先驱体转化致密碳化硅纳米复合材料的制备及其热电性能

Preparation and thermoelectric properties of polymer-derived dense Si C nanocomposites

以聚碳硅烷和锑改性聚硅烷为先驱体，利用先驱体转化SiC材料的富余自由碳高温石墨化的微观结构演变特点，采用热压烧结、先驱体浸渍－裂解法以及退火工艺制备出先驱体转化SiC纳米复合材料。采用SEM、TEM、XRD和Raman等测试手段表征和分析了相组成和微观结构，讨论了样品的热导率、电导率和塞贝克系数等热电参数随温度变化关系。研究表明，所得致密SiC纳米复合材料为n型热电材料。由于纳米石墨的作用，材料热导率抑制在4～8W／（m＆#183;K）范围。1600℃退火处理能够降低热导率，同时提高电导率和塞贝克系数绝对值，使先驱体转化法得到的SiC纳米复合材料无量纲热电优值ZT达到0．0028（650℃），高于其他已报道的致密SiC／C复合材料和纳米复合材料体系。

Taking polycarbosilane and antimony-modified polysilane for precursors and drawing lessons from the transformation process of high temperature graphitization of spare free carbon in SiC materials,the polymer-derived SiC nanocomposites were prepared by employing hot-press sintering,precursor infiltrating-cracking methods and annealing.The phases and microstructures were characterized and analyzed by using SEM, TEM,XRD and Raman test methods.The thermoelectric parameters of samples,such as thermal conductivity,electrical conductivity and Seebeck coefficient,were studied.Results show that the dense SiC nanocomposites acquired are n-type thermoelectric materials.The thermal conductivity is suppressed at the range of 4~8W/（m＆#183;K）due to the function of nano-graphite.At the annealing temperature of 1600＆#176;C,the thermal conductivity reduces while both the electrical conductivity and the Seebeck coefficient increase,and ZT value of SiC nanocomposites derived from precursor reaches to 0.0028（650＆#176;C）,which is higher than that of SiC/C composites or nanocomposites ever reported.