Triaxial Whiteware Compositions

When the ceramic contains more than one phase, each phase will have different thermal expansion coefficients. On heating and cooling, this difference can give rise to thermal stresses at the phase boundaries. These stresses can cause internal cracks. Such a crack is seen in the microstructure of a triaxial whiteware composition, shown in Figure 6.13. 

Microstructure of a triaxial whiteware composition. (From W. D. Kingery et al.. Introduction to Ceramics, 2nd Edn., John Wiley, 1976, pp. 783-812.)... 

Earthenware refers to products produced from unbeneficiated clays with no other additives. Earthenware clays are formed by incomplete conversion of the parent mineral formation and they contain substantial amounts of residual feldspar and quartz, giving a composition similar to a triaxial whiteware [3], Earthenware bodies are typically formed by throwing or modeling [22], Earthenwares are self-fluxing during firing due to the alkali content. Fired earthenware bodies typically have high absorption (10-15%) and are fired at moderate temperatures (cone 5-6) [22], Fired earthenware bodies are usually red and find use as decorative objects, as tiles, or as tableware [26],... 

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