石墨造孔PTCR性能和结构的研究

Research of the Properties and Structure of the Graphite Porous PTCR

对采用规模工业级原料取得的石墨造孔PTCR的工艺技术、性能和微观结构进行了全面的研究和探讨 .当石墨的质量分数为 1 .0 %时 ,采用快速升温、自然冷却的方法 ,可得到室温电阻率低 (2 0～1 0 0Ω·cm)、升阻比高 (≥ 1 0 5)、温度系数大 (2 1 % /℃ )的热敏电阻 ;通过对样品微观结构的分析 ,提出了多孔PTC效应主要起因于晶界氧的吸附 ,而晶粒细小并非是必需的条件的观点 ,并借助Heywany模型作了进一步的理论解释 .

The technique, properties and microstructure of the graphite porous PTCR that is prepared by using commercial materials are introduced and researched in this paper.When the graphite addition is about 1.0% mass fraction,the samples with olw room temperature resistivity (20～100 Ω·cm),high resistivity ration (≥10 5),large temperature coefficient (21%/℃) are obtained by using the way of fast heating and natural cooling.Through the analysis of microstructure to the samples,this paper presents that the PTC effect of porous PTC ceramics is mainly come from the chemisorbed oxygen boundary, and the small grain size of the BaTiO 3 PTC thermistor is not essential to this excellent PTC behavior.With the aid of Heywany model,the author gives some theoretical explanations.