Muffle furnace

A muffle furnace is a furnace in which the heat source of the Brenngutkammer by a heat-resistant insert - a muffle - is disconnected. The muffle is usually made of fireclay and can have fixtures made ​​of steel.

Areas of application

Muffles are used in the laboratory use to protect the feedstock from flames or direct Heizelementstrahlung or to the electric heating elements to protect against gases emanating from the feedstock. Are muffle furnaces for incinerating and annealing and thermal treatment of workpieces ( eg hardening of steel, ceramic sample fires or carbon deposits etc.). Muffle Furnaces are used for different gravimetric methods of chemical analysis, to bring small amounts of a substance in the Wägeform and prevent foreign entry.

In soil science and geomorphology muffle furnaces are used to determine the organic matter and the carbon content in soils by calcining. These temperatures are required to 430 ° C.

The combustion chamber of a crematorium (for details see also cremation ) is also called a muffle furnace. It is lined with fireclay, which were heated before the cremation at a temperature of about 900 ° C. The first phase of cremation (burning of the coffin ) performed exclusively with the heat thus stored; during this phase of incineration, no additional energy is supplied by gas burners. An optimal and environmentally friendly cremation is achieved by a balance between temperature and supplied by a blower air oxygen. Using sensors in a muffle furnace, these parameters are optimally controlled by a computer. Can during incineration - also by the combustion of the coffin - temperatures up to 1000 ° C may occur.

As a muffle furnace or muffle since the 18th century, is a specially designed for the color of fire ceramic glaze colors furnace called, in which the combustion gases ( " smoke ") and the resuspended ash can from the combustion chamber does not come into contact with the ceramic, but the outside to pull off along the sealed walls of a separate Brandgutkammer and finally by a trigger. This chamber through the walls heated up to 800 ° C so that the glaze colors - also called muffle colors - to sink into the glaze of ceramic. A separate vent in the top of this chamber can escape from the vapors of the color materials and solvent.

Also as a special muffle furnace design was called, which was formerly used for the extraction of zinc.