New Systems Development And Fluidity Research Of Low Melting Points Gallium-based Liquid Metals

Gallium based liquid metals,which have the characteristics of both metals and liquids at room temperature,show unparalleled advantages in the fields of flexible circuits,microfluidics,thermal managements,syntheses and catalyses of new materials,and have broad prospects.As a new type of material,it has been widely concerned and studied at home and abroad in recent years.However,new materials mean new challenges,and gallium-based liquids metals are inevitably restricted by some technical barriers.Among them,how to lower the melting points has become a basic and extremely important issue.In this paper,by foucing on the melting points and viscosity of gallium based liquid metals,the following works have been carried out.The domestic and foreign reports concerning the compositions and melting points of gallium-based liquid metals have been verified.At present,researches on gallium-based liquid metals are not in-depth enough,and relatively few basic researches have led to very big differences in reports on the melting points of gallium-based liquid metals.In this thesis,a differential scanning calorimeter was used to test the melting points of gallium-based liquid metals.On one hand,the reported melting points of gallium-based liquid metals was checked,and on other hand,it also offers new results for the melting points of gallium-based liquid metals.The influences of single element micro-addition on the melting points of gallium-based liquid metals were explored.Based on the phase diagram and heat of mixing,this dissertation sorts out specific elements that can form a good eutectic with gallium-based liquid metals(such as Ga,In,Sn,Zn,etc.)with non-negative heat of mixing.such as Al and Cd.According to the idea of alloying,they were added respectively into eutectic GaInSnZn in small amounts,and the melting points of the gallium-based liquid metals were reduced to below 7 ?.Then,the influences of adding intermetallic compounds and elements with non-metallic properties on the melting point of the eutectic GaInSnZn were also explored.Multi-elements minor-addition on the melting points of gallium-based liquid metals were further explored.In this thesis,Mg was introduced on the basis of Al and Cd to develop a five-to-seven-membered gallium-based liquid metals system,which reduced the melting points from about 7 ? to 6.07 ?.Then,based on the idea of adding Al+X and Cd+Y to gallium-based liquid metals,an eighth element,such as Si,was developed,which lowered the melting points of gallium-based liquid metals to 5.88°C.The viscosity of gallium-based liquid metals was measured at different temperatures by capillary method.It was found that under the same temperature,the viscosity of galliumbased liquid metals increased with the increase of components.From pure gallium to GaInSnZn,the viscosity increase is about 0.4 m Pa ·s.