方钴矿热电材料/Ti88Al12界面稳定性研究

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Ti₈₈Al₁₂作为阻挡层, 利用一步法热压烧结制备n型Yb_0.3Co₄Sb₁₂/Ti₈₈Al₁₂/Yb_0.3Co₄Sb₁₂和p型CeFe_3.85Mn_0.15Sb₁₂/Ti₈₈Al₁₂/CeFe_3.85Mn_0.15Sb₁₂样品, 研究Ti₈₈Al₁₂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 kJ/mol和68.8 kJ/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Ti₈₈Al₁₂的热膨胀系数的差异加速了p型样品中界面裂纹的产生。

Interface Stability of Skutterudite Thermoelectric Materials/Ti88Al12

Interface stability is one of the key issues determining the service reliability and life of thermoelectric devices. For skutterudite-based thermoelectric devices, the barrier layer is required in order to restrain the inter-diffusion between the hot-side electrode and skutterudite matrix. In this work, Ti₈₈Al₁₂ was selected as the barrier layer. N-type Yb_0.3Co₄Sb₁₂/Ti₈₈Al₁₂/Yb_0.3Co₄Sb₁₂ and p-type CeFe_3.85Mn_0.15Sb₁₂/Ti₈₈Al₁₂/CeFe_3.85Mn_0.15Sb₁₂ thermoelectric joints were prepared by one-step hot pressing sintering method. The evolution processes of contact resistivity and microstructure were studied through accelerated aging experiments. The results show that the contact resistivity of n-type joints increases slower than that of p-type joints under the same aging condition. Activation energy for n-type and p-type joints is 84.1 kJ/mol and 68.8 kJ/mol, respectively. Growth of the inter-metallic compound layer and cracking at the AlCo/TiCoSb interface result in rapidly increased contact resistivity of n-type joints. For p-type joints, the difference of coefficient of thermal expansion between CeFe_3.85Mn_0.15Sb₁₂ and Ti₈₈Al₁₂ becomes the main reason for the cracks.