Effect Of Electron Beam Irradiation On The Structure And Mechanical Properties Of Carbon Nitride Films

Amorphous carbon nitride films have attracted the attentions of various investigators due to their great physic properties and wide range of promising applications such as protecting coatings, electronic devices and biomedicine devices. Irradiation is one of the most commonly used techniques for tailoring materials'properties. In this paper, carbon nitride films were fabricated by a dc facing-target magnetron reactive sputtering system, and then the prepared samples were irradiated by electron beam. The effects of electron beam irradiation on the structure and mechanical properties of carbon nitride films have been carefully studied.As the structure characterization shows, with the increase of nitrogen partial pressure (PN), the nitrogen content (CN) in the films increases from 8.9% to 22% firstly, and then decreases gradually, the content of sp3 bonding decreases and the number and size of sp2 clusters increase, graphitization occurs in the CN films. After electron beam irradiation the CN in films prepared at different PN conditions increase variously because of the oxide and nitride effects occurring at the surface. The maximized CN reaches 25.4%. The bonding structures at the films'surface have changed a lot after irradiation. The bond breaking event and displacement event take place when electron beam is introduced into the films .The sp3C bonds are break, and change to the unsaturated sp2C hanging bonds. When these sp2 bonds connect with each other, sp2 clusters form. Graphitization behaves more deeply in the films.The results of nanoindention tests indicate that the hardness of films decrease from 17.9 GPa to 14.4 GPa firstly, and then increase gradually, which is contrary to the trend of CN vs. PN. The hardness decreases after electron irradiation, which is consistent with the change of structure.