Spray forming technology is rapidly becoming one of the most cost-effective and reliable ways of producing aircraft engine parts from nickel and aluminium superalloys. The technology uses tiny atomised droplets of metallic alloys to produce components that in many cases are stronger and tougher than traditionally produced parts. The process allows the construction of large components which could ultimately result in larger engines and larger aircraft.
Metals are atomised during the process using Argon or Nitrogen gas to form droplets (10-500 micrometers) that are then deposited onto the surface of the pre-formed component via a spray cone. Adding ceramic particulate (5-15 micrometer Silicon Carbide) converts the alloy coating to form a metal matrix composite. The process is particularly advantageous in manufacturing certain components such as engine rings and engine casings where the process can, in some instances, reduce production costs by up to 30% compared to traditional methods.
As aeroplane engines get larger, it becomes increasingly difficult to produce components that satisfy stringent safety criteria through traditional means. Spray forming technology produces components that match, if not exceed, the strength and fatigue properties of traditionally produced parts and in many cases, alloys previously unsuitable for use in aerospace parts can be fully utilised.
Patrick Grant from the Defence, Evaluation and Research Agency (DERA) says, "Spray forming has moved from the laboratory to the production environment for some nickel and aluminium based alloys. This trend is likely to continue, but benefit will best be realised where cost reduction is combined with the development of alloys designed to exploit the unusual solidifications of spray forming."