Micromachining of ferrous metal with an ion implanted diamond cutting tool

Abstract Diamond is a highly favorable material for cutting tools, particularly in ultra-precision machining to produce highly accurate freeform surfaces with mirror-like finishing. Unfortunately, diamond cutting tools undergo catastrophic wear when machining transition metals such as iron, cobalt, nickel, etc. The underlying wear mechanism is understood to involve dissociation of carbon atoms from the diamond lattice, i.e. graphitization. Existing approaches of wear reduction aim at reducing chemical reactivity generally through process modifications. In this work, the effectiveness of ion implantation as a tool modification methodology is studied on the gallium ion irradiated diamond tools. Wear occurrences are compared between irradiated diamond and unmodified diamond using thermal analytical techniques and micromachining experiments. Calorimetric tests showed a 44% increase in activation energy required for graphitization with a Ga ion dose of 1×10 13 ions/cm 2 at 30 keV. Significant improvements in the wear resistance of an irradiated diamond tool are also observed in micromachining tests with the reduction in workpiece adhesion that indicates potentially lower heat generation at the tool-chip interface for the graphitization process. Ab initio calculations suggest an increased stability against exfoliation with the reduction in surface energy, which influences the surface-to-surface interaction between the diamond and catalytic iron.