Anti-Wear Characteristics of Carbon Nitride Thin Films

The carbon nitride has been proposed theoretically with a possible structure of β -C3N4, which have replaced Si of β -Si3N4 with C, by Liu and Cohen in 1989. It was announced that β-C3N4 had a higher bulk-modulus value than that of diamond. The research in forming C-N compounds has been actively done. Recently, it has been reported that carbon nitride film has showed a unique property, such as a high elastic recovery compared with DLC film, even if a structure of this film was amorphous. In this study, carbon nitride films have been deposited by means of the magnetically enhanced plasma ion-plating equipment. The following two methods of the deposition were investigated. One is the reactive ion-plating which is a reactive evaporation between carbon vapor and nitrogen plasma. The second is a method of an ionized evaporation caused by mixed gas plasma using hydrocarbon and nitrogen gases. Wear performance and deformation energy evaluation of the films were examined by the micro-wear and nano-indentation tests using AFM device having a peculiar transformer head added to the measuring units. Moreover, crystal structure and chemical composition of the film have been analyzed using FT-IR and XPS, respectively. The film formed with the ionized evaporation using C2H2-Ar-N2 gas plasma showed that the hardness becomes harder than that of the film formed with the reactive ion-plating, due to the confirmation of C-N bonding structure from the result of FT-IR and XPS. When the film is formed under CH4-N2 gas plasma, it has been observed that no micro-wear of the film was occurred, resulting in showing good wear resistance. This is understood that the film shows large elastic recovery from the result of the deformation energy evaluation.