Effect of spray powder particle size on the bionic hydrophobic structures and corrosion performance of Fe-based amorphous metallic coatings

Abstract

Fe-based amorphous metallic coatings (AMCs) with different spraying particle size powders were prepared on a 316 L stainless steel by the activated combustion high-velocity air fuel (AC-HVAF) method. The bionic hydrophobic structural characteristics and corrosion behavior of the AMCs after chemical etching and surface modification were studied by micro morphology observation and electrochemical testing. Results show that all AMCs have completely dense structure and a good combination with the 316 L stainless steel. In addition, the particle size shows a significant effect on the surface hydrophobic structure. The number of unmelted particles on the surface decreased with the decreasing particle size. As a result, micro/nanoscale hierarchical hydrophobic structures are constructed according to the Cassie–Baxter model, and an enhanced corrosion resistance is obtained given the particle size of 400 mesh. The TEM results showed that many nanoscale Cr-rich particles are randomly distributed in the AMCs. These Cr-rich particles built a nanoscale hydrophobic structure on the surface and improved the corrosion resistance of the AMCs. With the increase in the temperature and the concentration of the NaCl solution, the corrosion resistance of the hydrophobic AMCs decreased, and the water contact angle of the hydrophobic AMC with 400 mesh particle spraying powder reached 152.11°. Changing the particle size of spraying powder is an effective method to prepare the optimum bionic hydrophobic interfaces for AC-HVAF AMCs.