| 18K gold jewelry is deeply loved by consumers due to its high hardness and rich and colorful colors. White, yellow and red are three common kinds of 18K gold jewelry. One representative component of each 18K gold was selected, and the resistance to salt mist, artificial sweat, and Na2S solutions discoloration of three kinds of 18K gold were studied and analyzed by ultraviolet visible spectrometer, scanning electron microscope and atomic force microscope. The results showed that the three kinds of 18K gold showed excellent resistance to salt mist and artificial sweat discoloration, and no discoloration was observed by the naked eye after the test. Red and white 18K gold have strong resistance to sulfide discoloration. After the sulfurization experiment, the surface of yellow 18K gold turns brown or blue which is covered with a layer of nanoscale corrosion products, and the sulfurization resistance is the worst. According to the analysis, the main reason for the discoloration of yellow 18-karat gold is that it contains up to 13% silver element, the secondary reason is copper element. Oxygen and temperature in the test environment are also factors affecting the alloy discoloration. Oxygen enrichment and high temperature will accelerate alloy discoloration. |
