Influence of crystallographic orientation on the corrosion rate of aluminum in acids and alkalies

Th e co rros ion of singl e crystals of high-puri ty aluminum i n strollg ac id and alkali media is di sclosed as an ordedy process, the rate of attack bein g de pendent on the ori ent ation of the corroding s L Ilface. For a 15-percen t N aOH solution , corrosion a pparent ly prog ressedby r evealin g facet surf3ces of the [335] ty pe, resul t in g in g ross co rrosio n of s ph eres int o cubes; In contrast, s ubstan t iating other invest igatio ns, corros ion in aqua regia-hydroflu o ri c aci d mi xt ure r eveal ed etch pits wi t h surfaces of t he [1 00] ty p e, resul t in g in gross co rros ion of s ph eres into equilateral octa hedra. Observat iolls of the co rros ion bv acid and a lka li solu t ions of dis ks \ h ce nt ral ho les, and r ectangu la r pris ms, both of mon oc rvstallin e a luminum , r es ul t in in teresting co nc lu sio ns and co mpariso ns wi t h res pect to th e cOITos ion process.