Solid Particle Erosion Processes in Coatings and Composite Materials

Solid particle impingement erosion of uncoated composite materials of quartz-polyimide, glass-epoxy and quartz-polybutadiene constructions and of three protective coatings; a hard MIL-C-83286 polyurethane, an elastomeric AF-C-VBW-15-15 fluorocarbon, has been investigated utilizing natural Mediterranean Sea sand. Environmental parameters of impact angle (15 to 90) and sand weight impacted (200, 400 and 600 g) have been examined and materials response was characterized by weight loss, surface roughness and surface morphology. The erosion process in these composites consisted of the following sequence: erosion and local material removal in the resin zones; erosion in the fiber zones associated with breakage of fibers due to bending failure of unsupported sections where resin beneath had been removed; and erosion of the interface zones between the fibers and the adjacent matrix. In all coatings investigated, erosion rate (i.e., target weight loss) decreased with the increase of the impact angle. Maximum weight loss was found at 30 deg while minimum value of weight loss was found at normal impact angle. However, in elastomeric MIL-C-83231 polyurethane and AF-C-VBW-15-15 fluorocarbon coatings, erosion rate was found to be independent of impact angle at the range of 45 to 90 deg.