氮化硅/石墨激光合金化涂层的组织结构与性能研究

Microstructure and Performance of Laser Alloying Si_3N_4/Graphite Composite Coating

为获得金属表面特别是高副接触金属表面含自润滑特性且具有高硬度耐磨特性的功能材料 ,研究了 45 # 钢表面激光合金化氮化硅 /石墨复合涂层的工艺方法、组织特征、界面形态及其形成机制 ,利用光学显微镜、扫描电镜和X射线能谱对所形成合金化层的元素分布和含量进行了分析 ,并对试样硬度进行了测定。结果表明 ,合金化层中元素Fe ,Co ,Si,C分布均匀 ;C含量达到了 15 6 9%,大部分以石墨的形式存在 ,具有一定的自润滑性能 ;但在形成合金化层的温度条件下 ,氮化硅分解严重 ;合金化层硬度提高的主要原因是Si Fe ,Co Fe固溶体的强化作用及高碳马氏体的生成和高硬度碳化物的存在。

In order to obtain the self-lubricating and antiwear composite coating with high hardness for tribological metal surfaces, especially for line-or point-contact surfaces, the technique and microstructure of the laser alloying coating of Si3N4/graphite composite materials on 45# carbon steel, and the interface between the coating and substrate are studied. The distribution and content of the elements in the alloyed coating are examined and analyzed with OM, SEM and EDS, and the micro-hardness along the depth is measured. Results show that silicon nitride in the coating decomposes completely during laser scanning, but Fe, Co, Si and C distribute evenly on the cross section and the content of C reaches 15.69%. The existing form of most C is graphite, which has self-lubricating property. At the same time, the surface micro-hardness has been improved by solid solution mechanism of Si-Fe, Co-Fe and martensite.