GENERAL DESCRIPTION
Coatingmaster furnaces are vacuum furnaces designed for chemical vapor deposition (CVD)
and chemical vapor infiltration (CVI) of refractory ceramic and metallic coatings.
Standard furnaces are rated for use to 1600°C, with an optional upgrade to 2200°C for
pyrolytic graphite and other high temperature deposition processes.
Each vacuum furnace is supplied as a complete system including: vacuum
chamber; hot zone; power supply; vacuum pump; and a programmable control system. Manual
process controls are provided for two reactant gases and one inert blanket gas. Additional
flow channels are optionally available, as well as fully automatic process and blanket gas
control systems.
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Top Loader
(Model 612) |
Front Loader
(Model 121212) |
Bottom Loader
(Model 1624) |
CHAMBER AND HOT ZONE
Coatingmaster vacuum furnace vessels are manufactured with stainless steel,
including the chamber, water jacket, and all flanges. Process gas and vacuum pump
manifolds are also made with stainless steel, as well as any additional piping which may
come in contact with chlorinated or fluorinated gases. Nickel gaskets are used as vacuum
seals on small diameter piping where practical, and Viton O-rings on larger diameter
flanges such as the main door and vacuum pumping system ports.
Graphite hot zones are used on all Coatingmaster vacuum furnaces, including graphite
resistance heating elements and low density fibrous graphite insulation. Internal graphite
retorts are also supplied to provide a barrier between blanket and process gases, thereby
containing reactive gases and effluents. A graphite exhaust tube directs effluent gases to
the pumping system while a gas supply manifold brings reactants into the retort. Internal
gas distribution manifolds are normally provided by the user, or custom designed to meet a
specific application.
Top Loading
Heat Zone |
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Front Loading
Heat Zone |
VERTICAL CVD/CVI VACUUM FURNACES*
GAS CONTROLS
Coatingmaster vacuum furnaces include a basic gas supply system that can be
upgraded to meet individual requirements. The basic system includes two corrosion
resistant rotometers with manual needle valve controls; a laser welded stainless steel
diaphragm pressure gauge, and manual blanket gas controls. The blanket gas controls
include a shut-off valve, rotometer flow indicator, and a needle valve to adjust the flow
of protective inert gases which surround the retort.
Optional enhancements include mass flow controllers, automatic retort
pressure control systems, and automatic blanket gas pressure control systems. See
schematic drawing below.
The automatic retort downstream pressure control system includes an
absolute pressure capacitance manometer, a proportional control valve on the retort
exhaust manifold, and a pressure control panel for maintaining process gas pressure at a
constant level.
The automatic blanket gas upstream pressure control system uses a
differential pressure capacitance manometer to monitor the pressure difference between the
inside and outside of the retort. A set-point control panel maintains a constant positive
pressure differential outside the retort by adjusting a proportional valve which controls
inert blanket gas flow.
Coatingmaster vacuum furnaces must be furnished with a combustible gas safety
system if explosive concentrations of combustible gases will be present. This optional
system includes a blow-off port, burn-off tower, and extensive safety interlocks. Blow off
and pressure relief ports must be properly vented by the user.
SPECIAL FEATURES
Corrosion resistant vacuum pump, gauges, and fittings
Complete stainless steel chamber construction
High temperature capability to 2200°C
Choice of manual or fully automatic gas controls
Optional top and bottom heaters for improved uniformity
Large power supply for rapid heating
Including graphite retort for vapor containment
Complete instrumentation package including temperature sensor, programmable
microprocessor, and gas controls
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VACUUM
PUMPS
Coatingmaster vacuum furnaces are supplied with corrosion resistant two stage
mechanical vacuum pumps designed for operation with chlorinated and fluorinated gases.
Standard pumps are sized for rapid chamber evacuation to less than 0.1 torr in
approximately five minutes.
The chamber can then be backfilled for deposition near atmospheric
pressure, or operated above one torr with moderate gas flows. Deposition at lower
pressures or with high gas flows will require a larger pump or the addition of a
mechanical booster pump.
All pumps are normally provided with high-grade hydrocarbon oil.
Synthetic inert fluids can be optionally provided, as well as oil filtration systems,
inlet traps, and mist eliminators.
POWER SUPPLY
Two different power supplies are available for each Coatingmaster,
depending on whether the furnace will be used to 1600°C or 2200°C. Each supply is
generously sized with ample reserves for load heatup and compensation for heat zone aging.
Furnace heatup time to full temperature is typically one to two hours or less.
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ADDITIONAL
INSTRUMENTATION
Microprocessor based programmable controllers are provided for all
furnaces. The standard controller is capable of storing ten ramp and ten soak segments as
well as two process events such as pump-down or backfill. Controllers with more extensive
capabilities are optionally available, as well as custom designed control systems to meet
any requirement.
Temperature sensing is done with a tungsten- rhenium thermocouple, or
optionally with an infrared pyrometer. Independent over-temperature control systems using
either a thermocouple or power transducer are also available. Two thermocouple gauges
measure vacuum and a PLC coordinates system functions and provides safety interlocks.
Typical Control
Cabinet
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- pyrometer or TC
- ionization gauge
- TC gauges
- programmable logic controller
- voltmeters
- ammeters
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INSTALLATION
Thermal Technology can provide assistance in selecting and installing
scrubbers, gas bubblers, gas cabinets, mass spectrometers, exhaust hoods, and related
equipment. Changes will be based on actual engineering time involved, field personnel time
and travel expenses, subcontractor payments, and equipment costs.
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CUSTOM FURNACE DESIGN Our engineering team can design a custom
vacuum furnace system to meet your exact
requirements. When your needs exceed the capabilities of our standard models, you can
count on receiving the same quality and reliability in a customized system. Typical
reasons for needing a customized system include larger work loads, specialized control
requirements, and proprietary gas handling systems.
Extensive design, fabrication, and testing skills
are available for use in developing furnaces built for a specific application. Our custom
designed vacuum furnaces are located at national laboratories and major corporations around the
world. When you need the best—call Thermal Technology. |
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