Tribological Behavior of B₄C/hBN Ceramic Composites Sliding against Ductile Iron in Emulsion

In this paper, pure boron carbide (B₄C) and boron carbide/boron nitride (mass fraction of 30%) ceramic composites (B₄C/hBN), both fabricated via hot press sintering, were coupled with ductile iron (QT) under the lubrication condition of full immersed emulsion and drop feeding emulsion. By virtue of the observation of worn surfaces and the component analysis of the emulsion before and after the test, combined the law of friction coefficient and wear rate of each couple in the meantime, the wear and lubrication mechanisms of both couple in full immersed and drop feeding emulsion were clarified. The results show that, under the lubricating condition of full immersed emulsion, with the increase of sliding distance, the friction coefficient of B₄C coupled with QT was as low as 0.03 and the fluid lubrication regime was established. While that of B₄C/hBN ceramic composites coupled with QT was higher than 0.1. On the contrary, under the lubrication of drop feeding emulsion, the friction coefficient of B₄C/hBN ceramic composites coupled with QT was 0.003 while that of B₄C coupled with QT was higher than 0.1.