Effect of vanadium and temperature on the tribological properties of gray cast iron

In this study, the effect of vanadium (V) content on the tribological properties of gray cast iron (GCI) was investigated at room temperature, 100 °C, and 600 °C. The following conclusions were drawn: At lower temperatures (25 °C and 100 °C), the coefficient of friction remains largely unaffected by variations in V content. However, when the test temperature reaches 600°C, the coefficient of friction initially decreases, then increases with rising V content. In general, the coefficient of friction decreases as the testing temperature increases. Comparative analysis of wear volume reveals that GCI with a V addition of 0.77 wt.% exhibits the best wear resistance at all three temperatures, with wear volume reductions of 75.29%, 79.14% and 75.17%, respectively. At lower temperatures (25 °C and 100 °C), the dominant wear mechanisms are fatigue wear and oxidative wear. When the temperature rises to 600 °C, the wear mechanism shifts to a combination of abrasive wear, fatigue wear, and oxidative wear. The addition of V to GCI contributes to the passivation of graphite tips, which suppresses crack initiation at graphite ends. Furthermore, the formation of vanadium carbides helps inhibit crack propagation, thereby reducing the overall wear volume. However, excessive addition of V (0.92 wt.%) weakens the passivation of graphite tips, resulting in increased crack formation and ultimately higher wear volume. In summary, these findings demonstrate that a V content of 0.77 wt.% is optimal for enhancing the wear resistance of GCI.