Study On The Preparation And Performance Of Three-dimensional Graphene Reinforced Copper Matrix Composites

Due to its unique mechanical and electrical properties,graphene with two-dimensional structure has attracted wide attention in the research of Cu matrix composites.It is considered as an ideal reinforcement for Cu matrix composites.In order to obtain graphene reinforced Cu matrix composites with excellent properties,it is very important to obtain graphene with uniform dispersion,structural integrity and good interface with copper matrix.At present,most of the graphene reinforced copper matrix composites are prepared by the addition method,however,the graphene prepared by this method shows many defects,such as incomplete structure and poor interface bonding with the matrix due to the agglomeration,which greatly reduces the mechanical and electrical properties of the copper matrix composites.Therefore,it is of great significance to explore a new process route to break through the existing limitations and prepare high performance copper matrix composites.In order to solve the above defects and achieve high-quality graphene/Cu composites,graphene reinforced Cu matrix composites were prepared by powder metallurgy and in-situ chemical vapor deposition(CVD).Two different processes were used respectively.One is reducing the oxidized copper powder in Hz atmosphere,which then forms nanoporous Cu(np-Cu)powder.Using the above np-Cu as matrix,graphite hydride(HG)is grown by CVD method at low temperature,after pressing to bulk np-Cu/HG,pyrolyzed at high temperature.Finally,graphene reinforced Cu matrix composites were prepared by isostatic annealing and re-pressure sintering,the other method is to directly press Cu powder into sheets,and deposit HG on bulk porous copper at low temperature,after pyrolyzing the HG at high temperature and rapidly cooling to room temperature,finally,graphene/Cu composites are prepared by cold rolling and annealing.The effects of two different methods on the morphology and structure of graphene were studied.At the same time,we also researched the effect of in-situ CVD method on mechanical and electrical properties of Cu/graphene composites and their reinforcing mechanism.The results showed that graphene/Cu composites with three-dimensional and continuous structure with excellent properties were prepared by in-situ CVD method.The pyrolysis temperature of carbon source,initial and re-pressing pressure,different rolling reduction,gas flow ratio and HG deposition time were optimized.In the first method,the uniform dispersion and structural integrity of graphene in copper matrix were achieved by the composites prepared with np-Cu powder as the matrix.When the conductivity of composites is 96%IACS(International Annealed Copper Standard),while the tensile strength is 243 MPa,which is 27.89%higher than that of pure copper.On the other method,the composites prepared directly with copper powder as the matrix,not only the uniform dispersion and structural integrity of graphene were realized,but also the three-dimensional continuity of graphene was achieved and the good interface bonding between graphene and copper matrix was maintained.The conductivity of the composites can keeps as high as 113.4%IACS,which is equivalent to pure Cu,moreover,the tensile strength is 261 MPa,which is 49.1%higher than that of pure Cu.