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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。
Cr3 / Cr2N coating was prepared on the surface of pure iron by pre-trivalent chromium plating and then nitriding gas. The microstructure and phase composition of coatings formed by different chrome plating thickness, nitriding temperature and time were studied. With the increase of nitriding temperature from 540 ℃ to 700 ℃, the chromate phase structure changes as follows: Cr → CrN / Cr_2N (Cr_2N with superlattice structure) → CrN / Cr_2N. At the same temperature (640 ℃) nitriding, with the extension of time, Cr → CrN / Cr_2N, a large number of super-lattice structure of Cr_2N phase. SEM / EPMA test results show that the intermetallic diffusion can be formed between the chromium nitride layer and the matrix prepared by the composite treatment, so as to achieve a smooth transition between the chromium nitride layer and the matrix on the microstructure and improve the coating performance .