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101.
Anoop K. Mukhopadhyay Keshaw D. Joshi Arjun Dey Riya Chakraborty Ashok K. Mandal Amit Rav Jiten Ghosh Sandip Bysakh Sampad K. Biswas Satish C. Gupta 《Ceramics International》2011,37(7):2365-2376
Shock recovered samples of a coarse grain (10 μm), high density (>99.9% theoretical) alumina from asymmetric impact tests conducted at 6.5 GPa (e.g. 3.2 times its Hugoniot Elastic Limit) in a single stage gas gun and characterized by X-ray diffractometry, scanning and field emission scanning electron microscopy, and transmission electron microscopy showed prolific presence of reduced crystallite size, higher average microstrain, grain localized micro/nano-scale deformations, micro-cleavages, grain-boundary microcracks, micro-wing crack formation, extensive shear induced deformations and fractures localized at grains, grain boundaries and triple grain junctions, grain localized entanglement of dislocations and their pile up impeded at grain boundaries. A new qualitative model based on micro-shear and micro-twist induced deformation and fracture in single and/or multiple planes in suitably oriented grain and/or grain assembly was developed to explain the experimentally observed damage evolution process. 相似文献
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Hem Joshi Bryan R. Moser Shailesh N. Shah Anurag Mandalika Terry Walker 《European Journal of Lipid Science and Technology》2010,112(7):802-809
The low temperature operability and oxidative stability of cottonseed oil methyl esters (CSME) were improved with four anti‐gel additives as well as one antioxidant additive, gossypol. Low temperature operability and oxidative stability of CSME was determined by cloud point (CP), pour point (PP), cold filter plugging point (CFPP), and oxidative stability index (OSI). The most significant reductions in CP, PP, and CFPP in all cases were obtained with Technol®, with the average reduction in temperature found to be 3.9 °C. Gunk®, Heet®, and Howe's® were progressively less effective, as indicated by average reductions in temperature of 3.4, 3.0, and 2.8 °C, respectively. In all cases, the magnitude of CFPP reduction was greater than for PP and especially CP. Addition of gossypol, a polyphenolic aldehyde, resulted in linear improvement in OSI (R2 = 0.9804). The OSI of CSME increased from 5.0 to 8.3 h with gossypol at a concentration of 1000 ppm. 相似文献
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107.
B. Joshi S. S. Islam H. S. Mavi Vinita Kumari T. Islam A. K. Shukla Harsh 《Bulletin of Materials Science》2009,32(1):31-35
The laser induced etching of semi-insulating GaAs 〈100〉 is carried out to create porous structure under super- and sub-bandgap
photon illumination (h v). The etching mechanism is different for these separate illuminations where defect states play the key role in making distinction
between these two processes. Separate models are proposed for both the cases to explain the etching efficiency. It is observed
that under sub-bandgap photon illumination the etching process starts vigorously through the mediation of intermediate defect
states. The defect states initiate the pits formation and subsequently pore propagation occurs due to asymmetric electric
field in the pore. Formation of GaAs nanostructures is observed using scanning electron (SEM) and atomic force microscopy
(AFM). 相似文献
108.
G. Sharma K.B. Joshi M.S. Dhaka M.C. Mishra R.K. Kothari B.K. Sharma 《Intermetallics》2011,19(8):1107-1114
The electronic structure of three intermetallic alloys namely Ti3Al, TiAl and TiAl3 in terms of Compton profiles is reported in this work. Directional Compton profiles are calculated for all the three alloys employing CRYSTAL code within the framework of density functional theory. The spherically averaged theoretical values are compared with the measurements made using 59.54 keV gamma-rays from Am241 source. The calculations are in overall agreement with measurements in all cases. The measurements are also compared with the superposition of LCAO profiles of elemental solids. For Ti3Al and TiAl3 the LCAO values show better agreement whereas for TiAl the synthesized LCAO values are closer to the experiment. Effect of titanium 3d electrons is clearly visible in intermediate range of momentum in the Ti rich alloy. Charge transfer in the three alloys has also been estimated following the superposition of experimental profiles of Ti and Al metals. Comparison of Compton spectra of Ti3Al, TiAl and TiAl3 with the superposition of the Compton spectra of elemental constituents suggests a charge transfer of 2.8, 0.9 and 0.6 electron per Al atom, respectively. Such large values seem unreasonable and, therefore, this approach cannot be used for any reliable determination of the charge transfer in this system. 相似文献
109.
Siow Ling Ho Shailendra P. Joshi Andrew A. O. Tay 《International Journal of Fracture》2014,187(2):227-238
Bimaterial interfaces in microelectronics packages are the most common regions of failure under thermo-mechanical excursions. In this work, we report experimentally observed role of heating rate on the delamination initiation and propagation across a metal-polymer interface in a microelectronic package. We observe that the rate of delamination propagation increases with increasing heating rate. When the heating rate increases, in addition to the higher amount of delamination growth per unit time, experimental results suggests that higher growth will also incur per unit temperature (loading). Correspondingly, the temperature at which complete delamination occur decreases. Using finite element modeling with cohesive interfaces, we provide a plausible explanation to this observed phenomenon. The analyses indicate that the mechanical behavior of the bimaterial interface is sensitive to both temperature and thermal rate. 相似文献
110.
Siva P. Gurrum Yogendra K. Joshi Jungho Kim 《Numerical Heat Transfer, Part A: Applications》2013,63(8):777-790
A feasibility study for using metallic solid-liquid phase change materials (PCMs) in periodic power dissipating devices is reported. Thermal enhancement has been studied with PCM enclosed inside microchannels within semiconductor devices. Benchmarking experiments were performed with PCM inside copper microchannels and compared with numerical predictions. PCMs perform well at lower power levels for silicon carbide semiconductor devices, but the use of high thermal conductivity spreaders such as diamond becomes mandatory at the higher power levels projected in future applications. PCM effectiveness and temperature reductions as a function of chip thickness, channel width, and power dissipated are presented. Temperature reductions up to 25°C can be realized with a combination of diamond spreaders and PCM filled microchannels. 相似文献