Research on the degradation of ancient Longquan celadons in the Dalian Island shipwreck

Eleven celadons with different degrees of degradation excavated from the Dalian Island shipwreck of the Yuan Dynasty (1271-1368 AD) were selected, and the degradation mechanism of the ancient porcelain at marine environment was investigated. The chemical composition, microstructure, and corrosion morphology of the samples were characterized. The results showed that these celadons can be divided into two types: transparent glazes and matt-opaque glazes. The glazes are subject to the combined effects of physical damage and chemical corrosion. The glaze surface became rougher through physical impact, and the increased surface area may also promote chemical corrosion. The mutual promotion of the two effects usually leads to more serious degradation. There are two possible corrosion mechanisms, depending on the glaze microstructure. Transparent glazes may experience the process of dissolution and reprecipitation. The crystallization-phase-separation structure in the matte glaze has lower chemical stability, which can contribute to more extensive corrosion.