發(fā)布時間：2018-02-27 10:14

  本文關(guān)鍵詞： 氧化鋁氣凝膠 凹凸棒土(ATP) 強度　出處：《東南大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：氧化鋁氣凝膠除具有一般氣凝膠的基本性質(zhì),還具有優(yōu)異的高溫穩(wěn)定性,是制備耐高溫隔熱材料的理想材料。但目前報導(dǎo)得到的氧化鋁氣凝膠材料普遍存在強度低、力學(xué)性能差的缺點,這嚴(yán)重制約了其實際應(yīng)用。凹凸棒土(ATP)是種具有獨特的層鏈狀晶體結(jié)構(gòu)的含水富鎂鋁硅酸鹽粘土礦物,具有優(yōu)異的吸附性、填充性及熱穩(wěn)定性等。鑒于其獨特的結(jié)構(gòu)和穩(wěn)定的物理化學(xué)性質(zhì),本文采用凹凸棒土作為增強體,常壓直接干燥制備高強度氧化鋁氣凝膠。首先,實驗從水(H2O)和乙醇(EtOH)用量比例、環(huán)氧丙烷(PO)用量以及ATP加入方式幾個方面優(yōu)化了實驗工藝。通過觀察和借助相關(guān)表征,最終確定H2O:EtOH=3:7vol,環(huán)氧丙烷用量為n(Al):n(PO)=1:8,ATP添加方式為制備成穩(wěn)定的ATP懸浮液后再添加到氧化鋁溶膠,效果最佳。其次,研究了ATP用量對A1203氣凝膠復(fù)合材料力學(xué)等性能的影響。研究結(jié)果表明：加入ATP后,氣凝膠復(fù)合材料的表觀密度略微下降,基體密度大幅下降；各含量的ATP/Al2O3氣凝膠復(fù)合材料的抗壓強度均高于純A1203氣凝膠的抗壓強度,且抗壓強度隨ATP用量增加呈先快速增后緩慢減小的趨勢,ATP(26.09wt%)/Al2O3氣凝膠復(fù)合材料的抗壓強度高達74.55MPa,較純A1203氣凝膠的抗壓強度(26.74MPa)增強了近3倍；加入ATP后氣凝膠復(fù)合材料的隔熱性能變的更好。最后,探索了ATP對氧化鋁氣凝膠力學(xué)性能的增強機制,選用常壓干燥方法制備A1203氣凝膠和ATP/Al2O3氣凝膠復(fù)合材料分別從相組成、微觀形貌、比表面狀況以及熱穩(wěn)定性等方面著手比較分析。通過SEM和TEM分析表明ATP晶束在復(fù)合材料中作為骨架存在,使氧化鋁顆粒附著并蔓延生長成三維網(wǎng)絡(luò)結(jié)構(gòu),從而起到提高氣凝膠復(fù)合材料的力學(xué)性能；通過分析不同溫度下材料的比表面積和孔結(jié)構(gòu)參數(shù),表明ATP可以有效的抑制氧化鋁顆粒的燒結(jié),使氧化鋁氣凝膠更有利于在高溫下使用,如添加ATP后熱處理溫度從500℃.升高到900℃時,氣凝膠比表面積損失從43.94%降低到34.37%,孔容積損失從48%降低到7.34%;通過XRD、FT-IR、TGA分析,發(fā)現(xiàn)氧化鋁相仍保持原有的晶型、分子結(jié)構(gòu),說明ATP的加入不會破壞氧化鋁氣凝膠一些基本性質(zhì),如用作催化劑及催化劑載體的性質(zhì)和熱穩(wěn)定性等。
[Abstract]:Alumina aerogels not only have the basic properties of general aerogels, but also have excellent high temperature stability. The disadvantages of poor mechanical properties seriously restrict its practical application. Attapulgite ATP is a kind of water rich magnesium-rich aluminosilicate clay mineral with unique layer chain crystal structure which has excellent adsorbability. In view of its unique structure and stable physical and chemical properties, this paper uses attapulgite as reinforcements to prepare high strength alumina aerogels by direct drying at atmospheric pressure. The experimental process was optimized in terms of the ratio of H 2O and EtOH, the amount of propoxypropane oxide and the addition of ATP. Finally, it was determined that the best way of adding H _ 2O: EtOH3: 7voland propylene oxide to alumina sol was to prepare stable ATP suspensions and then add them to alumina sol. The effect of ATP content on mechanical properties of A1203 aerogel composite was studied. The results showed that the apparent density of aerogel composite decreased slightly and the matrix density decreased significantly after adding ATP. The compressive strength of ATP/Al2O3 aerogel composites with different contents was higher than that of pure A1203 aerogels. The compressive strength of ATP / Al _ 2O _ 3 aerogel composites increased rapidly first and then decreased slowly with the increase of ATP content. The compressive strength of the composite was as high as 74.55 MPA, which was nearly three times higher than that of pure A1203 aerogel. After the addition of ATP, the thermal insulation properties of the aerogel composites became better. Finally, the enhancement mechanism of ATP on the aerogel properties of alumina was explored. A1203 aerogel and ATP/Al2O3 aerogel composites were prepared by atmospheric pressure drying method. SEM and TEM analysis show that the ATP crystal beam exists as a skeleton in the composites, which makes the alumina particles adhere and grow into a three-dimensional network structure. By analyzing the specific surface area and pore structure parameters of the aerogel composites at different temperatures, it is shown that ATP can effectively inhibit the sintering of alumina particles. The alumina aerogel is more suitable for use at high temperature, such as the heat treatment temperature after adding ATP from 500 鈩，

本文編號：1542239