Ding Rao, Li Weidong, Yang Zelin, Xu Changsong, Lu Xiaoke
Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201899, China.
Key Scientific Research Base of Ancient Ceramics, State Administration for Cultural Heritage, Shanghai 201899, China.
Materials (Basel). 2023 Jan 30;16(3):1176. doi: 10.3390/ma16031176.
Dalian Island is located in the sea area near Pingtan County, Fujian, Southeast China. The sea area used to be the junction of the eastern and western ship routes on the Maritime Silk Road, and is also an important region for underwater archaeology in China. This study focused on a sauce-glazed ware of the Song Dynasty, with serious degradation, which was salvaged out of the water at the Dalian Island Wharf. Optical microscopy, scanning electron microscopy, X-ray diffraction analysis, and micro-Raman spectroscopy were used to comprehensively analyze the composition, phase attributes and microstructure of the ware and the surface-attached coagula. The findings revealed that the sea wave-borne debris scoured the surface of the ware, causing mechanical damage to varying degrees and a significant decrease in its degradation resistance. This was the primary factor accounting for the poor preservation state of the salvaged ceramic ware, and the precondition for the subsequent attachment of marine organisms and the deposition of inorganic pollutants. The calcareous skeletons formed on the surface induced by the bio-mineralization of coralline algae (a type of marine plant) could resist the mechanical action caused by the motion of sea waves, thereby slowing down the ware's degradation process. In other words, the calcareous skeletons played a 'bio-protective' role to a certain degree. In addition, inorganic pollutants represented by iron rusts also participated in the corrosion of the glaze. Some pollutants were directly deposited on the pits and cracks on the surface of the ware, which brought stress to the glaze and glaze/body interface, causing the glaze to further crack and spall. Moreover, iron rusts reacted with the glaze, leading to chemical alteration, accompanied by the formation of iron silicate as the alteration product. Anorthite crystals in the interlayer did not participate in the reaction but remained at the original position. The alteration product gradually replaced the original glass phase of the glaze and entered into the body via pores and cracks. In conclusion, the complex degradation morphology of the salvaged sauce-glazed ware could be attributed to the combined action of mechanical damage, marine bio-fouling, and chemical alteration.
大练岛位于中国东南部福建省平潭县附近海域。该海域曾是海上丝绸之路东西方航线的交汇处，也是中国水下考古的重要区域。本研究聚焦于一件宋代酱釉瓷器，其腐蚀严重，是从大练岛码头出水打捞的。利用光学显微镜、扫描电子显微镜、X射线衍射分析和显微拉曼光谱对该器物及其表面附着的凝结物的组成、相属性和微观结构进行了综合分析。研究结果表明，海浪携带的碎屑冲刷器物表面，造成不同程度的机械损伤，使其抗腐蚀能力显著下降。这是打捞出水的陶瓷器保存状态不佳的主要因素，也是随后海洋生物附着和无机污染物沉积之前提条件。由珊瑚藻（一种海洋植物）生物矿化作用在表面形成的钙质骨架能够抵御海浪运动引起的机械作用，从而减缓器物的腐蚀过程。也就是说，钙质骨架在一定程度上起到了“生物保护”作用。此外，以铁锈为代表的无机污染物也参与了釉层的腐蚀。一些污染物直接沉积在器物表面的凹坑和裂纹上，给釉层和釉/胎界面带来应力，导致釉层进一步开裂和剥落。而且，铁锈与釉层发生反应，导致化学蚀变，伴随有硅酸铁作为蚀变产物的形成。层间的钙长石晶体未参与反应，而是留在原位。蚀变产物逐渐取代釉层原来的玻璃相，并通过孔隙和裂纹进入胎体。综上所述，打捞出水的酱釉瓷器复杂的腐蚀形态可归因于机械损伤、海洋生物污损和化学蚀变的共同作用。
