反应等离子制备TiC-SiC 基复合涂层及组织调控的研究

TiC-SiC composite coatings were prepared by reactive plasma spraying in this present project. Metaltitanium, graphite and silicon carbide (or silicon) were used as the raw materials, and make them into sprayable composite feedstock. During spraying process, the composite feedstocks were injected into plasma jet directly. This would ignite the self-propagating reactions of Ti and Cto form TiC with high temperature plasma jet, and the SiC would be decomposed into Si and C, which would react with Ti to form Ti3SiC2、Ti5Si3 constitutes. A composition structure with nanoTiC,Ti3SiC2 and un-decomposed micron SiCwould be obtained by adjusting feedstocksratios,preparation processing of powder and spraying processing parameters, so as to achieve the adjustment of coatings’ organization. The reaction mechanism of Ti-C and Ti-C-Si( or SiC) were studied by the combination of water quenching method with measurement of particles’ temperature and size in plasma jet, and obtain the effect law of carbon on the coatings’ composition at the same time. The crystal law of coatings with multi-composites system under deep supercooled conditionswas revealed through the simulation calculation and study of spread out of particles. The effect raw of different materials ratioson the microstructure, high temperature oxidation and friction and wear of composite coatings was illuminated, which would provide theoretical and technical fundament for developing new type high temperature ceramic protection materials.

本课题采用反应等离子喷涂的方法制备TiC-SiC基复合涂层。以石墨、Ti、SiC（或Si）为原料制备成适于喷涂的复合粉，将复合粉送入等离子焰流，借助焰流的高温点燃Ti、C 间的自蔓燃反应形成TiC；利用SiC在高温焰流中分解出的Si、C 与复合粉中的Ti发生反应生成Ti3SiC2、Ti5Si3等产物形成涂层。通过调控复合粉成分配比、粉末制备工艺及喷涂工艺，获得不同含量的纳米晶TiC、Ti3SiC2及未完全分解的微米SiC组成的复合组织，实现涂层的组织调控；采用淬熄方法结合测定颗粒在等离子焰流内温度、粒度的变化，研究Ti-C、Ti-C-Si(SiC)的反应机制，得出碳对涂层产物的影响规律；采用模拟计算的及颗粒铺展的研究，揭示多元系统在深过冷条件下涂层的结晶规律；阐明不同配比制备复合涂层的组织结构及对高温氧化和磨损的影响因素，为新型高温陶瓷防护材料的开发提供理论和技术基础。

本课题的思路是采用反应等离子喷涂的方法制备SiC-TiC复合涂层。课题以石墨、Ti、SiC（或Si）为原料制备成适于喷涂的复合粉，将复合粉送入等离子焰流，借助焰流的高温点燃Ti、C间的自蔓燃反应形成TiC；利用SiC在高温焰流中分解出的Si、C与复合粉中的Ti发生反应生成Ti3SiC2、Ti5Si3等产物。本课题的主要研究内容为：（1）优化了涂层喷涂工艺参数（喷涂功率和喷涂距离）；（2）研究了不同Si源喷涂涂层的结构-性能，实现了涂层物相和结构调控；（3）研究了不同金属助剂对涂层结构和性能的影响规律，金属助剂的添加促使Ti-Si(SiC)-C系反应程度增加，进而改善了涂层质量和性能；（4）研究了热处理对涂层结构和性能的影响规律，分析了热处理对涂层性能的作用机理，得到了热处理与涂层组织结构-性能的关联关系；（5）研究了Ti-Si(SiC)-C系在等离子焰流中反应机制，得出了成分对反应物相的影响规律；（6）研究了涂层结晶规律，涂层晶粒为纳米柱状晶+少量纳米等轴晶。.本项目通过对Ti-Si(SiC)-C系反应机制、结构调控及结晶规律研究，为多组元高熔点碳化物材料设计和制备提供了新途径。.本项目已发表SCI论文26篇；申报专利3项；培养博士1名，研究生6名；参加学术会议3人次。