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Development of Highly Corrosion Resistant Ag-Pd-Cu-Au Casting Alloy

高耐蚀Ag-Pd-Cu-Au铸造合金的研制

基本信息

批准号：
08557106
负责人：
MATSUDA Koich
金额：
$ 2.88万
依托单位：
Health Sciences University of Hokkaido
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

项目摘要

To develop a highly corrosion resistant Ag-Pd-Cu-Au alloy, the corrosion and tarnish behaviors of an experimental Ag-Pd-Cu-Au alloy with 45 mass % Pd were addressed in 0.1% Na2.S and 0.1% NaCI solutions. Corrosion and tarnish resistance of Ag-45Pd-l8Cu-l2Au alloy was evaluated in relation to the microstructure after various heat treatments by potentiodynaniic polarization and spectrocolorinietric measurements. The alloy surface after immersion in 0.1% Na2S solution was examined by X-ray photoelectron spectroscopy (XPS).This alloy has Pd-rich single-phase structure and the segregation observed in as-cast alloy did not markedly affect the corrosion behavior. The potentiodynamic polarization and the spectrocolorimetric measurements demonstrated that this alloy was highly corrosion resistant and practically free of corrosion in 0.1% Na_2S solution. This extremely high corrosion and tarnish resistance was due to passivity attained by the formation of Pd-rich sulphide film that was identified by XPS.The amounts of metallic ions released into 0.9% NaCI solution from the Ag-45Pd-l8Cu-l2Au alloy were much lower than those from a commercial Ag-2OPd-l8Cu-l2Au alloy.The addition of small amount of Ga effectively lowered the melting point and improved the castability of the experimental alloy. Small amount of Ga (1-5 mass %) did not decrease the corrosion resistance of the alloy.The characteristics of the experimental Ag-45Pd-l8Cu-l2Au alloy such as high corrosion resistance, excellent tarnish resistance, and good castability are suitable for dental casting restorations used in the oral environment.

为了开发一种高耐蚀性的Ag-Pd-Cu-Au合金，研究了含45%（质量分数）Pd的Ag-Pd-Cu-Au合金在0.1%Na2.S和0.1%NaCl溶液中的腐蚀和失泽行为。本文用动电位极化法和分光光度法研究了Ag-45 Pd-18 Cu-12 Au合金的耐蚀性和抗变色性与不同热处理后显微组织的关系。用X射线光电子能谱（XPS）对合金在0.1%Na2S溶液中浸泡后的表面进行了分析，结果表明，该合金为富Pd单相结构，铸态合金中的偏析对腐蚀行为没有明显影响。动电位极化曲线和分光光度法测定结果表明，该合金具有良好的耐蚀性，在0.1%Na_2S溶液中几乎无腐蚀。这种极高的耐腐蚀性和失泽性是由于通过XPS鉴定的富Pd硫化物膜的形成而获得的钝化性。从Ag-45 Pd-18 Cu-12 Au合金释放到0.9%NaCl溶液中的金属离子的量远低于从商业Ag-2 OPd-18 Cu-12 Au合金释放到0.9%NaCl溶液中的金属离子的量。l2 Au合金中加入少量Ga，有效地降低了合金的熔点，改善了合金的铸造性能。少量Ga（1-5 mass %）的加入并不降低合金的耐蚀性，所制备的Ag-45 Pd-18 Cu-12 Au合金具有耐蚀性高、抗失泽性好、可铸性好等特点，适合于口腔环境下的牙科铸造修复。