In Cold Spray technology the propellant gas is heated typically up to 1000°C, as the deformation of the particles being sprayed and their adhesion to the target is thermally activated. In simple terms, hot and soft powders lead to denser, stronger coatings. However, if metal powders are soft to begin with the process is enhanced.

• Harder particles have a greater tendency to bounce off the target and not be included in the layer.
• This leads to waste and means it takes longer to achieve the desired thickness.

Challenge

In this case study PSI’s client needed to repair battle-damaged military aircraft. Surface to air or air to air firing exchanges may have led to cracks or holes in the air frame structure. In the heat of conflict there is no time to take the aircraft back to the factory for repair, it must be put back into service within hours.

• Develop the rapid solidification technology with a specialty quench function.
• Material development to produce soft aluminium powders for Cold Spray application.

Overcoming the Problems

Repair by welding is not satisfactory because the heat of MIG or TIG welding weakens the metal next to the weld, making the repair unsatisfactory.

Knowing this, the client has selected cold spray as the repair technique of choice. The problem was that the aluminium powders used for cold spray repair were hard because they were made by gas atomisation.

What was needed was a new aluminium alloy that could be heat treated (solution heat treatment) in a Fluidised Bed Reactors (FBR) that it would be supplied to the battlefield in a soft condition so it would arrive in a condition suitable for Cold Spray application.

Final Result

PSI constructed and proved a FBR which could apply this special heat treatment.

Our FBR range are suitable to heat treat a large range of metal powders. They are able to apply very precise applications of heat treatment regimes and, crucially, incorporate a rapid quench facility to maintain a solution heat treated microstructure.

Visit the Fluidised Bed Reactor page for more information or contact us to discuss the technology.