磷酸与单宁酸复合缓蚀剂对出土铁质文物锈层化学转化研究

The Chemical Conversion Research of Corrosion Layer of Iron Relics Unearthed Based on Phosphoric and Tannic Acid Composite Inhibitor

摘要: 基于出土铁质文物材质状态，使用磷酸和单宁酸复配出一种复合缓蚀剂，可改善铁质文物锈层结构，提高文物锈层耐蚀性。出土铁质文物一般锈蚀严重，显微观察看见锈蚀产物具有明显的分层结构。结构复杂，包括α-FeOOH，γ-FeOOH，α-Fe₂O₃，γ-Fe₂O₃等。将磷酸和单宁酸按7:1的质量比复配成1%的水溶液，处理出土带锈铁质文物后，运用扫描电镜–能谱分析表明，该复合缓蚀剂可在铁质文物表面形成一层化学转化的缓蚀膜，缓蚀膜中C、P元素含量显著增高，为磷酸、单宁酸与铁锈形成的产物。磷酸除了富集在缓蚀膜中之外，磷酸还有向铁质文物内部扩散的趋势。磷酸、单宁酸复配型缓蚀剂存在使铁质文物表面不稳定的锈蚀转化为稳定锈蚀的趋势。从而提高铁质文物的耐蚀性能。同时该复合缓蚀剂处理的带锈铁质文物，锈层颜色可基本维持原貌，符合文物保护要求。

Abstract: According to the saved state of unearthed iron relics, phosphoric and tannic acid composite inhib-itor has been used to protect them. The results show that the composite inhibitor converts the structure of corrosion layer to more stable state. The corrosion layer is quite complex which is combined with high valence mixture of rust such as α-FeOOH, γ-FeOOH, α-Fe₂O₃, γ-Fe₂O₃ and so on. Confecting phosphoric and tannic acid composite inhibitor solution with mass ratio of 7:1 to protect iron relics unearthed, using scanning electron microscopy and energy dispersive spectrum observe iron relics, the results show that surface of iron relics can form a quite stable inhibitor film which is consisted of the product of phosphoric acid, tannic acid and iron corrosion. Phosphoric acid accumulates on inhibitor layer and trends to spread to inner iron relics. Phosphoric and tannic composite inhibitor can convert active rust to stable rust and improve the corrosion resistance of iron relics without color difference.