A New Metallographic Etchant of High Purity Gold

In order to observe the microstructure of high purity gold, the metallographic samples were often corroded by aqua regia, which had many problems such as strong environmental pollution and great potential safety hazard. Aqua regia and the mixed aqueous solutions of ferric chloride and hydrogen peroxide were used to corrode the high purity gold, and the results were compared and analyzed. The results show that the two kinds of etchants, aqua regia and ferric chloride hydrogen peroxide mixture solution, could corrode the high purity gold, and it was more environmentally friendly and safe to use ferric chloride hydrogen peroxide mixture solution. The corrosion effect of the mixed solution of ferric chloride and hydrogen peroxide was better than that of aqua regia, and the microstructure of sample after corrosion more clearly and without oxide film. The key to the corrosion of high purity gold was the presence of oxidants and ions which could form soluble complexes with gold.