| 摘要 |
<p>The substrate is covered with an aq. mixt. contg. 80 wt.% Cr acid, >0.0005 vol.% surfactant, 5-50 vol. % w.r.t. total liq. org. cpds. of C, O and H with a b.pt. >100 degrees C at atm. press., and with >=1 O-contg. parts of a hydroxyl, oxo or ether of low mol. wt., or a mixt. of these, and a metal such as Zn or Al or a mixt. of these in powder form. The mixt. is applied so as to give a deposit of is not > ca 53.8 mg/dm2Cr, and is not > ca 538 mg/dm2 metal in which the Cr to metal wt. ratio is not >0.5:1. The substrate is heated so as to evaporate the volatile constituents, and is then dipped into a electrolytic bath in which the coating acts as electrode. Method is suitable for precoating articles before welding.</p> |
