Study On Microstructure And Properties Of Graphite Film/Aluminium Composites

In this work, TGS-25/Al, TGS-25/Al-12 Si and TGS-25/Al-20 Si composites were fabricated by squezzing casting method. The effect of Si content on the microstructure, thermal properties and mechanical properties of Gf/Al composites is analyzed.The high crystallinity graphite film has the smoothness surface and order layer-shaped structure. The thermal conductivity of graphite film is related to the degree of ordering, graphitization degree, microcrystalline stack height and the layered structure. if the graphite film have higher degree of graphitization, bigger height of microcrystalline stack and more intergrated graphite plane, the graphite film have higher thermal conductivity along the film. And different raw materials and preparation process of graphite film, should analysis the microcrystalline stack height with the microstructure analysis, to determine the thermal conductivity. TGS-25 graphite film has a uniform directional layer structure, interlayer combination closely. The graphite films’ degree of graphitization degree is 99.9% and thermal conductivity along the direction of film is 1420 W/(m·K).Graphite film reinforced aluminium composites don’t have the obvious defects, such as porosity and crack, and the matrix and reinforcement have evenly distributed. With the increase of mass fraction of Si in the matrix alloy, C elements in matrix alloy, the mass fraction and diffusion depth is relatively lower.With the reduce of mass fraction of Si in the matrix alloy, the composite thermal conductivity is reduced, along the film direction thermal conductivity increased from 420W/(m·K) to 743W/(m·K), Perpendicular the film direction thermal conductivity increased from 11W/(m·K) to 17W/(m·K). The thermal conductivity of the composite mechanism conforms to Agari model, with the increase of mass fraction of Si in the matrix alloy, the difference between the theoretical value of thermal conductivity of composite and the actual value, increased gradually.With the increase of mass fraction of Si in the matrix alloy, the average thermal expansion coefficient of composite is reduced. Between 0℃ and 400℃, TGS-25/Al composites’ average thermal expansion coefficient is the maximum, the range of 22.5~24.4×10-6K-1. TGS-25/Al-20 Si composites’ average thermal expansion coefficient is the minimum, the range of 16.8~19.3×10-6K-1.With the increase of Si content, the composites’ Inerlaminar shear strength is increased. TGS-25/Al composites’ mean value of interlaminar shear strength is 55.6MPa; TGS-25/Al-20 Si composites’ mean value of interlaminar shear strength is 103.9MPa. TGS-25/Al–20Si composites’ interlaminar shear strength is 1.87 times more than TGS-25/Al composites’ interlaminar shear strength.