The reduction in rheological parameters and dissolution rate of precursors in geopolymer coatings during early hydration significantly contributes to sagging. This study aims to improve the sag resistance of these coatings by incorporating diatomite filler. Rheological testing was conducted to assess the impact of diatomite and its concentration on yield stress, plastic viscosity, and thixotropy of the geopolymer coatings. The results indicated that diatomite's large specific surface area and high reactivity have a significant influence on the rheological parameters and early dissolution rate of precursors. With a diatomite concentration of 1.1%, the coating exhibited a yield stress of 2.749 Pa and a plastic viscosity of 0.921 Pa·s, maintaining stability, homogeneity, and no sagging at a thickness of 600 μm. Furthermore, the highly active SiO2 in diatomite participates in the secondary hydration reaction of the geopolymer materials, leading to the formation of substantial C-(A)-S-H gel. This gel enhances internal interconnectivity within the coating, thereby improving its rheological and mechanical properties.

Given of the outstanding versatile properties, the multilayered anti-corrosion coatings have drawn great interests in academic and engineering fields. However, the application of multilayered coatings is restricted by some limitations such as low interlayer compatibilities, harsh preparation process, etc. This work introduced a composite film fabricated on 2A12 aluminum alloy surface, including an anodic oxide film, a sol-gel film as well as a layer-by-layer (LBL) self-assembling film from bottom to top. The microstructure and elemental characterization indicated that the finish of the coating with the LBL film resulted in a closely connected multilayered coating with a smoother surface. The anticorrosion performance was systematically evaluated in the simulated corrosive medium and neutral salt-spray environment. The intergrated coating with the LBL film presented an excellent anticorrosion ability with the system impedance over 108 Ω•cm² and the self-corrosion current density two orders of magnitude lower than that of the other coatings. After the acceleration test in salt-spray environment, the multilayered coatings could still show a good protective performance with almost no cracks and no penetration of chloride ions. It is believed that the as-constructed multilayered coating with high corrosive properties and fine surface state will have promising applications in the field of anticorrosion engineering.