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摘要: 以Mo-ZrO2、Mo-SiO2和Mo-Al2O3金属陶瓷为研究对象，基于通用有效介质方程建立金属陶瓷的电导率模型，分析温度、氧化物类型、相对密度等因素对其电导率的影响，并利用实验进行验证。结果表明，三种金属陶瓷电导率的氧化物临界体积分数分别为0.249，0.095和0.145，临界指数分别为2.52，3.20和2.90。电导率模型计算结果与实验结果吻合程度较好。当陶瓷相体积分数较低时，呈现电子电导的温阻特性；当陶瓷相体积分数较高时，呈现离子电导的温阻特性。金属钼-氧化物金属陶瓷高温导体材料中氧化物体积分数不宜超过0.6。氧化物类型对金属陶瓷的导电性能影响较小，相对密度或孔隙度对金属陶瓷电导率影响较大，相对电导率随着相对密度的降低而急剧减小，相对密度值以大于0.95为宜。Abstract: 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.
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Key words:
- molybdenum-based cermet /
- conductivity /
- numerical simulation /
- oxide /
- relative density
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图 4 钼基氧化物金属陶瓷电导率随温度变化
Figure 4. Electrical conductivity of the Mo-based oxide cermet at different temperatures
图 5 不同氧化物钼基金属陶瓷电导率
Figure 5. Electrical conductivity of the Mo-based cermet with different oxides
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