High thermal conductivity in diamond induced carbon fiber-liquid metal mixtures

Gallium (Ga)-based liquid metal (LM) paste is deemed to have potential and extensive applications in the thermal management of electronics. However, some non-metallic carbon-based materials such as diamond or carbon fiber (CF) cannot be wetted by Ga, which is difficult to prepare composites using manual stirring without surface modification. Here, the repeated compression method of the forced wetting was successfully used to prepare the Ga-based LM composites containing carbon-based materials without surface modification. New oxide skin of LM will generate during repeating compression. The bonding mechanism between diamond (/CF) and Ga is that Ga oxide is attached to the diamond (/CF) and then being wetted and coated by Ga. Diamond and CF can be separated and recycled from Ga-based paste. A high thermal conductivity value of 129 W m-1 K-1 was obtained by inducing the distribution of CF using diamond particles, in which liquid Ga was the connecting phase. The density of Ga can be reduced by 21% and the thermal conductivity of the Ga-based paste over 100 W m-1 K-1 can be maintained. The successful development of the Ga-based LM/diamond/CF composite indicates that excellent thermal conductivity can be achieved by inducing the distribution of anisotropic particles using isotropic particles.