Structural characterisation of heat-treated anodic alumina membranes prepared using a simplified fabrication process

Fabrication, Structure and Properties of Nanostructured Ceramic Membranes

“…These events are irreversible and do not reappear in consecutive heating cycles of the same sample. The thermal analysis data reported by Kirchner et al (2007a) and Ozao et al (2001) are in good agreement. Decreasing the heating rate to 2 °C/min shifted the peak temperatures of the exotherms from 970 °C to 925 °C and from 1228 °C to 1157 °C, respectively, and resulted in a more pronounced endotherm at 930 °C.…”

“…To ensure that anodisation occurs on one side only one Al face is protected with epoxy or nail polish, which is subsequently stripped following the anodisation chemistry. One such methodology is as follows (Kirchner, 2007a) : Annealed high purity (99.99%) aluminium foil of 0.25 mm thickness (Alfa Aesar) was used as a starting material. Pieces 25 mm x 10 mm were degreased in acetone, coated on one side with ADR246 epoxy (Adhesive Technologies) and cured for 2 h at 80 °C.…”

“…To obtain free-standing membranes numerous methods have been reported to dissolve or detach the aluminium. In terms of dissolution methods, the use of HgCl 2 solutions, although effective, has generally been superseded by dissolution of the remaining aluminium metal in a saturated iodine-methanol (or ethanol) solution at 50ºC (Kirchner, 2007a). The transparent PAA membranes are rinsed in methanol to clean off excess iodine.…”

“…Typical instrument setup and operating conditions are described by Brown et al, (2006). Previously reported thermal analysis data (Brown et al, 2006;Kirchner et al, 2007aKirchner et al, , 2008 shows that further heating causes a sharp exothermic event due to formation of crystalline transition alumina phase(s temperature varies with sample heating rate. The thermal and structural characteristics of PAA prepared using these three acid electrolytes are markedly different and are explored in greater detail in the following sections.…”

“…PAA membranes can be produced using both so-called 'mild' and 'hard' anodizing techniques (Kirchner et al, 2007a;2008;Lee et al, 2006b;Brown et al, 2009). For mild anodisation (MA) the voltage is maintained at a minimal level compatible with obtaining alumina growth.…”