The Researching On High Temperature NTC Thermosensitive Ceramics Materials

With the development of science and technology, modern society is graduallyentering the era for the Internet of things. Various characteristics of sensor is widelyused. Because NTC thermistor device is easy to use and relatively inexpensive andbecause of its sensitive detection, it is actually the most widely used sensor. Cause theNTC thermistor device performance variables, the development of precision and theelectrical properties of the NTC has some difficulties. Especially high temperatureNTC thermistor devices have an inherent electrical properties of high-temperaturestability and many other issues, domestic manufacturers usually produce NTCthermistors working at the low temperature. There is a big demand for the actual use ofhigh temperature NTC thermistor devices and abroad blockade of highly sophisticatedtechnology and our own research in high temperature NTC material is behind othercountries. So in the preparation of high stability, high sensitivity and high temperatureNTC devices, the domestic technology is relatively backward.Based on the Mg-Al-Cr-Fe-O high temperature NTC thermistor material, want todevelop a high temperature NTC thermal ceramic material by the high temperaturesintering. this paper has researched the influences of Mg, Al, Cr, Fe with different ioncontent on the electrical properties of the material system, and found that increasingthe content of MgO can improve the resistivity value of the material and the B value,and with an30%increase of content of MgO in the base formulation, the resistivitychange more than three orders of magnitude. Increasing the content of Al₂O₃in theceramic sample requires a higher sintering temperature and reducing the content ofAl₂O₃can decrease the temperature of ceramic sintering and increase the resistivity ofthe sample as well as B values.This paper studied the effect of different process parameters on the electricalproperties of system materials and found when we burn materials at1300℃,1350℃,1400℃and1450℃, the lower the temperature, the higher the B value as well as thethermistor value. When milling10h,15h,20h and25h, with the increase in milling time,the proportion of spinel in thermistor and the B value increased. The resistance value of20h of milling is the largest. High temperature holding time is2h,4h,6h,8h.Holding time has a great effect on the resistance. When the sample is sintered for6h,the resistance of the sample is the largest. When thermal insulation time is too short ortoo long, the resistance rate of the sample is reduced.Several times of ball milling andpre-sintering process can reduce the resistance rate of the sample, but the value of thesample B is little influenced.This paper also analyzed how the doped La₂O₃, Y₂O₃and CeO₂can influence thesystem power performancea LaCrO₃crystalline substances with good stability. Dopedquality score of2%La₂O₃can make resistivity reach the largest level. The aging of thesample makes the resistivity and B values increased and B value can be more than10000K.Both doped Y₂O₃, CeO₂can form new substances with oxide in the recipe.They have little effects on the performance of the system samples electricity, unable tooptimize performance.