Effect of surface preparation on zinc electrodeposited texture

Abstract

The texture and morphology of zinc coatings deposited onto a low carbon steel substrate that was electropolished or mechanically polished have been compared. The morphology and texture of zinc coatings on electropolished and mechanically polished surfaces were quite different. Zinc crystallites laid on each other in a specific variant on each grain of electropolished surfaces, but stacked zinc crystallites were seen in variants all over the substrate on mechanically polished substrates. Zinc electrodeposited on an electropolished surface exhibited {11.5} and {11.6} nonfiber texture components plus {00.2} basal fiber. It was shown that the nonfiber texture component resulted from epitaxial growth via 2D nucleation following bunching growth, while {00.2} basal fiber is promoted during nonepitaxial growth, which proceeds trough 3D nucleation and oriented growth. On mechanically polished surfaces, because of some surface inflictions, epitaxial growth did not occur. Slower surface diffusion of zinc adions on mechanically polished surfaces with respect to the electropolished surfaces is also responsible to prevent {00.2} basal fiber texture formation, which is expected to develop during the coating growth at low overvoltages. Therefore, only the lower intensity of {11. X} components, which tend to be fibers, was detected on mechanically polished substrates.