Coatings deposited by physical vapor deposition (PVD) on high-speed steel used in the processing of wood materials

In this study the use of AlTiN/aCN, TiAlN/TiN and three types of CrAlN/CrN coatings deposited on HSS steel was investigated. These protective coatings were prepared using PVD (physical vapor deposition) method. The objective of this study was to compare the microstructure, chemical composition and properties of Cr, Al or Ti based coatings deposited on a substrate made of high-speed steel HSS. The thicknesses of coatings based on titanium were approx. 4 mu m, and those based on chromium were less than 1 mu m. The morphology and chemical composition were studied using scanning electron microscopy (SEM) and X-ray dispersion spectroscopy (EDX). The X-ray photoelectron spectroscopy (XPS) method was applied. The adhesion was evaluated by scratch test. Nanohardness and durability tests of uncoated and coated knifes were performed. It was found that the knifes made of HSS covered with two-layer TiAlN/aCN coating exhibited the best durability characteristic. Coatings containing chromium were less durable due to their small thickness. The highest nanohardness was found in the AlTiN/TiN coating due to its multi-layer nature. The nanohardness of the other coatings is comparable but more than two times lower compared to the multilayer AlTiN/TiN nanocoating.