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Electrochemical modification of aluminium in oxalic acid as a tool for the design of microreactors based on Al-Al<inf>2</inf>O<inf>3</inf>

Abstract:

Electrochemical oxidation was studied using oxalic acid (1.6 M), varying some conditions, as: current density (Ia = 1-3 A/dm2), electrolytic bath temperature (Ta = 40-50 °C), anodizing time (ta = 40-100 min) and a post-anodizing treatment (PA) at different current densities (Ia = 1-3 A/dm2) with a constant post-anodizing time (tPA = 40 min) and increasing the treatment time (tPA = 0-120 min) at constant current density (Ia = 2 A/dm2). The variation of these conditions showed that the Al2O3 formation depends on two fundamental processes. First, it is the generation of an anodic oxide layer followed by its dissolution on internal and external surface of the pore. The influence of each variable on these two stages causes the generation of layers with texture and roughness specific characteristics. Similarly, it was demonstrated that independently of the geometric shape, a morphological equivalence of the anodic Al2O3 in the aluminum substrates was obtained. Furthermore, a trend in the pressure drops: MACL1100 > MAE40 > MAE20 > MAE10 > MACL350 was observed; this performance depends of the spatial distribution and cells number.