热电器件的界面稳定性是决定其服役可靠性和寿命的关键因素。对于方钴矿热电器件,为了抑制高温电极与方钴矿材料之间的相互扩散,需要在两者之间加入阻挡层。本工作选用Ti_(88)Al_(12)作为阻挡层,利用一步法热压烧结制备n型Yb_(0.3)Co_4S...热电器件的界面稳定性是决定其服役可靠性和寿命的关键因素。对于方钴矿热电器件,为了抑制高温电极与方钴矿材料之间的相互扩散,需要在两者之间加入阻挡层。本工作选用Ti_(88)Al_(12)作为阻挡层,利用一步法热压烧结制备n型Yb_(0.3)Co_4Sb_(12)/Ti_(88)Al_(12)/Yb_(0.3)Co_4Sb_(12)和p型CeFe3.85Mn0.15Sb12/Ti_(88)Al_(12)/CeFe3.85Mn0.15Sb12样品,研究Ti_(88)Al_(12)阻挡层与热电材料间的界面接触电阻率及微结构在加速老化实验中的演化规律。结果表明:在相同的老化条件下,n型样品的界面接触电阻率增加速度比p型样品慢,其激活能分别为84.1 k J/mol和68.8 k J/mol。对于n型样品,由元素扩散反应生成的金属间化合物中间层的增长及最终AlCo/TiCoSb层的开裂是导致界面接触电阻率增加的主要原因;而p型热电材料与Ti_(88)Al_(12)的热膨胀系数的差异加速了p型样品中界面裂纹的产生。展开更多
In thermoelectric(TE)devices,the interfacial reliability greatly influenced devices’durability and power output.For skutterudites(SKD)devices,TE legs and electrodes are bonded together with diffusion barrier layer(DB...In thermoelectric(TE)devices,the interfacial reliability greatly influenced devices’durability and power output.For skutterudites(SKD)devices,TE legs and electrodes are bonded together with diffusion barrier layer(DBL).At elevated temperatures,DBL react with SKD matrix or electrode to generate complex interfacial microstructures,which often accompanies evolutions of the thermal,electrical and mechanical properties at the interfaces.In this work,a finite element model containing the interfacial microstructure characteristics based on the experimental results was built to analyze the interfacial stress state in the skutterudite-based TE joints.A single-layer model was applied to screen out the most important parameters of the coefficient of thermal expansion(CTE)and the modulus of DBL on the first principle stress.The multilayer model considering the interfacial microstructures evolution was built to quantitively simulate the stress state of the TE joints at different aging temperatures and time.The simulation results show that the reactive CoSb2 layer is the weakest layer in both SKD/Nb and SKD/Zr joints.And by prolonging the aging time,the thickness of the reaction layer continuously increased,leading to a significant raising of the interfacial stress.The tensile testing results of the SKD/Nb joints match the simulation results well,consolidating accuracy and feasibility of this multilayer model.This study provides an important guidance on the design of DBL to improve the TE joints’mechanical reliability,and a common method to precisely simulate the stress condition in other coating systems.展开更多
文摘热电器件的界面稳定性是决定其服役可靠性和寿命的关键因素。对于方钴矿热电器件,为了抑制高温电极与方钴矿材料之间的相互扩散,需要在两者之间加入阻挡层。本工作选用Ti_(88)Al_(12)作为阻挡层,利用一步法热压烧结制备n型Yb_(0.3)Co_4Sb_(12)/Ti_(88)Al_(12)/Yb_(0.3)Co_4Sb_(12)和p型CeFe3.85Mn0.15Sb12/Ti_(88)Al_(12)/CeFe3.85Mn0.15Sb12样品,研究Ti_(88)Al_(12)阻挡层与热电材料间的界面接触电阻率及微结构在加速老化实验中的演化规律。结果表明:在相同的老化条件下,n型样品的界面接触电阻率增加速度比p型样品慢,其激活能分别为84.1 k J/mol和68.8 k J/mol。对于n型样品,由元素扩散反应生成的金属间化合物中间层的增长及最终AlCo/TiCoSb层的开裂是导致界面接触电阻率增加的主要原因;而p型热电材料与Ti_(88)Al_(12)的热膨胀系数的差异加速了p型样品中界面裂纹的产生。
基金National Key Research and Development Program of China(2018YFB0703600)National Natural Science Foundation of China(51572282,51632010,11572050)Youth Innovation Promotion Association CAS。
文摘In thermoelectric(TE)devices,the interfacial reliability greatly influenced devices’durability and power output.For skutterudites(SKD)devices,TE legs and electrodes are bonded together with diffusion barrier layer(DBL).At elevated temperatures,DBL react with SKD matrix or electrode to generate complex interfacial microstructures,which often accompanies evolutions of the thermal,electrical and mechanical properties at the interfaces.In this work,a finite element model containing the interfacial microstructure characteristics based on the experimental results was built to analyze the interfacial stress state in the skutterudite-based TE joints.A single-layer model was applied to screen out the most important parameters of the coefficient of thermal expansion(CTE)and the modulus of DBL on the first principle stress.The multilayer model considering the interfacial microstructures evolution was built to quantitively simulate the stress state of the TE joints at different aging temperatures and time.The simulation results show that the reactive CoSb2 layer is the weakest layer in both SKD/Nb and SKD/Zr joints.And by prolonging the aging time,the thickness of the reaction layer continuously increased,leading to a significant raising of the interfacial stress.The tensile testing results of the SKD/Nb joints match the simulation results well,consolidating accuracy and feasibility of this multilayer model.This study provides an important guidance on the design of DBL to improve the TE joints’mechanical reliability,and a common method to precisely simulate the stress condition in other coating systems.
