感应加热金刚石/镍基复合涂层微观组织与性能

Microstructure and properties of diamond/Ni-based composite coating by induction heating

摘要:

采用感应加热的方式,在65Mn钢基体表面制备了金刚石质量分数为10%的的复合镍基涂层,利用SEM、EPMA、XRD对钎涂接头的微观组织和相组成进行了分析,研究了感应钎涂中金刚石/钎料界面的元素扩散机制和形成机理。并利用干砂橡胶轮磨损试验机测试了涂层的耐磨性能,分析了金刚石/镍基涂层的耐磨增强机制。结果表明,钎涂层中钎料合金物相主要为Ni4B3、(Ni,Fe)固溶体、Ni3Si2、CrB；金刚石与钎料合金发生了冶金反应,金刚石/钎料合金界面的C元素分布促使金刚石表面出现了双层碳化物结构,分别为金刚石侧的Cr3C2和在Cr3C2表面生长的Cr7C3。金刚石复合涂层的耐磨性能显著优于钢基体,涂层60min磨损失重仅0.25g,为钢对比试样磨损失重的1/12,金刚石在磨损过程中起到了阻挡犁沟扩展的作用,涂层的失效机制为镍基合金磨损和金刚石的脱落。

Abstract:

A composite Ni-based coating with diamond mass fraction of 10% was prepared on the surface of 65Mn steel by induction heating. The microstructure and phase composition of the brazing joint were analyzed by SEM, EPMA and XRD. The element diffusion mechanism and formation mechanism of diamond/filler interface in induction brazing were studied. The wear resistance of the coating was tested by dry sand rubber wheel wear tester, and the wear resistance enhancement mechanism of diamond/Ni-based coating was analyzed. The results show that the main phases of filler alloy in brazing coating are Ni4B3, (Ni, Fe) solid solution, Ni3Si2 and CrB. The diamond and the filler alloy react in metallurgy, and the distribution of C element at the interface of diamond/filler alloy causes the appearance of double layer carbide structure on diamond surface, which are Cr3C2 on diamond side and Cr7C3 on the surface of Cr3C2 respectively. The wear resistance of the diamond composite coating is significantly better than that of the steel substrate. The wear weight loss of the coating is only 0.25g in 60min, which is 1/12 of that of the steel contrast sample. Diamond plays a role in preventing furrow expansion during the wear process, and the failure mechanism of the coating is Ni-based alloy wear and diamond shedding.