臭氧浓度变化对馆藏银器文物腐蚀变色的影响

The effect of ozone concentration and of humidity on tarnishing of antique silver in museums

博物馆环境中的臭氧作为氧化剂,对文物起到氧化腐蚀的作用,会使馆藏银器文物腐蚀变色。本研究主要采用石英晶体微天平(QCM)反应性监测技术,监测电沉积金属银石英晶振片在不同臭氧浓度、不同相对湿度中的质量变化,从而推测银在臭氧中的腐蚀机理。研究结果表明,臭氧浓度对银的腐蚀具有较大的影响。随着臭氧浓度的升高,银表面质量不断增大,腐蚀程度加剧。银对相对湿度具有较小的敏感性,在不同的相对湿度下,银表面质量变化相差不大。据此推断银在臭氧中的腐蚀首先表现为银与臭氧分解产生的原子氧反应生成氧化银(Ag2O),随着Ag2O膜的不断变厚,氧化膜顶层生成过氧化银(AgO),AgO是由Ag2O与原子氧反应生成。

Ozone has strong oxidation and corrosion effect on cultural relics,especially on silver relics,in the museum environment.In this study the quartz crystal microbalance(QCM) was used for investigation of mass change of silver-electrodeposited quartz crystals at different ozone concentrations and at different relative humidies.The mechanism of silver corrosion by ozone was also investigated.The results showed that the concentration of ozone has a great influence on silver corrosion.With an increase in ozone concentration,the mass of the silver surface gradually increased and the extent of corrosion became aggravated.Silver is less sensitive to relative humidity.At different relative humidities,the mass change of the silver surface was similar.When exposed to ozone,silver initially reacts with atomic oxygen formed from ozone decomposition to form silver oxide(Ag2O).As Ag2O film grows thicker,a layer of silver peroxide(AgO) forms on the top of the oxide film.AgO is formed by reaction between Ag2O and atomic oxygen.