Zinc and aluminum die castings to etching?

     Because zinc is an amphoteric metal, soluble in acid but soluble in both alkali. The zinc alloy die casting in zinc accounted for 90%. Investment castings (Aluminum content of 4% or so) so by zinc etching is reasonable to consider.

     As the zinc-Aluminum die castings dense surface layer is very thin (only 0.O5 ~ O.1mm) so the etching time to note. General erosion choose l%. 2% aqueous solution of hydrofluoric acid, or select 1% to 2% sulfuric acid aqueous solution at room temperature etching 5-30s can be transferred to the next step activation process.