| 摘要 |
PURPOSE:To remarkably improve the secondary adhesion of a coated film and the corrosion resistance of the uncoated surface by forming a hydrated oxide film on a cold-rolled Al alloy, incorporating an Si compd. and a phosphoric compd. in the film, and tempering the alloy. CONSTITUTION:Cold-rolled Al or Al alloy is degreased, and then treated with a neutral or basic soln. to form a hydrated oxide film such as a boehmite film at 0.4-0.8g/m<2>. The cold-rolled material is treated with an aq. water glass soln. (contg. about 0.5-10% silicate), and about 0.01-0.05g/m<2>, expressed in terms of Si, silicon compd. is incorporated in the hydrated oxide film. The material is further treated with an aq. hydrophosphite soln. (about 1-20% concn.), and about 0.005-0.03g/m<2>, expressed in terms of phosphorus, phosphoric compd. is formed on the hydrated oxide film. The cold-rolled material thus treated is tempered at about 200-500 deg.C for several sec-about 20hr. By this method, the secondary adhesion of the coated film is improved, and the corrosion resistance of the uncoated surface after actual use is improved. |
