Influence mechanism of added low-melting glass powder on the properties of high-temperature organic composite coatings.

Two formulations of high-temperature organic composite coatings containing Al flakes, nano-TiO 2 were designed and low-melting glass (LMG) powder was added to the second for comparison. The properties of two coatings before and after the heat exposure tests were investigated. At room temperature, the large particles of LMG powder shortened the diffusion path of corrosive medium and had low interface binding strength with Al flakes, which has a negative effect on the barrier properties and strength of the as-prepared coating. After exposed to 600 °C for 300 h, the binder—silicone-modified acrylic resin—decomposed into silica, releasing gaseous products and generating a large amount of cavities inside the coating. Barrier properties and strength of the coating without added LMG powder severely deteriorated. At high temperatures, LMG in the viscous flow state infiltrated into the surrounding cavities by capillary action, forming a glass network and leaving in-situ holes. These holes deteriorated the barrier properties of the coating. The glass network filled in the cavities increased the coating strength and had a barrier effect on the diffusion of corrosive medium. [ABSTRACT FROM AUTHOR]