Effect of Surface Pretreatment States of Cemented Carbide on the Structure and Mechanical Properties of TiAlCrSiN/TiAlN Coating

TiAlCrSiN/TiAlN coatings were prepared on different pretreated cemented carbides using arc ion plating technology. The surface state of cemented carbide substrates and coating structure, mechanical properties and bonding strength of the as-deposited coating were studied using scanning electron microscopy, X-ray diffraction, nano-indentation and indentation methods. The results show that the surface of the polished cemented carbide was very flat, with a surface roughness as low as 7.7 nm. Pickling treatment dissolved the Co phase in the surface of the cemented carbide and exposed more hard phases, resulting in an increase in surface roughness. The growth rate of TiAlCrSiN/TiAlN coating on the pickled cemented carbide increased, with small grains, high hardness and elastic modulus, but low hard modulus. Sandblasting treatment caused plastic deformation of the Co phase and enveloped more hard phases, resulting in a significant increase in surface roughness. The growth rate of TiAlCrSiN/TiAlN coating on the sandblasted cemented carbide was slightly reduced, with coarse grains, low hardness and elastic modulus, but high hard modulus. The hardness, elastic modulus, and the ratio of hardness to elastic modulus of TiAlCrSiN/TiAlN coating deposited on cemented carbide with duplex pretreatment of pickling and sandblasting were between those of coatings by the two separate treatment methods.