Tribological Behaviors of B₆O/Si₃N₄ and B₆O/Al₂O₃ Sliding Pairs in Water

Abstract

In this study, B₆O powder compacts were fabricated by spark plasma sintering B₆O powder at 1800°C for 600 seconds. We then investigated the microstructures and mechanical properties of the powder compacts and assessed the tribological behaviors of the powder compacts by sliding them against commercially available Si₃N₄ and Al₂O₃ bearing balls in water at room temperature. The average friction coefficients of the B₆O/Si₃N₄ sliding pairs were as low as 0.17, while the average friction coefficients of the B₆O/Al₂O₃ sliding pairs gradually increased from 0.10 to 0.18. Also, the B₆O/Si₃N₄ sliding pairs showed slightly more stable friction coefficients with smaller error bars than the B₆O/Al₂O₃ sliding pairs 1200 seconds after starting the friction tests. The specific wear rates of the B₆O powder compacts ranged from approximately 2 × 10⁻⁶ to 5 × 10⁻⁶ mm³/Nm when the Si₃N₄ and Al₂O₃ balls were used as the paired materials. We conjectured that the low friction coefficients and low specific wear rates stemmed from the formation of extremely thin H₃BO₃ films on the wear tracks of the powder compacts.

Fig. 4 Friction behaviors of B₆O/Si₃N₄ and B₆O/Al₂O₃ sliding pairs as a function of testing time. The blue and red filled circles represent the average friction coefficients.