Development of Corrosion resistant dental Ag-based alloys with low Pd and Cu content.

为研制低Pd含量的高耐蚀牙科铸造合金，研究了25种Ag-Pd-Cu-Au合金和5种Ag-In-Au合金在0.9%NaC l和0.1%Na2S溶液中的腐蚀行为。采用电化学方法和原子吸收光谱分析技术对涂层的耐蚀性进行了评价。用X射线光电子能谱(XPS)对合金表面进行了分析，发现在模拟口腔环境中，要保持足够的耐蚀性能，需要加入质量分数为15%的Pd。Ag-15Pd-15Au-(10-20)Cu合金可以替代目前用于镶嵌、冠和桥的Ag-20Pd-(10-20)Cu-12Au合金。对于Ag-In-Au合金系统，少量的Au(1-3质量%)可以显著提高Ag-20In合金在0.9%NaC l和0.1%Na_2S溶液中的耐蚀性。Ag-20In-(1-3)Au合金可用作高耐蚀性的无Pd牙科铸造合金。这些合金适用于镶嵌和牙冠。

The corrosion behaviors of twenty five experimental Ag-Pd-Cu-Au alloys and five Ag-In-Au alloys were examined in 0.9% NaCl and 0.1% Na_2S solutions to develop a high corrosion resistant dental casting alloy with low Pd content. 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 (XPS).It was found that the 15 mass % of Pd was required for the Ag-Pd-Cu-Au alloys to maintain sufficient corrosion resistance in simulated oral environments. The Ag-15Pd-15Au-(10-20)Cu alloys can be alternatives to the Ag-20Pd-(10-20)Cu-12Au alloy that is currently used for inlays, crowns and bridges.For Ag-In-Au alloy system, small amount of Au (1-3 mass%) drastically improve corrosion resistance of the Ag-20In alloy both in 0.9% NaCl solution and 0.1% Na_2S solution. The Ag-20In-(1-3)Au alloy is can be used as a Pd-free dental casting alloy that possesses high corrosion resistance. These alloys are suitable for inlays and crowns.