彩色18K金首饰抗变色性研究

18K金首饰因其具有较高的硬度和丰富多彩的色泽,深受消费者喜爱。白色、黄色、红色是彩色18K金首饰常见的三种颜色,各选择一种具有代表性成分的18K金,采用紫外可见光谱仪、扫描电子显微镜、原子力显微镜研究和分析了三种常见彩色18K金耐盐雾、人工汗液、Na2S溶液的变色性。结果表明:三种彩色18K金显示了优异的耐盐雾和人工汗液变色能力,试验后肉眼未见变色;红色和白色18K金抗硫化变色的能力较强,黄色18K金抗硫化能力最差,表面变成棕色或者蓝色,变色区域覆盖了一层纳米级别的硫化产物。经分析,黄色18K金变色的主要原因是其含有高达13%的银元素,次要原因是铜元素。试验环境中的氧和温度亦是影响合金变色的因素,富氧和高温会加速合金变色。

Research on the discoloration resistance of colored 18 karat gold jewelry

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.