Microstructure And Properties Of SiCp/Cu Composites Prepared By Powder Metallurgy

Copper and copper alloys have good thermal conductivity,but limited by strength and heat resistance,their application range is affected.Starting from the development of copper matrix composites with good thermophysical properties,electrical conductivity and mechanical properties,SiCp/Cu composites reinforced with SiC particles were prepared by mechanical ball milling,vacuum hot pressing sintering,annealing and forging.OM,SEM,XRD,DIL402 and other experimental instruments were used to observe and analyze the change process of powder morphology,the change of average particle size and the uniformity of powder after ball milling.At the same time,the microstructure of SiCp/Cu composites was prepared by hot pressing sintering,and the mechanical and physical properties of the composites were analyzed and thoroughly studied.The main research contents are as follows:SiCp/Cu composite powders were prepared by mechanical ball milling process to make the SiC reinforcements evenly distributed in the matrix.The effects of ball milling speed,ball-to-material ratio,ball milling time and process control agent(anhydrous methanol)on the morphology,particle size and uniformity of composite powders in the process of ball milling were studied.The optimal ball milling parameters were selected for subsequent experiments.The experimental results show that the optimum ball milling parameters are 250 rpm,15:1 ball-to-material ratio,10 h ball milling time and adding process control agent anhydrous methanol.It can make the powder particles grind sufficiently and obtain more uniform and fine composite powders,which is beneficial to the subsequent sintering experiments.The SiCp/Cu composite powders with 15:1 ball-to-powder ratio,250 rpm ball-milling speed and 10 h ball-milling time were sintered under vacuum hot-pressing at 700?,750?,800? and 850?.The sintering pressure was 50 MPa and the holding time was 1 h.It can be concluded that with the increase of sintering temperature,the pore size decreases or disappears,and the density of composites increases gradually,from 92.8% to 96.2%.The microhardness of SiCp/Cu composites increased from 154.3HV to 172.9HV with the increase of sintering temperature.The compressive strength and elongation of SiCp/Cu composites can reach 467.45809 MPa and 20.87% at indoor temperature.The thermal expansion coefficients of SiCp/Cu were obtained by measuring different sintering temperatures in the temperature range of 50-500?.With the increase of sintering temperature,the thermal expansion coefficient of SiCp/Cu decreases.The electrical conductivity and thermal conductivity of the composites increase with the increase of sintering temperature.The experimental results show that the thermal conductivity of the material increases from 195.673W/m·? to 221.346W/m·?.The conductivity increased from52.4%IACS to 65.3%IACS.The conductivity and thermal conductivity of the composites increased after annealing.