Abstract
Steel structures at Army installations must be protected from atmospheric corrosion.
Many commercially available coatings that have been used are subject to combined effect of exposure to sunlight, changing humidity, and hot and cold cycles experienced during weathering. In many cases, due to lack of maintenance, the paint has deteriorated, and has begun to peel. Also, in the past, lead-based paint was used as a primer for the coating systems applied to these steel structures. Peeling lead-based paint will eventually fall into and contaminate the soil, and require extensive environmental cleanup.
Surface tolerant coatings, which can be applied over existing coatings with minimal surface preparation, provide a solution to these problems. Steel structures at an Army installation were chosen for application of these candidate coating systems. Two aircraft hangars and two deluge tanks (water tanks for fire suppression at the airfield) were overcoated with polyurethanes, which actually cure by reacting with moisture from the air. Critical areas of the deluge tanks were coated with self-healing coatings that contain microcapsules with film formers and corrosion inhibitors, which are released to repair the overcoating if it is damaged. Fluoropolymer coatings were applied over the existing paint on a flight control tower. The benefits of surface tolerant coatings are extension of service life, reduction in maintenance cost, elimination of the expense of removing hazardous lead coatings and preservation of appearance.
