| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2003: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 2002: ¥2,700,000 (Direct Cost: ¥2,700,000)
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| Research Abstract |
The aim of this study is to clarify composition of the alloys with more Au and less Pd than conventional Ag-Pd-Au-Cu alloys to secure corrosion resistance and safety and to come in practice. First, the test for sulfide corrosion resistance was carried out and estimated sulfide corrosion resistance of the alloys from the thickness of sulfide layer by XPS. Second, the jests for mechanical properties of the alloys were performed. The results were as follows:
1. Even if Pd content in the alloys was decreased, sulfide corrosion resistance was maintained or improved as Au content was increased.
2. Even if the contents of noble metals in the alloys were the same, the sulfide layer thickness tended to increase with Cu content. To confirm this forecast, the tests for corrosion resistance of the specimens which surface composition was changed by surface treatments including pickling, heating and polishing were conducted. As a result, the sulfide layer thickness of the alloys after solution heat treatment and polishing, with high Cu content, was thicker than that of after pickling, with low Cu content. Cu content was related to sulfuration of the alloys.
3. It was revealed that even the alloys which Cu content was reduced to improve the corrosion resistance had mechanical strength corresponding to conventional Ag-Pd-Au-Cu alloys.
From these results, sulfide corrosion resistance and mechanical properties of the Ag-Pd-Au-Cu alloys with more Au and less Pd proved to be not inferior to conventional alloys.
In future, assuming that prosthesis exists in oral cavity for a long time, biological evaluation of the alloys in consideration of allergy due to dissolution ions will be carried out and the potential for practical alloy will be estimated.
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