CHAMBER AND HOT ZONE
The standard hot zone material choice for sintering applications is tungsten (2500°C maximum) or tantalum (2100°C maximum). Molybdenum and graphite hot zones are also available. Layered heat shields surround the load and heating element to reduce power loss. The specimens or parts rest on a removable load assembly. The load assembly is manufactured from the hot zone material when material compatibility is a concern.
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 appearance.
Numerous chamber ports are supplied for sensors, vacuum, gas, hot zone power and a sight window.
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 gasses, 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 pumping system on this system 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 backfill 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 relief valve (back to atmosphere) is provided for the purpose of releasing system vacuum or pressure, or to leak check the system.
- PC interface screens are provided to operate and monitor 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 overviews and controls for the vacuum system, gas system, temperature control system, and includes alarms, trends, temperature recipe management, configuration settings and security. Data is logged and stored on disk, which can be used for display, analyzing or reporting.
At low temperatures a type “C” thermocouple will be used to control the furnace temperature. Once the pyrometer is within its operating range, it will take over control. The control system will automatically switch 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 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 L.P.M. @ 50 P.S.I.G. (3.4 bar)
||H2 or NH3, 30-60 L.P.M. @ 50 P.S.I.G. (3.4 bar)
||60-90 P.S.I.G. (4.1-6.2 bar) filtered.