Research and development direction of weathering steel

In the process of weathering resistant film treatment, the bottom layer is first treated with weathering resistant film, and inorganic composite salt film with composite phosphate as the main component is formed on the surface of weathering resistant steel. Then, the composite salt film is coated with acrylic coatings to form a porous grid coating with good air permeability and water permeability. The main function of the weather-resistant substrate is to form a uniform and dense stable rust layer on the surface of the weather-resistant steel. The upper porous grid coating film can allow a certain amount of air and water to supply the bottom layer until it forms a stable rust layer, and can prevent the flow and flying of the rust liquid in the early stage of use, and maintain the appearance of beauty. After the formation of the stabilizing rust layer, the coating gradually disappears, and the appearance no longer changes significantly. However, the time of change of the stabilized rust layer has a lot to do with the environment

(2) Special oxidation coating treatment (single or double layer). When the oxidation coating is treated, the hydrophobic color carrier is mixed with oxide pigments and additives that promote rust, and the organic film is formed on the surface of the weathering steel. Due to the action of this film, the rust liquid will not flow, and the organic film will disappear after the formation of a stable rust layer on the surface of the weathering steel. In the case of harsh environment, the influence of environment is mitigated by adding stable rust layer. The short exposure oxidation coating begins to transition to a stable rust layer after a few months, and the transition time of the long exposure oxidation coating takes about 1 to 2 years.

(3) Iron oxide and phosphate treatment (single or double layer). The iron oxide phosphate system is composed of primer and top paint, and the treatment process is the same as that of oxidation coating. The primer contains phosphoric acid (phosphate) or iron oxide, which has the effect of controlling early rust and forming a dense and stable rust layer