The Research On Corrosion Behavior Of Bronze Covered With Patina By Typical Organic Acid Gases

Bronze artifacts are valuable historical wealth,it is an important reference for the research of human culture,history and metal smelting and so on.In the collection of cultural relics protection environment,decoration materials and other reasons caused release of volatile organic acid gaseous pollutants have a great threat to the collection of cultural relics,so in order to achieve preventive protection,the research on corrosion behavior and regularity of bronze relics by typical organic acid gas have important significance.According to the characteristics of the rust layer on the surface of bronze artifacts,in this paper,three kinds of patinated bronze were prepared by electrochemical method.The corrosion process of bare bronze and patinated bronze materials in organic acid gas environment was studied.The morphology and composition of corrosion products were characterized by SEM,XRD and Raman.Electrochemical corrosion behavior in different concentrations of organic acid solution were investigated.The corrosion behavior of different patinated bronze materials in organic acid solution was analyzed and the corrosion difference between different patinated bronze was compared.Exposed accelerated corrosion experiment results show that:bronze corrosion is copper-rich priority corrosion.And patinated bronze in the organic acid corrosive performance:formic acid>acetic acid.In the formic acid gas,the final corrosion products of bare bronze and Cu2O patina bronze are cuprous oxide and light blue copper formate crystals,and mixed with rust bronze in the formic acid atmosphere,the corrosion of the rust layer is carried out at the same time,the corrosion products are newly formed copper chloride hydroxide,copper formate and pale blue copper formate crystals.In acetic acid gas,the final corrosion products of bare bronze and Cu2O rust bronze are cuprous oxide and light blue copper acetate crystals.There are three kinds of rust layers on the surface of the mixed patina bronze,which are protective to the bronze matrix.However,the corrosion of the rust layer is carried out at the same time.In addition to the relatively stable copper chloride hydroxide,the other corrosion products are copper acetate hydroxide and copper acetate crystals.And with CuCl patinated bronze will react with the water and oxygen in the air to produce green powder rust alkaline copper chloride,and the acidic environment will accelerate the process.The results show that the Rp of the rusted bronze decreases with the increase of the concentration of organic acid solution,which indicates that the corrosion rate increases with the concentration of the organic acid solution,and the corrosion rate in the formic acid solution significantly larger than acetic acid solution,probably because formic acid is more likely to ionize out of H+ than acetic acid in aqueous solution.The results show that the Icorr of four patinated bronze enlarges with the increase of the concentration in the organic acid solution,and the Icorr in the formic acid solution is larger than that in the acetic acid solution.Simultaneously,in the 100mg/L formic acid solution,the Icorr of CuCl patina bronze was the largest,while in the 100mg/L acetic acid solution,the Icorr of mixed pantina bronze was the largest,and the greater the corrosion current density,the more serious the corrosion.