Abstract
It is well known that the corrosion of steel occurs by sea salt particle near seashore environment. However, it is not understood that the shape of sea salt particle and whether sea salt particle is the liquid or solid status when it attaches the steel. The morphology of attachment of sea salt particle has a large influence on corrosion of steel. It is very important to understand the morphology and composition of sea salt particle. The morphology and composition of sea salt particle was studied by using an AFM and an optical microscope under relative humidity control conditions. As the result, it was found that the sea salt particle attached the specimen with circular figure and that the thin liquid film of MgCl2 with thickness of 10nm existed. Small sea salt particles with diameter of 50nm were found around the big sea salt particle.