Chamber and Hot Zone
The furnace chamber provides an isolated atmosphere for the sample and is made of double-walled electro-polished stainless steel to allow water cooling and excellent vacuum performance. An external temperature below 50 °C is maintained at all times. Access to the sample is by means of a hinged front cover.
The hot zone is sized* to accommodate customer samples and provides excellent temperature uniformity. The hot zone heating element and shields are typically made from Molybdenum, Tungsten, Graphite or Ceramics. The power supply for the heater is sized for the maximum temperature and has extra power for less efficient aging hot zones.
With a maximum operating temperature of 2300°C**, this furnace is capable of processing any high temperature material under physical test conditions.
* Many hot zone sizes available, consult MRF for details.
** Physical test accessories can limit maximum temperatures
Test Frame
MRF works with the customer and test frame supplier to ensure full compatibility of the furnace chamber with the test frame. We provide ample ports and access lids to accommodate accessories such as grips, extensometers, test rods, samples, etc and to provide access to the required hot zone areas. The chamber is sized according to the sample dimensions and the test sample mounting accessories.
Power Supply & Controls
Power to the hot zone is supplied by an SCR-controlled power supply, including a circuit breaker, a contactor, an SCR to modulate the power to the hot zone, a main step-down transformer matched to meet the heating element resistance, volt and amp meters, and a set of water-cooled power cables to supply power to the furnace.
Temperature control is accomplished either with classic instruments or with a Programmable Logic Controller (PLC) & PC. The HMI interface, with an easy-to-use computer touch panel, replaces the individual controllers and switch panels. The HMI allows the user to control, view and record all furnace functions, allowing for data acquisition, recipe storage, trending, alarms and networking.
A type “C” sheathed and coated thermocouple is supplied and can be used to measure the furnace temperature up to 2000 °C. When operating the furnace to temperatures above 2000 °C, control is automatically switched over to a Pyrometer.
Vacuum and Gas System
The evacuation system consists of a Rotary Vane Mechanical Pump, an electro-pneumatic vacuum valve, vacuum gauge controller and a vacuum gauge. This vacuum system will allow for operation in a vacuum environment (10-2 Torr range). A 4″ or 6″ diffusion pumping system or a turbo pumping system can be provided as well and can achieve vacuum levels down to 10-6 with a diffusion pumping system and 10-7 Torr range with a turbo pumping system. A manual valve is provided for leak checking or air-releasing the roughing line.
The gas system is supplied to provide an inert environment for the work samples during the heat and physical testing. The process gas system includes a solenoid-operated inlet valve, a compound gauge (30 P.S.I.G. x 30 in. Hg.), a gas flow meter, and a 2 P.S.I.G. outlet relief valve to maintain a positive pressure. There is also a 5 P.S.I.G. over-pressure safety relief valve. Flammable or reducing gases are options.
Water Cooling System
The Furnace Water Cooling Manifold consists of multiple circuits to adequately cool all the furnace parts and includes a strainer, pressure regulator, pressure gauge, water inlet and outlet manifold, a water flow switch as a visual water flow indicator with a flow interlock to protect the furnace in the event of a water flow failure. This switch turns off power to the hot zone contactor if water flow is below recommended minimum for a certain amount of time. Each part of the furnace is supplied with a separate cooling circuit that can be regulated by independent manual ball valves.
Utilities
| Power: |
kVA dependent on max temperature rating, 380-480 V/3/50-60 Hz (other voltages available). |
| Water: |
70F (20 °C) and 50 P.S.I.G. (3.4 bar), required flow dependent on kVA rating. |
| Process Gas: |
Argon or Nitrogen 30 L.P.M. @ 50 P.S.I.G. |
| Compressed Air: |
60 – 90 P.S.I.G. (4.1 – 6.2 bar) filtered. |
