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Characteristics of heater materials |
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Vacuum Furnace _ Carbon material |
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It is reasonably priced and has
the operation temperature of the maximum temperature limit,
which makes it most widely used for the hot zone material of
a furnace. However, the carbon composition of the material makes
it susceptible for the carbon to affect the quality of the specimen.
By taking advantage of its mutual complementary property with
the atmosphere as well as the vacuum, various combination of
heat processes can be made.. |
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Heater characteristics |
- Thermal expansion and heat-distortion property
is comparatively low, which makes it to have strong
heat-resistance
- it gains more stiff strength as temperature goes up, with
the minimum characteristics shown at 500 ¡É
and then
the physical property becomes steady.
- Type : Plate, Rod, Pipe, circular, and spiral types. |
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Characteristics of insulating materials |
- Superior insulating property with standard
data low on physical properties.
- The surface coating prevents fine particles from being air-borne
while increasing the emission rate.
- Type : Rigid Felt(Sheet), Soft Felt, mold types |
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Type/structure application |
- Vacuum container and heating oven : rectangle
/ circular , vertical/ horizontal
- Heat element alignments : 2 sides, 4 sides , 6 sides (all-around)
- Loading of specimen: Front/Bottom/Top Loading |
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Relationship with atmosphere |
Atmosphere
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Rated |
Hydrogen |
Nitrogen |
Inert |
High vacuum |
Low vacuum |
Safe
temperature |
2500¡É |
1200¡É |
2200¡É |
2500¡É |
2000¡É |
2200¡É |
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Optional |
- Pyrometer ¢¢ T/C switching device
- Hot Press
- Extreme hot temperature package (up to 3000 ¡É )
- Pressurizing atmosphere and program cooling
- Retort (Tight Box)
- Binder/Wax Condensing Trap |
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Vacuum Furnace _ Refractory Metal material |
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As metals of high melting
points such as Moly & Sus, tungsten and tantal are
used as the Hot Zone materials, the advantage of using
them include the highly efficient heat transfer rate
and the capability to maintain the inside of the furnace
clean without corrupting the specimen, but the mechanical
fabrication and welding capabilities are their strong
points as care should be given to the design and manufacturing
process because of their high thermal expansion rate.
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Heater chracteristics |
- greater thermal expansion rate and tendency
to become brittle once exposed to heat, due to the
re-crystallization property
- Electric resistance between the ambient and hot temperatures
shows greater difference.
- Type : Rod(Wire), Sheet, Wire Mesh( Tungsten ) |
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Heat insulator characteristics |
- Layer assembly of the evenly-spaced thin sheets
of 1 mm or less.
- Surface with more gloss on the sheets shows better insulation
characteristics
- Type : SUS Casing & Sheets + Moly Sheets + (Tungsten Sheets)
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Type /structure application |
- Vacuum container and heating
oven : rectangle / circular , vertical/ horizontal
- Heat element alignments : 2 sides, 4 sides , 6 sides (all-around)
- Loading of specimen: Front/Bottom/Top Loading |
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Relationship with Atmosphere |
Atmosphere |
rated
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Wet hydrogen |
Dry hydrogen |
Nitrogen |
Inert |
Vacuum |
Safe
temperature |
Mo |
1750¡É |
1550¡É |
1750¡É |
1750¡É |
1750¡É |
1750¡É |
W |
2200¡É |
1600¡É
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2200¡É
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2200¡É
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2200¡É
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2200¡É
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Optional |
- Charge Carrier (Moly, TZM, W)
- Retort (Moly, TZM, W)
- Extreme hot temperature package (up to 3000 ¡É )
- program cooling device
- Pyrometer ¢¢ T/C switching device
- Binder/Wax Condensing Trap |
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Vacuum Furnace _ Other Hot Zone materials |
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| In addition to the graphite carbon
and refractory metals which are specifically used for super-high
furnace (Atmosphere), affordable and medium-priced materials
that are suitable for the required process can be used in designing
the hot zone and reconfigure the overall system. On top of the
vacuum furnace benefits, other heat process can be devised with
the use of other types of gases. |
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Hot Zone materials |
- Heat material : Kanthal(FeCrAl), SiC, MoSi2
- Heat insulator : High Alumina Board/Felt, Sandwich Panel,
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Heater characteristics |
- common property : The usage quality of the
materials becomes low as the oxide film is dissolved for both
vacuum and reducing atmosphere.
- Kanthal : Weak high-temperature strength and tendency to become
brittle after being exposed to heat, as well as
having the characteristics of positive temperature coefficient
of resistance.
- SiC : The coefficient of resistance characteristics becomes
negative from the positive temperature at 700 ¡É , and
the increase of voltage is necessary as the resistance increases
as time progresses.
- MoSi2 : Installed vertically due to the hot restoration characteristics
while maintaining positive temperature coefficient
of resistance. |
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Type/ structure application |
- Vacuum container and heating
oven : rectangle / circular , vertical/ horizontal
- Heat element alignments : 2 sides, 4 sides , 6 sides (all-around)
- Loading of specimen: Front/Bottom/Top Loading |
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Relationship with atmosphere (Maximum operating temperature
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Atmosphere |
Rated |
Wet Hydrogen |
Dry Hydrogen |
Nitrogen |
Inert |
Vacuum |
Safe
temperature |
Kanthal |
1200¡É |
1200¡É |
1200¡É |
1000¡É |
1200¡É |
1150¡É |
SiC
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1500¡É
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1250¡É
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1300¡É
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1300¡É
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1500¡É |
1200¡É
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MoSi2
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1800¡É
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1500¡É
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1400¡É
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1700¡É
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1700¡É |
1200¡É
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