本文選題：BN材料 + 高分子網(wǎng)絡(luò)法　； 參考：《沈陽大學(xué)》2011年碩士論文

【摘要】：BN材料具有機械性能好、導(dǎo)熱性能高、化學(xué)性質(zhì)穩(wěn)定、抗氧化能力強等一系列優(yōu)異性能,在儲氫材料、催化劑載體等領(lǐng)域有著潛在的應(yīng)用價值。但到目前為止,BN在這些領(lǐng)域中并沒有得到廣泛應(yīng)用,主要原因是至今還沒有一種合適的方法合成出高產(chǎn)率、高純度、高比表面的BN材料。目前合成BN的方法有電弧放電法、化學(xué)氣相沉積法、球磨退火法、前驅(qū)體高溫?zé)峤夥ê虲模板法等。在這些方法中,電弧放電法、化學(xué)氣相沉積法操作復(fù)雜、成本高且產(chǎn)率低。前驅(qū)體高溫?zé)峤夥ê虲模板法常用于高比表面的BN合成,但前驅(qū)體高溫?zé)峤夥ㄉ婕暗挠行膀?qū)體難于合成,同樣產(chǎn)量低下,而C模板法則由于反應(yīng)后的殘余C雜質(zhì)難于去除導(dǎo)致所得BN粉體純度不高,且操作繁雜。因此,尋找一種簡便經(jīng)濟的方法來合成出高產(chǎn)率、高純度、高比表面的BN粉體將是非常重要的工作。 本文以廉價的硼砂和尿素為主要原料,采用網(wǎng)絡(luò)法制備BN前驅(qū)體并通過反應(yīng)合成出高純度、高比表面的BN粉體。并對高分子網(wǎng)絡(luò)形成機理,前驅(qū)體成分配比和網(wǎng)絡(luò)溶膠凝膠進行了研究。探討了碳源的選擇對于網(wǎng)絡(luò)凝膠的影響,研究了反應(yīng)溫度對BN粉體比表面、孔隙度、形貌的影響。還研究了BN粉體的合成工藝、反應(yīng)機理和微觀形貌。使用XRD、SEM、EDS、TEM和低溫N2吸附-脫附等檢測手段對BN粉體進行表征,優(yōu)化反應(yīng)條件。取得以下研究結(jié)果： 基于網(wǎng)絡(luò)法合成出硼元素和氮元素分布均勻的高分子網(wǎng)絡(luò)干凝膠。得出網(wǎng)絡(luò)劑最佳成分配比為：丙烯酰胺：N,N-亞甲基雙丙烯酰胺：過硫酸銨=140：4：25。利用網(wǎng)絡(luò)法對于粉體分散性的提高促進,得到分散性良好的BN前驅(qū)體,通過調(diào)節(jié)反應(yīng)時間,反應(yīng)溫度,成功的合成出顆粒粒度低、分散性好的高比表面BN粉體。明確網(wǎng)絡(luò)法制備BN粉體的最佳合成工藝為：在NH3氣氛中,300℃保溫2小時,675℃保溫2小時反應(yīng),產(chǎn)品經(jīng)過清洗除碳處理,最終可得到BN粉體。合成BN粉體平均孔徑在5.16nm左右,比表面為288.57m2/g,比現(xiàn)有資料報道的比表面有明顯提高。本合成方法簡單,易操作,合成溫度低,且產(chǎn)率高。
[Abstract]:BN has a series of excellent properties such as good mechanical properties, high thermal conductivity, stable chemical properties, strong oxidation resistance and so on. It has potential application value in hydrogen storage materials, catalyst support and other fields. But so far it has not been widely used in these fields. The main reason is that there is no suitable method to synthesize BN materials with high yield, high purity and high surface area. At present, the methods of BN synthesis include arc discharge, chemical vapor deposition, ball milling annealing, pyrolysis of precursor at high temperature and C template. Among these methods, arc discharge method and chemical vapor deposition method are complex, high cost and low yield. The precursor pyrolysis and C template method are often used in the synthesis of BN with high specific surface, but the effective precursor involved in the high-temperature pyrolysis of the precursor is difficult to synthesize, and the yield is also low. However, the C template rule is difficult to remove the residual C impurities after the reaction, which leads to the low purity and complicated operation of the BN powder. Therefore, it is very important to find a simple and economical method to synthesize BN powder with high yield, high purity and high specific surface. In this paper, borax and urea were used as the main raw materials, BN precursor was prepared by network method and BN powder with high purity and high specific surface was synthesized by reaction. The formation mechanism of polymer network, precursor composition ratio and network sol gel were studied. The influence of carbon source selection on the network gel and the effect of reaction temperature on the specific surface porosity and morphology of BN powder were studied. The synthesis process, reaction mechanism and microstructure of BN powder were also studied. The BN powder was characterized by TEM and N2 adsorption-desorption at low temperature, and the reaction conditions were optimized. The following findings were obtained: Polymer network xerogels with uniform distribution of boron and nitrogen elements were synthesized by network method. The optimum composition of the network agent is as follows: acrylamide: N- N- methylene bisacrylamide: ammonium persulfate 140: 4: 25. The BN precursor with good dispersity was obtained by using the network method to improve the dispersity of the powder. By adjusting the reaction time and reaction temperature, the low particle size and high specific surface BN powder with good dispersibility were successfully synthesized. It is determined that the optimum synthesis process of BN powder by network method is that the BN powder can be obtained by cleaning and decarbonization in the atmosphere of NH3 at 300 鈩，

本文編號：1932544