Enhanced heat and corrosion resistance of organic silicone coatings by dual shielding effects of Zn powder

Organic silicone coatings added with varying Zn content were developed to enhance heat and corrosion resistance in different corrosive environments. Zn was revealed to affect the adhesion strength between the coating and the substrate, and the 40% Zn-added coating demonstrated the best heat and corrosion resistance. In high-temperature environments, the volume expansion and melting deformation of Zn filled the defects of the coating and enhanced the physical shielding effect of the coating. In ambient-temperature environments, Zn provided the chemical shielding effect to the steel substrate by acting as an anode and providing cathodic protection. In high temperature-salt spray cyclic environments, the ambient-temperature corrosion products of Zn also filled the defects of the coating and enhanced the heat resistance in the high-temperature stage. ZnO generated at high temperatures preferentially adsorbed corrosive mediums in the ambient-temperature stage, hindering their diffusion to the substrate, thereby simultaneously enhancing the heat and corrosion resistance of the coating.