrate: diffusions, internal stress, etc. Advantages and limitations of CVD and PVD respectively will briefly be reviewed and examples of applications of the layers will be given. Parallel to the development and permanent updating of surface modification technologies, an effort was made to create novel characterisation methods. A close look will be given to the coating adherence control by means of the scratch test, at the coating hardness measurement by means of nanoindentation, at the coating wear resistance by means of a pin-on-disc tribometer, and at the surface quality evaluation by Atomic Force Microscopy (AFM). Finally, main important trends will be highlighted. (orig.)

Hard and soft acids and bases: structure and process.

Science.gov (United States)

Reed, James L

2012-07-05

Under investigation is the structure and process that gives rise to hard-soft behavior in simple anionic atomic bases. That for simple atomic bases the chemical hardness is expected to be the only extrinsic component of acid-base strength, has been substantiated in the current study. A thermochemically based operational scale of chemical hardness was used to identify the structure within anionic atomic bases that is responsible for chemical hardness. The base's responding electrons have been identified as the structure, and the relaxation that occurs during charge transfer has been identified as the process giving rise to hard-soft behavior. This is in contrast the commonly accepted explanations that attribute hard-soft behavior to varying degrees of electrostatic and covalent contributions to the acid-base interaction. The ability of the atomic ion's responding electrons to cause hard-soft behavior has been assessed by examining the correlation of the estimated relaxation energies of the responding electrons with the operational chemical hardness. It has been demonstrated that the responding electrons are able to give rise to hard-soft behavior in simple anionic bases.

Effects of applying anchovy (Stolephorus insularis) substrates on the microhardness of tooth enamel in Sprague-Dawley rats

Science.gov (United States)

Hendrik, Y. C.; Puspitawati, R.; Gunawan, H. A.

2017-08-01

Anchovies (Stolephorus insularis) contain high levels of fluor in the form of CaF2. The aim of this study is to analyze changes in tooth enamel microhardness after application of anchovy substrates by feeding or as a topical fluoridation material. An in vivo study of the lower left incisors of nine Sprague-Dawley rats was conducted. The sample was comprised of baseline and treatment groups, including feeding application, topical application, negative control feeding, and negative control topical groups. The treatment groups were given 5% anchovy substrates through feeding and topical applications. After treatment, tooth samples were extracted from each of the rats for examination, and statistical analyses were performed after determining hardness numbers for enamel surfaces using Vickers microhardness tester. Vickers hardness numbers (VHNs) for anchovy substrate application and consumption by feeding (440.3 ± 24.72) were higher than for the negative control (315.80 ± 17.51). VHNs for the topical application group were higher than for the negative control (347.28 ± 28.56) and for the feeding group. The use of anchovy as a fluoridation material in form of topical application is potentially an effective method for increasing the microhardness of the tooth enamel surface

The In vitro Evaluation of the effect of xyliwhite, probiotic, and the conventional toothpastes on the enamel roughness and microhardness.

Science.gov (United States)

Maden, E Arat; Altun, C; Polat, G Guven; Basak, F

2018-03-01

The aim of this study was to evaluate the effect of fluoride, Xylitol, Probiotic, and Whitening toothpastes on the permanent teeth enamel roughness and microhardness. One hundred and twenty teeth were randomly divided into 2 groups, each group having 60 samples. G1: The group in which enamel roughness was examined (n = 60). G2: The group in which enamel microhardness was examined (n = 60). Then, these groups were randomly divided into 4 groups among themselves (n = 15). Each group was brushed using four different toothpastes for 1 week with a battery-powered toothbrush in the morning and evening for 2 min. Vicker's hardness tester was used to measure the changes in microhardness, and the profilometer was used to measure the changes in surface roughness. No statistically significant differences were found on surface roughness and microhardness values measured after tooth brushing process in group brushed with Colgate MaxFresh toothpaste (P > 0.01). Statistically significant decrease was observed on Vicker's hardness values measured after tooth brushing process in groups brushed with Ipana White Power Carbonate toothpaste, Xyliwhite Toothpaste Gel, and Periobiotic Probiotic Toothpaste (P tooth enamel surface roughness and microhardness. Xyliwhite, Periobiotic, and Ipana White Power Carbonate-containing abrasive toothpastes led to changes negatively on permanent tooth enamel surface roughness and microhardness.

Crystal structures, stability, electronic and elastic properties of 4d and 5d transition metal monoborides: First-principles calculations

Energy Technology Data Exchange (ETDEWEB)

Wang, Y.; Chen, W. [International Center for New-Structured Materials (ICNSM), Zhejiang University, and Laboratory of New-Structured Materials, State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Chen, X.; Liu, H.Y. [State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); Ding, Z.H.; Ma, Y.M. [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, Changchun 130012 (China); Wang, X.D.; Cao, Q.P. [International Center for New-Structured Materials (ICNSM), Zhejiang University, and Laboratory of New-Structured Materials, State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Jiang, J.Z., E-mail: jiangjz@zju.edu.cn [International Center for New-Structured Materials (ICNSM), Zhejiang University, and Laboratory of New-Structured Materials, State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

2012-10-15

Highlights: Black-Right-Pointing-Pointer Changes from NaCl-, WC- to anti-NiAs-type structures are for 4d and 5d metal monoborides. Black-Right-Pointing-Pointer Vickers hardnesses of monoborides are relatively low. Black-Right-Pointing-Pointer B-vacancies cause the difference in lattice parameters for IrB and PtB. Black-Right-Pointing-Pointer Nonstoichiometric IrB and PtB phases synthesized. - Abstract: The crystal structures, stability, electronic and elastic properties of 4d and 5d transition metal monoborides have been studied by first principles calculations. It is found that NaCl-type ZrB, NbB, MoB, HfB, TaB and WB, WC-type TcB, RuB, ReB, OsB and IrB, and anti-NiAs-type RhB and PdB are thermodynamically stable at zero pressure. They all are metallic. The Vickers hardnesses of these monoborides are relatively low as compared with monocarbides and mononitrides. It is clarified that the presence of B-vacancies is the origin for the difference of lattice parameters between theoretical and experimental results for WC-type IrB and anti-NiAs-type PtB while IrB and PtB with stoichiometry from calculations are revealed to be mechanically unstable and dynamically unstable, respectively.

Crystal structures, stability, electronic and elastic properties of 4d and 5d transition metal monoborides: First-principles calculations

International Nuclear Information System (INIS)

Wang, Y.; Chen, W.; Chen, X.; Liu, H.Y.; Ding, Z.H.; Ma, Y.M.; Wang, X.D.; Cao, Q.P.; Jiang, J.Z.

2012-01-01

Highlights: ► Changes from NaCl-, WC- to anti-NiAs-type structures are for 4d and 5d metal monoborides. ► Vickers hardnesses of monoborides are relatively low. ► B-vacancies cause the difference in lattice parameters for IrB and PtB. ► Nonstoichiometric IrB and PtB phases synthesized. - Abstract: The crystal structures, stability, electronic and elastic properties of 4d and 5d transition metal monoborides have been studied by first principles calculations. It is found that NaCl-type ZrB, NbB, MoB, HfB, TaB and WB, WC-type TcB, RuB, ReB, OsB and IrB, and anti-NiAs-type RhB and PdB are thermodynamically stable at zero pressure. They all are metallic. The Vickers hardnesses of these monoborides are relatively low as compared with monocarbides and mononitrides. It is clarified that the presence of B-vacancies is the origin for the difference of lattice parameters between theoretical and experimental results for WC-type IrB and anti-NiAs-type PtB while IrB and PtB with stoichiometry from calculations are revealed to be mechanically unstable and dynamically unstable, respectively.

Correlating particle hardness with powder compaction performance.

Science.gov (United States)

Cao, Xiaoping; Morganti, Mikayla; Hancock, Bruno C; Masterson, Victoria M

2010-10-01

Assessing particle mechanical properties of pharmaceutical materials quickly and with little material can be very important to early stages of pharmaceutical research. In this study, a wide range of pharmaceutical materials were studied using atomic force microscopy (AFM) nanoindentation. A significant amount of particle hardness and elastic modulus data were provided. Moreover, powder compact mechanical properties of these materials were investigated in order to build correlation between the particle hardness and powder compaction performance. It was found that the materials with very low or high particle hardness most likely exhibit poor compaction performance while the materials with medium particle hardness usually have good compaction behavior. Additionally, the results from this study enriched Hiestand's special case concept on particle hardness and powder compaction performance. This study suggests that the use of AFM nanoindentation can help to screen mechanical properties of pharmaceutical materials at early development stages of pharmaceutical research.

Physical properties and comparative strength of a bioactive luting cement.

Science.gov (United States)

Jefferies, Steven; Lööf, Jesper; Pameijer, Cornelis H; Boston, Daniel; Galbraith, Colin; Hermansson, Leif

2013-01-01

New dental cement formulations require testing to determine physical and mechanical laboratory properties. To test an experimental calcium aluminate/glass-ionomer cement, Ceramir C and B (CC and B), regarding compressive strength (CS), film thickness (FT), net setting time (ST) and Vickers hardness. An additional test to evaluate potential dimensional change/expansion properties of this cement was also conducted. CS was measured according to a slightly modified ISO 9917:2003 for the CC and B specimens. The samples were not clamped while being exposed to relative humidity of great than 90 percent at 37 degrees C for 10 minutes before being stored in phosphate-buffered saline at 37 degrees C. For the CS, four groups were tested: Group 1-CC and B; Group 2-RelyX Luting Cement; Group 3-Fuji Plus; and Group 4-RelyX Unicem. Samples from all groups were stored for 24 hours before testing. Only CCandB was tested for ST and FT according to ISO 9917:2003. The FT was tested 2 minutes after mixing. Vickers hardness was evaluated using the CSM Microhardness Indentation Tester using zinc phosphate cement as a comparison material. Expansion testing included evaluating potential cracks in feldspathic porcelain jacket crowns (PJCs). The mean and standard deviation after 24 hours were expressed in MPa: Group 1 equals 160 plus or equal to 27; Group 2 equals 96 plus or equal to 10; Group 3 equals 138 plus or equal to 15; Group 4 equals 157 plus or equal to 10. A single-factor ANOVA demonstrated statistically significant differences between the groups (P less than 0.001). Pair-wise statistical comparison demonstrated a statistically significant difference between Groups 1 and 2. No statistically significant differences were found between other groups. The FT was 16.8 plus or equal to 0.9 and the ST was 4.8 plus or equal to 0.1 min. Vickers hardness for Ceramir C and B was 68.3 plus or equal to 17.2 and was statistically significantly higher (P less than 0.05) than Fleck's Zinc Phosphate

Methane in German hard coal mining

International Nuclear Information System (INIS)

Martens, P.N.; Den Drijver, J.

1995-01-01

Worldwide, hard coal mining is being carried out at ever increasing depth, and has, therefore, to cope with correspondingly increasing methane emissions are caused by coal mining. Beside carbon dioxide, chloro-fluoro-carbons (CFCs) and nitrogen oxides, methane is one of the most significant 'greenhouse' gases. It is mainly through the release of such trace gases that the greenhouse effect is brought about. Reducing methane emissions is therefore an important problem to be solved by the coal mining industry. This paper begins by highlighting some of the fundamental principles of methane in hard coal mining. The methane problem in German hard coal mining and the industry's efforts to reduce methane emissions are presented. The future development in German hard coal mining is illustrated by an example which shows how large methane volumes can be managed, while still maintaining high outputs at increasing depth. (author). 7 tabs., 10 figs., 20 refs

Double hard scattering without double counting

Energy Technology Data Exchange (ETDEWEB)

Diehl, Markus [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Gaunt, Jonathan R. [VU Univ. Amsterdam (Netherlands). NIKHEF Theory Group; Schoenwald, Kay [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

2017-02-15

Double parton scattering in proton-proton collisions includes kinematic regions in which two partons inside a proton originate from the perturbative splitting of a single parton. This leads to a double counting problem between single and double hard scattering. We present a solution to this problem, which allows for the definition of double parton distributions as operator matrix elements in a proton, and which can be used at higher orders in perturbation theory. We show how the evaluation of double hard scattering in this framework can provide a rough estimate for the size of the higher-order contributions to single hard scattering that are affected by double counting. In a numeric study, we identify situations in which these higher-order contributions must be explicitly calculated and included if one wants to attain an accuracy at which double hard scattering becomes relevant, and other situations where such contributions may be neglected.

Double hard scattering without double counting

International Nuclear Information System (INIS)

Diehl, Markus; Gaunt, Jonathan R.

2017-02-01

Double parton scattering in proton-proton collisions includes kinematic regions in which two partons inside a proton originate from the perturbative splitting of a single parton. This leads to a double counting problem between single and double hard scattering. We present a solution to this problem, which allows for the definition of double parton distributions as operator matrix elements in a proton, and which can be used at higher orders in perturbation theory. We show how the evaluation of double hard scattering in this framework can provide a rough estimate for the size of the higher-order contributions to single hard scattering that are affected by double counting. In a numeric study, we identify situations in which these higher-order contributions must be explicitly calculated and included if one wants to attain an accuracy at which double hard scattering becomes relevant, and other situations where such contributions may be neglected.

Effect of γ-IRRADIATION on the Mechanical Properties of Al-Cu Alloy

Science.gov (United States)

Abo-Elsoud, M.; Ismail, H.; Sobhy, Maged S.

SEM observations and Vickers hardness tests were performed to identify the irradiation effects. γ-irradiation effect during the aging hardening process can be explained depending on the composition of the alloy and is used to derive quantitative information on the kinetics of the transformation precipitates. Increasing the Cu content of an Al-Cu alloy can improve the aging hardness. The present results of the hardness behavior, with SEM observations of surveillance specimens at different doses, suggest that the radiation-induced defects are probably complex valence-solute clusters. These clusters act as nuclei for the precipitation of θ-Al2Cu type. This can be effectively utilized to study the systematics of nucleation of precipitates at vacancy-type defects. γ-irradiation probably plays the key role in defects responsible for material strengthening and embrittlement.

TiC含量对WC-TiC-TaC硬质合金材料微观组织及力学性能的影响%Effects of TiC Content on Microstructure and Mechanical Property of WC-TiC-TaC Cemented Carbides

Institute of Scientific and Technical Information of China (English)

高姣姣; 姜龙凯; 宋金鹏; 梁国星; 安晶; 谢俊彩; 曹磊; 吕明

2017-01-01

本研究采用真空热压烧结技术,在1600℃下制备了WC-TiC-TaC硬质合金材料,研究了TiC含量对其微观组织及力学性能的影响.结果表明,随着TiC含量的增多,硬质合金材料的晶粒显著增大.当TiC的含量从10wt％ 增加到25wt％时,硬质合金材料的硬度逐渐增大,最高可达19.81 GPa,这是由于TiC的硬度高于基体WC的硬度;与此同时,硬质合金材料的抗弯强度和断裂韧度逐渐减小.当TiC的含量为10wt％时,材料的抗弯强度有最大值,其值为1147.24 MPa,这是由于在材料内部形成了均匀、细小的晶粒组织;在此含量下,复合材料的增韧机理为细晶增韧、裂纹偏转、裂纹分支、裂纹桥接和韧窝增韧,其断裂韧度有最大值,为14.60 MPa·m1/2.%WC-TiC-TaC cemented carbides were fabricated by hot-pressed sintering at 1600℃. Effects of TiC content on the microstructure and mechanical properties of these cemented carbides were investigated. It was found that when TiC content was increased from 10wt％ to 25wt％, both the average grain size and the Vickers hardness increased pro-gressively, but both the flexural strength and the fracture toughness decreased gradually. The increase of Vickers hard-ness was attributed to the increase of TiC content and the hardness of TiC was higher than that of WC. The value of the highest Vickers hardness was 19.81 GPa. This work also showed that the highest flexural strength (1147.24 MPa) was ascribed to the fine and homogeneous grains, and that the highest fracture toughness (14.60 MPa·m1/2) was due to the intensive coupled mechanism of the fine-grain toughening, crack deflection, crack branching, crack bridging, and toughness dimples.

Gradient microstructure and microhardness in a nitrided 18CrNiMo7-6 gear steel

Science.gov (United States)

Yang, R.; Wu, G. L.; Zhang, X.; Fu, W. T.; Huang, X.

2017-07-01

A commercial gear steel (18CrNiMo7-6) containing a tempered martensite structure was nitrided using a pressurized gas nitriding process under a pressure of 5 atm at 530 °C for 5 hours. The mechanical properties and microstructure of the nitrided sample were characterized by Vickers hardness measurements, X-ray diffraction, and backscatter electron imaging in a scanning electron microscope. A micro-hardness gradient was identified over a distance of 500 μm with hardness values of 900 HV at the top surface and 300 HV in the core. This micro-hardness gradient corresponds to a gradient in the microstructure that changes from a nitride compound layer at the top surface (∼ 20 μm thick) to a diffusion zone with a decreasing nitrogen concentration and precipitate density with distance from the surface, finally reaching the core matrix layer with a recovered martensite structure.

Analysis of Hard Thin Film Coating

Science.gov (United States)

Shen, Dashen

1998-01-01

MSFC is interested in developing hard thin film coating for bearings. The wearing of the bearing is an important problem for space flight engine. Hard thin film coating can drastically improve the surface of the bearing and improve the wear-endurance of the bearing. However, many fundamental problems in surface physics, plasma deposition, etc, need further research. The approach is using electron cyclotron resonance chemical vapor deposition (ECRCVD) to deposit hard thin film an stainless steel bearing. The thin films in consideration include SiC, SiN and other materials. An ECRCVD deposition system is being assembled at MSFC.

Subgroup report on hard x-ray microprobes

International Nuclear Information System (INIS)

Ice, G.E.; Barbee, T.; Bionta, R.; Howells, M.; Thompson, A.C.; Yun, W.

1994-01-01

The increasing availability of synchrotron x-ray sources has stimulated the development of advanced hard x-ray (E≥5 keV) microprobes. New x-ray optics have been demonstrated which show promise for achieving intense submicron hard x-ray probes. These probes will be used for extraordinary elemental detection by x-ray fluorescence/absorption and for microdiffraction to identify phase and strain. The inherent elemental and crystallographic sensitivity of an x-ray microprobe and its inherently nondestructive and penetrating nature makes the development of an advanced hard x-ray microprobe an important national goal. In this workshop state-of-the-art hard x-ray microprobe optics were described and future directions were discussed. Gene Ice, Oak Ridge National Laboratory (ORNL), presented an overview of the current status of hard x-ray microprobe optics and described the use of crystal spectrometers to improve minimum detectable limits in fluorescent microprobe experiments. Al Thompson, Lawrence Berkeley Laboratory (LBL), described work at the Center for X-ray Optics to develop a hard x-ray microprobe based on Kirkpatrick-Baez (KB) optics. Al Thompson also showed the results of some experimental measurements with their KB optics. Malcolm Howells presented a method for bending elliptical mirrors and Troy Barbee commented on the use of graded d spacings to achieve highest efficiency in KB multilayer microfocusing. Richard Bionta, Lawrence Livermore National Laboratory (LLNL), described the development of the first hard x-ray zone plates and future promise of so called open-quotes jelly rollclose quotes or sputter slice zone plates. Wenbing Yun, Argonne National Laboratory (ANL), described characterization of jelly roll and lithographically produced zone plates and described the application of zone plates to focus extremely narrow bandwidths by nuclear resonance. This report summarizes the presentations of the workshop subgroup on hard x-ray microprobes

Analysis of the development and performance of hard disks

OpenAIRE

Novak, Davorin

2010-01-01

With the emergence of new technologies in the field of hard drives we can witness a significant increase of surface density and transfer rate of interfaces which, as a result, enables greater performance and reliability of hard disks. The reason for this are increasing needs for higher capacities and data transfer rate to or from the hard disk. This thesis presents the structure of hard drives, features, performance and reliability of hard drives and alternative data storage technologies. Par...

Radiation-Hard Quartz Cerenkov Calorimeters

International Nuclear Information System (INIS)

Akgun, U.; Onel, Y.

2006-01-01

New generation hadron colliders are going to reach unprecedented energies and radiation levels. Quartz has been identified as a radiation-hard material that can be used for Cerenkov calorimeters of the future experiments. We report from the radiation hardness tests performed on quartz fibers, as well as the characteristics of the quartz fiber and plate Cerenkov calorimeters that have been built, designed, and proposed for the CMS experiment

Cladding tube materials for advanced nuclear facilities with closed fuel cycle

Energy Technology Data Exchange (ETDEWEB)

Bartosova, I. [Slovenska technicka univerzita v Bratislave, Fakulta elektrotechniky a informatiky, Ustav jadroveho a fyzikalneho inzinierstva, 81219 Bratislava (Slovakia)

2013-04-16

The paper is aimed on perspective materials for fuel cladding in advanced nuclear reactors. Samples of Eurofer and ODS Eurofer were studied by various techniques such as Positron Annihilation Lifetime Spectroscopy, Vickers Hardness and Coincidence Doppler Broadening. After studying the samples by these methods, we implanted them by Helium atoms to simulate irradiation damage. Samples were then remeasured by Positron Annihilation Lifetime Spectroscopy to determine the affect of implantation on its behavior. (authors)

State of the art in hard-on-hard bearings: how did we get here and what have we achieved?

Science.gov (United States)

Zywiel, Michael G; Sayeed, Siraj A; Johnson, Aaron J; Schmalzried, Thomas P; Mont, Michael A

2011-03-01

Total hip arthroplasty has shown excellent results in decreasing pain and improving function in patients with degenerative disease of the hip. Improvements in prosthetic materials, designs and implant fixation have now resulted in wear of the bearing surface being the limitation of this technology, and a number of hard-on-hard couples have been introduced to address this concern. The purpose of this article is to review the origins, development, survival rates and potential advantages and disadvantages of the following hard-on-hard bearings for total hip arthroplasty: metal-on-metal standard total hip arthroplasty; metal-on-metal hip resurfacing arthroplasty, ceramic-on-ceramic total hip arthroplasty; and ceramic-on-metal bearings. Improvements in the manufacturing of metal-on-metal bearings over the past 50 years have resulted in implants that provide low wear rates and allow for the use of large femoral heads. However, concerns remain regarding elevated serum metal ion levels, potential teratogenic effects and potentially devastating adverse local tissue reactions, whose incidence and pathogenesis remains unclear. Modern total hip resurfacing has shown excellent outcomes over 10 years in the hands of experienced surgeons. Current ceramic-on-ceramic bearings have demonstrated excellent survival with exceptionally low wear rates and virtually no local adverse effects. Concerns remain for insertional chipping, in vivo fracture and the variable incidence of squeaking. Contemporary ceramic-on-metal interfaces are in the early stages of clinical use, with little data reported to date. Hard-on-hard bearings for total hip arthroplasty have improved dramatically over the past 50 years. As bearing designs continue to improve with new and modified materials and improved manufacturing techniques, it is likely that the use of hard-on-hard bearings will continue to increase, especially in young and active patients.

Hard processes in hadronic interactions

International Nuclear Information System (INIS)

Satz, H.; Wang, X.N.

1995-01-01

Quantum chromodynamics is today accepted as the fundamental theory of strong interactions, even though most hadronic collisions lead to final states for which quantitative QCD predictions are still lacking. It therefore seems worthwhile to take stock of where we stand today and to what extent the presently available data on hard processes in hadronic collisions can be accounted for in terms of QCD. This is one reason for this work. The second reason - and in fact its original trigger - is the search for the quark-gluon plasma in high energy nuclear collisions. The hard processes to be considered here are the production of prompt photons, Drell-Yan dileptons, open charm, quarkonium states, and hard jets. For each of these, we discuss the present theoretical understanding, compare the resulting predictions to available data, and then show what behaviour it leads to at RHIC and LHC energies. All of these processes have the structure mentioned above: they contain a hard partonic interaction, calculable perturbatively, but also the non-perturbative parton distribution within a hadron. These parton distributions, however, can be studied theoretically in terms of counting rule arguments, and they can be checked independently by measurements of the parton structure functions in deep inelastic lepton-hadron scattering. The present volume is the work of Hard Probe Collaboration, a group of theorists who are interested in the problem and were willing to dedicate a considerable amount of their time and work on it. The necessary preparation, planning and coordination of the project were carried out in two workshops of two weeks' duration each, in February 1994 at CERn in Geneva andin July 1994 at LBL in Berkeley

Theory of hard diffraction and rapidity gaps

International Nuclear Information System (INIS)

Del Duca, V.

1995-06-01

In this talk we review the models describing the hard diffractive production of jets or more generally high-mass states in presence of rapidity gaps in hadron-hadron and lepton-hadron collisions. By rapidity gaps we mean regions on the lego plot in (pseudo)-rapidity and azimuthal angle where no hadrons are produced, between the jet(s) and an elastically scattered hadron (single hard diffraction) or between two jets (double hard diffraction). (orig.)

Seismic signals hard clipping overcoming

Science.gov (United States)

Olszowa, Paula; Sokolowski, Jakub

2018-01-01

In signal processing the clipping is understand as the phenomenon of limiting the signal beyond certain threshold. It is often related to overloading of a sensor. Two particular types of clipping are being recognized: soft and hard. Beyond the limiting value soft clipping reduces the signal real gain while the hard clipping stiffly sets the signal values at the limit. In both cases certain amount of signal information is lost. Obviously if one possess the model which describes the considered signal and the threshold value (which might be slightly more difficult to obtain in the soft clipping case), the attempt of restoring the signal can be made. Commonly it is assumed that the seismic signals take form of an impulse response of some specific system. This may lead to belief that the sine wave may be the most appropriate to fit in the clipping period. However, this should be tested. In this paper the possibility of overcoming the hard clipping in seismic signals originating from a geoseismic station belonging to an underground mine is considered. A set of raw signals will be hard-clipped manually and then couple different functions will be fitted and compared in terms of least squares. The results will be then analysed.

Structural and mechanical properties of ZnMgO nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Tosun, M. [Istanbul Technical University, Faculty of Mechanical Engineering, 34437, Gumussuyu, Istanbul (Turkey); Ataoglu, S. [Istanbul Technical University, Faculty of Civil Engineering, 34469, Maslak, Istanbul (Turkey); Istanbul Technical University, Earthquake Engineering and Disaster Management Institute, 34469, Maslak, Istanbul (Turkey); Arda, L., E-mail: lutfi.arda@bahcesehir.edu.tr [Bahcesehir University, Faculty of Arts and Sciences, Department of Mathematics and Computer Sciences, Ciragan Cad, Osmanpasa Mektebi Sok, 34349, Besiktas, Istanbul (Turkey); Ozturk, O.; Asikuzun, E. [Kastamonu University, Faculty of Arts and Sciences, Department of Physics, 37100, Kastamonu (Turkey); Akcan, D. [Bahcesehir University, Faculty of Arts and Sciences, Department of Mathematics and Computer Sciences, Ciragan Cad, Osmanpasa Mektebi Sok, 34349, Besiktas, Istanbul (Turkey); Cakiroglu, O. [Hasan Ali Yucel Education Faculty, Istanbul University, 34452, Beyazit, Istanbul (Turkey)

2014-01-10

This study reports the effect of annealing temperature on the structure and mechanical properties of Zn{sub 0.95}Mg{sub 0.05}O bulk samples by using digital Vickers microhardness tester, X-ray diffraction analysis, scanning electron microscopy and electron dispersive X-ray measurements. The samples were prepared using Zn and Mg based alkoxed by the sol–gel technique and annealed at various temperatures (500, 600, 700 and 800 °C). Vickers microhardness, elastic modulus, yield strength and fracture toughness values of Zn{sub 0.95}Mg{sub 0.05}O bulk samples were separately calculated and compared with each other. The experimental results of hardness measurements were analyzed using Meyer's law, Proportional Specimen Resistance (PSR) and Elastic/Plastic Deformation (EPD) models and Hays–Kendall (HK) approach. Finally, it was seen that HK approach is the most successful model for the microhardness analysis of these materials.

Rotation of hard particles in a soft matrix

Science.gov (United States)

Yang, Weizhu; Liu, Qingchang; Yue, Zhufeng; Li, Xiaodong; Xu, Baoxing

Soft-hard materials integration is ubiquitous in biological materials and structures in nature and has also attracted growing attention in the bio-inspired design of advanced functional materials, structures and devices. Due to the distinct difference in their mechanical properties, the rotation of hard phases in soft matrixes upon deformation has been acknowledged, yet is lack of theory in mechanics. In this work, we propose a theoretical mechanics framework that can describe the rotation of hard particles in a soft matrix. The rotation of multiple arbitrarily shaped, located and oriented particles with perfectly bonded interfaces in an elastic soft matrix subjected to a far-field tensile loading is established and analytical solutions are derived by using complex potentials and conformal mapping methods. Strong couplings and competitions of the rotation of hard particles among each other are discussed by investigating numbers, relative locations and orientations of particles in the matrix at different loading directions. Extensive finite element analyses are performed to validate theoretical solutions and good agreement of both rotation and stress field between them are achieved. Possible extensions of the present theory to non-rigid particles, viscoelastic matrix and imperfect bonding are also discussed. Finally, by taking advantage of the rotation of hard particles, we exemplify an application in a conceptual design of soft-hard material integrated phononic crystal and demonstrate that phononic band gaps can be successfully tuned with a high accuracy through the mechanical tension-induced rotation of hard particles. The present theory established herein is expected to be of immediate interests to the design of soft-hard materials integration based functional materials, structures and devices with tunable performance via mechanical rotation of hard phases.

Theory of hard diffraction and rapidity gaps

International Nuclear Information System (INIS)

Del Duca, V.

1996-01-01

In this talk we review the models describing the hard diffractive production of jets or more generally high-mass states in presence of rapidity gaps in hadron-hadron and lepton-hadron collisions. By rapidity gaps we mean regions on the lego plot in (pseudo)-rapidity and azimuthal angle where no hadrons are produced, between the jet(s) and an elastically scattered hadron (single hard diffraction) or between two jets (double hard diffraction). copyright 1996 American Institute of Physics

Hard X-ray studies on the Castor tokamak

International Nuclear Information System (INIS)

Mlynar, J.

1990-04-01

The electron runaway processes in tokamaks are discussed with regard to hard X radiation measurements. The origin and confinement of runaway electrons, their bremsstrahlung spectra and the influence of lower hybrid current drive on the distribution of high-energy electrons are analyzed for the case of the Castor tokamak. The hard X-ray spectrometer designed for the Castor tokamak is also described and preliminary qualitative results of hard X-ray measurements are presented. The first series of integral measurements made it possible to map the azimuthal dependence of the hard X radiation

Spark plasma sintered bismuth telluride-based thermoelectric materials incorporating dispersed boron carbide

Energy Technology Data Exchange (ETDEWEB)

Williams, H.R., E-mail: hugo.williams@leicester.ac.uk [Department of Engineering, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Ambrosi, R.M. [Space Research Centre, Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Chen, K. [School of Engineering and Materials Science, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom); Friedman, U. [Department of Engineering, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Ning, H.; Reece, M.J. [School of Engineering and Materials Science, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom); Robbins, M.C.; Simpson, K. [European Thermodynamics Ltd., 8 Priory Business Park, Wistow Road, Kibworth LE8 0R (United Kingdom); Stephenson, K. [European Space Agency, ESTEC TEC-EP, Keplerlaan 1, 2201AZ Noordwijk (Netherlands)

2015-03-25

Highlights: • Nano-B{sub 4}C reinforced Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} p-type thermoelectric produced by SPS. • Addition of B{sub 4}C up to 0.2 vol% to SPS’d material has little effect on zT. • Vickers hardness improved by 27% by adding 0.2 vol% B{sub 4}C. • Fracture toughness of SPS material: K{sub IC} = 0.80 MPa m{sup 1/2} by SEVNB. • Mechanical properties much better than commercial directionally solidified material. - Abstract: The mechanical properties of bismuth telluride based thermoelectric materials have received much less attention in the literature than their thermoelectric properties. Polycrystalline p-type Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} materials were produced from powder using spark plasma sintering (SPS). The effects of nano-B{sub 4}C addition on the thermoelectric performance, Vickers hardness and fracture toughness were measured. Addition of 0.2 vol% B{sub 4}C was found to have little effect on zT but increased hardness by approximately 27% when compared to polycrystalline material without B{sub 4}C. The K{sub IC} fracture toughness of these compositions was measured as 0.80 MPa m{sup 1/2} by Single-Edge V-Notched Beam (SEVNB). The machinability of polycrystalline materials produced by SPS was significantly better than commercially available directionally solidified materials because the latter is limited by cleavage along the crystallographic plane parallel to the direction of solidification.

Thermal stability of a highly-deformed warm-rolled tungsten plate in the temperature range 1100–1250 °C

Energy Technology Data Exchange (ETDEWEB)

Alfonso, A., E-mail: aalz@dtu.dk [Section of Materials and Surface Engineering, Department of Mechanical Engineering, Technical University of Denmark, 2800 Lyngby (Denmark); Sino-Danish Center for Education and Research, Denmark and China (Denmark); Juul Jensen, D. [Danish-Chinese Center for Nanometals, Section of Materials Science and Advanced Characterization, Department of Wind Energy, Technical University of Denmark, Risø Campus, 4000 Roskilde (Denmark); Sino-Danish Center for Education and Research, Denmark and China (Denmark); Luo, G.-N. [Fusion Reactor Materials Science and Technology Division, Institute of Plasma Physics, Chinese Academy of Sciences, 230031 Hefei, Anhui (China); Sino-Danish Center for Education and Research, Denmark and China (Denmark); Pantleon, W. [Section of Materials and Surface Engineering, Department of Mechanical Engineering, Technical University of Denmark, 2800 Lyngby (Denmark); Association EURATOM-DTU (Denmark); Sino-Danish Center for Education and Research, Denmark and China (Denmark)

2015-10-15

Highlights: • Annealing kinetics of highly-deformed tungsten up to 190 h between 1100 °C and 1250 °C. • Loss of mechanical strength characterized by Vickers hardness measurements. • Two distinct stages of recovery and recrystallization identified and described by established models. • Activation energy of recrystallization lower than after moderate deformation of tungsten. • Comparable to activation energy of grain boundary diffusion due to abundance of low angle boundaries. - Abstract: Pure tungsten is considered as armor material for the most critical parts of fusion reactors (i.e. the divertor and the first wall), among other reasons due to its high melting point (3422 °C) and recrystallization temperature. The thermal stability of a pure tungsten plate warm-rolled to a high plastic strain by 90% thickness reduction was investigated by isothermal annealing for up to 190 h in the temperature range between 1100 °C and 1250 °C. Vickers hardness testing allowed tracking the changes in mechanical properties caused by recovery and recrystallization. The hardness evolution could be rationalized in terms of a logarithmic recovery kinetics and a Johnson–Mehl–Avrami–Kolmogorov recrystallization kinetics accounting for an incubation time of recrystallization. The observed time spans for recrystallization and the corresponding recrystallization activation energy for this highly deformed plate suggest that large plastic deformations (e.g. applied during shaping) are only suitable to produce tungsten components to be used at relatively low temperatures (up to 900 °C for a 2 years lifespan). Higher operation temperatures will lead to fast degradation of the microstructure during operation.

Thermal stability of a highly-deformed warm-rolled tungsten plate in the temperature range 1100–1250 °C

International Nuclear Information System (INIS)

Alfonso, A.; Juul Jensen, D.; Luo, G.-N.; Pantleon, W.

2015-01-01

Highlights: • Annealing kinetics of highly-deformed tungsten up to 190 h between 1100 °C and 1250 °C. • Loss of mechanical strength characterized by Vickers hardness measurements. • Two distinct stages of recovery and recrystallization identified and described by established models. • Activation energy of recrystallization lower than after moderate deformation of tungsten. • Comparable to activation energy of grain boundary diffusion due to abundance of low angle boundaries. - Abstract: Pure tungsten is considered as armor material for the most critical parts of fusion reactors (i.e. the divertor and the first wall), among other reasons due to its high melting point (3422 °C) and recrystallization temperature. The thermal stability of a pure tungsten plate warm-rolled to a high plastic strain by 90% thickness reduction was investigated by isothermal annealing for up to 190 h in the temperature range between 1100 °C and 1250 °C. Vickers hardness testing allowed tracking the changes in mechanical properties caused by recovery and recrystallization. The hardness evolution could be rationalized in terms of a logarithmic recovery kinetics and a Johnson–Mehl–Avrami–Kolmogorov recrystallization kinetics accounting for an incubation time of recrystallization. The observed time spans for recrystallization and the corresponding recrystallization activation energy for this highly deformed plate suggest that large plastic deformations (e.g. applied during shaping) are only suitable to produce tungsten components to be used at relatively low temperatures (up to 900 °C for a 2 years lifespan). Higher operation temperatures will lead to fast degradation of the microstructure during operation.

Pulse generator for bias materials in the plasma immerse ion implantation process; Generador de pulsos para polarizar materiales en el proceso de implantacion de iones inmersos en plasma

Energy Technology Data Exchange (ETDEWEB)

Lopez Callegas, Regulo; Valencia Alvarado, Raul; Munoz Castro, Arturo Eduardo; Godoy Cabrera, Oscar Gerardo [Instituto Nacional de Investigaciones Nucleares, Mexico D.F. (Mexico); Moreno Saavedra, Hilda; Gonzalez Colin, Mireya; Mariano Escamilla, Hector Fernando [Instituto Tecnologico de Toluca, Estado de Mexico (Mexico)

2003-10-15

The 0-10 kV pulse generator has been designed, with 100 {mu}s duration and 1-100 Hz frequencies ranges. The use of the pulse generator is in the plasma immersed ion implantation technique (P III). The process was realized in 304 austenitic stainless steel, the results were analyzed by: SEM, X-rays diffraction and hardness Vickers. The hardness was increased due to the efficiency of the pulse generator and P III process, the results obtained showed that the nitrogen inside the stainless steel was implanted and besides some nitrides was formed and therefore the hardness was increased. Also, the more adequate work pressure was determined to carry out the P III process. [Spanish] Se presenta el diseno de un generador de pulsos de alto voltaje con amplitudes controladas de hasta 10 kV, la duracion maxima de los pulsos es del orden de los 100 {mu}s y frecuencia de repeticion en el intervalo de 1-100 Hz. La aplicacion de este generador de pulsos es para el proceso de implantacion de iones en materiales inmersos en plasmas (PIII). Los analisis hechos a los aceros austeniticos cedula 304 mediante microscopia electronica de barrido, difraccion de rayos X y dureza Vickers, muestran la eficiencia obtenida con el generador de pulsos en el proceso PIII, debido a que en el acero inoxidable se presenta un incremento en el nitrogeno y conformacion de algunos nitruros, lo cual da lugar al incremento de la dureza. Asimismo, se determino la presion de trabajo mas adecuada para llevar a cabo el proceso PIII.

Hard exclusive QCD processes

Energy Technology Data Exchange (ETDEWEB)

Kugler, W.

2007-01-15

Hard exclusive processes in high energy electron proton scattering offer the opportunity to get access to a new generation of parton distributions, the so-called generalized parton distributions (GPDs). This functions provide more detailed informations about the structure of the nucleon than the usual PDFs obtained from DIS. In this work we present a detailed analysis of exclusive processes, especially of hard exclusive meson production. We investigated the influence of exclusive produced mesons on the semi-inclusive production of mesons at fixed target experiments like HERMES. Further we give a detailed analysis of higher order corrections (NLO) for the exclusive production of mesons in a very broad range of kinematics. (orig.)

Soft and hard pomerons

International Nuclear Information System (INIS)

Maor, Uri; Tel Aviv Univ.

1995-09-01

The role of s-channel unitarity screening corrections, calculated in the eikonal approximation, is investigated for soft Pomeron exchange responsible for elastic and diffractive hadron scattering in the high energy limit. We examine the differences between our results and those obtained from the supercritical Pomeron-Regge model with no such corrections. It is shown that screening saturation is attained at different scales for different channels. We then proceed to discuss the new HERA data on hard (PQCD) Pomeron diffractive channels and discuss the relationship between the soft and hard Pomerons and the relevance of our analysis to this problem. (author). 18 refs, 9 figs, 1 tab

Soft And Hard Skills of Social Worker

OpenAIRE

HANTOVÁ, Libuše

2011-01-01

The work deals with soft and hard skills relevant to the profession of social worker. The theoretical part at first evaluates and analyzes important soft and hard skills necessary for people working in the field of social work. Then these skills are compared. The practical part illustrates the use of soft and hard skills in practice by means of model scenes and deals with the preferences in three groups of people ? students of social work, social workers and people outside the sphere, namely ...

7 CFR 201.57 - Hard seeds.

Science.gov (United States)

2010-01-01

... REGULATIONS Germination Tests in the Administration of the Act § 201.57 Hard seeds. Seeds which remain hard at the end of the prescribed test because they have not absorbed water, due to an impermeable seed coat... percentage of germination. For flatpea, continue the swollen seed in test for 14 days when germinating at 15...

Microstructures, hardness and bioactivity of hydroxyapatite coatings deposited by direct laser melting process

International Nuclear Information System (INIS)

Tlotleng, Monnamme; Akinlabi, Esther; Shukla, Mukul; Pityana, Sisa

2014-01-01

Hydroxyapatite (HAP) coatings on bioinert metals such as Ti–6Al–4V are necessary for biomedical applications. Together, HAP and Ti–6Al–4V are biocompatible and bioactive. The challenges of depositing HAP on Ti–6Al–4V with traditional thermal spraying techniques are well founded. In this paper, HAP was coated on Ti–6Al–4V using direct laser melting (DLM) process. This process, unlike the traditional coating processes, is able to achieve coatings with good metallurgical bonding and little dilution. The microstructural and mechanical properties, chemical composition and bio-activities of the produced coatings were studied with optical microscopy, scanning electron microscope equipped with energy dispersive X-ray spectroscopy, and Vickers hardness machine, and by immersion test in Hanks' solution. The results showed that the choice of the laser power has much influence on the evolving microstructure, the mechanical properties and the retainment of HAP on the surface of the coating. Also, the choice of laser power of 750 W led to no dilution. The microhardness results inferred a strong intermetallic–ceramic interfacial bonding; which meant that the 750 W coating could survive long in service. Also, the coating was softer at the surface and stronger in the heat affected zones. Hence, this process parameter setting can be considered as an optimal setting. The soak tests revealed that the surface of the coating had unmelted crystals of HAP. The CaP ratio conducted on the soaked coating was 2.00 which corresponded to tetra calcium phosphate. This coating seems attractive for metallic implant applications. - Highlights: • Characteristics of HAP coatings produced on Ti-6Al-4V achieved with direct laser melting are reported. • Optimal process parameters necessary to achieve biocompatible coating are reported. • The SEM micrograph of the soaked HAP coating revealed partially melted crystals of HAP. • The HAP coating was retained at the surface of

Microstructures, hardness and bioactivity of hydroxyapatite coatings deposited by direct laser melting process

Energy Technology Data Exchange (ETDEWEB)

Tlotleng, Monnamme, E-mail: MTlotleng@csir.co.za [Laser Materials Processing Group, National Laser Center CSIR, Pretoria 0001 (South Africa); Department of Mechanical Engineering Science, University of Johannesburg, Auckland Park, Kingsway Campus, Johannesburg 2006 (South Africa); Akinlabi, Esther [Department of Mechanical Engineering Science, University of Johannesburg, Auckland Park, Kingsway Campus, Johannesburg 2006 (South Africa); Shukla, Mukul [Department of Mechanical Engineering Technology, University of Johannesburg, Doornfontein Campus, Johannesburg 2006 (South Africa); Department of Mechanical Engineering, MNNIT, Allahabad, UP 211004 (India); Pityana, Sisa [Laser Materials Processing Group, National Laser Center CSIR, Pretoria 0001 (South Africa); Department of Chemical and Metallurgical Engineering, Tshwane University of Technology, Pretoria 0001 (South Africa)

2014-10-01

Hydroxyapatite (HAP) coatings on bioinert metals such as Ti–6Al–4V are necessary for biomedical applications. Together, HAP and Ti–6Al–4V are biocompatible and bioactive. The challenges of depositing HAP on Ti–6Al–4V with traditional thermal spraying techniques are well founded. In this paper, HAP was coated on Ti–6Al–4V using direct laser melting (DLM) process. This process, unlike the traditional coating processes, is able to achieve coatings with good metallurgical bonding and little dilution. The microstructural and mechanical properties, chemical composition and bio-activities of the produced coatings were studied with optical microscopy, scanning electron microscope equipped with energy dispersive X-ray spectroscopy, and Vickers hardness machine, and by immersion test in Hanks' solution. The results showed that the choice of the laser power has much influence on the evolving microstructure, the mechanical properties and the retainment of HAP on the surface of the coating. Also, the choice of laser power of 750 W led to no dilution. The microhardness results inferred a strong intermetallic–ceramic interfacial bonding; which meant that the 750 W coating could survive long in service. Also, the coating was softer at the surface and stronger in the heat affected zones. Hence, this process parameter setting can be considered as an optimal setting. The soak tests revealed that the surface of the coating had unmelted crystals of HAP. The CaP ratio conducted on the soaked coating was 2.00 which corresponded to tetra calcium phosphate. This coating seems attractive for metallic implant applications. - Highlights: • Characteristics of HAP coatings produced on Ti-6Al-4V achieved with direct laser melting are reported. • Optimal process parameters necessary to achieve biocompatible coating are reported. • The SEM micrograph of the soaked HAP coating revealed partially melted crystals of HAP. • The HAP coating was retained at the surface of

Hard scattering and a diffractive trigger

International Nuclear Information System (INIS)

Berger, E.L.; Collins, J.C.; Soper, D.E.; Sterman, G.

1986-02-01

Conclusions concerning the properties of hard scattering in diffractively produced systems are summarized. One motivation for studying diffractive hard scattering is to investigate the interface between Regge theory and perturbative QCD. Another is to see whether diffractive triggering can result in an improvement in the signal-to-background ratio of measurements of production of very heavy quarks. 5 refs

Complex technique for materials hardness measurement

Energy Technology Data Exchange (ETDEWEB)

Krashchenko, V P; Oksametnaya, O B

1984-01-01

A review of existing methods of measurement of material hardness in national and foreign practice has been made. A necessity of improving the technique of material hardness measurement in a wide temperature range and insuring load change with indenting, continuity of imprint application, smooth changing of temperatures along a sample length, and deformation rate control has been noted.

Seismic loads in modularized and unmodularized large pools located on hard or intermediate hard sites

Energy Technology Data Exchange (ETDEWEB)

Dong, R G [California Univ., Livermore (USA). Lawrence Livermore Lab.

1977-12-01

To augment the present capacity of pools for storing spent nuclear fuel elements, pools larger than those in current use are being planned. These pools may or may not be modularized into cells. Because of the large size of the pools, seismic loads are of significant interest. In particular, the effects of modularization and site hardness are of concern. The study presented in this paper reveals that modularization is generally unfavourable, because it creates the option of leaving one or more cells empty which in turn results in higher structural loads. The wall which separates a filled cell from an empty cell, or the wall which bears against earth on one side and faces an empty cell on the other, becomes very highly stressed. For the particular pool geometries examined, a hard site is generally preferred over an intermediate hard site in terms of structural loads.

Dualism of precipitation morphology in high strength low alloy steel

International Nuclear Information System (INIS)

Chih-Yuan, Chen; Chien-Chon, Chen; Jer-Ren, Yang

2015-01-01

While the role of microalloying elements on precipitation strengthening in ferrite matrix during austenite/ferrite transformation is quite clear, some uncertainty still exists concerning the variability of the microhardness distribution of ferrite grains in the isothermal holding condition. The objective of the present study was to clarify the intrinsic characteristics of carbide precipitation morphology in the ferrite matrix under different processing temperatures and times and to correlate it with austenite decomposition kinetics to elucidate why a large microhardness distribution occurs at low isothermal holding temperature. Better understanding of carbide precipitation behavior can help researchers to determine the root cause of variation in microhardness distribution, which would allow metallurgists to produce high quality steels. Measurement with a Vickers hardness indenter revealed that, in specimens isothermally held at 625 °C, the range of Vickers hardness distribution was 240–420 after 5 min of isothermal holding, and 270–340 after 60 min. For specimens isothermally held at 725 °C, the range of Vickers hardness distribution was 200–330 for 5 min of isothermal holding, and 200–250 for 60 min. Therefore, the average microhardness decreased with the isothermal holding temperature and time, and a larger range of distribution occurred with short isothermal holding times. Transmission electron microscopy (TEM) images showed that interface precipitation and random precipitation can occur within the same ferrite grain. The reason is that the austenite decomposition rate varies with transformation temperature and time. An excessively fast austenite/ferrite interface movement velocity, which usually happens in small ferrite grains, would cause these ferrite grains with microalloying elements to exceed their solubility. Furthermore, these microalloying elements will be precipitated randomly after isothermal holding at longer times. Consequently, a large

Dualism of precipitation morphology in high strength low alloy steel

Energy Technology Data Exchange (ETDEWEB)

Chih-Yuan, Chen, E-mail: chen6563@gmail.com [Department of Energy Engineering, National United University, Miaoli 36003, Taiwan (China); Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Chien-Chon, Chen [Department of Energy Engineering, National United University, Miaoli 36003, Taiwan (China); Jer-Ren, Yang, E-mail: jryang@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

2015-02-25

While the role of microalloying elements on precipitation strengthening in ferrite matrix during austenite/ferrite transformation is quite clear, some uncertainty still exists concerning the variability of the microhardness distribution of ferrite grains in the isothermal holding condition. The objective of the present study was to clarify the intrinsic characteristics of carbide precipitation morphology in the ferrite matrix under different processing temperatures and times and to correlate it with austenite decomposition kinetics to elucidate why a large microhardness distribution occurs at low isothermal holding temperature. Better understanding of carbide precipitation behavior can help researchers to determine the root cause of variation in microhardness distribution, which would allow metallurgists to produce high quality steels. Measurement with a Vickers hardness indenter revealed that, in specimens isothermally held at 625 °C, the range of Vickers hardness distribution was 240–420 after 5 min of isothermal holding, and 270–340 after 60 min. For specimens isothermally held at 725 °C, the range of Vickers hardness distribution was 200–330 for 5 min of isothermal holding, and 200–250 for 60 min. Therefore, the average microhardness decreased with the isothermal holding temperature and time, and a larger range of distribution occurred with short isothermal holding times. Transmission electron microscopy (TEM) images showed that interface precipitation and random precipitation can occur within the same ferrite grain. The reason is that the austenite decomposition rate varies with transformation temperature and time. An excessively fast austenite/ferrite interface movement velocity, which usually happens in small ferrite grains, would cause these ferrite grains with microalloying elements to exceed their solubility. Furthermore, these microalloying elements will be precipitated randomly after isothermal holding at longer times. Consequently, a large

Micro-computer cards for hard industrial environment

Energy Technology Data Exchange (ETDEWEB)

Breton, J M

1984-03-15

Approximately 60% of present or future distributed systems have, or will have, operational units installed in hard environments. In these applications, which include canalization and industrial motor control, robotics and process control, systems must be easily applied in environments not made for electronic use. The development of card systems in this hard industrial environment, which is found in petrochemical industry and mines is described. National semiconductor CIM card system CMOS technology allows the real time micro computer application to be efficient and functional in hard industrial environments.

Transport coefficients and mechanical response in hard-disk colloidal suspensions

International Nuclear Information System (INIS)

Zhang Bo-Kai; Ma Yu-Qiang; Li Jian; Chen Kang; Tian Wen-De

2016-01-01

We investigate the transport properties and mechanical response of glassy hard disks using nonlinear Langevin equation theory. We derive expressions for the elastic shear modulus and viscosity in two dimensions on the basis of thermal-activated barrier-hopping dynamics and mechanically accelerated motion. Dense hard disks exhibit phenomena such as softening elasticity, shear-thinning of viscosity, and yielding upon deformation, which are qualitatively similar to dense hard-sphere colloidal suspensions in three dimensions. These phenomena can be ascribed to stress-induced “landscape tilting”. Quantitative comparisons of these phenomena between hard disks and hard spheres are presented. Interestingly, we find that the density dependence of yield stress in hard disks is much more significant than in hard spheres. Our work provides a foundation for further generalizing the nonlinear Langevin equation theory to address slow dynamics and rheological behavior in binary or polydisperse mixtures of hard or soft disks. (rapid communication)

Comparison Study on Additive Manufacturing (AM) and Powder Metallurgy (PM) AlSi10Mg Alloys

Science.gov (United States)

Chen, B.; Moon, S. K.; Yao, X.; Bi, G.; Shen, J.; Umeda, J.; Kondoh, K.

2018-02-01

The microstructural and mechanical properties of AlSi10Mg alloys fabricated by additive manufacturing (AM) and powder metallurgy (PM) routes were investigated and compared. The microstructures were examined by scanning electron microscopy assisted with electron-dispersive spectroscopy. The crystalline features were studied by x-ray diffraction and electron backscatter diffraction. Room-temperature tensile tests and Vickers hardness measurements were performed to characterize the mechanical properties. It was found that the AM alloy had coarser Al grains but much finer Si precipitates compared with the PM alloy. Consequently, the AM alloy showed more than 100% increment in strength and hardness compared with the PM alloy due to the presence of ultrafine forms of Si, while exhibiting moderate ductility.

CMOS optimization for radiation hardness

International Nuclear Information System (INIS)

Derbenwick, G.F.; Fossum, J.G.

1975-01-01

Several approaches to the attainment of radiation-hardened MOS circuits have been investigated in the last few years. These have included implanting the SiO 2 gate insulator with aluminum, using chrome-aluminum layered gate metallization, using Al 2 O 3 as the gate insulator, and optimizing the MOS fabrication process. Earlier process optimization studies were restricted primarily to p-channel devices operating with negative gate biases. Since knowledge of the hardness dependence upon processing and design parameters is essential in producing hardened integrated circuits, a comprehensive investigation of the effects of both process and design optimization on radiation-hardened CMOS integrated circuits was undertaken. The goals are to define and establish a radiation-hardened processing sequence for CMOS integrated circuits and to formulate quantitative relationships between process and design parameters and the radiation hardness. Using these equations, the basic CMOS design can then be optimized for radiation hardness and some understanding of the basic physics responsible for the radiation damage can be gained. Results are presented

Enhanced properties of nanostructured TiO2-graphene composites by rapid sintering

Science.gov (United States)

Shon, In-Jin; Yoon, Jin-Kook; Hong, Kyung-Tae

2018-01-01

Despite of many attractive properties of TiO2, the drawback of TiO2 ceramic is low fracture toughness for widely industrial application. The method to improve the fracture toughness and hardness has been reported by addition of reinforcing phase to fabricate a nanostructured composite. In this regard, graphene has been evaluated as an ideal second phase in ceramics. Nearly full density of nanostructured TiO2-graphene composite was achieved within one min using pulsed current activated sintering. The effect of graphene on microstructure, fracture toughness and hardness of TiO2-graphene composite was evaluated using Vickers hardness tester and field emission scanning electron microscopy. The grain size of TiO2 in the TiO2-x vol% (x = 0, 1, 3, and 5) graphene composite was greatly reduced with increase in addition of graphene. Both hardness and fracture toughness of TiO2-graphene composites simultaneously increased in the addition of graphene.

Characteristics of thermochemical treated EN10090 X50 steel

International Nuclear Information System (INIS)

Schmitz, S.; Graf, K.; Scheid, A.; Moreno, A.

2014-01-01

EN10090 X50 steel is commonly used for engine valves to withstand severe operation conditions involving high temperature and corrosion from fuel and combustion gas. Usually, to enhance wear performance, valves undergo nitriding thermochemical treatment by salt baths. The aim of this work is to produce diffusion layers at least 20μm thick with hardness higher than 700HV by plasma surface treatment with no continuous compounds layer using nitrogen and methane based atmospheres. Samples were characterized by laser Confocal and scanning electron microscopy, X-ray diffraction and Vickers hardness. Salt bath treatment induced formation of undesirable compounds layer at the surface and a diffusion layer thicker than 40μm, with hardness arising 1280HV_0_,_0_1_0. Plasma surface treatment produced diffusion layer thicker than 40μm with no continuous compounds layer and mean hardness varying from 750 to 960HV_0_,_0_1_0. (author)

Mechanical properties of TiN films deposited by changed-pressure r.f. sputtering

International Nuclear Information System (INIS)

Kubo, Y.; Hashimoto, M.

1991-01-01

TiN was deposited onto glass, stainless steel and cemented carbide by r.f. magnetron sputtering. The mechanical properties of TiN such as hardness, internal stress and adhesion were assessed by the Vickers microhardness test, the bending method and the modified scratch test. It was found that the operating pressure during sputtering deposition strongly affects these mechanical properties. As the operating pressure is increased beyond 0.6-0.7 Pa, the adhesion of TiN films onto the substrate increases enormously, but the hardness decreases owing to the release of the high compressive stress in the film. Therefore changing the pressure from high to low during deposition could be a good way of optimizing both hardness and adhesion. The effectiveness of this changed-pressure process was experimentally verified by cutting tests using TiN-coated cemented carbide tools. This process will be applicable to any other hard coating materials having high compressive stresses. (orig.)

The effect of fiber laser parameters on microhardness and microstructure of duplex stainless steel

Directory of Open Access Journals (Sweden)

Mohammed Ghusoon R.

2017-01-01

Full Text Available An investigation was implement to study the influence of laser power, and speed of the welding on hardness, microstructure, and penetration of laser welding bead on plate duplex stainless steel, which is not exhibited so far. A fiber laser was selected for welding duplex stainless steel sheet with 2 mm thickness. Then, optical microscope (OM was used in the morphologic observation of cross section, penetration depth, and bead width. Microhardness of the welded sheet was measured using Vickers hardness. Profiles of hardness and microstructure were utilized to discriminate welding line and to propose superior welding parameters. The experimental results displayed that, a good quality of duplex steel welds can be acquired when a suitable fiber laser welding parameters were selected. It was found that microhardness profiles showed a rise in the hardness of the weld and heat-affected zones as the solidification process proceeds rapidly. Additionally, the crystal solidification process induced by the fiber laser welding was schematically clarified and systematically exposed.

Novel hard compositions and methods of preparation

Science.gov (United States)

Sheinberg, H.

1983-08-23

Novel very hard compositions of matter are prepared by using in all embodiments only a minor amount of a particular carbide (or materials which can form the carbide in situ when subjected to heat and pressure); and no strategic cobalt is needed. Under a particular range of conditions, densified compositions of matter of the invention are prepared having hardnesses on the Rockwell A test substantially equal to the hardness of pure tungsten carbide and to two of the hardest commercial cobalt-bonded tungsten carbides. Alternately, other compositions of the invention which have slightly lower hardnesses than those described above in one embodiment also possess the advantage of requiring no tungsten and in another embodiment possess the advantage of having a good fracture toughness value. Photomicrographs show that the shapes of the grains of the alloy mixture with which the minor amount of carbide (or carbide-formers) is mixed are radically altered from large, rounded to small, very angular by the addition of the carbide. Superiority of one of these hard compositions of matter over cobalt-bonded tungsten carbide for ultra-high pressure anvil applications was demonstrated. 3 figs.

Study of Cu-Al-Zn alloys hardness temperature dependence

International Nuclear Information System (INIS)

Kurmanova, D.T.; Skakov, M.K.; Melikhov, V.D.

2001-01-01

In the paper the results of studies for the Cu-Al-Zn ternary alloys hardness temperature dependence are presented. The method of 'hot hardness' has been used during study of the solid state phase transformations and under determination of the hot stability boundaries. Due to the samples brittleness a hardness temperature dependence definition is possible only from 350-400 deg. C. Sensitivity of the 'hot hardness' method is decreasing within high plasticity range, so the measurements have been carried out only up to 700-800 deg. C. It is shown, that the alloys hardness dependence character from temperature is close to exponential one within the certain structure modification existence domain

Synthesis, Structure, and Properties of Refractory Hard-Metal Borides

Science.gov (United States)

Lech, Andrew Thomas

As the limits of what can be achieved with conventional hard compounds, such as tungsten carbide, are nearing reach, super-hard materials are an area of increasing industrial interest. The refractory hard metal borides, such as ReB2 and WB4, offer an increasingly attractive alternative to diamond and cubic boron nitride as a next-generation tool material. In this Thesis, a thorough discussion is made of the progress achieved by our laboratory towards understanding the synthesis, structure, and properties of these extremely hard compounds. Particular emphasis is placed on structural manipulation, solid solution formation, and the unique crystallographic manifestations of what might also be called "super-hard metals".

Curing characteristics of flowable and sculptable bulk-fill composites

OpenAIRE

Miletic, Vesna; Pongpruenska, Pong; De Munck, Jan; Brooks, Neil R; Van Meerbeek, Bart

2016-01-01

OBJECTIVES: The aim of this study was to determine and correlate the degree of conversion (DC) with Vickers hardness (VH) and translucency parameter (TP) with the depth of cure (DoC) of five bulk-fill composites. MATERIALS AND METHODS: Six specimens per group, consisting of Tetric EvoCeram Bulk Fill ("TEC Bulk," Ivoclar Vivadent), SonicFill (Kerr), SDR Smart Dentin Replacement ("SDR," Dentsply), Xenius base ("Xenius," StickTech; commercialized as EverX Posterior, GC), Filtek Bul...

Visual inspection technology in the hard disc drive industry

CERN Document Server

Muneesawang, Paisarn

2015-01-01

A presentation of the use of computer vision systems to control manufacturing processes and product quality in the hard disk drive industry. Visual Inspection Technology in the Hard Disk Drive Industry is an application-oriented book borne out of collaborative research with the world's leading hard disk drive companies. It covers the latest developments and important topics in computer vision technology in hard disk drive manufacturing, as well as offering a glimpse of future technologies.

Characterization of nickel-based C276 alloy coatings by Plasma Transferred Arc (PTA) on different steel substrates

International Nuclear Information System (INIS)

Ferreira, L.S.; Graf, K.; Scheid, A.

2014-01-01

Nickel-based coatings by plasma transferred arc (PTA) for protection of components are widely applied to withstand operations under corrosion in different media. This paper characterized Nickel-based C276 alloy coatings obtained by Plasma Transferred Arc (PTA) on two different substrates, AISI 316L and API 5L X70 steels, correlating their features to hardness. Coatings were deposited utilizing three different intensity current levels, 120, 150 and 180 A and were characterized by optical, Laser confocal and scanning electron microscopy and X-ray diffraction. Vickers hardness profiles on transversal section were carried out. Produced coatings exhibited a microstructure of austenite (FCC) dendrites with interdendritic regions with carbides. Dilution levels from 4,9 to 41,5 % leaded to hardness ranging from 225 to 283 HV_0_,_5, showing coatings dependence on intensity current level and substrate. (author)

High energy ions and energetic plasma irradiation effects on aluminum in a Filippov-type plasma focus

Energy Technology Data Exchange (ETDEWEB)

Roshan, M.V. [National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616 (Singapore)], E-mail: mroshan20@yahoo.com; Rawat, R.S. [National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616 (Singapore); Babazadeh, A.R.; Emami, M.; Sadat Kiai, S.M. [Plasma Physics Research Center, AEOI, 14155-1339 Tehran (Iran, Islamic Republic of); Verma, R.; Lin, J.J.; Talebitaher, A.R.; Lee, P.; Springham, S.V. [National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616 (Singapore)

2008-12-30

High energy ions and energetic plasma irradiation of aluminum cathode inserts have been accomplished in nitrogen and argon filled plasma focus device. The Filippov-type plasma focus facility, Dena, with 288 {mu}F capacitor bank and charging voltage of 25 kV (90 kJ maximum storage energy) was first optimized for strong ion beam generation for nitrogen and argon gases by maximizing hard X-ray emission efficiency. X-ray diffraction analysis as well as scanning electron microscopy along with energy dispersive X-ray spectroscopy carried out to study the structural, morphological and compositional profile of the treated samples. Change in preferred orientation, emergence of meta-stable phases, generation of copper micro-droplets, and production of cracks across the sample are demonstrated and discussed. The micro-hardness measurements in Vickers scale reveal that after ion irradiation, the surface hardness of samples is reduced.

Characterization of nickel-based C276 alloy coatings by Plasma Transferred Arc (PTA) on different steel substrates

Energy Technology Data Exchange (ETDEWEB)

Ferreira, L.S.; Graf, K.; Scheid, A., E-mail: scheid@ufpr.br [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil)

2014-07-01

Nickel-based coatings by plasma transferred arc (PTA) for protection of components are widely applied to withstand operations under corrosion in different media. This paper characterized Nickel-based C276 alloy coatings obtained by Plasma Transferred Arc (PTA) on two different substrates, AISI 316L and API 5L X70 steels, correlating their features to hardness. Coatings were deposited utilizing three different intensity current levels, 120, 150 and 180 A and were characterized by optical, Laser confocal and scanning electron microscopy and X-ray diffraction. Vickers hardness profiles on transversal section were carried out. Produced coatings exhibited a microstructure of austenite (FCC) dendrites with interdendritic regions with carbides. Dilution levels from 4,9 to 41,5 % leaded to hardness ranging from 225 to 283 HV{sub 0,5}, showing coatings dependence on intensity current level and substrate. (author)

Hard template synthesis of metal nanowires

Science.gov (United States)

Kawamura, Go; Muto, Hiroyuki; Matsuda, Atsunori

2014-11-01

Metal nanowires (NWs) have attracted much attention because of their high electron conductivity, optical transmittance and tunable magnetic properties. Metal NWs have been synthesized using soft templates such as surface stabilizing molecules and polymers, and hard templates such as anodic aluminum oxide, mesoporous oxide, carbon nanotubes. NWs prepared from hard templates are composites of metals and the oxide/carbon matrix. Thus, selecting appropriate elements can simplify the production of composite devices. The resulting NWs are immobilized and spatially arranged, as dictated by the ordered porous structure of the template. This avoids the NWs from aggregating, which is common for NWs prepared with soft templates in solution. Herein, the hard template synthesis of metal NWs is reviewed, and the resulting structures, properties and potential applications are discussed.

Why Are Drugs So Hard to Quit?

Medline Plus

Full Text Available ... Quitting drugs is hard because addiction is a brain disease. Your brain is like a control tower that sends out ... and choices. Addiction changes the signals in your brain and makes it hard to feel OK without ...

Hard diffraction and small-x

International Nuclear Information System (INIS)

Anon.

1995-01-01

In the United States, phrases such as ''small-x evolution'', ''the BFKL Pomeron'', ''deep-inelastic rapiditygap events'' and ''hard-diffraction'' do not generate the same intensity of discussion amongst high-energy physicists that they do in Europe. However, for three days in the fall such discussion filled the air at Fermilab. The ''2nd Workshop on Small-x and Diffractive Physics at the Tevatron'' was a review of the rapid theoretical and experimental progress taking place in this field. Although Quantum Chromo-dynamics (QCD) has been established as the theory of strong interactions for twenty years, as yet neither perturbative high-energy calculations nor low-energy non-perturbative techniques have been successfully extended to the mixture of high energy and low transverse momenta which characterize traditional ''soft'' diffractive processes. The simplest soft diffractive process is elastic scattering. In this case it is easiest to accept that there is an exchanged ''pomeron'', which can be pictured as a virtual entity with no electric charge or strong charge (colour), perhaps like an excitation of the vacuum. The same pomeron is expected to appear in all diffractive processes. Understanding the pomeron in QCD is a fundamental theoretical and experimental challenge. In the last two or three years the ''frontier'' in this challenging area of QCD has been pushed back significantly in both theory and experiment. Progress has been achieved by studying the evolution of hard collisions to relatively smaller constituent momenta (small x) and by studying ''hard'' diffractive collisions containing simultaneous signatures of diffraction and hard perturbative processes. The hard processes have included high transverse momentum jet production, deep inelastic lepton scattering, and (most recently) W

"Work smart, wear your hard hat"

CERN Multimedia

2003-01-01

Falling objects and collisions are frequent occurrences in work sites and hazardous areas. Hard hats can help prevent many types of accident and can even save lives. Just imagine an 800 g spanner falling from a 13 m high scaffold onto the head of someone standing below - a nightmare scenario! The impact to the head is equivalent to that of a 5 kg weight falling from 2 metres. That is just what happened to Gerd Fetchenhauer when he was working on the UA1 experiment. Fortunately, he was wearing a hard hat at the time. "That hat saved my life," he explains. "It punched a hole right through the hat and I was a bit dazed for a couple of hours but otherwise I was OK." Since that day, Gerd Fetchenhauer, now working on CMS, is never seen on a work site without his hard hat on. Work sites have proliferated at CERN with the construction of the LHC and its detectors, and the wearing of hard hats is compulsory (not to mention life-saving). In the underground caverns and experiment halls, where gantry cranes and other h...

Cobalt allergy in hard metal workers

Energy Technology Data Exchange (ETDEWEB)

Fischer, T; Rystedt, I

1983-03-01

Hard metal contains about 10% cobalt. 853 hard metal workers were examined and patch tested with substances from their environment. Initial patch tests with 1% cobalt chloride showed 62 positive reactions. By means of secondary serial dilution tests, allergic reactions to cobalt were reproduced in 9 men and 30 women. Weak reactions could not normally be reproduced. A history of hand eczema was found in 36 of the 39 individuals with reproducible positive test reactions to cobalt, while 21 of 23 with a positive initial patch test but negative serial dilution test had never had any skin problems. Hand etching and hand grinding, mainly female activities and traumatic to the hands, were found to involve the greatest risk of cobalt sensitization. 24 individuals had an isolated cobalt allergy. They had probably been sensitized by hard metal work, while the individuals, all women, who had simultaneous nickel allergy had probably been sensitized to nickel before their employment and then became sensitized to cobalt by hard metal work. A traumatic occupation, which causes irritant contact dermatitis and/or a previous contact allergy or atopy is probably a prerequisite for the development of cobalt allergy.

Hard gap in epitaxial semiconductor-superconductor nanowires

DEFF Research Database (Denmark)

Chang, W.; Albrecht, S. M.; Jespersen, T. S.

2015-01-01

a continuum of subgap states---a situation that nullifies topological protection. Here, we report a hard superconducting gap induced by proximity effect in a semiconductor, using epitaxial Al-InAs superconductor-semiconductor nanowires. The hard gap, along with favorable material properties and gate...

Chromium carbide-CNT nanocomposites with enhanced mechanical properties

International Nuclear Information System (INIS)

Singh, Virendra; Diaz, Rene; Balani, Kantesh; Agarwal, Arvind; Seal, Sudipta

2009-01-01

Chromium carbide is widely used as a tribological coating material in high-temperature applications requiring high wear resistance and hardness. Herein, an attempt has been made to further enhance the mechanical and wear properties of chromium carbide coatings by reinforcing carbon nanotubes (CNTs) as a potential replacement of soft binder matrix using plasma spraying. The microstructures of the sprayed CNT-reinforced Cr 3 C 2 coatings were characterized using transmission electron microscopy and scanning electron microscopy. The mechanical properties were assessed using micro-Vickers hardness, nanoindentation and wear measurements. CNT reinforcement improved the hardness of the coating by 40% and decreased the wear rate of the coating by almost 45-50%. Cr 3 C 2 reinforced with 2 wt.% CNT had an elastic modulus 304.5 ± 29.2 GPa, hardness of 1175 ± 60 VH 0.300 and a coefficient of friction of 0.654. It was concluded that the CNT reinforcement increased the wear resistance by forming intersplat bridges while the improvement in the hardness was attributed to the deformation resistance of CNTs under indentation

The wear and corrosion resistance of shot peened-nitrided 316L austenitic stainless steel

International Nuclear Information System (INIS)

Hashemi, B.; Rezaee Yazdi, M.; Azar, V.

2011-01-01

Research highlights: → Shot peening-nitriding increased the wear resistance and surface hardness of samples. → This treatment improved the surface mechanical properties. → Shot peening alleviates the adverse effects of nitriding on the corrosion behavior. -- Abstract: 316L austenitic stainless steel was gas nitrided at 570 o C with pre-shot peening. Shot peening and nitriding are surface treatments that enhance the mechanical properties of surface layers by inducing compressive residual stresses and formation of hard phases, respectively. The structural phases, micro-hardness, wear behavior and corrosion resistance of specimens were investigated by X-ray diffraction, Vickers micro-hardness, wear testing, scanning electron microscopy and cyclic polarization tests. The effects of shot peening on the nitride layer formation and corrosion resistance of specimens were studied. The results showed that shot peening enhanced the nitride layer formation. The shot peened-nitrided specimens had higher wear resistance and hardness than other specimens. On the other hand, although nitriding deteriorated the corrosion resistance of the specimens, cyclic polarization tests showed that shot peening before the nitriding treatment could alleviate this adverse effect.

Hard Distraction and Deep Inelastic Scattering

International Nuclear Information System (INIS)

BJORKEN, J.D.

1994-01-01

Since the advent of hard-collision physics, the study of diffractive processes- 'shadow physics' - has been less prominent than before. However, there is now a renewed interest in the subject, especially in that aspect which synthesizes the short-distance, hard-collision phenomena with the classical physics of large rapidity-gaps. This is especially stimulated by the recent data on deep-inelastic scattering from HERA, as well as the theoretical work which relates to it. The word 'diffraction' is sometimes used by high-energy physicists in a loose way. So I here begin by defining what I mean by the term: A diffractive process occurs if and only if there is a large rapidity gap in the produced-particle phase space which is not exponentially suppressed. Here a rapidity gap means essentially no hadrons produced into the rapidity gap (which operates in the 'lego' phase-space of pseudo-rapidity and azimuthal angle). And non-exponential suppression implies that the cross-section for creating a gap with width Δη does not have a power-law decrease with increasing sub energy Δη, but behaves at most like some power of pseudorapidity Δη∼ logs. The term 'hard diffraction' shall simply refer to those diffractive processes which have jets in the final-state phase-space. We may also distinguish, if desired, two subclasses, as suggested by Ingelman i) Diffractive hard processes have jets on only one side of the rapidity gap. ii) Hard diffractive processes have jets on both sides of the rapidity gap

Wave packet autocorrelation functions for quantum hard-disk and hard-sphere billiards in the high-energy, diffraction regime.

Science.gov (United States)

Goussev, Arseni; Dorfman, J R

2006-07-01

We consider the time evolution of a wave packet representing a quantum particle moving in a geometrically open billiard that consists of a number of fixed hard-disk or hard-sphere scatterers. Using the technique of multiple collision expansions we provide a first-principle analytical calculation of the time-dependent autocorrelation function for the wave packet in the high-energy diffraction regime, in which the particle's de Broglie wavelength, while being small compared to the size of the scatterers, is large enough to prevent the formation of geometric shadow over distances of the order of the particle's free flight path. The hard-disk or hard-sphere scattering system must be sufficiently dilute in order for this high-energy diffraction regime to be achievable. Apart from the overall exponential decay, the autocorrelation function exhibits a generally complicated sequence of relatively strong peaks corresponding to partial revivals of the wave packet. Both the exponential decay (or escape) rate and the revival peak structure are predominantly determined by the underlying classical dynamics. A relation between the escape rate, and the Lyapunov exponents and Kolmogorov-Sinai entropy of the counterpart classical system, previously known for hard-disk billiards, is strengthened by generalization to three spatial dimensions. The results of the quantum mechanical calculation of the time-dependent autocorrelation function agree with predictions of the semiclassical periodic orbit theory.

Water Hardness Level and ItAND#8217;s Health Effects

Directory of Open Access Journals (Sweden)

Necmettin Kocak

2011-04-01

Full Text Available Water hardness is a term used to define the number of ions contained in the water, especially quantity sulphate, carbonate salts of calcium and magnesium. This characteristis of water is a important quality in it’s use as drinking water, industrial water and service water. The temporary hardness level of water cames from bicarbonate salts of calcium and magnesium whereas chloride, sulphate, nitrate, phosphate, silicate salts of calcium and magnesium. In order to indicate the hardness level of water samples French Hardness Level is used in our country. There is a larger amounth of calcium and magnesium salts in hard water samples. These minerals have very important functions in the human body. In this study, the importance of hard water in terms of human health has been assessed under light of current information. The studies about the preventive role of hard water in cardiovascular diseases, cerebrovascular diseases, stroke and many types of cancer areviewed. These studies Express that higher levels of calcium and magnesium hard water provide a higher reduction in these disease. Water, which must be consumed as 2 liters per dayis very important for human life. Hard water contains a lot of the minerals that must be taker daily, especially calcium and magnesium. It’s advised that water for consumption to have medium hardness. The hardness level of water is an aesthetic quality. Thus, in populations having a taste for soft water, the effort of individuals to softer the network water provided by municipalities using different equipments, in addition to their preference of soft water in plastic or glass bottles for consumption could imply lack of benefit of hard water for population health and also bring out some risks in terms of water hygiene. [TAF Prev Med Bull 2011; 10(2.000: 187-192

Transport coefficients and mechanical response in hard-disk colloidal suspensions

Science.gov (United States)

Zhang, Bo-Kai; Li, Jian; Chen, Kang; Tian, Wen-De; Ma, Yu-Qiang

2016-11-01

We investigate the transport properties and mechanical response of glassy hard disks using nonlinear Langevin equation theory. We derive expressions for the elastic shear modulus and viscosity in two dimensions on the basis of thermal-activated barrier-hopping dynamics and mechanically accelerated motion. Dense hard disks exhibit phenomena such as softening elasticity, shear-thinning of viscosity, and yielding upon deformation, which are qualitatively similar to dense hard-sphere colloidal suspensions in three dimensions. These phenomena can be ascribed to stress-induced “landscape tilting”. Quantitative comparisons of these phenomena between hard disks and hard spheres are presented. Interestingly, we find that the density dependence of yield stress in hard disks is much more significant than in hard spheres. Our work provides a foundation for further generalizing the nonlinear Langevin equation theory to address slow dynamics and rheological behavior in binary or polydisperse mixtures of hard or soft disks. Project supported by the National Basic Research Program of China (Grant No. 2012CB821500) and the National Natural Science Foundation of China (Grant Nos. 21374073 and, 21574096).

Driven self-assembly of hard nanoplates on soft elastic shells

International Nuclear Information System (INIS)

Zhang Yao-Yang; Hua Yun-Feng; Deng Zhen-Yu

2015-01-01

The driven self-assembly behaviors of hard nanoplates on soft elastic shells are investigated by using molecular dynamics (MD) simulation method, and the driven self-assembly structures of adsorbed hard nanoplates depend on the shape of hard nanoplates and the bending energy of soft elastic shells. Three main structures for adsorbed hard nanoplates, including the ordered aggregation structures of hard nanoplates for elastic shells with a moderate bending energy, the collapsed structures for elastic shells with a low bending energy, and the disordered aggregation structures for hard shells, are observed. The self-assembly process of adsorbed hard nanoplates is driven by the surface tension of the elastic shell, and the shape of driven self-assembly structures is determined on the basis of the minimization of the second moment of mass distribution. Meanwhile, the deformations of elastic shells can be controlled by the number of adsorbed rods as well as the length of adsorbed rods. This investigation can help us understand the complexity of the driven self-assembly of hard nanoplates on elastic shells. (paper)

Hard template synthesis of metal nanowires

Directory of Open Access Journals (Sweden)

Go eKawamura

2014-11-01

Full Text Available Metal nanowires (NWs have attracted much attention because of their high electron conductivity, optical transmittance and tunable magnetic properties. Metal NWs have been synthesized using soft templates such as surface stabilizing molecules and polymers, and hard templates such as anodic aluminum oxide, mesoporous oxide, carbon nanotubes. NWs prepared from hard templates are composites of metals and the oxide/carbon matrix. Thus, selecting appropriate elements can simplify the production of composite devices. The resulting NWs are immobilized and spatially arranged, as dictated by the ordered porous structure of the template. This avoids the NWs from aggregating, which is common for NWs prepared with soft templates in solution. Herein, the hard template synthesis of metal NWs is reviewed, and the resulting structures, properties and potential applications are discussed.

Broad-band hard X-ray reflectors

DEFF Research Database (Denmark)

Joensen, K.D.; Gorenstein, P.; Hoghoj, P.

1997-01-01

Interest in optics for hard X-ray broad-band application is growing. In this paper, we compare the hard X-ray (20-100 keV) reflectivity obtained with an energy-dispersive reflectometer, of a standard commercial gold thin-film with that of a 600 bilayer W/Si X-ray supermirror. The reflectivity...... of the multilayer is found to agree extraordinarily well with theory (assuming an interface roughness of 4.5 Angstrom), while the agreement for the gold film is less, The overall performance of the supermirror is superior to that of gold, extending the band of reflection at least a factor of 2.8 beyond...... that of the gold, Various other design options are discussed, and we conclude that continued interest in the X-ray supermirror for broad-band hard X-ray applications is warranted....

Rock-hard coatings

NARCIS (Netherlands)

Muller, M.

2007-01-01

Aircraft jet engines have to be able to withstand infernal conditions. Extreme heat and bitter cold tax coatings to the limit. Materials expert Dr Ir. Wim Sloof fits atoms together to develop rock-hard coatings. The latest invention in this field is known as ceramic matrix composites. Sloof has

Tensile testing study of dynamic interactions between dislocations and precipitate in vanadium alloys

International Nuclear Information System (INIS)

Tougou, Kouichi; Nogiwa, Kimihiro; Tachikawa, Kazuhiro; Fukumoto, Ken-ichi

2013-01-01

To investigate the hardening of fine Ti(OCN) precipitate, we performed in situ transmission electron microscopy (TEM) observations during tensile testing of dislocations gliding through fine Ti(OCN) precipitates in thermally aged V–4Cr–4Ti alloys. The obstacle strength parameter was estimated from the critical bow-out angle, ϕ, of the dislocation lines from the microstructural change during tensile deformation observed in the TEM images. From image processing analysis of the dislocation motion, the value of the obstacle strength parameter of Ti(OCN) precipitates of 4-nm size was determined to be 0.30. The increase in yield stress calculated from the measured dislocation behavior pinned around precipitates was Δσ in situ = 43 MPa, and the increase in yield stress measured by the micro-Vickers hardness test was Δσ HV = 49.5 MPa. Data from in situ TEM observations during tensile testing and from micro-Vickers hardness tests were in good agreement; thus, the obstacle strength parameter of the Ti(OCN) precipitates of 4-nm size was successfully obtained experimentally. The obstacle strength parameter also was compared with data from a previous study, and there was also quite good agreement. Therefore, the obstacle strength parameter obtained from this study is measurable and is a reliable measure of mechanical property changes following precipitation in V–4Cr–4Ti alloys

Spark-plasma sintering and mechanical property of mechanically alloyed NiAl powder compact and ball-milled (Ni+Al) mixed powder compact

International Nuclear Information System (INIS)

Kim, J.S.; Jang, Y.I.; Kwon, Y.S.; Kim, Y.D.; Ahn, I.S.

2001-01-01

Mechanically-alloyed NiAl powder and (Ni+Al) powder mixture prepared by ball-milling were sintered by spark-plasma sintering (SPS) process. Densification behavior and mechanical property were determined from the experimental results and analysis such as changes in linear shrinkage, shrinkage rate, microstructure, and phase during sintering process, Vicker's hardness and transverse rupture strength tests. Densification mechanisms for MA-NiAl powder compact and (Ni+Al) powder mixture were different from each other. While the former showed a rapid increase in densification rate only at higher temperature region of 800-900 o C, the latter revealed firstly a rapid increase in densification rate even at low temperature of 300 o C and a subsequent increase up to 500 o C. Densities of both powder compact (MA and mixture) sintered at 1150 o C for 5 min were 98 and above 99 %, respectively. Sintered bodies were composed mainly of NiAl phase with Ni 3 Al as secondary phase for both powders. Sintered body of MA-NiAl powder showed a very fine grain structure. Crystallite size determined by XRD result and the Sherrer's equation was approximately 80 nm. Vicker's hardness for the sintered bodies of (Ni+Al) powder mixture and MA-NiAl powder were 410±12 H v and 555±10 H v , respectively, whereas TRS values 1097±48 MPa and 1393±75 MPa. (author)

Strain-softening behavior of an Fe-6.5 wt%Si alloy during warm deformation and its applications

International Nuclear Information System (INIS)

Fu Huadong; Zhang Zhihao; Yang Qiang; Xie Jianxin

2011-01-01

Research highlights: → An Fe-6.5 wt%Si alloy exhibits strain-softening behavior after large deformation. → The decrease of the order degree is responsible for the strain-softening behavior. → The strain-softening behavior of Fe-6.5 wt%Si alloy can be applied in cold rolling. → An Fe-6.5 wt%Si thin strip with thickness of 0.20 mm is fabricated by cold rolling. - Abstract: An Fe-6.5 wt%Si alloy with columnar grains was compressed at a temperature below its recrystallization temperature. The Vickers hardness and structure of the alloy before and after deformation were investigated. The results showed that with an increase in the degree of deformation, Vickers hardness of the alloy initially increased rapidly and then decreased slowly, indicating that the alloy had a strain-softening behavior after a large deformation. Meanwhile, the work-hardening exponent of the alloy decreased significantly. Transmission electron microscopy confirmed that the decrease of the order degree was responsible for the strain-softening behavior of the deformed alloy. Applying its softening behavior, the Fe-6.5 wt%Si alloy with columnar grains was rolled at 400 deg. C and then at room temperature. An Fe-6.5 wt%Si thin strip with thickness of 0.20 mm was fabricated. The surface of the strip was bright and had no obvious edge cracks.

Development of a radio frequency atmospheric pressure plasma jet for diamond-like carbon coatings on stainless steel substrates

Science.gov (United States)

Sohbatzadeh, F.; Samadi, O.; Siadati, S. N.; Etaati, G. R.; Asadi, E.; Safari, R.

2016-10-01

In this paper, an atmospheric pressure plasma jet with capacitively coupled radio frequency discharge was developed for diamond-like carbon (DLC) coatings on stainless steel substrates. The plasma jet was generated by argon-methane mixture and its physical parameters were investigated. Relation between the plasma jet length and width of the powered electrode was discussed. Optical and electrical characteristics were studied by optical emission spectroscopy, voltage and current probes, respectively. The evolutions of various species like ArI, C2 and CH along the jet axis were investigated. Electron temperature and density were estimated by Boltzmann plot method and Saha-Boltzmann equation, respectively. Finally, a diamond-like carbon coating was deposited on stainless steel-304 substrates by the atmospheric pressure radio frequency plasma jet in ambient air. Raman spectroscopy, scanning electron microscopy (SEM), atomic force microscopy and Vickers hardness test were used to study the deposited films. The length of the jet was increased by increasing the width of the powered electrode. The estimated electron temperature and density were 1.43 eV and 1.39 × 1015 cm-3, respectively. Averaged Vicker's hardness of the coated sample was three times greater than that of the substrate. The SEM images of the deposited thin films revealed a 4.5 μm DLC coated for 20 min.

Elemental, microstructural, and mechanical characterization of high gold orthodontic brackets after intraoral aging.

Science.gov (United States)

Hersche, Sepp; Sifakakis, Iosif; Zinelis, Spiros; Eliades, Theodore

2017-02-01

The purpose of the present study was to investigate the elemental composition, the microstructure, and the selected mechanical properties of high gold orthodontic brackets after intraoral aging. Thirty Incognito™ (3M Unitek, Bad Essen, Germany) lingual brackets were studied, 15 brackets as received (control group) and 15 brackets retrieved from different patients after orthodontic treatment. The surface of the wing area was examined by scanning electron microscopy (SEM). Backscattered electron imaging (BEI) was performed, and the elemental composition was determined by X-ray EDS analysis (EDX). After appropriate metallographic preparation, the mechanical properties tested were Martens hardness (HM), indentation modulus (EIT), elastic index (ηIT), and Vickers hardness (HV). These properties were determined employing instrumented indentation testing (IIT) with a Vickers indenter. The results were statistically analyzed by unpaired t-test (α=0.05). There were no statistically significant differences evidenced in surface morphology and elemental content between the control and the experimental group. These two groups of brackets showed no statistically significant difference in surface morphology. Moreover, the mean values of HM, EIT, ηIT, and HV did not reach statistical significance between the groups (p>0.05). Under the limitations of this study, it may be concluded that the surface elemental content and microstructure as well as the evaluated mechanical properties of the Incognito™ lingual brackets remain unaffected by intraoral aging.

Factorization and non-factorization in diffractive hard scattering

International Nuclear Information System (INIS)

Berera, Arjun

1997-01-01

Factorization, in the sense defined for inclusive hard scattering, is discussed for diffractive hard scattering. A factorization theorem similar to its inclusive counterpart is presented for diffractive DIS. For hadron-hadron diffractive hard scattering, in contrast to its inclusive counterpart, the expected breakdown of factorization is discussed. Cross section estimates are given from a simple field theory model for non-factorizing double-pomeron-exchange (DPE) dijet production with and without account for Sudakov suppression

Hard template synthesis of metal nanowires

OpenAIRE

Kawamura, Go; Muto, Hiroyuki; Matsuda, Atsunori

2014-01-01

Metal nanowires (NWs) have attracted much attention because of their high electron conductivity, optical transmittance, and tunable magnetic properties. Metal NWs have been synthesized using soft templates such as surface stabilizing molecules and polymers, and hard templates such as anodic aluminum oxide, mesoporous oxide, carbon nanotubes. NWs prepared from hard templates are composites of metals and the oxide/carbon matrix. Thus, selecting appropriate elements can simplify the production o...

ERRATUM: Work smart, wear your hard hat

CERN Multimedia

2003-01-01

An error appeared in the article «Work smart, wear your hard hat» published in Weekly Bulletin 27/2003, page 5. The impact which pierced a hole in the hard hat worn by Gerd Fetchenhauer was the equivalent of a box weighing 5 kg and not 50 kg.

Flour quality and kernel hardness connection in winter wheat

Directory of Open Access Journals (Sweden)

Szabó B. P.

2016-12-01

Full Text Available Kernel hardness is controlled by friabilin protein and it depends on the relation between protein matrix and starch granules. Friabilin is present in high concentration in soft grain varieties and in low concentration in hard grain varieties. The high gluten, hard wheat our generally contains about 12.0–13.0% crude protein under Mid-European conditions. The relationship between wheat protein content and kernel texture is usually positive and kernel texture influences the power consumption during milling. Hard-textured wheat grains require more grinding energy than soft-textured grains.

Hardness of Clustering

Indian Academy of Sciences (India)

First page Back Continue Last page Overview Graphics. Hardness of Clustering. Both k-means and k-medians intractable (when n and d are both inputs even for k =2). The best known deterministic algorithms. are based on Voronoi partitioning that. takes about time. Need for approximation – “close” to optimal.

Evaluation of hard fossil fuel

International Nuclear Information System (INIS)

Zivkovic, S.; Nuic, J.

1999-01-01

Because of its inexhaustible supplies hard fossil fuel will represent the pillar of the power systems of the 21st century. Only high-calorie fossil fuels have the market value and participate in the world trade. Low-calorie fossil fuels ((brown coal and lignite) are fuels spent on the spot and their value is indirectly expressed through manufactured kWh. For the purpose of determining the real value of a tonne of low-calorie coal, the criteria that help in establishing the value of a tonne of hard coal have to be corrected and thus evaluated and assessed at the market. (author)

Calorimeter triggers for hard collisions

International Nuclear Information System (INIS)

Landshoff, P.V.; Polkinghorne, J.C.

1978-01-01

We discuss the use of a forward calorimeter to trigger on hard hadron-hadron collisions. We give a derivation in the covariant parton model of the Ochs-Stodolsky scaling law for single-hard-scattering processes, and investigate the conditions when instead a multiple- scattering mechanism might dominate. With a proton beam, this mechanism results in six transverse jets, with a total average multiplicity about twice that seen in ordinary events. We estimate that its cross section is likely to be experimentally accessible at avalues of the beam energy in the region of 100 GeV/c

Hardness of ion implanted ceramics

International Nuclear Information System (INIS)

Oliver, W.C.; McHargue, C.J.; Farlow, G.C.; White, C.W.

1985-01-01

It has been established that the wear behavior of ceramic materials can be modified through ion implantation. Studies have been done to characterize the effect of implantation on the structure and composition of ceramic surfaces. To understand how these changes affect the wear properties of the ceramic, other mechanical properties must be measured. To accomplish this, a commercially available ultra low load hardness tester has been used to characterize Al 2 O 3 with different implanted species and doses. The hardness of the base material is compared with the highly damaged crystalline state as well as the amorphous material

Hardness of enamel exposed to Coca-Cola and artificial saliva.

Science.gov (United States)

Devlin, H; Bassiouny, M A; Boston, D

2006-01-01

The purpose of this study was to determine the rate of change in indentation hardness of enamel in permanent teeth exposed to Coca-Cola. In a further experiment, the ability of a commercially available artificial saliva to remineralize enamel treated with Coca-Cola was tested. Ten enamel specimens were randomly chosen to be treated with Coca-Cola (experimental groups) and seven with water (control group). The fluids were applied for 1, 2, 3 h and overnight (15 h), washed off with a few drops of water and the moist enamel indentation hardness tested after each interval. With Coca-Cola treatment, the mean enamel hardness was 92.6% (s.d. = 7.9) of the original baseline hardness after 1 h, 93.25% (s.d. = 10.15) after 2 h, 85.7% (s.d. = 12.03) after 3 h and 80.3% after 15 h. The mean indentation hardness of control specimens treated with water was 108.7% (s.d. = 16.09) of the original hardness after 1 h, 99.09% (s.d. = 18.98) after 2 h, 98.97% (s.d. =11.24) after 3 h and 98.42% (s.d. = 22.78) after 15 h. In a separate experiment, the hardness of 9 enamel specimens was tested, as previously described, before and after treatment with Coca-Cola overnight and again after application of artificial saliva for 3 min. Coca-Cola reduced the mean indentation hardness of enamel in the teeth, but the hardness was partially restored with artificial saliva (Salivart) and increased by 18% from the demineralized enamel hardness.

Investigation of Plasma Facing Components in Plasma Focus Operation

Science.gov (United States)

Roshan, M. V.; Babazadeh, A. R.; Kiai, S. M. Sadat; Habibi, H.; Mamarzadeh, M.

2007-09-01

Both aspects of the plasma-wall interactions, counter effect of plasma and materials, have been considered in our experiments. The AEOI plasma focus, Dena, has Filippov-type electrodes. The experimental results verify that neutron production increases using tungsten as an anode insert material, compared to the copper one. The experiments show decrement of the hardness of Aluminum targets outward the sides, from 135 to 78 in Vickers scale. The sputtering yield is about 0.0065 for deuteron energy of 50 keV.

Recrystallization of deformed copper - kinetics and microstructural evolution

DEFF Research Database (Denmark)

Lin, Fengxiang

The objective of this study is to investigate the recrystallization kinetics and microstructural evolution in copper deformed to high strains, including copper deformed by cold-rolling and copper deformed by dynamic plastic deformation (DPD). Various characterization techniques were used, including...... electron backscatter diffraction (EBSD), Vickers hardness test, 3D X-ray diffraction (3DXRD) and differential scanning calorimetry (DSC). For the cold-rolled samples, a series of initial parameters was investigated for their effects on the recrystallization kinetics and textures, including initial grain...

Improvement of microstructure and mechanical properties of high dense SiC ceramics manufactured by high-speed hot pressing

International Nuclear Information System (INIS)

Voyevodin, V.; Sayenko, S.; Lobach, K.; Tarasov, R.; Zykova, A.; Svitlychnyi, Ye.; Surkov, A.; Abelentsev, V.; Ghaemi, H.; Szkodo, M.; Gajowiec, G.; Kmiec, M.; Antoszkiewicz, M.

2017-01-01

Non-oxide ceramics possess high physical-mechanical properties, corrosion and radiation resistance, which can be used as a protective materials for radioactive wastes disposal. The aim of the present study was the manufacturing of high density SiC ceramics with advanced physical and mechanical parameters. The high performance on the properties of produced ceramics was determined by the dense and monolithic structure. The densified silicon carbide samples possessed good mechanical strength, with a high Vickers micro hardness up to 28.5 GPa.

Mechanical properties of Mo and TZM alloy neutron-irradiated at high temperatures

International Nuclear Information System (INIS)

Ueda, Kazukiyo; Satou, Manabu; Hasegawa, Akira; Abe, Katsunori

1997-01-01

This work reports the mechanical properties of irradiated molybdenum (Mo) and its alloy, TZM. Recrystallized and stress-relieved specimens were irradiated at five temperatures between 373 and 800degC in FFTF/MOTA to fluence levels of 6.8 to 34 dpa. Irradiation embrittlement and hardening were evaluated by three-point bend test and Vickers hardness test, respectively. Stress-relieved materials showed the enough ductility even after high fluence irradiation. The role of layered structure of stress-relieved specimen was discussed. (author)

Tribological properties of ion-implanted steels

International Nuclear Information System (INIS)

Iwaki, Masaya

1987-01-01

The tribological properties such as surface hardness, friction and wear have been studied for low carbon steels and tool steels implanted with many types of ion including metallic elements. The hardness measured by Vickers or Knoop hardness testers as a function of normal load is dependent on the implanted species, fluence and substrate. The friction coefficients measured by Bowden-Leben type of friction tests or detected during wear tests also depend on the implantation conditions. The improvement in the wear resistance, which is most important for industrial use of implanted materials, has been investigated for AISI H13 prehardened and tool steels implanted with nitrogen and boron ions. The relationship between hardness, friction and wear is discussed in comparison with the microcharacteristics such as composition and chemical bonding states measured by means of secondary ion mass spectrometry and X-ray photoelectron spectroscopy. It is concluded that the increase in hardness and/or the decrease in friction coefficient play(s) an important role in improving the wear resistance, and the relationship between relative wear volume and relative hardness is correlated for boron and nitrogen implantation. (orig.)

Hard probes 2006 Asilomar

CERN Multimedia

2006-01-01

"The second international conference on hard and electromagnetic probes of high-energy nuclear collisions was held June 9 to 16, 2006 at the Asilomar Conference grounds in Pacific Grove, California" (photo and 1/2 page)

Experimental study of microstructure, mechanical and tribological properties of cBN particulates SS316 alloy based MMCs fabricated by DMLS technique

Energy Technology Data Exchange (ETDEWEB)

Hussain, M.; Mandal, V.; Singh, P. K.; Kumar, P.; Kumar, V.; Das, A. K. [Indian Institute of Technology (ISM), Dhanbad (India)

2017-06-15

Direct metal laser sintering process (DMLS) was chosen to develop cBN particulates reinforced SS316 based Metal matrix composite (MMC) with 5 %, 7.5 % and 10 % cBN in the nitrogen gas atmosphere using continuous wave fibre laser of 400 W output capacity. Effects of process parameters such as laser power, beam scanning speed and the mixing ratio of powder on different physical properties of the developed MMC were investigated. It was found that the physical and mechanical properties such as friction and wear behavior, micro hardness and density come up with improved results. FESEM images indicate the microstructure of the composite and evidently confirms the presence of cubic boron nitride in the SS316 matrix where chromium nitride acted as a binder in the presence of nitrogen atmosphere. The Vickers hardness values of the developed MMCs with laser power 60 W and 65 W were found in the range of 276-478 HV{sub 0}.2 and 297-460 HV{sub 0}.2, respectively. It was found that Vickers hardness is directly proportional to the % of cBN in the powder mixture and the laser beam power. The wear resistance of the sintered MMCs increased with increasing cBN content in powder mixture and re- sults show that wear of MMCs are much lower than that of SS316. X-Ray diffraction (XRD) analysis of the fabricated MMC confirms the presence of different phases such as cBN, CrN, CrB{sub 2}, Cr{sub 2}N and Fe{sub 3}N as a consequence of a series of chemical reaction between cBN and different elements of SS316 in nitrogen atmosphere.

Experimental study of microstructure, mechanical and tribological properties of cBN particulates SS316 alloy based MMCs fabricated by DMLS technique

International Nuclear Information System (INIS)

Hussain, M.; Mandal, V.; Singh, P. K.; Kumar, P.; Kumar, V.; Das, A. K.

2017-01-01

Direct metal laser sintering process (DMLS) was chosen to develop cBN particulates reinforced SS316 based Metal matrix composite (MMC) with 5 %, 7.5 % and 10 % cBN in the nitrogen gas atmosphere using continuous wave fibre laser of 400 W output capacity. Effects of process parameters such as laser power, beam scanning speed and the mixing ratio of powder on different physical properties of the developed MMC were investigated. It was found that the physical and mechanical properties such as friction and wear behavior, micro hardness and density come up with improved results. FESEM images indicate the microstructure of the composite and evidently confirms the presence of cubic boron nitride in the SS316 matrix where chromium nitride acted as a binder in the presence of nitrogen atmosphere. The Vickers hardness values of the developed MMCs with laser power 60 W and 65 W were found in the range of 276-478 HV_0.2 and 297-460 HV_0.2, respectively. It was found that Vickers hardness is directly proportional to the % of cBN in the powder mixture and the laser beam power. The wear resistance of the sintered MMCs increased with increasing cBN content in powder mixture and re- sults show that wear of MMCs are much lower than that of SS316. X-Ray diffraction (XRD) analysis of the fabricated MMC confirms the presence of different phases such as cBN, CrN, CrB_2, Cr_2N and Fe_3N as a consequence of a series of chemical reaction between cBN and different elements of SS316 in nitrogen atmosphere.

Analysis of surface hardness of artificially aged resin composites

Directory of Open Access Journals (Sweden)

Denise Cremonezzi Tornavoi

2012-02-01

Full Text Available This study evaluated the effect of artificially accelerated aging (AAA on the surface hardness of eight composite resins: Filtek Z250, Filtek Supreme, 4 Seasons, Herculite, P60, Tetric Ceram, Charisma, and Filtek Z100. Sixteen specimens were made from the test piece of each material, using an 8.0 × 2.0 mm teflon matrix. After 24 hours, eight specimens from each material were submitted to three surface hardness readings using a Shimadzu Microhardness Tester for 5 seconds at a load of 50 gf. The other eight specimens remained in the artificially accelerated aging machine for 382 hours and were submitted to the same surface hardness analysis. The means of each test specimen were submitted to the Kolmogorov-Smirnov test (p > 0.05, ANOVA and Tukey test (p < 0.05. With regard to hardness (F = 86.74, p < 0.0001 the analysis showed significant differences among the resin composite brands. But aging did not influence the hardness of any of the resin composites (F = 0.39, p = 0.53. In this study, there was interaction between the resin composite brand and the aging factors (F = 4.51, p < 0.0002. It was concluded that notwithstanding the type of resin, AAA did not influence surface hardness. However, with regard to hardness there was a significant difference among the resin brands.

Soft is hard and hard is easy: learning technologies and social media

Directory of Open Access Journals (Sweden)

Jon Dron

2013-03-01

Full Text Available Questo articolo riguarda principalmente la natura delle tecnologie per apprendere, con una particolare attenzione ai social media. Muovendo dalla definizione fornita da W. Brian Arthur delle tecnologie come un insieme di fenomeni orchestrati per un qualche uso, l’articolo amplia la teoria di Arthur ridefinendo e allargando la distinzione comunemente accettata tra tecnologie soft e hard, laddove le tecnologie soft sono intese come quelle che richiedono l’orchestrazione di fenomeni da parte degli esseri umani, mentre le tecnologie hard sono quelle per le quali l’orchestrazione è predeterminata o incorporata. Le tecnologie per apprendere sono quelle in cui le pedagogie (anch’esse tecnologie sono parte dell’insieme. Le conseguenze di questa prospettiva vengono esplorate nel quadro di diversi modelli pedagogici e in relazione agli approcci basati sul social learning in una varietà di contesti, dai corsi per corrispondenza ai MOOC.

Dependence of Hardness of Silicate Glasses on Composition and Thermal History

DEFF Research Database (Denmark)

Jensen, Martin; Smedskjær, Morten Mattrup; Yue, Yuanzheng

composition on hardness of silicate glasses. E-glasses of different compositions are subjected to various degrees of annealing to obtain various fictive temperatures in the glasses. It is found that hardness decreases with the fictive temperature. Addition of Na2O to a SiO2-Al2O3-Na2O glass system causes......The prediction of hardness is possible for crystalline materials, but so far not possible for glasses. In this work, several important factors that should be used for predicting the hardness of glasses are discussed. To do so, we have studied the influences of thermal history and chemical...... a decrease in hardness. However, hardness cannot solely be determined from the degree of polymerisation of the glass network. It is also determined by the effect of ionic radius on hardness. However, this effect has opposite trend for alkali and alkaline earth ions. The hardness increases with ionic radius...

Effects of multiple firings on the microstructure of zirconia and veneering ceramics.

Science.gov (United States)

Alkurt, Murat; Yeşil Duymus, Zeynep; Gundogdu, Mustafa

2016-01-01

The aim of study was to evaluate the effects of multiple firings on the microstructures of zirconia and two ceramics. Vita VM9 (VMZ) and Cerabien ZR (C-Z) ceramics on a zirconia framework and zirconia without veneering ceramic (WO-Z) were evaluated. Firing methods included firing two, five, and ten times (n=10). The effects of multiple firings on the surface hardness of the materials were evaluated using a Vickers hardness (HV) tester. Data were analyzed by two-way ANOVA and Tukey's test (α=0.05). After firing five and ten times, the hardness of VM-Z and C-Z increased significantly (p0.05). In the XRD analysis, zirconia had similar tetragonal (t)-monoclinic (m) phase transformations of Y-TZP after the different firing times. Clinically, multiple firings did not affect the microstructure of zirconia, but the structures of the two ceramics were affected.

Identification of a novel FAM83H mutation and microhardness of an affected molar in autosomal dominant hypocalcified amelogenesis imperfecta.

Science.gov (United States)

Hyun, H-K; Lee, S-K; Lee, K-E; Kang, H-Y; Kim, E-J; Choung, P-H; Kim, J-W

2009-11-01

To determine the underlying molecular genetic aetiology of a family with the hypocalcified form of amelogenesis imperfecta and to investigate the hardness of the enamel and dentine of a known FAM83H mutation. Mutational screening of the FAM83H on the basis of candidate gene approach was performed. All exons and exon-intron boundaries was amplified and sequenced. A microhardness test was performed to measure the Vickers microhardness value. A novel nonsense mutation (c.1354C>T, p.Q452X) was identified in the last exon of FAM83H, which resulted in soft, uncalcified enamel. The affected enamel was extremely soft (about 17% of the normal control), but the underlying dentine was as hard as the normal control. Mutational analysis revealed a novel mutation in FAM83H gene. Hardness of dentine was not affected by the mutation, whilst the enamel was extremely soft.

Playing Moderately Hard to Get

Directory of Open Access Journals (Sweden)

Stephen Reysen

2013-12-01

Full Text Available In two studies, we examined the effect of different degrees of attraction reciprocation on ratings of attraction toward a potential romantic partner. Undergraduate college student participants imagined a potential romantic partner who reciprocated a low (reciprocating attraction one day a week, moderate (reciprocating attraction three days a week, high (reciprocating attraction five days a week, or unspecified degree of attraction (no mention of reciprocation. Participants then rated their degree of attraction toward the potential partner. The results of Study 1 provided only partial support for Brehm’s emotion intensity theory. However, after revising the high reciprocation condition vignette in Study 2, supporting Brehm’s emotion intensity theory, results show that a potential partners’ display of reciprocation of attraction acted as a deterrent to participants’ intensity of experienced attraction to the potential partner. The results support the notion that playing moderately hard to get elicits more intense feelings of attraction from potential suitors than playing too easy or too hard to get. Discussion of previous research examining playing hard to get is also re-examined through an emotion intensity theory theoretical lens.

Crystal growth, structure, defects, mechanical and spectral properties of Nd{sub 0.01}:Gd{sub 0.89}La{sub 0.1}NbO{sub 4} mixed crystal

Energy Technology Data Exchange (ETDEWEB)

Ding, Shoujun; Lu, Wancheng; Xu, Jinrui [Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, Anhui Province (China); University of Science and Technology of China, Hefei (China); Zhang, Qingli; Luo, Jianqiao; Liu, Wenpeng; Sun, Guihua; Sun, Dunlu [Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, Anhui Province (China)

2017-10-15

A novel mixed laser crystal of Nd:GdLaNbO{sub 4} (Nd:GLNO) was grown successfully by conventional Czochralski method. The unit cell parameters were obtained by Rietveld refinement method. The density of the as-grown crystal was measured by Archimedean buoyancy method and calculated in theory. Absorption spectrum of Nd:GLNO crystal was recorded at room temperature, and 11 absorption peaks were assigned. The defects of Nd:GLNO crystal were revealed by using chemical etching method with phosphoric acid as etchant. The mechanical properties (including hardness, yield strength, elastic stiffness constant, fracture toughness and brittleness index) were systemically estimated based on Vickers hardness test. All these obtained results play a quite important role in further investigation of Nd:GLNO crystal. (orig.)

Mechanical and Corrosion Properties of Magnesium-Bioceramic Nanocomposites

Directory of Open Access Journals (Sweden)

Kowalski K.

2016-09-01

Full Text Available Magnesium alloys have recently attracted much attention as a new generation of biodegradable metallic materials. In this work, Mg1Mn1Zn0.3Zr-bioceramic nanocomposites and their scaffolds were synthesized using a combination of mechanical alloying and a space-holder sintering process. The phase and microstructure analysis was carried out using X-ray diffraction, scanning electron microscopy and the properties were measured using hardness and corrosion testing equipment. Nanostructured Mg-bioceramic composites with a grain sizes below 73 nm were synthesized. The Vickers hardnesses for the bulk nanostructured Mg-based composites are two times greater than that of pure microcrystalline Mg metal (50 HV0.3. Produced Mg-based bionanomaterials can be applied in medicine.

Mechanical properties of CO2/MIG welded structural rolled steel and stainless steel

International Nuclear Information System (INIS)

Lim, Jong Young; Yoon, Myong Jin; Kim, Sang Youn; Kim, Tae Gyu; Shin, Hyeon Seung

2015-01-01

To accomplish long-term use of specific parts of steel, welding technology is widely applied. In this study, to compare the efficiency in improving mechanical properties, rolled steel (SS400) was welded with stainless steel (STS304) by both CO 2 welding method and MIG (metal inert gas) welding method, respectively. Multi-tests were conducted on the welded specimen, such as X-ray irradiation, Vickers' Hardness, tensile test, fatigue test and fatigue crack growth test. Based on the fatigue crack growth test performed by two different methods, the relationship of da/dN was analyzed. Although the hardness by the two methods was similar, tensile test and fatigue properties of MIG welded specimen are superior to CO 2 welded one.

Structural and electrical properties of copper-nickel-aluminum alloys obtained by conventional powder metallurgy method

International Nuclear Information System (INIS)

Monteiro, Waldemar A.; Carrio, Juan A.G.; Silveira, C.R. da; Pertile, H.K.S.

2009-01-01

This work looked for to search out systematically, in scale of laboratory, copper-nickel-aluminum alloys (Cu-Ni-Al) with conventional powder metallurgy processing, in view of the maintenance of the electric and mechanical properties with the intention of getting electric connectors of high performance or high mechanical damping. After cold uniaxial pressing (1000 kPa), sintering (780 deg C) and convenient homogenization treatments (500 deg C for different times) under vacuum (powder metallurgy), the obtained Cu-Ni-Al alloys were characterized by optical microscopy, electrical conductivity, Vickers hardness. X rays powder diffraction data were collected for the sintered samples in order to a structural and microstructural analysis. The comparative analysis is based on the sintered density, hardness, macrostructures and microstructures of the samples. (author)

RESEARCH OF FATIGUE AND MECHANICAL PROPERTIES AlMg1SiCu ALUMINIUM ALLOYS

Directory of Open Access Journals (Sweden)

Mária Mihaliková

2015-11-01

Full Text Available The paper is concerned with an analysis of utility and fatigue properties of industrially produced aluminium alloy, specifically EN AW 6061 (AlMg1SiCu, reinforced with the particles of SiC. The following properties were subject to evaluation: microstructure and sub-structure, mechanical characteristics. All of these mechanical properties in pre- and post- equal channel angular pressed (ECAP state have been studied. The hardness was evaluated by Vickers hardness test at the load of HV10. The significant part the thesis was devoted to the fatigue properties at cyclic load in torsion. The presented results demonstrate well that the combination of fractography and microscopy can give a significant contribution to the knowledge of initiation and propagation crack in the aluminium alloy.

Obtention of high hardness multilayer systems by laser ablation

International Nuclear Information System (INIS)

Mejia T, I.S.

2007-01-01

In this thesis work the synthesis of thin films of titanium nitride (TiN), amorphous carbon nitride (CN x ) amorphous carbon (a-C) and Ti/TiN/CNx multilayers and Ti/TiN/a-C by means of the laser ablation technique, with the objective of obtaining films of high hardness is studied, as well as to produce multilayer coatings with superior properties to the individual layers. The effect that has the laser fluence used for ablationing the targets in the structure and mechanical properties of the films deposited of TiN was investigated. It was found that the hardness is increased in lineal way approximately with the fluence increment up to 19 J/cm 2 . Thin films of a-C with hardness of the order of 12 GPa. likewise CN x films with high hardness (18.4 GPa) were obtained. The hardness of the deposited films was analyzed and it was related with its microstructure and deposit conditions. It was concluded that the Ti/TiN/CNx and Ti/TiN/a-C systems presented bigger hardness that of its individual components. (Author)

Sampling from a polytope and hard-disk Monte Carlo

International Nuclear Information System (INIS)

Kapfer, Sebastian C; Krauth, Werner

2013-01-01

The hard-disk problem, the statics and the dynamics of equal two-dimensional hard spheres in a periodic box, has had a profound influence on statistical and computational physics. Markov-chain Monte Carlo and molecular dynamics were first discussed for this model. Here we reformulate hard-disk Monte Carlo algorithms in terms of another classic problem, namely the sampling from a polytope. Local Markov-chain Monte Carlo, as proposed by Metropolis et al. in 1953, appears as a sequence of random walks in high-dimensional polytopes, while the moves of the more powerful event-chain algorithm correspond to molecular dynamics evolution. We determine the convergence properties of Monte Carlo methods in a special invariant polytope associated with hard-disk configurations, and the implications for convergence of hard-disk sampling. Finally, we discuss parallelization strategies for event-chain Monte Carlo and present results for a multicore implementation

The over-the-limb hard X-ray events

Science.gov (United States)

Hudson, H. S.

Over-the-limb hard X-ray events offer a uniquely direct view of the hard X-ray emission from the solar corona during a major flare. Limb occultation at angles greater than about 10 deg (an arbitrary definition of this class of events) excludes any confusion with brighter chromospheric sources. Published observations of seven over-the-limb events, beginning with the prototype flare of March 30, 1969, are reviewed. The hard X-ray spectra appear to fall into two classes: hard events, with power-law index of about 2.0; and soft events, with power-law index about 5.4. This tendency towards bimodality is only significant at the 90-percent confidence level due to the smallness of the number of events observed to date. If borne out by future data, the bimodality would suggest the existence of two different acceleration mechanisms.

Constraint satisfaction problems with isolated solutions are hard

International Nuclear Information System (INIS)

Zdeborová, Lenka; Mézard, Marc

2008-01-01

We study the phase diagram and the algorithmic hardness of the random 'locked' constraint satisfaction problems, and compare them to the commonly studied 'non-locked' problems like satisfiability of Boolean formulae or graph coloring. The special property of the locked problems is that clusters of solutions are isolated points. This simplifies significantly the determination of the phase diagram, which makes the locked problems particularly appealing from the mathematical point of view. On the other hand, we show empirically that the clustered phase of these problems is extremely hard from the algorithmic point of view: the best known algorithms all fail to find solutions. Our results suggest that the easy/hard transition (for currently known algorithms) in the locked problems coincides with the clustering transition. These should thus be regarded as new benchmarks of really hard constraint satisfaction problems

Excavation Technology for Hard Rock - Problems and Prospects

International Nuclear Information System (INIS)

Gillani, S.T.A.; Butt, N.

2009-01-01

Civil engineering projects have greatly benefited from the mechanical excavation of hard rock technology. Mining industry, on the other hand, is still searching for major breakthroughs to mechanize and then automate the winning of ore and drivage of access tunnels in its metalliferous sector. The aim of this study is to extend the scope of drag bits for road headers in hard rock cutting. Various factors that can impose limitations on the potential applications of drag bits in hard rock mining are investigated and discussed along with alternative technology options. (author)

Performance ratio hardness characteristics polystyrene-metal composite materials

International Nuclear Information System (INIS)

Klepikov, V.F.; Prokhorenko, E.M.; Lytvynenko, V.V.; Zakharchenko, A.A.; Hazhmuradov, M.A.

2015-01-01

The methods of measuring the hardness of layered polystyrene-metallic composite materials. It is proposed to use powder-like tungsten and powder-like steel as radiation-protective layer. A measurement of the hardness of composites of different composition, and given its dependence on the particle size and their form. The possibility of increasing the hardness of the composites reinforced with metallic additives. Radiation-protective characteristics were calculated for the studied species of composite materials. Influence of the quantitative composition of the metal components is studied on the change of the absorbed dose of gamma radiation

3D Bioprinting Technologies for Hard Tissue and Organ Engineering

Science.gov (United States)

Wang, Xiaohong; Ao, Qiang; Tian, Xiaohong; Fan, Jun; Wei, Yujun; Hou, Weijian; Tong, Hao; Bai, Shuling

2016-01-01

Hard tissues and organs, including the bones, teeth and cartilage, are the most extensively exploited and rapidly developed areas in regenerative medicine field. One prominent character of hard tissues and organs is that their extracellular matrices mineralize to withstand weight and pressure. Over the last two decades, a wide variety of 3D printing technologies have been adapted to hard tissue and organ engineering. These 3D printing technologies have been defined as 3D bioprinting. Especially for hard organ regeneration, a series of new theories, strategies and protocols have been proposed. Some of the technologies have been applied in medical therapies with some successes. Each of the technologies has pros and cons in hard tissue and organ engineering. In this review, we summarize the advantages and disadvantages of the historical available innovative 3D bioprinting technologies for used as special tools for hard tissue and organ engineering. PMID:28773924

3D Bioprinting Technologies for Hard Tissue and Organ Engineering

Directory of Open Access Journals (Sweden)

Xiaohong Wang

2016-09-01

Full Text Available Hard tissues and organs, including the bones, teeth and cartilage, are the most extensively exploited and rapidly developed areas in regenerative medicine field. One prominent character of hard tissues and organs is that their extracellular matrices mineralize to withstand weight and pressure. Over the last two decades, a wide variety of 3D printing technologies have been adapted to hard tissue and organ engineering. These 3D printing technologies have been defined as 3D bioprinting. Especially for hard organ regeneration, a series of new theories, strategies and protocols have been proposed. Some of the technologies have been applied in medical therapies with some successes. Each of the technologies has pros and cons in hard tissue and organ engineering. In this review, we summarize the advantages and disadvantages of the historical available innovative 3D bioprinting technologies for used as special tools for hard tissue and organ engineering.

3D Bioprinting Technologies for Hard Tissue and Organ Engineering.

Science.gov (United States)

Wang, Xiaohong; Ao, Qiang; Tian, Xiaohong; Fan, Jun; Wei, Yujun; Hou, Weijian; Tong, Hao; Bai, Shuling

2016-09-27

Hard tissues and organs, including the bones, teeth and cartilage, are the most extensively exploited and rapidly developed areas in regenerative medicine field. One prominent character of hard tissues and organs is that their extracellular matrices mineralize to withstand weight and pressure. Over the last two decades, a wide variety of 3D printing technologies have been adapted to hard tissue and organ engineering. These 3D printing technologies have been defined as 3D bioprinting. Especially for hard organ regeneration, a series of new theories, strategies and protocols have been proposed. Some of the technologies have been applied in medical therapies with some successes. Each of the technologies has pros and cons in hard tissue and organ engineering. In this review, we summarize the advantages and disadvantages of the historical available innovative 3D bioprinting technologies for used as special tools for hard tissue and organ engineering.

Unified Research on Network-Based Hard/Soft Information Fusion

Science.gov (United States)

2016-02-02

3.2.1 Hard +Soft Data Association Data gathered during various Counterinsurgency (or COIN) operations is in different formats . For example, the...characteristic, observation time, and related data. Figure 45: Sample snapshot frame from hard sensor data TML formats were developed and...160 Figure 54: Penn State components of overall hard and soft fusion process Summary of Year 1 Accomplishments • Team formation • Initial

Hard scattering and gauge/string duality

International Nuclear Information System (INIS)

Polchinski, Joseph; Strassler, Matthew J.

2002-01-01

We consider high-energy fixed-angle scattering of glueballs in confining gauge theories that have supergravity duals. Although the effective description is in terms of the scattering of strings, we find that the amplitudes are hard (power law). This is a consequence of the warped geometry of the dual theory, which has the effect that in an inertial frame the string process is never in the soft regime. At small angle we find hard and Regge behaviors in different kinematic regions

Radiation hardness of undoped BGO crystals

International Nuclear Information System (INIS)

Sahu, S.K.; Peng, K.C.; Huang, H.C.; Wang, C.H.; Chang, Y.H.; Hou, W.S.; Ueno, K.; Chou, F.I.; Wei, Y.Y.

1997-01-01

We measured the radiation hardness of undoped BGO crystals from two different manufacturers. Such crystals are proposed to be used in a small-angle calorimeter of the BELLE detector of the KEK B-factory. Transparency and scintillation light output of the crystals were monitored to see the effect of radiation damage. The crystals show considerable radiation hardness up to 10.2 Mrad equivalent dose, which is much higher than the maximum expected dosage of 500 krad per year of running at BELLE. (orig.)

Diffusion corrections to the hard pomeron

CERN Document Server

Ciafaloni, Marcello; Müller, A H; Ciafaloni, Marcello; Taiuti, Martina

2001-01-01

The high-energy behaviour of two-scale hard processes is investigated in the framework of small-x models with running coupling, having the Airy diffusion model as prototype. We show that, in some intermediate high-energy regime, the perturbative hard Pomeron exponent determines the energy dependence, and we prove that diffusion corrections have the form hinted at before in particular cases. We also discuss the breakdown of such regime at very large energies, and the onset of the non-perturbative Pomeron behaviour.

Particle production at large transverse momentum and hard collision models

International Nuclear Information System (INIS)

Ranft, G.; Ranft, J.

1977-04-01

The majority of the presently available experimental data is consistent with hard scattering models. Therefore the hard scattering model seems to be well established. There is good evidence for jets in large transverse momentum reactions as predicted by these models. The overall picture is however not yet well enough understood. We mention only the empirical hard scattering cross section introduced in most of the models, the lack of a deep theoretical understanding of the interplay between quark confinement and jet production, and the fact that we are not yet able to discriminate conclusively between the many proposed hard scattering models. The status of different hard collision models discussed in this paper is summarized. (author)

Hard-Boiled for Hard Times in Leonardo Padura Fuentes's Detective Fiction

Science.gov (United States)

Song, H. Rosi

2009-01-01

Focusing on Leonardo Padura Fuentes's hard-boiled fiction, this essay traces the origin and evolution of the genre in Cuba. Padura Fuentes has challenged the officially sanctioned socialist "literatura policial" that became popular in the 1970s and 1980s. creating a new model of criticism that is not afraid to confront the island's socio-economic…

Extraordinarily soft, medium-hard and hard Indian wheat varieties: Composition, protein profile, dough and baking properties.

Science.gov (United States)

Katyal, Mehak; Singh, Narpinder; Virdi, Amardeep Singh; Kaur, Amritpal; Chopra, Nidhi; Ahlawat, Arvind Kumar; Singh, Anju Mahendru

2017-10-01

Hard wheat (HW), medium-hard wheat (MHW) and extraordinarily soft wheat (Ex-SW) varieties with grain hardness index (GHI) of 83 to 95, 72 to 80, 17 to 29 were evaluated for pasting, protein molecular weight (MW) distribution, dough rheology and baking properties. Flours from varieties with higher GHI had more protein content, ash content and paste viscosities. Ex-SW had more glutenins proportion as compared to HW and MHW. Flours from Ex-SW varieties showed lower NaSRC, WA and mixographic parameters as compared to HW and MHW. Dough from flours milled from Ex-SW had higher Intermolecular-β-sheets (IM-β-sheets) than those from MHW and HW. Muffins volume increased with decrease in GHI, Ex-SW varieties had more muffin volume and less air space. The accumulation of polypeptides (PPs) varied significantly in different varieties. Ex-SW variety (QBP12-10) showed accumulation of 98, 90, 81 and 79kDa PPs, which was unique and was different from other varieties. Copyright © 2017 Elsevier Ltd. All rights reserved.

Rock-hard coatings