Effect of N ion implantation on tribological properties of spring steels

D6A and C75S spring steels were implanted by nitrogen ions at an energy of 65 keV and a fluence of 6 x 10(17) ions/cm(2). The hardness and tribological properties of implanted samples were studied. In a reciprocating ball-onplate wear test, a relatively low contact pressure was applied (9 mm diameter ball under load up to 0.5 N) In the implanted samples two stages of wear process can be distinguished. In the first stage a low friction coefficient and low wear rate are observed while in the second stage their values considerably increase. The duration of the first stage depends on the applied load (contact pressure). At low contact pressure, the wear life can be extended considerably, and at high contact pressure the first stage practically disappears and the effect of ion implantation is negligible. The evolution of wear process in the second stage is similar to that of nonimplanted sample. Analysis of morphology and chemical composition of wear tracks with SEM reveals different mechanisms at different stages of wear in implanted samples wear. At the first stage, adhesive and abrasive wear predominate, while in the second stage, oxidative and fatigue mechanisms occur that are similar to those observed for a nonimplanted material.

Automated summary

The hardness and tribological properties of D6A and C75S spring steels implanted with nitrogen ions were studied. It was found that the implanted samples went through two stages of wear process, with low friction coefficient and wear rate in the first stage, and considerably increased values in the second stage. The duration of the first stage depended on the applied load, with extended wear life at low contact pressure.