Question

Pure Mn can be electroplated quite well onto steel, and it forms an adherent coating on the steel. The standard electrode potential of Mn is more electropositive than Zn, and hence the Mn can perform the function of sacrificial anode more effectively than Zn in terms of electrode potential. In addition, electrolytic Mn prices are usually lower than the price of Zn. However, Zn coating on steel is widely used while Mn-coated steel has no market. Describe two possible reasons why Zn is preferred to Mn for this use

Answer 1

use of Zn is preferred over Mn because of following two reasons -

• pure manganese galvanic coatings have high chemical activity
• pure manganese is highly brittle in nature

This may happen because of change of crystalline modification of pure manganese.

so now these days, Chemical activity and brittle form of α-Mn can be reduced by alloying it with metals such as copper, zinc, cobalt, nickel, iron and others having a lower negative standard potential.

The plastic γ-Mn tetragonal face-centered structure is obtained by electrodeposition. After a short time, γ-Mn transforms into stable, brittle, body-centered cubic α-Mn [2].

I hope this information will help you

Thank you!!