Preparation And Toughening Of Metal-doped Diamond-like Films

Diamond-like carbon(DLC)film has a promising tribological application in green precision manufacturing,but its toughness issue is in the way of its application perspective.In this paper,we use metal doping to improve the film toughness,firstly,we prepared Cr-doped DLC films with different doping contents by medium frequency magnetron sputtering,during which the relationship between Cr doping amount and film hardness and film base bonding was investigated;we prepared Cu-doped DLC films with different doping contents,and the relationship between Cu doping amount and film hardness and film base bonding was investigated;we characterized the film toughness from both energy and stress The toughness of the films was characterized in terms of both energy and stress,and the failure and toughening mechanisms of DLC films were proposed from the change pattern of layer structure of doped non-carbide metals.(1)The influence of different doping content of Cr on the hardness of DLC film and the bonding force of film base was explored.Cr-DLC films with different doping contents were prepared by medium frequency magnetron sputtering method.The phase structure,the structure of the valence bond,the roughness of the surface,the hardness and base of the films have been characterised.With the increase in doping content,the hardening first increases,then decreases and the doping amount at Cr is up to 9.3 at.%at a maximum value of 10.5 GPa.The binding strength of the film base increases first and then decreases,and the maximum binding strength reaches 11.5 N when the doping amount of Cr is 14.6 at.%.(2)The influence of different Cu doping content on DLC film hardness and film base bonding force was explored.The Cu-DLC films with different doping contents were prepared by medium frequency magnetron sputtering method.The phase structure,valence bond structure,surface roughness,hardness and film base bonding force of the films were characterized.The results show that with the increase of doping amount,the content of sp~3-C bond in the film increases first and then decreases.The hardness increases first and then decreases,and when the Cu doping amount is 10.4 at.%,the hardness reaches the maximum of 7.9 GPa.The film base's binding strength increased first and then decreased to 12.7 N when the Cu doping amount was 10.4 at.%.(3)To investigate the characterization method and toughening mechanism to accurately characterize the toughness of thin films.By comparing the toughness performance of DLC films before and after doping by impact and scratch methods,a characterization method is proposed to explore the toughness of films from both stress and energy aspects,and the combination of impact toughness and scratch toughness of films can reflect the complete toughness of films;the toughening mechanism of films is revealed by analyzing the change patterns of film structure and properties at different stages of films.Mechanism II,IV and V are considered to be the main driving forces for toughening.