Rapidly fired porcelain

Conventional porcelain types require tunnel kiln transit times of 24 to 72 h. Firing times of 1 to 3 h are attainable with the recently developed rapidly fired porcelains. With such short firing times the furnace throughput can be kept high even when the articles are mounted as a single layer 

Newly developed rapidly fired porcelains only require fire times of ca. 3 h 

The batches for rapidly fired porcelains must be adapted to the short firing times 

The batches for rapidly fired porcelains have to be adapted to the short firing times to obtain product properties comparable with those of conventionally fired porcelains, despite the diffusion-controlled slow chemical reactions. Suitable mixtures contain lower concentrations of quartz and fluxes and contain prefired raw materials such as calcined kaolin (fireclay). Satisfactory tran.sparency can be obtained by using very Fine particulate quartz sorts, which dissolve sufficiently rapidly in the glass phase. 

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Hard porcelain finds chemical and electrotechnical applications, as well as in tableware, etc. Soft porcelain is used in the manufacture of decorative ware and tableware. Old Asian porcelains also belong to the soft types. One special type of porcelain contains Li20 and can be fired below 1200 °C. The firing temperature is also reduced by divalent oxides — hence the presence of CaC03 in the formulae. Such measures also narrow the sintering interval, since the melts arising show a steeper viscosity curve and their content increases rapidly with increasing temperature. 

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