CORROSION PREVENTIVE STEEL PLATE HAVING EXCELLENT CORROSION RESISTANCE AND HOT WATER SECONDARY ADHESION

摘要

PURPOSE: To provide the corrosion preventive steel plate which is excellent in corrosion resistance and hot water secondary adhesion by constituting a ZnCr alloy formed by an electrodeposition method on the steel plate of phases of hexagonal crystals and cubic crystals which are respectively specific in lattice constants. ;CONSTITUTION: The steel plate is subjected to Zn-Cr alloy plating consisting of the phase which is hexagonal in the crystal system and has a structure of lattice constants of a=2.72 to 2.78Å, c=4.43 to 4.60Å and the phase which is cubic in the crystalline system and has a structure of lattice constant of a=3.00 to 3.06A. As a result, the desired corrosion preventive steel plate is obtd. While the production conditions for obtaining the Zn-Cr alloy plating are not always limited, zinc sulfate and chromium sulfate as chief materials, sodium sulfate as a conduction assistant, formic acid and various kinds of org. acids as pH buffers, and others, such as various kinds of surfactants may be added to the bath in the case of electrodeposition from, for example, the sulfuric acid bath. The desirable phase constitution is obtd. by properly selecting others, such as bath pH, bath temp., liquid speed and electrolytic current density.;COPYRIGHT: (C)1994,JPO&Japio