出土铁器文物的脱盐清洗研究

Study of desalting treatment of excavated iron antiquities

测试了铁在含不同浓度Cl-、SO42-水溶液中的腐蚀速度和电化学极化曲线。结果表明，在通空气的情况下，Cl-和SO42-浓度的增大能加速铁的腐蚀，而在密闭情况下就没有这种影响，说明铁器在地下不通空气的环境中相对较稳定。但出土铁器在大气环境中会受到Cl-和SO42-的加速腐蚀，只有及时地排除这些有害物质，才有可能减缓铁器在大气环境中的腐蚀。根据铁在水溶液中腐蚀行为的电位-pH图判断，在pH=9－13的碱性水溶液中铁的腐蚀较小，因而可用添加有缓蚀剂、表面活性剂和多种助洗剂成分的复配碱性脱盐清洗液来处理出土铁器。它比铁在蒸馏水中的腐蚀速度小四十多倍，且去污和脱盐效率高。这对恢复出土铁器的面貌及进一步化学稳定转化铁器表面的锈层都具有重要的作用。

By determining the corrosion rate and electrochemical polarization curve of iron in NaCl and Na2SO4 solutions of different concentration, it is proved that the corrosion rate of iron samples are accelerated in aerated solution but not influence in hermetic solution. So the iron antiquities is stable during burials, but it is not stable in atmospheric enviroments and the corrosion will be accelerated. It is onlythe removement of these impourity (Cl-, SO42- etc.) in time that corrosion rate of iron antiquities can be slowed down in atmosphere. According to the potential and pH pourbaix diagram, the corrosive behavior of iron is less at pH of 9-13 in alkaline solutions. For this reason the treatment of iron antiquities in solutions containing corrosion inhibitors, surface active agents and auxiliaries etc, The corrosion rate of iron antiquities in the solution is forty. fold less than in distilled water, the efficiencies of rust removing, desalting and washing are also better. So it is important to discover the original shape of excavated iron antiquities and stabilize the rust of iron surface.