Effect of grain size on tribological behavior of hot-pressed boron carbide sliding against alumina balls

Boron carbide ceramics (B4C) have extraordinary hardness and well-abrasive resistance, while the tribological behavior of ceramic materials is complicated, which are affected by microstructures, mechanical properties, and surface characteristics, and so on. In this paper, the effect of grain size on the mechanical properties especially the wear resistance of hot-pressed B4C was investigated. The average coefficient of friction of the B4C/Al2O3 friction pair ranges from .41 to .66. The sample with the minimum grain size possesses the lowest wear rate of about 2.15 x 10-6-7.66 x 10-6 mm3 center dot N-1 center dot m-1. The analysis of the wear rate (WR) and grain size (G) indicates that the wear resistance (WR-1) and the reciprocal of the square root of grain size (G-1/2) are in line with the Hall-Petch relation. Fracture and the resulting abrasive wear are the main wear mechanisms of B4C in the dry sliding process. This success provides a theoretical basis and a design approach of microstructure to improve the tribological behavior of ceramic materials.