Effect Of Metal/Metal Oxide Nanoparticles On The Tribological Behavior Of Single Crystal Diamond

Diamond is widely used in tools,bearings,drilling equipment and precision instruments,due to its unique regular tetrahedral structure.He is expected to play a key role in space processing and precision manufacturing.Because of his high strength,good thermal conductivity,high hardness,good wear resistance,low friction,etc.,Diamond is susceptible to adhesion during friction,due to severe conditions such as vacuum,high temperature and stress concentration.The service life and stability of the relevant equipment will be reduced,if the diamond is seriously rubbed.When nano-solid lubricants are added directly to the friction interface,diamond tribological properties can be improved.In this paper,different metals and metal oxide nanoparticles are added to the friction interface to explore the effect of different nano-solid lubricants on the tribological properties of single crystal diamond.research shows:(1)Under dry nitrogen conditions,the diamond is not worn and the friction process is stable.There is no running-in period during the friction process because the stress is reduced.The coefficient of friction is high,about 0.077.After the FCC metal nanoparticles are spread into the interface,the friction coefficient is reduced(0.02 ~ 0.03),and the diamond is subject to large wear due to graphitization.The phenomenon after the interface is filled with molybdenum nanoparticles is similar to the phenomenon of adding FCC metal to the interface.When the interface is filled with tungsten nanoparticles,the friction coefficient is not significantly improved but the wear is reduced to a certain extent.After the interface is spread with titanium nanoparticles,a large friction coefficient and large abrasion are generated,while cobalt nanoparticles do not significantly change the tribological properties of single crystal diamond.Therefore,diamond can be catalyzed by some metal nanoparticles to graphitize,thereby reducing the friction coefficient but increasing the wear rate of diamond.(2)The diamond self-matching pair is worn because when the stress increases during the friction,the friction coefficient is higher during the running-in period but it is significantly reduced when it is stable,about 0.04.When copper oxide nanoparticles are added to the interface,the friction coefficient(~ 0.025)and wear are reduced.After the iron oxide nanoparticles are spread at the interface,the friction coefficient is not significantly reduced due to the rod-like shape of iron oxide,but the wear of diamond is reduced because of the friction reaction film formed.After spreading the zirconia nanoparticles at the interface,no friction reaction film was formed,and the improvement of diamond tribological properties was small.After spreading alumina nanoparticles at the interface,a dense and spherical friction film was generated at the interface,effectively reducing the friction coefficient(~ 0.02)and the wear rate.In addition,alumina can act as a ball bearing at the friction interface to further reduce the friction coefficient.Different metal oxide nanoparticles can promote the formation of friction film and reduce the friction coefficient and wear rate of diamond.