Preparation And Performance Study Of Copper/graphite-based Nanocomposites By Magnetic Levitation Collision Grinding-hot Pressing Synthesis Method

Modern materials science research is developing rapidly.The development of human life also puts forward higher requirements for material science research.The application of materials in the fields of electronics,information dissemination and intelligence has become more and more extensive,and some new material requirements have followed.Under this background,Cu graphite-based composites show unlimited application prospects.Magnetic levitation collision grinding technology as an advanced micro-nano-powder grinding technology has great advantages in the preparation of new materials at this stage.Therefore,the main purpose of this study is to prepare copper-graphite composites by using magnetic levitation collision grinding technology.In this paper,a new copper/graphite matrix composite is prepared by magnetic suspension collision grinding and hot press forming.Scanning electron microscopy（SEM）and X-ray energy dispersive spectroscopy（EDS）were used to observe the morphology and element distribution of micro-nano powders.X-ray diffractometry（XRD）and micro-Raman spectroscopy were used to analyze the phase composition of micro-nano powders.According to the obtained results,the ball milling parameters of ball ratio,rotation speed,ball milling time and Cu/C ratio are adjusted,and a set of optimal process parameters is selected.Then,TiB2 prepared by the sol-gel method is added to the Cu/C-based powder,and then the powder is densified by a vacuum hot pressing process to form a bulk microcrystalline composite material.By adjusting the parameters such as sintering temperature,molding pressure and holding time,the optimal hot press forming process parameters were optimized,and Cu/C/TiB₂ composites with excellent hardness and electrical conductivity were prepared,and the following conclusions were obtained.（1）For copper/graphite matrix composites,the optimum process parameters for magnetic suspension collision grinding powder are:optimal time for magnetic suspension collision grinding is 3 hours,and Cu/C nano powder with optimal C content is 1%.More suitable for subsequent vacuum hot press forming.（2）With the prolongation of time,Cu/C particles showed obvious mechanical alloying,Cu/C particles were welded and agglomerated,and the agglomerated particles experienced process of welding-refinement-re-welding.At the same time,the increase of C content is beneficial to the refinement and lamination of the particles.（3）For the densification molding operation of the nanocomposite powder,vacuum hot pressing sintering is employed,and the hot pressing temperature of the vacuum hot pressing sintering is 850℃,the heating rate is 10℃/min,the holding time is 2 h,and the molding pressure is 60 MPa.（4）The increase of TiB₂ content is beneficial to the improvement of the hardness of the material,but the conductivity of the material is somewhat reduced.The participation of C in Cu/C/TiB₂ has a certain degree of improvement in hardness and electrical conductivity.The Cu/C/TiB₂ composite with TiB₂ content of 3%has the best hardness and electrical conductivity.