Structure and properties of the multi-component TiAlSiN coatings obtained in the PVD process in the nitride tool ceramics

Comprehensive structure and properties investigation results of the multilayer, multi-component PVD coatings developed on the Si3N4 nitride tool ceramics substrate are presented in the paper. The detailed results are presented of examinations carried out on the transmission and scanning electron microscopes, as well as of the mechanical properties and tribological tests of the investigated coatings. Examinations of the chemical compositions of the deposited coatings were also carried out using the X-ray energy dispersive spectrograph EDS, glow-discharge optical emission spectroscope GDOS, and using the X-ray diffractometer. The inserts made from Si3N4 were multilayer coated in the PVD process with the TiN, TiN + multiTiAlSiN + TiN, TiN + TiAlSiN + TiN, and TiN + TiAlSiN + AlSiTiN coatings. Additional investigations were carried out to compare coatings obtained in this way on inserts from various manufacturers offering the nitride tool ceramics with the CVD coatings based on the Al2O3 and TiN layers. Basing on the metallographic examinations results it was found out that the multilayer PVD and CVD coatings were uniformly put down onto the substrate and the particular layers adhere closely to each other. It was found out in the microhardness tests of the coatings that the TiN + multiTiAlSiN + TiN one has the highest hardness. It was demonstrated also that all CVD coatings are characterised by very good adhesion to the substrate compared to the PVD coatings. Results of the X-ray qualitative phase analysis confirm occurrences of phases coming from coatings and the substrate. Analyses of the chemical composition - EDS and GDOS confirm presence of both titanium, aluminium, silicon, nitrogen, and oxygen in the investigated coatings and of silicon and nitrogen in the investigated substrate. (C) 2004 Elsevier B.V. All rights reserved.