● Introduction
PG is a new carbon material. PG is made from the high-purity hydrocarbon gas in furnaces at a certain pressure and the temperature always between 1800 and 2000 degree. The pyrolytic carbon layer with high crystal orientation is synthesized on a graphite body by chemical vapor deposition. PG is characterized by high-density(2.20g/cm3), high-purity(impurity content 0.0002%) and anisotropy in thermal, electricity, magnetic and mechanic performance.
● Characteristics
1. Surface densification and pore-free, easy to machine.
2. High-purity, total impurity content ＜20ppm and good gas barrier property.
3. Heat-resistance, the strength increases with temperature and peaked at 2750℃, sublimated at 3600℃.
4. Low elastic modulus, low thermal expansion coefficient, high thermal conductivity and excellent thermal shock resistance.
5. Excellent chemical stability, acid, alkali, salt and organic reagent
resistant, not reacting with the majority of molten metal, slag and
other corrosion, no obvious oxidation in the atmosphere below 400 ℃ and
the oxidation rate increase significantly from 800℃.
6. None releasing gas at high temperature, maintaining a10-7mmhg vacuum at about 1800 ℃.
● Parameter
| property | unit | value | |
| density | g/cm3 | 2.2 | |
| Helium transmittance | cm3/s | <1×10-12 | |
| tensile strength | Mpa | room temperature | 2750℃ |
| 98(strength⊥"c") | 264(strength⊥"c") | ||
| compressive strength | Mpa | at room temperature | room temperature |
| 64.11(strength⊥"c") | 304(strength∥"c") | ||
| bending strength | Mpa | room temperature | room temperature |
| 127(strength⊥"c") | 118(strength∥"c") | ||
| thermal conductivity | W/m.K | 376("a") | 2("c") |
| thermal expansion | 10-6℃-1 | 1.26 ("a") | (50－800℃) |
| resistivity | Ω·m | 2×10－4("a") | 0.5("C") |
● Application
It is utilized in the draft tube for pulling silicon single crystal in the semiconductor industry.
PG material can be used as the coating of graphitic heaters in the semiconductor industry.
PG material also can be used as the coating of PBN-PG composite heater used in annealing technology of crystal plate.
The crucible of PG material can be used for electron beam evaporation of aluminium.
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