This study attempted to polish pure titanium test pieces electrolytically to mirror surface at the size of cast denture frames. Electrolytic polishing of pure titanium could be done on an area of 30 cm2 with a non-aqueous electrolyte. Small pure titanium plates could be polished electrolytically, but a uniformly smooth surface could not be obtained easily with large testpiece. The optimal electrolytic conditions were 30 V for 6 min at 25 degrees C using a solution consisting of 70 ml ethyl alcohol, 30 ml iso-propyl alcohol, 6 g aluminum chloride, and 25 g zinc chloride. The solution was safe and had less restriction of frequency of use.

A newly developed electropolishing system, equipped with an original agitation function for an electrolyte and using a safe electrolyte composed of an alcoholic solution, was applied for wrought and cast CP titanium and its alloys. Surface roughness and morphology of the polished surfaces were then examined. Under an electrolytic condition of 70-75 V, 2.0 kA/m2, and 30 degrees C, wrought CP Ti and Ti-6Al-4V alloy achieved an apparent mirror-like finishing with an average surface roughness (Ra) of 0.03 and 0.12 microm respectively. Under the same condition, on the other hand, cast CP Ti and Ti-6Al-7Nb alloy produced rougher polished surfaces with average Ra values of 0.67-0.80 microm, and the finishing was apparently shiny, but not mirror-like. SEM observation of the polished surfaces showed that wrought CP Ti was even and completely featureless, while wrought Ti-6Al-4V alloy was pitted. For cast CP Ti, a needle-like phase containing traces of iron was observed on the polished surface.

Study of pure titanium electrolytic polishing

Electropolishing of CP Titanium and Its Alloys in an Alcoholic Solution-based Electrolyte

Chemical mechanical polishing (CMP) of cpTi (Ti) was carried out using two types of slurries, acidic and basic colloidal silica containing H2O2 up to 3 wt%, to obtain flat and mirror-polished surfaces without any contaminated and reacted layers. Polishing behavior and surface properties were investigated using AFM, EPMA, and XPS. Weight loss of Ti polished by CMP using the basic slurry was larger than that using the acidic one, and surface roughness was less than 2 nm RMS when basic slurry containing 3 wt% H2O2 was used. Moreover, three kinds of chemical species, OH-, O2-, and H2O, were detected on the Ti surfaces polished by CMP using these slurries. Results of this study showed that CMP using colloidal silica containing H2O2 successfully created a mirror-polished surface without contaminated and reacted layers.

Chemical mechanical polishing of titanium with colloidal silica containing hydrogen peroxide--mirror polishing and surface properties.

Electrochemical buffing, a combined process of electrochemical and mechanical polishing, was applied to titanium casting. Mixture of alpha-Al2O3 suspension (average grain diameter of 5 microm) and 5% KNO3 solution was used as abrasive slurry. Specimen and experimental wheel buff were respectively connected to the positive and negative poles of a DC source, whose potential ratings ranged from 0 V (MEP) to 10 V (ECB10). Surface roughness, hardness, color, and cleanness were investigated. ECB10 surface produced a gold color and attained a mirror finish, as its roughness value was only one-quarter that of MEP. High amount of aluminum was present in MEP surface. Its bond state entirely differed from that of alpha-Al2O3, hence indicating surface alteration due to chemical reactions with the abrasive material. At higher potentials, reaction products might be dissolved anodically, so that the surface was chemically clean to some extent. The surface also became rich in OH-.

Study of pure titanium electrolytic polishing

Citations

Electropolishing of CP Titanium and Its Alloys in an Alcoholic Solution-based Electrolyte

Chemical mechanical polishing of titanium with colloidal silica containing hydrogen peroxide--mirror polishing and surface properties.

Surface properties of electrochemically buffed titanium casting.

Surface Characterization of Titanium Treated by Several Polishing Procedures Using X-ray Photoemission Spectroscopy

Development of dry‐nano‐polishing technique using reactive ion etching for ultra thin titanium wafer