Preparation of Antireflective Silica Coating by the Sol-Gel Method for Heliothermic Power Plants

This work deals with the deposition of a thin layer of porous silica antireflective coating onto glass substrates. The films were deposited with different withdrawal speeds and heat-treated at 425°C for 30 minutes. The effects of heat treatment and film deposition rate on the films reflectance were evaluated. The diffuse reflectance was measured using ultraviolet-visible (UV-Vis) spectroscopy. Scanning electron microscopy (SEM) was used for microstructural evaluation of the films. The water contact angle upon the films surface was evaluated using a tensiometer and was based on the sessile drop technique. The mechanical characteristics of the films were evaluated by tape test and pencil hardness. The obtained sol-gel silica coatings were homogeneous and free of cracks. UV-Vis analysis of the glass substrate revealed a reflectance value of 3.86%, whereas the lowest reflectance value obtained for antireflective coatings was 2.72%. The contact angle measurement showed that, for all films, there was wetting of the film by water, characterizing them as hydrophilic. The adhesion of the films were 4B and the pencil hardness were 3H.

本研究围绕玻璃基底上多孔二氧化硅减反射薄膜的沉积工艺展开。实验采用不同提拉速率制备薄膜，并将其置于425℃环境中热处理30分钟。考察了热处理工艺与薄膜沉积速率对薄膜反射率的影响。采用紫外-可见（UV-Vis）光谱法测定薄膜的漫反射率；利用扫描电子显微镜（SEM）对薄膜的微观结构进行表征。通过表面张力仪结合静滴法测试薄膜表面的水接触角以评估其润湿性。采用胶带试验与铅笔硬度法表征薄膜的力学性能。所制备的溶胶-凝胶（sol-gel）二氧化硅涂层均匀无裂纹。对纯玻璃基底的紫外-可见光谱分析显示其反射率为3.86%，而所制备的减反射薄膜的最低反射率仅为2.72%。水接触角测试结果表明，所有薄膜表面均能被水润湿，表现为亲水性。薄膜的附着力等级为4B，铅笔硬度为3H。