Tribomechanical Property Modification of Commercial TiN Coatings by Carbon Ion Implantation

Abstract

ABSTRACTAbout 2 μm thick commercial coatings of TiN on high speed steel substrates were implanted at room temperature with 95 keV carbon to nominal doses between 1 × 1017 and 8×1017 ions cm-2. An ultra-microhardness apparatus (UMIS-2000) was used to measure hardness, and a pin-on-disc machine (CSEM Tribometer) with a sapphire ball was used to measure wear, friction and adhesion. Carbon implantation induced a significant improvement in ultra-microhardness, friction coefficient and wear properties. The surface microhardness increases monotonically by up to 115% until a critical dose φ crit is reached. Beyond this dose the hardness decreases, but remains higher than that of unimplanted sample. A lower friction coefficient and a longer transition period towards a steady state condition were obtained by implantation. An improvement of up to four times in the wear is obtained after carbon implantation. Topology studies with SEM show a change in the mode of wear. The changes in tribomechanical properties are discussed in terms of radiation damage and possible second phase formation.