Study On Microstructure And Properties Of Diamond/Cu Matrix Composites

Copper as well as copper alloy is a kind of important metal structural material and functional material.They are widely used in the fields of machinery industry,electronics,aerospace etc.However,with the development of technology,the requirements for the performance of material are boosting.Copper and copper alloy have been unable to meet the requirements on the properties of materials.Copper-based composites not only have high thermal and electrical conductivity but also make up for their lower strength,poor abrasive resistance and high-temperature behavior.So copper-based composites are widely applied in electronic packaging,electrical brushes,electrical contacts,resistance welding electrodes and other fields.Diamond has the highest hardness among all nature materials,and also has high abrasive resistance,low thermal expansion coefficient and other excellent performances.The copper-based composites with excellent comprehensive performance were prepared by adding diamond.In this paper,micro-diamond(MD)/Cu-matrix and nano-diamond(ND)/ Cu-matrix composites are prepared by SPS method.The effect of diamond content on tensile strength,thermal conductivity,hardness and wear resistance of the composites are studied.The distribution of the diamond,the combination of the interface,the fracture morphology and the wear morphology are observed by scanning electron microscope,and the element analysis of wear debris is analyzed by using energy spectrometer.The results show(1)With the increase of MD content,the tensile strength of composites increases first and decreases later.When the content of MD was 1wt%,the highest tensile strength of the composites was 221.35 MPa.When the content of MD is 2wt%,the highest thermal conductivity of the composites is 333W/(m·K).The addition of diamond can significantly improve the hardness of the composites,the highest hardness is 117.436 HV,increased by 85.6% compared with the pure copper.(2)With the increase of the content of nano-diamond,the thermal conductivity and tensile strength of the composites are decreased.The hardness is increased first and decreased later,the highest hardness is only 77.384 HV.Nano-diamond is mainly distributed at the grain boundaries.The copper matrix presents a network distribution,and the matrix is seriously separated.(3)The addition of micro-diamond can significantly improve the wear resistance of composites.The lowest friction coefficient is only 0.388,decreased by 45.3% compared with pure copper.The main wear mechanism is oxidative wear.The wear resistance of nano-diamond /Cu composites is poor.The highest friction coefficient of the composites is 0.892.The main wear mechanism is delamination wear.(4)The wear resistance of MD/Cu composites increased mainly because of the substrate to form a layer of oxide film and the mechanical mixed layer,with the increase of load,the friction behavior of the composites from oxidation wear to adhesive wear,along with the increase of speed,composites from oxidation wear to adhesive wear,and then change oxidative wear.