Laser Fusion Coatings of Functional Parts

Surface characteristics of functional parts made by Solid Freeform Fabrication techniques such as Selective Laser Sintering (SLS), Stereolitography Apparatus (SLA) or other fabrication techniques can be enhanced by the application of multi-element based laser fused coatings. Environmental protection and wear resistance, among other properties can be achieved by pre-depositing a slurry over the surface of the parts, followed by a high-speed scanning with a high power laser beam. Wetting of the part surface by the molten slurry is a main concern in this coating process. Wetting characteristics of molten slurry can be improved by the right combination of coating constituents, laser processing atmosphere, and laser processing parameters. Coating quality is also a critical issue to ensure good performance of the coatings especially for environmental protection. This paper presents results obtained for carbon-carbon composites coated with silicon-based slurries by laser fusion process. Criterion in selecting the coating constituents, laser process conditions, and oxidation test results are discussed.