Development of Epoxy Based Surface Tolerant Coating Improvised with Zn Dust and MIO on Steel Surfaces

Couple of high strength and flexible surface tolerant coatings were designed for oil contaminated, rusty, and minimally prepared steel surfaces. These coatings are to have strong interfacial adhesion due to low surface tension and sustain more than 5？MPa pull out force consistently. The effect of optimized concentration of zinc dust and micaceous iron oxide (MIO) as pigments is evaluated for these surface tolerant coating systems. It has been noticed that the presence of these two ingredients has enhanced corrosion resistance more than several times as compared to commercially available coating systems. The corrosion simulation test in 3.5？wt.% NaCl has evident for significant improvement in terms of delaying blistering and delamination. The high pore resistance ( ) indicates the slow migration of ions and water into the substrate and coating interface, which could be the reason of the improvement in corrosion process. 1. Introduction Surface tolerant coatings are the coatings which can be applied over moist, chemically contaminated or rusty steel, old painted surface, and other minimally prepared surfaces. Most commonly used are red lead alkyd, epoxy mastic, aluminum epoxy mastic, moisture-cured urethane, coal tar mastic, modified wax, and grease based materials. The addition of zinc and micaceous iron oxide (MIO) in the binder provide the cathodic and barrier protection with an excellent surface tolerant tendency. The coating properties of a “fair” surface tolerant coating are excellent penetration, wettability, adherence ability under dry and wet conditions, high electrical resistance to provide a barrier between anodic and cathodic sites of corrosion cells, excellent barrier properties such as impermeability to water, oxygen, and ions, neutralization of chloride, bromide and sulfate salts, and ability to suppress internal stress. Surface tolerant coatings do not require high profile surface preparation so no generation of fine dust, abrasive particulates but abrasive blast cleaning, produces toxic debris and its disposal may be harmful. Surface tolerant coatings can be a replacement of high performance marine coatings systems (required a high degree of surface cleanliness). No cleanliness of high performance marine coating systems may cause the potential degradation of performance and reduction in durability of high performance corrosion control coating systems [1–3]. The surface tolerant coatings are mainly used as maintenance and anticorrosive property in marine and industrial environments. The challenge of reducing the level of surface