Tribological Properties and Cutting Performance of AlTiN Coatings with Various Geometric Structures

Abstract

The development of advanced machining techniques requires high-performance tool coatings. To improve the wear resistance and cutting performance of AlTiN coatings, a structure optimization strategy involving bias control and a nano-multilayer architecture strategy is presented. The investigated AlTiN coatings were deposited by cathodic arc evaporation and studied with regard to phase structure, hardness, adhesion, and tribological properties by a combination of X-ray diffraction, nanoindentation, scratch, and ball-on-disk friction tests. A high bias potential (up to −120 V) with enhanced adatom mobility suppressed the formation of the wurtzite structure AlN in AlTiN. In addition, the epitaxial growth of Al0.67Ti0.33N on Al0.5Ti0.5N in the AlTiN nano-multilayer could also promote the single-phase structure. The hardness of AlTiN-based coatings with a dominated cubic structure was 3–4 GPa higher than conventional ones. In addition, the interlayer interfaces in the Al0.67Ti0.33N/Al0.5Ti0.5N multilayer could deflect the cracks and thus improve the fracture toughness. As a consequence, the Al0.67Ti0.33N/Al0.5Ti0.5N multilayer with enhanced mechanical properties obtained the lowest wear rate of 1.1 × 10−5 mm3/N·m and the longest cutting lifetime of 25 min during dry turning the SUS304 stainless steel.