金属锌与PTFE改性建筑陶瓷表面的润湿性能研究

Surface Wettability of Building Ceramics Modified by Zinc Metal and PTFE

目的结合金属锌和聚四氟乙烯(PTFE)改性技术,制备具有微纳复合结构表面的超疏水、防污染、自清洁建筑陶瓷。方法基于现有工业陶瓷生产方法,在陶瓷釉料中掺入质量分数为60%的金属锌粉,通过高温烧结在陶瓷表面构建微纳复合结构,随后在其表面喷涂PTFE涂料进行低表面能处理,从而制得超疏水性建筑陶瓷。利用扫描电镜和光学轮廓仪,观察陶瓷表面微纳形貌。通过X射线能谱仪,对陶瓷表面的化学元素组成进行分析。使用光学测量系统,测量水滴在陶瓷表面的静态接触角和滚动角。根据测试结果分析5种烧结温度对陶瓷表面微纳结构和润湿性能的影响。结果随着烧结温度的升高,陶瓷表面的均方根粗糙度(Sq)先增大后减小,对应的疏水性能先增强后减弱。在1000℃(保温10 min)烧结温度下,Sq达到最大值,为(17.52±2.54)μm,表现出最优的超疏水性能,其静态接触角和滚动角分别为165.6°和8.2°,并且该表面展示出良好的防污能力和耐磨性。结论液滴与陶瓷表面接触时,由金属锌粉烧结形成的微纳复合结构和低表面能的PTFE起耦合协同作用,陶瓷表面与液滴形成固-液-气三相复合接触的Cassie-Baxter状态,即阻隔的空气垫阻碍液体浸入微纳复合结构之中。随着陶瓷表面粗糙度的增加,气-液接触面积增加,从而使得疏水性能得到提升。

The pollution of building ceramics has grown to be a significant issue in people’s lives.Interestingly,superhydrophobic surfaces offer new possibilities for anti-fouling strategies.This work aims to construct micro-nano composite microstructured surfaces through metal zinc and polytetrafluoroethylene(PTFE)modification technology for building ceramics to achieve superhydrophobic,anti-fouling,and self-cleaning performance.Based on the production method of industrial ceramics,the ceramic glaze was mixed with metal zinc with a mass ratio of 60%,and the micro-nano composite structure was constructed on the ceramic surface by high-temperature sintering.Then,the surface was sprayed with PTFE coating for a low surface energy treatment,so as to obtain superhydrophobic building ceramics.A scanning electron microscope and optical profiler were used to observe the micro-nano morphology of the ceramic surface,X-ray energy dispersive spectrometer(EDS)was employed to analyze the chemical element composition of the surface,and an optical measurement system was utilized to measure the static contact angle and rolling angle of water droplets(6μL in volume)on the ceramic surface.According to the experimental results,the effects of five sintering temperatures(i.e.,925℃,950℃,1000℃,1025℃,and 1050℃)on the micro-nano structures and wettability of the ceramic surface were analyzed.Results show that during the sintering process,a small part of the potassium feldspar,calcite,kaolin,and other components in the glaze composition formed a molten state,while most of them remained in the original state.The granular metal zinc powder was partially oxidized and then deposited on the surface of other unreacted glaze components under the action of gravity.At the same time,the ceramic body is exhausted a lot during the sintering process,so a large number of cracks and hole structures are formed on the surface of the glaze layer.Besides,the EDS analysis indicates that the ceramic surface is mainly composed of elements Zn and O,where the atomic percentage of Zn and O were 68.55%and 15.50%,respectively,and there was a small amount of F element.In addition,as the sintering temperature increased,the root-mean-square roughness(Sq)of the ceramic surface first increased and then decreased,and the hydrophobic properties of the surface showed the same trend.At the sintering temperature of 1000℃(holding for 10 min),Sqreaches the maximum value of(17.52±2.54)μm,showing the excellent superhydrophobic property,where the static contact angle and rolling angle were 165.6°and 8.2°,respectively.Moreover,the as-prepared ceramic surface exhibits good anti-fouling properties to stain liquids and outstanding abrasion resistance through multiple abrasion test cycles.The related mechanisms have been demonstrated that when the droplet is in contact with the ceramic surface,the micro-nano composite structure formed by sintering metal zinc powder and PTFE with low surface energy play a coupling and synergist effect,resulting in a Cassie-Baxter state of solid-liquid-gas composite between the ceramic surface and the water droplet,that is,the blocking air cushion hinders the liquid immersion into the micro-nano composite structures.As the surface roughness of the ceramic surfaces,the gas-liquid contact area increases,thereby improving the hydrophobicity.This study will raise promising prospects for anti-fouling applications in the building ceramic industry.