Nickel-alumina composite coatings fabricated by cold gas dynamic spraying : A review

Coatings in industries are created for different applications such as thermal barriers, corrosion protection, wear protection, and biological applications, among others. For a wide range of functional properties, including mechanical, wear-resistance, electrical, chemical, electronic and magnetic, several surface engineering approaches are strategically developed. A broad range of materials, such as metals, ceramics, polymers, and composites, are coated on either related or unrelated materials. Different thermal spray coatings, such as plasma spray, HVOF, or laser cladding are commercially used. They require the feedstock material to be melted or partially melted, either in the powder form or wire form, followed by melting the molten droplets to create a lamellar structure coating. Because the temperatures involved are so high, the coatings used in thermal spray technology may show significant levels of oxidation, which limits their use in temperature-sensitive materials and other such industrial applications. In this context, cold gas dynamic spraying (CGDS) is a solid-state processing that is ideal for the deposition of substances that are oxygen-sensitive such as aluminium, copper, or titanium or for temperature sensitive materials such as nanostructured and amorphous powders. However, for industrial applications, where corrosion and wear resistance are necessary, i.e. power generation industries these coatings fail. Hence, addition of ceramic particles is imperative. In this regard, nickel-alumina coatings on mild steel are used for marine, atmospheric and high-temperature applications. Nickel-alumina composite coatings have been deposited using thermal spraying, HVOF, plasma spraying, but there is not adequate research using cold spray. Therefore the main aim of this research paper is to explore and classify the applications of Ni-Al2O3 composite coatings using cold spraying technology.