Method of applying a magnesium-containing powder to the surface of an aluminum or aluminum alloy substrate

摘要

Disclosed are methods of treating a metal to improve the metal's corrosion resistance. The method includes applying, to the surface of the metal, a coating which comprises magnesium powder and a binder. The present invention also relates to a coating composition that includes magnesium powder and a silane modified epoxy isocyanate hybrid polymer or prepolymer. The inventors have found that corrosion resistance (as determined by Prohesion™ exposure in accordance with ASTM D5894-96, which is hereby incorporated by reference) in excess of 3,000 hours on 2024 T-3 aluminum alloy can be achieved with the methods and coating compositions of the present invention.

主权项

1. A coating composition comprising: magnesium powder; and a silane modified epoxy isocyanate hybrid polymer or prepolymer,
wherein (a) said magnesium powder comprises a mixture of a first magnesium particle powder and a second magnesium particle powder, wherein the first magnesium particle powder and a second magnesium particle powder have substantially different mean particle size distributions, wherein the mixture's bulk density is greater than that of the first magnesium particle powder's bulk density, wherein the mixture's bulk density is greater than that of the second magnesium particle powder's bulk density, and wherein the first magnesium particle powder has a mean particle size distribution of from about 25 μm to about 35 μm and wherein the second magnesium particle powder has a mean particle size distribution of from about 65 μm to about 75 μm; or wherein (b) said silane modified epoxy isocyanate hybrid polymer or prepolymer comprises a polyisocyanate prepolymer, an epoxy prepolymer, and a silanated tetrahydroquinoxalinol crosslinker or a polymerization product thereof.