carbon refractory[′kär·bən ri′frak·trē]
any of a group of refractories consisting almost entirely of carbon or containing from 5 to 70 percent carbon in addition to other refractory components. All-carbon refractories are made from coke, thermoanthracite, and coal tar by a roasting process in a reducing medium at temperatures of 1100°-1450°C (nongraphitized refractories) or approximately 2500°C (graphitized refractories). Graphite refractories are produced from natural or artificial graphite. Carbon-containing (graphite-containing) refractories are shaped by various methods from mixtures of graphite, clay, grog, and other refractory powders and then either roasted at 800°-1350°C or finished without roasting.
Carbon refractories have an apparent density of 1,500–2,000 kg/m3, a porosity generally in the range from 15 to 30 percent, and high thermostability. In oxidizing media, the refractories undergo oxidation relatively rapidly. The materials are produced either as blocks of various sizes or as shaped pieces, for example, stoppers, beakers, pipes, and crucibles. All-carbon refractories are used in lining the hearths and wells of blast furnaces and the bottom of furnaces used in nonferrous metallurgy and in the production of calcium carbide. Graphitized and graphite refractories are used in furnaces producing special alloys and in rocket engines, while graphite-aluminosilicate refractories are used in the pouring of steel and the smelting of nonferrous metals. Use is also made of mixtures in the form of pastes of carbon or graphite powders in a resin binder.
REFERENCEKhimkheskaia tekhnologiia keramlki i ogneuporov. Moscow, 1972.
A. K. KARKLIT