Lightweight and highly thermally conductive Ga-based liquid metal hybrid composites filled with hollow glass microspheres

In this study, glass bubbles (GBs) and gallium-based liquid metal (LM) were combined at varying volume fraction ratios to prepare the composites (GB-LMs), with the objective of optimising their state of matter and overall properties. Furthermore, the incorporation of high thermal conductive particles, including copper and silver, was pursued in augmenting the thermal conductive efficiency of the resulting composites. The thermal conductivity (TC), electrical conductivity (EC) and density were measured in order to construct a comprehensive structure - property relationship, while the underlying microphysical mechanisms were elucidated through the numerical simulations based on the distinctive architectures observed. As the loading of LM droplets increases, the GB-LMs undergo a transition from a scattered state to a thick pasty state and then to a dilute gel state. The composite sample with a loading of 32 % LM droplets exhibited a moderate pasty state, with a TC of 4.7 W/(m·K), an EC of 380 S/m, and a density of 2.4 g/cm 3 . The introduction of copper or silver powders into the GB-LMs resulted in a TC of 8.0 W/(m·K), an EC of 1.59 × 10 4  S/m and a low density of 3.2 g/cm 3 . The incorporation of high TC particles into GB-LMs has the potential to markedly improve the TC-to-density ratio of the composite system. These findings facilitate the implementation of LM-based composites in the advanced thermal management.