Method for depositing an anti-corrosion coating

A process for depositing a corrosion-protection coating on a metallic substrate, the metallic substrate having at least one cavity having an equivalent diameter emm<2 mm and a length/width ratio of greater than 150, comprising the step of:

• depositing, on at least one portion of at least one of said at least one cavity, an aqueous suspension to form a substrate-suspension assembly, said aqueous suspension comprising powder of a metal to be deposited on said substrate, a protective agent for protecting surfaces of the metal powder, a diluent, an aqueous solvent, and at least one additive promoting wetting of said aqueous suspension on said substrate, wherein the particles of the suspension each have an equivalent diameter d such that d≤emm/10 and the additive is at least one organic compound selected from the group consisting of binder, dispersant, complexing agent, wetting agent, and plasticizer,
• prior to said deposition, combining said metal powder, diluent, aqueous solvent, and at least one additive;
• heating said substrate-suspension assembly to a temperature below 150° C. so as to eliminate said aqueous solvent;
• following elimination of said aqueous solvent, maintaining said substrate-suspension assembly to a temperature between 400° C. and 500° C. for 1 to 10 hours under an inert gas or a reducing gas or under vacuum so as to eliminate said at least one organic compound to produce a coated substrate;
• following said elimination of said at least one organic compound, performing a diffusion heat treatment of said metal toward said substrate by maintaining said coated substrate at a temperature between 500° C. and 700° C. for 1 to 10 hours under an inert gas or a reducing gas or under vacuum;
• following said diffusion heat treatment, eliminating any residues of diluent from said coated substrate;
• and
• following said elimination of residues, maintaining said coated substrate at a temperature between 900 and 1100° C. for 1 to 5 hours, thereby producing a substrate whose cavities are coated with a corrosion-protection coating.