Influence of graphitization treatment on the characteristic of magnetoresistance of carbon-carbon composites

The magnetoresistance characteristics of C/C composites graphitized at different heat treatment temperature (HTT) were investigated. The magnetoresistance of C/C composites exhibits a maximum at 45° orientation angle. HTT, intensity of the magnetic field (H) and the measuring temperature (MT) do not change the profile of the magnetoresistanceorientation curves. Magnetoresistancetemperature curves in the same magnetic field are straight lines with negative slopes. The magnetoresistance of samples formed at lower HTT is zero when MT is high enough. However, the magnetoresistance of the sample formed at HTT of 2?880?℃ shows a saturated value when MT is low enough. From the fitted straight line from magnetoresistancetemperature curves, it is found that the slope decreases and the intercept increases with increasing HTT. The magnetoresistance of C/C composites increases with the increasing magnetic field intensity at the same MT. The curves are parabolic when H is less than 1.2?T and straight when H is higher than 1.2?T. Magnetoresistance increases with increasing HTT in any intensity of the magnetic field.