Inhibition of the aluminum+water reaction

Abstract

The aluminum+water reaction proceeds by dissolution of the outer surface of the amorphous oxide and precipitation of a porous hydroxide. The reaction is accelerated by the hydroxide layer, as long as it provides sites for deposition of soluble close to the surface. Inhibitors prevent hydroxide formation and eliminate such deposition sites so that soluble species must diffuse into the bulk of the solution, a much slower process. Strong inhibitors include phosphate, silicate, arsenate, periodate, and tungstate. Inhibitor strength correlates well with the acidity and structure of the ion.