Phases and Properties of TiN/TiCN/Al₂O₃/TiN Multilayer Coating Deposited at Different Temperatures

A kind of TiN/TiCN/Al2O3/TiN multilayer coating was deposited on WC-6wt%Co cemented carbide substrate by high temperature chemical vapor deposition at 1 000 ℃, 1 050 ℃ and 1 100 ℃, respectively. The phases, surface and cross-section morphology, micro-hardness, interfacial adhesion and wear resistance of different multilayer coatings were investigated. The results show that the Al2O3 layer consisted of κ-Al2O3 and α-Al2O3 phases at the deposition temperature of 1 000 ℃, while the Al2O3 layer consisted of pure α-Al2O3 at 1 050 ℃ and 1 100 ℃. The surface of the multilayer coatings deposited at 1 050 ℃ was near to smooth and compact, while some small cavities existed in the multilayer coating deposited at 1 000 ℃. When the deposition temperature was 1 100 ℃, the columnar grains in TiCN coating of the multilayer coating grew evidently along a certain direction, the higher deposition temperature accelerated Ti element diffusing outward into the Al2O3 layer. The multilayer coating deposited at 1 050 ℃ had the largest micro-hardness of 1 828 HV and best wear resistance, and it also had the best interfacial adhesion, the critical load was 135.2 N.