Metallurgical and mechanical characterization of TiCN/TiAlN and TiAlN/TiCN bilayer nitride coatings

Abstract In the present work, attempt has been made to analyse the metallurgical and mechanical characterization of Titanium Carbonitride (TiCN) and Titanium Aluminium Nitride (TiAlN) duplex coatings. TiCN/TiAlN and TiAlN/TiCN bilayer combinations were deposited on cemented carbide cutting insert substrates by means of the cathodic arc physical vapour deposition (CAPVD) process. The metallography analysis revealed a highly densed uniform structure and a fewer voids for the TiAlN/TiCN bilayer coating when compared to TiCN/TiAlN combination. Nano-indentation analysis was performed for the assessment of the surface hardness of the coatings followed by the measurement of adhesive strength through use of a scratch tester. The TiAlN/TiCN bilayer coating revealed a higher hardness and greater adhesion strength than the TiCN/TiAlN bilayer coating. Roughness parameters of the coated films were obtained using atomic force microscopy (AFM). TiAlN/TiCN bilayer coating showed a smooth surface, when compared to TiCN/TiAlN bilayer coating.