石质文物保护用有机硅材料的防开裂问题研究进展

Progress in Research of Crack-Free Organosilane Consolidants for Stone Conservation

由于石质文物具有特殊的结构,所以易遭受来自环境的侵蚀。有机硅是常用的石质文物保护材料,它作用于基体孔隙,凝胶化,增强矿物粒子间作用力,可提高石质基体耐候性能,起到一定的加固作用。然而,有机硅材料作用在基体上后,在干燥收缩过程中常常发生开裂,这样反而加速石质基体受到的水盐破坏,严重时甚至造成基体的崩解。对有机硅进行化学改性可以在一定程度上抑制这种开裂,如添加弹性链段,添加纳米粒子,通过增大保护材料弹性模量或降低有机硅收缩过程中的毛细应力,可以起到一定的防开裂效果。简要回顾了有机硅运用于石质文物保护的历史,阐述了凝胶化干燥过程中的开裂机理,对近些年来防开裂的探索进行了分析。同时展望了不开裂的复合保护材料的应用前景,为今后的石质文物保护材料研究提供了思路。

Stone relics tend to be corroded by environment, due to their special porous structures. Organosilane consoli- dants are frequently used in protecting stone relics. The gels formed in stone porous by organosilanes can enhance strength of stone and improve its resistance to weathering. However, it is known that the resulting silica gel tends to develop cracks inside the stone as the gel shrinks during aging and drying, which may accelerate the erosion from environment and lead to serious problems. Modifying of organosilanes may control the issue to certain extent, by adding flexible segments or nanop- articles for instance. In this report, we first give a brief review on the h/story of development and use of organosilanes as consolidants and then demonstrate the possible mechanisms of gel cracking during drying and aging, and further discuss ootential wavs of obtainin~ crack-fr^e silical~ cnnscdid^nt~.