Effects of Addition of Indium and/or Gold on Corrosion Resistance and Tarnish Resistance of Silver-Palladium Alloys

将9种银钯合金（Ag+Au=58%, Pd=20%, Cu+In=18%, Zn=4%）分别置于0.1% Na_2S溶液和1% NaCL溶液中，分别进行了无光试验、电化学腐蚀试验和质量损失试验。通过对实验范围内合金的研究，可以得出以下结论：1. 当不加铜而加铟时，合金的颜色比含铜合金的颜色更深，颜色更浓，颜色更红，即无论含金量如何，合金的颜色都比含铜合金的颜色更深，颜色更浓，颜色更红，在一定程度上呈现出类似黄金的外观。在铟含量不变的情况下，金含量的增加对合金颜色的影响不明显。2. 合金在氯化钠溶液中耐污性好，在硫化钠溶液中耐污性差。在铟含量相同的情况下，金含量的增加会增加合金的抗污性。如果合金中铟和铜的含量相等，那么与只含铟或铜的合金相比，抗污性显著降低。后一种效应非常显著，38%Ag-20%Au-20%Pd-9%Cu-9%In-4%Zn合金的耐污性不如58%Ag-20%Pd-18% (Cu或In) -4%Zn合金。3.合金在硫化钠溶液中比在氯化钠溶液中更容易腐蚀。在铟含量相同的情况下，随着金含量的增加，合金的耐蚀性显著提高。如果合金中铟和铜的含量相等，则合金的耐腐蚀性比只含铟或铜的合金低。4.在氯化钠溶液中，耐蚀性与耐污性呈正相关。

Nine silver-palladium alloys (Ag+Au=58%, Pd=20%, Cu+In=18%, and Zn=4%) with three levels of indium content (0,9, or 18%) and three levels of gold content (0,10, or 20%) were characterized by tarnish test, electrochemical corrosion test, and mass loss test immersed in 0.1% Na_2S solution as well as in 1% NaCL solution. The following conclusions may be derived from this investigation about the alloys within the experimental range. 1. The color of alloy becomes darker, more chromatic, and more reddish, i.e., gold-like appearance to some extent regardless of gold content compared to the copper containing alloy when indium is added instead of copper. Increasing of gold content does not change the color of alloy very remarkably as long as indium content is the same. 2. The tarnish resistance of alloy is good in the sodium chloride solution, while it is poor in the sodium sulfide solution. Increasing of gold content increases the tarnish resistance of alloy as long as indium content is the same. If the alloy contains indium and copper equally, the tarnish resistance decreases dramatically compared to the alloy which contains either indium or copper. The latter effect is so remarkable that the tarnish resistance of 38%Ag-20%Au-20%Pd-9%Cu-9%In-4%Zn alloy is inferior to that of 58%Ag-20%Pd-18% (Cu or In) -4%Zn alloy. 3.The alloy appears to be corrosion prone in the sodium sulfide solution rather than in the sodium chloride solution. Increasing of gold content increases the corrosion resistance of alloy remarkably as long as indium content is the same. If the alloy contains indium and copper equally, the corrosion resistance decreases compared to the alloy which contains either indium or copper. 4.There is a positive correlation between the corrosion resistance and the tarnish resistance in the sodium chloride solution.