biye非氧化气氛热处理对PTC热敏元件电性能的影响

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1、本科毕业设计（论文）题目：非氧化气氛热处理对PTC热敏元件电性能的影响 学 院 材料科学与工程 专 业 电子科学与技术 学生姓名 彭国林 学生学号 201030290250 指导教师 卢振亚教授 提交日期 2014年 5 月 30 日 摘 要PTC热敏元件由于其特殊的电阻-温度特性、电压-电流特性、电流-时间特性，发挥温度传感、恒温发热、过流保护等功能，被广泛应用于家电、工业控制、航空交通等领域。而PTC热敏元件的生产也从实验室的小规模制备发展到了工业化的流水线制造，动辄上亿的年产量下面埋藏着日积月累数量庞大的不合格废品积压在仓库。论文综述了钛酸钡系PTC陶瓷材料的结构、特性和PTC效应的理论

2、模型，还总结了生产中常见问题以及热处理改变样品阻值的相关研究。 为了减少资源浪费，提高制造厂家经济收益，本论文工作尝试在氮气氛下对阻值不符合标称要求的PTC热敏元件进行不同温度热处理以改变其阻值，并研究其电性能变化规律和物理机理。实验结果发现，氮气氛热处理的确能够有效地改变样品阻值。我们测试了样品的阻抗频率特性，绘出样品处理前后的Cole-Cole图，根据PTC热敏电阻的等效电路推导计算其晶界电阻和晶粒电阻，发现热处理主要是对晶界产生影响。论文还测定了样品其他性能，因为只有其他电性能不受影响或者其他性能指标有所变化但不影响使用的情况下，氮气氛热处理够改变阻值才有意义。实验发现，处理前后样品的温

3、度系数和升阻比k保持稳定，且加压负载20次后，样品依旧没有失效，说明氮气氛热处理改变阻值具有可行性。必须注意的是，根据开关动作特性实验结果结合衰减系数的定义可以发现，阻值越小必然导致开关动作时间越短，但是这并不影响使用。总而言之，氮气氛热处理能够使PTC热敏元件阻值下降，同时不影响其他电性能，但是不同温度处理会有不同结果，且不同型号元件热处理后阻值变化的幅度不同。在实际生产中，可以对阻值偏差较大但其他性能合格的产品进行不同温度的热处理，使阻值改变到符合应用要求的范围，从而减少资源浪费、提高经济效益。关键词：PTC热敏元件、氮气氛、热处理ABSTRACTBecause of thermal el

4、ement's special resistance-temperature characteristics, voltage-current characteristic, current time characteristic, which play a temperature sensor, constant temperature heating, over-current protection function,widely used in household appliances, industrial control, air traffic etc.The PTC th

5、ermistor production have developed from laboratory preparation to the professional and largescale manufacture, at the following billion annual output buried days and months multiplying unqualified waste,which bring a large number of backlog in the warehouse. BaTiO3 based PTC ceramics material struct

6、ure and properties, theoretical model of PTC effect is summarized in the paper, the paper also summarizes the common problems in the production of heat treatment and the change of sample resistance related research.In order to reduce the waste of resources, improve manufacturers' benefit, reject

7、ed products were heat treated at different temperatures in nitrogen atmosphere in order to change the resistance value, and study its regularity and principle. The conclusions drawn from the experiments tell that the samples' resistance can effectively change after nitrogen powder heat treatment

8、. Based on the impedance frequency characteristics of the sample, plot samples' Cole-Cole, then according to the equivalent circuit of PTC thermistor, found that total resistance consists of the grain boundary resistance and the resistance of the grain, heat treatment is mainly occurred on the g

9、rain boundary.The paper also measured other electrical properties, the change of resistance value is meaningful with the other electrical properties are not affected or influence can be neglected after heat treatment. The experimental findings, the samples' temperature coefficient and elevated r

10、esistance ratio remained stable after the experiment, and did not appear invalid after 20 times applied voltage, illustrate change of resistance value after heat treatment in the nitrogen atmosphere is effective. It must be noted that, according to the switching experiment results with the definitio

11、n of the attenuation coefficient, the smaller the resistance will inevitably reduce the switch time, and it does not affect the use.In a word, heat treatment in nitrogen atmosphere can make the PTC thermistor resistance decreased, also does not affect the other electrical properties, but different t