Application of Zinc Dust in Galvanization
The DACRO process is a corrosion-resistant coating technology that has been adopted domestically in recent years. The coating thickness is generally between 5 to 10 μm. The anti-rust mechanism involves the controlled electrochemical barrier protection provided by zinc to the substrate, the passivation effect of chromate, the mechanical shielding cover provided by zinc sheets, aluminum sheets, and composite chromate coatings, as well as the “anodic” effect of aluminum inhibiting zinc.
Compared to traditional electro-galvanizing, zinc-chromate coatings exhibit exceptionally strong corrosion resistance, being 7 to 10 times more resistant than electro-galvanized coatings. It does not suffer from hydrogen embrittlement, making it particularly suitable for high-strength components. Additionally, it features high heat resistance (temperature tolerance of up to 300°C).
Process Flow for Zinc-Chromate Coating Technology:
Organic solvent degreasing → Mechanical polishing → Spraying → Spinning dry → Drying (60-80°C, 10-30 min) → Secondary spraying → Sintering (280-300°C, 15-30 min) → Drying.
Furthermore, this technology is pollution-free during the coating process, marking a revolution in the history of metal surface treatment. It represents a cutting-edge technology in the field of metal surface treatment worldwide today, especially suitable for automotive and motorcycle chassis, engine components, and high-strength components in elastic and tubular structures. The coating exhibits high permeability, high adhesion, excellent wear resistance, high weather resistance, high chemical stability, and pollution-free characteristics.
The appearance of the DACRO coating solution is a uniform silver-gray color. The coating solution, after undergoing the aforementioned process and being baked at around 300°C, generates amorphous composite chromate compounds that cover the surface of the substrate as well as the surfaces of the zinc and aluminum sheets, tightly bonding them to the steel substrate. The spaces between the zinc and aluminum sheets are also filled with composite chromate, resulting in a thin silver-gray DACRO special corrosion-resistant coating upon cooling.
Advantages of Mechanical Galvanization
The process is simple to operate, has low energy consumption, provides good surface brightness, and is more cost-effective in industrial processing compared to DACRO treatment.
The galvanized coatings applied to outdoor fasteners for long-term corrosion resistance rely on the sacrificial anode properties of zinc. Therefore, the coating must contain sufficient zinc to ensure that outdoor fasteners possess decades of corrosion protection.
In long-term practice, regardless of the type of modern corrosion-resistant technology employed, the essence of preventing or slowing metal corrosion lies in disrupting the conditions necessary for corrosion formation or slowing the rate of the electrochemical corrosion process. The properties of zinc powder make it an important corrosion-resistant material, leading to its widespread application.
China possesses relatively rich resources of lead-zinc ores. In recent years, the development and application of zinc dust preparation and corrosion-resistant technologies, as well as the formulation of heavy-duty anti-corrosion coatings using materials such as organic silicon, fluorocarbon, rare earth elements, and graphene, have contributed to the reduction of non-renewable resource consumption while providing new corrosion resistance technologies and materials for protective applications.
Post time: Feb-11-2025
