Friction and wear behaviors of WC/Co cemented carbide tool materials with different WC grain sizes at temperatures up to 600 °C

The friction and wear behaviors of WC/Co cemented carbide tool materials with average WC grain sizes ranging from 0.6 to 2.2 mu m were evaluated in ambient air at temperatures up to 600 degrees C using a ball-on-disk high temperature tribometer. The friction coefficient and wear rate were measured. The microstructural changes and the wear surface features of the WC/Co cemented carbides were examined by scanning electron microscopy. Results showed that the friction coefficient of WC/Co cemented carbides decreased with the increase of test temperature. All the tested samples showed the highest friction coefficient when sliding at 200 degrees C, and exhibited the lowest friction coefficient in the case of 600 degrees C. The wear rate of WC/Co cemented carbides increased with the increase of test temperature. The cemented carbide with the smallest WC grain size showed improved wear resistance at temperature up to 600 degrees C, which corresponds to its higher value of hardness. The difference of the worn surface features of the WC/Co cemented carbide after sliding at different temperature is related to the chemical transformation during sliding wear tests. Abrasion and grain cracking seemed to be the main wear types at temperature less than 200 degrees C, the wear owing to binder removal by plastic deformation and grain pull out were suggested to be the main wear mechanism at intermediate temperature, while the mechanism of oxidative wear dominated at 600 degrees C. (C) 2011 Elsevier Ltd. All rights reserved.