| 摘要 |
A chemical etchant for etching Ti-W alloys in the presence of a protected metal not to be etched comprises the following mixture: (a) 1-2 parts by vol. of 30 wt.% aq. H2O2; (b) 1-2 parts by vol of water in which EDTA is dissolved at 15-40 g/litre; and (c) 100-200 g of a salt per litre of mixture, wherein the salt dissociates in the mixture to passivate the protective metal with a protective coating. Also claimed is a method as above for selectively dissolving Ti-W, wherein the protected metal is from the gp. comprising Al, Al-Cu, Cr-Cu, Cu, Pb, Sn and Pb-Sn. Also claimed is a chemical etchant as above, wherein the mixture is maintained at 40-60[deg]C as an effective etching temp.. The salt added to the mixture is a metallic sulphate, most pref. K2SO4. The etchant is adjusted to have a pH less than 7.0. |
