Electrodeposits with improved corrosion/blistering props - - for ferrous substrates in outdoor use

摘要

Substrate is initially coated with brass, pref. 52-59 wt. % Cu, balance Zn, of thickness 0.0001-0.0010 ins, or for enhanced blister resistance only 52-70 wt % Cu, balance Zn, of thickness 0.0001-0.0004 ins. Surface layer, usually Cr, is applied to brass. A layer of Ni can be inserted under the Cr and a copper strike can be carried out before deposition of the brass - but these are unnecessary in most cases. Coatings are applied by standard electroplating procedures; the brass from a cyanide bath, agitated with air and under current density of 30-40 A/ft2. Protective system is very suited to automobile components.