Evaluation of the structure and properties of the hard TiAlN-(TiAlN/CrAlSiN)-TiAlN multiple coatings deposited on different substrate materials

Abstract

Substrate materials have a significant influence on the coating properties, especially on the adhesion of coating to substrate. Therefore, the understanding of the substrate materials effect on deposited coatings will lead to a better performance of the coated cutting tools. In this investigation, the TiAlN-(TiAlN/CrAlSiN)-TiAlN multiple coatings have been prepared by arc ion plating technology on cermet, cemented carbide and high-speed steel substrates, respectively. The effects of substrate materials on microstructure, hardness, adhesion strength as well as tribological properties of the as-deposited coatings were investigated. The results show that the TiAlN-(TiAlN/CrAlSiN)-TiAlN multiple coatings on all substrates exhibit a single (200) preferred fcc-CrN structure with columnar grain morphology. With the finest grains of 16.2 nm and the strong solid solution strengthening effect, the coating deposited on the cermet substrate possesses the highest hardness. However, the TiAlN-(TiAlN/CrAlSiN)-TiAlN multiple coating obtained on the cemented carbide substrate has the highest adhesion of 95 N due to the slightly lower thermal expansion coefficient of the cemented carbide substrate than the inner TiAlN layer as well as the small hardness difference between the cemented carbide substrate and the coating. Owing to the low friction coefficient and high hardness, the TiAlN-(TiAlN/CrAlSiN)-TiAlN multiple coating prepared on the cemented carbide substrate exhibits the best wear resistance. Besides, the wear mechanism of the TiAlN-(TiAlN/CrAlSiN)-TiAlN multiple coatings is the combination of abrasive, oxidative and adhesive wear, which is little affected by the substrate materials.