Investigation Of Load-bearing And Tribology Behavior Of Diamond-like Carbon Multilayer Films

Diamond-like carbon(DLC)film has attracted extensive attention and research due to its high hardness,excellent wear resistance,good optical transparency,excellent chemical inertia,high thermal conductivity and other characteristics.However,its defects,such as large internal stress and poor bonding performance,have not been well solved.To improve these defects,it is necessary to study the relationship between the film properties and the substrate,the transition layer,the friction test conditions and other factors.In the current studies,the damage mechanism of DLC film under loading conditions and the influence law of its structure on the bearing characteristics are not clear yet,and the influence of the insufficient coordination ability of the film with the deformation of the substrate on the tribological behavior remains to be revealed.Based on the above problems,this paper focuses on the analysis of the bearing characteristics of DLC film and its tribological research.DLC films was deposited on SUS304 and YT15 substrates.Al Ti N transition layer is tailored to deposit on half portion of the samples.The microstructure,roughness,hardness,toughness,adhesion property and tribological behavior are systematically evaluated to explore the coating surface evolution in the long-run reciprocating wear.Results indicates that the high hardness substrate can improve the wear behavior of the coating at the early stage of abrasion.Moreover,the I_D/I_G ratio of the DLC coatings deposited on different combinations of the substrates and transition layer tends to stabilize as the abrasion times exceeded 100,000 cycles.The present results promote the scientific understanding and engineering application of DLC films in long-run reciprocating wear.According to the above conclusions,the influence of the transition layer on the bearing capacity of the film was further studied.Using the ANSYS finite element analysis method,design with Ti and Ti C,Ti N,Ti CN material for transition layer of multilayer DLC films,the results show that the maximum Messe stress of DLC film is positively correlated with Young’s modulus of transition layer material.The Mises stress is the minimum when the Young’s modulus of the transition layer material is arranged from upper layer to lower layer.The Mises stress of 1.0μm Ti transition layer DLC film is the minimum 3520 MPa,and it has good bearing capacity.The friction tests of DLC films under different loads and frequencies were studied.When the frequency is 2.5 Hz,the friction coefficient of DLC film is negatively correlated with the load size;When the frequency is 5 Hz and 10 Hz,the result is opposite.Under the low load of 2 N,the friction coefficient of DLC film is negatively correlated with the frequency;Under high loads of 5 N and 10 N,the result is opposite.