GE researchers are working with an additive manufacturing process called “cold spray,” in which metal powders are sprayed at high velocities to build a part or add material to repair an existing part. Cold spray is part of GE’s expanded additive manufacturing toolkit.
Spray technologies are particularly attractive for the production of large structures, which are challenging for today’s powder-bed additive manufacturing processes due to equipment size limitations. The cold spray technique has the potential to scale up to build larger parts, with the only limitation being the size of the area over which metal powders can be applied.
In a paper published earlier this year in the International Journal of Advanced Manufacturing Technology, French and Russian researchers discussed the application of cold spray (CS) coating deposition technology as an additive manufacturing technique and explained noted that:
Previous studies demonstrated that cold gas dynamic spray coating deposition technology or simply cold spray (CS) could be adapted for performing of 3D object fabrication. In this process, the particles of deposited materia are accelerated to high velocities by supersonic gas flow delivered by supersonic nozzle. If the particles velocity exceeds certain critical value, the energy of the particle-substrate impact leads to intensive plastic deformation of particle and, in some cases, surface of substrate.
This process breaks thin films on substrate and particles surface formed from oxides and establish intimate contact between “clean” chemically active materials of substrate and particle that leads to the creation of strong bonding.
The advantage of this technique is that the amount of heat transferred to the powder or to the substrate is relatively small. Therefore, retention of the microstructure as well as the mechanical and chemical properties of the feedstock powder is facilitated.—Sova et al.
Cold spray—also known as 3D painting—demonstrates a unique marriage of materials, process, and product function which can, in the immediate future, transform repair processes for industrial and aircraft components such as rotors, blades, shafts, propellers, and gear boxes. Since cold spray does not require heat, as do common repair processes such as welding, it allows a repaired part to be restored close to its original condition.
In GE’s Oil and Gas business, GE researchers are exploring cold spray as an alternate way to repair or coat parts involved in oil and gas drilling and turbo machinery.
In addition to being able to build new parts without welding or machining, what’s particularly exciting about cold spray as an innovative, 3D process is that it affords us the opportunity to restore parts using materials that blend in and mirror the properties of the original part itself. This extends the lifespan of parts by years, or possibly by decades, ultimately providing improved customer value.—Anteneh Kebbede, Manager of the Coating and Surface Technologies Lab at the GE Research Center
A. Sova, S. Grigoriev, A. Okunkova, I. Smurov (2013) “Potential of cold gas dynamic spray as additive manufacturing technology,” International Journal of Advanced Manufacturing Technology doi: 10.1007/s00170-013-5166-8