Synthesization and characterization of hybrid ZnO-SiO2 nanoparticles for anti-corrosion nanocoating of medium carbon steel

Abstract

Numerous coating compositions were developed and yet most of them are incapable to overcome several limitations in adhesion and effectiveness as anti corrosion. This research aimed at developing a new and improved coating that employs of zinc oxide (ZnO) and silica (SiO2) nanoparticles as the agent for anticorrosion coating. This research was divided in two main phases; phase1, synthesis of ZnO-SiO2 nanoparticles by sol gel method and phase 2, preparation of coating sample. ZnO was selected due to its special characteristics such as anti-corrosion, anti-bacteria and excellent heat resistance, while SiO2 was used to increase the consistency of coatings, giving good adhesion and low-cost flatting agents. These coatings were formulated through copolymerization of epoxy resin with the incorporation of ZnO and SiO2 nanoparticles. ZnO and SiO2 were synthesized using sol-gel method. Epoxy acted as host while the nanoparticles incorporate as guest components. The coating was directly applied onto carbon steel type S50C as the substrate. The tests of adhesion, immersion, UV, humidity and salt spray were carried out in accordance to ASTM D3359, B895, D4587, D2247 and B117-94 respectively. The results of FESEM and nano-particle size analyzer showed that the SiO2 and ZnO nanoparticles were successfully synthesized with the range sizes of 79.68 nm to 87.35 nm and the 81.28nm to 84.98nm respectively. Based on thermal analysis, contribution of nanoparticles possessed better thermal stability. Nanoparticles improved the quality of the cured epoxy coating, reduced the porosity of the coating matrix and improved barrier performance of the epoxy coating. Nanocoatings having good adhesion with the substrate in NaOH, H2O and HCl medium, formed hydrophobic surface for deionized water dropping and can withstand long protection from corrosion process in salt spray testing. Nanocoating demonstrates good anticorrosion behavior and good adhesion properties with significant thickness. Incorporation of 3 wt% of ZnO and 2 wt% of SiO2 nanoparticles were the best composition for nanocoating and produce novelty in improving coating properties.