炭材料生产中煤沥青流变性能的调节

煤沥青流变性能对炭材料生产影响极大,煤沥青流变性能的合适调节及相应工艺参数的优选对于提高炭材料质量有着重要的作用。文章讨论了混捏、成型、焙烧和浸渍过程中影响煤沥青流变性能的因素,分析了工艺参数变化对煤沥青流变性能的调节作用,提出了改善煤沥青流变性能的措施。     

高性能炭材料生产用煤沥青的研究

研究了软化点在评价煤沥青聚合程度中的作用；描述了热聚合改质过程中煤沥青热解缩聚行为，分析了中温煤沥青热聚合改质过程中各种沥青组分随热聚合温度和热聚合时间的转变规律，探讨了QI组分影响煤沥青热聚合改质的机理，认为原料煤沥青所含原生QI炭微粒促进了热聚合改质过程中煤沥青芳烃分子的聚合；描述了煤沥青的流变性能及其在炭材料实际生产中的意义，研究了中温沥青和改质沥青高温流变性能的差异，探讨了硬脂酸和油酸对煤沥青的改性作用；分析了煤沥青的热解缩聚特征，研究了升温速率对煤沥青热解缩聚的影响。     

炭／炭复合材料用基体前驱体

本文介绍了炭／炭复合材料用基体前躯体煤沥青的几种改性方法，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。     

中国炭材料用煤沥青的生产和应用

介绍了中国煤沥青资源生产和应用现状，剖析了影响煤沥青市场的几个因素，探讨了改质煤沥青的应用前景以及在炭材料生产中应用时面临的问题，讨论了中国煤沥青质量评价体系，并对炭材料生产用煤沥青的质量指标进行了详细的分析。     

中国炭材料用煤沥青的生产和应用

文章介绍了中国煤沥青资源生产和应用现状，剖析了影响煤沥青市场的几个因素，探讨了改质煤沥青的应用前景以及在炭材料生产中应用时面临的问题，讨论了中国煤沥青质量评价体系，并对炭材料生产用煤沥青的质量指标进行了详细的分析。     

黏结剂用量对炭-石墨材料的影响

在炭-石墨材料制备过程中黏结剂煤沥青用量对材料的各项性能有重要的影响。本文对不同黏结剂煤沥青含量的生坯微观结构,以及炭-石墨材料制备工艺的关键参数进行了研究,为炭-石墨材料的制备提供参考。     

炭/炭复合材料用浸渍剂煤沥青研究进展

本文介绍了炭/炭复合材料用浸渍剂煤沥青的结构组成与性能特点,分析了影响煤沥青浸渍性能的关键因素,总结对比了近几年浸溃用煤沥青改性方法的优缺点.指出煤沥青的开发和生产应该兼顾残炭率、流动性、黏度和软化点等因素,从而减少浸渍次数,降低炭/炭复合材料的生产成本.     

两种沥青炭微观结构和性能的对比研究

将高温煤沥青和浸溃荆沥青在92MPa下炭化，在2500℃下对所得沥青炭进行石墨化处理；测试了所得沥青炭的体积密度、开孔率、比表面积（SBET）；利用扫描电子显微镜（SEM）观察了所得沥青炭的显微结构；利用X射线衍射方法（XRD）检测了所得沥青炭石墨化处理后的石墨化度；测试了所得沥青炭的氧化性能；测试了沥青炭试样的比热容、导热系数、热扩散率和线膨胀系数。结果表明：在92MPa下，两种沥青炭有着相近的密度和开孔率；浸渍剂沥青炭的SBEt高于高温煤沥青炭；浸渍荆沥青炭为流线型结构，高温煤沥青炭为镶嵌型和域型并存的结构；流线型结构沥青炭石墨化度较高；高温煤沥青炭的抗氧化性能要好于浸溃荆沥青炭；随着沥青炭石墨化程度的增大，比热客、导热系数、热扩散率都增大，而线膨胀系数减小。     

煤沥青流变性和煤沥青对炭素骨料焦浸润性的研究

煤沥青的流变性是影响黏结剂对骨料浸润性的重要指标,研究煤沥青的流变性,对制定混捏条件,保障糊料和炭素制品的质量具有指导意义.本文主要研究了煤沥青对炭素骨料石油焦(无烟煤)的浸润性及沥青的流变性能,探讨了煤沥青的黏度与软化点、喹啉不溶物之间的关系,最终找到了炭素材料在混捏过程中最佳混捏的黏度范围,这对提高铝用炭素材料质量,降低阳极消耗,延长铝电解槽寿命将起到积极的推动作用.     

浸渍剂沥青和黏结剂沥青渗透性对比研究

选择两类具有相近流变性能的黏结剂沥青和浸渍剂沥青,模拟炭材料的微孔分布测定了两类沥青的渗透率,对比研究了浸渍剂沥青和黏结剂沥青的渗透性能差异。结果表明,浸渍剂沥青的渗透性能远优于黏结剂沥青,浸渍剂沥青的渗透率为黏结剂沥青相应值的3.54~22.13倍,两类煤沥青的渗透性差异是由于其QI含量不同造成的,浸渍剂沥青极低的QI含量(0.2%以下)大大降低了煤沥青向多孔滤材中的渗透阻力,为提高浸渍效果创造了有利条件。     

升温速率对煤沥青热解缩聚的影响

用TGA对煤沥青的热失重过程进行了研究,分析了煤沥青的热解缩聚特征,并对中温沥青和改质沥青热解缩聚行为进行了比较,研究了升温速率对煤沥青热解缩聚的影响,发现快速升温使煤沥青组份更多地分解逸出,不利于提高煤沥青的结焦值。     

The manufacture of high-value carbon from coal-tar pitch

World-wide, 17 million ta^?1 of coal-tar are obtained as a by product in the chamber coking process for the production of metallurgical coke. Refining of this aromatic raw material yields coal-tar pitch which is the traditional coal-derived starting material for the manufacture of carbon precursors and carbon artefacts. Considerable progress has been made in the elucidation of the physical and chemical nature of this material by means of chromatography, n.m.r. spectroscopy, thermal analysis and chemical reactions schemes. The dominant fields of application of pitch are the manufacture of pitch coke and electrode binders. Delayed coking and horizontal chamber coking are the technologies currently used for the production of cokes with low sulphur and metal content, for anodes for the aluminium-refining industry and the electric steel process. Coal-tar pitch, low in quinoline-insolubles (QI), is an excellent raw material for the manufacture of needle-cokes with a low coefficient of thermal expension (CTE). The separation of inherent QI can be performed via gravity settling in aliphatic hydrocarbon mixtures, by centrifugation in a disc separator or by filtration. The possible co-carbonization with aromatic petroleum-derived residues yields premium coke suitable for the manufacture of UHP-electrodes. New developments in the production of coke from coal-tar pitch aim to improve coke yields and increase anisotropy (i.e. low CTE and high electrical conductivity values). Further technological progress has been made in the manufacture of hard pitch which can be used as a starting material for the production of pitch coke in the chamber coking process and for the production of electrode binders by means of a continuous flash process with optimized thermal and pressure treatment of pitch, thus facilitating the ‘tailored’ manufacture of binder pitches of different qualities.     

电极沥青粘结剂性能评价参数相关性的研究

以两个国外电极沥青粘结剂产品为参考样,选用典型国产原料以热化学改质法和调和法制备出工业分析指标与参考样处于同一水平的两组煤沥青粘结剂试样;对各组粘结剂试样和相应的参考样的元素组成、流变学性质、热动态行为、平均分子量及其分布以及各评价参数间的相关性进行了研究;就引入与其应用性能直接相关的评价因子的可能性进行了探索。     

A novel method to obtain a petroleum-derived mesophase pitch suitable as carbon fibre precursor

This paper studies a novel method for the preparation of mesophase pitches suitable as carbon fibre precursors. A series of thermally treated petroleum pitches with mesophase contents ranging from 10.8 to 52.2 vol.% was obtained from pitch A-240. Separation of the phases was initially attempted by hot filtration, a suitable method for separating the phases in thermally treated coal-tar pitches. Although filtration failed for the petroleum samples, the behaviour observed led to the development of a new separation method that consists in the sedimentation of the mesophase. This method, after optimisation, yielded pitches with mesophase contents up to 97 vol.%, which were easily spun into carbon fibres of reasonable mechanical properties.     

Determination of pitch volatility

The normalized distillation procedure is not a universal test for measuring the volatility of pitch. It has been found that during this test the liquid sample is exposed to temperatures in excess of 400 °C and decomposes extensively. Therefore, the distillate measured includes not only the low-boiling constituents originally present in the sample but also those formed by thermal decomposition. This has been observed in the case of petroleum pitches and not with coal-tar pitches. A new method has been developed for measuring the volatility of pitches, based on the diffusion through a small orifice into a stream of nitrogen of hydrocarbon vapours emanating from a large-size sample maintained at 200 °C. The hydrocarbons in the stream of nitrogen are measured with a flame-ionization detector. The peak height obtained during this measurement is calibrated against a standard mixture of methane in nitrogen. The signals from it are related to the concentration of volatile hydrocarbons over the heated sample of pitch and are expressed in gram atoms carbon per cubic metre of gas at the temperature of measurement. The volatility method was compared with the distillation test ASTM D-2569 for pitches and evaluation test ASTM D-972-56 for lubricating oils and greases. The procedure was found suitable for routine control testing of hydrocarbon materials (pitches) with very low volatility.     

Rheological characteristics of coal tar and petroleum pitches with and without additives

An extensive study of rheological characteristics of coal tar and petroleum pitches with and without additives, namely, petroleum coke, natural graphite and carbon black has been made. It is found that all pitches, pure or mixed with a carbon additive are not Newtonian as reported in the literature, but behave Theologically as Bingham plastics with certain yield stress and plastic viscosity at all temperatures of measurement between 85–180°C. The yield stress and plastic viscosity both decrease with increase in temperature of the pitch. A pure petroleum pitch having the same softening point as that of a coal tar pitch is found to have a lower viscosity compared to that of the latter at all temperatures of measurement. This suggests that the criterion of softening point as a measure of suitability of a coal tar pitch binder in the manufacture of artificial carbon is not sufficient for petroleum pitches. Addition of ten parts of carbon black by weight of pitch results in a considerable decrease in viscosity change with temperature of the coal tar pitch compared to almost insignificant change in the case of the petroleum pitch of the same softening point. However, the addition of petroleum coke or natural graphite makes the pitch more viscous but does not change the temperature dependence of viscosity of either of the two types of pitches. The implications are discussed.     

The influence of primary QI on the oxidation behaviour of pitch-based C/C composites

Three unidirectional C/C composites were prepared from PAN-based carbon fibres and three coal-tar pitches obtained from the same parent coal-tar pitch but differing in their primary QI content. The effect of the amount of primary QI present in pitches on the air reactivity of pitch-cokes and C/C composites was studied by thermogravimetric analysis. The oxidation of pitch-cokes was performed at 10°C min⁻¹ up to 1000°C. The air reactivity of C/C composites was assessed from the weight loss curves obtained under isothermal conditions in the temperature range of 500 to 575°C for 4 h. The topography of the oxidized composites was examined by scanning electron microscopy. The results showed that pitch-cokes were more reactive than carbon fibres because the presence of QI particles increased their reactivity. With the increase of primary QI content in the pitches, C/C composites showed a higher percentage of carbon matrix, with a finer optical texture, fewer microcracks and less closed porosity. The air reactivity of the composites was affected by both chemical and physical factors, the extent of oxidation determining which of these exerted the greater influence. At low conversions the reactivity was decided by both QI content and the optical texture of the matrix. At high conversions the porosity of the composite was the determining factor.