The design, fabrication and preliminary assessment of novel metal reinforced ceramic matrix composite (CMC) materials are reported in this study. The design is based on the assumption that the metallic reinforcing structure can increase the work of fracture through the action of wire pullout, crack deflection and plastic deformation. In particular, the current CMC is composed of a molybdenum wire structure within a 7.5 wt% yttria-stabilized zirconia (7YSZ) ceramic matrix (Mo/YSZ). A unique jig is designed to assist the fabrication of the Mo mesh. Subsequently a NiCrAlY bond coat and finally a 7YSZ matrix are applied to the Mo mesh structure using a plasma spray technique. The as-fabricated and heat treated Mo/YSZ are subjected to impact and 3-point bend tests. The impact testing results show that heat treatment after spraying increases the impact energy possibly due to the improved bonding between Mo, NiCrAlY and 7YSZ. During 3-point bend testing, the incorporation of Mo mesh in 7YSZ increases the load at yield point, the peak load and the displacement to failure. After isothermal and cyclic oxidation tests at 1050°C for 330 hours, the Mo/YSZ CMC is examined under optical and scanning electron microscopes (SEM). The results show that the NiCrAlY bond coat delaminates from the Mo wire and also forms radial cracks during the spraying process. It is for this reason that the Mo wire suffers from rapid oxidization during isothermal and cyclic oxidation tests, causing separation of the reinforcement from the 7YSZ matrix. Future improvement to the current process will be to select and deposit a more effective oxidation resistant coating on the Mo wire in order to allow the metal frame-reinforced CMC concept to achieve the desired chemical and mechanical properties at high temperatures.
- International Gas Turbine Institute
Metal Frame Reinforced Ceramic Matrix Composite for High Temperature Applications
Kibsey, M, Mohammadi, T, Huang, X, & Kearsey, R. "Metal Frame Reinforced Ceramic Matrix Composite for High Temperature Applications." Proceedings of the ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. Volume 5: Manufacturing Materials and Metallurgy; Marine; Microturbines and Small Turbomachinery; Supercritical CO2 Power Cycles. Copenhagen, Denmark. June 11–15, 2012. pp. 81-89. ASME. https://doi.org/10.1115/GT2012-68293
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