The high purity and high strength graphite are commonly used in nuclear reactor and rocket structure material and the parts and devices required in fabrication of high purity metal, semiconductor materials and rare metal .
The high purity graphite used in semiconductor consumption , the high purity graphite used in single crystal furnace, the crucible boat and dish of semiconductor materials smelting and the devices in smelting high pure metal . The impurity content of this kind of graphite material is requested by <0.01%; the bulk density is 1.55 ~1.75g/cm3. Its production process is generally the same compared with ordinary graphite process ,but we must choose the ash content is less than 0.05% of the raw materials for the graphite material which formed by molded or isostatic pressure , high graphitization temperature and and accessing the halogen gas during the graphitization process ,we coat the pyrolysis graphite which the thickness in 10~20Hm on the surface of some high purity graphite devices in order to improve the oxidation resistance.
The high strength graphite used in the rocket engine , it is mainly used as the throat lining materials. It is necessary to meet the following severe working conditions: 2ooo degrees centigrade ~ 35 degrees Celsius temperature, the thermal shock caused by high-speed heating , the thermal stress caused by the maximum thermal gradients , sharply increased pressure; exposed in the high-speed corrosive gas for several minutes. The advantages of this kind of high strength graphite is relatively light, high temperature resistance and thermal stability.
The nuclear graphite, the nuclear graphite is used in nuclear reactor as the slowing down material and reflection material . It must have the performance of four aspects: high purity (0.5 xlO-6 boron content gas ni0.1) and high bulk density (1.65 -1.80g/cm3), high mechanical strength (compressive strength can reach 88.2 ~ 98.IMPa), low porosity and low gas permeation rate.
