铁质文物常用除锈试剂的除锈效率及其腐蚀性的比较研究

Comparative study of rust removal efficiency and corrosiveness of commonly-used reagents for iron artifacts

为比较铁质文物常用除锈试剂的除锈效果,为铁质文物保护中除锈试剂的选择提供建议,对磷酸、柠檬酸、酒石酸、Na2EDTA等多种试剂进行了实验研究。使用铁锈粉末、铁锈块、铸铁片、带锈铸铁片等多种样品进行了实验,以定量研究试剂的除锈效率以及对铁基体的腐蚀性。结果表明:几种试剂对铁基体的腐蚀都很强烈,且腐蚀铁基体的速率远高于溶解铁锈的速率,加入缓蚀剂可以显著降低铁基体的腐蚀;磷酸在几种试剂中除锈能力最强,对粉末样品和锈块样品都具有较好的除锈效果,但需要过量才能保证除锈作用持续,而少量磷酸则对铁器有钝化保护的作用;柠檬酸、酒石酸、Na2EDTA对铁锈粉末有一定的溶解作用,但对锈块的除锈效率很低。因此,在铁质文物保护中,添加缓蚀剂的磷酸是比较合适的除锈试剂。

In order to compare the rust removal effects of commonly-used reagents for iron artifacts and to provide suggestions for the selection of reagents during iron artifact conservation,we carried out experimental studies using phosphoric acid,citric acid,tartaric acid and Na2EDTA.Various kinds of samples such as rust powder,rust fragments,cast iron sheets and rusted cast iron sheets were used to quantitatively study the rust removal efficiency of the reagents and their corrosiveness to the iron substrate.The results show that 1)each of the reagents causes strong corrosion on the iron substrate,and that the corrosion rate is much higher than the rust removal rate but can be reduced by the addition of inhibitors;2)among these reagents,phosphoric acid has the strongest ability to remove rust and it works well on both powder and fragment samples,but excessive amounts of phosphoric acid are needed to ensure the continuous rust removal,since a small amount of phosphoric acid has a passivation effect;3)citric acid,tartaric acid and Na2EDTA can dissolve the rust powder to some extent,but their efficiencies for rust removal from rusted fragments are very low.Consequently,phosphoric acid with a corrosion inhibitor is a suitable rust removal reagent in the conservation of iron artifacts.