Electrophoretic Deposition of Aluminum Particles and Control of the Coating Microstructure

Electrophoretic deposition (EPD) is an efficient process for the elaboration of homogeneous thickness and tunable microstructure coating on conductive substrates [1]. EPD displays several advantages such as a low operating cost, a relatively simple equipment and the ability to plate uniformly onto complex shape parts [1]. Among all studies on electrophoretic deposition, metallic particles are widely less investigated than ceramic ones. However metallic materials offer interesting properties (optics, catalysis, etc.). The use of alcoholic media is widely advantageous for electrophoretic deposition process because a significant voltage range can be investigated while avoiding water electrolysis and bubbles formation. Moreover, as some metals present high reactivity towards aqueous media, the choice of alcohols as dispersing media looks appropriated. Electrophoretic deposition of an aluminum powder was performed in different alcoholic media: ethanol and propan-2-ol. The nature of the dispersing medium appears to strongly influence the process deposition. Direct EPD from pure ethanol suspension is not convenient [2] whereas deposition from propan-2-ol medium leads to an homogenous coating (Figure 1). Nevertheless, addition of ionic species into the ethanol suspension allows an increase of the number of aluminum particles deposited. The addition of these species also lead the formation of homogenous thickness coating up to 100 µm. The influence of the key parameters (relative to the suspension and the electrophoretic process) has been investigated in relationship to the coatings thickness and the microstructure.Keywords: electrophoretic deposition, aluminum, coating, microstructure.Figure 1: FIB-prepared cross-section of Al coating deposited under 10 V.cm-1 during 10 min from propan-2-ol suspension.References:1. L. Besra and M. Liu, "A review on fundamentals and applications of electrophoretic deposition (EPD)," Prog. Mater. Sci., vol. 52, no. 1, pp. 1–61, 2007.2. K. S. Yang, Z. Jiang, and J. S. Chung, "Electrophoretically Al-coated wire mesh and its application for catalytic oxidation of 1,2-dichlorobenzene," Surf. Coatings Technol., vol. 168, no. 2–3, pp. 103–110, 2003.Figure 1