2012 年 63 巻 8 号 p. 526-
In this study, a non-cyanide electropolishing solution was prepared for low-grade gold alloy containing palladium (Pd). Electropolishing conducted with an existing non-cyanide electropolishing solution prepared for 18-karat gold produced a rough and not mirror-finished 10-karat white gold (K10WG) surface. However, an electropolishing solution containing sodium sulfate and thiourea produced a smooth polished surface that exhibited some protrusions with a high Pd concentration. These protrusions decreased numerically when ethylene diamine tetraacetic acid tetrasodium (EDTA-4Na) was introduced into the sodium sulfate and thiourea solution to chelate noble metal such as Au and Pd. Electropolishing of K10WG using the solution containing thiourea, sodium sulfate, and EDTA-4Na produce a well-polished surface exhibiting high specular gloss.