广西气刀土高分散性能对卫生陶瓷性能的影响

用美国LS230激光粒度分析仪测定了气刀土原料的颗粒组成，其分散后的颗粒组成处于微米一亚微米级范围，数量分布统计数据为≤1．0μm粒级达97％以上。平均颗粒仅0．255μm，具有高分散性能；在坯料中加入4％～7％的广西气刀土原料替代等量的苏州土原料，使制品体积密度增加、气孔率和吸水率降低。分析原因是气刀土的高分散性能促进了坯体的固相烧结所致。     

利用广西气刀土原料研制高档卫生陶瓷

在对广西气刀土原料性能研究的基础上,进行了在卫生陶瓷坯料、釉料中的应用研究。坯料中加入4%～7%的广西气刀土原料替代等量的2#苏州土,在釉料中引入4～6%的气刀土原料替代1#苏州土,可以生产出理化性能和外观质量达到了美国ASMEA112.19.2M-1998标准要求的高档卫生陶瓷产品。引入广西气刀土原料使泥浆性能增强、厚化系数降低、湿坯硬度特别是内硬度明显提高、干坯抗折强度增大;制品体积密度增加、气孔率和吸水率降低;增强釉面乳浊效果、提高釉面白度,保证和提高产品的热稳定性能。     

专利信息

<正>一种面釉及其制备方法本发明公开了一种面釉,其特征在于,该面釉的组分重量比为:哑光熔块90%～96%、气刀土4%～6%、羧甲基纤维素钠0.08%～0.2%、工业三聚磷酸钠0.30%～0.36%、陶瓷解胶剂0.20%～0.26%;还包括上述原料总比例的30%～36%水。该面釉的制备工艺流程如下:原料进厂检验配料球磨检测除铁过筛     

合成氨原料气的超高效除油净化

本文从原理、结构、技术性能及经济效益分析等方面论述了中、高压合成氨原料气的超高效除油净化,首次将凝聚式过滤机理与方法应用于合成氨工业领域。采用不锈钢丝毡折叠滤芯与微米级超细玻璃纤维复合滤芯两级过滤,研制成功了具有国际先进水平的合成氨原料气专用除油过滤器,可有效去除亚微米级油雾微粒,免除催化剂油中毒,消除事故隐患。     

合成气的超高效除油净化

本文讨论凝聚式过滤机理与方法。采用不锈钢丝毡折叠滤芯与微米级超细玻璃纤维复合滤芯两级过滤,研制了具有国际先进水平的合成氨原料气专用除油过滤器,可有产去除亚微米级油雾微粒,免疫除催化剂油中毒,消除事故隐患。     

降低原料气净化系统脱硫溶液消耗

甲醇装置原料气净化系统运行问题多，操作困难，脱硫溶液消耗高，成为影响生产的一大难题。通过对原料气生产和净化系统各物相组成和杂质的分析，找出了问题的主要原因，采取了一系列的技术改进措施，使原料气净化系统脱硫溶液消耗降低，生产运行稳定。     

纳米SiC—Si3N4复合粉体制备材料的显微结构

以自制的纳米ＳｉＣ－Ｓｉ３Ｎ４复合粉体为原料，用气压烧结的方法制备陶瓷复合材料。对此材料用ＴＥＭ和ＨＲＥＭ电镜显微分析的结果发现两种不同的显微结构：纳米－微米结构和亚微米－微米结构。对两种结构的形成机理作了初步的探讨。     

纳米SiC－Si_3N_4复合粉体制备材料的显微结构

以自制的纳米ＳｉＣ－Ｓｉ＿３Ｎ＿４复合粉体为原料，用气压烧结的方法制备陶瓷复合材料。对此材料用ＴＥＭ和ＨＲＥＭ电镜显微分析的结果发现两种不同的显微结构：纳米－微米结构和亚微米－微米结构。对两种结构的形成机理作了初步的探讨。     

合成氨“双甲”工艺在原料气净化中的优势

合成氨原料气的净化是生产中至关重要的工序，原料气（CO＋CO2）微量超高将会导致氨催化剂中毒而使生产无法运行。由于原料气净化的能耗问题决定着合成氨的综合效益，近年来，许多专家学者在原料气净化方面做了大量的工作。随着耐硫低温变换催化剂的开发和精脱硫技术的发展，许多中小氮肥厂在原料气净化中已经相继出现了联醇、“双甲”等工艺。“双甲”工艺是在深度低变甲烷化工艺上发展起来的一种新的净化工艺，实践证明它有着其他工艺无法比拟的优势。     

三级脱硫理论与实践

本文介绍了甲醇原料气的三级脱硫工艺，经三级脱硫后，原料气中硫化物降至0．5ppm（体积）以下，完全满足甲醇生产的需要。     

Factorial Design of Experiments in Ceramics, II

This series of experiments illustrates the application of factorial design to the study of the unit operations of a semivitreous body formed by extrusion. The first two experiments were concerned with body preparation and forming; the first identified the factors responsible for variance in the system and the second (the present experiment) was designed to locate the optimum value of these factors that would maximize the fired modulus of rupture more accurately. The factors responsible for the variance were (1) particlesize distribution, (2) water of plasticity, and (3) entrapped air. In the second experiment two factors were used to represent the particle-size distribution, (1) the Ajax clays which are classified on the basis of amount below 2 p and (2) the kaolin to ball clay ratio. Entrapped air was eliminated in the second experiment. The center of the second experiment as represented by the Ajax clays was moved to the finer sizes. The center as represented by the kaolin to ball clay ratio was moved to the coarser sizes. The levels of the water of plasticity remained at 22 and 28%. It was found that the maximum modulus of rupture fell outside the limits of water of plasticity and the particle-size distribution as represented by the Ajax clays whereas a ratio of 39.5% Ajax clay to 10.5% ball clay would maximize the fired modulus of rupture.     

FUNDAMENTAL STUDY OF CLAY: VII,EFFECT OF PARTICLE SIZE ON PROPERTIES OF CASTING SLIPS*

Binary and ternary mixtures were made of 0.2- to 0.4-μ and 0.8- to 1.6-μ size purified fractions of clay and of 16- to 44-μ size purified flint. Specific gravity, deflocculation point, and hydrogen-ion concentration determinations were made on each composition to obtain the same apparent viscosity. Small cylinders were prepared by solid casting, and the shrinkage, porosity, and modulus of rupture of the dried specimens were measured. The general conclusions are as follows: (1) The packing of particles and the ratio of the plastic to the nonplastic components affect all slip properties; (2) the best combination of properties for casting slips was obtained at the composition corresponding to the closest packed system; (3) the casting time and drying shrinkage, both very small for bodies containing 20 to 25% of clay, increase together with the fine component; (4) the porosity of the dried casts is greatly affected by the particle-size distribution of the batch; (5) the minimum porosity of 28.5% obtained in this work is much lower than that of the standard sanitary body, which has a porosity of 35.5%; and (6) the particle-size control of casting slips not only will provide uniformity of the products but will also permit the desired variations in the properties of casting slips and cast bodies.     

Sugarcane Bagasse Ash as a Potential Quartz Replacement in Red Ceramic

Sugarcane bagasse ash (SCBA) is an industrial waste that contains silicon and aluminum oxides as the major components and iron, calcium, magnesium, and potassium oxides as the main minor components. In this paper, SCBA from one Brazilian factory was characterized and tested for its influence on the ceramic properties of clay/ash ceramic probes. Prismatic probes were pressed (18 MPa) using a ceramic mass mixed with 0%, 5%, 8%, and 10% ash. The probes were fired at temperatures between 800° and 1200°C. X-ray diffraction, X-ray fluorescence, thermal analysis (differential thermal analysis, thermogravimetric analysis/differential thermogravimetric analysis), and tests for texture (particle-size analysis), flexural strength, and linear shrinkage were carried out to characterize the samples. The results showed that the amount of ash to be incorporated will depend on mainly the composition of clay but also ash, and indicated that the clay used in this work can incorporate up to 10% weight of ash to produce solid bricks. The results also showed an improvement in ceramic/ash properties up to sintering temperatures higher than 1000°C.     

Major Factors That Influence Bleaching Performance

The three major factors which affect bleaching performance are type of clay, bleaching method, and oil quality. These are discussed in order. Under the first are such topics as purpose of clay in industry, source of raw material, clay types, physical structure, effect of activation on structure, variation in effectiveness of clays produced from different raw materials, and mechanism of the clay’s action. Also covered is the effect of the clay’s properties-moisture, apparent bulk density, specific gravity, acidity, pH, hydrated silica, particle-size distribution, and the theory of variability. Under the second are effect of bleaching conditions, such as temperature, time, agitation, temperature of clay addition, vacuum versus atmospheric bleaching; commercial methods including atmospheric batch, vacuum batch, vacuum continuous; and effect of oil quality. Under the third are response of different color pigments to bleaching, effect of moisture, oxidation, and organic impurities in the oil. Of the three factors, oil quality has the greatest influence upon bleaching performance. Presented at the AOCS Short Course, East Lansing, Aug. 29-Sept. 1, 1966.     

Practical Particle-Size Analysis of Clays: I, Sample Preparation

Wide variations in particle-size data from different laboratories for the same clay were thought to be due to dissimilar preparatory techniques. It was proposed to attempt to establish universally acceptable conditioning procedures based on determination of deflocculant requirement, most effective electrolyte, and method of dispersion. Three commonly employed dispersing agents were tested over a range of percentages on four selected whiteware clays. Both high-intensity agitation and low-intensity stirring were tried. It was found that all the sodium polyphosphate salts tested were equally effective and that with them complete dispersions could be attained by a minimum of agitation. Electrolyte requirements for complete dispersion were found to relate directly to points of minimum viscosity of deflocculated 50% clay-water slips.     

Effect of Particle-Size Distribution on the Microstructural Evolution in the Intermediate Stage of Sintering

The effect of particle-size distribution on microstructural evolution in the intermediate stage of sintering of powder compacts was investigated. The evolution of pore channels was dominated by particle-size distribution but independent of sintering temperature. Moreover, a powder compact with a fine particle and uniform size distribution could prolong the intermediate stage of sintering, which in turn effectively inhibited grain growth. The mechanisms of evolution and pinch off of the pore channels of the powder compact with different particle-size distributions were discussed.     

Factorial Design of Experiments in Ceramics, l

A factorial design of experiment is one in which a variable is evaluated at all levels of all other variables. This type of experiment was applied to the unit operations in body preparation and forming by extrusion. Drying and firing unit operations were not considered, and the variance due to these operations was minimized by duplication. The variables or factors were (1) particle-size distribution at three levels, (2) water of plasticity at two levels, (3) entrapped air at two levels, and (4) two replications. Analysis of variance was used to determine the significant effects. It was found that 95%. ₀f the total variance of the drying shrinkage was accounted for by the particle-size distribution, water of plasticity, and two interactions; 95% of the total variance of the dry modulus of rupture was accounted for by particle-size distribution, water of plasticity, entrapped air, and two interactions; 52% of the total variance of the firing shrinkage was accounted for by the particle-size distribution; 87% of the total variance of the fired modulus of rupture was accounted for by the particle-size distribution, water of plasticity, entrapped air, and three interactions. Since a tunnel kiln makes it possible to control the firing operation closely and with no changes in composition, close control of the particle-size distribution, water of plasticity, and entrapped air should make it possible to produce more uniform ware. The slope constants for the factors were also determined which show the most efficient path leading to the development of optimum conditions necessary for maximizing a desired property.     

Sintering of Bimodally Distributed Alumina Powders

The densification of alumina powders prepared to have a bi-modal particle-size distribution with a coarse-to-fine particle-size ratio of ≊ 10 can be predicted to a first approximation if the densification of the fine and coarse powders is known. Deviations from model prediction were attributed to compositional heterogeneity. Microstructural observations of bimodal powders show that only the fine powder undergoes grain growth. Thus, the grain-size distribution becomes more uniform than the initial particle-size distribution.     

动态过滤条件下核孔膜分级截留率的研究

利用旋叶压滤机与核孔膜的理想组合，通过实验验证与理论分析研究了在高分散物系情况下核孔膜对具有不同形状、一定粒度分布的悬浮液的分级截留特性。给出原料液、滤液的粒度分布规律，定义了颗粒截留率的概念，最后对膜的堵塞问题进行了讨论并提出初步建议。     

Coarsening Kinetics of the Tetragonal Phase in a Magnesia-Partially-Stabilized Zirconia

The coarsening kinetics of the tetragonal phase in a magnesia-partiallystabilized zirconia at 1420°C was examined using transmission electron microscopy and found to be controlled by volume diffusion. The rate constant was larger and the particle-size distribution was broader than predicted by the Lifshitz–Slyozov–Wagner theory of particle coarsening. A volume fraction modified coarsenng theory was found which better fits the experimental rate constant and particle-size distribution.