A novel method to mitigate residual stress in CVD diamond film on steel substrates with a single intermediate layer

Abstract

Direct deposition of CVD diamond on steel produces useless diamond film which delaminates on cooling from deposition temperature [1–9]. The majority of current research efforts focus on single and multiple intermediate layers for CVD diamond deposition on steel substrate. There are many excellent diffusional barriers to transition metals migration from bulk to substrate surface to form graphitic sp2 bonds. However, there is no practical solution to the thermal expansion coefficient (TEC) mismatch between diamond and steels. In this work we use a vanadium carbide thermodiffused coating as the intermediate layer between diamond and AISI O1 steel substrate. It acts as a diffusional barrier and mitigates diamond residual stress after cooling from CVD temperature. Increasing vanadium carbide layer thickness creates a transition zone that attenuates diamond residual stress. Up to now, the vanadium carbide is the only single layer barrier able to inhibit graphitic phase formation and mitigate residual stress in diamond films to the level of 0.54 GPa.