Homogeneous micro and nanocrystalline diamond coating on reticulated vitreous carbon treated at different temperatures

Abstract

Diamond film grown on reticulated vitreous carbon (RVC), as a three dimensional composite, was investigated. RVC substrates were obtained at three different heat treatment temperatures (HTT) which promoted different structural organization indexes on their turbostratic carbon (TC) structure. Homogeneous microcrystalline (MCD) and nanocrystalline (NCD) diamond grains were formed and showed that are strongly affected by the substrate HTT. Particularly, the changes in diamond films properties were discussed as a function of the film nucleation and morphology evolution for growth times of 1 and 3 h. Scanning electron microscopy images confirmed the continuous films with high nucleation rate, including on RVC struts edges which actuality demand higher film growth rate. The high nucleation rate, typical of NCD formation in the first stage of film growth, was mainly attributed to the different graphitization indexes of such carbon substrates which were etched by atomic hydrogen on RVC prism or basal planes. Micro-Raman spectra also confirmed the features of NCD coating. The high contribution of NCD population in diamond Raman peak at 1332 cm − 1 promoted its asymmetry with some tailing towards lower wavelength shifts, better observed for diamond grown on RVC treated at 1300 K.