PURPOSE: The aim of this research was to obtain an objective grasp of the surface properties of titanium castings which are polished using a titanium polishing method developed by our university. METHODS: The specimens were cast conventionally using commercially pure (CP) titanium (Grade 3, T-alloy H, GC). The cast surfaces were polished using two methods; a conventional procedure for mirror surfaces and a modified procedure consisting of minimal grinding foracceptable fit of the inner surface. The center line average roughness (Ra) wasmeasured, and then qualitative analysis and map analysis were performed using Electron Probe X-ray Microanalysis. In addition, map and line analysis on sections of the as-cast titanium specimens was performed, and the Vickers hardness of the surface was measured. As controls, Au-Pt alloy and Co-Cr alloy specimens were analyzed. RESULTS: The Ra on the titanium inner surface was 1.52 microm, which was approximately four times higher than that on the mirror surface, and approximately two times higher than that for the Au-Pt alloy and Co-Cr alloy. The qualitative analysis of the titanium mirror surface detected elements such as C, Si, and Al as well as the ingot element. In addition, P was also detected on the titanium inner surface. The Vickers hardness was highest on the outermost surface layer, which decreased remarkably until a depth of 100-150 microm. CONCLUSIONS: It was considered that the mirror surface formed by the titanium polishing method in our university obtained a level equivalent to that of precious metals. However, a reaction layer and elements derived from the investment material remained in the titanium inner surface.
[Analysis of polished surfaces of titanium castings.] Publishing Authors By Initials
