Temperature influence on the interlayer and surface morphology of diamond coating on 3D porous titanium substrates

Nanocrystalline (NCD) and/or microcrystalline (MCD) diamond films grown on three-dimensional porous titanium (Ti) substrate were obtained by hot filament chemical vapor deposition (HFCVD) technique. The morphology variation of diamond films grown on porous three-dimensional titanium substrate was studied at four different deposition temperatures to investigate their influence on nucleation density. Scanning electron microscopy images depicted the continuous change from microcrystalline diamond grains with a random crystallographic orientation, at 500 °C and 600 °C, to a cauliflower-like structure for deposits at 700 °C and 800 °C. Visible Raman spectroscopy confirmed the good quality of diamond films and revealed that the amount of amorphous carbon increased associated to the film morphology changes from MCD to NCD. X-ray diffraction analyses, performed both through θ–2θ scans and at grazing incidence angle, allowed the investigation of the crystallographic properties and structural evolution of the different film/substrate interface phases, such as TiC(111), TiC(200) and TiH2. The results revealed that the temperature enhanced the nucleation sites for diamond growth.