Evaluation of a flexible physical vapor deposited TiC-C coating system

Physical vapor deposited (PVD) TiC-C coatings with different amounts of fre e carbon have been investigated with respect to their microstructure. mecha nical and tribological properties. The coatings were deposited using a plas ma assisted PVD process which combines evaporation of titanium and sputteri ng of carbon. The carbon content was controlled by means of the magnetron p ower. X-ray photoelectron spectroscopy was used to study the chemical composition . X-ray diffraction and transmission electron microscopy were utilised to o btain information about phase composition and microstructure. It was found that the mechanical properties varied immensely with the: carb on content in the coatings. Coating hardness and elastic modulus both decre ased dramatically with increasing carbon content. The hardness dropped from 44 to 13 GPa, and the elastic modulus from 430 to 160 GPa, as the carbon c ontent was increased from 33 to 70 at.%. All coatings provided very low fri ction coefficients, between 0.14 and 0.20, as tested against a steel ball i n a ball-on-disc test. The TiC-C coating system proved to be easy to control with respect to mecha nical properties. Together with good tribological properties this makes it possible to tailor these coatings to suite different applications as well a s substrate materials. (C) 2000 Elsevier Science S.A. All rights reserved.