發(fā)布時間：2018-05-16 06:46

  本文選題：納米孔 + 氣凝膠��； 參考：《遼寧科技大學》2015年碩士論文

【摘要】：化石能源的日益枯竭及其在使用過程中引發(fā)的環(huán)境污染正在迫使人們越來越傾向于合理高效地利用有限的自然資源,隔熱技術(shù)就是實現(xiàn)資源高效利用的重要手段。近年來,納米技術(shù)不斷進步,所獲材料的應(yīng)用領(lǐng)域也在不斷拓新。納米多孔材料的孔隙處于納米尺度,因此表現(xiàn)出優(yōu)異的熱絕緣性能,是高性能隔熱材料領(lǐng)域的研究熱點。本文首先考察了基于超臨界干燥工藝和一種非超臨界干燥工藝合成的SiO2氣凝膠的主要性質(zhì),對比了兩種工藝條件下所獲氣凝膠材料的多孔網(wǎng)絡(luò)結(jié)構(gòu),及其對于材料熱隔離能力的影響。然后按照經(jīng)典的合成路線分別制備了具有二維六方結(jié)構(gòu)相的SBA-15,MCM-41以及具有三維體心立方結(jié)構(gòu)的SBA-16介孔分子篩材料,對以上分子篩材料的晶體結(jié)構(gòu)、微觀形貌以及孔結(jié)構(gòu)參數(shù)進行了表征,著重考查它們的隔熱性能,為拓展納米多孔性質(zhì)分子篩材料的應(yīng)用領(lǐng)域提供一定可參考的實驗數(shù)據(jù)。最后,采用有限元分析方法對鋼包溫度場進行數(shù)值模擬,分析了納米多孔保溫隔熱層對鋼液溫度和包襯傳熱情形的影響。通過以上各方面的研究,獲得的主要研究結(jié)果如下:(1)盡管共沸蒸餾干燥工藝可使氣凝膠顆粒表面產(chǎn)生疏水效應(yīng),所獲氣凝膠材料與超臨界干燥工藝獲得的氣凝膠材料同屬非晶態(tài),且兩者的氮氣吸附曲線也表明均屬于IV型,但是前者歸屬于典型的H2類型,整體表現(xiàn)為不完好的介孔特性;而后者則更傾向于H1型,說明通過超臨界干燥的氣凝膠內(nèi)部的介孔孔徑較為均勻統(tǒng)一,其集中分布在2~40nm范圍內(nèi)。納米孔隙微觀結(jié)構(gòu)上的差異導(dǎo)致后者具有較低的導(dǎo)熱系數(shù),常溫下和200℃時分別僅為0.020/0.033 W·m-1·K-1。(2)SBA-15分子篩呈長1μm、寬0.5μm且粒徑均勻的短棒狀,其內(nèi)部介孔孔道具有很高的一級定向和較為規(guī)則二級取向定向。MCM-41分子篩則為不規(guī)整的短棒狀和顆粒狀,而采用EISA路線合成的SBA-16分子篩呈粒度約為1μm的“單晶”多面體狀,表現(xiàn)出僅在介觀尺度上有序。氮氣吸附測試表明,二維六方結(jié)構(gòu)相的SBA-15和MCM-41分子篩由BJH模型計算得到的孔徑分別集中分布在8~12nm之間和2~4nm之間,以SBA-16分子篩為代表的三維體心立方結(jié)構(gòu)介孔材料的孔道窗口只有約4nm,三種材料的平均孔徑依次為7.47、3.53和5.29nm。其中,MCM-41分子篩具有最低的常溫導(dǎo)熱系數(shù),僅為0.043 W·m-1·K-1。(3)將10mm厚的納米多孔隔熱材料用作鋼包保溫層,相比于無保溫層和采用常規(guī)隔熱材料作為保溫層的鋼包,在鋼水靜置15min后,可使鋼水溫度分別提高6.82℃和3.12℃,將鋼水的溫降速率降低至0.1938℃·min-1,同時將鋼殼外壁溫度降低了約113℃。
[Abstract]:The depletion of fossil energy and the environmental pollution caused by the use of fossil energy are forcing people to make more and more rational and efficient use of limited natural resources. Thermal insulation technology is an important means to achieve efficient use of resources. In recent years, nanotechnology continues to progress, the application of materials are also constantly expanding. The pores of nano-porous materials are in nanometer scale, so they exhibit excellent thermal insulation performance and are the research hotspot in the field of high performance thermal insulation materials. In this paper, the main properties of SiO2 aerogels based on supercritical drying process and a non-supercritical drying process are investigated, and the porous network structure of aerogel materials obtained under two conditions is compared. And its influence on thermal isolation ability of materials. Then, SBA-15MCM-41 with two-dimensional hexagonal structure and SBA-16 mesoporous molecular sieve with three-dimensional body-centered cubic structure were prepared according to the classical synthesis route. The microstructure and pore structure parameters were characterized with emphasis on their thermal insulation properties. The experimental data can be used to expand the application field of nano-porous molecular sieve materials. Finally, the finite element method is used to simulate the temperature field of ladle, and the influence of nano-porous thermal insulation layer on the temperature of liquid steel and the heat transfer of ladle lining is analyzed. The main results obtained from the above studies are as follows: 1) although azeotropic distillation and drying process can cause hydrophobic effect on aerogel particle surface, The aerogel materials obtained by supercritical drying process belong to amorphous state, and their nitrogen adsorption curves also show that they belong to type IV, but the former belongs to the typical H2 type, and the whole aerogel material exhibits imperfect mesoporous properties. The latter is more inclined to H1, indicating that the mesoporous pore size of the aerogel by supercritical drying is uniform and concentrated in the range of 2~40nm. The difference in the microstructure of the nano-pore leads to the lower thermal conductivity of the latter, which is only 0.020 / 0.033 W / m ~ (-1) K-1.(2)SBA-15 molecular sieve at room temperature and 200 鈩，

本文編號：1895872