Effect of Al 2 O 3 and NiO Nanoparticle Additions on the Structure and Corrosion Behavior of Sn—4% Zn Alloy Coating Carbon Steel

The application of a higher corrosion resistance coating modified with nano additions can effectively decrease or prevent corrosion from occurring. In the present work, a novel method is successfully developed for the modification of carbon steel surfaces aiming for high corrosion resistance using Sn—4% Zn alloy/nanoparticle composite (NiO+ Al 2 O 3 ) coating. Sn—4% Zn alloy/nanoparticle composite (NiO+ Al 2 O 3 ) coatings were deposed on carbon steel using a direct tinning process that involved a power mixture of Sn—4% Zn alloy along with a flux mixture. Regular coating and interface structures were achieved by individual Al 2 O 3 and both NiO and Al 2 O 3 nanoparticle combined additions in the Sn-Zn coating. The maximum coating thickness of 70 ± 1.8 µm was achieved for Al 2 O 3 nanoparticles in the Sn-Zn coating. Interfacial intermetallic layer thickness decreased with all used nanoparticle additions in individual and hybrid conditions. The minimum intermetallic layer thickness of about 2.29 ± 0.28 µm was achieved for Al 2 O 3 nanoparticles in the Sn—Zn coating. Polarization and impedance measurements were used to investigate the influence of the incorporated Al 2 O 3 , NiO, and hybrid Al 2 O 3 /NiO nanoparticles on the passivation of the low-carbon steel (LCS) corrosion and the coated Sn—Zn LCS in sodium chloride solution. It was found that the presence of Al 2 O 3 , NiO, and Al 2 O 3 /NiO nanoparticles remarkably improved the corrosion resistance. The corrosion measurements confirmed that the corrosion resistance of the coated Sn-Zn carbon steel was increased in the presence of these nanoparticles in the following order: Al 2 O 3 /NiO > NiO > Al 2 O 3 .