Pyroplastic behaviour of two plastic kaolins in a triaxial porcelain body

Bikaner plastic clay and washed Than clay are used as plastic clay component in commercial triaxial porcelain bodies. Five porcelain bodies based on identical unity molecular formulae but containing two plastic kaolins in different proportions were prepared. The effects of interchanging the above two plastic kaolins on pyroplastic, rheological, thermo-mechanical properties, vitrification behaviour and microstructure have been investigated. The washed Than clay was found to be 1.5 times more effective in improving unfired (green) strength. Its favourable effects include better rheology, a lower vitrification temperature and reduced quartz dissolution. But it also renders the bodies prone to high pyroplastic deformation. Bikaner clay maintains high pyroplastic stability and crystalline phases throughout the firing range. The two plastic kaolins can be interchanged in vitreous porcelain compositions without causing significant variations in fired strength, but compositional variations are needed to adjust the changes in plastic and dry properties, rheology, pyroplasticity, firing range and microstructure