Patent ID: 11912879
Assignee: TOYOTA JIDOSHA KABUSHIKI KAISHA
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC C  F  H  Y | IPC C  F  H

Claim 0:
1. A film forming method of a corrosion resistant film, comprising:
bringing a substrate made of aluminum into contact with an aqueous solution containing sulfate ions and fluoride ions; and
heating the substrate to boil the aqueous solution on a surface of the substrate to form a corrosion resistant film on the surface of the substrate, the corrosion resistant film containing oxygen, fluorine, and sulfur derived from the aqueous solution and aluminum derived from the substrate,
wherein during the heating, air bubbles are repeatedly generated in the aqueous solution on the surface of the substrate and desorbed from the surface of the substrate, resulting in repeated dissolution of an oxide film on the surface of the substrate and repeated taking of the sulfate ions and the fluoride ions into the surface of the substrate to form the corrosion resistant film.