用正电子湮没寿命谱法研究铝阳极氧化膜

STUDY OF ANODIC FILM ON ALUMINIUM BY USING POSITRON ANNIHILATION LIFETIME SPECTROSCOPY

退火纯铝(99.99%)在15%H_2SO_4中于不同电解条件下进行阳极氧化,然后测其正电子湮没寿命谱,寿命谱拟合为三个寿命成份,指认第二寿命成分为e^+在氧化膜中的湮没。从I_2随电解条件的变化推知膜厚与槽压近似成正比,在恒温和固定槽压条件下,膜厚只能达到某极限值。根据τ_2的变化推断出,使用较高槽压或延长电解时间均使膜的结晶度提高,它诱发了裂缝或微洞的形成,导致膜体松散。根据上述结论进一步分析提高膜机械性能的可能途径。

The anodic oxidation of annealed pure aluminium (99.99%) was carried out in 15% H_2SO_4 at different electrolytic conditions. The positron annihilation lifetime spectra of the anodized aluminium were measured and fitted into three lifetime components. The second component(τ_2,Ι_2) was assigned to the positron annihilation in the anodic film. It has been deduced that, from the Ι_2 curves, the film thirkness is propertional to the cell voltage and reaches a limit under constant cell voltage and temperature and that, from the τ_2 curves, the crystallinity of the anodic film increases with increasing cell voltage and anodizing time. The local crystallization in the anodic film would induce the void-like defects and hence resuh in the film less compact.An idea for improvement of mechanic properties of the anodic film on aluminium has been proposed.