Additively Manufactured High Temperature Centrifugal Impellers for Low Cost SOFC Recycle Blower

Innovative manufacturing processes are needed to reduce the costs of Solid Oxide Fuel Cell SOFC balance of plant BOP equipment. Mohawk Innovative Technology, Inc. MITI and its subcontractor Velo3D are working to implement 3D printing or additive manufacturing to reduce the cost of impellers, volutes, and other components for high temperature anode gas recycle blowers ARCBs, as these are significant contributors to the BOP cost of SOFC installations. This effort is a continuation of ongoing work at MITI for development of novel, low cost, oilfree ARCB systems that operate maintenancefree in the challenging high temperature and corrosive environments posed by SOFC anode exhaust gases. The centrifugal impeller of the SOFC ARCB operates in extremely challenging mechanical stress and high temperature conditions, and therefore is one of the highest cost parts of the system. This is partly due to the need for use of high strength and difficulttomachine nickel base superalloys such as Inconel 718 or Rene 41 for their fabrication which can withstand such conditions, but also due to their geometric complexity, which requires expensive computer numerical control CNC manufacturing. It is expected that the cost of impeller manufacturing would be reduced if conducted by state of the art additive manufacturing methods, since these are becoming increasingly insensitive to part complexity, and the time required to produce 3Dprinted parts is much shorter than by CNC. Currently, most parts fabricated by additive manufacturing are used for static, nonrotating components, with relatively few instances of experimental applications in small high speed/temperature turbomachinery. Therefore, the goals of this effort are to reduce manufacturing costs, characterize mechanical properties of 3Dprinting materials, demonstrate complex rotating part manufacturability, and increase confidence that these methods can produce safe/reliable rotating components. Successful demonstration of these methods with impellers would pave the way for their use not only in fabrication of other ARCBs parts like shafts and housings, but also in 3D printing other SOFC BOP components, and eventually, in turbomachinery for more general applications such as gas turbine engines and supercritical CO2 turbomachinery. During Phase I of the project, MITI and subcontracting partner VELO3D characterized key mechanical properties of 3Dprinted Inconel 718 tensile strength and modulus of elasticity, fabricated multiple impeller designs by additive manufacturing, and performed laboratorybased analysis and static component testing of the 3Dprinted impellers.