Effect of Powder Morphology on the Cold Spray Properties of Tantalum

This study investigated the effect of the powder morphology, during cold spraying of Tantalum coatings. In all conditions, the gas temperature and pressure were attuned to attain similar particle velocities for spherical, irregular and mixed (irregular + spherical) morphology conditions. Coatings were characterized via optical and electron microscopy techniques. Deposition efficiency, coating microhardness, and porosity were evaluated for all conditions. Results show that for the same process conditions, the deposition efficiency and coating density were mostly the function of the powder velocity, which in turn was influenced by powder morphology. Hence, for the same process conditions, irregular particles can achieve higher velocity compared to spherical particles due to their higher drag coefficient. In this regard, the differences between the particle morphology and coating parameters are discussed.

Keywords: Drag Coefficient, Cold Sprayability, Particle Morphology, Particle Size Distribution, Particle Velocity, Tantalum