Wear damage of TiTaCN-Co cermets at room and elevated temperatures

Abstract

The work is focused on microstructure, mechanical and tribological properties of TiTaCN-Co based complex solid solution cermets with different graphite addition (0, 1.8, 2.2 %) with the typical use as cutting tools. The materials were prepared by the way of mechanochemical MSR (mechanically induced self-sustaining reaction), using a high energy milling of the starting constituents - Ti, Ta, C, and Co in nitrogen atmosphere. Then they were compacted by cold isostatic pressing and sintered at 1500 °C. Microstructure of the obtained materials was studied by SEM/EDX and assessed by image analysis. Hardness and indentation toughness were evaluated using Vickers indentation. Tribological tests were carried out on the high temperature tribometer THT Tribometer (CSM Instruments) to obtain friction coefficient. Ball-on-disc method was used. Wear testing was carried out under following conditions: normal load 5N, sliding distance 300 m, linear sliding velocity 0.1 m/s, atmosphere: air, temperatures: 25 °C, 200 °C, 400 °C, tribological static partners were WC-Co ball and steel ball with 6mm diameter. Created wear track was observed using scanning electron microscopy to identify wear mechanisms. Area of the wear track cross-section was measured using 3D optical profiler (SENSOFAR Plu neox) and the specific wear rate in terms of the volume loss was calculated according to the international standard ISO 20808.