Ultrafine powder coating: Smooth surface, dense structure and enhanced corrosion resistance

In recent years, powder coatings are capturing more of the liquid coatings market due to their economical, ecological, environmental, and energy-saving benefits, yet their low surface qualities still hinder their wider application. In this study, ultrafine powder coatings (∼22 µm in size) were fabricated and compared with coarse powder coatings (∼35 µm in size) in terms of particles deposition during spray, leveling of coating powder during curing, and surface qualities, inner structures, and anti-corrosive properties of the obtained coating films. The results show that the ultrafine particles pack more loosely and uniformly during spraying with smaller average air pockets and level and degas faster during curing than their coarse counterparts. These characters lead the ultrafine powder to demonstrate lower surface roughness, higher gloss, fewer inner voids, and higher corrosion resistance. The significant increase in corrosion performance is exhibited through high barrier properties and narrow salt spray creepage. This study contributes not only to the in-depth understanding of how particle size affects coating film structure and properties, such as gloss, surface roughness and corrosion protection, but also to the promotion of powder coating technology in broader fields such as electronics and automotive industries.