Carbon / carbon rigid insulation blanket and method of making same

Abstract

This invention discloses a carbon / carbon rigid thermal insulation felt and its preparation method. The method involves screening machined carbon powder (below 10 mesh), suspending agent, binder, and mesh, dispersing them in water in a certain proportion and stirring evenly. Then, the mixture is poured into a mold, pressed, and thermoformed. The resulting carbon / carbon rigid thermal insulation felt blank is then subjected to carbonization, high temperature, and other treatments to obtain the carbon / carbon rigid thermal insulation felt.

Description

Technical Field

[0001] This invention belongs to the field of rigid thermal insulation felt technology, specifically relating to a carbon / carbon rigid thermal insulation felt and its preparation method. Background Technology

[0002] As the basic material for semiconductor materials, the production of materials such as monocrystalline silicon and polycrystalline silicon requires a harsh ultra-high temperature thermal field, which traditional thermal insulation materials cannot meet, resulting in drawbacks such as unstable thermal field, poor corrosion resistance, and large expansion coefficient.

[0003] Carbon / carbon rigid insulation felt is a new type of thermal insulation material and an important material for manufacturing crystalline silicon. Produced from short fiber scraps and carbon-carbon product machining waste, carbon / carbon rigid insulation felt achieves low cost while improving production efficiency. The utilization of waste machining carbon powder solves waste disposal problems and fully leverages the advantages of this process. This process produces carbon / carbon rigid insulation felt primarily used in various high-temperature furnaces and thermal field materials in metallurgical materials, semiconductor materials, and the new energy photovoltaic industry. The product has extremely high design flexibility and is widely applicable to the needs of alloy sintering furnaces, single-crystal silicon furnaces, vacuum smelting furnaces, vacuum heat treatment furnaces, and vapor deposition furnaces.

[0004] However, there are still some problems with the current production process of carbon / carbon rigid insulation felt. For example, the current process involves bonding and pressing thin carbon fiber felts layer by layer, which can easily lead to insufficient bonding strength between the carbon / carbon rigid insulation felt layers and cracking and delamination. Because the thin carbon fiber felts are bonded together with adhesive, there are problems with uneven density after molding, resulting in low thermal conductivity and insulation performance. Summary of the Invention

[0005] Current production processes for carbon / carbon rigid insulation felt suffer from insufficient interlayer bonding strength, cracking, and delamination. Furthermore, the use of adhesives between thin carbon fiber felts leads to uneven density after molding, resulting in poor thermal conductivity and insulation performance. This invention provides a carbon / carbon rigid insulation felt and its preparation method. The resulting carbon / carbon rigid insulation felt features a randomized wadding design, a simple and convenient process, minimal environmental impact, and significant contribution to environmental protection through the recycling of waste turning materials.

[0006] Technical principle of the invention:

[0007] The present invention discloses a method for preparing carbon / carbon rigid insulation felt using a wet molding process. The method involves screening machined carbon powder of less than 10 mesh, purifying it at 2000°C, adding suspending agent, binder, and mesh, dispersing it in water in a certain proportion, stirring evenly, and then letting it stand for more than 8 hours to defoam. The powder is then poured into a mold, pressurized, and thermosetting. The resulting carbon / carbon rigid insulation felt blank is then subjected to carbonization, high temperature, and other treatments to obtain the carbon / carbon rigid insulation felt.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] Carbon powder with a mesh size of less than 10 is purified at a high temperature of 2000℃. Suspension agent, binder, mesh, etc. are dispersed in water in a certain proportion and stirred evenly. After standing for more than 8 hours, defoaming treatment is carried out. Then, after each layer of mesh is laid, a 10cm thick slurry is poured, and then another layer of mesh is laid. The above steps are repeated until the preset thickness is achieved.

[0010] A method for preparing carbon / carbon rigid thermal insulation felt includes the following steps:

[0011] 1) Mix the turning material carbon powder, suspending agent, binder and water in a mass ratio of 10:0.05:0.2:1 thoroughly to obtain a uniformly dispersed mixture;

[0012] The suspending agent is selected from one or more of methylcellulose, hydroxyethylcellulose, and carboxymethylcellulose, and the mixture is in any proportion.

[0013] The binder is selected from polyvinyl alcohol;

[0014] 2) Lay the mesh on the bottom of the molding mold according to the design, and then pour the uniformly dispersed mixture obtained in the previous step into the molding mold. Separate the middle with a thickness of 5mm, fill the small areas by weight, pour and mold, and then heat to 220℃ to solidify and mold. Demold to obtain carbon / carbon rigid thermal insulation felt mold blank.

[0015] 3) The obtained carbon / carbon rigid insulation felt preform is carbonized under vacuum or inert atmosphere at a carbonization temperature of 950℃, followed by high-temperature purification treatment at 2200℃, and then further processed mechanically to obtain the carbon / carbon rigid insulation felt. This invention also relates to a method for preparing carbon / carbon rigid insulation felt. Using the above-mentioned method, the carbon / carbon rigid insulation felt obtained has the following technical indicators:

[0016] The bulk density is ≤0.20 g / cm³. 3The compressive strength is ≥0.4MPa, the flexural strength is 2-3.5MPa, the thermal conductivity is ≤0.25W / mk, the coefficient of thermal expansion (10﹣6 / ℃) is <1, the ash content is 50-150ppm, and the processing temperature is 2200℃.

[0017] Furthermore, the particle size of the machined carbon powder is below 10 mesh, and it has undergone high-temperature purification treatment at 2000℃. The uniformity of carbon powder dispersion in aqueous solution directly affects the performance and density of carbon / carbon rigid insulation felt.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. The present invention provides a carbon-carbon rigid thermal insulation felt, which is made by fully dispersing carbon powder, suspending agent, binder, etc. in an aqueous solution, and preparing a slurry with controllable density by wet molding process, laying a mesh in the middle, and filling with weight-divided fillers to form a low thermal conductivity carbon / carbon rigid thermal insulation felt.

[0020] 2. The method for preparing carbon-carbon rigid thermal insulation felt according to the present invention, in the process of preparing carbon / carbon rigid thermal insulation felt, the lower the density of the suspending agent solution (the suspending agent, carbon powder and binder are mixed and dissolved in water and stirred to obtain a slurry with a density between 1.4 and 1.5), the higher the density of the carbon / carbon rigid thermal insulation felt after carbonization, because more carbon powder is absorbed in the fixed pores, and the amount of residual carbon increases after carbonization, thus increasing the quality of the carbon / carbon rigid thermal insulation felt.

[0021] 3. The method for preparing carbon / carbon rigid thermal insulation felt according to the present invention involves carbonizing the carbon / carbon rigid thermal insulation felt preform, which has a certain shrinkage in volume. The finished carbon / carbon rigid thermal insulation felt is obtained through wet molding, reinforcement by random wadding structure and netting, and subsequent mechanical processing. Attached Figure Description

[0022] Figure 1 This is a physical image of the carbon / carbon rigid thermal insulation felt prepared in Experimental Example 1 of this invention;

[0023] Figure 2 This is a physical image of the carbon / carbon rigid thermal insulation felt prepared in Experimental Example 2 of this invention. Detailed Implementation

[0024] The present invention will be further described in detail below through embodiments, but these embodiments should not be considered as limiting the present invention.

[0025] Example 1:

[0026] A method for preparing carbon / carbon rigid thermal insulation felt includes the following steps:

[0027] 1) Mix the turning material carbon powder, suspending agent, binder and water in a mass ratio of 10:0.05:0.2:1, stir thoroughly and mix evenly to obtain a uniformly dispersed mixture;

[0028] The particle size of the turning material carbon powder is below 10 mesh, and it has been purified at a high temperature of 2000℃.

[0029] The suspending agent is selected from methylcellulose;

[0030] The binder is selected from polyvinyl alcohol;

[0031] 2) Lay the mesh on the bottom of the molding mold according to the design, and then pour the uniformly dispersed mixture obtained in the previous step into the molding mold. Separate the middle parts with a thickness of 5mm, fill the parts by weight in small areas, pour and mold, and then heat to 220℃ for curing and molding. Demold to obtain a uniform carbon / carbon rigid thermal insulation felt mold blank.

[0032] 3) The obtained carbon / carbon rigid insulation felt preform is carbonized in a vacuum or inert atmosphere at a temperature of 950°C, purified at a temperature of 2200°C, and then further processed by mechanical processing to obtain carbon / carbon rigid insulation felt.

[0033] This carbon / carbon rigid insulation felt has the following technical specifications:

[0034]

[0035]

[0036] Example 2:

[0037] A method for preparing carbon / carbon rigid thermal insulation felt differs from Example 1 in that the suspending agent in step 1) is selected from hydroxyethyl cellulose, while the rest is the same as in Example 1.

[0038] This carbon / carbon rigid insulation felt has the following technical specifications:

[0039] Performance items unit Parameter value Bulk density <![CDATA[g / cm 3 ]]> 0.19 compressive strength MPa 0.5 flexural strength MPa 2.0 thermal conductivity W / mk 0.22 coefficient of thermal expansion 10﹣6 / ℃ ﹤1 Ash ppm 150 Processing temperature ℃ 2200

[0040] Example 3:

[0041] A method for preparing carbon / carbon rigid thermal insulation felt differs from Example 1 in that the suspending agent in step 1) is selected from an equal mass mixture of methylcellulose, hydroxyethylcellulose, and carboxymethylcellulose, while the rest is the same as in Example 1.

[0042] This carbon / carbon rigid insulation felt has the following technical specifications:

[0043]

[0044]

[0045] Comparative Example 1:

[0046] The existing method for preparing carbon / carbon rigid insulation felt specifically includes the following steps:

[0047] 1) Traditional thermal insulation felt requires purchasing carbon fiber soft felt first and then cutting it to the size according to the blank size;

[0048] 2) Then impregnate the cut carbon fiber soft felt in resin, and then use a spin dryer to spin off the excess resin.

[0049] 3) Lay the spun-dry carbon fiber felt flat on the template and repeat the layering until the designed thickness is reached;

[0050] 4) Push the template of the laid carbon fiber soft felt into a hot press to solidify and form a carbon fiber thermal insulation hard felt blank;

[0051] 5) After carbonization at 950℃ and purification at 2000℃, it is processed and shaped.

[0052] This carbon / carbon rigid insulation felt has the following technical specifications:

[0053] Performance items unit Parameter value Bulk density <![CDATA[g / cm 3 ]]> 0.3-0.35 compressive strength MPa ≤0.3 flexural strength MPa 1.5-2 thermal conductivity W / mk 0.5-1.5 coefficient of thermal expansion 10﹣6 / ℃ 1.5-2 Ash ppm 150-300 Processing temperature ℃ 1800-2000

[0054] Comparative Example 2:

[0055] The preparation method of carbon / carbon rigid thermal insulation felt differs from that of Example 1 in that, in step 1), the suspending agent, carbon powder and binder are mixed and dissolved in water and stirred to obtain a slurry with a density between 1.8 and 2.0. The rest is the same as in Example 1.

[0056] This carbon / carbon rigid insulation felt has the following technical specifications:

[0057]

[0058]

[0059] The results show that:

[0060] 1. By comparing the preparation processes of Examples 1-3 and Comparative Example 1, the Examples, compared with Comparative Example 1, utilize machined carbon powder and mesh laying, reducing the use of carbon fiber soft felt, greatly reducing costs and shortening the production cycle.

[0061] 2. The traditional carbon fiber soft felt represented by Comparative Example 1 needs to be cut to size according to the blank, which generates excess scrap and increases production costs; while the carbon / carbon thermal insulation rigid felt of the embodiment is formed by filling the slurry into a set mold, which does not generate excess scrap.

[0062] 3. The traditional carbon fiber soft felt represented by Comparative Example 1 is laid by impregnating carbon fiber soft felt with resin, spinning it dry, and then layering it. It is prone to interlayer cracking and delamination. In contrast, the carbon / carbon rigid insulation felt of the embodiment is laid by filling the slurry in sections by weight and adding a mesh, which has a stronger overall integrity, is more uniform, and is less prone to delamination and cracking.

[0063] 4. The carbon / carbon rigid insulation felt in the embodiment is integrally molded by filling with slurry and laying with a mesh, resulting in better compressive and bending resistance, as well as better coefficient of thermal expansion and thermal conductivity.

[0064] 5. By comparing the technical indicators of the carbon / carbon rigid insulation felt in Examples 1-3 and Comparative Example 1, it can be seen that the carbon / carbon rigid insulation felt prepared by the method of Examples 1-3 has low density, high thermal insulation efficiency, low thermal conductivity, high temperature resistance, corrosion resistance, short production cycle, can be quickly molded and processed, has a wide range of applicable raw materials, thus has low cost and extremely high product performance designability.

[0065] 6. By comparing the technical indicators of the carbon / carbon rigid insulation felt in Examples 1-3 and Comparative Example 2, mainly the comparison of insulation performance, it is found that even a slight difference in parameters results in a significant difference in performance. This indicates that the carbon / carbon rigid insulation felt produced by this process has advantages such as low cost, short production cycle, avoidance of delamination problems, oxidation resistance, corrosion resistance, low thermal conductivity, and superior insulation performance.

[0066] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. Various process solutions that are not substantially different from the concept of the present invention are all within the scope of protection of the present invention.

Claims

1. A method of making carbon / carbon rigid insulation batts, characterised by: Includes the following steps: 1) Mix the turning material carbon powder, suspending agent, binder and water in a mass fraction ratio of 10:0.05:0.2:1 thoroughly to obtain a uniformly dispersed mixture; The particle size of the turning material carbon powder is below 10 mesh, and it has been purified at a high temperature of 2000℃. The suspending agent is selected from one or more of methylcellulose, hydroxyethylcellulose, and carboxymethylcellulose, and the mixture is in any proportion. The binder is selected from polyvinyl alcohol; 2) Lay the mesh on the bottom of the molding mold according to the design, and then pour the uniformly dispersed mixture obtained in the previous step into the molding mold. Separate the middle with a thickness of 5mm, fill the small areas by weight, pour and shape, and then heat to 220℃ for curing and molding. Demold to obtain carbon / carbon rigid thermal insulation felt mold blank. 3) The obtained carbon / carbon rigid insulation felt preform is carbonized in a vacuum or inert atmosphere at a carbonization temperature of 950℃, followed by high-temperature purification treatment at 2200℃, and then further processed by machining to obtain the carbon / carbon rigid insulation felt. The carbon / carbon rigid insulation felt has the following technical indicators: The bulk density is ≤0.20 g / cm³. 3 Compressive strength ≥ 0.4 MPa, flexural strength 2-3.5 MPa, thermal conductivity ≤ 0.25 W / mK, coefficient of thermal expansion < 1 × 10⁻⁶ -6 / ℃, ash content 50-150 ppm, processing temperature 2200℃.

2. A carbon / carbon rigid insulation blanket characterized by: The carbon / carbon rigid thermal insulation felt is prepared using the method described in claim 1.

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