H. Terryn et al., CHARACTERIZATION OF ALUMINUM SURFACE TREATMENTS BY MEANS OF GAS-ADSORPTION MEASUREMENTS, Colloids and surfaces. A, Physicochemical and engineering aspects, 80(2-3), 1993, pp. 171-179
Adsorption measurements were used to determine the specific surface ar
ea of a.c. electrolytically grained aluminium and the porosity distrib
ution diagram of porous anodized aluminium. Alternating current electr
olytic graining of aluminium is used to increase the specific surface
area for the preparation of litho sheets or capacitor foil. The specif
ic surface area S (calculated by the BET procedure from the nitrogen a
dsorption isotherm) was studied as a function of the graining frequenc
y between 0. 1 and 1 000 Hz. The results were related to the graining
morphology by comparing them with scanning electron microscopy microgr
aphs. It is concluded that in contrast to the more common surface inve
stigation techniques the method can be used to measure quantitatively
the gain in surface area after such a treatment as a.c. electrolytic g
raining. In the second part of the paper the pore size distribution di
agrams are calculated from the adsorption isotherm for porous sulphuri
c acid films. It is shown that the dominant pore diameter corresponds
rather well to the pore diameter observed in transmission electron mic
roscopy sectional views. This means that the adsorption method can be
applied to study the porosity of the aluminum oxide films. The method
was then used to study the influence of the pretreatment on the porous
oxide film morphology.