PYROLYTIC LASER-BASED CHEMICAL-VAPOR-DEPOSITION OF TIC COATINGS

TiC layers have been successfully deposited locally on D2 tool steel s pecimens and miniature industrial tools with the aim to improve their mechanical and chemical surface properties. The deposition process was based on a pyrolytically-induced chemical reaction of TiCl4 and CCl4 compounds combined with an atomic hydrogen source. Local heating of th e substrate was achieved by means of a 100 W CO2 laser controlled by a microcomputer-based feedback loop system, involving on-line substrate temperature monitoring. Scanning electron microscopy, energy-dispersi ve X-ray analysis, X-ray diffraction, and transmission electron micros copy analysis showed that close-stoichiometric TiC (fcc structure, lat tice constant a = 4.2 Angstrom) was deposited in the films with a nano crystalline structure. The microhardness of the coatings was in the ra nge 2500-3200 HK.