Ceramic Processing Method

Ceramic processing occurs through some sequential activities, which starts with raw materials, proceeds through batch preparation and forming and concludes with firing. The sequence of steps is illustrated by Fig. 8.7. Ceramics are formed from raw materials used for traditional ceramics which are different from those used for advanced ceramics. For traditional ceramics raw materials consist of silica, clay, fluxes and are refractory materials. Silica is obtained either from massive quartz deposit or pure quartz sands. The quartz is washed and groimd. The most commonly used clay minerals are kaolin and talc. China clay is predominantly kaolin. Ball clays are finer particle size elays that contain 

Wide ranges of forming processes are used. Extrusion, dry processes and injection moulding are three processes that are widely used in polymer, metal and food technologies and therefore familiar to maximmn engineers. Both slip 

Forming process Production value Component shape Component size 

Tape casting Thin sheets Simple High 

Slip casting method It is a fabrication method. In this process low-viscosity slurry of ceramic powder is poured into a porous plaster mould. The porous nature of the plaster mould draws water fix)m the slurry that eontacts the mould. This process continues as the capillary section of the mould continues to draw water through the increased ceramic solids at the mould wall. After establishing a sufficiently thick wall at the mould wall, the remaining liquid is drained, dried and when the cast is sufficiently dried, the mould is removed. 

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The production of BeO ceramics is generally by classical ceramic processing methods described in 17.2. Pores hinder thermal conductivity, however, and to maximize this property, porosity must be reduced. 

Sro. 95Yb(3 05CeO3 x Ceramic Samples Produced Using Differing Ceramic Processing Methods... 

The grinding process often results in surface fracture damage nullifying the benefits of advanced ceramic processing methods (Bandyopadhyay and Ohmori, 1999). These defects can significantly reduce the strength and reliability of the finished component and are sensitive to grinding parameters. 

The purpose of this task Is to determine and develop the reliability of selected advanced ceramic processing methods. This task Is to be conducted on a scale that will permit the potential for fmanufacturlng use of candidate processes to be evaluated. 

Although polymer precursors to non-oxide ceramics offer considerable potential for processing a wide variety of novel shapes, at quite low temperatures with respect to standard ceramics processing methods, very few commercial products based on this approach have been forthcoming [1-5]. Furthermore, very few polymer derived non-oxide ceramics exhibit properties commensurate with those found for the same ceramics produced by high temperature methods. 

High surface areas and small pore sizes characteristic of inorganic gels are properties unattainable by conventional ceramic processing methods. These unique properties may be exploited in applications such as filtration, separations, catalysis, and chromatography. (See Table 12.) The use of porous gels in separations and nitrations was reviewed by Klein [243]. 

Preceramic polymers have the potential to improve traditional ceramic processing methods (2). In particular, ceramic injection molding may be enhanced by the replacement of organic binders with thermosetting polysilazanes. Table II compares the attributes of the two binder systems. 

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