Development of Nanoporous Alumina Catalyst Support by Anodic Oxidation of Thermally and Kinetically Sprayed Aluminum Coatings

Abstract

Of the various catalyst supports that have been developed, nanoporous alumina prepared by anodic oxidation of aluminum layers has attracted particular interest because of its extremely high specific area, easy controllability of porosity, coating thickness, and high bond strength with substrates. In the present study, kinetic- and plasma-spraying methods are employed to deposit aluminum, and the effect of the deposition method on the nanopore density after anodic oxidation is examined through scanning electron microscopy, transmission electron microscopy, and electron backscatter diffraction observations. It is found that nanopore densities in the kinetically sprayed aluminum layers are much denser than in plasma-sprayed layers. It is hypothesized that this is attributed to the dense dislocation because of large internal stress during the deposition process.