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  • Wynn Hanna posted an update 5 days, 8 hours ago

    According to the fractography of the tensile-fractured surfaces undertaken using optical and scanning electron microscopy, fractures of the iron-bearing phases were found to be the source of cracking in alloys with high Si content. In the case of those with low Si content (≤3 mass%), cracks were believed to have been caused by the debonding of iron-bearing phases from the aluminum matrix.We present a comparison between the thermal sensing behaviors of 4H-SiC Schottky barrier diodes, junction barrier Schottky diodes, and PiN diodes in a temperature range from 293 K to 573 K. The thermal sensitivity of the devices was calculated from the slope of the forward voltage versus temperature plot. At a forward current of 10 μA, the PiN diode presented the highest sensitivity peak (4.11 mV K-1), compared to the peaks of the junction barrier Schottky diode and the Schottky barrier diode (2.1 mV K-1 and 1.9 mV K-1, respectively). The minimum temperature errors of the PiN and junction barrier Schottky diodes were 0.365 K and 0.565 K, respectively, for a forward current of 80 μA±10 μA. The corresponding value for the Schottky barrier diode was 0.985 K for a forward current of 150 μA±10 μA. In contrast to Schottky diodes, the PiN diode presents a lower increase in saturation current with temperature. Therefore, the nonlinear contribution of the saturation current with respect to the forward current is negligible; this contributes to the higher sensitivity of the PiN diode, allowing for the design and fabrication of highly linear sensors that can operate in a wider temperature range than the other two diode types.In this study, glass-ceramic was prepared by adding TiO₂ as a nucleating agent to induce the internal crystallization behavior of diopside (CaO-MgO-2SiO₂)-based glass. The optimum composition for producing a transparent glass-ceramic was a composition of 15 wt% of TiO₂ mixed with 85% diopside. The light transmittance of the specimen decreased as the heat treatment temperature increased. When 394 nm excitation light was incident on the glass-ceramic containing 0.05% Eu₂O₃, red light of 614 nm wavelength emitted. We examined the relationship between the light emission mechanism and the crystal structure of the diopside-based glass-ceramic. We also discussed the applicability of the specimens prepared in this study as light emitting materials in various fields.The workability of Al-xMg alloys with a high Mg content (Al-6Mg, Al-8Mg, Al-9Mg) was evaluated by investigating the microstructure and processing map. Hot torsion tests were conducted in the range of 350-500 °C between 0.1 and 1 s-1. Constitutive equations were derived from various effective stress-strain curves, and the thermal activation energies for deformation obtained were 171 kJ/mol at Al-6Mg, 195 kJ/mol at Al-8Mg, and 220 kJ/mol at Al-9Mg. In the case of the processing map, the instability region, which widened with increasing Mg content, was due mainly to the influence of the Mg solute, which activated grain boundary cracking and flow localization.The effect of addition of Mischmetal (MM) on the microstructure, electrical and thermal conductivity, and mechanical properties of the as-extruded Al-MM based alloys were investigated. The studied AlxMM alloys (where x = 0.2, 0.5, 1.0, 1.5, 2.0 and 5.0 wt.%) were cast and homogenized at 550 °C for 4 h. The cast billets were extruded into 12 mm bars with an extrusion ratio of 39 at 550 °C. selleck chemicals llc The addition of MM resulted in the formation of Al11(Ce, La)₃ intermetallic compounds and the area fraction of these intermetallic compounds increased with an increase in the MM content. The Al11(Ce, La)₃ phase, which was distributed in the as-cast alloys, was crushed into fine particles and arrayed along the extruded direction during the extrusion process. In particular, these intermetallic compounds in the extruded Al-5.0MM alloy were distributed with a wide-band structure due to the fragmentation of the eutectic phase with a lamellar structure. As the MM content increased from 1.0 wt.% to 5.0 wt.%, the average grain size decreased remarkably from 740 to 73 μm. This was due to formation of Al11(Ce, La)₃ particles during the hot extrusion process, which promoted dynamic recrystallization and suppression of grain growth. The electrical and thermal conductivity of the extruded alloys containing up to 2.0 wt.% MM were around 60.5% IACS and 230 W/m · K, respectively. However, the electrical and thermal conductivity of the extruded alloy with 5.0 wt.% MM decreased to 55.4% IACS and 206 W/m · K, respectively. As the MM content increased from 1.0 wt.% to 5.0 wt.%, the ultimate tensile strength (UTS) was improved remarkably from 74 to 119 MPa which was attributed to the grain refinement and formation of Al11(Ce, La)₃ intermetallic compounds by the addition of MM.Figure of merit the product of piezoelectric charge constant and the piezoelectric voltage constant-d33 × g33 in piezoelectric energy harvesting systems are critical measures in energy harvester applications. It is difficult to achieve high figure of merit because of the interdependence of d33 and the relative dielectric constant, εr. Until now, the prohibitive amount of effort required to solve this problem has led to it being considered an unsolvable issue. Lead zirconate titanate ceramic, Pb(Zr,Ti)O₃, has been reported to exhibit high values of d33 and εr. However, to be employed as piezoelectric energy harvester, a candidate material is required to exhibit both high piezoelectric charge coefficient and high piezoelectric electric voltage coefficient simultaneously. To enhance the figure of merit of Pb(Zr,Ti)O₃-based materials, dopants have also been considered. Pb(Zn,Ni,Nb)O₃- added Pb(Zr,Ti)O₃, Pb(Zr,Ti)O₃-Pb(Zn,Ni,Nb)O₃ ceramic has been reported to exhibit a high d33 value of 561 pC/N. It’s dielectric constant has also been reported to be low at 1898. In this study, Pb(Zr,Ti)O₃-Pb(Zn,Ni,Nb)O₃-Pb(In,Nb)O₃ was investigated in the context of enhancing the figure of merit of Pb(Zr,Ti)O₃-based materials. During the proposed process, we increased the corresponding figure of merit by adding Pb(In,Nb)O₃ material. Besides exhibiting a low dielectric constant, the Pb(In,Nb)O₃ material was also observed to exhibit high d33 × g33 as the proposed doping increased the value of d33 greatly, while maintaining the dielectric constant (Yan, J., et al., 2019. Large engancement of trans coefficient in PZT-PZN energy harvesting system through introducing low εrPIN relaxor. Journal of the European Ceramic Society, 39, pp.2666-2672). Further, we conducted an optimization experiment by controlling the doping concentration and the sintering temperature.

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