High-Efficiency Chemical Mechanical Polishing of Ti-6Al-4V Alloy via the Synergistic Action of H2O2 and K+ Under Alkaline Conditions

Abstract

Ti-6Al-4V (TC4) alloy has been widely used for implants, and excellent surface quality is required for satisfactory performance. In this study, chemical mechanical polishing (CMP) was introduced to process TC4 alloy. H2O2 and K+ were used to enhance the CMP efficiency. It is revealed that, at pH 10, the material removal rate (MRR) of TC4 alloy increases with the increasing H2O2. A synergistic action between H2O2 and K+ exists under alkaline conditions. With H2O2 and at pH 10, as the K+ concentration increases, the MRR of TC4 alloy first increases and then levels off. The anions have little influence on the CMP performance. After polishing, the surface is smooth without scratches, and the substrate underneath the surface film has no processing damage. For the synergistic action, K+ ions are adsorbed on the Stern layer of the TC4 alloy surface and the silica particles, screening the surface negative charge. Firstly, OOH− produced from H2O2 and OH− can approach the TC4 alloy surface easily, promoting the corrosion. Secondly, more silica particles come into contact with the TC4 alloy surface, enhancing the interactions. Therefore, the MRR increases. The research work brings about a promising high-efficiency CMP process for titanium alloys.