Effect of Aluminum Anode Temperature on Growth Rate and Structure of Nanoporous Anodic Alumina

Abstract

In the present study, we investigated the effect of an anode temperature on current transient process during porous anodic alumina growth and morphology of the anodic layers. Alumina films were formed in a 0.4 M oxalic acid at a constant voltage mode and electrolyte temperature. The temperature of the Al anode was controlled by thermoelectric Peltier element and varied in the range of 5 °C–60 °C. Surface morphology of both sides of anodic films and their cross-sections were analyzed by scanning electron microscopy (SEM) with subsequent statistical analysis of the SEM images by ImageJ software. It was found that when anode temperature was increased from 5 °С to 50 °С the pores diameter and interpore distance has not changed, but the porous structure became more ordered. According to these results, the rate of chemical dissolution of the barrier layer and pore walls did not depend on the anode temperature. At the anode temperature of 60 °С, pores diameter has increased 1.7 times and there was a distortion of the ordering of porous cells. It was concluded that the temperature difference between the aluminum substrate and electrolyte is an important parameter affecting the formation of ordered structure of nanoporous anodic alumina.

Porous Alumina Films Fabricated by Reduced Temperature Sulfuric Acid Anodizing: Morphology, Composition and Volumetric Growth

“…This assumption is all the more valid, since the ref. [ 66 ] thoroughly demonstrates the influence of the electrolyte type and temperatures on the anodizing process characteristics and morphological parameters of the formed oxide.…”

Recent Advances in Nanoporous Anodic Alumina: Principles, Engineering, and Applications

“…Higher temperature is a convenient measure to accelerate the alumina growth and adjust the resultant pore diameter not affecting interpore distance simultaneously [ 93 , 94 ]. Evaluation how—independently of the electrolyte temperature—temperature of the aluminum anode can impact the formation of NAA was performed by Chernyakova et al [ 95 ]. For the temperature increase between 5 °C and 60 °C d p and d int remain unchanged, while structural ordering has increased.…”

Nanoporous Anodic Aluminum-Iron Oxide with a Tunable Band Gap Formed on the FeAl3 Intermetallic Phase

“…It should be noted that each attempt to carry out this process requires individual optimization of parameters for each type of substrate material. The parameters that determine the morphology of the anodic oxide produced include the type of aqueous or non-aqueous electrolyte solutions and their concentration and temperature as well as the potential and duration of the electrochemical anodization process [13]. Parameters that describe the geometry of nanostructured anodic oxides, include the average pore diameter, average distance between pore centers, thickness of the oxide coating, and thickness of the barrier layer, which separates the bottom of the resulting pores from the substrate material; this is especially true for anodic aluminum oxide, which is a typical material produced by anodization [14][15][16].…”