Ceramization process

The elementary processes, which determine the properties of the glass ceramic following the primary annealing of the base glass and quality control, are nucleation and crystallization. The characteristic T t function which defines these processes is pictured in Fig. 3.31, see Sect. 3.3.5. 

However, the actual temperature program of the ceramization process is a complex function of time and temperature rather than a simple two-step process, because one has to take into account the changes in transmission, viscosity, density, and GTE during the crystallization. 

To get transparent tinted or colorless glass ceramics one has to avoid strong scattering from the crystal sites. The scattering intensity scales with 

The crystallization process itself is an exothermic reaction (on the order of 0.1 J/kg) and accompanied by a strong increase in viscosity (3 4 orders of magnitude). Moreover, the density increases by about 3% and the CTE changes from 4 x 10 to near zero as shown in Fig. 3.42. During the 

The decoration of cooktop panels is often performed at the same time as their ceramization. In this case the temperature-dependent properties of glazes have to be matched to the ceramization process as well. 

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R. J. Pugh, Dispersion and Stability of Ceramic Powders, in Surface and Colloid Chemistry in Advanced Ceramics Processing, Marcel Dekker, New York, 1994, Chapter 4. 

Another approach is to use the LB film as a template to limit the size of growing colloids such as the Q-state semiconductors that have applications in nonlinear optical devices. Furlong and co-workers have successfully synthesized CdSe [186] and CdS [187] nanoparticles (<5 nm in radius) in Cd arachidate LB films. Finally, as a low-temperature ceramic process, LB films can be converted to oxide layers by UV and ozone treatment examples are polydimethylsiloxane films to make SiO [188] and Cd arachidate to make CdOjt [189]. 

The chemical potential of a curved surface is extremely critical in ceramic processing. It detemiines reactivity, tlie solubility of a solid in a liquid, tire rate of liquid evaporation from solid surfaces, and material transport during sintering. 

This chapter will describe some of tire basic unit processes in ceramic manufacturing, and will touch on tire pertinence of tire physical chemistry of surfaces in selected unit processes. For a more comprehensive review of ceramics and ceramic processing, tire reader is referred to otlrer sources [3, 4 and 5]. 

Reed J S 1995 Introduction to the Principals of Ceramic Processing 2nd edn (New York Wiley) pp 18-27 Reed J S 1995 Introduction to the Principals of Ceramic Processing 2nd edn (New York Wiley)... 

Somasundaran P 1978 Theories of grinding Ceramic Processing Before Firing ed G Y Onoda Jr and L Hench (New York Wiiey) pp 105-23... 

Ewsuk K G 1993 Ceramics (processing) Kirk-Othmer Encyciopedia of Chemicai Technoiogy 4Vn edn, voi 5 (New York Wiiey) pp 607-10... 

Shanefieid D J 1996 Organic Additives and Ceramic Processing with Appiications in Powder Metaiiurgy, ink, and Paint 2nd edn (Boston, MA Kiuwer)... 

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