定向凝固镍基复合涂层的摩擦磨损性能

Wear Behavior of Ni-base Composite Coating With Directional Solidification Structure

用真空熔覆技术在ZG45表面制备出20%WC+Ni和5%G+20%WC+Ni复合涂层,研究了涂层的微观组织结构和常温摩擦磨损性能,揭示了磨损机理。结果表明:复合涂层由Ni基固溶体和Fe3Ni等硬质相组成,组织致密,与基体结合良好,微观组织具有定向凝固组织特征;涂层内和涂层与基体的结合界面处没有夹杂孔洞等缺陷;在摩擦参数相同的情况下5%G+20%WC+Ni涂层的摩擦系数及其波动范围和磨损量均低于20%WC+Ni涂层;20%WC+Ni涂层的磨损率随着频率的增大而增加,而5%G+20%WC+Ni复合涂层的磨损率的变化情况则相反;20%WC+Ni涂层以磨粒磨损与氧化磨损为主,5%G+20%WC+Ni涂层为微片层脆性断裂与氧化磨损为主。

The composite 20%WC＋Ni and 5%G＋20%WC＋Ni coatings were prepared by vacuum clad- ding method on the ZG45 substrate. Microstructures, forming mechanism for the coatings and the tribo- logical properties were investigated. The results show that the microstructure of composite coating is dense, and there are not any inclusion and pores at the interface of the coating and substrate. The main composition of coating is Ni- based solid solution and hard intermetalic compounds. The major influential factor of the isomeric microstructure is the directional solidification during metal solidification. The wear re- suits show that the friction coefficient and fluctuation are lower than that of 20%WC ＋ Ni coating for the of friction coefficient of 5%G ＋ 20%WC＋ Ni coating same wearing testing parameters. The wear rate of 20%WC ＋ Ni coating increases with the increasing wear frequency, whereas the wear rate of 5%G ＋ 20% WC ＋ Ni coating decreases with the increasing wear frequency. The abrasive wear and oxidation wear dominate the wearing process of 20%WC ＋ Ni coating, and the oxidation wear and micro-crack lamellar for 5%G＋20%WC＋Ni coating.