| Carbon fiber fabric reinforced copper matrix composites?Cf/Cu-Ti and Cf/Cu-Zr?were prepared by the method of pressureless infiltration.Titanium powders and zirconium powders were added to improve the interfacial bonding and wetting properties of carbon fiber fabric and the copper phase.The compression performance under high strain rate and the thermo-physical properties of the composite were tested.It is expected to provide theoretical references for the industrial applications of the carbon fiber fabric reinforced copper matrix composites.In this study,the copper matrix to prepare Cf/Cu-Ti composites and Cf/Cu-Zr composites were prepared with pressureless infiltration.Metallographic,SEM,and XRD were adopted to observe the microstructure of the Cf/Cu-Ti and Cf/Cu-Zr samples and analyze the composition of the interface layer.The Cf/Cu composite material with alloying agent has uniform distribution of carbon fibers in the matrix of copper alloy.A good wettability of the fibers by copper matrix is observed and there are no obvious microscopic defects.Alloying agents mainly react with carbon fibers to produce metal carbides?TiC,ZrC?,which are concentrated near the interface layer.The surplus copper in the alloy gradually aggregates into the"rich copper zone"in the diffusion zone of the interface.With the increase of the content of zircon,the porosity of the composite decreases gradually,the thermal conductivity of the material and the thermal expansion coefficient of the material become lower.It is indicated that the alloying agent Zr improves the thermal expansion coefficient of the composite,but it is not conducive to the thermal conductivity of composites.When the Zr content is 30%,the coefficient of thermal expansion of the Cf/Cu composite in the horizontal direction is as low as 5.9×10-6 K-1 at 600°C.The thermal conductivity of Cf/Cu-Zr composites in the horizontal direction is up to 153W/m·K at room temperature.Comparing the calculating values of the theory model with the experimental ones,it is found that the changing trends of theoretical model calculation value and experimental data are similar.The coefficient of thermal expansion decreases with the increase of zirconium content.According to the comparison,the Schapery model and the carbon fiber reinforced copper matrix composite have the closest results with regard to the thermal expansion coefficient.The effect of Ti content on the compression performance under high strain rate was analyzed.The experimental results show that the dynamic compressive strength of Cf/Cu-Ti composites increases with the increase of Ti contents under the same strain rate in the same direction,and the compressive mechanical properties of the composites are obviously improved.The carbon fiber fabric reinforced copper matrix composites exhibited high plastic failure stress and strain softening under dynamic compression with high strain rate.When the strain rate increased from 800 s-1 to 1800 s-1 during the dynamic compression test,the compressive strength of Cf/Cu-30%Ti composites increased from 440MPa to 769 MPa in the parallel direction,indicating that Cf/Cu-Ti composites had a significant strain rate strengthening effect.The failure mode of Cf/Cu composites at high strain rate is interlayer fracture in the horizontal direction,and the V-shaped crack is formed by the 45°shear failure in the vertical direction.However,the failure modes of Cf/Cu-Ti composites mainly exhibit 60°shear failure under quasistatic compressive loading. |
PDF Full Text Request