粉煤灰基地聚合物无机涂料的制备与性能

以低钙型粉煤灰为主要原料,硅酸钠和氢氧化钠为复合碱激发剂,硅烷偶联剂(KH550)为增强材料,硅丙乳液为辅助成膜物质制备地聚合物无机涂料。研究了硅烷偶联剂掺量、反应温度以及水固比对地聚合物无机涂料的成膜性、耐水性和耐洗刷性等性能的影响,并通过XRD、FTIR、SEM、TG-DSC分析了无机涂料的微观结构及其耐高温性能。结果表明,当制备温度为60 ℃、水固比为0.31(质量比)、硅烷偶联剂掺量为3.6%(质量分数)时,地聚合物无机涂料在室温下的成膜性良好,无开裂现象,涂料24 h内质量吸水率为1.84%,耐洗刷性可达12 000次,7 d时硬度为154 s。地聚合物无机涂层内部主要是无定形的硅铝酸盐凝胶,硅烷偶联剂经水解、键合生成簇状产物填充在涂层的孔隙之间,增加了涂层的密实性,抑制了裂纹的产生。涂层在25~800 ℃的失重率为12.0%~13.0%,未发现明显的地聚合物热分解现象,说明涂层耐高温性能良好。

Preparation and Properties of Fly Ash-Based Geopolymer Inorganic Coatings

The fly ash-based geopolymer inorganic coatings were prepared with low-calcium fly ash as the main raw material, sodium silicate and sodium hydroxide as the composite alkaline activator, silane coupling agent (KH550) as the reinforcing material, and silicone acrylic emulsion as the auxiliary film-forming material. The effects of silane coupling agent content, reaction temperature and water-solid ratio on the film-forming property, water resistance and scrub resistance of geopolymer inorganic coatings were studied, and the microstructure and high temperature resistance of inorganic coatings were characterized by XRD, FTIR, SEM, TG-DSC. The results show that, when the preparation temperature, the water-solid ratio and the content of silane coupling agent are 60 ℃, 0.31 (mass ratio) and 3.6% (mass fraction), respectively. The obtained geopolymer inorganic coating has good film-forming performance at room temperature without cracking, the mass water absorption rate of the coating is 1.84% in 24 h, the scrub resistance reaches 12 000 times, and the hardness of 7 d is 154 s. The geopolymer inorganic coating is mainly composed of amorphous aluminosilicate gel. The cluster featured products formed by hydrolysis and bonding of silane coupling agent fill the pores of geopolymer coating, which increase the compactness of the coating and inhibit the generation of cracks. The mass loss rate of the coating is 12.0% to 13.0% when TG-DSC is measured between 25 ℃ and 800 ℃, and no obvious thermal decomposition is found, which indicates that the coating has good high temperature resistance.