Fired clay

A suitable cast iron crucible and cover, 1 quart capacity, is supplied by the Denver Fire Clay Compsiny, Denver, U.S.A. It can also be made from sheet iron. 

Glaze coatings (58) are appHed to dry or bisque-fired clay ceramics to form a strong, impermeable surface that is aesthetically pleasing. Protective ceramic coatings can also be deposited by CVD (68,90). Plasma activated CVD has been used extensively to produce diamond and diamondlike films. Diamond films can also be used to make optical coatings with a tailored refractive index. 

Clays are classified into six groups by the U.S. Bureau of Mines (1) kaolin, ball clay, fire clay, bentonite, fuller s earth, and common clay and shale. About half the toimage of clays produced in the United States is in the last category. In terms of monetary value, however, ka olin accounts for about two-thirds of the doUar volume. 

See also Bricks, fire clay) 115 800 0.62 Borosihcate type 139 30-75 0.63... 

Tne insulating firebrick is a class of brick that consists of a highly porous fire clay or kaolin. Such bricks are light in weight (about one-half to one-sixth of the weight of fireclay), low in thermal conductivity, and yet sufficiently resistant to temperature to be used successbilly on... 

Higb-duty fire clay SiOa, 54% AI263, 40% 134 3125 Acid Fair 18 Moderate Fair Fair Good Good at low temperatures... 

Feuer-steinknoUe, /. flint nodule, -stoff, m. (Old Phyaica) caloric, -strahl, m. jet or flash of fire, -ton, m. fire clay. 

Other applications of ceramics require clay, either raw or purified, sand, and feldspar. Brick, porcelain, and white wares are made from these raw materials the main expenditure in making these products is in firing the mixtures of powders to a dense solid. Ordinary brick made from fire-clay requires a small amount of energy even refractory brick for high temperatures and chemical durability, made partly from purified oxides such as alumina or chrome ore,... 

Archaeological Artifacts. A Lekythos Greek vase (500 years b.c.) was analyzed by backscattering Mbssbauer spectroscopy [365, 366]. This Lekythos vase has three black human figures with small red-painted details painted on a yellow-fired clay... 

Swollen clay materials are soft and easy to mould. They serve to produce ceramic materials. High quality fire-clay has a high kaolinite content. Upon firing, the intercalated water is removed first at approximately 100 °C. Then, beginning at 450 °C, the OH groups are converted to oxidic O atoms by liberation of water, and after some more intermediate steps, mullite is formed at approximately 950 °C. Mullite is an aluminum aluminosilicate, Al(4 )/3[Al2 Si,05] with x 0.6 to 0.8. 

Clays used in foundries include hydrous alumina silicates, known as bentonites. Their properties provide cohesion and plasticity in the green state and also high strength when dried. There are three clays that are commonly used in foundries western bentonite [sodium bentonite, burnout point 1290°C (2350°F)], southern bentonite [calcium bentonite, burnout point 1065°C (1950°F)], and fire clay [kaolinite, burnout point 1425°C (2600°F)]. 

Minerals (cassiterite (tin oxide), Pottery (fired clay and mineral or... 

During the dehydration stage (between 450°C and 600°C), hydroxyl (OH ) ions in the clay are dislodged from their molecules, combine with each other to form water vapor, and are thus removed from the clay structure and released into the atmosphere. It is during this stage, as a consequence of the displacement of the hydroxyl ions, that the chemical composition and the structure of the clay are irreversibly altered and converted to fired clay. 

Thermoluminescence measurements on a few milligrams of material scraped from fired-clay objects, such as pottery and figurines, can readily establish whether objects made of these materials are genuine antiquities, recent copies, or fakes. Chemical tests on what appeared to be a broken and restored terracotta statuette, purporting to be of Etruscan origin (from... 

Percy, J. (1861), Metallurgy The Art of Extracting Metals from their Ores and Adapting Them to Various Purposes of Manufacture, Murray, London reprint in two parts (ca. 1985) Vol. 1, Fuel Fire-Clays Copper Zinc Brass, etc. Vol. 2, Iron Steel, De Archaeologische Pers Nederland, Eindhoven. 

Percy, J. (1861). Metallurgy. Volume I Fuel Fire-Clays Copper, Zinc Brass. Murray, London. 

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