Anti-corrosion Behaviors of Polyurea Coating in Acid, Alkali and Salt Solution

The anti-corrosion behaviors of a polyurea coating were studied by seawater immersion, salt spray test, acid immersion and alkali immersion tests. The surface morphology of the coating was observed by scanning electron microscopy (SEM). The results indicated that the tensile strength decreased only 4% and the breaking elongation increased 1.2% when immersed in seawater for 180d. The tensile strength decreased 25.7%, the elongation increased 4.2%. and some part of the coating was corroded, but its structure remained in densification when exposed in salt fog for 180d. The tensile strength dropped 30%, the breaking elongation increased 1.1%, the surface of the coating was corroded seriously, and the corrosion was expanded to the interior, formed many degradation products, and the morphology changed severely when immersed in 10% sulfuric acid solution for 60d. The tensile strength decreased 25%, the elongation increased 9.6%, and the surface roughness increased, but internal structure was intact when immersed in 15% sodium hydroxide solution. It is suggested that the polyurea coating has good resistance to seawater immersion and salt fog corrosion, but the corrosion resistance was lowered after immersing in acid and alkali solutions.