Abstract: Ceramics exposed to underwater environments for prolonged periods are vulnerable to physical, chemical, and biological corrosion. X-ray fuorescence（XRF）spectroscopy, scanning electron microscope-energy dispersive X-ray (SEM-EDX) spectrometry, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and steady-state fluorescence photoluminescence (PL) spectroscopy were used to analyze the microstructure and structural composition of the two green-glazed ceramic samples salvaged from the Yangtze Estuary II shipwreck. The results revealed that fabrication of the green-glazed ceramic samples involved applying a low-temperature green lead glaze on the surface of a combined white matrix and transparent ceramic layer mainly composed of quartz and mullite, which were ¯red at high temperatures. On the green-glazed ceramic samples recovered from sediments in the Yangtze Estuary, corrosive pits, crack extensions, and corrosive products were observed mainly comprising Pb(OH)Cl caused by microbial and chemical changes on the surface of the green-glazed layer. The corrosive substances were assumed to have contributed to the continuous expansion of cracks in the green-glazed layer, which had penetrated the interface between the green-glazed layer and the connecting transparent ceramic layer. Moreover, the cracked region of the green-glazed layer and the interface between the transparent ceramic layer and the green-glazed layer contained highly hygroscopic salts, including NaCl, CaCl2, Na2SO4 and CaSO4. The osmotic pressure of these salts and the swelling effect attributable to the absorption of water had accelerated the detachment of the green-glazed layer. These finndings will make a considerable contribution to furthering the understanding of the corrosion and glaze detachment of salvaged ceramics and provide scientific evidence for the protection of salvaged ceramics.

Key words: salvaged ceramics, microbial corrosion, glazed layer detachment, high hygroscopic salt, osmotic pressure effect