Design And Performance Study Of MoS₂ Based Solid Lubricating Film

Mechanical motion systems play an indispensable role in various types of equipment.But the inevitable friction at the motion interface often leads to a large amount of energy waste and economic losses.At the same time,severe wear also shortens the service life of components and even trigger safety accidents.The simultaneous realization of friction reduction and wear resistance through material design and environmental matching is of great significance for the development of the field of tribology.Molybdenum disulfide（MoS₂）,as a two-dimensional van der Waals material,has a unique layered structure and exhibits excellent weak shear properties.Especially in vacuum environments,sputtered MoS₂ solid lubricating films have been successfully applied to precision components of space telescopes,assisting humans in exploring the mysteries of the universe.However,in the atmospheric environment,MoS₂ is easily oxidized to form highly brittle Mo O₃ crystal particles with abrasive properties,leading to the destruction of the van der Waals sliding of the layered structure and hindering the effectiveness of MoS₂ as a lubricant in the atmospheric environment.In addition,MoS₂ with low mechanical strength exhibits weak wear resistance,thus its service life is often not long,greatly limiting its application under high load and other service conditions.Therefore,it is urgent to develop high-performance MoS₂ based solid lubricating films and optimize their tribological properties under various complex conditions.The high performance of solid lubricating films is reflected in the balance between lubricity and durability,that is,achieving high hardness and low shear strength simultaneously.This is the main challenge we face in constructing MoS₂ based solid lubricating films that can be widely used in complex environments.This paper focuses on MoS₂ films as the main research object,aiming to address the key issues of unavoidable oxidation failure,difficulty in balancing lubrication and durability,and difficulty in breaking through performance bottlenecks.Through component control and structural design,the performance of MoS₂ based lubricating films is optimized,and a solid-liquid composite lubrication system with superlubricity characteristics is developed by coupling with the environment.The combination of experimental characterization and theoretical simulation in the research process has deeply explored and explored the mechanisms behind all experimental phenomena,and the following innovative results have been obtained.1.Introducing Nb into MoS₂ films based on enthalpy strategy to induce amorphous oxidation triboproducts,solving the application challenge of MoS₂ films being prone to oxidation failure.To suppress the oxidation of MoS₂ films in the atmospheric environment,which leads to the formation of highly abrasive Mo O₃ crystal grains and lubrication failure,and meet the needs of high-performance MoS₂ based solid lubricating films to maintain effective lubrication in all environments of space scenes,we propose the“enthalpy induced amorphous oxidation products”strategy.Based on mixed enthalpy and first principles calculations,transition metal Nb elements that can provide amorphous formation ability are selected,and MoS₂-Nb films are experimentally grown.When sliding in the atmosphere,MoS₂-Nb films uniformly dissolve O atoms on the contact surface.Subsequently,the precipitation and transfer of MoS₂ layered lubrication structure are completed under the action of shear force,load,and heat.The MoS₂-Nb films turns the originally negative oxidation process into a beneficial one,inducing self-assembly at the contact interface to form a unique structure of amorphous metal oxide wear-resistant layer on the bottom and two-dimensional layered lubrication layer on the top,thereby achieving a balance between ultralow friction（coefficient of friction 0.02-0.05）and low wear(wear rate 10^-8-10^-7 mm³/N·m)in multiple environments.2.Designing and preparing dual-phase nanocomposite MoS₂-TiB₂ film with lubrication-antiwear,cracking the difficult balance between material lubrication and durability.Low friction demands low shear strength from materials,while low wear puts the expectation on the high hardness from material.However,this contradictory characteristic is often difficult to present simultaneously in materials,resulting in a dilemma of balancing lubrication and durability.To overcome this limitation and combine high hardness and low shear strength,we construct the“dual-phase nanocomposite structure”film and designed a MoS₂-TiB₂ film with coexistence of amorphous and nanocrystalline phases.The TiB₂ hard structural framework resists normal loads and reduces the rapid consumption of MoS₂ during wear,thereby improving its wear resistance.The precisely controlled excess B atoms spontaneously fill the S vacancies,enhancing the integrity of the layered structure of the film and optimizing its tribological performance in the atmospheric environment.,It can balance ultralow friction（coefficient of friction of 0.03）and low wear(wear rate of 10^-7mm³/N·m),even under high load,high temperature and multiple counterparts.MoS₂-TiB₂ film fully leverage the advantages of lubricating and reinforcing phases,establishing a paradigm for designing and manufacturing a class of durable self-lubricating films suitable for various application scenarios.3.Proposing a design concept for the in-situ formation of fullerene like carbon through tribocatalysis of MoS₂-TiB₂ film in lubricating oil,breaking through the performance bottlenecks of superlubricity and ultralow wear.To achieve ideal durable superlubricity under complex and harsh macroscale working conditions,we have constructed a“secondary directional tribocatalysis”route,coupling the MoS₂-TiB₂ dual-phase nanocomposite film mentioned above with the classical PAO 10 base oil lubrication environment.Based on their intrinsic functions,MoS₂ and TiB₂ in the film also show surprising tribocatalytic characteristic.Specifically,TiB₂ provides the ability to extract carbon sources from oil,while MoS₂ induces the ordering of amorphous carbon and promotes the in-situ formation of fullerene like carbon tribofilms.This solid-liquid composite system has achieved excellent performance in macroscale ultradurable superlubricity（coefficient of friction 0.007）and ultralow wear(wear rate 10^-9 mm³/N·m)under high contact pressure of hundreds of megapascals and long sliding distance of over 10 kilometers.This study provides an effective strategy for developing high-performance superlubricity and ultra wear-resistant lubricating materials,providing new possibilities for the implementation of superlubricity technology in engineering applications.This paper investigates the interaction and tribological behavior between MoS₂and transition metals,hard ceramics,and oil-based lubricants from the perspectives of component control,structural design,and environmental coupling,including enthalpy induced amorphous oxidation products,lubrication-antiwear dual-phase structure design,and solid-liquid coupling tribocatalysis.This paper contributes to deepen understanding of MoS₂ lubricating materials and provides key information for the promotion of MoS₂ based lubricating materials to practical applications in various fields.