F.L. Zhang

Effect of Electrical Spark Discharging Parameters on the Etching of Chemical Vapor Deposition (CVD) Diamond Film

In this article electrical spark discharging was used to etch the diamond film synthesized by chemical vapor deposition (CVD) in order to obtain flatten and smooth surface. The effects of parameters in electrical spark discharging such as the pulse width, electrode shape, metal layer thickness, and the polarity on diamond removal height were investigated. The etched surface of diamond film was examined by scanning electron microscopy (SEM), Raman spectrum analysis. It was found that higher peak current, pulse width of 400 μs, smaller electrode cross section, thinner metal layer, and negative polarity of the diamond film could benefit the material removal process. An etching mechanism model was also proposed that the material removal of diamond is the compound effects of vaporization, graphitization, cleavage fracture, oxidation of diamond in the electrical spark discharging.

Brazing of diamond grits with Ag-Cu-Zn alloy activated by Cr or Ti powder under different environments

In this study, Ag-Cu-Zn brazing alloy together with Cr or Ti powder had been used to braze diamond grits under different environments, such as: air, vacuum, argon gas protection, salt covering and carbon powder covering. The microstructure on the interfaces of diamond grits, brazing alloy and steel substrate was examined by Scanning Electron Microscopy (SEM) and optical microscopy. The results showed that by adding Cr powder, the diamond grits could be brazed onto the steel substrate in air and owned enough bonding strength and wear resistance when grinding granite. By adding Ti powder, the diamonds could be well brazed in vacuum or in the air with the protection of carbon powder. In brazing, the migration of Cr or Ti element to the surface of diamond and the forming of Cr or Ti rich area had significantly improved the wettability of the brazing alloy to the diamond grits.