Thermal Spray Deposition and Evaluation of Low-Z Coatings

Thermally-sprayed low-Z coatings of boron carbide (B4C) on aluminum substrates were investigated as candidate materials for first-wall reactor protective surfaces. Comparisons were made to thermally-sprayed coatings of boron, MgAl204, Al2O3, and composites. Graded bond layers were applied to mitigate coefficient of thermal expansion mismatch. Microstructures, thermal diffusivity before and after thermal shock loading, steel ball impact resistance, CO2 pellet cleaning and erosion tolerance, phase content, stoichiometry by Rutherford backscattering spectroscopy (RBS), and relative tensile strengths were measured.