Ion Implantation is a common technique for improving the surface properties of tribological materials, but characterization of implanted materials is made difficult by the fact that the properties vary with depth from the surface. Ion species are implanted with ranges on the order of 100 nm, so property changes must be sensed with depth resolutions of tens of nms. In reality, most characterization techniques provide depth resolution on the order of the ion range, so some care must be taken to extract the local material properties from tests that necessarily sample the substrate properties as well. In this paper, finite element simulations are compared to hardness tests and wear tests to show the relationship between property changes (particularly the yield stress), hardness distributions, and wear rates measured with a pin-on-disk wear tester.
Several prev studies have used finite element simulations to help correlate data from hardness tests. Early works [2][1] focused on the simulation of indentation using spherical indenters, but later works [5][4][3] have studied conical indenters to better simulate indentation by the non-axisymmetric indenters used in all hardness tests. More recently, finite elements have been used to study non-homogeneous materials, such as coatings [7][6] and ion implanted surfaces [10][9][8]. These works inspired the present study, which involves, in part, the simulation of hardness tests in ion-implanted materials. In particular, the works of Bourcier, et al. are the first to attempt to estimate the property changes induced by ion implantation using a combination of finite element simulation and hardness testing. The present study adopts this methodology and extends it to assess the relationship between the yield stress changes and the wear rate.