| 摘要 |
A method for producing a multi-layer anodic coating comprises the steps of placing a metal in a first electrolytic solution and applying a current to form a first anodic layer having a barrier region, reducing the applied current to cause a reduction in thickness of the barrier region and placing the metal in a second electrolytic solution and applying a current to form a second anodic layer. The method may further comprise the step of sealing an interface between the first and second anodic layers. The first and second layers may be phosphoric acid and sulphuric acid layers respectively. A coating or adhesive, preferably a sol-gel, may be applied to the phosphoric acid layer. An aluminium component comprises the multi-layer anodic coating of the invention. Also disclosed is a multi-layer anodic coating comprising duplex anodic structure comprising phosphoric acid and sulphuric acid anodic layers comprising pores having a diameter in the range 50 to 100 nm and 10 to 25 nm respectively. |
