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crucible,vessel in which a substance is heated to a high temperature, as for fusing or calcining. The necessary properties of a crucible are that it maintain its mechanical strength and rigidity at high temperatures and that it not react in an undesirable way with its contents. Porcelainporcelain
[Ital. porcellana], white, hard, permanent, nonporous pottery having translucence which is resonant when struck. Porcelain was first made by the Chinese to withstand the great heat generated in certain parts of their kilns.
..... Click the link for more information. , iron, and platinum are used in the lab; graphitegraphite
, an allotropic form of carbon, known also as plumbago and black lead. It is dark gray or black, crystalline (often in the form of slippery scales), greasy, and soft, with a metallic luster.
..... Click the link for more information. is usually used in industry, but firebrickfirebrick,
brick that can withstand high temperatures, used to line flues, stacks, furnaces, and fireplaces. In general, such bricks have high melting points that range from about 2,800°F; (1.540°C;) for fireclay to 4,000°F; (2,200°C;) for silicon carbide.
..... Click the link for more information. is also used, especially when vessels of large capacity are needed. The chamber at the bottom of a metal-refining furnace, where the molten metal collects to be drawn off, is known as a crucible.
a vessel for melting, founding, or heating various materials. Crucibles are used, for example, for melting metals and alloys, for heat-treating metal objects in a controlled atmosphere or in liquid media (seeTANK FURNACE), for glassmaking, and for melting and calcining substances in the laboratory (seeLABORATORY VESSELS, CHEMICAL). Depending on the temperature of treatment and the chemical properties of the materials being treated, a crucible may be made of metal (pig iron, heat-resistant steels and alloys, or platinum), graphite, porcelain, or refractories. Crucibles are usually round in cross section and narrower at the bottom. In many industrial furnaces, materials are treated in crucibles inside the furnace itself.