摘 要
 
SiO2氣凝膠是一類輕質(zhì)介孔材料，具有超低密度、高孔隙率、高比表面積和低熱導(dǎo)率等特點(diǎn)，在許多領(lǐng)域具有潛在的應(yīng)用前景。目前國內(nèi)外多以正硅酸甲酯、正硅酸乙酯為硅源、以超臨界干燥工藝制備SiO2氣凝膠，其制備工藝過程復(fù)雜，耗能費(fèi)時，成本昂貴，原料有一定的毒性，超臨界高溫高壓干燥存在較大的危險性。而SiO2氣凝膠常壓干燥制備技術(shù)研究較少，且制備出SiO2氣凝膠性絕熱能與超臨界干燥法相比較差。同時未改性的SiO2氣凝膠親水疏油。這些問題限制了SiO2氣凝膠材料的發(fā)展與應(yīng)用。
本論文研究以水玻璃為硅源，常壓干燥制備低密度、高性能的介孔SiO2氣凝膠材料，試驗(yàn)研究了：凝膠體系pH、甲酰胺的添加、濕凝膠的老化、表面疏水處理以及常壓低溫干燥工藝對氣凝膠制備過程及所制備氣凝膠的自然密度、振實(shí)密度、孔徑大小和比表面積等指標(biāo)的影響。試驗(yàn)結(jié)果表明：當(dāng)體系pH為5時，所得氣凝膠的性能最佳；當(dāng)甲酰胺的添加量為1.5ml時，孔徑大小分布范圍大都在10nm左右，比表面積為610.6m2/g；當(dāng)用30%的正硅酸乙酯/乙醇溶液對濕凝膠進(jìn)行老化處理時，能夠得到塊狀、高比表面積的二氧化硅氣凝膠材料；利用三甲基氯硅烷和正己烷的混合溶液對濕凝膠進(jìn)行表面疏水修飾處理，TMCS與孔洞中水的摩爾比為0.35時，所得氣凝膠的疏水度為43.95%；選用正己烷做為溶劑替換介質(zhì)，干燥工藝為50℃84h，60℃72h時，所得氣凝膠的密度為0.14g/cm3，孔隙率為93.7%，比表面積為610.643m2/g，孔直徑為9.72nm。

關(guān)鍵詞：SiO2氣凝膠，水玻璃，制備工藝，性能

Abstract

Silica aerogels are a class of light mesoporous materials with low density, high porosity,high surface area and low thermal conductivity. Because of their unique properties, silica aerogels have great potential application future in many fields. Currently, with the technology of supercritical drying , silica aerogels was made of TMOS and TEOS in domesitc and abroad. Because the process of the made tehchnology was very complex, time-consuming,inefficient and costly, and the raw was toxic, and the technology of supercritical drying was dangerous, however, the technology of drying under the normal altmospheric pressure was still lack, the structure of the property of silica aerogels was not compared with that by using the technology of supercritical drying, meanwhile, unmodified silica aerogels was hydrophilic,which limited the current industrial application of silica aerogels materials.
The thesis studied the mesoporous material of silica aerogels with low denisty and high performance which source was low-cost water glass and that was made by the technology of drying under the normal altmospheric pressure. The expriment studied the influence of indicators, it contained gelling system pH, the addition of formamide, wet gel aging, surface hydrophobic treatment ,the process of mading aerogel structure by the technology of drying under the normal altmospheric pressure and aerogel structure’s natural denisty, tap density, aperture size and specific surface area. The results showed that when the system pH is 5, the performance of the obtained Aerogel was topgallant； When the addtion of formamide was 1.5ml, BJH pore size distribution was mostly in 10nm, and the specific surface area was 610.6m2/ g; With 30%vol.of TEOS/ethanol solution of the wet gel aging treatment, massive and high specific surface area of silica aerogels materials can be obtained; using Chlorotrimethylsilane and n-hexane on the wet surface modification hydrophobic treatment, When TMCS and n-hexane molar ratio was 0.35, the degree of hydrophobic of obtained aerogels was 43.95%. using n-hexane as solvent medium, drying process to 50 ℃ 84h, 60 ℃ 72h, the density of aerogels obtained 0.14g/cm3, porosity was 93.7%, specific surface area 610.643m2/g, pore diameter 9.72nm.

KEY WORDS: silica aerogel, water glass, preparation technology，performance

目  錄
第一章  緒論 1
1.1 前言 1
1.2 氣凝膠絕熱材料發(fā)展及研究現(xiàn)狀 2
1.2.1 國外研究現(xiàn)狀 2
1.2.2 國內(nèi)研究現(xiàn)狀 3
1.3 論文研究目的意義及研究內(nèi)容 3
1.3.1 論文研究的目的和意義 3
1.3.2 論文研究的主要內(nèi)容 4
第二章  實(shí)驗(yàn)部分 5
2.1 實(shí)驗(yàn)材料及實(shí)驗(yàn)設(shè)備 5
2.1.1 實(shí)驗(yàn)材料 5
2.1.2 實(shí)驗(yàn)設(shè)備 5
2.2 實(shí)驗(yàn)方案 6
2.2.1 SiO2氣凝膠制備工藝 6
2.2.2 凝膠工藝參數(shù)影響試驗(yàn) 7
2.2.3 老化工藝試驗(yàn) 7
2.2.4表面修飾試驗(yàn) 7
2.2.5 化學(xué)干燥劑添加量試驗(yàn) 8
2.2.6 干燥工藝試驗(yàn) 8
2.2.7檢測方法 8
第三章  結(jié)果分析與討論 9
3.1 pH值對氣凝膠密度、凝膠時間及微觀結(jié)構(gòu)的影響 9
3.2 老化工藝對氣凝膠性能的影響 11
3.3 表面修飾對氣凝膠性能的影響 12
3.4 DCCA添加量對氣凝膠性能的影響 14
3.5 常壓低溫干燥工藝對氣凝膠性能的影響 17
結(jié)論 19
參考文獻(xiàn) 21