MMCs Coatings with High SiC Volume Fraction Retention by Pulsed-Gas Dynamic Spraying

Aluminum-based composite coatings reinforced with different volume fractions of SiC particles were deposited on aluminum substrates by means of pulsed gas dynamic spraying using a mechanically mixed composite feedstock powder. Microstructural features of the coatings are examined and their hardness is reported. The results show that the high fraction of SiC particles in the feedstock powder are retained in the coatings and that increasing SiC content in the aluminum matrix significantly improves coating hardness. The highest hardness value was obtained for a coating with 28 vol% SiC. Beyond that, coating hardness decreased, which is attributed to increasing porosity and decreasing cohesion between deposited aluminum-based particles.