论中国陶瓷生产技术工艺的发展超向和对国产全自动粉料压力成形机的若干见解

颗粒状粉料压力成形工艺技术是现代陶瓷生产中成形方法的发展方向,尤其是行业的传统产品,如墙地砖、大部分的日用瓷、电瓷、特瓷等。国产压砖机技术已经相当成熟,再进行一些完善,可以走向国内国外两个市场,并具有很好的竞争力。     

预渗入法衬瓷层中氧化锆分布规律

针对表面涂层技术工艺复杂,容易剥落等问题,提出了预渗入法制备陶瓷涂层技术。即预先将坯体造孔,再用纳米陶瓷粉与合金粉通过特殊方式合成制成复合粉,将该复合粉涂于有孔坯体的表面,使粉料进入孔洞中;在气氛保护条件下烧结,使复合粉与基体材料同时烧结并形成冶金结合界面,有效提高了表面性能。利用扫描电镜观察了衬瓷层的显微组织,分析了纳米氧化锆陶瓷成分在衬瓷层中的分布规律;发现ZrO2含量为20%-40%时均可得到较为理想的衬瓷层;氧化锆陶瓷相从表面向基体呈递减趋势;决定衬瓷层的厚度的最重要原因是直孔洞的深度。     

Identification of quality parameters for barium titanate powder

The authors describe the results of developing methods for determining some quality parameters of barium titanate powder, which is the main component in some ceramics that are used to produce capacitors. The degree of transformation of ZnO and BaTiO₃, the volume density of sintered powder, the degree of its dissolution in hydrochloric acid, and some diffraction characteristics of BaTiO₃ powders are determined according to the developed methods and can predict with a sufficient degree of reliability the quality of ceramic capacitors made from barium titanate powders.     

控制大气污染用的蜂窝陶瓷材料

本文介绍了用作大气污染控制和化工反应中蜂窝陶瓷材料的各种具体要求和所取得的显著进展。多孔蜂窝陶瓷的几何表面大，压力降小，扩散距离短，反应器体积小，是优良的催化剂载体，已广泛用于汽车废气排放处理，烟道气去除ＮＯｘ的催化还原过程和燃气轮机等的催化助热燃烧，以及共他化学反应过程，在这些领域发挥了独特的作用。     

化学镀镍及其前处理对空心陶瓷粉体润湿性的影响

给出了一种空心陶瓷粉体表面化学镀及其前处理工艺,采用透过高度法、红外光谱法对前处理和化学镀后粉体表面性能及在不同润湿相中的润湿性能进行了研究。实验结果表明:空心陶瓷粉体经粗化、化学镀处理后润湿性能有大幅提高,利于提高粉体与基体的结合强度;利用润湿性的变化可以考察其粗化处理程度。     

含钾砂页岩除铁提质及陶瓷应用试验研究

分析了含钾砂页岩中铁的赋存状态,开展含钾岩石除铁提质试验,并对除铁粉料应用于陶瓷原料进行试验研究。结果表明,采用磁选-酸浸工艺,在磨矿细度为-74 μm占50%(质量分数),磁场强度为190 mT,盐酸浓度为20%(质量分数),浸出温度为90 ℃的最佳条件下,除铁粉料中全铁含量可降低为0.13%(质量分数),K₂O和Na₂O总含量提高至11.00%(质量分数),含量符合陶瓷用钾长石Ⅰ级品要求。除铁粉料在陶瓷胚体成型试验中易于成型,烧成温度范围宽,成品率高,可替代长石作为陶瓷原料使用,开拓了含钾砂页岩作为陶瓷原料使用的新方向。     

防弹装甲用碳化硼陶瓷材料的研究进展

碳化硼陶瓷具有较低的密度、仅次于氮化硼和金刚石的硬度以及优异的耐腐蚀性能,满足防弹材料要求的高强度、高耐磨、高硬度、低密度,简称为"三高一低",当前已经应用于高端装备的防护系统中。然而,碳化硼陶瓷为强共价化合物,且具有低的扩散系数,导致其在制备过程中的主要问题是烧结致密化问题和脆性问题。因此,许多的研究工作集中在碳化硼陶瓷的烧结技术、烧结助剂以及对碳化硼陶瓷进行增韧。本文聚焦防弹装甲用碳化硼陶瓷,首先从碳化硼的晶形结构和相图,综述了碳化硼陶瓷粉体的制备技术以及碳化硼陶瓷的烧结工艺,阐述了改善碳化硼断裂韧性较低的方法,最后分析了碳化硼陶瓷防弹材料的研究现状,并且展望陶瓷防弹装甲的未来研究方向。     

Friction behavior of PTFE-coated Si3N4/TiC ceramics fabricated by spray technique under dry friction

PTFE coatings were deposited on the Si₃N₄/TiC ceramic substrate by using spray technology. The surface and cross-section micrographs, adhesive force of coatings with substrate, surface roughness and micro-hardness of the coated ceramics were examined. The friction and wear behaviors of ceramic samples with and without coatings were investigated through carrying out dry sliding friction tests against WC/Co ball. The test results indicated that the coated ceramics exhibited rougher surface and lower micro-hardness, and the PTFE coatings can significantly reduce the surface friction and adhesive wear of ceramics. The friction performance of PTFE-coated sample was affected by applied load due to the lower surface hardness and shear strength of coatings, and the main wear failure mechanisms were abrasion wear, coating delamination and flaking. It can be considered that deposition of PTFE coatings is a promising approach to improve the friction and wear behavior of ceramic substrate.     

金属表面热化学反应法陶瓷涂层研究现状及工艺名称商榷

介绍了近几年新出现的热化学反应法陶瓷涂层技术,并将国内热化学反应法研究现状作了综述.依据该陶瓷涂层技术的反应实质,本文认为应称为"低温固相反应法陶瓷涂层技术".     

Effect of Powder Surface Modifications on the Properties of Silicon Nitride Ceramics

The effect of surface oxygen concentration of silicon nitride powders on the properties of resulting ceramics was studied. A high-purity silicon nitride powder was treated physically and chemically to modify its surface oxygen content. The resulting powders were hot-pressed into dense ceramics using 6 wt% yttria as a sintering aid. Strength and oxidation resistance of these ceramics were measured and correlated with the powder and ceramic compositions as well as the resulting intergranular phases. Results show that the phases developed in yttria-containing silicon nitride ceramics vary with slight changes in the initial powder oxygen content, as predicted, and that strength can be correlated to initial oxygen concentration. The mechanical strength vs oxygen content curve has a definite maximum; i.e., there is a small oxygen concentration range at which optimum ceramic strength is realized. Best results are obtained when the oxygen content is increased by thermal oxidation; other techniques such as chemical oxidation or addition of silica are not as effective, particularly in attaining high strength at elevated temperatures.     

Nickel ion removal by porous potassium magnesium titanate made from plate-like crystals

Plate-like potassium magnesium titanate (KMTO) powder prepared by molten salt growth method and the KMTO porous ceramic synthesised by polymeric sponge replication method were used as sorbents to remove nickel ions from wastewater. Both powder and porous ceramic were characterised by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The maximum adsorption capacities of powder and porous ceramic were 96 and 24?mg?g^??1 respectively at a pH value of 6 (25°C). However, the removal efficiencies of both could reach up to 99%. Moreover, the adsorption kinetics for the KMTO powder and the porous ceramics followed the pseudo-second-order kinetic model, and the equilibrium data for the KMTO powder fitted the Langmuir isothermal model well, while the porous ceramics fitted with the Freundlich model. The mechanism of the adsorption by the KMTO powder and the porous ceramic was ion exchange. It was also shown that the nickel saturated KMTO powder and the porous ceramics were stable in leaching tests.     

Mechanics of penetration of ceramic targets

A model for the penetration of a ceramic target with the formation of an expanding conical hole is proposed that can be used to determine the apex angle of the cone knocked out from the target. The main cause of this fracture of ceramic targets is that the tensile strength of a ceramic material is much lower than its compressive strength. A method for calculating the maximum penetration velocity in a ceramic target without substrate was developed using the energy fracture criterion for ceramics. Two-dimensional numerical simulation of the impact of a steel projectile on a corundum plate showed satisfactory agreement between the calculated and experimental configurations of the resulting conical crack provided that the ratio between the compressive and tensile strengths corresponds to the recommendations of the developed model.     

低温烧结SiC-Al2O3-Y2O3复相陶瓷的研究

以SiC微粉为主要原料，添加适量氧化物复合烧结助剂在相对低的温度下烧结制成性能优良的精细SiC复相陶瓷材料，能满足耐磨陶瓷部件、机械密封件的使用要求，生产成本低，具有较强的实用价值。     

Injection molding of surface modified powders with high solid loadings: A case for fabrication of translucent alumina ceramics

Solid loading is a critical key to the fabrication of ceramic compacts with high densities via ceramic injection molding. As reported in most previous work, solid loading of ultra-fine alumina feedstock system could be achieved only up to ∼58 vol% with stearic acid (SA) as the surface modification agent. In present work, different from the traditional work in which SA has been introduced just in the powder blending process, we have successfully prepared the feedstock with a much higher solid loading up to ∼64 vol% by a prior ball milling treatment of ceramic powders with a small amount of SA before the traditional blending process. It can be attributed to that SA can be coated homogeneously around the powder surfaces by a chemical reaction induced by ball milling treatment. Highly translucent Al₂O₃ ceramics have been fabricated, which suggests an alternative route for fabrication of translucent ceramics with high quality.     

Sliding-Wear-Resistant Liquid-Phase-Sintered SiC Processed Using α-SiC Starting Powders

Low-cost α-silicon carbide (SiC) starting powder, instead of the more expensive β-SiC starting powder, has been used to process liquid-phase-sintered (LPS) SiC ceramics with different microstructures: (i) elongated SiC grains ( in situ toughened LPS SiC), (ii) fine equiaxed SiC grains, and (iii) coarse equiaxed SiC grains. The effects of microstructure on the sliding-wear properties of these LPS SiC ceramics have been studied. The sliding-wear resistance of the in situ toughened LPS SiC ceramic is found to be significantly better than that of two equiaxed-grain LPS SiC ceramics. This has been attributed to the existence of a hard, interlocking network of elongated SiC grains and the isolated nature of the yttrium aluminum garnet (YAG) second phase in the in situ toughened LPS SiC ceramic. This is in contrast to the equiaxed-grain LPS SiC ceramics, where the equiaxed grains are embedded within a continuous YAG phase matrix. The use of the α-SiC starting powder allows the processing of low-cost LPS SiC ceramics that are both sliding-wear resistant and tough.     

微波干燥技术在蜂窝陶瓷中的应用

蜂窝陶瓷挤压成形后的强度低、难干燥等问题．严重制约了蜂窝陶瓷的广泛应用。近年来,微波干燥技术已应用于蜂窝陶瓷上,可以解决其强度低、难干燥等问题。结果表明,微波干燥技术能降低成形后蜂窝陶瓷坯体约10％的水分。通过分析蜂窝陶瓷干燥的过程,提出了热风干燥与微波干燥相组合的方法,结合两者的优势,以达到优化节能的目的。     

Embedded Capacitor Technology Using Aerosol Deposition

Embedded passives, which achieve miniaturization, cost reduction, and higher performance, are regarded as one of the most promising technologies for a future RF module substrate. Currently, a BaTiO₃/Polymer composite is being used for the embedded capacitors in printed wiring boards. One of the drawbacks of this composite is its relatively low dielectric constant, because the polymer component with a low dielectric constant suppresses the dielectric constant of the whole composite. We propose a resin build-up circuit board with passive functions embedded in a ceramic film without any polymer component for the next-generation low-cost RF modules. We have already manufactured a prototype board with ceramic capacitors embedded in an FR-4 substrate using a unique ceramic deposition technology: aerosol deposition (ASD) in which many kinds of ceramics can be deposited on a substrate at room temperature by making use of accelerated ceramic nanoparticle aerosol bombardment with a nozzle. In this study, first we examine the effects of the characteristics of raw ceramic powder on the crystal structure and the dielectric properties of ASD films. As a result, we confirmed that dense BaTiO₃ dielectric films can be deposited when raw powder without strain is used. From the resulting polarization versus electrical field (P–E curve), we confirmed that paraelectric was observed in the dense films, while the porous BaTiO₃ films deposited using milled powder exhibit a small hysteresis loop. We also clarified that dense BaTiO₃ dielectric films exhibit a nanostructure with a texture consisting of particles under 10 nm in diameter. We also examine the interfacial behavior between BaTiO₃ dielectric films and the Cu electrode, in order to investigate the deposition temperature and the reliability of a BaTiO₃ ASD film under high temperature (250°C), high humidity (100 Rh%), thermal cycle condition (−55°C to 150°C), and bias DC voltage (5 V). We clarified that the BaTiO₃ ASD film satisfies the criteria of reliability in the microelectronic packaging area.     

Aerosol deposition of alumina films on microstructured silicon substrates

Aerosol deposition (AD) is a room-temperature ceramic coating method, which has been used for many applications. Various substrates, such as metals and ceramics, have been used depending on the application, but it is not clear how the substrate microstructure affects the deposition processes and film quality. In this study, AD alumina films deposited on silicon substrates with microstructures consisting of line and space patterns were systematically investigated. The films were formed along the microstructure on the substrate when the linewidth was much larger than the grain size of the raw powder. Conversely, on narrow-linewidth substrates, the films were supported by the lines and the spaces were sealed. The effect of the substrate microstructure was analyzed in terms of the residual stress of the films.     

Certain Specifics of Quasi-Isostatic Molding (A Review)

The author considers specifics of the method of quasi-isostatic molding, which is the most perfect, economical, and simple method for molding products from powder materials providing for a high quality of products due to the volume compression of the molding material. The method can be used for molding articles from ceramic, metal, and graphite powders, glass ceramics, ferrite, abrasive materials, and in production of refractory articles.     

Effect of powder treatment on injection moulded zirconia ceramics

Agglomerated fine zirconia powder was exposed to dry and wet ball milling and to wet mixing. The subject of study was the effect of powder treatment on the disintegration of agglomerated particles, on the rheological properties of thermoplastic ceramic mixtures, and on the properties of sintered yttria-stabilized tetragonal zirconia polytrystalline ceramics (Y-TZP). Test specimens in the shape of bars and discs were produced by injection moulding of ceramic mixtures containing 52.5 and 49 vol% of powder. The powder treatment was found to yield improved rheological properties of ceramic mixtures and improved mechanical properties of sintered specimens in the case of 52.5 vol% of powder in the ceramic mixture. However, the same or even better mechanical properties of sintered components were found when the loading of ceramic mixture was reduced to 49 vol% of powder and non-treated powder was used.