Stability of chromium dioxide particles in aqueous media

Abstract

An investigation was carried out to characterize the dissolution behavior of stabilized and unstabilized CrO2 particles in water, used in magnetic recording. Special attention was paid to the measurement of Cr(VI) concentration in the contact solution and to the elucidation of the effects of the stabilizing treatment by x-ray photoelectron spectroscopy (XPS). The experimental results indicate that both stabilized and unstabilized CrO2 particles predominantly release hexavalent chromium when in contact with water. The solubility of freshly stabilized CrO2 is considerably smaller than that ofunstabilized CrO2, but the difference in solubility diminishes with aged particles. The XPS study indicated that stabilization of 002 particles with a bisulfite solution results in the formation of Cr203 or a Cr203-like product on the particle. However, it appears that Cr(III) oxide coating does not uniformly form on all particles.