Influence of Ni-addition on mechanical, tribological properties and oxidation resistance of AlCrSiN coatings

Abstract

AlCrSiN coatings with splendid mechanical and thermal properties have attracted wide attention as excellent alternatives for advanced machining applications. Here, Ni-alloyed AlCrSiN coatings were deposited by cathodic arc evaporation and elaborated with respect to mechanical, tribological and anti-oxidation properties. With the increase of Ni content, multiphase composite structured AlCrSiN-Ni coatings show a sustained decline in hardness, elastic modulus and the ratio of hardness to modulus, which causes the decrease of wear resistance at room temperature and 600 °C. Nevertheless, the addition of Ni effectively enhances the toughness and reduces the friction, especially, at 600 °C, where AlCrSiN, AlCrSiN_Ni5, and AlCrSiN_Ni20 obtained a average friction coefficient of ~0.93, 0.86 and 0.66, respectively. Oxidation kinetics studies at 800 – 1000 °C indicate that Ni-containing coatings have relatively lower activation energies, 173.8 kJ/mol of AlCrSiN_Ni5 and 156.6 kJ/mol of AlCrSiN_Ni20, than 176.5 kJ/mol of AlCrSiN. The faster outward diffusion of Cr in Ni-containing coatings forms a Cr2O3/NiAl2O4 two-layer oxide scale with less protection effect and poor adhesion, leading to inferior oxidation resistance.