Corrosion-resistant sprayed coating, method for forming same and spraying device for forming same

A device for forming a corrosion-resistant sprayed coating,

• which is a flame-type thermal spraying device for forming a corrosion-resistant alloy coating comprising aluminum on a substrate surface,
• comprising a thermal spray gun having a function wherein a flame including melted material particles is jetted toward a substrate, and the flame is partitioned from the open air in an upstream region on said jet path, and a function wherein, in a downstream region, the material particles and the flame are forcibly cooled by a jet-gas or jet-mist before reaching the substrate,
• wherein the thermal spray gun has an inner cylinder and an outer cylinder, forming a conical gap there between, at the outer periphery thereof, and the jet-gas or jet-mist is supplied from an annular jet opening at the forward end of the gap, so as to produce a cylindrical flow, concentric with the jetted flame, gradually narrowing at an angle such as to intersect the centerline at a distance from the flame jet opening that is 3 to 7 times the diameter of the flame,
• and thereby a corrosion-resistant alloy sprayed coating comprising aluminum, which has a porosity of 1% or less with the surface thereof unsealed, and forms a microstructure with a grain size of 10 μm or less, is formed on the substrate surface.