Cold-Sprayed Nanostructured Pure Cobalt Coatings

Cold-sprayed pure cobalt coatings were deposited on carbon-steel substrate. Submicrometer particles for spraying were produced via cryomilling. Deposits were produced using different processing conditions (gas temperature and pressure, nozzle-to-substrate distance) to evaluate the resulting variations in grain size dimension, microhardness, adhesion strength, and porosity. The coating mechanical properties improved greatly with higher temperature and carrying-gas pressure. The coating microstructure was analyzed as a function of spraying condition by transmission electron microscopy (TEM) observations, revealing many different microstructural features for coatings experiencing low or high strain rates during deposition.