Diamond deposition on copper treated hardmetal substrates

The adhesion of diamond coatings onto hardmetal substrates is improved by a copper deposition produced by a cementation from aqueous CuSO₄ solutions. During this reaction Co is dissolved from the substrate surface and copper is deposited. To obtain homogeneous Cu deposits, the influence of CuSO₄ concentration and reaction time on cementation were investigated.

During diamond deposition, Cu reduces the surface mobility of Co, which is necessary to decrease deposition of non-diamond carbon and therefore increase adhesion. Indentation tests showed the good adhesion of the diamond coatings qualitatively.

Cu precipitation and diamond deposition were examined by scanning electron microscopy (SEM). The diamond quality was detected by Raman spectroscopy. Using secondary ion mass spectroscopy (SIMS) depth profiles the interface and the Cu distribution were characterized indicating that during diamond deposition Cu is dissolved and forms an intermetallic Co-Cu mixed crystal.