2008 Volume 20 Issue 3 Pages 141-145
Coated steel sheets for exterior deteriorates with the combination of degradation of surface coatings by ultraviolet ray and heat and the corrosion of underneath steel sheets by water, salt, and cycles of dryness and moisture. In order to create the deterioration artificially, new cyclic-weathering test apparatus was invented. The apparatus repeatedly makes salt spray, wetting and ultraviolet ray irradiation with metal-halide lamp. Using the result of the cyclic weathering test, appropriate test conditions and evaluation items were determined. Then, according to the test conditions and evaluation items, five kinds of coated steel sheets for housing were tested. Each coated steel has different platting and paint. FinalIy, based on these results, we estimated the conditions of coated steel sheets used as roof sheets for 15 years and 30 years, and considered necessary measures such as re-painting.
