Effects of Al-based alloy powders on the mechanical behavior, corrosion resistance and infrared emissivity of polyurethane composite coatings

Abstract Aluminum (Al)-based amorphous alloys (hereinafter abbreviated as AAA) with good mechanical and anti-corrosion properties are ideal fillers for modified organic coatings. A novel polyurethane (PU)/Al/AAA composite coating was prepared by adding Al-based alloy powders, which were composed of Al and AAA powders. The effects of Al or AAA powder concentration on the mechanical behavior, corrosion resistance and infrared (IR) emissivity of PU/Al/AAA coatings were systematically investigated and compared with those of PU/Al coatings. The AAA particles surrounded by Al flakes form annular structures in the polymer matrix. With the increase of AAA powder concentration, the hardness, IR emissivity, wear resistance and anti-corrosion of the PU/Al/AAA coating are increased, whereas the adhesion strength is slightly decreased. Moreover, excess AAA powder has a negative effect on wear and corrosion resistance of the coating. The optimal AAA powder proportion in the filler was found to be 57 wt%, resulting in a composite coating with good mechanical and anti-corrosion properties as well as low IR emissivity. The AAA powder developed by this work can serve as a good modified filler for high-performance PU coatings.