研究了流动Ar和N2对镀铬金刚石热处理后镀层组织的影响,热处理温度分别为450℃、650℃和850℃,采用XRD、SEM和EDS方法对镀层组织进行了研究.研究结果表明,流动Ar时镀层易发生氧化,在较低的温度(如650℃)氧化已经十分显著,不同的是,流动N2氧化温度升高到850℃.在两种气氛下均发现,当热处理温度由650℃升至850℃时,镀层中碳化铬由低C/Cr相Cr7C3向高C/Cr相Cr3C2发生转化,且在氮气条件下转化率更高.上述现象归因于N2与镀层中的Cr反应生成了CrN,阻碍并延迟了镀层的氧化,有利于高温下金刚石表面的C原子与镀层中的Cr原子相互扩散.%Effect of flow Ar and N2 on the microstructure of chromium coating on the diamond after heat treatment was investigated. Heat treatment temperatures were selected as 450℃, 650℃ and 850℃, respectively. The analysis of coating microstructure was conducted by XRD, SEM and EDS. Research results indicate that Ar-flow coating was apt to oxide, especially at lower temperature, i.e. 650℃, at which the oxidation was more evidently. On the contrary, the oxidation temperature in N2-flow coating rised to 850℃. In both atmospheres, it was found that with increasing heat treatment temperature from 650℃ to 850℃, the amount of carbide transformed from Cr7C3 with low C/Cr ratio to Cr3C2 with high C/Cr ratio, and this carbide transformation was enhanced in N2 atmosphere. The results of studying coating by XRD, SEM and EDS indicate that the reaction of N and Cr to form CrN in N2 atmosphere, which both prevented the coating oxidation and enhanced the inter-diffusion of C atom from diamond and Cr atom from coating at high temperature.
展开▼
