Development of uniform and porous Al coatings on FeCrAl substrate by electrophoretic deposition

Uniform and porous Al coatings on FeCrAl substrate were prepared using an efficient electrophoretic deposition (EPD) in absolute ethanol suspension. The zeta potential and viscosity of suspension were measured to determine the optimal AlCl3·6H2O concentration for deposition. The most homogeneous coatings were obtained with 0.5 mM AlCl3·6H2O as the electrolyte. The effects of applied voltage and deposition time on deposition rate and coating morphology were also investigated. Uniform coatings could be obtained by EPD at 30 V within 2 min. By characterizing the Al deposition kinetics, it was found that the deposition rate was mainly determined by the current density after initial deposition period. A porosity equation was also proposed, indicating that the porosity of uniform coatings could be easily manipulated by deposition voltage. In this way, different Al coatings can be designed and prepared by EPD according to the practical requirement.