IMPROVEMENT TO CYANIDE-FREE, ALKALINE COPPER STRIKE BATH, FOR ACHIEVING IMPROVED, SATISFACTORY ADHESION TO ZAMAK ALLOYS AND INCREASING BRIGHTNESS

摘要

The invention modifies commercial strike baths by adding a series of organic and inorganic compounds aimed at making the strike bath suitable for processes carried out in a rotary drum. The suitable ranges for the operational variables (temperature, stirring, pH and current density) and chemical composition (1-hydroxyethane, diphosphonic acid HEDP, Cu2 ion and additive concentration) are set in order to provide a strike bath having a satisfactory performance, thanks to the increase in HEDP concentration and pH, and to the admixture of potassium chloride. The deposits produced by adding salicyl sulphonic acid to the HEDP-based strike bath exhibit, besides a satisfactory adhesion, increased brightness in comparison with deposits produced from cyanide-containing baths without additives such as levelling and brightening agents.