Influence of Gamma Irradiation on Microstructure, Mechanical Properties and Tribological Properties of a-C: H Films

With the development of nuclear energy and nuclear equipment in recent years, more and more attention has been paid to the influence of high-energy particles on the service behavior of lubricating materials under the irradiation environment. In this paper, a-C: H films were deposited by a magnetron sputtering system designed by ourselves and then irradiated by gamma ray source. The influences of Compton effects induced by gamma irradiation on microstructure, mechanical and tribological properties of a-C: H films were investigated. The results showed that the structure of a-C: H films had a change from sp² hybrid C atomic to sp³ hybrid C atomic after irradiation. The breakages of C-H bonds occurred due to the collision of gamma ray and the bonding energy of H atoms in the film reduced. Compared with the pristine samples, the nanometer mechanical properties as well as the internal stress of the irradiated a-C: H film increased significantly. The irradiated film at 13.5 MGy dose observed the local peeling due to the effect of internal stress. In addition, the friction coefficient and wear rate of the a-C: H films were slightly increased induced by irradiation. The comprehensive analysis showed that the effect of irradiation on the frictional properties of a-C: H films was limited, but the increase of internal stress was the key factor limiting their application in the nuclear environment.