Application of polysilazane in coatings

Organosilicon compounds possess many unique and excellent physical and chemical properties, which have long attracted widespread attention. Research on polysilazanes, which have Si-N bonds, has also made significant progress in recent decades. While research on polysilazanes has primarily focused on ceramic synthesis, high-temperature-resistant silicone rubber, and composite materials, their potential applications in coatings are also gaining traction. Polysilazanes contain silicon-nitrogen bonds and nitrogen-hydrogen chains, which impart numerous unique properties. While their mechanisms of action are still unclear, these properties are crucial for coatings.
 

Polysilazanes are widely used in coating and varnish formulations, demonstrating their excellent weather resistance, UV resistance, corrosion resistance, stain resistance, graffiti resistance, scratch resistance, and heat resistance. Polysilazane clearcoats typically have a dry film thickness ranging from 10 nm to 2 μm. Compared to amino alkyd clearcoats and two-component polyurethane clearcoats, polysilazane clearcoats offer superior gloss retention and weathering resistance. Compared to silicone-modified polyester clearcoats, polysilazane clearcoats offer superior heat resistance. Polysilazane-coated aluminum exhibited no corrosion after 2.400 hours of salt spray resistance testing (ISO 7253-2001), and steel exhibited no corrosion after 2.400 hours of condensation water testing (ISO 6270.2-2005). Polysilazane coatings maintain a water contact angle of approximately 95° over time, and with the use of appropriate additives, this water contact angle can be increased to over 120°. These coatings are low-viscosity, solvent-free, and fluorine-free, and exhibit excellent adhesion to most substrates and exceptional hardness (9H+).
 

When polysilazane is heated to a minimum of 450°C, the polymer is ultimately converted into an inorganic ceramic (SiOx), which exhibits extremely high hardness (9H) and ultra-high heat resistance (up to 1.800°C). Furthermore, polysilazane can be cold-blended with most non-reactive resins, such as thermoplastic acrylics, silicones, and hybrids of organic polysilazane and inorganic polysilazane.