煤灰和氧化铝混合物合成的莫来石

本文研究的目的旨在论证由精选过的煤灰和氧化铝粉的混合物合成莫来石的可行性。收到精选过的煤灰有Ｆ和Ｃ两个级别，用来合成莫来石。精选的Ｆ级煤灰已成功地合成了莫来石，其性能和工业用莫来石等同。然而，收到的Ｆ和Ｃ两个级别的煤灰不适宜于合成膨胀性小的莫来石。     

莫来石及多孔莫来石的研究和应用

高温性能稳定,抗热震性能好的莫来石是一种重要的工程陶瓷材料。概述了莫来石的结构、性能,以及在工业上的应用,并对多孔莫来石陶瓷的研究进展和应用进行了介绍。针对莫来石室温力学性能较差的缺陷,讨论了氧化锆和颗粒增韧莫来石的方法。最后,对多孔ZTM陶瓷发展前景进行了展望。     

用红柱石制备莫来石纤维增强材料的实验研究

以红柱石为原料，对高温下红柱石－莫来石相变过程的微观物相结构及莫来石纤维特征进行了实验研究。认为，利用红柱石的高温相交，在陶瓷烧结过程中直接制取莫来石纤维是可行的。     

M60莫来石的应用研究

利用M60莫来石可以制造出抗热震性能好的制品,引入刚玉细粉和石英中颗粒后可以制造出具有良好抗高温蠕变性能的制品。     

莫来石晶须的制备与表征

用硫酸铝与高岭土作为反应物料、Na2SO4为反应介质,采用熔盐合成法制备莫来石晶须.通过XRD、XRF和SEM等研究煅烧产物;运用正交试验法研究煅烧温度和保温时间对莫来石晶须生长的影响,结果表明:制备出莫来石晶须的主要成分为Al2 O3和SiO2,两者的摩尔比为1.3-1.443;煅烧温度和保温时间分别为900℃和2h...     

Sol-Gel法制备莫来石粉末的研究

本文研究了以正硅酸乙酯（TEOS）和硝酸铝为原料，用溶胶-凝胶法制备莫来石粉末的过程。探讨了温度和pH值对Al2O3-SiO2凝胶时间的影响；用IR和XRD研究了凝胶在热处理过程中的晶相变化。研究结果表明：温度升高，凝胶时间缩短；pH=3时，溶胶的聚集速度减慢，胶凝时间较长；莫来石相是经铝硅尖晶石转化而成．铝硅尖晶石在1000℃开始转化为莫来石，至1250℃全部转化；制备的莫来石粉末晶粒尺寸为100-200nm。     

锆莫来石耐火材料的显微结构研究

用ＸＲＦ，ＯＭ，Ｓｔｅｒｅｏｌｏｇｙ等方法来锆莫来石耐火材料试样进行了剖析研究，测试了一系列数据，说明了锆莫来石耐火材料的显策结构和所具有的良好性能因果关系及其结构－性能之间存在的必然联系。     

莫来石/刚玉质耐火材料与碱性沉积物腐蚀反应的实验研究

莫来石及刚玉质耐火砖,通常用于生产球团铁矿的回转窑,从球团铁矿回转窑里沉积下来的物质,用于实验室进行耐材/沉积物的反应实验及沉积组分对耐火砖的渗入实验。实验材料分为块状和粉末状两种形式。碱金属碳酸盐(包括钠和钾)作为腐蚀剂,促进化学反应。耐材/沉积物试样界面的形态变化及活跃的化学反应将通过电子显微镜记录。X射线衍射分析表明,碱金属与砖中的莫来石发生反应,钠比钾反应更为明显。霞石(Na2O·Al2O3·2SiO2)、六方钾霞石及钾霞石(K2O·Al2O3·2SiO2)和白榴石(K2O·Al2O3·4SiO2)这些晶相的形成是碱金属和耐火砖之间反应的结果。这些晶相导致砖石材料出现20%~25%的体积膨胀,从而加速腐蚀。     

刚玉莫来石材料烧成过程研究

本文对刚玉莫来石材料的烧结过程进行了较为系统的研究,探索了从低温到高温的烧结过程中,坯体烧成收缩、吸水率、密度、抗弯强度等随烧成温度的变化规律。刚玉莫来石材料在从低温到高温的烧成过程中,经历了四个典型的特征阶段:粘土和细粉的收缩阶段;莫来石细晶大量形成阶段;莫来石晶体长大产生疏松效应阶段;液相烧结阶段。这四个阶段都有各自典型的性能参数变化规律。     

氧化铝-莫来石复合粉对莫来石烧结行为的影响

将莫来石先驱体溶胶预先引入到硫酸铝水溶液中 ,干燥后经 12 0 0℃煅烧获得氧化铝 -莫来石复合粉料。研究了该粉料与硅溶胶混合获得的混合粉的烧结行为 ,并与氧化铝、莫来石晶种和硅溶胶三相混合获得的混合粉的烧结行为进行了分析比较。其中 ,两种混合粉料均是以理论莫来石组分进行配比 (Al2 O3∶SiO2 =72∶2 8) ,并且两种混合粉中莫来石晶种的质量分数均为 5%。实验结果表明 :前者在 1450℃烧结 2 0min即实现完全莫来石化 ,其显微结构为晶须状莫来石 ;后者在 150 0℃烧结 2 0min实现完全莫来石化 ,其显微结构为针状莫来石     

利用粉煤灰与铝矾土合成莫来石的研究

用粉煤灰直接制备M45莫来石以及与铝矾土混合合成M60莫来石,可大大降低莫来石的合成成本。采用综合热分析仪(TG-DSC)、X射线衍射仪(XRD)和扫描电子显微镜(SEM)对样品进行表征。结果表明:经800℃煅烧2 h并经除铁处理的粉煤灰可直接作为低牌号莫来石(M45)使用;用预处理的粉煤灰和铝矾土混合制备高牌号莫来石(M60)适宜的烧结温度为1 000℃;合成的莫来石的主要组分符合中国烧结莫来石标准(YB/T 5267—2005)。     

关于莫来石陶瓷焊补颗粒熔融时间模拟计算的探讨

通过对莫来石陶瓷焊补传热过程剖析,建立了单个喷补颗粒传热过程模型,借助于稳定态传热公式,计算出不同喷补颗粒加热熔融时间,这为莫来石陶瓷焊补颗粒配比及其操作规程的制订提供了重要的理论依据。     

Kinetic study on the anisotropic grain growth of elongated iron-containing mullite

Elongated iron-containing mullite exhibiting anisotropic grain growth was prepared using fused silica, α-alumina, and Fe₂O₃ powders as raw materials at elevated temperatures. The effects of different Fe₂O₃ contents on the anisotropic growth of mullite columnar crystals were investigated, and phase compositional analysis and structural characterisation were carried out by X-ray diffraction and field emission scanning electron microscopy. The kinetic index and activation energy for the anisotropic grain growth of elongated mullite crystals were calculated, and the surface energy of each crystal plane of the elongated crystal and the solid solution behavior of the iron ions in the mullite were calculated using the density functional theory (DFT) approach. It was found that the addition of Fe₂O₃ promotes the anisotropic grain growth of mullite, and the aspect ratio of the elongated crystals increased upon increasing the Fe₂O₃ content. The solid solubility upper limit of the iron-containing mullite in this system is 9 wt% of iron addition. After sintering at 1973 K, for Fe₂O₃ contents of 3, 6, and 9 wt%, the growth kinetics indices obtained by calculations in the longitudinal direction were 2.22, 2.50, and 3.85, while the reaction activation energies were 457.3, 442.1, and 411.9 kJ mol⁻¹. The calculation results on the surface energy of the elongated mullite crystal showed that the smallest surface energy is on the (001) crystal plane, which is the preferred growth direction. Upon comparison of the surface energies for different Fe₂O₃ contents on the (001) surface, a decrease was observed upon increasing the quantity of Fe₂O₃, and both the growth tendency of the mullite crystals and the aspect ratio of the elongated crystals also increased. The refractoriness under load of the prepared elongated iron-containing mullite was 1664 °C, demonstrating its excellent high-temperature mechanical properties.     

应用量子化学计算研究溴与汞反应的动力学参数

引言汞是挥发性的有毒重金属元素。燃煤中含有微量的汞,这些汞在煤燃烧时会释放到烟气中,燃煤烟气中汞主要以3种形态存在:颗粒Hg(Hgp)、气态氧化Hg(Hg2+)和气态单质Hg(Hg0)。     

粉煤灰细粉添加量对多孔莫来石材料的影响

为了提高粉煤灰的资源化利用,在m(漂珠):m(氢氧化铝):m(V2O5):m(AlF3)=45:55:4:3的混合料中分别添加不同量(每100 g混合料分别添加0、5、10、20、30 g)的粉煤灰细粉,以PVA溶液为结合剂,经干料混匀、泥料搅拌、泥料陈腐、挤制成型、1100℃保温2 h烧成制备莫来石试样,然后检测其致...     

Flux mechanism of compound flux on ash and slag of coal with high ash melting temperature

The melting temperature of Z coal ash was reduced by adding calcium–magnesium compound flux(W_(CaO)/W_(MgO)=1). In the process of simulated coal gasification, the coal ash and slag were prepared. The transformation of minerals in coal ash and slag upon the change of temperature was studied by using X-ray diffraction(XRD). With the increase of temperatures, forsterite in the ash disappears, while the diffraction peak strength of magnesium spinel increases,and the content of the calcium feldspar increases, then the content of the amorphous phase in the ash increases obviously. The species and evolution process of oxygen, silicon, aluminum, calcium, magnesium at different temperatures were analyzed by X-ray photoelectron spectroscopy(XPS). The decrease of the ash melting point mainly affects the structural changes of silicon, aluminum and oxygen. The coordination of aluminum and oxygen in the aluminum element structure, e.g., tetracoordinated aluminum oxide, was changed. Tetrahedral [AlO_4] and hexacoordinated aluminoxy octahedral [AlO_6] change with the temperature changing. The addition of Ca~(2+) and Mg~(2+) destroys silica chain, making bridge oxide silicon change into non-bridge oxysilicon; and bridge oxygen bond was broken and non-bridge oxygen bond was produced in the oxygen element structure. The addition of calcium and magnesium compound flux reacts with aluminum oxide tetrahedron, aluminum oxide octahedron and silicon tetrahedron to promote the breakage of the bridge oxygen bond. Ca~(2+) and Mg~(2+) are easily combined with silicon oxide and aluminum oxide tetrahedron and aluminum. Oxygen octahedrons combine with non-oxygen bonds to generate low-melting temperature feldspars and magnesite minerals, thereby reducing the coal ash melting temperatures. The structure of kaolinite and mullite was simulated by quantum chemistry calculation, and kaolinite molecule has a stable structure.     

高纯莫来石原料合成工艺研究

利用工业氧化铝与煤系轻烧高岭土或高纯石英砂为原料合成高纯莫来石,研究了添加剂(分别为滑石、ZnO和锆英砂)、合成温度、工艺过程对莫来石相含量及体积密度的影响。采用XRD定量分析的K值法计算出莫来石相的含量。结果表明:用工业氧化铝与煤系高纯高岭土合成出的莫来石相含量高于用石英砂与工业氧化铝合成的试样,在其中加入1%ZnO和1%锆英砂作添加剂的试样(其w(Al2O3)=68%),在氧化气氛下采用1380℃3h和1580℃3h二次保温煅烧工艺,合成的莫来石相含量达到97%,体积密度达到2.89g·cm-3。     

氢气分子与碳纳米管缺陷相互作用的量子化学计算

采用分子力学和量子化学计算了氢气分子与椅式(5,5)、(6,6)和齿式(10,0)碳纳米管上两类缺陷的相互作用引起的能量和微观参数的变化.碳纳米管的原子平均能量可以反映碳纳米管张力大小和共轭表面扭曲程度.在各类缺陷中,通过分析计算得到的吸附能和键能、键级、净电荷等微观参数,发现氢气分子经由去掉一个碳原子所形成且位于碳纳米管中部的缺陷进入管内的趋势最大;与此类缺陷的相互作用主要表现在与氢气分子几何距离最接近的3个碳原子上,通过它们对整个缺陷的微观性质发生影响,缺陷对称性有所降低,并且明显地富集了较多的负电荷,使净电荷的分布更为不均匀.     

高灰熔点煤灰熔融特性的可控调整研究进展

我国高灰熔点煤占煤炭储量的57%左右,直接用于气流床气化时将面临"积灰和堵渣"的问题,探索高灰熔点煤灰熔融特性的调控方法对气流床的稳定运行意义重大。主要分析了助熔剂和配煤对灰熔融温度的影响规律;并从矿物质演变机理的角度综述了助熔剂(Fe2O3,Ca O,Mg O,Na2O,K2O和复合助熔剂)、配煤和软件分析(FactSage软件热力学计算和Gaussian量子化计算)如何分析和实现高灰熔点煤灰熔融特性的可控调整;最后阐述了采用支持向量机进行煤灰熔融温度的预测存在精度高的优势。提出了寻找新型助熔剂以增强灰熔融温度调控的准确性和基于支持向量机模型建立煤灰成分与灰熔融温度的关联式,进而指导和优化气化配煤煤种和比例的选择,为高灰熔点煤的清洁高效利用提供理论支持。     

Preparation of high strength and low thermal conductivity mullite refractories based on reconstruction of fly ash

The preparation of refractories with both low thermal conductivity and high strength are continuously pursued in industrial furnaces. In this work, mullite refractories with low thermal conductivity and high strength were developed using fly ash as main raw material, and the influence of the quantity of fly ash and sintering temperature on the structure and properties of mullite refractories were investigated. The results show that mullite refractories with low thermal conductivity and high strength could be prepared by using fly ash in large proportion; the thermal conductivity of the samples decreased with the addition of the fly ash and increased with the increase of sintering temperature; the cold compressive strength and modulus of rupture of samples all are enhanced with the increase of sintering temperature, which is attributed to the formation of more elongated mullite by the reconstruction of fly ash at high temperature. For the mullite refractory using 65.04 wt% fly ash treated at 1600°C, the thermal conductivity was .732W/(m·k) at 1000°C, and the cold compressive strength and modulus of rupture could reach 143.5 ± 5.7 MPa and 47.0 ± 4.1 MPa respectively. It can be considered to use as a prospective work lining in industrial furnaces to meet energy saving requirements.