Novel formulated alumina-silica hybrid sol for the entire consolidation of waterlogged decayed ivory from Sanxingdui ruin site

Large amount of ivory was excavated from Sanxingdui site which was waterlogged, severely degraded and in urgent need for conservation. There has been much effort for the conservation of waterlogged ivory by scientists. However, due to a lack of appropriate conservation material and the need to use non-destructive methods, no satisfactory results have been achieved previously. In this work, a novel formulated water-based Al–Si hybrid sol of size about 20 nm was prepared and introduced through a quasi-dynamic equilibrium method to waterlogged ivory tusk for the purpose of conservation. Good conservation performance could be achieved, since Al–Si sol gradually permeates into the interior of the ivory, distributes homogeneously and connects the loose components of ivory. Samples treated with appropriate amount of Al–Si sol displayed satisfactory compressive strength and porous intact structure. It was found that the fluidity of Al–Si sol had a significant influence on the conservation effect. Moreover, Al–Si sol not only consolidated HAP but also worked well on the soil embedded in unearthed ivory, which was beneficial to conserve ivory intactly. Slightly negatively charged Al–Si hybrid gel could interact with ivory matrix through multiple interactions including van der Waals force, electrostatic interaction, chemical and hydrogen bonding.