Corso P P, German R M, Simmons H D
J Dent Res. 1985 May;64(5):848-53. doi: 10.1177/00220345850640051301.
Three commercial gold dental alloys and three ternary (Au-Ag-Cu) alloys of constant nobility were subjected to a standardized test battery for tarnish. The tests included sodium sulfide and artificial saliva solutions, both at 37 degrees C, in sealed containers. Quantitative measurements of tarnish were made from the alloy color change during a three-day exposure. Alloy nobility is a relatively important factor in determining tarnish resistance; however, microstructure can have a negative effect on tarnish resistance. Alloys with a two-phase microstructure produce microgalvanic conditions which lead to either silver chloride or silver sulfide tarnish products. A solution heat treatment improves tarnish resistance by eliminating microstructural inhomogeneities.
三种商用金牙科合金和三种具有恒定贵金属含量的三元（金-银-铜）合金接受了标准化的变色测试。测试包括在37摄氏度的密封容器中使用硫化钠溶液和人工唾液溶液。在三天的暴露过程中，通过合金颜色变化对变色进行了定量测量。合金的贵金属含量是决定抗变色性的一个相对重要的因素；然而，微观结构可能会对抗变色性产生负面影响。具有两相微观结构的合金会产生微电池效应，导致形成氯化银或硫化银变色产物。固溶热处理通过消除微观结构的不均匀性来提高抗变色性。
