Cold spray is a solid-state line-of-sight additive manufacturing process which enables the deposition of powdered feedstock materials via kinetic impact energy. Sprayed through a supersonic nozzle with compressible gases (e.g., nitrogen and helium) particles are accelerated to impact velocities of 150 m/s to 1,500 m/s where particles adhere to the surface through a combination of high strain rate plastic deformation, adiabatic shear induced bonding, and mechanical interlocking. Owing to its low-temperature nature, high material throughput capabilities, and ability to produce composite architecture, cold spray has gained traction in repairing high value, temperature sensitive components, large format additive manufacturing, and manufacturing of advanced materials. Recently, cold spray has been demonstrated to also produce coatings from highly brittle materials for applications in energy, aerospace, and defense sectors through feedstock and particle impact velocity control. However, the development of processing windows for brittle materials poses significant challenges. In this presentation, we present the potential of cold spray in producing W, W-Ta, YSZ, and Al2O3 coating systems for high temperature coating systems and repair of existing assets achievable through computationally guided control of powder particle size distribution selection and particle impact velocity control. The preliminary results show that dense deposits of W, W-Ta composite, YSZ, and Al2O3 coatings can be produced. While thick deposits of W-Ta composites with up to 50% W concentration can be achieved, growing the thickness of pure W coatings beyond 70 µm requires further research. In the deposition of YSZ and Al2O3, meso-scale conformal coatings as thick 10 µm are achievable. These results are promising for further development for the use of cold spray in fabricating thermal diffusion systems and high temperature environmental barrier coatings.
