High Purity Carbon Carbon Composite Crucible

Monocrystalline silicon single crystal growth furnace are Cz method and floating zone (Fz) method of figure 1 is a structure schematic of Cz silicon single crystal furnace, under the aegis of the argon gas will polysilicon heated to a temperature of about 1500, make its melting: by the upper furnace rotation lowered crystal seed (kind of) guy, make its contact with molten silicon surface, and make molten silicon surface heat preservation at around 1400, upward pulling seed and monocrystalline silicon also gradually generated, always grow to the size of the design, such as 15.24 20.32 25.4 and 30.48 cm
It can be seen from Figure 1 that in addition to fused silicon and pulled monocrystal silicon, the thermal field materials in the working room are mainly high-purity graphite and C/C composite materials, such as crucible heating body insulation tube, etc., to ensure the purity of monocrystal silicon products.


Control monocrystalline silicon using combined crucible, a crucible for C/C, for this is because the temperature of the molten silicon quartz crucible similar to quartz melting point, in 1420, soften the quartz crucible at this temperature, no load-bearing capacity, the main body of crucible is bearing external C/C but, molten silicon can not directly contact with C/C crucible, to prevent the generation of SiC, and adopted the modular crucible manufacturing high purity of C/C composites crucible process is very long, from the selection of raw materials to prepare blank production increase secret purification treatment, etc.,
The general production route of crucible preparation is listed in FIG. 2. Carbon fibres are selected according to the use requirements and prefabricated into 2-dimensional carbon fibre porous body.
After purifying the billet, densification was carried out.
Purification and graphitization can be arranged several times during the preparation of purified and high-temperature heat-treated materials. According to the material performance requirements, chemical vapour deposition (CVI) densification process can be used only, or CVI and impregnation compound densification process can be used.
For example, resin or asphalt can be impregnated to a certain density before the material is chemically vapour deposited or chemically vapour permeated;
Chemical vapour deposition of the billet to a certain density can also be carried out first, and then impregnation and densification are carried out in the middle of the carbonization and high-temperature heat treatment mainly to open the air passage on the surface of the porous billet so that the densification of the billet can continue to be effective.
Purification treatment is to remove metal impurities in the material, and the final high-temperature treatment is mainly to adjust the structure of the material to ensure the comprehensive performance of the material.

C/C crucible is the inevitable trend of technological development to replace graphite crucible. This is because the diameter of the drawn mono silicon rod is getting larger and larger, and the device is then enlarged. For example, the drawn mono silicon rod with a heat field of 30.48cm is about 81.28cm, and the outside diameter of the crucible is about?
86cm, peripheral heater is?
100cm, other supporting largest components?
In addition, the tensile, compression and interlamination shear strength of C/C composite materials are much higher than that of graphite. They can withstand greater stress, do not deform at high temperature, keep their original shape and have a long service life.

The drawing temperature of monocrystalline silicon is about 1450, and the melting point of quartz crucible is 1750. However, when the temperature reaches 1200, it begins to soften, which is mainly supported by the external graphite or C/C composite crucible.


The heater is a heating element in the periphery of the crucible. Part of the electric energy melts the raw silicon. Most of the electric energy is used for the heat preservation of molten silicon.
96 ~?
The C/C heater also has square components. Its cylindrical C/C heating element can be heated to 2500. China's Hunan Southern Boyun New Materials Co., Ltd. and Central South University have jointly studied the large diameter (152cm) C/C integral heater and insulation cylinder.


Other components C/C composite material can also be used to manufacture the thermal reflection screen (tube) upper/lower insulation cover leakproof plate bolt nut and other accessories so that the thermal field material is almost graphite and C/C composite material. Figure 4 is the insulation tube of C/C composite products and sandwich structure.