Effects of pH Values and H₂O₂ Concentrations on the Chemical Enhanced Shear Dilatancy Polishing of Tungsten

In order to obtain tungsten with great surface qualities and high polishing efficiency, a novel method of chemical enhanced shear dilatancy polishing (C-SDP) was proposed. The effects of pH values and H₂O₂ concentrations on the polishing performance of tungsten C-SDP were studied. In addition, the corrosion behaviors of tungsten in solutions with different pH values and H₂O₂ concentrations were analyzed by electrochemical experiments, and the valence states of elements on the tungsten surface were analyzed by XPS. The results showed that both pH values and H₂O₂ concentrations had significant effects on tungsten C-SDP. With the pH values increasing from 7 to 12, the MRR increased from 6.69 µm/h to 13.67 µm/h. The optimal surface quality was obtained at pH = 9, the surface roughness (R_a) reached 2.35 nm, and the corresponding MRR was 9.71 µm/h. The MRR increased from 9.71 µm/h to 34.95 µm/h with the H₂O₂ concentrations increasing from 0 to 2 vol.%. When the concentration of H₂O₂ was 1 vol.%, the R_a of tungsten reached the lowest value, which was 1.87 nm, and the MRR was 26.46 µm/h. This reveals that C-SDP technology is a novel ultra-precision machining method that can achieve great surface qualities and polishing efficiency of tungsten.