| Owing to the miniaturization,high integration and high power density of electronic components,their heat generation has increased dramatically,and thermal management of electronic devices has become particularly important.High-performance thermal management materials can effectively help the heat dissipation of electronic components,which is the basis of thermal management of electronic devices.Thermal management materials are divided into passive thermal management materials(thermal interface materials,heat sinks,heat sinks,substrates,etc.)and active thermal management materials(thermoelectric materials).Because of its excellent thermal conductivity and filling properties,thermal grease can be used as a thermal interface material and is one of the important materials for the thermal management of electronic devices.In addition,in terms of thermoelectric materials,silver telluride nanowires(Ag2Te NWs)are the most potential raw materials for the preparation of flexible thermoelectric materials because of their excellent thermoelectric properties.Although there has been some progress in the research of thermal grease and flexible thermoelectric materials,it is still insufficient to meet the heat dissipation requirements of electronic devices.In this dissertation,hydrogenated silicone oil and dimethyl silicone oil are used as the matrix,and aluminum oxide(Al2O3),silver(Ag),aluminum(Al)and zinc oxide(ZnO)are used as fillers to prepare thermal grease;Ag2Te NWs welded at room temperature were used to prepare flexible thermoelectric films.The specific research contents and conclusions are as follows:(1)Using Al2O3,ZnO,Ag and Al as fillers,decyltrimethoxysiloxane as surface modifier,hydrogen-containing silicone oil and dimethyl silicone oil as substrates,thermal grease was prepared,analyzed and characterized.It was found that large particles of Ag are better dispersed in thermal grease than small particles of Ag to form thermally conductive pathways;because Ag has high thermal conductivity,the thermal conductivity of thermally conductive silicone grease can increase by more than 3%for every 1.5%increase in the amount of Ag added;Ag's good conductivity will make the thermal grease more easily penetrated by electricity,and its breakdown strength is 2.547 kV/cm;because decyltrimethoxysiloxane can react with the hydroxyl groups on the surface of Al,the Al spheres can be better dispersed in silicone oil;spherical Al can further improve the thermal conductivity of thermal grease.With the same filler content,its thermal conductivity can be increased by 63.6%(from 3.3 W/mK to 5.4 W/mK),and the introduction of large particles of Al spheres can significantly reduce the viscosity of thermal grease,which is conducive to us to further improve the thermal conductivity of the sample.(2)Ag2Te NWs flexible thermoelectric film welded at room temperature was prepared by simple vacuum filtration and drip coating method and its related properties were characterized.It was found that due to the welding of nanowires,the conductivity of the thermoelectric film could reach 15335.05 S/m and the power factor was 151.76 ?Wm-1K-2;the thermoelectric performance of the film reached value of 359.76 ?Wm-1K-2 at 420 K.Due to the welding of nanowires and the existence of a dense network structure of the film,the film resistance has only become 1.3 times the initial resistance after 1,000 cycles of bending.In the finger touch test,the film can stably output a voltage of about 0.52 mV when the finger is touched,and has a relatively fast response speed.In the thermoelectric module output current-voltage curve test,due to the high Seebeck coefficient and conductivity of the film,the module can output a voltage of nearly 4 mV under a temperature difference of 40 K,which indicates that the prepared Ag2Te NWs flexible thermoelectric film welded at temperature has good thermoelectric performance.It shows that the room-temperature welded Ag2Te film has great potential to be used in the field of thermoelectric refrigeration. |
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