Pulse plating of sacrificial Mn-Cu alloys from sulphate bath

Pulse plating of manganese-copper alloys from a sulphate solution with the addition of ammonium sulphate at pH 6-7 has been studied. The Mn-Cu electrodeposition system is characterised by steady state and transient electrokinetic methods. The influence of pulse current on cathodic efficiency, microstructure and morphology of the deposits was analysed and compared with the results achieved with continuous current. When short off-times are applied, a uniform and homogeneous morphology is obtained. All the deposits exhibit suitable mechanical properties and low copper content (<5 wt-%). The codeposition of copper prevents the phase transformation of as deposited ductile γ-Mn to the brittle and hard α-Mn for up to a few months.