Hot-dip galvanized coating for steel

• Main Author: MILLER; GEORGE T
• Format: Patent
• Language: English
• Published: 10.10.1989
• Subjects: APPARATUS THEREFOR; CHEMICAL SURFACE TREATMENT; CHEMISTRY; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; DIFFUSION TREATMENT OF METALLIC MATERIAL; ELECTROFORMING; ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; METALLURGY; PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTIONOF COATINGS; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION

A hot-dip galvanized coating for improved resistance welding of galvanized steel parts or sheets includes particles of a metal phosphide, and preferably ferrophosphorus particles, having a particle size of from about 0.1 to about 30 microns such particles being included in the galvanized coating while the zinc is still molten. The coating can also include up to about 40% by weight of the metal phosphide of an additional metal such as nickel, tin, aluminum or lead, which can be incorporated in the coating as discrete particles or deposited onto the surface of the metal phosphide particles. The advantages of the present invention include a significant reduction in welding current and an increase in electrode life, as well as simplified application of the coating by incorporating the metal phosphide particles directly into existing coating lines.