| 摘要 |
PURPOSE:To increase peeling strength of a coated Zn layer and to enhance corrosion resistance and also to enable free processing such as blending work after Zn treatment by mechanically subjecting an extruded Al stock to roughened surface processing at the specified surface roughness just after extruding the Al stock and thereafter treating it in a melted ZnF2 bath and then baking it. CONSTITUTION:An extruded stock 5 obtained by extruding a billet 1 of Al (alloy) is worked at 6-30mu surface roughness just after extrusion with a roughener 7 which mechanically performs roughened surface processing such as shot blasting. Then after immersing a short-sized extruded stock 5' which is obtained by cutting it at proper length into a melted ZnF2 bath 9, a Zn diffusion layer is formed by drawing up it from the bath 9 and successively baking it. Further the extruded stock 5 is desirably a flat tube having many holes. By this method, even when performing bending work or the like, free processing can be performed after Zn treatment because pitting corrosion is not caused. |
