Preparation and Performance of CrN and DLC Coatings on TC4 Titanium Alloy

CrN and DLC coatings were deposited on TC4 titanium alloy by physical vapor deposition (PVD). Surface and section morphology, coating thickness, hardness were characterized by SEM, optical microscope, VHM-I04 microhardness tester.Bonding strength, surface roughness of DLC coating and the tribological properties were also investigated in this article.Resultsindicated that the thickness of CrN coating was 5.12 μm, the microhardness was HV 1 267, the bonding force between the TC4 substrate and CrN coating was about 22.95 N. DLC coating was composed of nanoparticles, the thickness was 2.30 μm, the microhardness was HV 2 176, the film substrate interfacial bonding force was 24.85 N, the surface roughness of DLC coating was 4.86 nm. Compared with naked TC4 alloy and CrN coating, the friction coefficient of DLC coating was only 0.073.