Effects of process parameters on deposition behavior and mechanical properties of alumina coatings by aerosol deposition

As a novel coating spray technique, the aerosol deposition method is applied for the fabrication of dense, nanostructured ceramic coatings at room temperature via an impact consolidation mechanism. It is widely recognized that the successful deposition of coatings is strongly dependent on processing parameters during the deposition process. In this study, a brush-type aerosol generator was employed to enhance the continuity and stability of the aerosol supply. The uniformity of powder consumption at different packing densities was evaluated; an optimal loading density of 33% was identified for the alumina powders used in this study. Both simulation and experimental studies were performed to investigate the influence of gas flow rate and standoff distance (SoD) on coating fabrication and properties. The predicted particle impact velocity increased with increasing gas flow intensity and SoD, resulting in enhanced mechanical properties of the coatings, including adhesive strength and hardness. The maximum compressive residual stress value of 389 MPa was determined for an alumina coating fabricated at a gas flow rate of 20 L/min.