Improved ceramifiable properties of silicone resin coating by the combination of aluminum hydroxide and aluminum phosphate

Ceramifiable coatings, renowned for their exceptional resistance to high temperatures, oxidation, and corrosion, are widely used in fields such as power transmission and aerospace. In this study, a ceramifiable coating with a thickness of 0.3 mm was prepared via the scrape-coating method using silicone resin as the matrix and a 0.5 mm mica plate (MP) as the substrate, with aluminum hydroxide (ATH), aluminum phosphate (AP), mica powder, wollastonite, and glass powder as fillers. The synergistic effects of ATH and AP on the refractory properties and ceramization behavior of the coating were investigated. Results show that when the mass ratio of ATH to AP is 1:2, the coated mica plate exhibits a flexural strength of 36.9 MPa after 10 min of flame ablation (1,150–1,200 °C), significantly higher than that of an uncoated 0.8 mm mica plate (13.5 MPa). The crystalline phase composition and microstructure of the coating after flame ablation were characterized by XRD and SEM. Analysis indicates that ATH decomposes at high temperatures to form aluminum oxide, which acts as a ceramic filler participating in the formation of the ceramic framework. Meanwhile, aluminum phosphate enhances the bonding between ceramic fillers and promotes the ceramization reaction.