Improving the hardness of coatings can be approached from multiple aspects such as coating material selection, preparation process optimization, and post-treatment. The following are specific methods:
Material selection and formula design
Select high hardness fillers
Ceramic fillers: such as alumina (Al ₂ O ∝), silicon carbide (SiC), boron nitride (BN), etc. These ceramic materials themselves have high hardness, and adding them to the coating with appropriate particle size and proportion can significantly improve the hardness of the coating. For example, adding nano-sized alumina particles to metal based coatings can effectively enhance the wear resistance and hardness performance of the coating.
Hard mineral fillers: such as quartz powder, diamond micro powder, etc. Quartz powder has stable chemical properties and high hardness, which can increase the wear resistance of coatings; Diamond is the hardest known substance, and adding a small amount of diamond micro powder can greatly improve the hardness of the coating, but the cost is relatively high.
Optimize resin system
Choose high crosslink density resins such as phenolic resins, epoxy resins, etc., and form a highly crosslinked structure through reasonable curing agents and curing processes. High cross-linking density means that the connections between molecular chains are tighter, which can effectively resist external deformation and improve the hardness of the coating. For example, by using multifunctional epoxy resins and corresponding curing agents, coatings with high cross-linking density can be obtained.
Resin modification: Chemical modification can be used to introduce rigid groups or enhance intermolecular forces on the resin molecular chain. Introducing rigid structures such as benzene rings into silicone resins can improve their hardness and thermal stability.
Preparation process control
Adjusting coating thickness: Within a certain range, increasing the coating thickness appropriately can improve the overall hardness of the coating. Thicker coatings can better withstand external impact and disperse stress. However, excessive coating thickness may lead to increased internal stress and cracking, so it is necessary to choose the appropriate coating thickness according to the specific situation.
Optimize coating process
Improve coating uniformity: Advanced coating techniques such as spray coating, electrophoretic coating, etc. are used to ensure uniform distribution of the coating. A uniform coating can avoid hardness differences caused by uneven local thickness or defects, making the entire coating surface consistent in hardness.
Controlling coating speed and pressure: Reasonable control of coating speed and pressure during the coating process helps to better bond the coating with the substrate and make the internal structure of the coating denser, thereby improving hardness. For example, in the spraying process, adjusting the pressure and movement speed of the spray gun appropriately can achieve high-quality coatings.
Precise control of curing conditions
Temperature and Time: Different coating materials have their optimal curing temperature and time range. Curing at an appropriate temperature can fully crosslink the resin and form a stable structure. For example, for certain thermosetting coatings, short-term curing at high temperatures may result in rapid surface curing and insufficient internal cross-linking, affecting hardness. Therefore, precise control of curing temperature and time is required.
Curing atmosphere: Some coatings can increase hardness when cured in a specific atmosphere. Curing in a nitrogen atmosphere can prevent coating oxidation and ensure stable coating performance; For some photosensitive coatings, curing under appropriate light intensity and time can fully utilize the photoinitiator and promote resin cross-linking.
Post processing methods
Heat treatment: Proper heat treatment of the coating can further improve its hardness. By heating, the molecular chains in the coating will undergo rearrangement and further cross-linking, making the coating structure denser. For example, after high-temperature sintering, the hardness of ceramic coatings will significantly increase. But the temperature and time of heat treatment need to be strictly controlled to avoid damage to the coating and substrate.
surface treatment
Chemical treatment: Using chemical reagents to treat the surface of the coating, such as silane treatment, phosphating treatment, etc., can form a hard protective film on the surface of the coating, improving surface hardness and wear resistance.
Physical treatment: such as using physical methods such as ion implantation and laser treatment to modify the surface of the coating. Ion implantation can inject high hardness ions onto the surface of coatings, changing the chemical composition and structure of the surface and improving hardness; Laser processing can rapidly melt and solidify the coating surface, forming a fine grain structure, thereby improving hardness.

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