Study On The Preparation Method And Interface Properties Of The Carbon Sliding Plate For High-speed Railway Train With Root-system Interlocking Structure

The high-speed railway is the main artery of the national economy and a popular means of transportation,and plays an important role in economic and social development.With the proposal of the 14 th Five-Year Plan,the economy of China has entered a new stage of rapid development,and high-speed railways are urgently required to have higher speed and larger carrying capacity.The sliding electrical contact of the pantograph-catenary system is the only way for high-speed trains to obtain energy.The carbon sliding plate for the high-speed railway train,as the key current collecting element,is the interface where the pantograph-catenary sliding electrical contact realizes the energy transfer.Its good service performance is the foundation to ensure the safe and reliable operation of high-speed trains.However,with the continuous increase of train speed and the complication of operating conditions,the current carbon sliding plate of the high-speed railway train has gradually been difficult to meet the needs of the operation.There is an urgent need to develop carbon sliding plate materials with higher performance.Up to now,some research works have proved that the internal structure of carbon-matrix composites carbon sliding plate is the key to its performance.Some progress has been made to control its internal structure by selecting a better matrix and filler or optimizing the preparation method.However,with the advancement of research work,the strategy of continuing to improve material properties through the above methods has entered a "bottleneck period".Therefore,more effective structural control research is urgently needed to further improve the comprehensive service performance of the carbon sliding plate of the high-speed railway train.After continuous evolution,natural organisms have the super advantages of structural characteristics.It is an effective strategy to learn and imitate natural biological structures for preparing high-performance materials.However,the raw materials for the preparation of carbon-based composite are complex and difficult to control.At the same time,they have high requirements for low-cost,high-efficiency industrial preparation.The biomimetic structures and their preparation methods reported so far are not suitable for the preparation of the biomimetic carbon sliding plate of the high-speed railway train.Therefore,it is an effective way to obtain high-performance carbon sliding plate by developing a new biomimetic structure and its preparation process.Inspired by the mechanical interlocking between the roots and the soil to maintain the structural stability of the tree,and the structural characteristics of the roots that absorb nutrients from the soil and transmit them efficiently,this paper designs a root-system interlocking structure of carbon sliding plate.A simple,efficient,and environmentally friendly high-speed blending method was used to realize the surface modification of carbon fiber(CF).Moreover,a carbon sliding plate with a biomimetic structure was prepared by utilizing the heterogeneous nucleation properties of the binder pitch.Compared with the pristine CF reinforced composites,the compressive strength(158.33 ± 1.95 MPa)and flexural strength(36.65 ± 1.32 MPa)of the carbon-matrix composites with root-system interlocking structure increased by 101.4% and 65.8%,respectively.A mechanical interlock mechanism is suggested to explain the enhanced mechanical properties of the carbon sliding plate for the high-speed railway train.Furthermore,the electrical and thermal conductivities were also increased in the designed carbon sliding plate.This paper focuses on the key CF@pitch-cokes self-assembly structure in the forming process of biomimetic structure to find out the forming mechanism of the root-system interlocking structure.Based on the self-designed and developed pitch-coke modified AFM probe technology,the evolution law of the intermolecular force between CF and pitch-coke was analyzed.Owing to the effect of adhesion and electrostatic forces,CF and pitch-cokes assemble spontaneously under high-speed blending.The interface morphology and microstructural properties of the CF@pitch-cokes were characterized,and the structural stability was verified.A three-dimensional particle tracking model was constructed to get the influencing factors of CF@pitch-coke structure formation.This provides a theoretical basis for tailoring the root-system interlocking structure of the carbon sliding plate.In order to further improve the performance of the materials,the interfacial characteristics of the pitch-coke and the binder pitch in the root-system interlocking structure were deeply analyzed.A strategy was proposed to use graphene oxide(GO)to modify pitch-coke,and to obtain reduced graphene oxide(r GO)in situ during high-temperature sintering to directionally strengthen the interface of pitch-coke and binder pitch.The low-cost and high-efficiency shear mixing method promotes the interfacial bonding between GO and pitch-coke.Compared with those of C/r GO-0,the compressive strength(203.90 ± 2.85 MPa)and flexural strength(40.53 ± 1.42 MPa)of the C/r GO-0.2 were increased by 112.1% and71.2%,respectively.The deflection effect of r GO on crack propagation and the increase in the interaction energy between the r GO and the matrix strengthen the mechanical properties.At the same time,the friction,electrical and thermal properties of this material are significantly improved.The preparation method and interfacial characteristics of the root-system interlocking structure investigated in this paper have laid a theoretical and technical foundation for obtaining the high-performance carbon sliding plate of the high-speed railway train,and contributed to the development of the high-speed rail industry.