Study On The Fabrication Of Biomimetic Laminated Graphene Composite Ceramic Cutting Tool And Its Cutting Performance

In order to solve the problem that the mechanical properties and wear resistance of traditional ceramic tools cannot be reasonably balanced,this paper introduces graphene(GNPs),and imitates the"brick-mud"structure of shells,and develops the bionic laminated graphene composite ceramic tool.The ceramic tool is designed as the symmetrical structure,which is formed by alternately stacking surface ceramic tool materials and matrix ceramic tool materials.The mechanical properties of the surface layer and the matrix layer have the vital effect on the performance of bionic laminated graphene composite ceramic cutting tools.Therefore,this paper first studies the surface and matrix ceramic tools,and then studies the bionic laminated graphene ceramic tools in detail.Al₂O₃/TiB₂/GNPs surface ceramic cutting tool material is prepared by the spark plasma sintering technology,and the best sintering process is obtained:the sintering temperature,holding time and sintering pressure is 1525°C,5 min,and 30 MPa,respectively.It is found that the addition of GNPs promotes the densification rate and improves the mechanical properties of ceramic tool materials.Al₂O₃/TiB₂/0.3wt%GNPs ceramic cutting tool material obtaines the best comprehensive mechanical properties,compared with Al₂O₃/TiB₂ ceramic cutting tool material,its fracture toughness increased by 41.6%(7.35±0.23 MPa.m^1/2),its flexural strength increased by6.4%(661±18 MPa),and its Vickers hardness decreased by 5.2%(18.2±0.28 GPa).Al₂O₃/TiN_n ceramic tool materials and Al₂O₃/TiN?are prepared under the above optimum sintering conditions.With Al₂O₃as the matrix,nano TiN(marked TiN_n)and micro TiN(marked TiN_?)as the reinforcing phases,Mg O and Y₂O₃ as the sintering aids.It is found that the fracture toughness is similar(4.47±0.26 MPa.m^1/2 and 4.6±0.3MPa.m^1/2 respectively),but the flexural strength and Vickers hardness are quite different.The flexural strength and Vickers hardness of Al₂O₃/TiN_?ceramic cutting tool materials are high,and the maximum values are 670±32 MPa and 19.1±0.16 GPa,respectively.Therefore,Al₂O₃/TiN_?ceramic cutting tool material is selected as the matrix layer of the bionic laminated graphene ceramic cutting tool material.The bionic laminated graphene composite ceramic cutting tool material is designed by using the finite element software ANSYS.And the influence of layer number and layer thickness ratio on residual stress is studied by establishing its finite element model.Based on simulation results and experiment results of the homogeneous composite ceramic cutting tool materials,Al₂O₃/TiB₂/GNPs-Al₂O₃/TiN?(marked ATBGN)bionic laminated graphene composite ceramic cutting tool materials with different structures are prepared under the above optimal sintering process,and their mechanical properties and microstructure are analyzed.The research shows that the optimal comprehensive mechanical properties of ATBGN are obtained when the number of the bionic laminated layers number is 7 and the layer thickness ratio is 6.Compared with Al₂O₃/TiB₂,the fracture toughness and flexural strength of the front surface of ATBGN are increased by66.7%and 21.5%,and the maximum values are 8.65±0.18 MPa.m^1/2 and 755±25 MPa,respectively.However,the change of Vickers hardness on the front side is not obvious(18.9±0.23 GPa).By analyzing the microstructure of the bionic laminated graphene composite ceramic cutting tool material,it is found that the multi-scale deflection of cracks and the change of the fracture mode occurs under the synergistic action of GNPs and the laminated structure,which is the main reason for the excellent mechanical properties of ATBGN.In this study,40Cr is selected as the workpiece,and the cutting performance of ATBGN is studied.The cutting experiment results show that GNPs and the laminated structure can effectively improve the cutting performance of ATBGN.In the cutting process,GNPs can significantly reduce the friction coefficient.The residual compressive stress on the surface can improve the wear resistance of ATBGN.The effective cutting distance of ATBGN is 6100 m,and its failure forms are mainly the adhesive wear of the rake face,the adhesive wear and abrasive wear of the flank face.