Structure evolution of pure titanium under different polishing conditions

Abstract

Pure titanium is a soft material. Its surface structure changes under different polishing conditions. In this work, mechanical polishing, chemical-mechanical polishing and electrochemical polishing pure titanium were performed to study the surface structure evolution. For mechanical polishing, it is hard to obtain scratch free surface using alumina fine particles as the abrasives. Chemical-mechanical polishing using 10% hydrogen peroxide can generate much more smooth surface. For the case of electrochemical polishing using fluorine ion-containing solutions after either mechanical or chemical-mechanical polishing, different surface features were observed depending on the electrochemical polishing parameters used. When the voltage was controlled lower than 10 V, the grain structure of Ti and etching pits were revealed. The material removal rate was calculated based on the data obtained from cyclic voltammetry tests. If the voltage was kept at 20 V, surface nanostructures including nanopores and nanotubes were found. The self-organised titanium oxide nanotubes were aligned vertically to the polished surface. Scanning electron microscopic analysis was carried out to reveal the surface structure evolution. In addition, elemental analysis using energy dispersive X-ray diffraction technique was conducted to show the composition of the surface nanostructures.