Mechanisms of material removal during high temperature fretting of TiCN-Ni based cermets

Abstract

In recent times, TiCN-based cermets containing transition metal carbides are considered as potential cutting tool inserts due to their superior properties like high hardness with improved toughness, wear resistance with chemical stability and thermal shock resistance. During dry machining, tool inserts are subjected to severe stresses and high temperatures. In the above backdrop, the present work reports the very first investigation of friction and wear properties of TiCN-Ni cermets, containing 10 wt% of four different secondary carbides (WC, NbC, TaC or HfC) at fretting contacts against bearing grade steel at 550 °C. An important objective of the present investigation is to evaluate dominant mechanisms, responsible for material removal of cermets using SEM-EDS and to correlate with the wear properties. No significant variation of steady state coefficient of friction (0.43-0.46) is recorded and the wear rate varies in the order of 10-6 mm3/N m for the investigated cermets. Based on SEM-EDS analysis, the observed difference in wear mechanisms among investigated cermets has been explained in terms of the thermal oxidation, stability of the tribochemical layer as well as mutual transfer of materials at the tribological interface. © 2008 Elsevier Ltd. All rights reserved.