Fabrication of multi-functional gallium-based liquid metal composites and their applications

Abstract

This dissertation contains the contents of the fabrication and the application of various multifunctional composite materials including high heat dissipation materials and hydrogen production materials using gallium-based liquid metal. Liquid metal refers to a metal which is liquid at or near room temperature. Among various liquid metals, unlike mercury, gallium-based liquid metals with low toxicity have been actively studied for the past 10 years. Utilizing the electrical and thermal conductivity of liquid metal, it has been widely used as an electronical circuits or heat dissipation materials for various soft robotics or flexible devices. However, the heat dissipation material had a limited processing method such as dispersing a low content of liquid metal, and accordingly, the thermal conductivity of the liquid metal composite was much lower than that of the liquid metal. In this dissertation, a 3D printable heat dissipation material was fabricated by increasing the liquid metal filler to achieve high thermal conductivity and controlling the rheological properties at the high filler fraction. In addition, by using liquid metal as a filler, the trade-off relation of thermal conductivity and processability of conventional heat dissipating materials was overcome, and high thermal conductivity and excellent processability were achieved at the same time. Furthermore, the actual heat dissipation rate was observed through an IR camera and quantified by comparing it with simulation. More recently, research has been conducted to utilize liquid metals as catalysts in various reactions including hydrogen production and photocatalysis. However, the related research has not been conducted enough to be expressed as an incubation state, and the mechanism has not yet been elucidated. Therefore, in this dissertation, an aluminum-liquid metal composite material was fabricated, used for hydrogen production, and the mechanism was observed. In addition, based on the observation, the structure was designed and fabricated to increase the yield of hydrogen production.