骨料浸渍氧化铝浆体对高炉炭砖显微结构和性能影响

针对炭砖为主要原料电煅煤的多孔结构,采用真空浸渍浆体方法对电煅煤骨料进行处理来改善骨料的致密度,从而优化炭砖的微孔结构,提高炭砖性能.首先对电煅煤骨料进行真空浸渍氧化铝浆体处理,得到浸渍氧化铝电煅煤骨料(以下简称浸渍骨料),然后将浸渍骨料取代电煅煤骨料引入到炭砖中,借助场发射扫描电镜、压汞仪和CT扫描仪等研究了浸渍骨料对高温热处理后炭砖显微结构、微孔结构和性能的影响.结果表明:通过真空浸渍氧化铝方法,氧化铝填充进电煅煤骨料的开口气孔和裂缝中,使骨料更加致密.将浸渍骨料引入到炭砖中,炭砖经不同温度处理后的性能得到明显改善,如经1400℃处理后炭砖的耐压强度提高近50％,平均孔径降低至73 nm,<1μm孔容积率达到80％左右.炭砖性能的改善主要与引入更加致密的浸渍骨料和形成更多的原位陶瓷相有关.     

支持向量机算法对电锻煤基炭砖导热性能的优化及预报

导热系数是评价高炉炭砖性能的重要指标之一.本工作在传统电煅煤基炭砖的基础上,使用人造石墨逐步替换电锻煤细粉与骨料,系统研究了人造石墨引入量、焙烧温度等因素对炭砖导热性能的影响,并使用支持向量机回归建模分析算法建立了炭砖导热系数的数学模型.结果表明,人造石墨的加入有助于提升炭砖的导热系数,并降低导热性能的各向异性,但会影响炭砖的抗铁水溶蚀性能;由支持向量机建模分析得知,石墨含量与气孔直径对导热系数提高的影响较为明显;借助该建模方法获得了炭砖导热系数的预报拟合公式,该公式具有较高精度,可用于炭砖导热系数的优化与预报.     

四种不同产地无烟煤性能研究

对四种国产无烟煤的化学成分、氧化率和岩相结果进行了分析，以及用此四种无烟煤在相同工艺条件下制成的微孔炭砖试样进行了试验研究。结果表明，阳泉煤制成的微孔炭砖性能优良，且阳泉煤变质程度最好，是生产微孔炭砖最为理想的原料；宁夏太西煤只要控制好煅烧质量，也是生产微孔炭砖的优质原料。     

新型微孔炭砖的试制

本文介绍了炼铁高炉用新型微孔炭砖的试制概况。选用宁夏优质无烟煤经过电煅烧，原料配比中以电煅煤和石墨及部分添加剂为骨料，煤沥青作粘结剂试制出品质优良的新型微孔炭砖，对电煅烧工艺操作控制，本文给出了电阻率依赖于排料量和调整功率的回归方程。指出在稳定其电器参数条件下，控制好排料量是保证电煅烧无烟煤质量的主要因素。在微孔炭砖性能论述中，还给出了微孔炭砖的抗碱性依赖于石墨含量，炭砖的抗压强度依赖颗粒抗压碎强度，平均导热系数依赖石墨含量和石墨与焙烧温度交互作用的三个回归方程。同时还指出，微孔炭砖的抗压强度不仅受颗粒抗压碎强度的控制，而且还受焙烧过程中粘结剂沥青的结焦率所控制，因此，又给出了焙烧中沥青的结焦率依赖于粉子纯度、沥青用量、粉纯与沥青交互作用的回归方程。指出沥青与粉纯交互作用是影响焙烧结焦率的主要因素。微孔炭砖微孔形成的最低反应温度和最佳反应温度可由抗碱性和微孔容积依赖于焙烧温度的经验公式求出。同时还就兰炭试制的微孔炭砖质量指标与国内外优质炭砖实际指标做了对比。     

高温模压炭砖的研制

介绍了炼铁高炉用高温模压炭砖的研制概况。重点介绍了"抗铁水"炭砖研制情况,选用电煅煤和高温电煅煤为骨料,煤沥青作黏结剂在特制设备中快速压型烧结试制出高温模压炭砖。对原材料优化给出了炭砖的耐压强度、铁水溶蚀指数、透气度依赖于高温电煅煤含量的三个回归方程。还给出了3种炭砖的抗热震因子的结果。同时就远洋公司生产的高温模压炭砖质量指标与国内外优质炭砖进行了对比分析。     

两种不同铁水熔蚀炭砖微观结构分析

为提高高炉炭砖的抗铁水熔蚀性,对两种不同铁水熔蚀性炭砖进行了岩相和电子显微镜分析.炭砖的微观结果分析表明,无烟煤基质的炭砖抗铁水熔蚀性优于在原料中添加石墨的炭砖;往基质中加入Al_2O_3可大为改善炭砖的扰铁水熔蚀性;工艺上使Al_2O_3均匀分布是提高炭砖抗铁水熔蚀性的重要措施.     

高炉炭砖性能与原料的选择

对不同煅烧温度下不同原料配比的实验结果进行了分析，得出：山西阳泉四矿无烟煤、云南昭通小发路煤矿无烟煤不宜作炭砖原料；太西洗煤厂精洗煤是高炉炭砖的优质原料；贵州织金煤矿无烟煤如果煅烧条件适宜，也可作高炉炭砖的优质原料；提高骨料的石墨化度或提高原煤的煅烧温度，是提高高炉炭砖导热系数的有效途径。     

超细微晶石墨对电煅煤基高炉炭砖显微结构和性能的影响

以电煅煤和活性α-Al2 O3微粉为主要原料,硅粉和铝粉为添加剂,在埋碳条件下经1200℃和1400℃焙烧处理后制备出电煅煤基高炉炭砖(以下简称炭砖).在炭砖中添加超细微晶石墨,借助X射线衍射仪、场发射扫描电子显微镜、激光导热仪和压汞仪研究了超细微晶石墨的引入对炭砖物相组成、显微结构、导热性能及孔结构的影响,并与引入相同量鳞片石墨的试样作对比.结果表明:实验所用超细微晶石墨晶粒尺寸细小,并且呈现出薄片状结构,与电煅煤相比具有更高的反应活性.在炭砖中引入超细微晶石墨,促进了材料中碳化硅晶须的生成,提高了材料的耐压强度和导热系数,增大了材料中<1μm气孔的孔容积率.与添加相同含量鳞片石墨的试样相比,含超细微晶石墨试样的导热系数和平均孔径与其相当,耐压强度更优,在炭砖中具有很好的应用前景.     

石墨化无烟煤制备铝用炭阳极研究

采用高温石墨化炉将太西(TX)无烟煤进行热处理，部分替代煅后焦制备铝用炭阳极，先后考察了TX石墨化煤不同添加形式、添加比例对炭阳极质量的影响。结果表明，TX无烟煤在经过超高温处理后真密度、电阻率、石墨化度、固定炭、灰分、微量元素等指标有了很大的改善，但Fe元素的脱除效果不是很明显；相较于颗粒料的添加形式，采用粉料添加形式制备的阳极质量更优；随着粉料添加量的上升，阳极体积密度、真密度、电阻率、空气反应残余率等指标均明显提高，但CO₂反应残余率明显下降。     

铝电解槽用无烟煤基石墨化阴极材料的初步研究

选取优质电煅无烟煤,分别配以一定比例的石油焦和沥青焦作为骨料,与煤沥青混合后按照模压成型、焙烧、高压浸渍、二次焙烧和石墨化等常规炭素制品生产工艺流程制备石墨化阴极材料试样。考察了无烟煤和3种少灰料以不同配比混合制成的试样在焙烧和石墨化过程中的尺寸变化及理化性能变化规律,并通过对4种以单一原料制备的试样的理化性能分析,探讨了原料种类对试样性能的影响。结果表明,以无烟煤为主要原料,配以一定比例的少灰料作为骨料,通过适当的炭素工艺制备的石墨化阴极材料试样,其常规理化性能可以满足大电流铝电解槽用阴极材料的要求。     

铝电解槽用石墨化阴极材料的研究

以4种国产焦炭、3种国产煤沥青为原材料，采用热模压成型、一次焙烧、高压浸渍、二次焙烧和石墨化等工艺开展了铝电解槽用石墨化阴极材料的研究。在对原材料结构和理化性能分析的基础上，考察了原材料种类和配比不同的15个试样在热处理过程中的收缩率和体积密度的变化，并对石墨化后的试样的各项理化性能与工业发达国家生产的石墨化阴极炭块的性能指标进行了对比分析。结果表明，以国产焦炭和煤沥青为原材料，经过适当的混配和热处理工艺得到的石墨化阴极材料试样，其综合性能指标已达到铝电解槽对高性能石墨化阴极材料的要求。     

Title of simulation of the physicochemical processes of high-temperature treatment of carbon products in Acheson furnaces

A mathematical simulation technique for physicochemical processes occurring in the manufacture of electrode products in the Acheson graphitization furnaces was considered. The effects of the physicochemical properties of the carbon heat insulation of the furnace on the structure of its thermal field and the processes of mass transfer and gas evolution initiated by this field were studied. It was shown that, with the use of the carbon heat insulation based on anthracites from the Eastern Donbass, the homogeneity of the thermal field in the products treated can be substantially increased, whereas the thermal load on the refractory lining of the furnace can be decreased. The experimental data of commercial tests of different heat insulation compositions were given. The processes of silicon carbide formation in heat insulation were analyzed, and the areas of possible use of solid carbonaceous wastes from graphitization processes were determined.     

不同碳含量对镁碳砖性能的影响

研究了碳含量的变化对镁碳砖抗渣侵蚀性、抗氧化性能、高温抗折强度和热震稳定性的影响。研究结果表明：随碳含量增加,镁碳砖的体积密度、耐压强度降低;碳含量在6%~8%时,镁碳砖的高温抗折强度、热震稳定性、抗渣侵蚀性及抗氧化性能好;碳含量低,镁碳砖的抗渣侵蚀性降低;碳含量为14%时,镁碳砖的抗氧化性能最差。     

Graphitization thermal treatment of carbon nanofibers

Carbon nanofibers (CNFs) and carbon nanotubes have revolutionized the world of the nanotechnology due to their excellent mechanical, electrical and thermal properties. CNFs are graphitic fibers made of stacks of graphene layers aligned perpendicular, tilted or parallel to the fiber axis, thus resulting in different microstructures. Post-production treatments can be applied to CNFs to improve their performance in several applications. Among them, the heat treatment at high temperature to achieve the transformation of the CNFs into graphite (graphitization) or graphitized CNFs (graphitization heat treatment) has been studied in detail. This review covers the literature on this topic for the last 20 years, analyzing the structural and textural changes shown by the CNFs during graphitization, and how these changes influence their mechanical and electrical properties. Different techniques, particularly, high-resolution transmission electron microscopy, have allowed to determine the microstructure of these nanofilaments. A survey of the applications of graphitized CNFs is provided, these including additives for polymer reinforcement in composites, anodes in lithium-ion batteries, catalyst supports in fuel cells, hydrogen storage and others such as potential biosensors and catalysts in diverse reactions. In this regard, special emphasis is placed on the advantages (or disadvantages) of using graphitized CNFs instead of as-grown CNFs.     

B4C-C复合粉体的合成及其在低碳镁碳砖中的应用

以炭黑和硼酸为原料,采用碳热还原法合成了部分石墨化B4C-C复合粉体,并将其作为碳源和抗氧化剂用于低碳镁碳砖中. 研究了加热温度对B4C-C复合粉体合成的影响,分析了其物相结构、成分、形貌和粒度. 通过测定低碳镁碳砖的常规物理性能、抗氧化性和热震稳定性,考察了复合粉体对低碳镁碳砖性能的影响. 结果表明,随加热温度升高,B4C-C复合粉体的石墨化度增大,B4C含量下降,1900℃时石墨化度达23.26%,B4C含量为20%左右,复合粉体中除部分微米、亚微米级的B4C外,85%以上为纳米级的B4C和部分石墨化炭黑. 添加复合粉体的低碳镁碳砖具有良好的常规物理性能、抗氧化性和热震稳定性.     

碳纤维石墨化技术研究进展

碳纤维石墨化可以使其结构趋向于理想石墨结构，拉伸模量大幅提升，因此石墨化碳纤维广泛应用在航空航天等尖端技术领域。本文对比分析了碳纤维石墨化设备优缺点，详细介绍了激光超高温加热等新式石墨化方法及促进石墨化进程的相关工艺，进一步从微观结构层面分析影响力学性能的因素，为高模量碳纤维制备技术的研究提供理论及实践参考。指出目前主流的石墨体间接加热技术由于温度限制阻滞了碳纤维模量的进一步提升，克服高温限制且高效高质量、节能环保的石墨化技术是未来的发展趋势；应从组成碳纤维的分子层面去分析把握碳纤维的结构演变，进而优化控制石墨化工艺及设计相关石墨化设备，不断改善碳纤维石墨化结构，逐步趋向于力学性能的理论值。     

Influence of graphitization degree of carbon microspheres on properties of PET flame retardant

In this work, the influence of graphitization degree of carbon microspheres (CMSs) on flame retardancy of poly(ethylene terephthalate) (PET) composites was examined. The graphitized CMSs (abbreviated as, TCMSs) were prepared through an annealing treatment, and both the CMSs/PET and TCMSs/PET composites with variable filler amounts were fabricated by the melt blending method. The results suggested that the graphitization degree of CMSs played an important role in the flame retardancy of PET. On the one hand, the TCMSs acted as effective heat shields to delay the ignition time (TTI), improve the initial thermal decomposition temperature of PET, decrease the heat absorption, and enhance the limiting oxygen index (LOI) values. On the other hand, the graphitized TCMSs decreased both the peak heat release rate (PHRR) and fire risk (FGI) through the formation of a more compact crosslinked carbon layer of graphitized carbon. With the addition of 2% TCMSs, the LOI of TCMSs/PET composites increased from 21% (neat PET) to 26.3%, the PHRR value decreased from 531.90 to 332.46 kW/m², and the residue amount increased from 9.31% to 19.31%. Compared to the CMSs, the dispersion of TCMSs in PET matrix and tensile strength of TCMSs/PET composites were also improved. Thus, these novel graphitized TCMSs show promise as efficient flame retardants for future applications. POLYM. ENG. SCI., 58:1399–1408, 2018. © 2017 Society of Plastics Engineers     

Graphitization studies of anthracites by high resolution electron microscopy

Thirteen anthracites of various origin were studied by modern electron microscopy techniques, microdiffraction, bright field, dark field and lattice imaging in the raw and progressively heat-treated state. The anthracites are known to behave like hard carbons below HTT 2000°C and like soft carbons above 2500°C. We have found that flattening of the pores, which is not present in hard carbons, occurs in anthracites and that this flattening induces a preferred orientation of the carbon planes above 1700°C, which in turn allows graphitization. This evolution of the carbon structure, demonstrated for the first time, is the essential phenomenon for anthracites. It becomes hidden by the promoting effect of impurities included in anthracites, if their concentration is too high.