High-temperature conductivity of Mo-oxide cermet

Based on the general effective medium equation, the conductivity model of molybdenum-based cermet was established for the Mo-ZrO₂, Mo-SiO₂, and Mo-Al₂O₃ cermet, the influences of temperature, oxide, and relative density on the conductivity of cermet were investigated, and the experiment was used to verify. The results show that, the percolation thresholds of the oxides for the conductivity of Mo-ZrO₂, Mo-SiO₂, and Mo-Al₂O₃ cermet are 0.249, 0.095, and 0.145, respectively, and the critical exponents are 2.52, 3.20, and 2.90, respectively. The results calculated by the model are in good agreement with the experimental results. The conductivity of the cermet is presented the temperature-resistance characteristic of the electronic conductivity at lower volume fraction of the oxide phase, and the ionic conductivity at higher volume fraction of the oxide phase. The volume fraction of the oxide in the molybdenum-oxide cermet as high-temperature conductor materials should not exceed 0.6. The oxide type has little effect on the conductivity of cermet, and the relative density or porosity shows the significant effect on the conductivity of cermet. The relative conductivity decreases significantly with the decrease of relative density, and the relative density value is better more than 0.95.