Effect of temperatures up to 400 °C on the impact-sliding of valve-seat contacts

After their introduction by Godet and co-workers, the concept of the third body has been extensively applied to understand the effect of interfacial films arising between sliding bodies, and the effect of oxides is a key factor to explain the friction and wear under oxidative environments. Most of oxides remain into the contact as a protective layer governing the tribological behavior of metallic surfaces. In many industrial applications, and especially in transports, the machinery and equipment are often subjected to combined attacks of impact and sliding leading then to surface damage. An application where these effects are determinant is the valve-seat contact of internal combustion engines, especially the new generation of diesel engines due to very high pressures. The surface of the seat is subjected to repetitive impact actions of the valve, with small amplitude sliding in the interface. Investigating effects of the behavior of materials used in the present under the action of impact-sliding under temperatures up to 400 °C would help to gain better understanding of the failure mechanisms and to establish the guidelines for future improvements, namely concerning surface treatments. The present research was carried out to study the combined aspects of impact and sliding wear.