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Hardness Measurements (hardness + measurement)
Selected AbstractsInfluence of Ti on the Mechanical Properties of AgCuInTi Active Brazing Fillers,ADVANCED ENGINEERING MATERIALS, Issue 1-2 2009Matteo Galli Active brazing fillers were produced by adding Ti to a AgCuIn alloy and used to fabricate ceramic-metal joints. The alloy was investigated by hardness measurements and microscopy analyses and the joints tested in bending. The results show that Ti has a hardening effect. However, for the considered values of Ti addition (0.5,1.5 wt %), the extent of the hardening is insignificantly influenced by the Ti introduced in the filler. [source] Fatigue crack initiation life estimation in a steel welded joint by the use of a two-scale damage modelFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 5 2009N. LAUTROU ABSTRACT This work deals with the fatigue behaviour of S355NL steel welded joints classically used in naval structures. The approach suggested here, in order to estimate the fatigue crack initiation life, can be split into two stages. First, stabilized stress,strain cycles are obtained in all points of the welded joint by a finite element analysis, taking constant or variable amplitude loadings into account. This calculation takes account of: base metal elastic,plastic behaviour, variable yield stress based on hardness measurements in various zones of the weld, local geometry at the weld toe and residual stresses if any. Second, if a fast elastic shakedown occurs, a two-scale damage model based on Lemaitre et al.'s work is used as a post-processor in order to estimate the fatigue crack initiation life. Material parameters for this model were identified from two Wöhler curves established for base metal. As a validation, four-point bending fatigue tests were carried out on welded specimens supplied by ,DCNS company'. Two load ratios were considered: 0.1 and 0.3. Residual stress measurements by X-ray diffraction completed this analysis. Comparisons between experimental and calculated fatigue lives are promising for the considered loadings. An exploitation of this method is planned for another welding process. [source] Effects of ultraviolet irradiation on the static and dynamic properties of neoprene rubbersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Hsoung-Wei Chou Abstract Rubbers deteriorate when they are exposed to ultraviolet irradiation for long periods of time. By conducting a series of hardness measurements and simple tension tests, the static properties of neoprene rubbers before and after exposure to various durations of ultraviolet irradiation were first measured. It is found that the Shore A hardness and tensile modulus of neoprene rubbers after exposure to ultraviolet irradiation are increased but their elongation at break, tensile strength, and energy to break are significantly decreased. On the basis of a complex spring model of a vibration system, the dynamic shear properties of neoprene rubbers before and after exposure to different durations of ultraviolet irradiation were then determined from the experimental results of dynamic transmissibility tests. It is also found that the storage modulus, loss modulus, and loss factor of neoprene rubbers are drastically affected by the duration of ultraviolet irradiation they experienced. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] The effect of disinfectant solutions on the hardness of acrylic resin denture teethJOURNAL OF ORAL REHABILITATION, Issue 7 2003A. C. Pavarina summary, This investigation studied the effects of disinfectant solutions on the hardness of acrylic resin denture teeth. The occlusal surfaces of 64 resin denture teeth were ground flat with abrasives up to 400-grit silicon carbide paper. Measurements were made after polishing and after the specimens were stored in water at 37 °C for 48 h. The specimens were then divided into four groups and immersed in chemical disinfectants (4% chlorhexidine; 1% sodium hypochlorite and sodium perborate) for 10 min. The disinfection methods were performed twice to simulate clinical conditions and hardness measurements were made. Specimens tested as controls were immersed in water during the same disinfection time. Eight specimens were produced for each group. After desinfection procedures, testing of hardness was also performed after the samples were stored at 37 °C for 7, 30, 60, 90 and 120 days. Data were analysed using two-way analysis of variance (anova) and Tukey's test at 95% confidence level. According to the results, no significant differences were found between materials and immersion solutions (P > 0·05). However, a continuous decrease in hardness was noticed after ageing (P < 0·05). It was conclude that the surfaces of both acrylic resin denture teeth softened upon immersion in water regardless the disinfecting solution. [source] Mechanical Properties of Sputter-Deposited Titanium-Silicon-Carbon FilmsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2001James E. Krzanowski The effect of SiC additions on the mechanical properties of TiC films was investigated. Ti-Si-C films with varying SiC content were deposited using dual-cathode radio-frequency magnetron sputtering. The nanoindentation hardness of these films increased with SiC content to a maximum of 20,22 GPa for films in the range of 15,30 at.% SiC. The elastic modulus was also measured, and the hardness to modulus ratio (H/E) increased with SiC content, indicating that hardness increases were due to microstructural effects. The residual stress was measured in several films, but was low in magnitude, indicating that hardness measurements were not influenced by residual stress. TEM examination of several films revealed that the SiC additions altered the film microstructure in a manner that could account for the observed hardness increases. [source] Investigations on the Photoinitiator-free Photopolymerization of Acrylates by Vibrational Spectroscopic MethodsMACROMOLECULAR SYMPOSIA, Issue 1 2005Tom Scherzer Abstract Photopolymerization of acrylates without photoinitiators was carried out by irradiation with short-wavelength UV light from excimer lamps with an emission at 222 or 172 nm. Basic investigations on the reactivity of various acrylates and on the conditions under which they can be UV-cured were performed by real-time FTIR-ATR spectroscopy. Depending on the molar extinction coefficients of a specific acrylate at the wavelength of irradiation, the absorption of the light within the coating leads to a pronounced intensity gradient which significantly influences polymerization rate and conversion. Accordingly, it limits the maximum thickness of the layer that can be cured (ranging from some hundreds of nanometres up to some micrometers). In addition to the basic studies, thin acrylate coatings were also cured on pilot scale. The actual conversion in the layer after UV irradiation was directly monitored by in-line NIR reflection spectroscopy, and the resulting coatings were characterized by FTIR spectroscopy and hardness measurements. [source] Local electrochemical properties of laser beam-welded high-strength Al,Zn,Mg,Cu alloysMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 1 2008J. Wloka Butt welds of two high-strength Al,Zn,Mg,Cu alloys with different zinc contents were welded by a laser beam welding technique. Due to the high energy density of the laser beam, the microstructural changes are confined to very thin regions. Electrochemical properties of the weld heat-affected zones are investigated by local electrochemical measurement techniques and correlated with microhardness measurements, macroscopic corrosion behaviour and metallographic sections. It turned out that microelectrochemical techniques, especially the EC-pen is a versatile and easy to handle tool for the resolution of changes in the electrochemical properties across a weld bead. It unveils modifications, which cannot be resolved by hardness measurements. By microcell measurements, local corrosion kinetics can be estimated. [source] Brief communication: Puncture and crushing resistance scores of Tana river mangabey (Cercocebus galeritus) diet itemsAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2009Julie Wieczkowski Abstract Cercocebus mangabeys are characterized by dental traits that have been interpreted as adaptations to eat hard diet items. Although there are data that mangabeys include a large proportion of fruit and especially seeds in their diets, no hardness measurements have been done on mangabeys' food items. This study measured puncture and crushing resistance of food items in the diet of the Tana River mangabey (C. galeritus). Feeding data were collected by the use of scan samples from one mangabey group from August 2000 to July 2001 and from July 2005 to June 2006. Food items were collected during the latter period only, and from the same tree in or under which mangabeys had been observed eating. A portable agricultural fruit tester was used to measure the puncture resistance of fruit and a valve spring tester was used to measure the crushing resistance of seeds. The average puncture resistance of fruit was 1.7 kg/mm2, and the average crushing resistance of seeds was 12.8 kg. There were no correlations between puncture resistance, crushing resistance, or all resistance scores and frequency contribution to the diet. Resistance scores measured in this study were within the range of hardness scores of fruit and exceeded hardness scores of seeds eaten by other hard object feeders. Although this study supports the interpretation that Cercocebus dental traits are adaptations to hard object feeding, future research should investigate other material properties of food, as well as the role hard diet items play in niche separation and as fallback foods. Am J Phys Anthropol 2009. © 2009 Wiley-Liss, Inc. [source] | ||||||||||