| 摘要 |
A process for making an improved composite aluminum article having an intermediate layer of porous coarsely crystalline aluminum oxide integral with the aluminum substrate. The oxide is electrolytically formed by applying a voltage which is steadily and continuously increased from start to finish of the electrolysis from about 5-15 volts to about 65-85 volts at a rate of about 1-3 volts/minute and utilizing a current density which is increased from start to finish of the electrolysis from about 10-30 amps/sq. ft. to about 60-80 amps/sq. ft. at a rate of about 1-3 amps/sq. ft./minute. A preferred electrolyte bath comprises about 15-20 oz./gal. 66 DEG Baumé sulfuric acid, about 2-3 oz./gal. malonic acid, about 2-4 oz./gal. oxalic acid, about 0.5-1 lbs./gal. carbon powder, and about 2-4 oz./gal. sucrose. The crystal lattice of the aluminum oxide layer is saturated with a salt of a divalent or trivalent metal which forms a complex with the aluminum oxide of enhanced strength, hardness and corrosion resistance, and may include the application of a low friction material for enhancing the appearance and function of the treated aluminum article.
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