Ceramics
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Ceramics

Traditional ceramic products include bricks, tiles, pipes, tableware and sanitaryware, as well as the refractory materials used in high temperature applications, including the manufacture of other ceramics. Modern ceramics or technical ceramics include a wide range of non-metallic inorganic compounds which are used in more diverse applications such as disc brakes, body armour, superconductors, cutting tools, medical devices and bearings.
 
At the time of the industrial revolution, Stoke-on-Trent became the centre of the pottery industry in Britain because of access to local sources of clays, salt and lead for making glazes and large coal deposits for fuel. The most common design for firing was the bottle kiln. This was a circular brick kiln with an outer skin and an inner core with a series of fireplaces at the bottom. Flues took the hot gases up through the centre of the kiln. The ware were placed in saggars, boxes of fire clay, piled up in large stacks. These kilns burned tons of coal, wasted a lot of heat and caused extensive pollution but many remained in use until the Clean Air Acts of the mid twentieth century.
 
The first kilns for operating a continuous batch process were invented in the mid nineteenth century. An early design known as the Hoffmann kiln consisted of a set of chambers in a circular or oval layout connected by a central fire passage. One chamber at a time was fired and the combustion gases were used to preheat the next section to be fired. These kilns were used for  brick making but were not suitable for the variety of different shapes and sizes of products made by the tableware manufacturers.
 
Modern kilns are much cleaner and more efficient, offering excellent control over firing times and temperatures as required. For continuous production of large quantities of homogeneous items, such as bricks or tiles, a tunnel kiln is likely to be the best option. In this arrangement, the ware is loaded onto kiln cars which move through the tunnel, heating up as they approach the burners in the central part of the kiln and cooling down afterwards. Kiln cars need to be lightweight and able to withstand the changes in temperature experienced in cycling through the kiln. A shuttle kiln, with cars shuttling back and forth, is more suitable for intermittent firings or frequent changes in the firing cycle as different products are processed.
 

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