Influence of substrate roughness on structure and mechanical property of TiAlN coating fabricated by cathodic arc evaporation

The aim of the present research was to investigate the influence of different substrate roughness on structure and mechanical properties of Titanium Aluminium Nitride (TiAlN) coatings. Tungsten carbide rectangular block was used as substrate. Different surface roughness was achieved by using grinding discs with different grain sizes and diamond polishing powder, and TiAlN coatings were deposited on these substrates under the same preparation technique and parameters. Morphologies of substrates and coatings, crystal structure, thickness and mechanical properties of coatings were investigated using optical microscope, AFM, XRD, CSM scratch tester and tribometer. It was shown that surface morphology of cathodic arc TiAlN coating was mainly affected by the morphology of the substrate surface and the coating growth process. The influence of substrate roughness on crystal structure and thickness of the coatings could be ignored. With the decreasing of the substrate roughness, the adhesion force between coating and substrate increased. Three stresses model was applied to interpret this result. The wear resistance of the coating was also improved with decreasing the substrate roughness.