出土铁质文物锈蚀形态的原位分析及其机理

In-Situ Analysis of the Rust Morphology of Unearthed Iron Relics and Its Mechanism

利用超景深显微镜、金相显微镜、扫描电子显微镜、能谱仪、显微拉曼光谱仪等,对六件湖北地区出土铁质文物的锈蚀状况进行了原位分析,以深入研究铁质文物不同锈蚀形态。结果表明,铁质文物的锈蚀形态可分两类:(1)一般铸铁器物的原始形态清晰可辨,其锈层有组织“痕像”残存,其锈蚀产物为铁的氧化物和C;(2)一般熟铁器物的原始形态被锈层破坏,其锈层中无组织“痕像”,其锈蚀产物通常包括α-FeOOH、Fe_(3)O_(4)、α-Fe_(2)O_(3)、β-FeOOH等。铸铁中大量渗碳体和石墨的存在是锈层中残存“痕像”组织,并保持器物原始形态的重要原因。Ⅰ型锈一般保留器物原始形态特征,若为无害锈则予以保留;Ⅱ型锈往往破坏了器物原始表面,导致纹饰器型难辩,即使为无害锈也需适当去除。

In situ analysis was conducted on the corrosion status of six iron cultural relics unearthed in Hubei Province using a super depth microscopy,metallographic microscopy,scanning electron microscopy energy spectrometer,and micro Raman spectrometer,in order to further study the different corrosion forms of iron cultural relics.The results show that the corrosion forms of iron artifacts could be divided into two categories.(1)The original form of general cast iron objects was clear and distinguishable,and the rust layer had organized"scar like"remnants,and the corrosion products were iron oxides and C.(2)The original form of general wrought iron was destroyed by the rust layer,and there were no organized“traces”in the rust layer.The rust products includedα-FeOOH,Fe_(3)O_(4),α-Fe_(2)O_(3),β-FeOOH,etc.The presence of a large amount of carbides and graphite in cast iron was an important reason for the residual“trace like”structure in the rust layer and the preservation of the original shape of the object.Type I rust generally retains the original morphological characteristics of the object,and if it is harmless rust,it is preserved.Type II rust often damages the original surface of the object,making it difficult to distinguish the decorative pattern,harmless rust also should be removed appropriately.