纯铁表面三价镀铬/渗氮复合处理制备CrN/Cr_2N涂层

CrN/Cr_2N coating prepared by trivalent chromium electroplating and nitriding on pure iron

采用预三价镀铬再穿透气体渗氮的方法,在纯铁表面制备CrN/Cr_2N涂层。研究不同镀铬层厚度、渗氮温度和时间所形成涂层的微观结构和相组成变化规律。随渗氮温度从540℃提高到700℃,镀铬层相结构变化为:Cr→CrN/Cr_2N(具有超点阵结构的Cr_2N)→CrN/Cr_2N。在同一温度(640℃)渗氮,随时间延长,Cr→CrN/Cr_2N,形成大量具有超点阵结构的Cr_2N相。SEM/EPMA测试结果表明,采用该复合处理制备的氮化铬层与基体间可形成互扩散的冶金结合,实现氮化铬层与基体间在组织结构上的平缓过渡,有利于提高涂层性能。

CrN/Cr2N coating was prepared on the pure iron surface by trivalent chromium electroplating and penetrating nitriding. The transformation of microstructure and phase composition of the coatings was investigated under different plating thickness, nitriding temperature and time. The results show that the phase composition of the coating changes in a sequence of Cr→CrN/Cr2N （with a superlattice structure）→ CrN/Cr2 N with the increasing of nitriding temperature from 540 T： to 700 ℃. The phase transformation of Cr→ CrN/Cr2N happens by nitriding at 640 ℃ with the increasing of time, and a lot of superlattice structure Cr2N phase precipitates. SEM/ EPMA analysis shows that the metallurgical bonding interdiffusion layer is formed between the coating and substrate, which are benefit to improve the coating property effectively.