Exploring the effect of Ti doping on the friction characteristic of DLC films on the surface of pump plunger in petroleum extraction environments

DLC film is considered to be one of the most promising film materials for improving the abrasion resistance and operation life of pump plungers draw upon its low friction and high hardness, but the friction characteristics and mechanism of the doping element Ti on pump plungers under the petroleum extraction environment are still unclear. In this paper, the friction performance and mechanism of the doping Ti for DLC film on the appearance of the pump plunger under the petroleum extraction environment were investigated at the microscopic scale by using the reactive molecular dynamics. The outcome shows that the Ti-DLC displays a reduction in average friction force of 78.82 % and a decrease in average temperature of 40.33 % in the oil extraction environment, thus improving the abrasion resistance of the pump plunger. Moreover, with the increase of Ti content, the friction will gradually decrease, and significantly low friction behavior can be even materialized without lubrication. It is found that the main reason for the low friction of Ti-DLC film is that the layered structure determined by Ti concentration is formed on the appearance of friction pair, which inhibits the formation of interfacial carbon bond and reduces the shear stress on the contact surface.