Effect of Al2O3 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+ Al2O3) coating. Sn-4% Zn alloy/nanoparticle composite (NiO+ Al2O3) 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 Al2O3 and both NiO and Al2O3 nanoparticle combined additions in the Sn-Zn coating. The maximum coating thickness of 70 +/- 1.8 mu m was achieved for Al2O3 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 mu m was achieved for Al2O3 nanoparticles in the Sn-Zn coating. Polarization and impedance measurements were used to investigate the influence of the incorporated Al2O3, NiO, and hybrid Al2O3/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 Al2O3, NiO, and Al2O3/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: Al2O3/NiO > NiO > Al2O3.