Controllable Preparation And Properties Of Multilayered Amorphous Carbon Film

Amorphous hydrogenated carbon(abbreviated as a-C: H)film is considered as one of the most promising anti-friction and anti-wear lubrication materials because of its excellent properties such as high hardness,low friction coefficient,and good chemical inertness.However,there are some problems such as high internal stress,poor adhesion,and unstable tribological performance.In this article,different types of a-C: H multilayer films were prepared by RF magnetron sputtering technique.The mechanical properties of multilayer films were improved by adding soft metal nanoparticles in the a-C: H sublayers.Its effects on microstructure,surface morphology,mechanical properties,and tribological properties of the multilayer film were studied,and the relationship between the composition-structure-mechanical properties-tribological properties of the films were investigated.The main results are as follows:(1)Si/a-C: H multilayer films with different modulation periods were successfully prepared by RF magnetron sputtering deposition.The interface between the film and the layers was well-bonded.SiC is formed at the interfaceof the multilayer film.With the modulation periods decreased,the hardness and elastic modulus of the film first decreased and then increased..The details are as follows: the hardness of the film with the modulation period of 456 nm is the highest,which is mainly attributed to the integrity of the carbon network;as the modulation period decreases,the integrity of the carbon network is destroyed,however,with the modulation period of the film is further reduced(171 nm),the SiC hard phase increases with the increase of the interface,and the hardness of the film increases.(2)The tribological properties of Si/a-C: H multilayer film in different environments(air,simulated acid rain,NaCl solution).The study shows that the tribological properties of the film in different test environments are quite different: in the air,the friction coefficient of the film is highest,which is mainly related to the hardness of the film;in the simulated acid rain,the friction coefficient of the film is the lowest,which is related to the formation of the silicic acid lubricating phase;in the NaCl solution,the friction coefficient is intermediate cause the sodium silicate inhibits the formation of silicic acid and increases frictional wear.(3)Si/Ag-C: H multilayer films with different modulation periods were successfully prepared by RF magnetron sputtering deposition technique.The hardness and elastic modulus of the film are mainly related to the modulation period and the Ag content.,The film with a modulation period of 512 nm has the highest hardness and elastic modulus,which is mainly attributed to the fact thatthe incorporation of Ag particles have played a role in nano-enhancement,but do not reduce the rigidity and connectivity of the carbon network.The film with the modulation period of 250 nm has higher hardness and elastic modulus,which is mainly attributed to the increase of the SiC hard phase and the appropriate Ag content.(4)In the simulated body fluid,the Si/Ag-C: H multilayer films exhibit good tribological properties.The friction coefficient of the film with modulation period of 250 nm is the lowest,which is mainly related to the frictional chemical reaction(generation of lubricating phase silicic acid)and the lubricating effect of Ag element.(5)Si/Cu-C: H multilayer films with different modulation periods were successfully prepared by RF magnetron sputtering deposition technique.With the decrease of the modulation period,the hardness and elastic modulus of Si/Cu-C: H multilayer films first decrease and then increase.The hardness and elastic modulus of the film with modulation period of 977 nm are the highest.This is mainly attributed to the integrity of the carbon network.The hardness and elastic modulus of the film with modulation period of 414 nm are the lowest,which is mainly attributed to the relaxation of the structure caused by the Cu particles.(6)when the friction coefficient of Si/Cu-C: H multilayer films with the modulation period of 103 nm is the lowest and the most stable in the simulated body fluids,which is mainly related to the tribochemical reactions(generation oflubricating phase silicic acid)and the lubricating effect of Cu.Furthermore,the friction coefficient of the Si/Cu-C: H multilayer film with the modulation period of 984 nm is lower and more stable,which is mainly related to the hardness and the formation of Cu-rich carbon transfer film.