The friction and wear properties of matrix graphite in spherical fuel element for high temperature gas-cooled reactor at different temperatures and loads in helium were studied on a QHT-1000 E friction and wear tester.The friction surfaces of matrix graphite were analyzed by scanning electron microscope to investigate the friction mechanism of matrix graphite.There were great differences among the behaviors of matrix graphite at different temperatures in helium.The effect of temperatures on the friction and...