High temperature diffusion chromizing as a successful method for CVD-diamond coating of steel

Using chromium carbide intermediate layers, generated by a novel diffusion process, well adherent CVD-diamond coatings were deposited onto large surfaces of 41Cr4 steel substrates. The chromium carbide intermediate layers feature excellent barrier properties against the diffusion of iron from the substrate and against the diffusion of carbon from the gas phase during the diamond deposition. The diamond coatings show also a very good adhesion. Only at a critical load of 150 N in the scratch test is the diamond coating stripped from the substrate. The measured Raman spectra prove a high diamond quality. The thickness of the adhesive diamond coatings can be increased through a tension-reduced structuring of the substrate surface.