NiAl coating on carbon steel with an intermediate Ni gradient layer

Solar energy concentrated by a Fresnel lens can ignite a self-propagating high-temperature synthesis in a powder mixture of nickel–aluminium, for producing NiAl coatings on a carbon steel substrate. Processes are fast and economical, and there are no contaminants. A nickel powder layer was placed between the Ni–Al mixture and the steel for improving the coating adherence. The nickel powder layer gives rise to a Ni-rich layer, joined to the steel substrate, and a Ni3Al sublayer just under the NiAl coating. Samples were tested in two atmospheres: N2 and vacuum. Coatings produced in vacuum were completely deformed. Samples with different NiAl masses were tested in N2 atmosphere; a very large NiAl mass produced coatings with a volcanic shape.