|Description:||Calcium carbonate decomposition|
NotesCalcite converts to Quicklime on heating. If burned higher or too long it converts to dead burned lime. The decomposition process of this compound can generate tremendous amounts of gases and is quite complex and the subject of much discussion and research. Nilo Tozzi, an expert in tile manufacturing, says that 'calcium carbonate decomposes at about 880C when alone but when mixed into a ceramic body its decomposition starts at about 700C'. While some sources indicate a narrower range than shown here, we feel this wider range recognizes the many factors the play when calcite is found in bodies and glazes in a ceramic kiln (particle surface area, atmosphere, pressure, interactions with surrounding particles, density and thickness of the containing matrix, speed of firing). This material is highly suspect in glaze flaws related to the generation of gases from constituent materials in the glaze recipe. It may be advisable to source CaO from a frit or wollastonite if you have a problem. See the book Thermal Decomposition of Ionic Solids by Andrew K. Galwey, Michael E. Brown.
Out Bound Links
In Bound Links
Calcium Carbonate - CaCO3
Carbonate of Lime, Whiting, Aragonite, Calcite, CaCO3
Quicklime - CaO
Burnt Lime, Dead-burned lime
A wide range of carbonates are used in ceramics and each of these has its own thermal history. Within that is a range where they decompose to give off...
Ceramic bodies and glazes contain materials that release carbon as they decompose on heating. Clays, gums, plasticizers are examples. These can still be burning out at higher temperatures than most people realize (cone 04 or higher). That burning generates gases, if glazes are beginning to melt befo...
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