Abstract
Coldspray is becoming a consolidated technology in deposition of several metallic coatings such as aluminium, titanium, nickel, copper and their alloys. However, increasing attention is paid to the capabilities of coldspray to deposit composite Cer-Met coatings starting from powders blends. High ceramic content coatings are difficult to get by Cold-Spray technique due to the low ductility of the ceramic phase, but as for metal coatings the low deposition temperature reduce the residual stresses, coating porosity and oxidation. Furthermore, using powder blends, obtained by quickly mixing the pure components, leads to a great versatility on materials usable for deposition. In present work, the influence of alumina content on coldspray deposition of Ni-Al2O3 coatings was studied. Five different powder blends were prepared, the ceramic content was set as 10, 25, 50, 75 and 90 weight percent of alumina. Ni-pure coatings have been prepared and compared with composites coatings. Characterization techniques were employed in order to determine the coating morphology and microstructure , with special attention to determine the real alumina content in the coating with respect to initial powder feedstock. The final coating porosity and the matrix hardness were also evaluated. Finally, the performance of the coatings in terms of oxidation resistance was determined and discussed.
