Aqueous slip casting of complex-shaped ceramic components

Results of theoretical and experimental studies of the process of aqueous slip casting of complex-shaped ceramic components using plaster molds are given. A technology for manufacture of complex-shaped homogeneous high-quality preforms from quartz ceramics such as aerial fairing shells is proposed. __________ Translated from Novye Ogneupory, No. 6, pp. 25–32, June, 2006.     

Potentiality of the Electrophoretic Deposition Method for Molding Components from Lithium Alumina-Silicate Glass Slips

The potential use of an electrophoretic deposition method for molding preforms from a lithium alumina-silicate slip is demonstrated. The time needed to mold preforms 20 mm thick does not exceed 100 min, and their physicomechanical properties (density, porosity of green and sintered materials, mechanical strength) compare well with those of preforms obtained by the traditional ceramic technology. Slips of finely dispersed grain composition can also be used to prepare glass ceramic parts with improved physicomechanical properties.     

Structure evolution in thermoplastic slips based on aluminum nitride

Conclusions The content of the free and the fixed dispersing medium and the limiting concentration of the solid phase in the thermoplastic slips used for hot pressure casting of aluminum nitride preforms are close to the values of the corresponding parameters of the aqueous dispersions of the ceramic oxide materials. When selecting the composition of the thermoplastic binders, the maximum value of the critical content of the solid phase forms the controlling factor. Other things being equal, the plastic viscosity depends on the degree of filling-up of the system and the volume fraction of the kinetically free dispersing medium; the density of the preforms and their shrinkage during the firing process are determined by the volume fraction of the solid phase in the slip and the volume fractions of the kinetically free dispersing medium.Translated from Ogneupory, No. 3, pp. 11–14, March, 1993.     

Improving the slip-casting technology for ceramic articles

Ways of optimizing the technology for ceramic articles based on the method of slip casting under the effect of capillary forces in porous molds under pressure are considered. The technology for preparing fired molds with channels for slip casting under pressure is presented.Translated from Steklo i Keramika, No. 12, pp. 15–17, December, 1995.     

Improving the design and technology of molds for ceramic articles

Ways of improving the design and the manufacturing technology of porous and poreless molds for shaping ceramic articles by the methods of slip casting and plastic molding are considered. New techniques for the production of porous molds are suggested, which make it possible to decrease the cost of the molds and optimize the processes of slip casting and plastic molding of ceramic articles.     

An Electrophoretic Deposition Method for Molding Components from Slips of Inorganic Materials

Studies have been conducted showing that, for molding components from aqueous slips, the traditional casting technology based on the use of plaster molds can be replaced by a new technique of electrophoretic deposition. The new technique, using copper plates for both anode and cathode, saves processing time significantly (by several tens) and improves the quality of molded preforms.     

Influence of glass phase on Al2O3 fiber-reinforced Al2O3 composites processed by slip casting

The present work describes the processing of alumina fiber reinforced alumina ceramic preforms consisting of chopped Al₂O₃ fibers (33 wt%) and Al₂O₃ (67 wt%) fine powders by slip casting. The preforms were pre-sintered in air at 1100 °C for 1 h. A lanthanum based glass was infiltrated into these preforms at 1250 °C for 90 min. Linear shrinkage (%) was studied before and after glass infiltration. Pre-sintered and infiltrated specimens were characterized by scanning electron microscopy, energy dispersive X-ray, X-ray diffraction, porosimetry and flexural strength. The alumina preforms showed a narrow pore size distribution with an average pore size of ∼50 nm. It was observed that introducing Al₂O₃ fibers into Al₂O₃ particulate matrix produced warp free preforms with minor shrinkage during pre-sintering and glass infiltration. It was observed that the infiltration process fills up the pores and considerably improves the strength and reliability of alumina preform.     

Magnetic slip casting for dense and textured ceramics: A review of current achievements and issues

Ceramic materials are ubiquitous in technologies operating under high mechanical, thermal or chemical constrains. Research in ceramic processing aims at creating ceramics with properties that are still challenging to obtain, such as toughness, transparency, conductivity, among others. Magnetic slip casting is a process where an external magnetic field is used to createcontrolled texture in ceramics. Over the past 20 years of research on magnetic slip casting, dense and textured ceramics of multiple chemistry were found to exhibit enhanced properties. This paper reviews the progress in the field of magnetic slip casting, details the processing parameters and the textures obtained for a diverse range of compositions. The structural and functional properties of the magnetically textured slip casted and sintered ceramics are presented. This overview of the magnetic slip casting process allows to identify critical directions for future advancement in advanced technical ceramics.     

卫生陶瓷压力注浆成型的泥浆性能研究

研究了卫生陶瓷压力注浆成型的泥浆性能，通过一系列试验，讨论了泥浆性能对压力注浆成型的影响。     

THE CASTING OF CLAY WARE—A RÉSUMÉ*

Considerable difficulty has been encountered in developing methods suitable for determining the properties of a casting slip that in turn define the casting quality of the slip. A survey of the literature is made, especially that dealing with the colloidal phenomena of clay suspensions, which might be of assistance in solving some of the problems encountered in the use of the casting process. The term, casting quality of slip, is detined and the factors which influence this property are considered in detail. Control methods proposed by various investigators are discussed critically. A new method of slip control is suggested. The sources and remedies of some troubles encountered in the casting process are discussed.     

SOME OBSERVATIONS IN THE CASTING OF HEAVY ELECTRICAL PORCELAINS1

A summary is given of experiences had in the manufacture of heavy and intricate electrical porcelains by the casting process. Some of the subjects discussed are selec- tion and test of clays, mixing of casting slip and its control, and several details of the methods used in casting the ware. Special emphasis is placed on the limits established for viscosity and specific gravity of the casting slip and the general proposition that the slip must be within the limits set for viscosity regardless of specific gravity.     

钛酸铝陶瓷涡壳制备工艺的研究

以工业氧化铝和钛白粉为主要原料制备陶瓷泥浆，通过改善泥浆性能，完善注浆成形工艺，对石膏模表面预处理，生坯加工，采用特定的装烧方式和冷加工方法研制出了陶瓷复合涡壳。     

陶瓷注浆成形用偏硅酸钠的生产

本叙述了陶瓷泥浆成形用五水偏硅酸钠制造工艺和影响因素，简要介绍了其在陶瓷行业中的应用。     

The transformation mechanism from suspension to green body and the development of colloidal forming

Colloidal forming is a novel wet-processing way to prepare complex shaped ceramic parts with high reliability at low cost. In this article, the transformation mechanisms from suspension to green body and the development of colloidal forming are reviewed. The transformation from suspension to green body in colloidal forming is mainly dependent on the characteristics of suspension, and solidification is the key link in colloidal forming. Various colloidal forming methods are developed to produce ceramic parts, and these methods include slip casting, tape casting, direct coagulation casting, injection molding, gel-casting and so on. The study of defects during colloidal forming should be focused on the defects formation, inheritance and evolution during drying, de-binding and sintering processes. External free controllable technology of colloidal forming is an effective way to achieve ceramic fabrication industrialization, and stress-free colloidal forming is important for the future development of ceramic fabrication.     

卫生陶瓷中、高压注浆成坯速率的研究

卫生陶瓷中、高压注浆成形工艺是当今世界卫生陶瓷成形的最新工艺。本文运用某卫生瓷厂实际大生产中所用的配方和原料，通过试验设计，运用回归分析技术研究了泥浆的触变性及泥浆组分的颗粒级配对中、高压浇注成形的成坯速率的影响。     

高密度陶瓷颗粒注浆成形技术理论与实践

简述了陶瓷颗粒注浆成形工艺的技术特点，并结合工程研究实践，分析和探讨了与颗粒浇注泥浆的颗粒粒度组成、颗粒沉降特性、外加剂的选用和泥浆的流变特笥等因素相关的技术理论以及这些因素对注浆工艺和坯体质量的影响。     

Effect of medium condition change on green body density during casting and drying

The present study examined whether the optimum slurry conditions in which the green body with the highest packing fraction was fabricated were the same regardless of whether tape or slip casting methods were used. Additionally, we investigated the optimum slurry evaluation method to predict the packing fraction of each green body. Specifically, aqueous dense alumina slurries, whose particle dispersion state was changed by varying pH and the amount of dispersant additive, were prepared. After changing the pH, the optimum slurry conditions were achieved regardless of the casting method. The most suitable amount of additive dispersant differed due to the changing solution conditions during the casting and drying process; the medium of the slurry permeated into the plaster during slip casting and dried on the substrate during tape casting. Thus, in slip casting, non-adsorbed polymers could also be permeated. Hence, it is crucial for slurry evaluation to predict the packing fraction of the slip cast body. A sedimentation test, which involved particle condensation as well as casting, was valid for the green sheet. Conversely, it was experimentally shown that the constant pressure filtration test, which involved the permeation of the medium in addition to particle condensation, was suitable for slip casting.     

The slip casting rate for quartz ceramics

Conclusions In an investigation of the influence of the principal factors on the rate of slip casting quartz ceramics it was established that the density (porosity) of the deposited cast body is the main determining factor in the casting rate. The density of the body depends on the degree of stabilization, the pH, and the granularity of the slip suspension, and on the use of vibration. The casting rate may vary tenfold with the porosity of the casting. The factors which increase the density of the casting reduce the casting rate to the same extent, and vice versa.The casting rate is influenced, moreover, also by the water/plaster ratio of the mold and by the moisture content (density) of the slip suspension.Translated from Ogneupory, No. 8, pp. 48–52, August, 1973.     

Enhanced casting rate by dynamic heating during slip casting

The slip casting process is widely used to consolidate ceramic particles from aqueous suspensions to form green compacts, particularly those with complicated shapes. Raising the slip temperature during slip casting is known to increase the casting rate, this is believed to be via a decrease in water viscosity. However, differences have been observed when using convection and microwave heating to raise the temperature. In the present work, it has been found that the use of short-pulses of microwave energy to heat the casting system dynamically causes a greater degree of acceleration than when using conventional radiant heating. The increased uptake of water from the slip by the porous mould is believed to be indicative of a vaporisation–condensation cycle mechanism. A negative pressure would be created during the condensation stage of the cycle, acting as an additional suction force to the capillary action and hence accelerating the casting process.