AgNi Alloy As a Suitable Barrier Layer Material for NbFeSb-Based Half-Heusler Thermoelectric Modules
AgNi Alloy As a Suitable Barrier Layer Material for NbFeSb-Based Half-Heusler Thermoelectric Modules
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AgNi 合金作为 NbFeSb 基 Half-Heusler 热电模块的合适势垒层材料
DOI：
10.1007/s11664-019-07514-x
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发表时间：
2019
影响因子：
2.1
通讯作者：
Li Junqin
中科院分区：
文献类型：
--
作者：
Zhu Jiaxu;Liu Fusheng;Gong Bo;Wang Xiao;Ao Weiqin;Zhang Chaohua;Li Yu;Hu Lipeng;Xie Heping;Gu Kunming;Li Junqin
作为一类中高温热电材料，半赫斯勒热电材料在功率因数和机械性能方面具有独特的优势，FeNb0.88Hf0.12Sb的品质因数（ZT）在600℃时达到1.0。本文在综合考虑导电性、导热性、熔点和金属活性等因素后，选择银（Ag）作为阻挡层材料。使用放电等离子烧结通过原子扩散将阻挡层和热电材料焊接在一起。烧结后连接表面没有明显的元素扩散，表明Ag对FeNb0.88Hf0.12Sb的性能没有影响。然而，在时效过程中，接合面出现了许多裂纹。在进一步的实验中，我们在Ag中添加了少量的镍（Ni），以实现势垒层和FeNb0.88Hf0.12Sb之间的紧密连接。此外，我们分析了老化192小时后金属间化合物的界面，结果表明在界面处形成了Ni3Nb和Ni6Nb7化合物。采用扫描探针法测试接触电阻，测得阻挡层的电阻率为0.4 μΩ cm2，远小于其他阻挡层的电阻率。此外，连接强度大于40MPa。当采用Ag0.9Ni0.1作为势垒层组成half-Heusler热电模块时，热电转换效率达到7.33%，并且在循环测试过程中效率没有明显下降。
As a type of moderate- and high-temperature thermoelectric materials, half-Heusler thermoelectric materials have a unique advantage in terms of their power factors and mechanical properties, and the figure of merit (ZT) of FeNb0.88Hf0.12Sb reaches 1.0 at 600°C. In this paper, after taking into account factors such as electrical conductivity, thermal conductivity, melting point, and metal activity, silver (Ag) was selected as the barrier layer material. The barrier layer and thermoelectric materials were welded together by atomic diffusion using spark plasma sintering. There was no obvious elemental diffusion on the connection surface after sintering, indicating that Ag did not impact the performance of FeNb0.88Hf0.12Sb. However, many cracks appeared on the joint surface during the aging process. In further experiments, we added a small amount of nickel (Ni) into the Ag to achieve a close connection between the barrier layer and FeNb0.88Hf0.12Sb. Moreover, we analyzed the interface of the intermetallic compounds after aging for 192 h, which showed that Ni3Nb and Ni6Nb7compounds formed at the interface. The contact resistance was tested by a scanning probe method, and the resistivity of the barrier layer was determined to be 0.4 μΩ cm2, which is far less than that of other barrier layers. Moreover, the connection strength was greater than 40 MPa. When Ag0.9Ni0.1was used as the barrier layer to compose the half-Heusler thermoelectric module, the thermoelectric conversion efficiency reached 7.33%, and there was no significant decrease in efficiency during the cyclic test.