Due to the toxicity of hexavalent chromium in zinc-chromium coatings, countries around the world are gradually stopping the production and use of chromium-containing coatings. The chromium-free zinc-aluminum coating technology is a new type of “green” surface treatment technology. It is a novel zinc-aluminum coating that performs well and meets environmental protection requirements, making it a trend to replace zinc-chromium coatings. The production of chromium-free zinc-aluminum coatings requires various raw materials, with flake zinc powder being the most important one.
Zinc | A silver-gray metal with a metallic luster on the cross-section, which forms a dense layer of zinc carbonate film on its surface at room temperature, providing protective effects. The melting point of zinc is 419.8°C, and its density is 701 g/m³. At room temperature, it is relatively brittle, softening at 100-150°C and becoming brittle again at temperatures above 200°C. Zinc has three crystalline states: α, β, and γ, with transformation temperatures of 170°C and 330°C. The electrical conductivity of zinc is 27.8% that of silver, and its thermal conductivity is 24.3% that of silver.
Types of Zinc Dust
According to shape and application, zinc powder can be categorized into spherical zinc powder, flake zinc powder, and battery-grade zinc powder. Different production methods can yield zinc powders of various shapes, compositions, and applications.
Most metallic pigments use flake metal dusts. Flake zinc dust is formulated into coatings and then applied. The coating forms a film on the substrate surface, where the flake metal dust aligns in parallel layers with the coating surface, creating a shielding effect. Due to its unique two-dimensional planar structure, flake zinc dust exhibits good coverage, adhesion, reflectivity, and a large aspect ratio (50-200).
Optical Properties | Most metallic powders possess good optical properties, one of which is light-reflecting ability. For example, zinc-aluminum coatings exhibit a metallic luster effect.
Shielding Properties | When flake zinc dust is formulated into coatings and applied to form a film, the flake metal dusts align in parallel layers with the coating surface, generating a shielding effect.
Floating Properties | Another significant characteristic of flake zinc dust is its ability to float, allowing it to remain on the surface of the carrier material.
Special Properties | Due to its unique two-dimensional planar structure, flake zinc dist has excellent coverage, adhesion, significant shielding effects, and reflectivity, along with outstanding corrosion resistance.
Post time: Feb-12-2025
