Study On Multiscale Mechanics And Tribological Behavior Of DLC Film In Silicon Nitride Ceramic Bearings

Diamond-like carbon (DLC) films at micro-and nano-scales are widely usedas protective coatings in the industrial fields,especially making a goodperformance on antifriction and wear resistance in ceramic ball bearings.In thisstudy, molecular dynamic (MD) simulations and finite element analysis are carriedout to study the nano-indentation and nanometric scracthing process of DLC filmsand analyze the mechnical and tribological properties of DLC films in ceramic ballbearings.These researches provide the foundation of analysis method on DLCfilms at micro-and nano-scales.The Tersoff and EAM potential are used to describe the interation at the DLCfilm-silicon nitride substrate and DLC film-metal substrate interfacerespectively.Then DLC films are created by the simulation method which ishomogeneous condenstion of a vapor. And considered the cutoff,density andpotential effects on the film identity,decide the appropriate simulated conditionsand make preparation for follow-up work.Substrate has significant influences on the mechnical and tribologicalpeformance of films. In order to study the influences of substrate,film density,filmthickness on nano-indentation and the effects of DLC films, scratch depth onnanometric scratching process,the nano-indentation of DLC thin films on siliconnitride and metal substrate and nanometric scratching processes of DLC films onsilicon nitride substrate is investigated by three-dimensional MD simulation.Thisprovides theory basis to application of DLC film at nano-scale in ceramic bearings.Finite element analysis is carried out to study the nano-indentation of DLCfilms at micro-and nano-scales, and analyze the impact of substrate material,filmthickness,elastic modulus of DLC film,substrate thickness on the mechnicalproperty of DLC film. The variation of mechanical characteristics of DLC filmsvaried from nano-scale to micro-scale is also investigated. Then compare theresults with MD simulation respectively and draw the conclusion about suitableanalysis method on DLC films at micro-and nano-scales.