Development of Aluminum Coated Steet Made by New Powder Coating Method

Abstract

An improved powder coating process to make a pure aluminum coated steel sheet has been developed by using a continuous pilot production line. This process is composed of preliminary coating of thin zinc layer, coating of aqueous slurry of aluminum powder, light rolling and heating at 500600°C. Preliminaly zinc coating of 0.03 to 0.1 μm thick is found to be very effective to improve the adhesion of aluminum film on the final product. By applying this method, it also becomes possible to add some special thickeners into aqueous slurry of aluminum powder, which strengthen the cohesive force of aluminum powder to base steel sheet during the coating process.
The product is characterized by pure aluminum coating up to 60 μm thick having attractive bright appearance, negligible pinholes in aluminum film, good film adhesion and excellent corrosion and heat resistance. The product can be bent tightly up to 180° and can be deep-drawn without exfoliation of coated aluminum. The surface of the product can be colored electrolytically just like as pure aluminum metal and also can be enameled.