Tailoring Microstructure,Mechanical And Tribological Performance Of Carbon/graphite Materials Based On Sulfonated Graphene

Carbon/graphite materials are an important basic industry of our national economy.It is widely used in aerospace,aviation,energy,metallurgy,automobiles and other core fields because of its unique properties such as self-lubrication,corrosion resistance,electrical conductivity,thermal stability,and thermal stability,However,the typical structural defects of heterogeneous,porous,multi-component in carbon/graphite materials are different from homogeneous materials that have undergone melting and secondary bonding.In addition,during the preparation process of carbon/graphite materials,stress release and binder phase pyrolysis and polycondensation reactions are involved,which lead to the participation of low molecular weight gases as the product escapes the matrix,resulting in the formation of inhomogeneous and random pores and irregular crack defects inside the material.At the same time,the severe service conditions also can easily lead to the expansion of congenital microcracks in the carbon/graphite materials.At present,the regulation of the microstructure of carbon/graphite materials,minimizing their internal defects and realizing the matching of the aggregate phase and binder phase is one of the hotspots and difficulties in related research.In view of the existing defects of carbon/graphite materials such as the mechanical and tribological properties can not be simultaneously improved.We take the picth-based and resin-based carbon/graphite materials as the research object in this paper and regard the“structure design-preparation method-force and tribological properties test-microstructure characterization analysis-mechanism explained”as the main research line.The two-dimensional structure of sulphonated graphene(SGO)is used as a skeleton between different carbon phases,the sulfonic groups of SGO is used as the branch to connect the other carbon materials,which builds the new structure of“skeleton-branch”between reinforcing phase of aggregate carbon and matrix phase of binder.At the same time,the influence and tailoring mechanism of SGO on microstructure,mechanical and tribological properties of carbon/graphite materials are clarified.The main conclusions are as follows:(1)The carbon/graphite materials was prepared by hot extrusion and once baking process which different from the traditional processes of several times of impregnation and roasting leaching.It was found that the introduction of SGO effectively improved the internal structure density and surface integrity of the pitch-based carbon/graphite materials,especially when the added amount of SGO was 1 wt%,the flexural,elastic modulus and compressive strength of the pitch-based carbon/graphite materials are about 2.6 times,2.4 times,5 times the raw materials,respectively.And the weight loss resistance of the composite is significantly better than that of the sample without SGO.The oxidative decomposition temperature of the materials is increased by 90?,while the coefficient of friction is reduced by about 1 times.(2)The resin-based carbon/grphaite materials was prepared by the processes of later impregnated SGO and second curing after pore formation.It was found that the introduction of SGO can reduce current-carrying discharge from the grade of 11/2-2 to the 1-11/4 grade,and effectively reduce the current-carrying wear rate from 0.32 mm/h to 0.14 mm/h,so the service life of resin-based carbon/graphite materials is improved nearly 1.3 times longer than before.Atomic force microscopy results show that the elastic modulus of the material is increased 1.5 times under the action of sulfonated graphene,and simultaneously improve the integrity and consistency of the microstructure of the materials.(3)The results shows that SGO builds a new“skeleton-branch”structure between reinforcing phase aggregate carbon and matrix binder based on its own structure and functional groups on the surface.The new structure effectively inhibits the formation and expansion of internal structural defects in carbon/graphite materials,and assists in the formation of“fish scale”progressive friction film on the wear surface of carbon/graphite materials,achieving the simultaneous enhancement of strength and tribological properties of carbon/graphite materials.