A study was made on the hydrophobic modification of γ-alumina and boehmite powders with isopropyl triisostearyl titanate (TTS). The TTS treatment was performed by dipping 10g of each powder in 200ml of TTS benzene solution for described time. The powders showed hydrophobic properties and thus floated on water, as a result of treating them with TTS solutions of over 1×10^-2mol/l concentration for γ-alumina and of over 1×10^-3mol/l concentration for boehmite. Dipping was enough for 15 minutes. In hydrophobing of the powders, the de-alkoxylation reaction between TTS and the surface hydroxyl groups of the powders takes place as -OH→-O-Ti-(OCO(CH₂₎₁₄ CH (CH₃₎₂₎₃. It was presumed that the number of reacted surface hydroxyl groups was about 4% of the number of surface hydroxyl groups.

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Anodized alumina coating formed in phosphoric acid bath at the voltage lower than that employed in the usual method has been multi-colored. The colors cover primary color, together with brown color, by varying the a. c. electrolytic duration in nickel sulfate bath. They are controlled by varing the thickness of the coating and the size of deposits in the pore. The multi-coloring of the coating is considered to be caused as follow: In the case when the thickness of the coating is thinner than about 1μm, the color of the coating seems to be based mainly on the interference color which is due to the distance between surface of the coating and top of the deposits in the filled pores. When the thickness of the coating is thicker than about 1μm, the color of the coating seems to be depending on the color of the deposit, complementary color against the color of the deposit, and the interference color which is based on the size of the deposits.

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