Here are some methods to improve the bonding strength between polysilazane coatings and substrate materials:
Base pretreatment
Cleaning treatment:
Remove pollutants such as oil stains, dust, and impurities from the surface of the substrate. For example, for metal substrates, organic solvents (such as acetone, ethanol, etc.) can be used for wiping and cleaning, followed by rinsing with deionized water and drying to ensure surface cleanliness, allowing the polysilazane coating to better contact and adhere to the substrate.
For substrates such as ceramics and glass, ultrasonic cleaning can be used to remove small particles that are difficult to remove from the surface through ultrasonic cavitation, creating favorable conditions for subsequent coating.
Surface roughening:
By mechanical polishing, such as using sandpaper to polish metal, plastic and other substrates, the surface roughness is increased, and the contact area between the coating and the substrate is increased. After polishing, the metal surface will form a microscopic concave convex structure, and the polysilazane coating can be embedded in it, thereby improving the bonding force.
The method of chemical etching is also commonly used, for example, for some metal substrates, specific acid solutions can be used for etching to form micro pores or textures on their surfaces, improving the adhesion effect of coatings. Aluminum alloy substrates can be treated with an acidic etching solution containing fluoride, and then coated with a polysilazane coating, which significantly enhances the bonding strength.
By using sandblasting treatment, small pits and other rough structures are created on the surface of the substrate by high-speed spraying of sand particles, which is suitable for various material substrates, especially for some metal substrates with high hardness, and can effectively improve the bonding between the coating and the substrate.
Surface activation:
For plastic substrates, plasma treatment can be used to bombard the surface of the substrate with active particles in the plasma, causing the molecular chains on the surface to break and generate active groups such as free radicals, increasing surface energy, enhancing affinity with the polysilazane coating, and promoting better bonding of the coating. For example, after plasma treatment, polycarbonate plastic substrates can be coated with a polysilazane coating, which can significantly improve the bonding strength.
Metal substrates can undergo chemical activation treatment, such as using silane coupling agents to treat their surfaces. One end of the silane coupling agent can react with active groups such as hydroxyl groups on the metal surface, while the other end can react chemically with silicon related groups in the polysilazane coating, playing a "bridge" connecting role and strengthening the bond between the two.
Optimization of coating formula
Add adhesion promoter: Add suitable adhesion promoter to the polysilazane coating system, such as some organic compounds containing active functional groups such as carboxyl and amino groups. They can undergo chemical reactions or physical adsorption with the substrate surface and the polysilazane itself, improving the interface bonding between the coating and the substrate and enhancing the bonding strength.
Adjusting the solvent system: Select the appropriate solvent to prepare the polysilazane coating, ensuring good wetting and flowability of the coating, so that it can better spread on the substrate surface, fill the micro pores and other structures on the substrate surface, and thus closely adhere to the substrate. For example, some polysilazanes have better coating performance and substrate wettability in ketone solvents, and the use of such solvents can improve the bonding strength to a certain extent.
Optimization of coating process
Control coating thickness: Avoid coating too thick, as thick coatings can easily cause internal stress concentration, leading to coating peeling off from the substrate. Reasonably controlling the thickness of each coating can achieve the desired total coating thickness through multiple thin coatings, which can make the coating bond with the substrate more uniform and firm.
Coating method selection: Different coating methods have an impact on the bonding strength. For example, when spraying, it is necessary to control the pressure, distance, angle, and other parameters of the spray gun to ensure that the coating is evenly atomized and adheres to the substrate in an appropriate state; When dipping, attention should be paid to the dipping speed and pulling speed to ensure that the coating is uniform and can bond well with the substrate. For substrates with complex shapes, a composite coating method combining spray coating and dip coating may achieve better bonding effects.
Optimization of curing process: Strictly follow the curing requirements of the polysilazane coating, and control the curing temperature, time, atmosphere, and other conditions. Appropriate curing conditions can enable the coating to fully crosslink and solidify, forming a stable structure while better bonding with the substrate. For example, some polysilazane coatings require thermal curing under a specific heating curve. Following the standard curing process can avoid the problem of insufficient bonding caused by incomplete curing.

Room termperature curing polysilazane, pls check IOTA 9150, IOTA 9150K.          
High termperature curing polysilazane, pls check IOTA 9108, IOTA 9118.