高岭土制NaA型分子筛（WMS）的工艺

高岭土制ＮａＡ型分子筛（ＷＭＳ）的工艺魏忠汉（江西省景德镇陶瓷学校景德镇·３３３００１）ＴｈｅＰｒｏｃｅｓｓｏｆｄｅｖｅｌｏｐｉｎｇＮａＡＷＭＳｏｆｋａｏｌｉｎ￥ＷｅｉＺｈｏｎｇｈａｎ（ＪｉａｎｇｘｉＣｅｒａｍｉｃｓｃｈｏｏｌ）１前言当前，国际间洗涤...     

12SiMoVNb低合金钢在小氮肥厂的应用

１２ＳｉＭｏＶＮｂ低合金钢在小氮肥厂的应用徐夙平（湖南省益阳地区氮肥厂）关键词１２ＳｉＭｏＶＮｂ钢，应用Ａｐｐｌｉｃａｔｉｏｎｏｆ１２ＳｉＭｏＶＮｂｌｏｗａｌｌｏｙｓｔｅｅｌｉｎｓｍａｌｌ－ｓｃａｌｅｎｉｔｒｏｇｅｎｆｅｒｔｉｌｉｚｅｒｐｌａｎｔｓ．...     

英语翻译技巧（13）

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玻璃弯曲强度的裂纹影响

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硫化铋微晶掺杂凝胶玻璃的显微结构研究

硫化铋微晶掺杂凝胶玻璃的显微结构研究叶辉，姜中宏（中国科学院上海光学精密机械研究所２０１８００）ＭｉｃｒｏｓｔｒｕｃｔｕｒｅＳｔｕｄｙｏｆＢｉ＿２Ｓ＿３ＭｉｃｒｏｃｒｙｓｔａｌｌｉｔｅＤｏｐｅｄＧｅｌＧｌａｓｓ￥ＹｅＨｕｉ；ＪｉａｎｇＺｈｏｎｇｈｏｎ...     

薄板玻璃的用途,组成和成形工艺

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微型机电系统在化学分析中的应用

微型机电系统在化学分析中的应用孙彦平（北方工业大学，北京１０００４１）孟晓雄（航天总公司７０７所，北京１０００１３）１ＭＥＭＳ的特点微型机电系统（ＭｉｃｒｏｅｌｅｃｔｒｏｎｉｃＭｅｃｈｉｎｅＳｙｓｔｅｍ，ＭＥＭＳ），简称为“微机械”。它是采用半导体加...     

行列式制瓶机上的电子凸轮

行列式制瓶机上的电子凸轮姜丰英（齐鲁莫尔玻璃机械有限公司２５５３１１）ＥｌｅｃｔｒｏｎｉｃＣａｍｓｏｆＩＳＦｏｒｍｉｎｇＭａｃｈｉｎｅ￥ＪｉａｎｇＦｅｎｇｙｉｎｇ（Ｑｉｌｕ－ＭａｕｌＧｌａｓｓＭａｃｈｉｎｅｒｙＣｏ．Ｌｔｄ）Ａｂｓｔｒａｃｔ：ＩｎＩ．...     

马来酐单酰胺染料的红外光谱研究

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分散染料应用于超细纤维的探讨肖学俊（苏州染料厂,苏州２１５００７）ＳｔｕｄｙｏｎｔｈｅＡｐｐｌｉｃａｔｉｏｎｏｆＤｉｓｐｅｒｓｅＤｙｅｓｏｎｔｈｅＭｉｃｒｏｆｉｂｅｒＸｉａｏＸｕｅｊｕｎ（ＳｕｚｈｏｕＤｙｅｓｔｕｆｆＰｌａｎｔ,Ｓｕｚｈｏｕ２１５００...     

脱硅高岭土制备莫来石材料的研究

莫来石是一种高级耐火材料,具有非常广泛的用途。现研究用脱硅高岭土为原料生产莫来石材料,以解决目前莫来石生产中存在的产品质量与生产成本不能兼顾的问题。高岭土经脱硅处理后,主要成分为没有活性的Al2O3和部分没有被脱去的SiO2,其铝硅氧化物摩尔比已超过莫来石。在脱硅高岭土中加入部分未煅烧的生高岭土粉,用来调节莫来石的成分,并作为莫来石成型的粘结剂,然后经成型、煅烧,制成莫来石制品。结果表明：这种方法生产莫来石,不用加入工业氧化铝,有望降低生产成本及提高莫来石的纯度。     

以粉煤灰和赤泥为原料烧结陶瓷工艺与性能研究

本文研究了在1050 ℃至1200 ℃之间温度对以粉煤灰赤泥为原料烧结陶瓷的物相和烧结性能的影响.结果表明:实验用粉煤灰原料的主要矿相组成为石英(SiO_2)和莫来石(3Al_2O_3·2SiO_2),赤泥原料的主要矿相组成有钙铝黄长石(Ca_2Al_2SiO_7)、石英(SiO_2)、钙铁榴石(Ca_3Fe_2+3(SiO_4)_3)和钙钛榴石(Ca_3TiFeSi_3O_(12));以粉煤灰赤泥为原料的5组不同配比试样在1200 ℃时试样气孔率相对降低,体积密度和抗压强度相对程度增大;其中5#试样在经1200 ℃烧结后的气孔率为1.67%,体积密度为2.10 g·cm~(-3),抗压强度为123.23 MPa,达到较好的烧结致密状态,试样主要物相是钙钠长石和莫来石.试样内莫来石的形成及玻璃液相的增加促进烧结并在1200 ℃达到致密烧结状态.     

Microstructure and mechanical properties of in-situ grown mullite toughened 3Y-TZP zirconia ceramics fabricated by gelcasting

In-situ grown mullite toughened zirconia ceramics (mullite-zirconia ceramics) with excellent mechanical properties for potential applications in dental materials were fabricated by gelcasting combined with pressureless sintering. The effect of sintering temperature on the microstructure and mechanical properties of mullite-zirconia ceramics was investigated. The results indicated that the columnar mullite produced by reaction was evenly distributed in the zirconia matrix and the content and size of that increased with the increase of sintering temperature. Mullite-zirconia ceramics sintered at 1500 °C had the optimum content and size of the columnar mullite phase, generating the excellent mechanical properties (the bend strength of 890.4 MPa, the fracture toughness of 10.2 MPa.m^1/2, the Vickers hardness of 13.2 GPa and the highest densification). On the other hand, zirconia particles were evenly distributed inside the columnar mullite, which improved the mechanical properties of columnar mullite because of pinning effect. All of this clearly confirmed that zirconia grains strengthened columnar mullite, and thus the columnar mullite was more effective in enhancing the zirconia-based ceramics. Simultaneously, the residual alumina after reaction was distributed evenly in the form of particle, which improved the mechanical properties of the sample because of pinning effect. Overall, the synergistic effect of zirconia phase transformation toughening with mullite and alumina secondary toughening improved the mechanical properties of zirconia ceramics.     

Cyclic Infiltration of Porous Zirconia Preforms with a Liquid Solution of Mullite Precursor

Composites of mullite and zirconia were fabricated via the cyclic infiltration of porous zirconia-based preforms with a liquid mullite precursor. The maximal amount of mullite precursor that could be infiltrated was dependent primarily on the initial open porosity of the preforms. When a zirconia preform with an initial open porosity of ∼58% was cyclically infiltrated to saturation, the open porosity was reduced to ∼43%, with a median pore diameter of 15 nm. After sintering at a temperature of 1500°C for 2 h, the saturation-infiltrated zirconia preforms could be densified to ∼98% of the theoretical density. In zirconia samples, infiltrated mullite had a tendency to coalesce into large, elongated grains as the sintering temperature was increased. The presence of infiltrated mullite did not have a significant effect on the zirconia grain structure. The distribution of mullite in the samples was nonuniform, and the distribution profiles varied as the number of infiltration cycles varied. Although the sintered density and hardness showed small improvements after saturation infiltration, the fracture toughness did not increase.     

锆刚玉莫来石-碳化硅复合材料的显微结构

采用OM、SEM、TEM及EDAX等手段研究了锆刚玉莫来石-碳化硅复合材料的显微结构。结果表明,ZrO_2及SiC均匀地分散于刚玉/莫来石构成的基质中。刚玉-刚玉(或莫来石)及莫来石-莫来石的晶间表面多数存在非晶质薄膜,但也有刚玉-莫来石两相直接结合的相界因扩散而形成固溶层。ZrO_2-刚玉(或莫来石)及SiC-刚玉(或莫来石)的相表面因相间扩散形成固溶层或扩散层而皆属直接结合。在刚玉和莫来石晶体里观察到有晶内ZrO_2存在,其形成原因可能是在烧结过程中,刚玉或莫来石晶体再结晶长大而包裹ZrO_2微粒所致。     

High‐temperature fracture toughness of mullite with monoclinic zirconia

Reactive sintering of zircon and alumina and zirconia additions to mullite are well‐established methods for improving the poor fracture toughness of mullite. While it is clear that transformation toughening is responsible for the improved toughness by addition of partially stabilized zirconia, it is not clear why adding unstabilized zirconia increases the toughness although microcracking and crack deflection have been suggested. Therefore, the fracture toughness of a mullite composite with 20 vol% unstabilized zirconia and a monolithic mullite were investigated at ambient conditions and at temperatures up to 1225°C. It was found that monoclinic zirconia increases the toughness at ambient conditions from the monolithic mullite value of 1.9 to 3.9 MPa·m^1/2. The toughness of the composite with zirconia remains relatively constant from ambient to 600°C but then decreases rapidly. The mechanism for the toughness enhancement as well as the reason for its variation with temperature are explained using changes in residual stress state as deduced using the sphere in shell model from the measured thermal expansion behavior.     

Strengthening of Porous Mullite and Zirconia CMC Matrices by Evaporation/Condensation

A processing method using evaporation/condensation sintering in an HCl atmosphere was developed for strengthening porous materials without shrinkage. Strengthening without shrinkage is useful in preventing voids and cracks that might be formed during constrained densification, e.g., a porous matrix in a continuous fiber reinforced ceramic composite. Mixtures of mullite and zirconia (monoclinic, tetragonal (3 mol% Y₂O₃), and cubic (8 mol% Y₂O₃)) were studied and exposed to HCl vapor at temperatures up to 1300°C. It was observed that the evaporation–condensation mass transport process produced a porous material with minimal shrinkage. As the crystal structure of the starting tetragonal and cubic zirconia powders did not change after extensive coarsening, it appeared that zirconium and yttrium were transported in the same proportion via evaporation/condensation. The process produced significant coarsening of the zirconia grains, which made the material resistant to densification when heated to 1200°C in air. Because the sintering produced coarsening without shrinkage, the pores also coarsened and a porous microstructure was retained. Mixtures of mullite and zirconia were used because mullite does not densify under the processing conditions used here, namely, heat treatments up to 1300°C. The mullite particles acted as a non-densifying second phase to further inhibit shrinkage when the mullite/zirconia composite was heated up to 1200°C in air. The coarsened cubic zirconia plus mullite mixture had the least densification after heat treatments in air of 100 h at 1200°C.     

Effect of zirconia content on mechanical and thermal properties of mullite–zirconia composite

Abstract

Mullite–zirconia composites were prepared by adding various zirconia contents in the mullite ranging from 0 to 30 wt-% and sintering at 1400–1600°C for 2 h. The phase composition examined by X-ray diffraction showed that mullite was the major phase combined with developed t-ZrO₂ and m-ZrO₂ phase as a function of zirconia content, especially at 1600°C, wherein m-ZrO₂ predominated. Density increased when the zirconia content and sintering temperature were increased ranging from 2·2 to 3·53 g cm^?3. The morphology of mullite grain showed elongated grains, whereas dispersed zirconia showed equiaxed and intergranular grains. Flexural strength was continuously improved by adding zirconia during the sintering temperature ranging from 1400 to 1500°C, whereas flexural strength was initially improved up to 5 wt-% of zirconia addition and deteriorated with more than 5 wt-% of zirconia content during sintering between 1550 and 1600°C. The maximum strength, 190 MPa, was obtained when sintering mullite with 30 wt-% of zirconia content at 1500°C. The degradation of strength at high sintering temperature may be a result from more occurrence of m-ZrO₂ phase. Thermal expansion of sintered specimens indicated linear change and hysteresis loop change. The hysteresis loop obtained with increased zirconia content resulted in the t–m phase transformation. Martensitic start temperature M_s was determined to be 530°C for 15 wt-% zirconia sintered at 1500°C, implying that the t–m phase transformation occurred.     

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。     

Directionally solidified eutectic and off-eutectic mullite–zirconia fibres

Eutectic and off-eutectic mullite–zirconia fibres were grown by LFZ (laser floating zone) directional solidification. The microstructure of the mullite–zirconia eutectic fibres varies from planar coupled eutectic (1 mm/h pulling rate) through mullite columnar growth with coarse zirconia inclusions (10 mm/h pulling rate) to faceted mullite eutectic dendrites, which enclose a dispersion of fine zirconia fibrils (100–500 mm/h pulling rates). Near-equilibrium conditions determine the crystallization of monoclinic zirconia and the absence of any amorphous phase, whereas for higher speeds the tetragonal structure is retained and a residual liquid is kept after the eutectic solidification. Similar structural and morphological characteristics are displayed by the mullite-rich off-eutectic composition added to the development of prismatic crystals of mullite primary phase. In opposition, heavy constitutional supercooling takes place in the case of the zirconia-rich off-eutectic fibres, where equiaxed zirconia dendrites soon form as a primary phase, leaving a non-equilibrium mixture of alumina and sillimanite as interdendritic constituent.