Bismuth telluride-based alloys are the most widely used thermoelectric(TE)materials.Despite this,zonemelted Bi_(2)Te_(3)-based alloys suffer from poor mechanical properties,and polycrystalline materials prepared by po...Bismuth telluride-based alloys are the most widely used thermoelectric(TE)materials.Despite this,zonemelted Bi_(2)Te_(3)-based alloys suffer from poor mechanical properties,and polycrystalline materials prepared by powder metallurgy often disrupt the desired texture due to their inherent anisotropic crystal structure.In this study,we achieved a synergistic integration of nanoscale structures,highly oriented texture,and intrinsic BiTe’antisite defects in P-type Bi_(0.5)Sb_(1.5)Te_(3) bulk materials by employing layered directional sintering(LDS)on melt-spinning ribbons produced in a Bi-rich environment.The transmission electron microscopy analysis revealed regions of high-density distortions within the well-aligned nanograins,which play a crucial role in reducing lattice thermal conductivity.Ab initio simulations and Boltzmann transport equation analyses reveal that the BiTe’antisite defects generate both resonance states and additional phonon scattering channels.This full-spectrum phonon scattering coupled with high carrier mobility leads to a maximum figure of merit(ZT)of 1.54 at 375 K.Additionally,the compressive strength of the material reaches 140 MPa,which is 3.5 times higher than that of zone-melted counterparts.This work offers an efficient pathway for the facile preparation of high-performance Bi_(2)Te_(3)-based thermoelectric materials.展开更多
Convection heat transfer coefficient and air pressure drop in sinter layer are important factors for the design of sinter cooling craft. Due to the lack of necessary data, the two parameters are studied by experimenta...Convection heat transfer coefficient and air pressure drop in sinter layer are important factors for the design of sinter cooling craft. Due to the lack of necessary data, the two parameters are studied by experimental method. The experimental results show that heat conduction of sinter impacts the measurement of convection heat transfer coefficient. Convection heat transfer increases with the increase of air volumetric flow rate. Sinter layer without small particles(sample I) gives higher convection heat transfer coefficient than that with small particles(sample II). Under the considered conditions, volumetric convection heat transfer coefficient is in the range of 400-1800 W/(m3·°C). Air pressure drop in sinter layer increases with the increase of normal superficial velocity, as well as with the rise of air temperature. Additionally, air pressure drop also depends on sinter particle size distribution. In considered experimental conditions, pressure drop in sinter sample II is 2-3 times that in sinter sample I, which resulted from 17% small scale particles in sinter sample II.展开更多
Alumina-magnesia dry materials are widely used in induction furnace linings, but they show different kinds of damage when melting different kinds of alloy steel. In this paper, the chemical composition, phase composit...Alumina-magnesia dry materials are widely used in induction furnace linings, but they show different kinds of damage when melting different kinds of alloy steel. In this paper, the chemical composition, phase composition, and microstructure of the post-use dry materials for the working liners melting different kinds of steel were evaluated. Furthermore, the corrosion mechanism of the steel on the furnace lining materials was comprehensively analyzed. The findings reveal a significant ability of the Mn element in the molten steel to diffuse and penetrate into the refractories. Mn oxidizes to form MnO at the steel-refractory interface, and then forms a liquid phase with Al_(2)O_(3). The Cr element is dissolved into corundum and spinel of the refractories, resulting in lattice defects and structural damage of the materials. TiO2reacts with Al_(2)O_(3) to form Al_(2)TiO_(5), which plays a crucial role in preventing crack formation and propagation. Part of Ti4+dissolves into magnesia-alumina(MA), densifying the materials. TiO2also slows down the reaction between the Cr element and refractory components, further improving the corrosion resistance of the materials.展开更多
基金financially supported by the National Natural Science Foundation of China(No.51874111).
文摘Bismuth telluride-based alloys are the most widely used thermoelectric(TE)materials.Despite this,zonemelted Bi_(2)Te_(3)-based alloys suffer from poor mechanical properties,and polycrystalline materials prepared by powder metallurgy often disrupt the desired texture due to their inherent anisotropic crystal structure.In this study,we achieved a synergistic integration of nanoscale structures,highly oriented texture,and intrinsic BiTe’antisite defects in P-type Bi_(0.5)Sb_(1.5)Te_(3) bulk materials by employing layered directional sintering(LDS)on melt-spinning ribbons produced in a Bi-rich environment.The transmission electron microscopy analysis revealed regions of high-density distortions within the well-aligned nanograins,which play a crucial role in reducing lattice thermal conductivity.Ab initio simulations and Boltzmann transport equation analyses reveal that the BiTe’antisite defects generate both resonance states and additional phonon scattering channels.This full-spectrum phonon scattering coupled with high carrier mobility leads to a maximum figure of merit(ZT)of 1.54 at 375 K.Additionally,the compressive strength of the material reaches 140 MPa,which is 3.5 times higher than that of zone-melted counterparts.This work offers an efficient pathway for the facile preparation of high-performance Bi_(2)Te_(3)-based thermoelectric materials.
基金Project(51306198)supported by the National Natural Science Foundation of China
文摘Convection heat transfer coefficient and air pressure drop in sinter layer are important factors for the design of sinter cooling craft. Due to the lack of necessary data, the two parameters are studied by experimental method. The experimental results show that heat conduction of sinter impacts the measurement of convection heat transfer coefficient. Convection heat transfer increases with the increase of air volumetric flow rate. Sinter layer without small particles(sample I) gives higher convection heat transfer coefficient than that with small particles(sample II). Under the considered conditions, volumetric convection heat transfer coefficient is in the range of 400-1800 W/(m3·°C). Air pressure drop in sinter layer increases with the increase of normal superficial velocity, as well as with the rise of air temperature. Additionally, air pressure drop also depends on sinter particle size distribution. In considered experimental conditions, pressure drop in sinter sample II is 2-3 times that in sinter sample I, which resulted from 17% small scale particles in sinter sample II.
基金the National Natural Science Foundation of China(52272022)Key Program of Natural Science Foundation of Hubei Province(2021CFA071).
文摘Alumina-magnesia dry materials are widely used in induction furnace linings, but they show different kinds of damage when melting different kinds of alloy steel. In this paper, the chemical composition, phase composition, and microstructure of the post-use dry materials for the working liners melting different kinds of steel were evaluated. Furthermore, the corrosion mechanism of the steel on the furnace lining materials was comprehensively analyzed. The findings reveal a significant ability of the Mn element in the molten steel to diffuse and penetrate into the refractories. Mn oxidizes to form MnO at the steel-refractory interface, and then forms a liquid phase with Al_(2)O_(3). The Cr element is dissolved into corundum and spinel of the refractories, resulting in lattice defects and structural damage of the materials. TiO2reacts with Al_(2)O_(3) to form Al_(2)TiO_(5), which plays a crucial role in preventing crack formation and propagation. Part of Ti4+dissolves into magnesia-alumina(MA), densifying the materials. TiO2also slows down the reaction between the Cr element and refractory components, further improving the corrosion resistance of the materials.
