Carbon and graphite felts are used in resistance or induction heated vacuum furnaces and inert gas furnaces as high temperature insulation.
Felts are made of carbon or graphite fibres, these materials have low thermal conductivity and vapour pressure. They can be used in oxidizing atmospheres up to 350 °C and in protective atmosphere or vacuum up to 2800 °C.
Carbon and graphite felts are less expensive and more effective than metallic radiation shields and may be used to replace them, with power savings of up to 75 %. The low specific heat and low density permit rapid heating and cooling of furnaces.
Carbon and graphite felts can be cut easily using scissors or knife and have small bending radii.
We can supply a wide range of felts in different qualities (PAN carbon, PAN graphite, Viscose carbon, Viscose graphite), thicknesses and widths.
Available Types and Sizes
NGF-BV Rayon Graphite Felt
Properties
|
NGF-BV Rayon Graphite Felt
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NGF-BV3
|
NGF-BV6
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NGF-BV12.5
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Nominal thickness (mm)
|
3.125
|
6.25
|
12.5
|
Thickness (mm)
|
3.0 – 3.3
|
6.0 – 6.5
|
12.2 – 12.9
|
Density (g/cm3)
|
0.08 - 0.11
|
0.08 - 0.11
|
0.08 - 0.11
|
Tensile strength (MPa)
|
longit.
|
0.23 – 0.28
|
transv.
|
0.18 – 0.23
|
Resistivity (Ωmm)
|
longit.
|
2 – 3
|
transv.
|
4 – 5
|
Thermal conductivity (1000°C) (W/m·K)
|
0.08 – 0.10
|
Carbon content (%)
|
>99.5
|
Ash content (%)
|
<0.5
|
Process temperature (°C)
|
2300
|
Standard sizes
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Length (m)
|
20 Max.
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Width (m)
|
1.067(42"), 1.22(48")
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Thickness (mm)
|
3.125(1/8"), 6.25(1/4"), 12.5(1/2")
|
Characteristics and Benefits
- Low thermal conductivity: Superior to that of loose particle fillings like granular carbon or metal radiation shields (saving energy up to 75 %)
- Low specific heat: Permits rapid heating and cooling of furnace
- High thermal stability: In oxidizing atmosphere up to 350 °C, in protective atmosphere or vacuum up to 2800 °C
- Favourable resistivity: Coupling in an inductive field occurs only above 12 kHz
- Easy to use: Can be cut with scissors or knife. Flexible
- Favourable surface properties: Unaffected by nearly all molten metals. Small specific surface area – low adsorption capacity; surface may be increased by partial oxidation
- High purity: Low sulphur content – no contamination of pump oil in vacuum operation. Low ash content – no smouldering
- No electrostatic charging: No electrostatic charging when used together with plastics in composite materials
Applications
- Aerospace: Hot isostatic process furnaces, heat treating, sintering, brazing furnaces, autoclaves
- Semiconductors: Silicon pullers, gallium arsenate producers, monocrystal furnaces
- Metallizing (metal heat treating): Heat treating furnaces, sintering, brazing furnaces
- Fiber composites manufacturing: Carbonizing furnaces, graphitizing furnaces -induction or resistance tube furnaces
- Ceramics: Pyrolytic depositing furnaces, sintering furnace CVD furnaces, CVR furnaces
- Quartz/fused silica manufacturing: Melting/sintering furnaces
- Glass industry: Insulating fasteners (part of liners)
- Tool manufacturing: Sintering and hot pressing
- Others: As conducting electrode in fuel cells