石墨纳米片的改性及电热特性的研究

发布时间：2018-05-28 16:28

  本文选题：电热特性 + 石墨纳米片　； 参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：石墨烯产品的科学研究以及工程应用成为科技工作者以及工程技术人员努力开发的热点。而石墨烯电热制品,是最接近市场应用的一类产品,因此开展本文工作,势在必行。电热材料是通过焦耳效应将电能转化为热能的材料,目前主要使用的电热材料是由重金属合金制成的电阻丝。但金属电热材料存在重量大,不耐腐蚀,冶炼污染严重等缺点,需要找到一种新的电热材料来替代它。石墨纳米片(GNS)不仅导电能力非常优良,环境友好,而且具有价格低廉,热转换效率高的优点;另外,石墨制品电热红外特性还具有保健理疗的特殊效果,非常适合替代金属成为新的电热材料。但石墨纳米片在水溶液中易团聚,不利于加工,需要对它进行一定程度的改性。本文以石墨纳米片为原料制作一种电热薄膜,分析这种电热膜的各项性能,并尝试对纳米片进行一定的改性,研究改性对薄膜的影响,最后对产生影响的原理进行了探讨。以膨胀石墨为原料,通过超声剥离的方法制备石墨纳米片。将这种石墨纳米片作为导电填料,硅酸钠溶液做为成膜基质,使用凹版印刷法制备了一种无机电热膜。对这种电热膜进行分析,发现其具有非常高的发热效率和电导率,在无机材料的表面附着力非常强,加速寿命试验证明它有超过20万个小时(22年)的使用寿命。进一步研究发现,薄膜的电导率与纳米片的添加量成正比,这一结果与渗流阈值模型的预测相符合;薄膜的尺寸与纳米片的大小也对导电能力有影响,其实质是影响石墨纳米片之间相互接触的概率。使用硫酸氧钛作为钛源,利用水热法对石墨纳米片进行改性,并研究了水热的温度、预氧化和分散剂对改性的影响。分析测试结果表明,石墨纳米片的表面生成了一层由大量二氧化钛小颗粒组成的薄膜,并于石墨纳米片之间存在化学键上的联系。水热温度在140℃下有最好的结果,预氧化能增多二氧化钛附着的位点,生成了大量的直径50nm以上的大颗粒;六偏磷酸钠对改性有着较强的促进作用,可以使改性产物有着更大的比表面积。将改性后的纳米片制成电热膜,与未改性的薄膜对比发现,改性后制作的薄膜电阻由34Ω下降至19Ω,并有着更高的使用温度。结合对改性纳米片的分析,发现电导率的提升是三种因素的共同作用:二氧化钛颗粒阻止纳米片堆叠,纳米片由疏水变为亲水以及硅酸钠对二氧化钛的分散作用。
[Abstract]:The scientific research and engineering application of graphene products have become the focus of scientific and technical researchers and engineers. The graphene electrothermal products are the most close to the market application, so it is imperative to carry out the work in this paper. Electrothermal material is a kind of material which converts electric energy into heat energy by Joule effect. At present, the main electrothermal material used is resistance wire made of heavy metal alloy. However, metal electrothermal materials have many disadvantages, such as heavy weight, low corrosion resistance, serious smelting pollution and so on, so it is necessary to find a new electrothermal material to replace it. The graphite nanochip GNS not only has excellent electrical conductivity, friendly environment, but also has the advantages of low price and high efficiency of heat conversion. In addition, the electrothermal infrared characteristic of graphite products also has the special effect of health therapy. It is very suitable to replace metal as a new electrothermal material. However, graphite nanoparticles are easy to agglomerate in aqueous solution, which is not conducive to processing, so it needs to be modified to some extent. In this paper, a kind of electrothermal film was made from graphite nanosheet. The properties of the film were analyzed, and the influence of the modification on the film was studied. Finally, the principle of the influence was discussed. Graphite nanoparticles were prepared by ultrasonic stripping from expanded graphite. A kind of inorganic electrothermal film was prepared by gravure printing using the graphite nanochip as conductive filler and sodium silicate solution as film forming matrix. It is found that the electrothermal film has a very high heating efficiency and conductivity and strong adhesion on the surface of inorganic materials. The accelerated life test shows that it has a service life of more than 200,000 hours (22 years). Furthermore, it is found that the conductivity of the films is proportional to the amount of nanocrystalline films, which coincides with the prediction of the percolation threshold model, and the size of the films also have an effect on the conductivity. Its essence is to influence the probability of contact between graphite nanoparticles. Graphite nanoparticles were modified by hydrothermal method using titanium sulfate as titanium source, and the effects of hydrothermal temperature, preoxidation and dispersant on the modification were studied. The results show that a thin film composed of a large number of titanium dioxide particles is formed on the surface of graphite nanocrystalline and there is a chemical bond relationship between graphite nanocrystals. Hydrothermal temperature at 140 鈩，

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