Deposition of refractory coatings by LCVD

Abstract

TiC layers have been successfully deposited locally on tool steel specimens and real small industrial tools in order to improve their mechanical and corrosion properties. TiC films have been produced by the pyrolytic laser chemical vapour deposition technique, using a low power RF-modulated CO2 laser and a gas mixture of TiCl4/CCl4/H-2/H/Ar. The surface temperature was monitored by a microcomputer-based feedback loop system that was specially developed and integrated to control the laser. SEM, EDX, XRD and TEM analysis showed that close stoichiometric TIC (fee structure, lattice constant a = 4.2 Angstrom) was deposited in the films with nanocrystalline structure. The microhardness of the coatings was in the range 2500-3200 HK. Furthermore, an ArF excimer laser was used to enhance the deposition rate.