Abstract
Electropolishing of cast iron is seldom applied, for its throwing power is very poor due to the intricate structures such as ferrite, cementite and graphite. Especially, electropolishing effects depend on the distribution of graphite on the surface of cast iron. The author, however, investigated the electropolishing of cast iron in phosphoric acid-chromic acid bath and caustic soda-sodium dichromate bath.
The results are as follws:
1) The same smooth surface as in the case of carbon steel is obtained if acid or alkaline bath is used according to the quantity of graphite contained in the cast iron.
2) Malleable cast iron can well be electropolished in both acid and alkalline bath with oxydizing agent such as chromic acid or sodium dichromate.
3) Cast iron as cast has not much graphite but its crystalline structure is coarse, so that the bright surface by electropolishing cannot be obtained, which would be much improved by heat treatment of the cast iron.
