Effects of Ion Implantation Conditions on the Tribology of Ferrous Surfaces

Abstract

The effects of implanted nitrogen ion dose and target surface temperature during implantation on the wear characteristics of iron (ferrite) and 304 stainless steel (austenite) have been studied systematically. Wear test results obtained using an oscillating pin-on-disk tester show that high dose rate, high dose implantation into these materials when they are being held at an elevated temperature (near 400°C) induce dramatic improvements in their wear characteristics. Surface and near-surface analysis techniques are used to demonstrate that implanted ion dose and surface temperature can be controlled to produce a desired microstructural state and thickness of the nitrogen-implanted layer. The most wear resistant surfaces are produced when γ’-Fe4 N is formed in the ferrite and a concentrated solid solution of nitrogen is produced in the austenite. Implanted layer thicknesses greater than ~ 1 μm (an order of magnitude beyond the ballistic implantation depth) are observed in the austenite.