镓基液体金属在不同介质表面的润湿性研究

Wettability of Gallium-Based Liquid Metals on Different Media Surfaces

以Ga66In20Sn10Bi3.5Zn0.5(质量分数)五元镓基液体金属为基础,用综合热分析仪、导热系数测试仪以及高温电镜研究了其基本物理性能和在常用散热组元材料表面上的润湿行为,研究结果表明该镓基液体金属的熔点为3.1℃,20℃时的密度为6.67 g·cm^(-3)、导热系数为21.5W·m^(-1)·℃^(-1)、比热容为504 J·kg^(-1)·℃^(-1)、导电率为3.46×106S·m^(-1),相对于纯镓和镓铟锡合金其热导特性明显提高。在3.1~100℃的温度范围内,该镓基液体金属在聚氯乙烯塑料(PVC)、硅、铜合金、铝合金等基体表面的润湿性是依次提高的,即PVC<硅<铜合金<铝合金,随着温度升高接触角随之降低,分别从3.1℃的147°,133°,135°,131°降低到100℃时的107°,62°,45°,37°,分别减小了40°,61°,90°,94°。在所研究的温区内,不同温度下得到的接触角数据能够很好地展现接触角随温度的变化情况,同时也展示了液态镓独特的润湿特性。结果表明该五元镓基液体金属可以与常规散热器件组元材料匹配良好,可实现大功率、高热量器件的快速散热。

In recent years,with the rapid development of science and technology,there were more and more serious heat dissipation problems of high-power and high-heat-flow devices in many industries.The first and foremost was the field of electronics,information and optoelectronic technology.At present,the liquid metal thermal conductive materials were considered as one of the best high performance heat dissipation materials in the future because of their high heat conduction rate,large heat absorption capacity,high heat transfer capacity and stable and controllable physical chemistry properties.In recent years,many researchers had studied low-meltingpoint gallium-based liquid metal from the research of material preparation,performance and application,and obtained many valuable research results.But the wettability of liquid metal on the surface of different media was not involved,and the wettability of liquid metal would determine the structure,the heat dissipation efficiency and the overall efficiency of the radiator.Therefore,the wetting behavior of five-element gallium-based liquid metal(such as copper alloy,aluminum alloy,silicon,polyvinyl chloride(PVC),etc.)on the surface of common heat dissipation materials was involved.The wettability of gallium-based liquid metal on different surfaces was analyzed,and the flow and heat transfer characteristics of gallium-based liquid metal in these channels were evaluated here.On the basis of GaInSn ternary alloy,zinc and bismuth were introduced to further reduce the melting point of the alloy to obtain the system of GaInSnBiZn five-element alloy with specific compositions such as Ga66In20Sn10Bi3.5Zn0.5(mass fraction).The raw materials were indium 99.96%,gallium 99.999%,tin 99.996%and bismuth 99.95%,zinc 99.99%.Gallium was first heated by an alcohol lamp in a nickel crucible in argon atmosphere to melt it at temperature of 200~250℃,then indium,tin,bismuth and zinc were added in turn and stirred with a glass rod until the alloy was completely dissolved,the gallium-based liquid metal was obtained by soaking at 200-250℃for 10 min.The specific heat capacity(Cp)and melting point(Tm)of liquid gallium were measured with a comprehensive thermal analyzer(STA449C,Nietzsche,Germany).The specific heat capacity(dH/dT)and differential scanning calorimetry(DSC)curves of gallium-based liquid metal(10-20 mg)were obtained in an open argon atmosphere from^(-1)0 to 200℃at 10℃·min^(-1),to get Cp,Tm,respectively.The conductivity of liquid gallium was measured by conductivity Tester(EC-4110,Kuosi,Shanghai).The thermal conductivity of liquid gallium was measured by the DRL-ii(Xiangtan Instrument,Hunan).The physical morphology of gallium-based liquid metal with 5 mm square on different carriers was observed by high temperature electron microscope(RDS-04,Northeastern University,China)from-30 to 100℃,the temperature dependence of the wetting angle between liquid metal and carrier surface was observed.Based on Ga66In20Sn10Bi3.5Zn0.5 five-element gallium liquid metal,the wetting behavior on the surface of common heat dissipation materials was studied,the wettability of liquid gallium metal on different surfaces was analyzed.The results were as follows:the melting point of Ga66In20Sn10Bi3.5Zn0.5 five-element liquid gallium metal was 3.1℃,the density was 6.67 g·cm^(-3),the thermal conductivity was 21.5 W·m^(-1)·℃^(-1),the specific heat capacity was 504 J·kg^(-1)·K^(-1),the conductivity was 3.46×106 S·m^(-1),and the thermal conductivity was significantly higher than that of pure gallium and indium tin alloys.The contact angle of Ga66In20Sn10Bi3.5Zn0.5 liquid gallium on the substrates of PVC,silicon,copper alloy and aluminum alloy decreased with the increase of temperature from 147°,133°,135°and 131°at 3.1℃to 107°,62°,45°and 37°at 100℃with the reduction of 40°,61°,90°and 94°,respectively.Compared with pure gallium and gallium indium tin alloy,the thermal conductivity of the gallium alloy was obviously improved.In the temperature range of 3.1~100℃,the wettability of the gallium base liquid metal on the matrix surface of polyvinyl chloride(PVC),silicon,copper alloy,aluminum alloy,was increased in turn with the order of PVC<silicon alloy<copper alloy<:aluminum alloy,and with the rising of temperature.In the temperature range of this study,the contact angle data obtained at different temperatures could show the change of contact angle with temperature well and also showed the unique wetting characteristics of liquid gallium.From the analysis results,it could be seen that the gallium base liquid metal could match the conventional heat dissipation device component material well,and could dissipate the heats quickly for the high probability and high energy devices.