In this article, Ti (C, N)-based cermets with Ni, Co and Fe binder phase were manufactured by traditional powder metallurgical techniques. The multilayer TiN/Al2O3/Ti (C, N)/TiN CVD (chemical vapor deposition) coatings were deposited on the three kind of cermets, and the growth and properties of the coatings were studied. The results show that massive cores-incomplete rims are found in the cermet-Ni (cermets with Ni binder) and cermet-Fe (cermets with Fe binder), while in the cermet-Co (cermets with Co binder), the small black cores are surrounded by a complete and well-developed rim phase. When the TiN coating is deposited on the cermets with cores-incomplete rims, the Ti and N atoms stack on the face-centered cubic structure of Ti (C, N) first, and epitaxial growth of the TiN crystals takes place. The epitaxial growth is attributed to the same preferred orientation (2 0 0) of the TiN layers to the Ti (C, N) of the substrate. While on the cermets with cores-complete rims, (Mo, Ti) (C, N) solid solution and binder phase (Ni/Co/Fe), which has a distinct crystal structure or lattice parameters, TiN grains nucleate first and then grow. In this case, the TiN coatings show a (1 1 1)-oriented structure. Dense and thin coatings grow on the cermets-Co. The adhesion of the multilayer coatings to the substrate increases in the order cermets-Fe, cermets-Ni and cermets-Co. In addition, the coating on the cermets-Co has the lowest COF (coefficient of friction) as the thin TiN layer (0.7 μm) is propitious to diffusion of Al and O, and a protective transfer layer is formed by AlOx.
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The study is financially supported by the National Natural Science Foundation of China (Nos. 51634006, 51575368). The authors thank the Chengdu Mingwu Technology Corp., Ltd., of China, Chengdu Tool Research Institute Co., Ltd., of China. We also appreciate Wang Hui from the Analytical & Testing Center of Sichuan University for her help with SEM characterization. Thanks are also extended to the National Engineering Research Center for Biomaterials of Sichuan University for the testing of the samples.