Patent ID: 8192801
Filing Date: 2012-06-05
Classification: B05D,C09D,C23C,C25D

Abstract:
1. A method for protecting an article against corrosion, the article comprising a magnesium surface portion and at least one of a steel surface portion and aluminum surface portion, the method comprising: providing a first aqueous e-coating emulsion in which water can react with the magnesium surface to generate hydroxyl ions at the interface of the magnesium surface and the e-coating emulsion, the emulsion having dispersed therein a cathodic electrocoat composition that destabilizes in a basic aqueous environment; and exposing at least the magnesium surface of the article to the first aqueous e-coating emulsion without applying a current or potential to the article to deposit an e-coating pre-film exclusively on the magnesium surface, and wherein the e-coating pre-film provides the magnesium surface with temporary protection against a chemical reaction with water in a neutral or acidic aqueous medium; exposing at least the steel and/or aluminum surfaces of the article to a conversion coating solution to deposit a conversion coating on the steel and/or aluminum surface portions; and exposing at least the steel and/or aluminum surface portions to a second aqueous e-coating emulsion and applying a current or potential to the article such that it serves as a cathode, and wherein the application of a current or potential deposits an e-coating pre-film on the aluminum and/or steel surface portions.