Diamond Thin Film Coating on WC Substrate by HFCVD Method using Different Seeding Powders and Its Characterization

The formation of diamond thin solid film is studied by Hot Filament Chemical Vapor Deposition (HFCVD) by using different seeding powders on WC substrate. Here, we have deposited microcrystalline diamond (MCD) on SPUN cemented carbide (WC-Co) cutting tool insert using conventional HFCVD technique. The substrates were ultrasonically seeded with titanium, tungsten, molybdenum, diamond, combined diamond and tungsten powder at the same operation parameters to observe the difference in the growth of diamond by different seeding. Nucleation of diamond coating was studied after 40 minutes of coating with seeded substrate. The physical characteristics were studied by X-ray Diffraction (XRD).The Scanning Electron Microscope (SEM) was used to study the surface morphology. The diamond purity was studied with the help of Raman spectroscopy (RS). Reduction of cobalt percentage before and after pretreatment was studied by Energy Dispersive Spectroscopy (EDS). A very dense and uniform coating was deposited on the diamond powder seeded substrate. The nucleation density was found to be highest in diamond powder when compared with molybdenum and tungsten powder individually, because in initial stage the deposited material contains more sp2 content as compared to sp3 content. By using diamond and tungsten mixed powder the coating was uniform rather in case of only tungsten powder coating the discrete crystals were formed.