TIC AND TIN COATINGS FORMED ON SI3N4-TIC COMPOSITE CERAMICS BY CHEMICAL VAPOR-DEPOSITION

Titanium carbide (TiC) and titnaium nitride (TiN) films were deposited on Si3N4-TiC composite cutting tools by chemical vapor deposition using TiCl4-CH4-H2 and TiCl4-H2-N2 gas mixtures respectively. An Auger electron spectroscopy survey was performed in order to find out the non-metal to metal ratio of the coated layer at various deposition conditions. Nearly stoichiometric films could be obtained with mC:Ti=1.15-1.61 for TiC and with mN:Ti=25-28 for TiN. The microstructure and thermal shock resistance of the coated layer were also investigated. Experimental results show that TiC coatings have an equiaxed structure and TiN coatings have a columnar structure with a (220) preferred orientation. Also, TiC coatings on Si3N4-TiC ceramics have more resistance to thermal shock than do TiN coatings.