XJIPC OpenIR  > 材料物理与化学研究室
Thesis Advisor常爱民
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Name硕士
Degree Discipline材料物理与化学
Keyword负温度系数热敏电阻 共沉淀法 超声辅助流变相法 两步烧结 一致性

以锰为主的尖晶石结构过渡金属复合氧化物Mn3-xMxO4(M=Ni、Cu、Fe、Co等)具有显著的负温度系数(Negative Temperature Coefficient, NTC)特性,即电阻率随温度升高而呈指数关系降低。随着电子技术的发展,对热敏电阻器的互换精度、测温精度和稳定性提出了更高的要求,因此有必要对材料 电学性能、老化稳定性、一致性的进行进一步研究。 本论文研究了Mn2.1Ni0.9O4两元系材料的微观导电机理,掺入价格相对低廉的铁或镁元素,运用不同的粉体制备方法和烧结工艺,使阻值和B值可在较 宽范围内调节,并在此基础上研究材料的老化热稳定性和一致性,以期获得具有高互换性和良好的热稳定性的NTC热敏电阻材料。具体研究内容与结论如下: (1)采用氧化物湿法球磨制备Mn2.1Ni0.9O4材料体系热敏电阻材料,结合激光粒度分析仪表征和分析粉体粒径,对卧式行星湿法球磨制备工艺进行优 化,获得最佳制备工艺参数。通过分析Mn2.1Ni0.9O4体系NTC热敏电阻在不同温度下的复阻抗谱,得到其晶粒和晶界的均具有负温度系数效应,两者 均为变程跳跃机制。 (2)采用共沉淀法制备Mn2.3-xNi0.7FexO4(0≤x≤1)NTC热敏电阻,研究不同Fe元素含量对陶瓷相结构、电阻率和B值的影响,电阻 率和B值随着Fe含量增大而增大,室温电阻率ρ25℃与B25/50值可分别在2371~16483769Ω?cm和3809~5798K 较宽范围内的进行调节。 (3)将流变相与超声辅助相结合,运用超声辅助流变相法制备Mn1.25Ni0.75MgxO4(0≤x≤0.7)NTC热敏电阻陶瓷材料,结果表明Mg 的含量影响陶瓷相结构、电学性能和老化热稳定性。热敏陶瓷电阻率和B值随着Mg含量增加逐渐增大,室温电阻率ρ25℃与B25/50值可分别在 2325~11341Ω?cm和3881~4029 K较宽范围内的进行调节,通过一致性研究室温电阻率ρ25℃相对平均偏差0.17%~0.94%,B25/50值相对平均偏差范围0.03‰~0.40‰ ,表明超声辅助流变相法使材料混合均匀。 (4)将两步烧结工艺和传统烧结工艺一致性进行对比研究,得到两步烧结工艺和传统烧结制备的热敏电阻室温电阻率ρ25℃最大平均偏差分别为0.94%和 1.13%,B25/50值最大平均偏差分别为0.40‰和0.78‰,传统烧结得到的热敏电阻的室温电阻率和B25/50值最大平均偏差明显大于两步烧 结工艺得到热敏电阻,表明两步烧结法能有效提高热敏电阻一致性,同时对经两步烧结工艺和传统烧结的到热敏电阻的热稳定性进行研究,结果表明两步烧结工艺能 够提高热敏电阻的热稳定性,此外两步烧结工艺制备的热敏电阻具有晶粒尺寸较小、微观结构均匀优点。

Other Abstract

Negative temperature coefficient (NTC) themistors mainly prepared by transition-metal (Mn, Co, Ni, Fe, Cu etc.) oxide are widely used for temperature measurement and control, compensation and suppression of inrush current, owing to their high sensitivity, fine stability and low cost. With the development of electronic science and technology, the higher precision and stability are demanded for the higher requirements of the measurement and temperature control accuracy. So it is necessary to study the electrical properties, ageing stability and uniformity by changing the system composition and process parameters. Wet ball grinding process was studied in this paper and the micro-resistance properties of MnNiO were analysised by using the complex impedance spectroscopy. The range of resistance and B value was enlarged by incorporating the cheaper iron or magnesium. At the same time, the sintering process was improved. On this basis, material aging and thermal stability was aslo studied. This thesis can be summarized as follows: (1) Mn2.1Ni0.9O4 materials were prepared by soild-state reaction method. Combined with the laser particle size analyzer to the powder material characterization and analysis, the best preparation technology parameters were obtained by optimizating the grinding process.Analyzing Mn2.1Ni0.9O4 system NTC thermistor by complex impedance spectra under different temperature, the result shows that the grain and grain boundary have negative temperature coefficient effect, and the grain boundary resistance is smaller than the grain resistance. (2) Mn2.3-xNi0.7FexO4(0≤x≤1)materials were prepared by coprecipitation. It is indicated that the resistivity and B value increases gradually with the content of Fe increased. The parameters of electrical resistivities ρ25℃ and B25/50 value are found to be in the range of 2371Ω?cm to 16483769Ω?cm and 3809K to 5798K. (3) Mn2.1Ni0.9MgxO4(0≤x≤0.7)NTC thermistor ceramic material was prepared by rheological phase reaction with ultrasound radiation method. The Mg contents have impact on the ceramic resistivity, B value and aging of ceramic samples. The ceramics resistivity and B value increased gradually with the increase of Mg content. The characteristic parameters of electrical resistivity ρ25℃ and B values are found to be in the range of 2325Ω?cm to 11341Ω?cm and 3881K to 4029 K. The uniformity research of Mn1.25Ni0.75MgxO4 ceramic samples shows that the resistance value deviations are less than 0.94%, and the B value deviations are less than 0.40‰. This suggest the rheological phase reaction with ultrasound radiation method is a useful technique to prepare the sufficient homogeneity of NTC material powders. (4) The uniformity research of Ni0.9Mn2.1?xMgxO4 ceramic samples sintered by the two-step sintering and traditionary sintering shows that the resistance value deviations are less than 0.94% and 1.13%, and the B value deviations are less than 0.40‰ and 0.78‰. The B value deviations and resistance value deviations of traditionary sintering ceramic are lager than the two-step sintering method. This suggests that two-step sintering process is a useful method to enhance the uniformity of NTC ceramic materials. Furthermore, we investigate the resistance drift of Mn1.25Ni0.75MgxO4 ceramic samples sintered by the two-step sintering and traditionary sintering. The results show that the resistance drift of the two-step sintering ceramic are smaller than traditionary sintering ceramic. This suggests the thermal stability of NTC ceramic can be enhanced effectively by two-step sintering process.

Document Type学位论文
Recommended Citation
GB/T 7714
张丙寅. Mn-Ni-M(Fe、Mg)-O系NTC热敏电阻陶瓷材料制备与电性能研究[D]. 北京. 中国科学院大学,2013.
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