Ag-MAX电接触材料的制备与性能研究

Electrical contact materials are essential to the parts which connect or break the electric circuits. “All-purpose” silver-based electrical contact material, AgCdO, is restricted due to the Cd toxicity. However, AgCdO is still used in our country and it is also widely used in international aerospace industry, which is apparently due to the limitation of its substitute materials. Machinable, electrical conductive ceramic MAX phases possess properties matching the requirements for contact materials. Our preliminary experimental results indicated the feasibility of the fabrication of Ag-MAX composites, with promising electrical properties and superior arc erosion resistance to current commercial electrical contact materials. This project will select MAX phases with good wettability with Ag, according to our long year experience on MAX phases and experimental research. Improved wettability will benefit the following pressureless sintering process and the arc erosion resistance of the composite materials. Ag-MAX composite will be fabricated with optimized sintering process and the relationship between the sintering parameters and the microstructure, mechanical properties, electrical conductivity, and thermal conductivity will be established. Arc erosion experiments will be carried out with the arc reaction on the contact surface real-time observed. The effect of arc on the surface morphology, interface structure and so forth will be investigated to reveal the arc erosion mechanisms. Models for the optimization of arc erosion resistance of the Ag-MAX materials will be proposed. The achievements of this research project will benefit the international competitiveness of our national electrical industries, the acceleration of toxicity-free electrical contact materials, and the effective utilization of noble metal resource of Ag.

电接触材料是电路接通与分断元件的“心脏”。“万能”银基电接触材料AgCdO因镉毒而被明令限制，但由于替代材料的局限性，我国还在使用，国际航天领域也在大量使用。可加工导电陶瓷MAX相材料的性能特征与电接触材料的性能要求有很大的一致性，前期实验显示Ag-MAX复合材料的制备可行而且具有良好的导电性，而且耐电弧侵蚀性能优于现行商用电触头。本项目将基于MAX相材料的工作基础和实验研究，优选出与银液润湿性良好、满足无压烧结以及耐电弧侵蚀性能的MAX相体系；确立Ag-MAX的制备工艺；阐明烧结参数与微观组织、力学性能及导电导热等物理性能之间的关系；通过实时观察电弧与触头的反应过程，分析电弧作用对材料的表面、相界面的影响，阐明Ag-MAX的电弧侵蚀机理；提出耐电弧侵蚀的Ag-MAX材料学优化方案。研究成果将有助于提升我国电接触元件产业国际竞争力、加速电接触材料的无毒化、以及有效利用贵金属银资源。

针对Ag基电触头增强相CdO材料的替代问题，本项目以Ti3AlC2、Ti3SiC2、Ti2AlC、Ti2SnC等代表性MAX相为主要研究对象，系统研究了Ag-MAX复合电接触材料的设计、制备、结构和性能优化以及抗电弧侵蚀机理等关键科学与技术问题，同时还在MAX衍生材料MXene增强Ag基电触头方面进行了探索性研究。.主要研究内容包括以下几个方面：以MAX相与Ag的界面结合为出发点，通过高温润湿性实验研究了Ag-MAX（MXene）体系的润湿行为与机理，明确了Ag-MAX强界面结合来自于A原子层与Ag基体间的相互扩散；在无压条件下，系统研究了代表性MAX相（Ti3AlC2、Ti2AlC、Ti2SnC）高纯粉末的快速合成技术及机理；系统研究了组分、工艺对Ag-MAX复合电接触材料物相、结构、物理性能及电接触性能的影响规律和机制；结合第一性原理计算，深入揭示了Ag-MAX界面反应机理，并分析了其与复合材料物理和电接触性能之间的关系；采用动态放电实验，深入分析了电接触过程中MAX、Ag、电弧三者之间相互作用机制，进而阐明了Ag-MAX复合电接触材料的抗电弧侵蚀机理。.研究结果确定了A原子层的活性在Ag-MAX体系润湿行为、界面反应、抗电弧侵蚀过程中的关键作用；明确了综合性能优异条件下Ag-MAX复合电接触材料的关键组分和制备工艺；提出了Ag-MAX复合材料独特的抗电弧侵蚀机理和材料退变模型，为解决新时代背景下Ag基电接触材料的环保问题提供了突破方向，有望进入实际应用。本项目资助期间共发表论文40篇，其中SCI检索36篇，申请专利17项，参加学术会议并做交流报告20余人次。