CVD diamond coating of steel on a CVD-TiBN interlayer

Adherent and homogeneous diamond films were deposited on 41Cr4 steel substrates employing chemical vapor deposited (CVD) TiBN interlayers. The suitability of CVD-TiBN interlayers for diamond deposition was investigated. The CVD intermediate layers showed excellent barrier properties against the diffusion of iron from the bulk substrate to the surface and against diffusion of carbon from gas phase during diamond deposition. Various growth conditions for interlayers affect their thickness and composition. For these samples different shares in the phases TiB2 and TiN were analyzed by XRD. The diamond coating onto the TiBN interlayer showed very good adhesion. The measured Raman spectra proved high compressive stresses in the diamond film with a high diamond quality. Sandblasting tests indicated an enormous improvement of the erosion resistance after diamond deposition on 41Cr4 substrates with a 5 μm intermediate layer of TiBN.