本文選題：煤瀝青　切入點：中間相炭微球　出處：《湖南大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：瀝青中間相炭微球(MCMB)是一種制造高密高強(qiáng)石墨材料的優(yōu)質(zhì)前驅(qū)體,有關(guān)其改性處理和制備工藝的理論研究在實驗室和工廠得到了廣泛深入的研究并取得較為豐碩的成果。大量研究表明,β樹指含量為5%-9%的MCMB因具有良好的自燒結(jié)性能和隨機(jī)取向性,適合于制備高性能高強(qiáng)高密石墨材料。由于本研究所選用的商用MCMB中揮發(fā)份含量僅為7.68wt%且β樹指含量較低(2.9wt%),自燒結(jié)性能較差,因此本文提出了首先采用溶液混合法制備煤瀝青改性MCMB,克服粘結(jié)劑添加量較少而分散不均勻的問題并改善MCMB自燒結(jié)性能,然后再采用常規(guī)等靜壓成型工藝制備高密高強(qiáng)MCMB基石墨材料的新思路,期望能為低揮發(fā)份含量MCMB在高強(qiáng)高密石墨材料制備中的應(yīng)用提供理論與實驗指導(dǎo)。首先考察了煤瀝青改性前后MCMB的結(jié)構(gòu)與熱失重性能變化規(guī)律,研究了煤瀝青改性MCMB的燒結(jié)行為及其對石墨材料性能的影響。結(jié)果表明,以THF為溶劑,采用溶液混合法可在MCMB粉體表面均勻包覆一層煤瀝青,改性后的粉體中仍有少量殘余的THF。在焙燒(炭化)過程中,生坯試樣隨熱處理溫度的升高均呈先膨脹后收縮的變化趨勢,且收縮率遠(yuǎn)大于膨脹率。與純MCMB壓制的生坯試樣相比,煤瀝青改性MCMB壓制的生坯試樣膨脹階段的溫度上限由450℃C提高至600℃C。600℃C-1100℃之間生坯試樣的收縮率、失重率不斷增大,電阻率也隨著有序度的提高而急劇下降,在焙燒過程中應(yīng)減小該溫度范圍內(nèi)的升溫速率以防止產(chǎn)品開裂。適當(dāng)增加瀝青含量可通過增大高溫?zé)崽幚磉^程中的收縮率提高石墨材料的致密度。其次研究了煤瀝青種類和含量對改性MCMB粉體及其所制備的石墨材料結(jié)構(gòu)和性能的影響。實驗表明,MCMB粉體中的瀝青主要以鋪展或超細(xì)微粒的形式附著在顆粒表面,少量以大顆粒的形式隨機(jī)分散在MCMB顆粒之間,其中MS改性MCMB顆粒的表面較粗糙,附著物的覆蓋面積最大。三種瀝青對MCMB的改性效果排序為：中溫瀝青(MS)改質(zhì)瀝青(MP)高溫瀝青(HS),當(dāng)瀝青含量為10wt%、成型壓力為150MPa時,所得石墨材料的抗折強(qiáng)度分別為56.9MPa、42.7MPa和27.7MPa。適當(dāng)提高成型壓力和瀝青含量可進(jìn)一步提升石墨材料的強(qiáng)度、密度、硬度及導(dǎo)電性能。最后研究了溶劑種類、脫溶劑溫度和時間對石墨材料性能的影響。結(jié)果表明,當(dāng)脫溶劑溫度為90℃和脫溶劑時間為12h時,以THF作溶劑、改質(zhì)瀝青改性MCMB制備的石墨材料的抗折強(qiáng)度和體積密度分別為41.0MPa和1.85g/cm3。以THF作溶劑的瀝青改性MCMB基石墨材料性能優(yōu)于以甲苯(TOL)作溶劑的瀝青改性MCMB基石墨材料的性能,甲苯等揮發(fā)物的大量排除延遲到了300℃之后,即生坯膨脹和致密化重排效應(yīng)最為劇烈的階段,阻礙了顆粒間的融并,導(dǎo)致炭/石墨材料孔隙率提高及力學(xué)性能和電學(xué)性能的下降。
[Abstract]:Pitch mesophase carbon microsphere (MCMB) is a high quality precursor for manufacturing high density and high strength graphite materials. The theoretical research on the modification treatment and preparation process has been extensively and deeply studied in laboratory and factory. A large number of studies have shown that MCMB with 尾 -tree index content of 5- 9% has good self-sintering property. Energy and random orientation, It is suitable for the preparation of high performance high strength and high density graphite materials. Because the volatile content in commercial MCMB is only 7.68 wt% and the 尾 -tree finger content is lower than 2.9 wtC, the self-sintering property is poor. In this paper, firstly, the coal bitumen modified MCMB is prepared by solution mixing method, which can overcome the problem of less binder addition and uneven dispersion, and improve the self-sintering performance of MCMB. Then the conventional isostatic pressing process was used to prepare high density and high strength graphite materials based on MCMB. It is expected to provide theoretical and experimental guidance for the application of low volatile content MCMB in the preparation of high strength and high density graphite materials. Firstly, the structure and thermogravimetric properties of MCMB before and after modification of coal pitch were investigated. The sintering behavior of coal bitumen modified MCMB and its effect on the properties of graphite materials were studied. The results showed that a layer of coal pitch could be uniformly coated on the surface of MCMB powder by solution mixing method with THF as solvent. There is still a small amount of residual THF in the modified powder. During the calcination (carbonization) process, the green samples show a tendency of first expansion and then shrinkage with the increase of heat treatment temperature, and the shrinkage rate is much larger than that of the pure MCMB compacted green sample. The upper limit of the temperature in the expansion stage of the raw green sample pressed by MCMB modified by coal asphalt is increased from 450 鈩，

本文編號：1626652