With increasingly stringent environmental regulations and limited resources, the coatings industry is moving towards water-based, powder, high-solids and light-curing. Among the many coatings, zinc-rich coatings have attracted attention for their excellent anti-corrosion properties.
Types of zinc-rich coatings
Zinc-rich coatings are mainly divided into inorganic zinc-rich coatings and organic zinc-rich coatings, and the former can be subdivided into solvent-based silicate coatings, water-based coatings and inorganic phosphate coatings.
Organic zinc-rich coating
Composition - epoxy resin as the base material, containing more than 80% zinc powder.
performance
Corrosion Resistance – Zinc powder galvanizes a galvanic couple with a steel base to provide sacrificial anodic protection.
Bonding strength - epoxy resin has a good combination with the steel base and is not easy to peel off.
Electrical conductivity – The high zinc powder content gives the coating good electrical conductivity and is suitable for spot welding.
Solvent-based silicate zinc-rich coating
Composition – based on the mixing of silicates (e.g. ethyl silicate) with metallic zinc powder.
performance
Corrosion resistance – effective corrosion protection through isolation shielding and sacrificial anodic protection.
Thermal stability – high temperature resistance up to 450°C.
Inorganic phosphate zinc-rich coating
Composition – a mixture of inorganic binders and zinc or aluminum.
performance
Corrosion resistance – can be used as an alternative to hot-dip galvanizing.
High temperature performance - can withstand high temperatures of 500-600°C for a long time.
Water-based inorganic zinc-rich coating
performance
Self-protection – a protective film is created when the coating is damaged, enhancing durability.
High temperature resistance - continuous temperature resistance up to 400°C, instantaneous high temperature up to 800°C.
Preparation and application of coatings
Pre-treatment - the surface of the substrate should be free of oil, rust, etc., and meet the sandblasting treatment standard (such as Sa2.5 grade).
Ingredients – Formulated in prescribed proportions to maintain a homogeneous mix to ensure coating performance.
Construction conditions - the relative humidity should be lower than 85%, the temperature should be higher than 5 °C, and the thickness of a spraying should generally be 100-150um.
Areas of application for zinc-rich coatings
Buildings and bridges, such as some bridges and TV towers in Beijing and Tianjin, are coated with water-based inorganic zinc-rich coatings.
Ships & Offshore Structures – Offshore drilling platforms, coastal installations, and other structures that need to be corrosion-resistant.
High-purity gas storage tank - water-based inorganic zinc-rich coating can effectively protect the inner wall of high-purity nitrogen storage tank and avoid contamination by organic components.
conclusion
Zinc-rich coatings have gradually become a popular choice in the coatings market due to their excellent anti-corrosion properties and environmental protection properties. With the advancement of technology and the expansion of the application range, zinc-rich coatings will play a more important role in the coatings industry in the future. Its good corrosion resistance, high temperature resistance and self-protection characteristics make it have great potential for development in various industrial applications.
