Fabrication Of Inlay Structure Diamond Films On Fe Substrate And The Evaluation Of Adhesive Strength

Diamond film has wide application prospect in mechanical processing area because of itsExcellent physical、chemical、mechanics and thermal properties. Although diamond filmdeposited on steel can improve the life and performance, it is difficult to deposit diamond filmdirectly onto steel substrate due to theas the iron on Fe/diamond interface catalysing diamondinto graphite. Pre-depositing an interlayer was considered necessary for the depositiondiamond films on steel substrate.An inlay structured interlayer was designed to deposit diamond film on steel in thisthesis. The inlay structured interlayer was fabricated by using a two-step process. The firststep was to sputtering a Cr/Cu coating as a diffusion barrier layer, and the second step was tocomposite plating a Cu-diamond coating as inlay structured interlayer. At last, the diamondfilm was deposited on the top of inlay structured interlayer using the hot-filament chemicalvapor deposition (HFCVD) method.Interface Cohesion of Cr/Cu coating on steel was studied firstly in this thesis. The Cr/Cucoating were deposited using two way, and heat treatment experiment indicated the Cr/Cucoating deposited by magnetron sputtering was better than by electroplating.To deposit an adherent diamond film on steel, a4.2μm-thickness-Cr coating was need toblock the diffusion Fe and C. Diffusion and interface reaction of Fe, C, Cu, and Cr afterdepositing diamond films were studied. Section morphology and EDS data shows Cr7C3coating was formed and Fe was blocked effectively by Cr coating and Cr7C3.After preparing diamond film, the effect of CVD processes on diamond film werestudied. Nine samples were prepared under different power、 pressure and methaneconcentration. The samples were characterized by scanning electron micros-copy (SEM),Raman spectroscopy and XRD, to examine the surface morphology, crystallinity and residualstress, and phase structure, respectively. The result showed, the diamond has battercomprehensive performance deposited when filament power is450W, pressure is4.5kPa andCH4concentration is1.0%.In the final chapter, the effect of different size of inlayed diamond particle on film adhesion was studied. Three samples were prepared with3.5μm,5μm and10μm inlayed ininterlayer. The indentation test showed the sample with10μm inlayed in interlayer has thebest adhesion.