High vacuum laboratory furnace model CRYSTALOX, with metal thermal chamber, metal resistor and forced cooling with noble/neutral gas circulation.
The vacuum furnace is connected to two gas supplies:
- The neutral gas is used for washing, cooling, and to quickly fill the furnace when needed.
- The process gas (H2 CO) is introduced to change the composition (surface) of the material to be processed (reduction processes).
Merkmale
Size (WxHxL): 1.5x2.2x3.5 m
Hot zone (WxHxL): 250x250x450 mm
Max temperature: 2000 °C
Charge: 15 kg
Final vacuum: 1E-6 mbar
Operating vacuum: 1E-5 mbar
Details
The vacuum chamber is fixed to prevent vibration to the tungsten mesh.
The top case back is moved with a pneumatically operated fork.
The fork is guided by 2 slides on ball bearings.
A safety device blocks the lowering of the port case back.
The vessel:
- Made of a double water-cooled wall, cylindrical, vertical axis, with rounded bottoms above and below.
- At the top there are the exchanger group, the impeller and the engine.
- Impeller and motor can be easily removed.
- The loading base, inside the chamber, is easily accessible for loading and unloading parts.
- Flanged for connection to the pumping group.
The thermal chamber:
- All-metal is made from a tungsten mesh and powered by a low-voltage three-phase system.
- Heat shields border the hot zone by creating a system of multiple reflections and limiting the dissipated power.
- The screen pack is made of more refractory materials on the inside and less refractory materials on the outside.
- Two thermocouples drive the furnace and achieve over-temperature safety.
The pumping unit:
- Two-stage roughing pumps.
- Diffusion pump.
- Pneumatically operated high vacuum, bell prevacuum and diffusion prevacuum valve.
- Fine gas regulating circuit and fine gas inlet regulating valve.
- Gas inlet circuit and guards (pressure switch, vacuum switch, vacuum measuring head, gas inlet regulating valve).
- Pressure maintaining device with changing gas temperature.
The cooling system is forced convection: at the end of the heating phase, the gases are automatically replaced, the exhaust valve is closed and the pressure is regulated between 1050 and 1150 mbar absolute.
When the temperature of the furnace has reached a predetermined value (which must be below 1000°C anyway), the impeller is automatically started.
The hot gas, drawn from the impeller through the charge, is circulated on a heat exchanger to which the energy drawn by forced convection yields.
This provides a fast cooling of the charge and the thermal chamber.