炭/炭复合材料用煤沥青的改性及性能研究

以对甲基苯甲醛(4-methyl benzaldehyde,简称4-MB)为改性剂,在对甲苯磺酸(PTS)的作用下对煤沥青进行了改性研究.采用傅立叶红外光谱和核磁共振氢谱对煤沥青改性机理进行分析;采用扫描电镜观察改性煤沥青的形貌;采用热解重量分析仪分析改性沥青的热行为.实验结果表明,对甲基苯甲醛在酸性催化剂的催化作用下与煤沥青发生亲电取代反应,改性后煤沥青出现纤维结构,改性沥青的耐热性优良,残炭率大大提高.因此,改性后的煤沥青有望作为优质的炭材料基体前驱体.     

二乙烯基苯改性煤沥青的热行为研究

以中温煤沥青为单体,二乙烯基苯为交联剂,在对甲苯磺酸（PTS）的催化作用下对煤沥青进行改性。采用差示扫描量热法（DSC）和热重－差热分析（TG－DTA）对改性前后的煤沥青进行热行为分析。研究表明,经过改性后煤沥青结晶组分的存在形式、数量以及相转变方式发生很大变化;改性后煤沥青的表观活化能降低、反应活性变大;改性后煤沥青的热分散起始温度显著提高、失重率明显降低。因此,经过改性的煤沥青可作为炭材料优良的基体前驱体。     

对甲基苯甲醛改性煤沥青的原位成纤机理研究

以对甲基苯甲醛为改性剂,在对甲苯磺酸的作用下对煤沥青进行了改性,并对改性后煤沥青的原位成纤机制进行研究。采用FT IR和1H NMR对改性煤沥青的化学结构进行分析,采用SEM对改性煤沥青的原位成纤形态进行观察。研究表明,对甲基苯甲醛能够与煤沥青发生亲电取代反应,使煤沥青中的活性小分子交联形成大分子。此外,改性煤沥青中出现很多微纤,随着改性时间的增加,纤维直径越来越大,最后形成分布均匀且线性很好的纤维束。因此,经过对甲基苯甲醛改性后的煤沥青有望成为优质的炭材料基体前躯体。     

煤沥青及改性煤沥青研究应用进展

煤沥青粘结力良好、抗滑性能优异,广泛应用于传统工业领域以及新材料领域,但煤沥青加热熔融时产生苯并芘等有毒物质,因此改性煤沥青备受关注。综述了煤沥青以及改性煤沥青的研究进展,介绍了煤沥青的改性机理,对煤沥青路用的可行性进行了分析。随着对改性煤沥青研究的日趋深入,未来煤沥青有望在筑路材料领域取代沥青。煤沥青作为路用沥青不仅可以使资源再利用,还可以降低筑路成本。     

改性纳米氧化锌对煤沥青延伸性能的影响

利用纳米氧化锌对煤沥青进行改性研究,考查了改性温度,分散方式,纳米氧化锌的添加量对煤沥青延伸性能的影响,优化了煤沥青的改性工艺,并对煤沥青的改性原理进行了探讨。     

聚乙二醇改性煤沥青半焦结构及其性能研究

以聚乙二醇-200和聚乙二醇-400为改性剂、对甲苯磺酸为催化剂对煤沥青进行改性,研究改性煤沥青的化学性质、成焦的晶体结构和显微结构。结果表明,改性后的煤沥青β树脂含量提高了51.90%-55.18%,芳核的缩合度和骨架振动吸收频率显著增大;改性反应主要发生在芳环的氢位上。在800℃时的残炭率比未改性煤沥青增加了18%;此外,在低于160℃时,经聚乙二醇-400改性后的煤沥青黏度低于同温度下未改性的煤沥青黏度,而经聚乙二醇-200改性的煤沥青黏度则高于同温度下未改性的煤沥青黏度。经聚乙二醇-200改性的沥青所制半焦纤维组织结构明显改善;其有序性和堆积高度也显著提高。     

添加剂对煤沥青的改性作用及沥青焦性能的影响

通过考察添加剂加入量与煤沥青的甲苯不溶物含量、软化点、析焦量以及所得沥焦的抗氧化性和石墨化活性的关系,探讨了添加剂对煤沥青的改性作用及其对沥青焦性能的影响。实验结果表明：在煤沥青中加入适当的添加剂可提高煤沥青的甲苯不溶物含量和析焦量,加入添加剂的煤沥青炭化后所得沥青焦的抗氧化性和石墨化活性均得到显著提高,但氧化残余物含量有所上升。该沥青焦经2300℃高温石墨化处理后仍表现出优良的抗氧化性。     

煤沥青的改性及中间相结构研究

以对甲苯磺酸(PTS)为催化剂,研究了改性温度、时间和改性剂苯甲醛用量对改性煤沥青(MCTP)中间相显微结构产生的影响。研究表明,当苯甲醛/煤沥青(CTP)质量比为30/100、反应温度为150℃和反应时间为15h时得到的MCTP,其中间相呈不完全纤维组织结构;XRD分析表明,通过苯甲醛改性煤沥青,有利于提高中间相光学组织结构的有序性。FT-IR分析表明,改性后芳核骨架振动吸收频率增大,提高了芳核的缩合度;1 H-NMR分析表明,改性过程中的改性反应主要发生在HA上,并对改性过程可能发生的反应机理进行了分析。     

稻壳木质素/SiO2复合物改性煤沥青热解行为的研究

研究了稻壳木质素/SiO2复合物（LSH）改性煤沥青的热解行为。采用了偏光显微镜、X射线衍射（XRD）分析、场发射扫描电镜（FESEM）等技术对改性煤沥青的焦化产物中间相的形貌和结构等进行分析。研究表明,LSH含量和炭化工艺对中间相光学组织结构的影响很大;随LSH含量的增加,改性煤沥青越来越难石墨化,LSH与煤沥青混合的越来越不均匀。     

煤沥青的改性及其机理研究进展

煤沥青具有资源丰富、价格低廉等优点,但其残炭率低,可以通过改性来提高其残炭率。简要介绍了改性煤沥青的制备方法及近几年来国内外改性煤沥青的发展状况,并探讨了其机理。由于煤沥青组成复杂,并不能知道其确切的反应机理,只能根据测试结果提出其可能的改性机理。     

炭/炭复合材料用基体前驱体煤沥青的研究动态

综述了近年来炭／炭复合材料用基体前驱体煤沥青的研究动态，重点阐述了不同改性方法对煤沥青的残炭率及高温流变性能的影响，指出了开发综合性能优良的改性煤沥青是制备低成本高性能炭／炭复合材料的关键。     

前驱体对炭泡沫孔结构的影响

分别以煤沥青、石油中间相沥青和AR沥青为前驱体制备炭泡沫材料。采用GPC测定前驱体分子量,SEM观察所制炭泡沫的孔结构,光学显微镜测量所制炭泡沫的孔径及其分布。结果发现,由于煤焦油沥青不含中间相,且QI含量较高,导致在实验条件下不能直接制备出合格的炭泡沫。以石油中间相沥青和AR沥青为原料均能制备出具有分布均匀开孔结构,且微观各向异性的炭泡沫。由AR沥青制备的炭泡沫呈现平均孔径较小(212μm)、孔壁较薄、孔径分布较窄(180μm~300μm)、开孔率较高、以及韧带排列较规整等特点,表明低QI含量、低分子量且分布较窄的前驱体有利于发泡。     

Effects of pressure on the pore formation of carbon/carbon composites during carbonization

In this study, porosity and graphitizability of coal tar pitch with the treatment pressure were investigated. 4-directional carbon/carbon composites (4D C/C) were made from the matrix precursor of coal tar pitch through the process of impregnation and carbonization. Then the effects of applied pressure during the densification on the composites were observed. The matrix pitch which had 600 bar applied during the carbonization process had one and a half times less pore area ratio than that treated at 1 bar. When the pitch was heat treated up to 2300°C after the high pressure carbonization, the degree of graphitization was improved on a small scale and the crystal size tended to reduce. As the applied pressures to 4D C/C composites increased from 1 to 600 bar, the densification ratio was greatly improved. In the pore size distribution of the 4D C/C composites, the macropore portion was decreased while the mesopore portion increased, when high pressures were applied.     

Influence of processed carbon black in the filler composition on the characteristics of baked carbon mixes

Several carbon products such as carbon brushes, special nuclear carbons, seal rings, etc. require carbon black in the filler composition. In the present study, the raw carbon black was mixed with a coal tar pitch and the resulting carbon mix was shaped, calcined and finally crushed into a fine powder for its subsequent use. The influence of this modified (processed) carbon black in the filler composition on the characteristics of the final calcined petroleum coke, processed carbon black and coal tar pitch-based carbon mixes has been investigated.     

The effect of graphite addition on the mechanical and tribological properties of pitch-based granular carbon composites

The present work deals with the effect of graphite addition on selected mechanical and tribological properties of pitch-based granular carbon composites. Three pitches (a commercial impregnating coal tar pitch, an air-blown pitch and a thermally treated coal tar pitch) and anthracite particles as reinforcing material were used to prepare carbon composites to be tested as carbon brake pads. These carbon composites show good compression strength (from 25.8 to 94.2 MPa) but unstable and high friction coefficients (>0.5). Experimental results have showed that small amounts of graphite addition (2.5 and 5.0 wt%) lead to carbon materials with more stable and lower friction coefficient (<0.3). So, graphite addition promoted the reduction in the wear rate. Finally, compressive strength of carbon composites prepared with modified pitches significantly increases after addition of small amounts of graphite with values from 94 to 128.8 MPa.     

Physical characteristics of baked carbon mixes employing coal tar and petroleum pitches

A study of the physical characteristics of baked carbon mixes employing coal tar and petroleum pitches as the binder has been made to explore their relative suitability in the fabrication of carbon products. The study reveals that coal tar pitch is the most suitable binder and a petroleum pitch of the same softening point leads to a carbon product of much inferior characteristics. Raising the softening point of the petroleum pitch from 78 to 150° C or adding 10 parts of carbon black in the lower softening point pitch, increases the density, strength and also the electrical resistivity of the baked carbons. The addition of 10 parts of carbon black to the higher softening point petroleum pitch leads to a carbon product with further improved values of density and strength, which are comparable to those obtained with the coal tar pitch. However, the electrical resistivity also is marginally increased. It appears that a petroleum pitch of high aromaticity may fulfill the requirements expected of a good binder.