Vacuum, Protective Gas or Hydrogen Furnaces

Cold wall furnace with protective gas atmosphere or vacuum

HTM’s cold wall furnaces are suitable for work in oxygen-free atmospheres at temperatures up to 2400 °C.
Depending on the materials used for the heating conductor and the thermal insulation, different application specific versions are available. By using oxygen getters in the thermal insulation, extremely low-oxygen gas atmospheres or – in a modified version – high vacuum can be achieved. The usual working space volumes range from 0.5 l to 20 l.
The table below provides an overview of the heating systems and their characteristics.

Material of the heating conductor Material of the thermal insulation Maximum 
temperature
Gas atmosphere
Mo (molybdenum) Alumina 1850 °C Hydrogen, inert gas (low humidity, carbon-free)
W (tungsten) High temperature oxides 2100 °C Hydrogen, inert gas (carbon-free)
W (tungsten) W/Mo radiation shields 2400 °C Inert gas, carbon monoxide
Graphite Graphite fiber 2500 °C Inert gas, hydrogen (carbon-free and oxygen-free)

Cold wall furnaces with protective gas atmosphere are used for different processes, such as:

  • Sintering of oxygen-sensitive ceramics, such as AlN (aluminum nitride), Si3N4 (silicon nitride), BN (boron nitride), CeS (cerium sulfide);
  • Sintering of oxides, while adjusting low oxidation stages; for example MnO, TiOx, Ce2O3, UO2;
  • Generation of defined structures and properties in redox-stable oxides;
  • Thermal treatment and sintering of oxygen-sensitive metals, such as tungsten, molybdenum, tungsten-nickel-titanium alloys;
  • Production of metal/ceramic joints according to the active metal solder technology
  • Annealing of impurities (like alkali / alkali oxides) from high temperature materials

Vacuum, Protective Gas or Hydrogen Furnaces

cold wall furnace

cold wall furnace

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