Hardening and smoothing effects of lignin sulfonates on the electrodeposition of lead

The codeposition of lignin derivatives from an acidic lead electrolyte was investigated with respect to the nature of the derivative, the additive concentration in the electrolyte and the current density. The lignosulfonates of sodium and calcium were incorporated in the deposits up to a volume fraction of 1.1-1.2% whereas the codeposition of alkali lignin was much lower. The lignosulfonates were dispersed in the deposit as small inclusions which were distributed very evenly. A significant hardening of the deposited lead, based on both grain refinement and dispersion strengthening by the included organic particles, occurred.