Research On Box Part With High Volume Fraction SiC_p/Al-6061Al Forming And Joining In Semi-solid State

As a connectable electronic packaging shell, the high volume fraction Si Cp/Al-6061 Al box part, with characteristics of high thermal conductivity, low thermal expansion and low density, can provide mechanical support, sealing protection and cooling channels for the internal electronic components. In this paper, the forging and joining integration technology of semi-solid for composite is used to research the near net shape process of the high volume fraction Si Cp/Al-6061 Al box part, and explore the influence of different Si C body fractions, particle sizes and process parameters on the thermo-physical properties, the mechanical properties, the density and the joining effect of the box part.The major processes of the forging and joining integration technology of semi-solid for composite include powder pretreatment, powder mixing and milling, cold forming, thermoforming, secondary remelting, forging and joining. The main experiments include: the pretreatment of Si C powder to improve the dispersion of powders. Prepare five different groups of mixing powder mixed with pure aluminum powder to obtain different body fractions of Si C(50vol.%, 55 vol.% And 60 vol.%) and different particle sizes(14μm, 48μm and 14/48μm) of Si C, and then mix and mill the powder with a uniform purpose. Forg the mixing powder in normal temperature with 6061 aluminum frame together by steel mold, and then obtain the thixofor med semi-solid billet with good density and three-dimensional Al communication through the thermoforming process. Finally, forg and connect billets under different heating temperatures, holding time and molding pressures to obtain the final box part.Through the comparison and analysis of the performance test results, we find that with the increase of Si C body fractions, the thermal conductivity, the thermal expansion, the bending strength, the density and the shear strength of interface all decrease. With the increase of Si C particle sizes, the thermal expansion, bending strength and density decrease, but the thermal conductivity increases. With the increase of billet heating temperature, the thermal conductivity and thermal expansion coefficient are reduced, the bending strength of 50 vol.% box part is improved, while the bending strength of 55 vol.% and 60 vol.% are reduced. With the increase of the billet holding time, the bending strength increases first and then decreases. With the increase of molding pressure, the bending strength gets improved.After a comprehensive comparison of the performance and the joining effect of the box part, it can be concluded that with the billet holding at 640 ℃ for 8min and forming by the pressure of 987 MPa, the effect of forging and joining is the best. Under the same condition, the 55 vol.%-14μm Si Cp/Al-6061 Al box part can achieve good performance, with the density of 98.7%, the thermal conductivity of 144 W/(m·k), the thermal expansion of 9.09×10-6·K-1, the bending strength of 627 MPa, and the shear strength of interface of 181 MPa.