Decisive influence of colloidal suspension conductivity during electrophoretic impregnation of porous anodic film supported on 1050 aluminium substrate

•Deposition kinetic depends on the suspension conductivity.•For low dispersion conductivities, deposition is controlled by particle diffusion.•When conductivities are high the forming deposit resistance governs the deposition kinetic.•For high conductivities, the electric field is focused on the anodic film. The present paper studies the influence of suspension conductivity on the electrophoretic deposition (EPD) of nanoparticles inside a porous anodic aluminium oxide film. It is shown that an increase in the suspension’s conductivity enhances impregnation of the anodic film by the nanoparticles. Two mechanisms are seen to promote the migration of particles into the pores. Indeed an increase in the suspension conductivity leads on the one hand to a strengthening of the electric field in the anodic film and on the other hand to a thinning of the electric double layer on the pore walls. The results of our study confirm that colloidal suspension conductivity is a key parameter governing the electrophoretic impregnation depth.