A kind of carbon/carbon polycrystalline silicon hydrogenation furnace thermoscreen and preparation method thereof
Technical field
The present invention relates to a kind of polysilicon hydrogenation furnace with thermoscreen and preparation method thereof, especially relate to a kind of carbon/carbon compound material polysilicon hydrogenation furnace thermoscreen and preparation method thereof.
Background technology
Polysilicon chip, cost low advantage low with production capacity height, energy consumption occupies the solar cell dominant position in the photovoltaic industry.At present, produce in the polysilicon product, hydrogenation furnace is to produce the by product SiCl that produces in the polysilicon product process in the recycle system
4With H
2Reaction generates SiHCl
3The visual plant that raw material utilizes again.In the hydrogenation furnace, industrial tail gas is SiCl
4Usually adopt bottom inflow or side air inlet, 5~7 kilograms of furnace pressures, temperature is more than 1200 ℃ and H
2React, and a blow-on just needs non-stop run more than 2000 hours, its thermoscreen is the heat insulating member of heating element periphery, for a constant temperature zone is provided in the burner hearth.Therefore, require the heat-proof quality of thermoscreen good, corrosion-resistant and wash away, material purity height can not pollute polysilicon product.
At present, the carbon/carbon compound material thermoscreen has appearred on the market, a kind of " monocrystalline silicon draw machines and the polysilicon smelting furnace preparation method of thermal field charcoal/charcoal thermoscreen " disclosed as Chinese patent ZL200610043184.5, it adopts three way structure thermoscreen precast body, matrix only is asphalt carbon and resin charcoal, and through the purification process of 2000~2500 ℃ chlorine or freonll-11, this preparation method's cycle is long, the cost height, and the thermoscreen etch resistant properties of making is poor; Chinese patent application discloses " a kind of polysilicon hydrogenation furnace preparation method of charcoal/charcoal thermoscreen " for No. 200910022540.9, this method adopts three way structure thermoscreen precast body, matrix is pyrolytic carbon and asphalt carbon or resin carbon, this preparation method has a CVD coating in that the thermoscreen precast body is surface-coated, etch resistant properties increases, but still is difficult to resist the abominable production environment of hydrogenation furnace.In addition, all adopt mechanical workout product all surface in above-mentioned two kinds of hydrogenation furnace thermoscreen preparation process and be shaped, so the cutwork amount is big, the starting material input amount is big, and cost is higher.
Russia's preparation polysilicon hydrogenation furnace adopts charcoal cloth lamination to twine precast body with charcoal/charcoal thermoscreen, the densification of pure chemistry gas-phase permeation technology, and top coat is handled.This preparation method's production cycle is long, and efficient is low, the cost height.The about 1000mm of its product diameter, dimensions is little, can not satisfy the demand of hydrogenation furnace large size development gradually.
The polysilicon hydrogenation furnace of the western Cree Inc. of Germany preparation adopts no latitude cloth lamination precast body with charcoal/charcoal thermoscreen, adds with bituminizing to be pressed into rectangular flat plate, adopts the anistree splicing of bolt hoop.The thermoscreen stopping property of this method preparation is poor, can't bear big pressure in the hydrogenation furnace, and installation difficulty is big, damages easily.
Summary of the invention
The object of the present invention is to provide a kind of heat-proof quality good, corrosion-resistant, anti-washing away, good seal performance, easy for installation, long service life, carbon/carbon polycrystalline silicon hydrogenation furnace thermoscreen that raw materials consumption is few in process of production, production cost is low and preparation method thereof.
The present invention's carbon/carbon compound material polysilicon hydrogenation furnace thermoscreen is made of thermoscreen body and silicon carbide protective layer, and described thermoscreen body is class " sandwich is a sandwich " structure, and extexine and internal skin are that density is more than or equal to 1.2 g/cm
3Three-dimension integrally acupuncture charcoal felt or the density of charcoal cloth form, the middle layer is that density is less than or equal to 0.25 g/cm
3The density of charcoal felt form; Silicon carbide protective layer is coated on the thermoscreen body surface.Each layer thickness is determined according to the heat-insulating property index request that the user proposes.
The present invention's carbon/carbon compound material polysilicon hydrogenation furnace thermoscreen adopts following method to be prepared from:
(1) requires to make thermoscreen steel fetal membrane according to size;
(2) thermoscreen body blank preparation:
There are the carbon fiber sheet of thermosetting resin or the whole felt of three-dimensional acupuncture to be wound in from level to level on the steel fetal membrane with evenly brushing or infiltrating, when the thickness of winding adheres to specification, are the internal skin; Then twine to have soaked into from level to level the soft charcoal of thermosetting resin felt is arranged, the thickness that twines is the middle layer when adhering to specification, twine the carbon fiber sheet or the whole felt of three-dimensional acupuncture of heat of emersion thermosetting resin more from level to level, the integral thickness that twines equals to be when size requires extexine, finish winding working procedure, utilize the external force compacting then, form the thermoscreen body blank of class " sandwich is sandwich " structure;
(3) solidification treatment: the thermoscreen body blank that step (2) makes is put into baking oven together with the steel fetal membrane, be cured at 150~340 ℃ and handled 300~600 minutes, get thermoscreen body base substrate;
(4) charing is handled: the thermoscreen body base substrate of the band steel fetal membrane that step (3) is made is put into charring furnace, carries out charing at 600~800 ℃ and handles 20~60 hours, makes resin be converted into resin carbon, formation carbon/carbon compound material thermoscreen body work in-process;
(5) take off the steel fetal membrane: the carbon/carbon compound material thermoscreen body work in-process that step (3) is made take off the steel fetal membrane, clean out;
(6) the CVD density is handled: carbon/carbon compound material thermoscreen body work in-process are put into chemical vapor deposition stove, carry out the CVD density with carbon-source gas, depositing time is 40~100 hours, reaches 〉=0.30g/cm to global density
3
(7) machining: step (6) gained thermoscreen body work in-process are carried out the turning or the boring of both ends of the surface according to the drawing technical requirements, be processed into the thermoscreen body of desired size;
(8) silicon carbide protective layer lining:
1. contain silicon coating at thermoscreen body surfaces externally and internally and end face coating, coat-thickness is 20 ~ 50 μ m;
2. the thermoscreen that coating is finished dried in the air 3~5 hours, placed baking oven again, in 140~200 ℃ of insulations oven dry in 1.0~3.5 hours;
3. the thermoscreen with oven dry places chemical vapor deposition stove, is 900 ℃ ~ 1500 ℃ in temperature, deposits 10 ~ 60 hours with carbon-source gas, makes the coating of thermoscreen surfaces externally and internally, end face and groove, hole surface be converted into the hard coat of silicon carbide;
(9) high temperature purification treatment: the thermoscreen that is coated with the hard coat of silicon carbide that step (8) is made places 1800~2200 ℃ of High Temperature Furnaces Heating Apparatuss, is incubated 4~10 hours, removes detrimental impurity, and form original position and generate silicon carbide protective layer.
Described carbon fiber sheet can be 3K, 6K or 12K carbon fiber sheet.
Described three-dimension integrally charcoal felt can not have latitude cloth and the acupuncture of net tire forms by the big tow charcoal of 12K fiber, and no latitude cloth accounts for gross weight 65%~85% in the charcoal felt, and all the other are the net tire.
Described thermosetting resin can be resol or furane resin or pitch.
The described silicon coating that contains can be made up of thermosetting resin, silica flour and Graphite Powder 99, and three's mass ratio is: thermosetting resin: silica flour: Graphite Powder 99=1:0.1 ~ 0.6:0.05 ~ 0.3.
The carbon-source gas that described CVD density processing and silicon carbide hard layer carry out in the CVD processing can be propylene, propane or Sweet natural gas.
The diameter of described carbon/carbon polycrystalline silicon hydrogenation furnace thermoscreen is 1000~1810mm.
The thermal conductivity of described carbon/carbon polycrystalline silicon hydrogenation furnace thermoscreen is 0.5~20W/mK.
The present invention compared with prior art has following advantage:
(1) carbon/carbon polycrystalline silicon hydrogenation furnace thermoscreen body construction of the present invention is " sandwich is sandwich " structure, extexine and internal skin by density more than or equal to 1.2 g/cm
3Three-dimension integrally acupuncture charcoal felt or charcoal cloth, the middle layer of thermoscreen is less than or equal to 0.25 g/cm by density
3The charcoal felt, this structure not only has excellent heat insulation property, also has higher physical strength;
(2) adopt near-net-shape technology (less, do not have cutting) to make, raw materials consumption reduces more than 90%, greatly reduce production cost, so product price is lower than like product;
(3) whole thickening technology mainly adopts chemical gaseous phase depositing process, be that carbon base body mainly is made up of the RESEARCH OF PYROCARBON that the high temperature pyrolysis mode obtains, and product carries out high temperature purification treatment at last, thus the ash content of product low (≤100ppm), satisfy the high purity polycrystalline silicon production requirement fully;
(4) at production environment abominable in the hydrogenation furnace, product surface adopts anticorrosive and antiscour is handled, and the coat of silicon carbide that original position forms has improved product corrosion resistance nature and abrasion resistance energy, has prolonged the work-ing life of thermoscreen greatly.
Description of drawings
Fig. 1 is a carbon/carbon compound material polysilicon hydrogenation furnace thermoscreen embodiment body construction synoptic diagram of the present invention.
Embodiment
The invention will be further described below in conjunction with embodiment.
Embodiment 1
This carbon/carbon compound material polysilicon hydrogenation furnace thermoscreen embodiment is that diameter 1595mm, high 727mm, thickness are the carbon/carbon compound material polysilicon hydrogenation furnace thermoscreen of 130mm; Be made of thermoscreen body and silicon carbide protective layer, described thermoscreen body construction is class " sandwich is sandwich " structure referring to Fig. 1, and extexine 1 and internal skin 3 form for the density of 6K carbon cloth, and the middle layer of thermoscreen 2 forms for the density of soft charcoal felt; Silicon carbide protective layer is coated on the thermoscreen body surface.
Its preparation method is as follows:
(1) the thermoscreen steel fetal membrane of making diameter 1338mm, a high 800mm;
(2) with behind the even brushing furane resin of 6K carbon cloth, to be wound on the steel fetal membrane from level to level, when thickness to be wound reaches 5mm, then twine the soft charcoal felt that has soaked into furane resin from level to level, when thickness to be wound reaches 1593mm, will evenly be coated with the carbon cloth that is brushed with furane resin again and be wound in from level to level on the soft charcoal felt, when integral thickness to be wound equals 1595mm, finish winding working procedure, utilize the external force compacting then, form the thermoscreen body blank of class " sandwich is sandwich " structure;
(3) the thermoscreen body blank that step (3) is made is put into baking oven together with the steel fetal membrane and is cured processing, and the treatment time is 420 minutes, and solidification value is 200 ℃, gets thermoscreen body base substrate;
(4) the thermoscreen body base substrate of the band steel fetal membrane that step (3) is made is put into charring furnace and is carried out charing and handle, make resin change resin carbon into, form carbon/carbon compound material thermoscreen body work in-process, carbonization time is 35 hours, and the charing top temperature is 680 ℃;
(5) the thermoscreen body work in-process after the charing are taken off the steel fetal membrane, clean out;
(6) the CVD density is handled: the thermoscreen body work in-process that step (5) is taken off the steel fetal membrane are put into chemical vapor deposition stove and are carried out the CVD density, and carbon-source gas adopts propane, and depositing time is 60 hours, and global density reaches 0.31g/cm
3
(7) machining: the thermoscreen work in-process of step (6) gained density are carried out flat both ends of the surface and open seam according to the design paper technical requirements, be processed into the thermoscreen body of desired shape and size;
(8) silicon carbide protective layer lining:
1. contain silicon coating at thermoscreen body surfaces externally and internally and end coating, containing silicon coating is that 1:0.15:0.28 forms by furane resin, silica flour and Graphite Powder 99 mass ratio, and its coat-thickness is 25 μ m;
2. the thermoscreen that coating is finished dried in the air 4 hours, placed baking oven again, in 180 ℃ of insulations oven dry in 2 hours;
3. the thermoscreen with oven dry places chemical vapor deposition stove, and the deposition top temperature is 1000 ℃, and carbon-source gas adopts propane, deposits 20 hours;
(9) high temperature purification treatment: the thermoscreen of step is placed 2200 ℃ of High Temperature Furnaces Heating Apparatuss, be incubated 6 hours and remove detrimental impurity, form original position and generate silicon carbide protective layer.
Embodiment 2
(1) the thermoscreen steel fetal membrane of making diameter 1680mm, a high 950mm;
(2) with behind the even brushing furane resin of carbon cloth, to be wound on the steel fetal membrane from level to level, when thickness to be wound reaches 4mm, then twine the soft charcoal felt that has soaked into furane resin from level to level, when thickness to be wound reaches 1808mm, will evenly be coated with the carbon cloth that is brushed with furane resin again and be wound in from level to level on the soft charcoal felt, when integral thickness to be wound equals 1810mm, finish winding working procedure, utilize the external force compacting then, form the thermoscreen body blank of class " sandwich is sandwich " structure;
(3) the thermoscreen body blank that step (3) is made is put into baking oven together with the steel fetal membrane and is cured processing, and the treatment time is 320 minutes, and solidification value is 180 ℃, gets thermoscreen body base substrate;
(4) the thermoscreen body base substrate of the band steel fetal membrane that step (3) is made is put into charring furnace and is carried out charing and handle, make resin change resin carbon into, form carbon/carbon compound material thermoscreen body work in-process, carbonization time is 25 hours, and the charing top temperature is 650 ℃;
(5) the thermoscreen body work in-process after the charing are taken off the steel fetal membrane, clean out;
(6) the CVD density is handled: the thermoscreen body work in-process that step (5) is taken off the steel fetal membrane are put into chemical vapor deposition stove and are carried out the CVD density, and carbon-source gas adopts propane, and depositing time is 45 hours, and global density reaches 0.30g/cm
3
(7) machining: the thermoscreen work in-process of step (6) gained density are carried out flat both ends of the surface and open seam according to the design paper technical requirements, be processed into the thermoscreen body of desired shape and size;
(8) silicon carbide protective layer lining:
1. contain silicon coating at thermoscreen surfaces externally and internally and end coating, containing silicon coating is that 1:0.15:0.28 forms by furane resin, silica flour and Graphite Powder 99 mass ratio, and its coat-thickness is 20 μ m;
2. the thermoscreen that coating is finished dried in the air 3.5 hours, placed baking oven again, in 160 ℃ of insulations oven dry in 1.5 hours;
3. the thermoscreen with oven dry places chemical vapor deposition stove, and the deposition top temperature is 990 ℃, and carbon-source gas adopts propane, deposits 18 hours;
(9) high temperature purification treatment: the thermoscreen of step is placed 2100 ℃ of High Temperature Furnaces Heating Apparatuss, be incubated 4 hours and remove detrimental impurity, form original position and generate silicon carbide protective layer.