新型堇青石一莫来石窑具材料的研究

研究了以７５％莫来石＋２５％堇青石为骨料，７５％堇青石＋２５％莫来石结合剂的堇青石－莫来石和以堇青石结合莫来石的窑具材料的显微结构和性能，发现使用复合骨料和复合结合剂的窑具材料具有较优越的抗热震性，并对其机理进行了较详细的分析和讨论。     

堇青石/莫来石比值对硅微粉结合莫来石-堇青石窑具材料结构与性能影响

采用硅微粉结合的莫来石-堇青石窑具是固体废弃物综合利用，变废为宝的研究项目。硅微粉尘是硅铁电炉冶炼过程产生的大量烟尘，属于玻璃体，尺寸为纳米级，高活性，能促进窑具材料的烧结和提高窑具性能。经XRD和SEM分析结果，各试样存在四种晶相α-堇青石，β-堇青石，μ-堇青石和莫来石。堇青石/莫来石比值从2．33变化到1．5时，堇青石从83．8％增加到85．3％，莫来石从15．4％降低到14．7％；堇青石，莫来石比值从1．5降低至0．67时，堇青石含量随比值下降而降低，莫来石随比值降低而增加。综合分析结果确定3^#为最佳配方，存在的堇青石与莫来石的晶相比例合理，抗折强度最高(27．41Mpa)，1次和10次热震抗折强度保持率最高(67％和46％)，气孔率和收缩率较低，体积密度最高，这种配方的窑具材料热稳定性好，强度高，使用寿命长。     

莫来石-堇青石耐火材料工艺特性及应用前景

阐述了莫来石—堇青石窑具的机理和工艺特性，并结合了我国目前窑具行业的现状和存在的问题，分析了国内外窑具差距的原因以及我国发展莫来石—堇青石窑具的迫切性、自身优势和广阔的市场前景。     

堇青石-莫来石立柱成分分析与断裂机理研究

堇青石-莫来石立柱是一种常用的陶瓷厂窑具材料,在高温烟气腐蚀下,堇青石-莫来石立柱通常发生断裂失效.本工作以陶瓷厂断裂失效堇青石-莫来石立柱为研究对象,采用X射线衍射、X射线荧光、扫描电子显微镜等技术测定分析了堇青石-莫来石立柱的化学组成与微观结构.结果发现:断裂失效后的堇青石-莫来石立柱组织中形成了大量玻璃相结构,伴...     

堇青石—莫来石棚板抗热震性能的研究

采用莫来石为骨料,堇青石为基料制作堇青石—莫来石棚板,研究莫来石与堇青石配比、骨料种类、烧成温度等因素对材料抗热震性能的影响。     

莫来石-堇青石窑具的现状与发展前景

叙述了我国窑具行业的现状和存在的问题。阐述了新型莫来石－堇青石窑具的工艺特点以及与国外窑具的差距。论述了我国发展莫来石－堇青石窑具的迫切性、自身优势和广阔的市场前景。     

试制棚板窑具过程中预合成堇青石、莫来石的探索

试制棚板窑具过程中预合成堇青石、莫来石的探索陈铁亮，王淑英，胡锦辉（唐山市陶瓷研究所，唐山０６３０２０）１前言在日用陶瓷生产中，为实现无匣烧成，我们进行了拥板赛具的试制。在试制过程中，确定了以堇青石－莫来石质为主攻方向。通过对国外窑具的认真调研分析，...     

高温烟气净化用多孔堇青石陶瓷支撑体材料的研制

以堇青石为原料，用震动热浇注成型工艺．通过调整骨料粒径等级、造孔剂及结合剂的加入量制备气孔率为48％，孔径为128μm，热稳定性好和机械强度高的高温烟气净化用多孔堇青石陶瓷支撑体材料。对影响材料性能的各种因素进行分析和探讨。     

沭阳兰晶石应用研究

1.前言国外陶瓷工业用窑具材料总的发展趋势是采用高性能人工合成原料,如合成堇青石、莫来石、钛酸铝等,而且均采用专业化生产。我国“八五”期间开展了为陶瓷工业用高性能窑具提供规模大、机械化程度高、产品质量稳定、成本低的优质堇青石合成原料以及复合钛酸铝原料的工业化生产技术研究,并最终形成专业化生产示范线。本文作者在合成堇青石研究已取得成果的基础上,近期又完成了合成堇青石新方法的研究。根据这一研究结果,认为绿泥石—兰晶石体系是合成堇青石的理想方法,并具有实用价值。本文就是在这一结论基础上进行的沭阳兰晶石在     

堇青石对镁铝尖晶石质耐火材料抗热震性能的影响

镁铝尖晶石堇青石复合耐火材料是以各种级配的镁铝尖晶石和1 ～Omm的堇青石为骨料,0.088 mm镁铝尖晶石和二氧化硅微粉为基质,加入硅溶胶结合剂制成的烧结耐火材料.所获得的材料经过1200℃烧结具有优良抗热震性以及满足要求的其他性能,随着堇青石掺量的增加,材料的抗折强度降低,抗热震性增强.     

原位反应烧成莫来石-堇青石复合材料及其特性(英文)

通过原位反应烧成方法制备了不同莫来石、堇青石含量比的复合材料。首先,根据堇青石和莫来石的理论化学组成,分别将高岭土、工业氧化铝和滑石混合,配制出堇青石生料粉(C粉)和莫来石生料粉(M粉)。然后,再将C粉和M粉按不同的设计比例混合,烧结制备出一系列莫来石-堇青石复合材料。添加V2O5添加剂,考察其对烧结复合材料的影响。并通过X射线衍射,微观结构观察,热力学性质检验,比较了不同莫来石、堇青石含量比的复合材料的特性。制备的莫来石-堇青石复合材料所用的烧结温度可降低至1380℃,且复合材料中堇青石和莫来石晶体发育良好,复合材料抗热震性好。     

Effects of partial substitution of calcium alumino-titanate on the properties and microstructure of mullite–cordierite composites

In order to realize the recycling of calcium alumino-titanate (CAT, a solid waste), the effect of small amounts (3–9% weight ratio) of CAT on the sintering properties of the mullite–cordierite system was investigated. The thermal-shock stability, volume stability, and mechanical properties of samples with different amounts of CAT were characterized and tested. The influence of CAT on the phase composition and microstructure of the mullite–cordierite system was also deduced from thermodynamic calculations. Experimental results, which agreed with the calculations, demonstrate that CAT could promote the close combination and aggregation of matrix materials, thus strengthening the consolidation process and enhancing desirable properties.     

Electrical properties and thermal expansion of cordierite and cordierite-mullite materials

Commercially available cordierite and mullite powders were used to obtain cordierite and composite materials with mullite content up to 65 wt.% by attrition milling, uniaxial pressing and sintering. The employed cordierite powders were the coarse, medium and fine single granulometric fractions and the binary mixtures of them with 30, 50 and 70 wt.% of the smaller size component. Mullite powder employed in composites was a 7 h-attrition milled one. The dielectric constant (), dielectric loss tangent (tan δ), resistivity (ρ) and thermal expansion coefficient () were measured. The influence of the porosity, mullite and glassy phase contents and grain size in the electrical parameters was analyzed. The thermal expansion coefficient as a function of the composition was studied.     

Effect of fluorine-containing additive on the synthesis and sintering of compositions from natural raw materials in the “cordierite –mullite” system

The influence of the small addition of topaz on the processes of mineral formation in the “mullite–cordierite” system with a variable ratio of cordierite and mullite has been investigated. For this purpose, a series of experiments with different compositions of the initial mixtures, that is, with predominance of cordierite over mullite (KM mixtures) and predominance of mullite over cordierite (MK mixtures), has been performed. The addition of topaz in the form of topaz concentrate has been introduced in the amount of 1% by the weight of the investigated mixtures. The samples have been fired at various temperatures, that is, samples from KM mixtures (at a temperature of 1100–1300?°C) and samples from MK mixtures (at a temperature of 1400–1550?°C. The activating effect of topaz on mineral formation and sintering processes is determined by complex influence of fluoride products of topaz thermal decomposition. These reactively gaseous fluorides partially activate the solid-phase mass transfer processes and then reduce the viscosity of high-temperature melt formed during firing that intensifies the processes of ceramic matrix consolidation.Porous polycrystalline cordierite–mullitе–corundum ceramics from the KM mixtures, which contains 70%–87% cordierite, 3%–12% mullite, and 4%–11% corundum with water absorption of 3.5%–8% and bulk density of 2.10%–2.12?g/cm³ at the firing temperature of 1300?°C, has been developed. Mullite ceramics with notably corundum content (not more than 8%) from the MK mixtures with various density degrees at the firing temperature of 1500–1550?°C, porous ceramics with water absorption of 3%–11%, and dense ceramics with water absorption of less than 1% have been produced.     

Novel cordierite-acicular mullite composite for diesel particulate filters

Cordierite-acicular mullite composites containing 0, 25, 50, 75 and 100 wt% of mullite were fabricated from waste MoSi₂ and commercial powders of Al₂O₃ and spinel (MgAl₂O₄). Careful oxidation of pulverised waste MoSi₂ rendered a precursor mixture of MoO₃ and amorphous SiO₂, which served as pore forming agent and SiO₂ source, respectively. Evaporation of MoO₃ at ～750 °C allowed production of highly porous cordierite-mullite ceramic composite after sintering in air at 1350 °C for 4 h. The combination of equiaxed cordierite grains and elongated (prism-like) mullite grains, resulted in unique microstructure with open porosity between 53.3 and 55.6 vol% which makes the obtained composite convenient for application as diesel particulate filter material. The presence of mullite affected four key thermo-mechanical properties which determine the thermal shock resistance of cordierite-mullite composite. The best thermal shock resistance was measured in composite containing 75 wt% of mullite. It was a result of improved thermal conductivity (1.081 W/mK) and bending strength (3.62 MPa) and relatively low values of coefficient of thermal expansion (3.8 × 10^?6 K^?1) and elastic modulus (2.27 GPa).     

莫来石-堇青石复合材料的制备与性能研究

由热压和液相烧结方法制得了具有各种莫来石含量和显微结构的莫来石-堇青石复合体.研究了各种烧结温度、时间、气氛条件下复合体的致密度和显微结构的改善.还研究了复合体弹性模量、断裂韧性、热膨胀系数与组成之间的关系.研究结果表明,复合体的断裂韧性随莫来石含量和杨氏模量线性增加,粗的针状莫来石由于其穿晶断裂模式而有较高的断裂韧性.     

Preparation of Mullite Cordierite Composite Powders by the Sol-Gel Method: Its Characteristics and Sintering

Mullite/cordierite composite powders containing different proportions of cordierite were prepared by the sol-gel method using boehmite, colloidal silica, and Mg(NO₃)₂·6H₂O. Mullite and cordierite sols were prepared separately and mixed to form the composite sol. Mullitization temperature depends on the cordierite content in the composite. Also, α-cordierite crystallizes at a lower temperature in a mullite-rich (MC20) composite. The XRD patterns of the powders calcined at 1450°C for 12 h showed that mullite and cordierite exist as two different phases, and no additional phases were observed. The IR absorbance spectra of composites showed characteristic peak corresponding to both mullite and cordierite. The sintered density of the powders increases with temperature up to 1450°C and decreases beyound the melting point of cordierite (1455°C). The microstructure of MC30 sintered at 1440°C for 3 h consisted of acicular grains, whereas in MC40 and MC50 equiaxed grain morphology was observed under similar sintering conditions. The flexural strength and Vickers hardness decreases with the increase of cordierite content in the composite. Dielectric constant and thermal expansion showed a similar behavior.     

堇青石加入方式对堇青石-莫来石窑具材料性能的影响

为满足锂离子电池正极材料烧成的需要,以堇青石、莫来石、高岭土和氧化铝为原料制备堇青石-莫来石窑具材料,研究了堇青石颗粒和细粉加入量对堇青石-莫来石窑具材料的常温性能、高温抗折强度和抗热震性的影响.并用XRD和SEM分析了试样烧后的物相变化与显微结构.结果表明:随着堇青石颗粒或细粉加入量从0到30％(质量分数),试样的线变化率、显气孔率、高温抗折强度增大,体积密度下降;而对常温抗折强度的影响不大,试样的耐压强度分别呈现下降或提高的趋势,试样的抗热震性先增加后降低,当堇青石颗粒含量为20％,细粉含量为20％时,试样的抗热震性最好.     

Properties of multiple oxide-bonded porous SiC ceramics prepared by an infiltration technique

Multiple oxide-bonded porous SiC ceramics were fabricated by infiltrating a porous powder compact of SiC and alumina with cordierite sol followed by sintering at 1300-1400°C in air for 3 hours. The microstructures, phase components, mechanical properties, and air permeation behavior of the developed porous ceramics were examined and compared with materials obtained by the traditional powder processing route. The porosity, average pore diameter, and flexural strength of the ceramics varied from 33 to 37 vol%, ~12-14 μm and ~23-39.6 MPa, respectively, with variation in sintering temperature. The X-ray diffraction results reveal that both the amount of cordierite and mullite as the binder increased with increase in sintering temperature. In addition, it was found that the addition of alumina in powder form effectively enhanced the strength due to formation of mullite in the bond phase in contrast to the samples prepared without alumina additive. To determine the suitability of the material in particulate filtration application, particle collection efficiency of the filter material was evaluated theoretically using single collector efficiency model.     

Effect of the processing on the production of cordierite–mullite composite

In this study, effect of process on the production of cordierite–mullite composite was studied. For this reason two different processing methods were used in the production of cordierite–mullite composites. In first process, in situ cordierite–mullite composites were produced from cordierite and mullite layers which were formed by using aqueous tape casting method. In second one, composite was produced by addition of pre-produced mullite powders (in different weight percents, 0–30) into cordierite starting powders. The results show that the addition of pre-sintered mullite powders to the cordierite slip has more effect on densification behavior and mechanical properties of composites than layered production method.