The polycrystalline silicon ingot or induction heating furnace for purification is the structure of the graphite heater, and belongs to the technical field of design and manufacture of the structure of the heater of the polycrystalline silicon ingot furnace or the purification furnace .
The high current on the heater forms a circular flow. The heater used must ensure that the current flow is reliable and smooth. If the junction is connected, it may cause local high contact resistance, which may cause fire and other damage to the heater. Or cause local over-temperature will affect the safety of polycrystalline ingot crucible, so there must be a very reliable method to use combined graphite
Heater, this combination heater is composed of 8 graphite sheets, and every 4 graphite sheets form a square graphite ring.
The edge junction is processed into a zigzag shape. After the four pieces are combined, each two pieces are fixed with carbon fiber screws, between the upper and lower graphite rings
The handover is processed into a stepped shape where the tables are combined with each other. After the processing is completed, all the handovers applied to the graphite ring using graphite slurry
Carbon fiber surface and the transfer surface of the screw, after a slow heating to 1200 deg.] C, the graphite ring integrally sintered, the upper and lower graphite ring combined and used together, the combination of the heater to form a square ,, vertical handover is a natural graphite ring junction , Not graphite
When one of them is broken, it can be replaced separately. When the induction heating furnace has an upper heating design, a graphite sheet is added on the upper part of the combined heater to form a combined heater with an upper heating plate. Graphite sheet uses high-density electrode graphite or three high stone
Ink to process to ensure its service life.
At present, the weight of practical silicon ingots has reached 270-450Kg , and the side length of the heater can reach about 900mm . The combined heater is composed of four graphite sheets, which will significantly reduce the cost and make it easier to obtain the source. The structure diagram of the combined heater is shown in Figure 1 . Reducing the contact resistance at the graphite sheet junction to form a good ring-shaped induced current is the core purpose of the present invention
Where, the design increases the contact area and reliability of the graphite sheet, and is coated with graphite slurry on the contact surface, after high temperature sintering to
Form better contacts.
In order to strengthen the structural strength of the combined crucible, graphite slurry is used at the junction of the screw and screw hole and the graphite plate. After sintering, the electrical contact and the structural firmness are increased. In addition, the contact surface of the carbon fiber screw is not directly in contact with the atmosphere in the furnace. Long-term use can prevent the opportunity of oxidation and prevent damage to the heater due to poor contact at the junction and the phenomenon of fire caused by the presence of large current. The upper and lower heating graphite rings can also be integrally composed of four plates. If considering the cost and local replaceability, it is more reasonable to divide the upper and lower heating graphite rings. Combined heater can provide good heating and good
Electrical contact to meet the requirements of long-term stability of ingot and purification.
Figure 1 is the overall layout of the invention in the furnace
Figure 2 is a structural diagram of graphite heating sheet
Figure 3 is the structural diagram of the upper and lower graphite heating rings
Or a polycrystalline silicon ingot was purified by induction heating furnace DETAILED DESCRIPTION:
The electrode graphite is used to make a combined low-cost square heater. The structure of the graphite plate includes
Upper Yang tooth plate  and its side view  , Upper Yin tooth plate  and its side view  , using two pieces of each to form an upper graphite ring  , using the lower Yang tooth plate [II] ] And the lower female tooth plate  two pieces each combined into a lower graphite ring  . The male teeth on the male tooth plate have rib holes  (perpendicular to the surface of the plate) through the plate, and the rib holes  (parallel to the surface) on the female tooth groove of the female tooth plate, use Carbon fiber screws are used to connect these two boards. The upper and lower graphite rings are combined into a heater   , and the top heating graphite plate  is included when there is an upper heating ring . The exterior of the combined heater is closely attached to the insulation layer  , and the exterior of the insulation layer is a square induction coil made of copper tubes   . The crucible  is placed in a heater in the center of the furnace  to melt the polycrystalline silicon material, and then the crucible is slowly lowered to form a silicon ingot by directional solidification. The experiment has been carried out in the ingot furnace and purification furnace of 160-200KG polycrystalline silicon ingot, and good results of ingot and purification have been obtained. This program is officially used in production
It can be used in the ingot furnace for casting silicon ingots above 450KG . The thickness and height of the graphite plate are unchanged, mainly to increase the outside of the heater
Increasing the size and number of screws can be a carbon fiber reinforcement to