Glass-ceramics nucleation

The processes in question are thus of a highly complex nature. A comprehensive mathematical theory describing all the diflFerent processes does not yet exist. As a result, with todays standard of knowledge concerning the development of glass-ceramics, nucleation is assumed to be influenced by two neral factors ... 

Submicrostmcture of Li20-Al203-Si02 glass—ceramic nucleated with TiOj—approximately 80% crystalline. Small rutile crystals shown in larger crystals of P-spodumene. 

The development of the principles of nucleation and growth eady in the twentieth century (2) ultimately led to the discovery that certain nucleating agents can induce a glass to crystallize with a fine-grained, highly uniform microstmcture that offers unique physical properties (3). The first commercial glass-ceramic products were missile nose cones and cookware. 

A typical heat treatment cycle, as illustrated in Figure 1, comprises both nucleation and crystallization temperature holds, but some glass-ceramics are designed to nucleate and/or crystallize during the ramp itself, eliminating the need for multiple holds. 

Stookey, S.D. (1961) Controlled nucleation and crystallization leads to versatile new glass-ceramics, Chem. Eng. News 39/25, 116. 

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