B&B precision: alumina coatings

High temperature environments represent a challenge for any metallic component and many components used in the refractory, glass or metal processing industries may only have a limited shelf life. B&B Precision provide thermally sprayed Alumina coatings and here is more information on the material, its application and the advantages of the process.

What is Alumina?

Alumina is a chemical compound consisting of Aluminium and Oxygen, it is classed as a Ceramic material due to its high melting point and electrical resistance. Although Aluminium Oxide is most commonly referred to as Alumina it may also be referred to as Aloxide, Aloxite and Alundum all of which are particular forms of the same material. It is white in colour and can be powder coated.

Thermal Spray Advantage

Ceramic materials by their very nature are brittle, limiting their application but the advantage with a coating is that you can take a metallic component and insulate it with alumina, enhancing its properties. The thermal spray process takes Aluminium Oxide powder, heats it up and fires it out at extreme velocities forming a low porosity coating that is very hard and dense in nature. The advantage of this process is it is additive in nature and as you build up the amount of ceramic, the amount of material you in turn enable a component to withstand a higher voltage. You can also apply thermal spray coatings more selectively to a surface making it ideal for electrical barrier components.

Alumina Applications

The thermal spray process produces coatings that are naturally hard and dense in nature and a typical hardness of around 60HRC, due to the high velocities involved in the process, in many cases the coating will impregnate the base metal and should never flake off. Alumina coatings remain stable at high temperatures and should be able to withstand 1450c, and this is the reason that Alumina coatings are popular in the refractory sector. They are able to withstand molten materials and will certainly extend the part life of any chutes/funnels that are in regular contact with this material. Alumina is claimed to be chemically inert but in our own testing we have seen some degradation when in contact with hydrochloric acids but certainly it provides a high level of corrosion. Aluminium Oxide coatings can be used for anything from furnace linings, to electrostatic chucks to biomedical implants.

B&B Precision are sub-contract manufacturers who offer CNC machining and HVOF applied coatings. We can provide a wide range of hard wearing coating options including Tungsten Carbide, Stellite 6, Inconel and of course Alumina. We are based in Yorkshire but deliver across the country.


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