Glass-ceramics microstructure design

There are three key variables in the design of a glass-ceramic the glass composition, the glass-ceramic phase assemblage, and the nature of the crystalline microstructure. 

R. E. Loehman, T. J. Headley, Design of high thermal expansion glass-ceramics through microstructural control, in Ceramic Microstructures 86 Role of Interfaces, J. A. Pask and A. G. Evans, eds.. Plenum Press, New York, 1987. 

Brennen, J.J. 1997. Interfacial design and properties of layered BN(+ C) coated Nicalon fiber-reinforced glass-ceramic matrix composites, in Ceramic Microstructures 96. New York Plenum Press. 

J. J. Brennan, Interfacial Design and Properties ofLayered BN(+C) Coated Nicalon Fiber-Reinforced Glass-Ceramic Matrix Composites, in Ceramic Microstructures Control at the Atomic Level, A. P. Tomsia and A. Glaeser eds.. Plenum Press, New York (1998) 705-712. 

The microstructures of the glass-ceramics resemble well-known structures and phenomena in nature, science, technology, and daily life. In some cases, the microstructures that are discussed exhibit ultrafine crystal structures reminiscent of those of nanopowders. To help describe the appearance of certain microstructures, comparisons are made to the structure of a cell, cabbage head, or a house of cards. These examples are addressed in the following sections. The special properties produced by the specific designs will also be discussed in these sections. 

The determination of properties should provide information and some scientific conclusions helpful in further designing and improving glass-ceramics. Based on the results of even preliminary properties, new insight generally suggests changes in the chemical composition or directions in modification of the microstructure. 

The role of continuous-cooling transformation diagrams in the heat treatment and control of microstructure was presented (for iron-carbon alloys) in Chapter 10. We discussed in this chapter how this type of diagram is employed in designing heat treatments to crystallize glass-ceramics. The following concept map represents this relationship for processing these materials. 

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