Non-equilibrium microstructure of bone china

Abstract

saturate the clay with CaO, with the result that little of the b-TCP needs to break down and form low melting phases. Commercial bone china microstructures are far fromThe b-TCP crystals, which now act as a filler, confer equilibrium consisting of distinct regions of lath-like refractoriness on the body. The proportions of clay, flux, (0•4-10 mm) anorthite and spheroidal (1-3 mm) and bone may be varied from the typical 25 : 25 : 50 ratio b-tricalcium phosphate (b-T CP) nodules embedded in depending on the properties desired and other components a heterogeneous composition glass along with isolated may be substituted. For example, ball clay and gum arabic irregular (∏30 mm) a-quartz crystals. T he composcan be included in the body recipe to increase green strength ition and morphology of the phases formed on firing and bentonite clay (predominantly montmorillonite) can be suggest that anorthite crystallised in clay relicts by the added as a plasticiser to increase workability and green reaction of metakaolin with CaO, b-T CP crystallised strength.3 f rom decomposition of bone ash, and that the liquidIn the UK bone china is manufactured using the following formed on vitrification has variable composition general processing route. Hard raw materials are crushed depending on the composition of adjacent phases. P 2 O 5 by jaw and roller crushers, weighed, wet ball milled, sieved, was never detected in the glass suggesting that any and passed over magnets to remove metal particles. Clays P 2 O 5 that dissolves in the liquid on firing is transient. (with a particle size of ~0•2-6 mm) are blunged. Bone ash T he cracks sometimes observed in and around b-T CP is milled to a median size of ~3-5 mm and fluxes to clusters arise from thermal expansion mismatch ~10 mm. Weighed proportions of clay, flux, and filler are between b-T CP and the surrounding glass and then mixed in mixing arks, again sieved, and passed over anorthite. BCT /381 magnets and stored. De-watering may be carried out by filter pressing or spray drying. After filter pressing, the T he authors are in the Department of Engineering bodies are aged and passed through a pug mill to de-air Materials, University of SheYeld, Mappin Street, the body and homogenise the water content. Shape forming SheYeld S1 3JD, UK. Manuscript

Sintering of Whiteware Body Depending on Different Fluxing Agents and Binders

“…The reactions of bone ash in porcelain body were studied in detail in Refs. [12,13]. Bone ash-luxing agent for bone porcelains (bone china)-is usually produced by the calcination of bovine bones at the temperature of 1100°C.…”

Investigation of spodumene-bearing rock as a flux for bone china production

“…The level of P 2 O 5 , which may be considered a flux according to previous studies, as proposed in Cooper 10 and Iqbal et al 8,15 , is identical in the both formulations. It can also be considered identical the amount of tricalcium phosphate formed.…”

“…Alkali feldspars which have higher levels of albite (NaAlSi 3 O 8 ) showed vitrification between 1220 °C-1240 °C, in another studies 5,8 . By using conventional flux as alkali feldspar (richer in sodium than the feldspar used in this work) and/or nepheline syenite, it was showed similar firing ranges and in some cases, lower ones 5,14,15 .…”

“…Usually, strong fluxes are difficult to use for bone china production because of the short firing range of this porcelain, limited by low thermal stability of parts 8 . The formation of a glass phase determines the firing temperature of the parts.…”

Novos fundentes para produção da porcelana de ossos

“…Se a queima procede lentamente, em temperaturas pouco acima de 1250 ºC ocorre a deformação das peças [7]. Portanto, a queima deve ser realizada sem se atingir o equilíbrio, formando as conhecidas fases finais desta porcelana que são a anortita, o fosfato tricálcico e um vidro silicoso.…”