Research On Wet Friction And Wear Properties Of Carbon Fabric Composites

The wet friction materials with the excellent friction and wear properties are widely used in the fields of aviation,ship,engineering machinery and automobile.With the development of industrialization technology,the power,speed and load of vehicles and equipment are increasing,and the work conditions of wet friction materials are becoming more and more severe.The mechanical strength and heat resistance of traditional wet friction materials are constrained by material composition and preparation process.It is difficult to meet the requirements of extreme conditions such as high-speed and heavy-load.There is a pressing need to develop new high performance wet friction materials.Carbon fiber has high specific strength,high specific modulus,high temperature resistance and outstanding wear resistance.As a reinforcing material,carbon fabric is expected to greatly improve the thermal performance,load bearing capacity and tribology properties of wet friction materials.Carbon fabric reinforced resin-based composites(referred to as carbon fabric composites)are recognized as a new type of wet friction material with great development potential and broad application prospects.Due to the textile structure of the carbon fabric,the composites surface is covered with textile texture.The local bearing of the convex portion of fiber bundles during the friction process is easy to cause the brittle fracture of the fiber bundle which can cause friction coefficient fluctuation and severe wear.Thus the excellent friction performance of the carbon fiber is difficult to function normally.In order to promote the application of carbon fabric composites in the wet friction field,improving the surface morphology and improving the wet tribology properties of carbon fabric composites are challenges that urgently need resolving.Based on that,the research focuses on the friction modification and application of carbon fabric composites under two typical wet friction conditions of oil lubrication and water lubrication.The study deploys from the following aspects: The graphite modified carbon fabric composites were prepared by the impregnation process.Through the test and analysis of thermophysical properties and wet friction and wear data,the effects of key parameters such as graphite content and graphite particle size on wet friction properties of carbon fabric composites under oil lubrication conditions were studied.The synergistic effect of graphite particles and carbon fibers,as well as the influence of the wear mechanism of carbon fabric composites were found and revealed.In view of the problem that the lubricating property of graphite can be affected by humidity,the carbon fabric composites were modified by molybdenum disulfide.The effect of molybdenum disulfide content on the wet friction and wear properties of carbon fabric composites under oil lubrication conditions was studied.Through the characterization of the composition of the friction surface and the valence state transformation,the tribochemical reaction of the friction surface was studied,and the wear mechanism of the metal pair was revealed.The silicon carbide nanowire modified carbon fabric composites material were prepared by insitu growth of silicon carbide nanowires,which solved the problem of dispersion of nanomaterials in the modification process of carbon fabric composites.The effects of precursor content on the growth morphology of silicon carbide nanowires,the interlaminar shear strength of composites and the wet friction and wear properties of carbon fabric composites under oil lubrication conditions were investigated.The wear mechanism of the silicon carbide nanowire modified carbon fabric composites was discussed.A water-lubricated rock friction test platform was designed and builted.Diamond,boron carbide and silicon carbide micropowder were used to prepare modified carbon fabric composites.The influence of particle types,diamond micropowder content and diamond micronized particle size for shear strength and tribology properties were studied.The friction and wear mechanism of carbon fabric composites under water-lubricated rock friction conditions was revealed.As a key component of the electromagnetic measurement while drilling(EM-MWD)system,the measuring short section has high requirements for non-magnetic and wear resistance.Through the research on the composite connection scheme,the bonding influencing factors and the winding forming method,the hard particle modified carbon fabric composites were sucessfully applied in the measurement short section.The electromagnetic measurement function and the wear resistance of carbon fabric composites measuring short section were tested by horizontal directional drilling field tests.It confirmed the scientificity and effectiveness of this research.Meanwhile,the wet friction application field of carbon fabric composites has been broadened.