Microstructure and thermal properties of Mo-coated graphite fiber/Cu composites

Mo-coated graphite fiber/Cu composites were fabricated by vacuum hot-press sintering with milled mesophase pitch-based graphite fibers and Cu powder.The molybdenum coatings on the fibers were obtained via metal organic chemical vapor deposition technique.Microstructure and thermal properties of the composites was examined.The results show that the fibers have a preferential orientation in the plane perpendicular to the pressure axis,which leads to the composites possess higher thermal conductivities and lower coefficients of thermal expansion(CTEs) at the 2-D direction.The Mo coating reacts with graphite fiber,and part of which forms a continuous Mo2C layer during densification process,which can improve the interfacial bonding between the fiber and metal matrices effectively,and then improve the thermal properties of the composites.The composites achieve 2-D thermal conductivities between 367 382 W/(m.K) and CTEs of 4.2×10 6 8.6×10 6 K 1 with the fiber content ranging 35% 55%(volume fraction).They can commendably meet the heat dispersion and matching requirements of power electronic devices to the packaging materials.