Crucible

A crucible, a refractory and chemically resistant vessel for heating of materials or for the preparation of melts. It may consist, for example, a ceramic ( refractory clay, alumina, zirconia, and graphite ), glass or metal.

Laboratory crucibles are used in a typical tapered bottom mold to be heated in a Tondreieck in a flame. In addition to the simple crucibles made ​​of porcelain, which are mostly used only once, nickel, platinum and quartz glass crucible are the most common materials. Platinum crucible may include, but are attacked, can be used at very high temperatures, however, there is some test materials, the risk of rupture also the chemical or vulnerability. Quartz glass crucibles are extremely resistant to temperature changes and can be red hot quenched in cold water without suffering damage. Often one uses a lid to prevent evaporation and avoid the cooling of the interior.

As a crucible shoe is called a niedrigwandiges container made ​​of porcelain, in which the pot can be adjusted. Crucible shoes prevent contamination of the ovens when the pot overflows or breaks.

A special case is the Rose crucible which is used in the gas stream for heating solid matter sample. It is covered with a pierced lid, through which opening serves to supply an angled porcelain tube of the gas concerned.

In Saxony and Thuringia pot often referred to a frying pan. Conversely referred pan a large industrial crucible steel production ( steel ladle ).

Labeling of porcelain crucibles

For permanent marking porcelain crucibles of the numbers with an aqueous solution of a cobalt salt ( (II ) nitrate eg cobalt) thinly on the bottom of the crucible. Then they are dried and calcined, the label then remains permanently legible in black color.