Pyrolytic graphite is a new type of carbon material, it is the high crystallinity pyrolytic carbon under the high pure hydrocarbon gas in the furnace pressure and one the graphite matrix which is in 1800 DEG C to 2000 C through the chemical vapor deposited, it has a high density (2.20g/cm), high purity (impurity content is 0.0002%) and the heat, electricity ,magnetism and mechanical properties anisotropy . The vacuum degree of 10mmHg can still be maintained at about 1800 DEG C.
Pyrolysis is the process of decomposition of a substance by heat. The decomposition reactions will occur when many inorganic substances and organic matter are heated to a certain degree .The pyrolysis process does not involve the reaction of the catalyst and other energy, such as UV radiation. Pyrolytic graphite is obtained through this process.
The main characteristics of pyrolysis graphite:
The surface of pyrolytic graphite is dense and without the pore , so it is easy to machine.
Pyrolytic graphite has high purity, total impurity content is less than 20ppm, it’s in good air tightness.
High temperature resistance, the strength of the pyrolytic graphit increased with the temperature increasing, the strength reached the highest value at 2750℃and it will sublimate in 3600℃.
The pyrolytic graphite products have the low elastic modulus, high thermal conductivity, low thermal expansion coefficient and the good thermal shock resistance.
Pyrolytic graphite has good chemical stability, it can bear the acid, alkali, salt and organic reagent and has no effect with molten metal, slag and other corrosive media , its oxidation is not obvious in the atmosphere and the temperature below 400℃, the oxidation rate increased significantly at 800℃.
The pyrolytic graphite does not release any gas under high temperature and can maintain the vacuum of 10-7mmhg at about 1800℃.
Pyrolytic graphite is mainly used in graphite heater, diversion barrel, PBN/PG composite heater and atomic absorption tube.