1.What effect does the zinc flower structure have on the corrosion resistance of the coating itself?
Large zinc flowers: The grain size is large (usually greater than 1mm), there are tiny grain boundary gaps between flowers, and the surface flatness is low (may be accompanied by slight convexities or depressions). These gaps and unevenness may become weak points for the penetration of corrosive media (such as moisture and salt). When exposed to a humid or highly corrosive environment for a long time, the electrochemical corrosion of the zinc layer may occur preferentially from the grain boundaries, slightly accelerating the consumption of the zinc layer.
Small zinc flowers: The grain size is small (usually less than 0.5mm), the crystallization is denser, the grain boundary gap is small, and the surface is smoother. This structure can reduce the penetration path of the corrosive medium, the overall uniformity of the zinc layer is better, and its own corrosion resistance is slightly better than that of large zinc flowers.
2.What effect does the size of zinc spangles have on coating adhesion?
Large zinc flower: The surface is uneven (tiny points may form at the protrusions of the zinc flower). The coating may have tiny pores at these locations due to uneven thickness or stress concentration. After long-term use, the coating is easy to peel off from the protrusions, resulting in direct exposure of the zinc layer and accelerated corrosion.
Small zinc flower: The surface is smooth and flat, the coating can be covered more evenly, the adhesion is stronger, the physical barrier effect is more stable, and the corrosion risk caused by coating damage is reduced.
3.What is the difference between large zinc flowers and small zinc flowers in practical applications?
Small zinc flowers have more stable corrosion resistance and slightly longer service life due to their surface density and coating adhesion. Large zinc flowers can make up for some of their defects if they are properly treated (such as passivation and oiling), but their overall corrosion resistance is still slightly inferior to that of small zinc flowers.
4.Which one is more rust-resistant, small zinc flowers or large zinc flowers?
The surface grains of the small zinc flower coating are small and dense. This structure makes the contact area between the zinc layer and the air relatively small, and the oxidation rate is slower, which can better resist the erosion of the zinc layer by the external corrosive medium, thereby protecting the steel base. At the same time, the plasticity and adhesion of the small zinc flower coating are very good, and the corrosion resistance before and after deformation remains unchanged. Its atmospheric corrosion resistance is 2-3 times that of conventional hot-dip galvanized sheets.
The zinc flower size of the large zinc flower coating is larger, and the surface is relatively less dense. Under the same environment, it is easier to react with the corrosive medium, and the rust resistance is relatively weak.
5.Will the color coated coil fade under strong sunlight on plateau?
Color-coated coils may fade under strong sunlight in plateau environments.
The fading of color-coated coils is mainly due to the decomposition of pigments and resins in the paint under long-term ultraviolet radiation. The long sunshine hours and high ultraviolet intensity in plateau areas will accelerate the decomposition of pigments and resins, making color-coated coils more prone to fading.