LAFAD Hard Ceramic and Cermet Coatings for Erosion Protection of Turbomachinery Components

Abstract

To mitigate costly surface damage, compressor blades are coated with materials that resist corrosion and resist wear from particle impact. Large Area Filtered Arc Deposition (LAFAD) technology has demonstrated the capability of depositing relatively thick cermet coatings with microlaminated architectures forming a stack of metallic/ceramic bi-layers. These coatings have nearly defect-free morphology and an extremely smooth surface with high surface energy, which improves the aerodynamics of airfoils. Yet, the deposition process can be carried out at a speed that produces coatings sufficiently thick to provide long life protection from particle damage at a cost-effective production rate. The basic mechanical properties and erosion resistance of LAFAD microlaminated cermet coatings deposited on Ti6Al4V and 17-4PH steel substrates have been investigated as a function of coating composition and architecture.