The role of textures in the corrosion resistance of electrogalvanized Zn coatings

摘要

The generation of zinc coatings on steel sheet is one of the commercially most important processing techniques used to protect steel components exposed to corrosive environments. The coating properties are closely related to the microstructure of electrodeposits. One of the important factors that influence on the coating properties is texture. The texture of zinc coatings showed significant variations with the changes of the textures of steel sheets which were used as the substrates of zinc coatings. This study demonstrates a relationship between the corrosion behavior of the electrogalvanized zinc coatings and their textures as the texture changes of the substrates and the current density changes during electrodeposition. The texture of the zinc coatings on α fiber textured steel sheets was characterized by a {10·3} non fiber texture as a major component and a {00·2} fiber texture as a minor component. On the contrary, the texture of the zinc coatings on 7 fiber textured steel sheets was characterized by a mixture of the {00·2} fiber texture and the {10·3} fiber texture when deposited at low current density. The texture of the coating was gradually changed into a {10·3} pyramidal texture as a major component and a {00·2} fiber texture as a minor component as deposition current density increases. The coatings with a {00·2} texture have better corrosion resistance than those with a mixed texture of {10·3} and {00·2} components.