In Situ Reinforcement of Polysilazane in the Preservation of Excavated Water-Bearing Decayed Ivory Based on Biointerface Water-Triggered Reactions

The excavated ivory from the Sanxingdui archeological site is typically found in a water-bearing and extremely fragile state due to prolonged exposure to complex burial conditions, posing significant challenges for conservation efforts. Particularly concerning are severely decayed and water-bearing ivory specimens, whose crumbly texture places them on the brink of structural collapse. As a typical biogenic porous material, excavated ivory dentin contains a complex pore–crack network and pore–water biointerfaces. Under such conditions, the conventional strategy of “dehydration followed by reinforcement” often leads to structural collapse and irreversible damage. In this study, a biointerface water-triggered polysilazane consolidation method was proposed for severely decayed, water-bearing ivory dentin, enabling long-term and effective in situ reinforcement without dehydration pretreatment. Research indicates that both polysilazanes can penetrate into the interior of excavated ivory and undergo hydrolysis–condensation reactions with internal water to form a three-dimensional Si–O–Si network, thereby reconstructing the fragile pore–crack system. In parallel, a thin transparent siloxane layer is formed on the ivory surface, enabling simultaneous reinforcement and protection while maintaining the original appearance. Compared to unreinforced excavated ivory, polysilazane-reinforced specimens exhibited a hydrophobic transformation with static water contact angles reaching 125–129°. Concurrently, the hardness and compressive strength of the reinforced excavated ivory increased by approximately 26.15–50.94 and 24.25–112.97%, respectively. The color difference Δ E between the pre- and postreinforcement dentin remained below 1, adhering to the principle of “minimal intervention.” This study provides an efficient and safe in situ consolidation strategy for severely decayed water-bearing ivory and offers a unique perspective on the stabilization mechanism of biogenic porous materials involving interfacial water reactions, with significant application value in cultural heritage conservation.