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研究了150~325℃氮气氛热处理对钛酸钡基PTC热敏电阻电性能的影响。实验结果表明,氮气氛热处理能有效降低样品的室温电阻率。热处理温度从150℃升高至325℃,材料电阻率的相对变化率分别达到约–12%和–70%,但是居里点附近的电阻率温度系数变化不大,样品开关特性随着电阻值的降低而发生相应改变。通过复阻抗谱图分析发现,氮气氛热处理前后样品的晶粒电阻几乎保持不变,而晶界电阻显著减小,表明氮气氛热处理主要对PTC陶瓷的晶界起作用。本研究结果说明可以通过氮气氛热处理的方法调节已经烧结的PTC陶瓷元件的电阻值,使其适合应用要求,从而提高产品合格率。
The effects of nitrogen atmosphere heat treatment at 150 ~ 325 ℃ on the electrical properties of barium titanate-based PTC thermistors were studied. The experimental results show that nitrogen atmosphere heat treatment can effectively reduce the room temperature resistivity of the sample. When the heat treatment temperature rises from 150 ℃ to 325 ℃, the relative rate of change of the material resistivity reaches about -12% and -70%, respectively, but the temperature coefficient of resistivity near Curie point has little change. The sample switch characteristics change with the resistance value The corresponding change has taken place. The complex impedance spectroscopy analysis showed that the grain resistance of the samples before and after nitrogen atmosphere treatment remained almost unchanged, while the grain boundary resistance decreased significantly, indicating that nitrogen atmosphere heat treatment mainly plays a role in the grain boundaries of PTC ceramics. The results of this study indicate that the resistance of the sintered PTC ceramic components can be adjusted by nitrogen atmosphere heat treatment to suit the application requirements so as to improve the product qualification rate.