Study On Properties Of Barium Titanate Based Positive Temperature Coefficient Ceramics With High Curie Temperature

With the improvement of the performance requirements of various electronic products for PTCR components,it is more urgent to make further research on PTCR ceramic materials in order to improve the PTC effect and increase the breakdown voltage.This project comes from the cooperation project"Research on PTCR withstand voltage and aging characteristics"with Haining Yongli Electronic Ceramics Co.,Ltd.In order to solve these problems,this paper studied the formulation and workmanship to improve the product performance.This paper mainly compared one-step synthesis method and two-step synthesis method in solid-state synthesis.The results show that the samples obtained by one-step synthesis method have better PTC effect,but those obtained by two-step synthesis method have higher breakdown voltage.In addition,the liquid phase crystallization granulation method was proposed to improve the uniformity of the powder.It is found that the effect of liquid phase crystallization granulation is related to the drying time of the powder.In this paper,the effects of different sintering methods on the properties of Ba Ti O₃ based PTCR thermistor ceramics were studied.This paper mainly studied the effects of silica and alumina in sintering aids on the properties of Ba Ti O₃ based PTCR thermistor ceramics.It is found that when the content of alumina exceeds a certain amount,the increased introduction of alumina will improve the PTC effect of PTCR thermistor ceramics.Through the experimental study,the high performance ceramic chip with size of 32mm*12mm*2.5mm and the resistance of 2-3kΩwere obtained.The temperature coefficient reached 35.93%,the PTCR jump reached 4.278orders of magnitude,and the breakdown voltage reached 900V.In this paper,the PTCR heater made of the high-performance ceramics was tested by dry-burning-aging test and voltage-withstand test.It is found that after 500 hours of dry-burning-aging,the room temperature resistance of the PTCR heater changed by more than45%,but the working power with wind attenuated less than 6%,but the breakdown voltage was reduced to 650V.