激光熔敷生成碳硅钛化合物及其组织性能研究

Study on Microstructures and Mechanical Properties of in-situ Formed Multiphase Coatings Produced by Laser Cladding of Titanium Alloy with Silicon and Graphite Mixed Powders

利用CO2 连续激光对预涂石墨和硅混合粉末的Ti 6Al 4V合金进行了熔敷处理。金相分析发现熔敷层内形成了大量的化合物 ,X射线衍射分析证实形成的化合物主要为SiC ,Ti5Si3 和TiC等。电子探针分析表明熔敷层内的初晶化合物主要由SiC和TiC组成 ,共晶化合物则主要是Ti5Si3 。熔敷层与金属基体呈良好的冶金结合 ,其硬度可达 2 0 0 0Hv0 .1,摩擦系数约为 0 3,而基体的硬度约为 32 0Hv0 .1,摩擦系数约 0 5 5。可见熔敷层较基体的硬度大为提高 ,且其耐磨性能较好。激光工艺参数的改变影响着熔敷层的组织和性能 ,调整工艺参数可获得无气孔和裂纹的熔敷层。

A wear resistance multiphase coatings is fabricated by laser cladding of silicon and graphite mixed powders on the substrate of titanium alloy (Ti-6Al-4V). The microstructures and phases in the coatings are investigated by means of electron probe microanalysis (EPMA) and X-ray diffraction (XRD). The results show that a lot of compounds are formed in-situ in the coatings, which are metallurgically bonded to the substrate. The compounds in the coatings are chiefly composed of pre-eutectic SiC, TiC and eutectic Ti 5Si 3. The test results show that the hardness of the coatings is up to 2000 Hv 0.1, much higher than that of the Ti-6Al-4V substrate (about 320 Hv 0.1) and the friction coefficient of the coatings is about 0.3, lower than that of the substrate (about 0.55). Changing the parameters of laser cladding has an effect on the properties and microstructures of the claddings. Thus an ideal claddings freeing from the pores and cracks can be obtained by optimizing the cladding parameters.