A novel approach of chemical mechanical polishing for a titanium alloy using an environment-friendly slurry

In this study, a novel approach of CMP is developed using an environment-friendly slurry consisting of silica, hydrogen peroxide (H2O2), malic acid and deionized water. This is different from the traditional polishing, in which hazardous chemicals are used for Ti alloys. The surface roughness Ra of 0.68 nm is obtained over a measurement area of 70 × 53 μm2, which is lower than those previously reported for a Ti alloy. This is polished by the developed optimal CMP slurry. Polishing mechanism is investigated using electrochemical and X-ray photoelectron (XPS) measurements. H2O2 dominates the corrosion process during CMP using the developed environment-friendly slurry. Corrosion current of H2O2 is consistent with the reactants of titania, alumina and vanadia formed on the surfaces of Ti-6Al-4 V after CMP. Corrosion potential agrees well with the polished surface quality of Ti-6Al-4 V. Chemical reaction equations are proposed according to the electrochemical and XPS measurements. The developed CMP slurry sheds light on the application in environment protection for the Ti, Ti alloys and CMP industries.