故宫古建筑用铁钉基体、铁锈剖析及缓蚀保护

Rust Analysis and Corrosion Protection of Iron Nail in the Palace Museum Buildings

目的对故宫古建筑用铁钉进行检测并保护。方法利用金相显微镜对铁钉基体进行金相组织分析,采用体视显微镜对锈层表面进行观测,借助扫描电镜、X-射线能谱仪(SEM-EDX)及X射线衍射仪(XRD),对锈蚀产物化学组成进行了成分测试。测定动电位极化曲线以研究硅酸盐复配缓蚀剂对铸铁电极预膜缓蚀后的电化学行为,通过加入聚乙二醇(PEG)的方法对硅酸盐复配缓蚀剂进行改性。结果故宫古建筑用铁钉基体组织为球墨铸铁,表面锈蚀产物主要呈现红褐色及黑褐色,经分析主要由Fe2O3、Fe3O4和α-FeOOH组成,铁钉表面白色物的主要成分为CaCO3。极化曲线法测得硅酸盐复配缓蚀剂预膜后的缓蚀效率为20.53%,改性后的缓蚀效率达到81.20%。交流阻抗测试、耐盐雾测试及室外暴露测试都表明,改性后缓蚀剂具有一定的缓蚀性能。结论故宫古建筑用铁钉表面锈蚀严重,需要通过系列保护手段减缓腐蚀速率。硅酸盐复配缓蚀剂预膜使用效果不佳,改性后的缓蚀剂对模拟铁钉的铸铁试样起到一定的缓蚀效果,且表面颜色变化小,满足铁质文物保护需求。

The work aim to detect and protect the iron nails used in the Palace Museum buildings.Metallographic analysis of the iron nail matrix was performed with a metallographic microscope,and the surface of the rust layer was observed by a stereomicroscope.Scanning electron microscopy,X-ray spectroscopy(SEM-EDX),and X-ray diffraction(XRD)were used to test the chemical composition of the corrosion products.The kinetic potential polarization curve was measured to study the electrochemical behavior of silicate compound corrosion inhibitors on the pre-film corrosion inhibition of cast iron electrodes.Polyethylene glycol(PEG)was added to modify the silicate compound corrosion inhibitors.The structure of the iron nails matrix used for the Palace Museum buildings was nodular cast iron.The surface corrosion products were mainly reddish brown and dark brown.After analysis,the corrosion products were mainly composed of Fe2O3,Fe3O4 andα-Fe OOH.The main component of the white substance on the surface of the nails was CaCO3.The corrosion inhibition efficiency measured by the polarization curve method was 20.53%after pre-filming with silicate compounded inhibitor,and the corrosion inhibition efficiency reached 81.20%after modification.AC impedance test,salt spray resistance test and outdoor exposure test all showed that the modified corrosion inhibitor had certain corrosion inhibition performance.The surface of the iron nails used in the Palace Museum buildings was heavily rusted,and a series of protection measures are needed to slow the corrosion rate.The effect of silicate compound inhibitor after pre-filming is not good.The modified inhibitor has certain corrosion inhibition effect on the cast iron sample simulating iron nails,and the surface color changes slightly,which meets the protection requirements of iron cultural relics.