C布预制体C/C复合材料磁电阻特性研究

Studies on Magnetoresistance Character of Woven Fabric Carbon/Carbon Composites

C布预制体C/C复合材料试样经不同温度石墨化处理后,通过X射线衍射法标定其石墨化度,研究其磁电阻特性。结果表明:随着石墨化度的提高,C/C复合材料的磁电阻增大;石墨化度对C/C复合材料磁电阻-位向关系无影响,磁电阻-位向关系是材料本身的特性,不随石墨化度、磁场强度、测量温度等因素的变化而变化,实验用材料最大磁电阻出现在90°位向处;固定磁场强度,不同石墨化度试样的最大磁电阻随测量温度(5～300K)的增加线性降低;测量温度高于5K,外加磁场小于1.2T时,磁电阻随磁场强度的增大线性增大,场强高于1.2T后,磁电阻不再随磁场强度的增加而变化;测量温度在4.2K时,磁电阻随外加磁场的变化会出现量子化平台。

The carbon/carbon composites with cloth precursor were graphitized at various heat treatment temperature (HTT) and their graphitization degree g was determined by X ray diffraction method The magnetoresistance (MR) properties as functions of orientation angle (φ),measurement temperature (MT) and magnetic field (B) were investigated The results show that under the experimental conditions, the increase of graphitization degree results in the increase of composites magnetoresistance,but has no effect on the relation of MR with orientation, which is also not affected by measurement temperature and magnetic field intensityMR decreases linearly with the increase of measurement temperature at 5~300K in a constant magnetic field intensityIn the range of 0~12 T, MR increases with the increase of the magnetic field intensity in the temperature area of 5~300K, until above 12T,MR no longer risen At 42K, the MR,which is changed with magnetic field, presents quantum phenomenon 