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Haidoo Kim - One of the best experts on this subject based on the ideXlab platform.
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sintered reaction bonded Silicon nitrides with high thermal conductivity the effect of the starting si powder and si3n4 diluents
Journal of The European Ceramic Society, 2014Co-Authors: Youngjo Park, Mijung Park, Jinmyung Kim, Jaewook Lee, Haidoo KimAbstract:Abstract Silicon nitride ceramics with high thermal conductivity were fabricated by employing the reaction bonding method. It was revealed that the addition of Si 3 N 4 diluents affected both the nitriding reaction and the post-sintering behavior by changing the size of the Silicon Particle during the milling process. The reduced size of Silicon Particle led to an increased degree of nitridation. Further, narrower pore channels in the nitrided bodies caused by the reduced size of Silicon Particle enhanced the final density, by promoting the easier elimination of finer pores during post-sintering. The positive effect of the finer Silicon Particle was confirmed by a back-up experiment employing a variety of Silicon Particle sizes, produced by milling the raw Silicon powder for different milling times. Thermal conductivity was dominated by material density rather than variation of the microstructure or oxygen content in the current research.
K. Narayan Prabhu - One of the best experts on this subject based on the ideXlab platform.
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Thermal Analysis of Cerium-Treated Chill-Cast Al-23 Si Alloy
Journal of Materials Engineering and Performance, 2018Co-Authors: V. Vijeesh, K. Narayan PrabhuAbstract:The influence of elemental cerium addition on the cooling curve parameters and microstructure of hypereutectic Al-23Si alloy was investigated in this work. The cooling rate of the treated and untreated alloy samples was varied by solidifying the melt against chills of different materials in a stainless-steel tube. The cooling curve was recorded and nucleation temperatures of various phases in the alloy were measured. The results show that the chilling improves the effectiveness of the modifier. The two main phases of the alloy, primary Silicon and eutectic Silicon, were nucleated at temperatures of about 661.2 and 571.6 °C, respectively. The addition of Ce to slowly cooled alloys resulted in an increase in undercooling temperature of both the phases, with a decrease in its nucleation temperature, whereas the same additions increased the nucleation temperatures in chilled alloys. Based on the thermal analysis results, a relation between thermal analysis parameter ( $$\Delta T_{G}$$ Δ T G ) and Silicon Particle size of the alloy was proposed.
Jianmin Qu - One of the best experts on this subject based on the ideXlab platform.
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interface reaction controlled diffusion in binary solids with applications to lithiation of Silicon in lithium ion batteries
Journal of The Mechanics and Physics of Solids, 2013Co-Authors: Jianmin QuAbstract:Abstract Solid state diffusion in a binary system, such as lithiation into crystalline Silicon, often involves two symbiotic processes, namely, interfacial chemical reaction and bulk diffusion. Building upon our earlier work ( Cui et al., 2012b , J. Mech. Phys. Solids, 60 (7), 1280–1295), we develop a mathematical framework in this study to investigate the interaction between bulk diffusion and interfacial chemical reaction in binary systems. The new model accounts for finite deformation kinematics and stress–diffusion interaction. It is applicable to arbitrary shape of the phase interface. As an example, the model is used to study the lithiation of a spherical Silicon Particle. It is found that a dimensionless parameter β = k f e V m B R 0 / D 0 plays a significant role in determining the kinetics of the lithiation process. This parameter, analogous to the Biot number in heat transfer, represents the ratio of the rate of interfacial chemical reaction and the rate of bulk diffusion. Smaller β means slower interfacial reaction, which would result in higher and more uniform concentration of lithium in the lithiated region. Furthermore, for a given β , the lithiation process is always controlled by the interfacial chemical reaction initially, until sufficient Silicon has been lithiated so that the diffusion distance for lithium reaches a threshold value, beyond which bulk diffusion becomes the slower process and controls the overall lithiation kinetics.
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a finite deformation stress dependent chemical potential and its applications to lithium ion batteries
Journal of The Mechanics and Physics of Solids, 2012Co-Authors: Jianmin QuAbstract:This paper reports the development of a new stress-dependent chemical potential for solid state diffusion under multiple driving forces including mechanical stresses. The new stress-dependent chemical potential accounts for nonlinear, inelastic, and finite deformation. By using this stress-dependent chemical potential, insertion and extraction of lithium ions into a Silicon Particle is investigated. The distribution and evolution of diffusion-induced stress during the insertion/extraction processes are numerically calculated. Critical Particle size is obtained as a function of the charging/discharging rates. It is also found that when plastic deformation occurs, the hoop stresses on the Particle surface, contrary to intuition, can become positive even during the charging process, which may explain some of the recent experimental observations.
Youngjo Park - One of the best experts on this subject based on the ideXlab platform.
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sintered reaction bonded Silicon nitrides with high thermal conductivity the effect of the starting si powder and si3n4 diluents
Journal of The European Ceramic Society, 2014Co-Authors: Youngjo Park, Mijung Park, Jinmyung Kim, Jaewook Lee, Haidoo KimAbstract:Abstract Silicon nitride ceramics with high thermal conductivity were fabricated by employing the reaction bonding method. It was revealed that the addition of Si 3 N 4 diluents affected both the nitriding reaction and the post-sintering behavior by changing the size of the Silicon Particle during the milling process. The reduced size of Silicon Particle led to an increased degree of nitridation. Further, narrower pore channels in the nitrided bodies caused by the reduced size of Silicon Particle enhanced the final density, by promoting the easier elimination of finer pores during post-sintering. The positive effect of the finer Silicon Particle was confirmed by a back-up experiment employing a variety of Silicon Particle sizes, produced by milling the raw Silicon powder for different milling times. Thermal conductivity was dominated by material density rather than variation of the microstructure or oxygen content in the current research.
V. Vijeesh - One of the best experts on this subject based on the ideXlab platform.
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Thermal Analysis of Cerium-Treated Chill-Cast Al-23 Si Alloy
Journal of Materials Engineering and Performance, 2018Co-Authors: V. Vijeesh, K. Narayan PrabhuAbstract:The influence of elemental cerium addition on the cooling curve parameters and microstructure of hypereutectic Al-23Si alloy was investigated in this work. The cooling rate of the treated and untreated alloy samples was varied by solidifying the melt against chills of different materials in a stainless-steel tube. The cooling curve was recorded and nucleation temperatures of various phases in the alloy were measured. The results show that the chilling improves the effectiveness of the modifier. The two main phases of the alloy, primary Silicon and eutectic Silicon, were nucleated at temperatures of about 661.2 and 571.6 °C, respectively. The addition of Ce to slowly cooled alloys resulted in an increase in undercooling temperature of both the phases, with a decrease in its nucleation temperature, whereas the same additions increased the nucleation temperatures in chilled alloys. Based on the thermal analysis results, a relation between thermal analysis parameter ( $$\Delta T_{G}$$ Δ T G ) and Silicon Particle size of the alloy was proposed.