金属掺杂对汽车继电器触头材料导电、导热行为的作用机制

The AgSnO2 contact material of the automotive relay has a lot of defects, such as a large contact resistance, high temperature rise, and even the welding fault, which can reduce the reliability of the relay, shorten the electrical life and even influence the safety of the car, resulting in personal injury. In order to solve the problems, the microstructures of SnO2 materials doped with different metals and different proportions were established by the quantum mechanics calculation method based on the first-principles calculation. The mechanism of the conductive properties and thermal conductivity of AgSnO2 contact material was qualitatively analyzed. The electrical and thermal conductivity models of metal-doped AgSnO2 contact material related to electrical and thermal conductivity of substrate and doped metal，volume fraction, particle size, particle shape and so on were established to realize the electrical and thermal conductivity quantitative calculation. The numerical sorting of electrical and thermal conductivity of AgSnO2 contact material was obtained by synthesis of various test results. From which, we choose the best electrical and thermal conductivity of the contact materials of automotive relay, and change the situation that advanced automotive relays imported from abroad and the contact material prepared only by empirical selection of ingredients and content without theoretical basis, for a long time. It provides a powerful theoretical support for the research of environmental-friendly AgSnO2 contact material of the automotive relay.

汽车继电器AgSnO2触头材料存在接触电阻较大、温升较高甚至使继电器发生熔焊的缺陷，易导致继电器可靠性降低，严重时将影响汽车的安全行驶而造成人身伤害。针对上述问题，本项目拟通过基于第一性原理的量子力学计算方法建立不同金属及不同比例掺杂SnO2材料的微观结构，定性分析影响AgSnO2触头材料导电性能、导热性能的机理；建立与基体和掺杂金属电导率和热导率、体积分数、颗粒粒度、颗粒形状等因素相关的金属掺杂AgSnO2触头材料的电导率及热导率模型，实现电导率、热导率的定量计算。综合各种试验结果后得到金属掺杂AgSnO2触头材料的电导率、热导率排序。从中选优以改善汽车继电器触头材料导电、导热性能，改变长期以来仅凭经验选定掺杂金属成分和含量造成极大浪费却未能制备出性能优良的触头材料、高端汽车继电器长期进口的局面。从而为研究绿色环保汽车继电器AgSnO2触头材料提供有力的理论支撑。

汽车继电器AgSnO2触头材料存在接触电阻较大、温升较高甚至使继电器发生熔焊的缺陷，易导致继电器可靠性降低，严重时将影响汽车的安全行驶而造成人身伤害。针对上述问题，进行了如下的研究：.1）建立了不同金属Fe、Bi、Cu、Mg、In、Ce、Nd、Sm、Gd及不同比例(50%、25%、16.7%、12.5%)La和(16.7%、12.5%、8.34%、6.25%)Sr、Co、Ga掺杂SnO2的晶胞模型，并对这些模型进行优化计算，得到优化后的晶胞参数。.2）对上述优化后金属掺杂SnO2的晶胞模型进行了能量计算，对计算得到的带隙值及态密度积分得到的费米能级附近的载流子浓度分析，并比较了不同金属掺杂后SnO2的导电性。计算了SnO2及四种不同浓度La元素(12.5%、16.7%、25%、50%)掺杂的SnO2晶体模型的声子谱、声子态密度及分波态密度和相关热力学参数。对AgSnO2触头材料进行导热性能仿真计算，得到La掺杂AgSnO2触头材料热导率最佳的掺杂比例。.3）采用溶胶-凝胶法制备掺杂的SnO2粉末，通过XRD试验验证了理论计算的正确性。然后将SnO2粉末及掺杂粉末与Ag粉分别按88:12的比例采用高能球磨工艺混合，制备了AgSnO2触头材料，测量了不同金属掺杂AgSnO2触头材料的电导率。还进行了不同颗粒粒度对触头材料电导率等性能影响的研究。.4）对上述不同金属及不同比例La和Sr、Co、Ga掺杂AgSnO2触头材料进行了电接触性能试验，结果验证了仿真计算的可行性与正确性。最终，通过比较筛选出金属掺杂AgSnO2触头材料的综合性能排序：Co(6.25%)>La>Bi>Sr(6.25%)>Gd。.改变长期以来仅凭经验选定掺杂金属成分和含量造成极大浪费却未能制备出性能优良的触头材料导致高端汽车继电器长期进口的局面。从而为研究绿色环保汽车继电器AgSnO2触头材料提供有力的理论支撑。