A highly dense carbon-ceramic barrel and its preparation method

Abstract

The present invention discloses a preparation method of a highly dense carbon-ceramic barrel. After the carbon fiber is unwound, impregnated with glue, and baked, it is wound on a mold to obtain a wound body, which is cured to obtain a barrel-shaped preform. The barrel-shaped preform is carbonized to obtain a carbonized barrel, and the carbonized barrel is subjected to reaction infiltration of silicon to obtain the carbon-ceramic barrel. The carbon-ceramic barrel provided by the present invention obtains the preform by winding. The fibers are evenly impregnated after unwinding and are arranged neatly. Moreover, the product rotates during the drying process to ensure uniform resin distribution. Compared with the traditional carbon-ceramic barrel, there are no through holes formed by needling, the porosity is low, and a large amount of solvents and small molecule substances are removed by drying before winding, realizing the high density of the product. It can isolate oxygen in the quartz crucible during various silicon material production processes, ensure the purity of the silicon material, and at the same time, the high density prevents the leakage of the silicon material.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal field components for single crystal furnaces, and particularly relates to a highly dense carbon-ceramic barrel and a preparation method thereof. Background Art

[0002] In the production processes of single crystal, polycrystal and granular silicon, the carbon-ceramic barrel is a key component in the crucible for melting silicon materials in a new type of thermal field furnace. It is required to have characteristics such as dense material, good thermal shock stability, and good chemical erosion resistance. The traditional crucibles mainly used are quartz crucibles. However, in the production process of single crystal silicon, the molten liquid silicon will react with the quartz crucible to form SiO gas, and the generated SiO gas will corrode the carbon components in the furnace, reducing the service life of related accessories. At the same time, the presence of oxygen will contaminate the silicon material, resulting in a decrease in the purity of the silicon material and seriously affecting the performance of the silicon wafer. In addition, the quartz crucible is prone to crystallization during use, and after crystallization, the crucible will crack and fail, unable to meet the requirements of long-term continuous production use. Summary of the Invention

[0003] Aiming at the deficiencies of the prior art, the first object of the present invention is to provide a preparation method of a highly dense carbon-ceramic barrel. The preparation method provided by the present invention has a short production cycle, low energy consumption, significantly reduced production cost, and is easy to realize production standardization.

[0004] The second object of the present invention is to provide the highly dense carbon-ceramic barrel prepared by the above preparation method. The carbon-ceramic barrel provided by the present invention has a high density, an open porosity of ≤1%, high purity, stable structural dimensions, a small thermal expansion coefficient, no deformation at high temperatures, good thermal shock stability, and chemical erosion resistance.

[0005] The present invention realizes the invention object by adopting the following technical solutions:

[0006] A preparation method of a highly dense carbon-ceramic barrel of the present invention includes winding carbon fibers on a mold to obtain a winding body after spreading the yarns, impregnating with glue, and baking, curing to obtain a barrel-shaped preform, carbonizing the barrel-shaped preform to obtain a carbonized barrel, and performing reaction melt infiltration of silicon on the carbonized barrel to obtain the carbon-ceramic barrel.

[0007] The carbon-ceramic barrel provided by the present invention obtains a preform by winding. The fibers are evenly impregnated after spreading the yarns, arranged neatly, and the product rotates during the drying process to ensure uniform resin distribution. Compared with the traditional carbon-ceramic barrel, there are no through holes formed by needling, the porosity is low, and a large amount of solvents and small molecule substances are removed by drying before winding, realizing the high density of the product; it can isolate oxygen in the quartz crucible during various silicon material production processes, ensure the purity of the silicon material, and at the same time the high density prevents the leakage of the silicon material.

[0008] Preferably, the carbon fiber is one of PAN-based carbon fiber and pitch-based carbon fiber.

[0009] In a preferred embodiment, during the yarn spreading process, the yarn spreading rate is controlled to be 30-50%. The inventor found that by controlling the yarn spreading rate within the scope of the present invention, different bundles of fibers can be closely and neatly arranged, thereby promoting an increase in density. If the yarn spreading rate is too high, the filaments are prone to breakage, forming defect points. Reconnecting the yarn will result in non-uniformity at the joint position, affecting airtightness. At the same time, the winding efficiency will also decrease. If it is too low, the impregnation is uneven, the internal fibers are not wrapped by the resin, and the internal gaps may not be filled with resin, affecting airtightness. At the same time, during the infiltration process, the fibers are easily silicified, affecting the mechanical properties.

[0010] In a preferred embodiment, the solid content of the sizing agent used during sizing is 40-60 wt%. The inventor found that by controlling the solid content of the sizing agent within this range, the density of the finally obtained carbon-ceramic barrel is optimal. If the solid content is too high, there will be too much resin content after sizing, and large shrinkage holes will be formed after carbonization, affecting density. If the resin content is too low, it is not sufficient to coat the fibers, and the fibers will be damaged during the infiltration process. At the same time, if the resin content is low and the solvent content is high, the solvent volatilization is not sufficient, affecting airtightness.

[0011] In a preferred embodiment, the sizing agent is composed of a resin and fine powder. The resin is selected from at least one of phenolic resin, furan resin, polycarbosilane resin, furfural ketone resin, furfural resin, epoxy resin, and pitch. The fine powder is selected from at least one of graphite powder, carbon powder, silicon carbide microfibers, and carbon nanotubes. The particle size of the fine powder is in the micron range. By adding fine powder to the resin, the density after carbonization can be improved.

[0012] Further preferably, the sizing agent, by mass fraction, is composed as follows: 60-80 parts of phenolic resin, 10-30 parts of graphite powder, and 0.1-3 parts of carbon nanotubes. The product impregnated with this formulation has a high residual carbon rate. At the same time, the carbon nanotubes increase the bonding force between the resin and the fibers, increasing the density and strength of the product.

[0013] In a preferred embodiment, the baking process is as follows: The carbon fiber obtained after sizing passes through an oven with a length of 4-15 m, preferably 5-10 m, and a temperature of 70-110 °C, preferably 100-110 °C, at a traction speed of 1-10 m / min, preferably 3-5 m / min.

[0014] The inventor found that by baking first after sizing, it can promote the premature volatilization of solvents and small-molecule substances, which can improve the density of the wound product. During the baking process, the residence time of the carbon fiber obtained after sizing in the oven can be controlled by the traction speed. Therefore, it is necessary to control the traction speed and temperature within the scope of the present invention. If the traction speed is fast, the residence time in the oven is short, and the temperature needs to be increased. Too high a temperature will cause the resin to cure prematurely, and too low a temperature will result in insufficient solvent volatilization.

[0015] In a preferred embodiment, the traction force during the winding process is 25-50 N, preferably 28-36 N, and the traction force gradient becomes smaller.

[0016] Preferably, the mold is selected from one of a wooden mold, an aluminum mold, a steel mold, and a graphite mold, and preferably a wooden mold. When using a wooden mold, demolding is not required, the cost is low, and production efficiency is improved. In the actual operation process, when using an aluminum mold, a steel mold, or a graphite mold, a mold release agent needs to be applied to the surface of the mold first to improve the demolding efficiency.

[0017] Further preferably, the mold is a mold with a solid bottom that rotates with a single-headed cantilever beam. The mold with a solid bottom that rotates with a single-headed cantilever beam can wind a pot-shaped preform, which can be made into a highly dense carbon-ceramic pot after subsequent processes. In the present invention, the carbon-ceramic pot is a carbon-ceramic barrel with an arc bottom.

[0018] Preferably, the temperature-rising program for curing is as follows: first, raise the temperature from room temperature to 180 - 200 °C at a temperature-rising rate of 3 - 10 °C / min, and finally keep the temperature constant at 180 - 200 °C for 1 - 3 h, and then cool down naturally. The inventor found that the curing program will also have a certain impact on the airtightness of the carbon-ceramic barrel. If the temperature-rising program for curing does not follow the present invention, the airtightness will be affected because the surface layer cures too fast and the internal gas cannot be released.

[0019] Preferably, during curing, the winding body is rotated at a uniform speed of 2 - 5 m / min. When curing, rotating the winding body at a uniform speed can ensure that the resin does not sag.

[0020] In the actual operation process, after curing and demolding, when cutting, the arc parts at both ends can be retained, or the arc parts at both ends can be removed and then cut into two sections, or cut into multiple sections according to the required length to prepare preforms with required dimensions and densities.

[0021] Preferably, the density of the barrel-shaped preform ≥ 1.2 g / cm 3 , preferably 1.4 - 1.6 g / cm 3 .

[0022] Preferably, the carbonization is carried out in a vacuum environment. The carbonization process is as follows: raise the temperature to 300 - 400 °C at a temperature-rising rate of 0.5 - 1 °C / min, keep the temperature for 1 - 2 h, then raise the temperature to 600 - 700 °C at a temperature-rising rate of 0.25 - 1 °C / min, keep the temperature for 1 - 2 h, and finally raise the temperature to 800 - 1000 °C at a temperature-rising rate of 0.5 - 2 °C / min, and keep the temperature for 3 - 8 h. The inventor found that when the carbonization program is controlled within the above range, the highest density of the finally obtained carbon-ceramic barrel can be achieved. If the carbonization program is unreasonable, the gas will overflow instantly during too-fast carbonization, affecting the airtightness, and if it is too slow, the production efficiency is low and the energy consumption is high.

[0023] Preferably, the density of the carbonized barrel ≥ 1.0 g / cm 3 , preferably 1.3 - 1.4 g / cm3 。

[0024] In a preferred embodiment, the barrel-shaped preform is carbonized to obtain a carbonized barrel, and then the carbonized barrel is carbon densified to obtain a carbon-carbon barrel. The carbon-carbon barrel is then subjected to reactive melt infiltration of silicon to obtain a carbon-ceramic barrel. By densifying the carbonized barrel and then performing reactive melt infiltration of silicon, the porosity of the carbon-ceramic barrel can be further reduced to less than 0.5%, further improving the density.

[0025] In the actual operation process, the carbon densification method can be introducing a carbon matrix by chemical vapor deposition or introducing a carbon matrix by impregnating resin-carbonization, and this process can adopt existing conventional technologies. Among them, chemical vapor deposition can use hydrocarbon gases such as natural gas, propylene, and methane as carbon sources, and carbon addition is carried out by chemical vapor deposition process. The deposition temperature is 850 - 1150 °C. The impregnating resin-carbonization process uses furan resin, phenolic resin, and high-temperature coal tar pitch as impregnants, and is carbonized at 800 - 1000 °C after impregnation.

[0026] In a preferred embodiment, the density of the carbon-carbon barrel is 1.2 - 1.8 g / cm 3 , preferably 1.5 - 1.7 g / cm 3 。

[0027] In a preferred embodiment, the reactive melt infiltration of silicon treatment uses silicon powder as the raw material. The reactive melt infiltration of silicon treatment is carried out in a vacuum environment. The temperature of the reactive melt infiltration of silicon treatment is 1500 °C - 2200 °C, preferably 1600 - 1800 °C, and the time of the reactive melt infiltration of silicon treatment is 1 h - 15 h.

[0028] In a preferred embodiment, the density of the carbon-ceramic barrel is 2.0 - 2.5 g / cm 3 , preferably 2.3 - 2.5 g / cm 3 , the open porosity ≤ 1%, preferably ≤ 0.7%, and further preferably ≤ 0.5%

[0029] The present invention selects the above preparation scheme, and has the following beneficial effects:

[0030] 1) The present invention selects the winding process to prepare the preform. The fibers are evenly impregnated and arranged neatly after unwinding and impregnation. And the product rotates during the drying process to ensure uniform resin distribution. Compared with the traditional carbon-ceramic barrel, there are no through holes formed by needling, the porosity is low, and a large amount of solvents and small molecule substances are removed by drying before winding, achieving high density of the product; it can isolate oxygen in the quartz crucible during various silicon material production processes, ensure the purity of the silicon material, and at the same time, the high density prevents the leakage of the silicon material.

[0031] 2) For the carbon-ceramic barrel product prepared by the present invention, the carbon fibers are in a continuous state and have excellent mechanical properties;

[0032] 3) The carbon-carbon barrel prepared by the present invention reaches 1.3 g / cm in one step3 For the above density, there is no need for a long-term densification process, the production cycle is short, and energy consumption and production costs are significantly reduced.

[0033] 4) The liquid energy of the carbon-ceramic barrel product prepared by the present invention can solve the problems of high labor costs and difficult production standardization caused by the need for a large amount of manual handling of special-shaped parts during the traditional needle punching production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] 1. Schematic diagram of the carbon-ceramic barrel with a bottom in Example 1, where Figure 1 (a) is the cross-section of the barrel with a bottom, Figure 1 (b) is the three-dimensional view of the barrel with a bottom.

[0035] 2. Figure 2 Schematic diagram of the carbon-ceramic straight barrel without a bottom in Example 2, where Figure 2 (a) is the cross-sectional view of the straight barrel, Figure 2 (b) is the three-dimensional view of the straight barrel.

[0036] 3. Figure 3 Schematic diagram of the carbon-ceramic pot with a bottom in Example 3, where Figure 3 (a) is the cross-sectional view of the carbon-ceramic pot with a bottom, Figure 3 (b) is the three-dimensional view of the carbon-ceramic pot with a bottom. DETAILED DESCRIPTION OF THE INVENTION

[0037] To more conveniently illustrate the above technical solutions of the present invention, the following detailed description will be given in combination with preferred embodiments.

[0038] Example 1

[0039] 1) T700 carbon fiber is used, the yarn spreading temperature is 100 °C, the yarn spreading angle is adjusted to make the yarn spreading rate reach 50%; it is impregnated with phenolic resin with a solid content of 60%, and 20% of graphite powder with a particle size of 5 μm is pre-mixed in the resin. After passing through an oven with a length of 10 m and a temperature of 100 °C at a traction speed of 5 m / min, it is wound around a steel mold coated with a release agent with a gradually decreasing gradient force of 30 - 36 N for 20 layers; after winding, it is put into the oven together with the mold for baking. When baking, the rotation speed of the preform is 3 m / min, and the density after curing is 1.45 g / cm 3 ; after demolding, the arc parts at both ends are retained, and it is cut from the middle part to become 2 barrels, as Figure 1 shown.

[0040] 2) The preform is placed in a carbonization furnace, evacuated to 4 mbar, and the carbonization process is from room temperature to 400 °C with a heating rate of 0.5 °C / min; 400 °C is kept constant for 1 h; 400 - 600 °C with a heating rate of 0.25 °C / min; 600 °C is kept constant for 1 h; 600 - 900 °C with a heating rate of 0.5 °C / min; a density of 1.3 g / cm is obtained3 Carbon-carbon barrel.

[0041] 3) The carbon-carbon barrel is placed in a high-temperature vacuum furnace, and the carbon-carbon blank is subjected to molten silicon infiltration treatment at a high temperature of 1900 °C to obtain a carbon-ceramic barrel with a density of 2.35 g / cm 3 , and the porosity is 1%.

[0042] Example 2:

[0043] The method is the same as that of Example 1, except that after the carbon-carbon barrel is impregnated with furan resin at 60 °C for 6 hours again, it is cured at 120 °C for 4 h under a pressure of 4 MPa, and then the carbonization process is repeated at a constant temperature of 190 °C for 5 hours, and then it enters the high-temperature vacuum furnace for molten silicon infiltration treatment. And the arc parts at both ends of the carbon-carbon barrel are removed to form a straight barrel, as Figure 2 shown. The obtained carbon-ceramic barrel has a density of 2.5 g / cm 3 , and the porosity is 0.5%.

[0044] Example 3:

[0045] Other methods are the same as those in Example 1, except that a single-ended cantilever beam type mold with a bottom is used to wind a pot with a bottom. As Figure 3 shown.

[0046] Example 4:

[0047] 1) T700 PAN-based carbon fiber is used, the yarn spreading temperature is 110 °C, and the yarn spreading angle is adjusted to make the yarn spreading rate reach 33%; it is impregnated with furan resin with a solid content of 55%, and 20% graphite powder by mass is added to the resin and stirred evenly. The particle size of the graphite powder is 3 μm, and 0.5% carbon nanotubes are added at the same time. After passing through an oven with a length of 5 m and a temperature of 110 °C at a traction speed of 3 m / min, it is wound on an aluminum mold coated with a release agent with a gradually decreasing gradient force of 28-34 N for 16 layers; after winding, it is put into the oven together with the mold for baking. During baking, the rotation speed of the preform is 4.5 m / min. After curing, it is demolded, the arc parts at both ends are removed, only the middle straight cylinder section is retained, and it is cut into two sections; the density of the preform is 1.5 g / cm 3 ;

[0048] 2) The preform is placed in a carbonization furnace and carbonized by pumping to 4 mbar. The process is as follows: the heating rate from room temperature to 400 °C is 1 °C / min; it is kept at a constant temperature of 400 °C for 1.5 h; the heating rate from 400 to 600 °C is 0.5 °C / min; it is kept at a constant temperature of 600 °C for 2 h; the heating rate from 600 to 900 °C is 1 °C / min; a carbon-carbon barrel with a density of 1.35 g / cm 3 is obtained.

[0049] 3) The carbon-carbon barrel is placed in a high-temperature vacuum furnace, and the carbon-carbon blank is subjected to molten silicon infiltration treatment at a high temperature of 1700 °C to obtain a carbon-ceramic barrel with a density of 2.3 g / cm3 , with an aperture ratio of 0.6%;

[0050] Example 5:

[0051] This method is the same as that in Example 3, except that natural gas is used as the carbon source for the carbon-carbon barrel, and carburization is carried out by chemical vapor deposition process. The deposition temperature is 1100 °C, and the deposition time is 48 h. The density reaches 1.5 g / cm 3 , and then it enters a high-temperature vacuum furnace for molten silicon infiltration treatment. The obtained carbon-ceramic barrel has a density of 2.4 g / cm3 and an aperture ratio of 0.5%.

[0052] Comparative Example 1

[0053] 1) In Comparative Example 1, the carbon fiber process is the same as that in Example 1, but the fiber is directly impregnated without unwinding.

[0054] 2) The measured density of the carbon-ceramic composite material obtained in this comparative example is 2.1 g / cm 3 , the measured mechanical properties are lower than those in Example 1, the porosity is 5%, and the densification does not meet the use requirements.

[0055] Comparative Example 2

[0056] 1) In Comparative Example 1, the carbon fiber process is the same as that in Example 1, and it is not baked before winding

[0057] 2) The measured density of the carbon-ceramic composite material obtained in this comparative example is 2.05 g / cm 3 , the measured mechanical properties are lower than those in Example 1, the porosity is 6%, and the densification does not meet the use requirements.

[0058] Comparative Example 3

[0059] 1) In Comparative Example 1, the carbon fiber process is the same as that in Example 1, but the preform is in a static state during curing.

[0060] 2) The measured density of the carbon-ceramic composite material obtained in this comparative example is 2.1 g / cm 3 , the thicknesses of the products on both sides are inconsistent, the porosity is 9%, and the densification does not meet the use requirements.

[0061] The above examples are selected examples of the present invention, but the present invention is not limited by the specific implementation content described above. Therefore, any improvements, equivalent modifications, substitutions, etc. made according to the technical points of the present invention all fall within the protection scope of the present invention.

Claims

1. A preparation method of a highly dense carbon-ceramic barrel, characterized in that: After the carbon fiber is unwound, impregnated with glue, and baked, it is wound around a mold to obtain a wound body, which is cured to obtain a barrel-shaped preform. The barrel-shaped preform is carbonized to obtain a carbonized barrel, and the carbonized barrel is subjected to reactive melt infiltration of silicon to obtain a carbon-ceramic barrel; When unwinding the yarn, the unwinding rate is controlled to be 30-50%; The solid content of the glue used during impregnation is 40-60 wt%; The baking process is as follows: the carbon fiber obtained after impregnation passes through an oven with a length of 4-15 m and a temperature of 70-110 °C at a traction speed of 1-10 m / min; When curing, the wound body is rotated at a constant speed of 2-5 m / min; The temperature increase program for curing is as follows: first, it is heated from room temperature to 180-200 °C at a heating rate of 3-10 °C / min, and finally, it is kept at a constant temperature of 180-200 °C for 1-3 h, and then it is cooled naturally; The carbonization is carried out in a vacuum environment. The carbonization process is as follows: it is heated to 300-400 °C at a heating rate of 0.5-1 °C / min, held for 1-2 h, then heated to 600-700 °C at a heating rate of 0.25-1 °C / min, held for 1-2 h, and finally heated to 800-1000 °C at a heating rate of 0.5-2 °C / min, held for 3-8 h.

2. The preparation method of a highly dense carbon-ceramic barrel according to claim 1, characterized in that: The carbon fiber is one of PAN-based carbon fiber and pitch-based carbon fiber.

3. The preparation method of a highly dense carbon-ceramic barrel according to claim 1, characterized in that: The glue is composed of resin and micro-powder. The resin is selected from at least one of phenolic resin, furan resin, polycarbosilane resin, furfural ketone resin, furfural resin, and epoxy resin. The micro-powder is selected from at least one of graphite powder, carbon powder, silicon carbide microfiber, and carbon nanotube. The particle size of the micro-powder is in the micron range.

4. The preparation method of a highly dense carbon-ceramic barrel according to claim 3, characterized in that: The glue, by mass fraction, is composed as follows: 60-80 parts of phenolic resin, 10-30 parts of graphite powder, and 0.1-3 parts of carbon nanotube.

5. The preparation method of a highly dense carbon-ceramic barrel according to claim 1 or 2, characterized in that: The traction force during the winding process is 30-50 N, and the traction force gradient becomes smaller; The mold is selected from one of a wooden mold, an aluminum mold, a steel mold, and a graphite mold.

6. The preparation method of a highly dense carbon-ceramic barrel according to claim 1 or 2, characterized in that: The density of the barrel-shaped preform ≥ 1.2 g / cm 3 .

7. The preparation method of a highly dense carbon-ceramic barrel according to claim 1 or 2, characterized in that: The density of the carbonization barrel ≥ 1.0 g / cm 3 .

8. The preparation method of a highly dense carbon-ceramic barrel according to claim 1, characterized in that: The barrel-shaped preform is carbonized to obtain a carbonized barrel, and then the carbonized barrel is carbon densified to obtain a carbon-carbon barrel. The carbon-carbon barrel is subjected to reactive melt infiltration of silicon to obtain a carbon-ceramic barrel; the density of the carbon-carbon barrel is 1.2-1.8 g / cm 3 .

9. The preparation method of a highly dense carbon-ceramic barrel according to claim 1 or 8, characterized in that: The reactive melt infiltration of silicon treatment uses silicon powder as the raw material. The reactive melt infiltration of silicon treatment is carried out in a vacuum environment. The temperature of the reactive melt infiltration of silicon treatment is 1500 °C - 2200 °C, and the time of the reactive melt infiltration of silicon treatment is 1 h - 15 h. The density of the carbon-ceramic barrel is 2.35 - 2.5 g / cm 3 , and the porosity is ≤ 1%.

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