Role of hBN content, humidity, and temperature on the sliding wear behaviour of SiC ceramics

Abstract

The present investigation demonstrates the feasibility of obtaining a wide range in friction and wear for SiC-hBN composites in sliding conditions: humidity (≤ 20 % RH and ≥ 90 % RH) and temperature (RT and 500 °C) against SiC ball. With an increase in hBN content to 10 vol%, wear rate reduced by an order of magnitude irrespective of humidity at RT and up to 55 % reduction at 500 °C, and coefficient of friction (COF) reduced by 76 % at high-humidity. Friction and wear results corroborate with the transition in material removal mechanism from fracture of SiC grains and pull-out of hBN platelets at ≤ 20 % RH to hydroxylative wear at ≥ 90 % RH and oxidative wear at 500 °C. SiC-10 vol% hBN composites are recommended for wear-resistance applications experiencing extreme conditions of humidity and temperature as well as applications where internal lubrication is the only feasible method for reducing friction.