Electrophoretic deposition of α-Al ₂ O ₃ -based coating as a hydrogen permeation barrier

Hydrogen embrittlement is a well-known surface-related phenomenon. Coating deposition using ceramic materials to resist hydrogen permeation is one of the promising solutions. This paper introduces an alternative wet deposition technique, namely electrophoretic deposition, to prepare aluminum oxide coatings onto metallic substrates. The main objective is to achieve compact alumina layers with as few pores and cracks as possible, showing good adhesion. The deposition of α-Al 2 O 3 coating has been chosen due to the low hydrogen permeability of this material. The coating properties were adjusted by controlling the process parameters. The use of microstructure characterisation techniques allowed to assess the quality of the coatings, and to understand the processes involved in coating formation. Results show that the coating quality can be significantly improved by using proper suspension formulation. The resulting optimised coating delivers a uniform and homogeneous α-Al 2 O 3 layer with low porosity and good adhesion to the substrate.