Crucibles

Crucibles are vessels designed to withstand high temperatures and to contain substances during heating, melting, calcination, or other high-temperature reactions. They are used in metallurgy, chemistry, geology, and materials science. Common crucible materials include porcelain or other ceramic compounds, quartz or high-silica ceramics, alumina or magnesia refractory ceramics, and graphite. Some crucibles are lined or coated to resist reaction with contents or to reduce leaching, and they may be opened or fitted with lids, handles, or pouring spouts.

Historically, crucibles have been used since ancient times, with clay and ceramic vessels employed for smelting and alloying. Developments in refractory materials during the 19th and 20th centuries produced more durable crucibles for laboratory and industrial use, including graphite crucibles that offer high thermal conductivity and chemical resistance, and high-purity ceramic crucibles for analytical work.

Applications include melting and alloying metals in metallurgy, ashing organic matter and performing calcination in chemistry, and holding melts or fluxes in glass and ceramics processing. In analytical laboratories, porcelain or silica crucibles are used in gravimetric methods and other high-temperature sample preparations.

Handling and safety considerations involve heating crucibles gradually to minimize thermal shock, inspecting for cracks or damage before use, and using appropriate tongs and protective equipment. Damaged crucibles should be discarded, and care is taken when heating reactive materials to avoid unwanted reactions or contamination.