CHAMBER AND HOT ZONE
The Top Loading Hot Zone chamber is cylindrical in shape and is manufactured from double-walled stainless steel. The entire chamber is welded and polished for vacuum integrity and an ergonomic appearance.
Numerous chamber ports are supplied for sensors, vacuum, gas, hot zone power and a sight window. The standard hot zone is made from Tungsten and Molybdenum (different materials available), with 7 shield layers to reduce power loss. The specimen rests on a tungsten hearth. Power connections to the heating elements are secluded on the bottom of the chamber and are water-cooled.
PROCESS GAS SYSTEM
This furnace system was designed to operate in several positive pressure gas environments as well as partial pressures (below atmosphere) of gas such as dry or wet Hydrogen, Dissociated Ammonia, Nitrogen or Argon. The maximum operating pressure is 5 PSIG. A pressure relief valve and 30/30 compound gauge are located on the top chamber of the furnace body.
For flammable gases, a gas burn-off and explosion port is provided in accordance with NFPA requirements.
Mass flow controllers are available for programmable gas flows in lieu of manual flow controls.
The turbo high vacuum pumping system on this furnace is capable of evacuating the furnace into the 10-7 Torr vacuum range. The pumping system quickly removes oxygen from the inside of the furnace to allow a back-fill with gas or to run the furnace in a high vacuum atmosphere.
The pumping system consists of the following:
- A rotary vane pump with an exhaust filter for rough vacuum and turbo pump back-up.
- A turbo pump (other pumps available) for high vacuum.
- Electro-pneumatic vacuum valves are provided to operate the vacuum system or to isolate the chamber in case of operation in process gas.
- A vacuum relief valve (back to atmosphere) is provided for the purpose of releasing the pressure or to conveniently leak check the system.
- PC interface screens are provided to monitor and operate the status of the pumping system.
- Vacuum gauges and an ionization gauge are supplied to monitor vacuum levels.
Power to the heating elements is supplied by an SCR-controlled transformer package allowing high ramp-up speeds up to the maximum temperature of 2500°C. The transformer has several secondary voltage tabs to allow for hot zone aging without performance degradation.
All of the furnace controls are mounted in the control enclosure while circuit breakers, contactors, instruments and wires are mounted in the power supply enclosure. Hot zone power and temperature are controlled by the HMI control system.
The furnace temperature is controlled through the SCADA/HMI control system. The operator interface consists of an industrial touch panel PC with an intuitive user interface (other control systems available). The HMI features graphical overviews and controls for the vacuum system, gas system, temperature control system, and includes alarms, trends, temperature recipe management, configuration settings and user security. Data is logged and stored on disk, which can be used for display, analyzing or reporting..
At low temperatures a type “C” thermocouple is used to control the furnace temperature. Once the pyrometer is within its operating range, it will take over control of the furnace temperature . The control system automatically switches seamlessly between the two sensors at a programmable temperature.
The water system is designed to adequately cool the furnace components so no exterior surfaces exceed 120°F (45°C). A water flow switch is installed for visual indication and to interlock power to the heating elements. In the event water flow is interrupted for more than 5 seconds when the furnace hot zone is operating, the power will be disconnected to the heating elements.
The water manifold has several circuits supplying water to the various parts of the furnace. Each one of these can be manually adjusted to allow each circuit just the proper amount of flow to minimize heat and energy losses.
||40 kVA, 380-480V/3/50-60 Hz (other voltages available)
||8 G.P.M. (30 lpm) @ 20°C (70°F) and 50 P.S.I.G. (3.4 bar)
||Ar, N2 & He, 30-60 lpm @ 30 P.S.I.G. (2 bar)
||H2 or NH3, 30-60 lpm @ 30 P.S.I.G. (2 bar)
||60-90 P.S.I.G. (4.1 – 6.2 bar) filtered