硅基气凝胶是一种新型低导热率保温材料,其在寒冷地区建筑应用中的耐久性取决于冻融环境下的性能稳定性。为研究冻融环境对硅基气凝胶物理力学性能的影响,开展了0次(对照组)、100次、200次和300次冻融循环试验,系统分析了硅基气凝胶板含水率、微观结构、弯曲性能、压缩性能及振动质量损失的演变规律。结果表明:冻融作用导致气凝胶含水率显著增加,水分冻胀效应破坏其纳米多孔结构,进而引起材料性能的不可逆衰减。随着冻融次数增加,材料性能呈现阶段性退化特征:与初始阶段相比,经100次、200次和300次循环后,抗弯承载力分别下降17%、26%、40%,压缩强度分别衰减6%、12%、17%,压缩弹性模量分别降低4%、6%、10%。质量损失率由初始状态的0.98%持续上升至300次循环时的3.23%。基于试验数据,建立了冻融循环次数与性能保留率之间的定量关系模型,并提出通过表面疏水改性和纤维增强提升材料抗冻融性能的技术途径。研究成果为硅基气凝胶在寒区建筑中的耐久性设计与应用提供了依据。

Silicon-based aerogel is a new type of thermal insulation material with low thermal conductivity,and its durability in building applications in cold regions depends on the performance stability under freezing-thaw conditions.In order to study the influence of freezing-thaw environments on the physical and mechanical properties of silicon-based aerogels,0 (control group),100,200 and 300 freeze-thaw cycle tests were carried out,and the evolution laws of moisture content,microstructure,bending performance,compression performance and vibration mass loss of silicon-based aerogel plates were systematically analyzed.The results showed that the freezing-thaw effect led to a significant increase in the moisture content of aerogels,and the moisture frost heave effect destroyed their nano-porous structure,which in turn caused irreversible attenuation of material properties.As the number of freeze-thaw cycles increased,the material properties exhibited stage degradation characteristics.Compared with the initial stage,after 100,200 and 300 cycles,the flexural bearing capacity decreased by 17%,26%,40%,the compressive strength decreased by 6%,12%,17%,and the compressive elastic modulus decreased by 4%,6%,and 10%,respectively.The mass loss rate continued to increase from 0.98% in the initial state to 3.23% after 300 cycles.Based on the experimental data,a quantitative relationship model between the number of freeze-thaw cycles and the performance retention rate was established,and a technical approach to improve the frost-thaw resistance of materials through surface hydrophobic modification and fiber reinforcement was proposed.The research results provide a basis for the durability design and application of silicon-based aerogels in buildings in cold regions.