Durability of A588 Weathering Steel Coatings Applied by Thermal Spray Methods

A588 weathering steel is a high-strength low-alloy structural steel that has the ability to form a stable, rust-like appearance when exposed to the atmosphere, making it a popular choice for outdoor structures such as bridges and buildings. Despite its corrosion-resistant properties, A588 weathering steel still requires some form of protection to ensure its longevity.

One method of protecting A588 weathering steel is through the application of protective coatings using thermal spray methods. Thermal spray methods involve the use of a heat source to melt and atomize a feedstock material, which is then sprayed onto the surface of the steel substrate. The feedstock material can be a variety of materials, including metals, ceramics, and polymers, and can provide a range of properties such as corrosion resistance, wear resistance, and thermal insulation.

Several types of thermal spray methods are used for applying protective coatings to A588 weathering steel, including flame spraying, arc spraying, and plasma spraying. Flame spraying is the most commonly used method and involves the use of a high-velocity flame to melt and atomize the feedstock material, which is then sprayed onto the substrate. Arc spraying uses an electric arc to melt and atomize the feedstock material, while plasma spraying uses a plasma torch to melt and atomize the material.

The durability of A588 weathering steel coatings applied by thermal spray methods depends on various factors such as the type and quality of feedstock material, the thickness of the coating, the surface preparation of the substrate, and the environmental conditions to which the coating will be exposed. In general, thermal spray coatings have been found to be highly effective in protecting A588 weathering steel from corrosion and other forms of deterioration.

One study examined the durability of A588 weathering steel coatings applied by flame spraying using aluminum, zinc, and a combination of aluminum and zinc as feedstock materials. The coatings were applied to steel substrates with various surface preparations, including grit blasting and zinc phosphating. The coated substrates were exposed to a salt spray test and an outdoor exposure test for up to two years.

The results of the salt spray test showed that all three types of coatings provided excellent corrosion protection for A588 weathering steel. The combination of aluminum and zinc was found to be the most effective, providing more than 1200 hours of corrosion resistance before the first signs of rust appeared. The coatings also provided excellent adhesion to the substrate, with no signs of flaking or delamination.

The outdoor exposure test yielded similar results, with all three types of coatings providing excellent corrosion protection for up to two years. The combination of aluminum and zinc again proved to be the most effective, with no signs of rust or other forms of deterioration visible on the coated steel substrates.

Another study looked at the durability of A588 weathering steel coatings applied by plasma spraying using a chromium carbide feedstock material. The coatings were applied to steel substrates with a variety of surface preparations, including grit blasting and acid etching. The coated substrates were subjected to a salt spray test and a cyclic corrosion test for up to 1000 hours.

The results of the salt spray test showed that the plasma-sprayed chromium carbide coatings provided excellent corrosion protection for A588 weathering steel, with no signs of rust or other forms of deterioration visible on the coated steel substrates. The cyclic corrosion test also showed that the coatings provided excellent protection against saltwater corrosion, with no signs of corrosion or other forms of deterioration visible after 1000 hours.

In conclusion, A588 weathering steel coatings applied by thermal spray methods have been found to be highly effective in protecting the steel substrate from corrosion and other forms of deterioration. The type and quality of the feedstock material, the thickness of the coating, and the surface preparation of the substrate all play important roles in determining the durability of the coating. Properly applied thermal spray coatings can provide many years of protection for A588 weathering steel structures in outdoor environments.