Growth Features of Diamond Films on the Tungsten Carbide Surface with a Copper Sublayer

The surface preparation is a prerequisite for ensuring the required properties of a diamond film formed by gas-phase deposition. The influence of the temperature and concentration of the CuSO 4 etchant on the structural and phase compositions of the surface of hard-alloy materials is considered in this work, and the structural and phase compositions of a continuous polycrystalline diamond film at its growth stages is also considered. The adhesion of the diamond films to the surface of hard-alloy materials is determined qualitatively. It is established that the treatment of the hard-alloy surface in the CuSO 4 solution at t = 23°C leads to the inhomogeneous removal of a cobalt binder with chipping WC grains and the formation of the porous structure in the surface layer of the WC–6% Co alloy. The treatment by the CuSO 4 etchant at t = –2°C provides the homogeneous etching of the Co binder over the boundaries of WC grains and the formation of a chemically homogeneous surface. The orientation growth and adhesion of the diamond film depend on the elemental composition of the WC–Co alloy surface after treatment by the CuSO 4 solution. If the treatment was performed at t sln = 23°C, then the removal of copper from the defect surface WC layer is complicated during the synthesis, which provides the multidirectional growth of diamond crystals in the film along two directions, 〈111〉 and 〈110〉, which causes critical biaxial compressive stresses (2.5 GPa) and leads to low film adhesion to the hard alloy surface. If the treatment is performed at t sln = –2°C, then the orientational growth of diamond crystals in the film occurs in one preferential crystallographic direction 〈111〉, which lowers the biaxial compressive stresses (1.7 GPa) and increases the adhesive bond of the film to the hard alloy surface. The structure imperfection calculated from the ratio of the lines of integrated intensities I 1333 / I 1580 using the Raman spectroscopy method decreases with an increase in concentration at negative temperatures and increases at positive temperatures of the CuSO 4 solution during surface preparation.