Tribological behavior of a 20CrMo alloy implanted with nitrogen ions by plasma source ion implantation

A 20CrMo alloy was implanted with nitrogen ions using plasma source ion implantation (PSII), at a dose range of 1.0 × 1017 to 6.0 × 1017 ions cm−2. Electron Probe Micro-Analysis (EPMA) was used to investigate the depth profile of the implanted layer. Friction and wear tests were carried out on a multi-purpose wear tester. Scanning electron microscopy (SEM) was used to observe the micro-morphology of the worn surface. The results revealed that after being implanted with nitrogen ions, the friction coefficient of the surface layer decreased, and the wear resistance increased with the nitrogen dose. The tribological mechanism was mainly adhesive, and the adhesive wear tended to become weaker oxidative wear with the increase of the nitrogen dose. The effects were mainly attributed to the formation of a hard nitride precipitate and a supersaturated solid solution of nitrogen in the surface layer.