조선·해양 기자재용 강재의 내식성에 미치는 분체도장 중 산화물 첨가의 영향

The demand for powder-coated steel used in the marine industry is increasing owing to their superior corrosion resistance. However, the powder coatings used in commercial products can deteriorate easily by the penetration of brine. In an attempt to suppress brine penetration into the powder coating and significantly increase the corrosion resistance, three types of oxide particles were added to the coating. Electrochemical impedance spectroscopy tests in 3.5% NaCl solution were performed to evaluate the corrosion behaviors of the powder coating with oxide particles. The results showed that the addition of SiO 2 particles to a powder coating severely decreased the corrosion resistance due to the easy detachment of agglomerated SiO 2 particles with a coarse size from the coating layer. In contrast, the TiO 2 and SnO 2 -added coatings showed better corrosion resistance, and the TiO 2 -added coating performed best in the test conducted at room temperature. However, conflicting results were obtained from tests conducted at a higher temperature, which may be attributed to the effective suppression of brine penetration by the fine SnO 2 particles uniformly distributed in the coating.