Residual stresses arising during high-velocity oxyfuel (HVOF) spraying usually impose a limit on coating thickness. In this work, dry-ice blasting is used in combination with HVOF spraying to produce thick WC-Co coatings characterized by compact microstructure, crystal refinement, high hardness, and excellent sliding wear resistance.

In this work, alumina coatings are produced by atmospheric plasma spraying using dry-ice blasting to prepare substrate surfaces. Feedstock powder and coating microstructure are examined and dielectric strength and ac-dc breakdown voltages are measured. The results show that dry-ice blasting improves the dielectric properties of alumina coatings produced by atmospheric plasma spraying.

This study evaluates the effects of heat treating on the microstructure, phase composition, and friction and wear behavior of plasma sprayed FeAl coatings. Fe-40Al feedstock powder was deposited on mild steel substrates by atmospheric plasma spraying and the coatings were vacuum annealed at 500, 650, 900, and 1000 °C. An examination of coating cross-sections revealed the presence of diffusion layers in the samples treated at 900 and 1000 °C. XRD analysis indicates that annealing at 650°C facilitates the transformation of Fe(Al) solid solution into FeAl intermetallic phase, resulting in an increase in coating hardness. At higher temperatures, however, Al depletion occurs along with a reduction in hardness. Tribological testing showed that both the friction coefficient and the effects of wear increased after heat treatment.

Dry-ice blasting, as an environmental-friendly method, was used during atmospheric plasma spraying for improving coating properties. This process is believed to be capable to reduce the porosity and the oxide of the coating and to increase the deposition efficiency, etc. Considering dry-ice pellets are carried and accelerated by compressed air through a convergent-divergent nozzle, the computational fluid dynamic (CFD) approach was firstly employed in this study to evaluate the effects of nozzle geometry, accelerating gas conditions as well as properties of pellets, on the pellet velocity variation and further to optimize the process. Moreover, the experiment with a steel powder was then carried out and the results indicate that a denser coating with a lower content of oxide can be achieved with the application of dry-ice blasting during the plasma spraying.