Evaluation of tribological behavior of B4C–hBN ceramic composites under water-lubricated condition

The aim of this study is to evaluate the influence of hexagonal boron nitride (hBN) addition on the tribological behavior of B4C-based ceramic composites under distilled water lubrication. Water-lubricated sliding tests of hot-pressed B4C–hBN ceramic composites with different hBN amounts against pure B4C ceramic were carried out on a pin-disc type wear apparatus. It was found that the addition of hBN into B4C ceramic matrix resulted in a severe decrease of the friction coefficient from 0.373 for B4C/B4C sliding pair to 0.005 for B4C–20 wt% hBN/B4C sliding pair. A B2O3 tribochemical film formed on the worn surface of the B4C–hBN specimen protected both B4C–hBN and B4C and facilitated the frictional surfaces to smooth. Therefore, the tribological behaviors of the pairs were significantly improved. The formation process of the film and its antifriction mechanism are discussed.