| Project/Area Number |
11671943
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
補綴理工系歯学
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| Research Institution | Health Sciences University of Hokkaido |
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Principal Investigator |
ENDO Kazuhiko Health Sciences University of Hokkaido School of Dentistry, Associate Professor, 歯学部, 助教授 (70168821)
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| Co-Investigator(Kenkyū-buntansha) |
OHNO Hiroki Health Sciences University of Hokkaido School of Dentistry, Professor, 歯学部, 教授 (70018430)
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| Project Period (FY) |
1999 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥3,900,000 (Direct Cost: ¥3,900,000)
Fiscal Year 2001: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2000: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1999: ¥2,900,000 (Direct Cost: ¥2,900,000)
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| Keywords | Ag-Pd-Cu-Au alloy / Corrosion resistance / Passivity / metal hypersensitivity / Castability / Vickers hardness / 腐食 / 硫化変色 / 動電位分極法 / X線光電子分光法 / 交流インピーダンス法 / 原子吸光法 |
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| Research Abstract |
The corrosion behaviors of eighteen Ag-Pd-Cu-Au alloys with different compositions were examined in 0.9 % NaCl and 0.1 % Na_2S solutions to develop a high corrosion resistant and biocompatible (allergy free) dental casting alloy. The effects of small amount of Ga on the castability, mechanical strength, and corrosion resistance of the Ag-Pd-Cu-Au alloy were also examined. The corrosion resistance was evaluated by electrochemical techniques and the analysis of released metal ions by atomic absorption spectrophotometry. The surface of the alloy was analyzed by X-ray photoelectron spectroscopy (IPS). The corrosion resistance of the Ag-Pd-Cu-Au alloy both in 0.9 % NaCl and 0. 1% Na2S solutions increased with an increase in Pd content. It was found that the Pd-25Ag-18Cu-12Au alloy with 45 mass% Pd was passive in 0.1 % Na_2S solution with the formation of Pd-rich sulfide film and did not tarnish unlike commercial Ag-Pd-Cu-Au alloys which tarnished with the formation of crystalline corrosion product of Ag_2S. The amount of released metal ions from the Pd-25Ag-18Cu-12Au alloy in 0.9 % NaCl solution was approximately 10 % of that from the commercial Ag-Pd-Cu-Au alloys. The addition of small amount of Ga (less than 5 mass%) lowed the liquids point of the Pd-25Ag-18Cu-12Au alloy and improved its castability without decreasing the resistance to corrosion and tarnish. The small amount of Ga also increased the value of Vickers hardness number. These results suggested that high level of resistance to corrosion and tarnish and excellent biocompatibility of the Pd-25Ag-18Cu-12Au alloy make this alloy suitable as a material for dental casting restoration.
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