Study on the microstructure and high temperature friction and wear characteristics of three CVD coated cermets

Abstract

In the paper, three CVD coatings are used to study the microstructure and high-temperature friction and wear properties of the coatings to further guide the selection and process design of cermet surface coating materials. The TiN/TiCN/Al2O3/TiN, TiCN/Al2O3/TiN and TiCN/Al2O3 are called A coating, B coating and C coating, respectively. The result shows that both the α-Al2O3 coating of A and B coatings have a coarse-grained structure and a (104) orientation texture. The TiN and TiCN coating have a nano columnar crystal structure and have (111) and (200) orientation texture. The adhesion of A coating is higher than that of B and C. the A coating process uses the interface layer and the transition layer to control the coating nucleation growth and improve the bonding strength. Compared with B and C coating, the A coating is particularly that by adding Al element to the traditional TiCO and TiCNO transition layer, the MT-TiCN coating is uniformly transitioned to the Al2O3 coating. Through the continuity of the components, the bonding force of the coating is better. This process is beneficial to the subsequent control of the grain size and orientation of the Al2O3 coating. Secondly, the A process is directly deposited on the TiN nanocrystalline grains, and the B process is directly deposited on the cermet substrate. In addition, the affinity of TiN coating is higher than that of TiC-based cermet, resulting in the growth of TiCN coating in A coating better than that of B and C. the friction coefficient of A coating is higher than that of B and C, but the wear rate of A coating is lower than that of B and C. this is related to the surface morphology of the coating such as kurtosis and skewness. The coating wear mechanism is mainly oxidation wear, abrasive wear and adhesive wear