INVESTIGATION OF PRODUCTION PARAMETER EFFECTS ON SPARK PLASMA SINTERED MOLYBDENUM CERMET WAFERS FOR NUCLEAR THERMAL PROPULSION APPLICATIONS
This study focused on nuclear fuel fabrication using powder blending and spark plasma sintering (SPS) of Mo-ZrO2 surrogate ceramic-metal (cermet) fuels. The study consisted of two co-projects: a powder blending/distribution study and an SPS parameter optimization study. The powder blending study focused on optimization of the powder processing parameters in order to fabricate high density cermets with uniformly distributed dispersed ceramic microstructures. The SPS parameter optimization study focused on the impact of sintering parameters (temperature, dwell time, and pressure) on the microstructural properties of a cermet (density/porosity, grain structure, and hardness). In the powder blending and distribution study, addition of 0.1 wt% and 0.5 wt% binder resulted in complete coverage and even distribution of large, spherical ZrO2 particles with Mo powder for batches of 50 vol% and 60 vol% ceramic loading respectively. When optimizing SPS parameters, fuel density (decreased porosity) was directly related to increase in sintering temperature, pressure, and time. Grain diameter and material hardness were observed to increase with temperature and pressure as well, indicating grain growth during the sintering process. Optimal sintering parameters suggested from this study, for Mo-ZrO2 cermets with 60 vol% ceramic loading, were found to be at a temperature of 1400C, at 50 MPa uniaxial pressure, for at least 5 minutes dwell time.
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