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Cold Spray Additive Manufacture of Combustion Chambers

Partner: Impact Innovations GmbH

A collaboration between AEL and Impact Innovations GmbH studied the production of bimetallic combustion chambers using Cold Spray Additive Manufacture (CSAM). Impact Innovations GmbH are a leading cold-spray equipment manufacturer, based in Germany, and experts in the CSAM process. Representative demonstrator samples were designed by AEL suitable for CSAM manufacture and were manufactured in CuCrZr/IN625 by Impact Innovations in their R&D spray lab.

Cold Spray Additive Manufacture (CSAM) involves seeding metal powder into a stream of inert gas that is heated at pressure and then accelerated to supersonic speeds through a nozzle. The powder is sprayed at a target using a robot where it deforms and solid-state welds to form deposited material which is then post-machined. CSAM has several key advantages over powder-bed fusion (PBF) methods for the manufacture of combustion chambers for liquid rocket engines:

  • No build volume limit and no fixed tooling
  • Multi-material or graded materials (including dissolvable fillers)
  • Fast deposition with low powder loss.
  • Powder is only required for the material to be deposited, in contrast to PBF methods where the entire build volume must be filled.
  • Machining quality geometry and surface finish
  • Access for inspection between layering processes.
  • Ability to join other parts without welding (e.g. injector head or actuator mounts)
  • Excellent material properties
  • Negligible thermal stress

CSAM has the disadvantage of requiring several steps of machining, however, as per traditional electroforming manufacturing routes.

This video by Impact Innovations GmbH shows the manufacturing process for a demonstrator nozzle exit with integral manifold, taken in their R&D spray lab. The copper and nickel alloy layers are built up one-by-one, with a turning process between each spray step. A machined aluminium mandrel is used on the nozzle internal diameter and another to fill the manifold area. Samples were also produced for sections with high aspect ratio coolant channels.