TIC COATINGS PREPARED BY PULSED-LASER DEPOSITION AND MAGNETRON SPUTTERING

Tribological properties of TiC coatings grown by pulsed laser depositi on (PLD) and magnetron sputtering were investigated. The PLD TiC coati ngs grown at room temperature were found to be much harder than the Ti C coatings grown by magnetron sputtering under the given experimental conditions. The hardness of PLD coatings deposited at room temperature was as high as 44 GPa, in contrast to similar to 20 GPa of the magnet ron sputtered ones. The coefficient of friction of the PLD films measu red with a pin-on-disk type tribometer had a typical value of about 0. 2 when using a 440C stainless steel pin. Scratch tests indicated that magnetron-sputtered TiC coatings adhered well to the stainless steel s ubstrates. The relatively poor adhesion of the PLD coatings obtained f rom this scratch test was probably partly due to their high brittlenes s and the relatively weak adhesive bond. However, the adhesion of PLD coatings could be improved by raising the substrate temperature slight ly to 300 degrees C or by in situ laser annealing. The former was also able to maintain their hardness at a relatively high level. The adhes ion of magnetron-sputtered TiC coatings could be modified by inserting a metallic interlayer between the coating and stainless steel substra te. Mo interlayer had a detrimental effect on the adhesion caused prob ably by the poor stress bearing capability of the porous Mo film depos ited at low temperature. However, the insertion of both Ti and Cr inte rlayers enhanced the adhesion of TiC by as much as 25%.