Furnaces Globar

Globars" (silicon carbide rods) are the next most frequently used furnace heating elements. They will operate continuously at 1450 °C. and intermittently at 1500 C. A newer t3q>e of element. Mo wire coated with silicide, i.e.- MoSi2(to protect the Mo wire against oxidation), heis become... 

Fig. 11. Globar furnace 1—External jacket (metal) 2—insulation layer (fireclay grit, MgO,diatomaceousearth) 3— insulation support tube (fireclay) 4— Globars 5—inner tube (Sillimanite, hard porcelain) 6—end plates drilled for the inner tube and the Globars.

As shown in Fig. 225, an unglazed porcelain boat is charged with 20 g. of very pure silicon and placed in a porcelain or quartz tube (30-40 mm. diameter, 800 mm. lot ), placed in a Globar tubular furnace. The boat is pushed to the hottest part of the furnace. The temperature should be about 1150°C at this point. The ends of the tube, which extend beyond the furnace, are wound with lead cooling coils and are closed with well-seated rubber stoppers c and d. The stoppers are painted with quick-setting chlorinated rubber cement to ensure a better seal. The flask o, which contains SiBr 4, is first cooled to at least -80°C and Is then very slowly... 

Modem sources for the mid-IR region are variants of the incandeseent wire source or the Globar, but generally in a compact geometry. Commercial furnace ignitors and diesel engine heaters such... 

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