A method for producing a carbon-containing refractory material

Abstract

The application relates to a preparation method of a carbon-containing refractory material, and belongs to the technical field of refractory materials.The preparation method comprises the following steps: acidizing treatment is conducted on carbon nanotubes to obtain carboxyl carbon nanotubes; poly-silazane and a catalyst are added into a carboxyl carbon nanotube dispersion liquid to conduct amidation reaction under an inert atmosphere, and modified carbon nanotubes are obtained; refractory material powder, the modified carbon nanotubes and a bonding agent are mixed in proportion, and then are pressed into a shape, and are solidified at 100 DEG C-120 DEG C to obtain a shaped sample; the shaped sample is placed in an inert atmosphere, is heated to 1200 DEG C-1400 DEG C, and is kept at a temperature for 2h-4h to obtain the carbon-containing refractory material.The carboxyl carbon nanotubes are subjected to amidation reaction with the poly-silazane, the poly-silazane can be grafted on the surface of the carbon nanotubes, the dispersibility of the carbon nanotubes is improved, meanwhile, the poly-silazane can be pyrolyzed and converted into a ceramic coating in the firing process of the refractory material, the ceramic coating can protect the structure of the carbon nanotubes and prevent the carbon nanotubes from being oxidized, and therefore the performance of the refractory material is improved.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials technology, specifically relating to a method for preparing carbon-containing refractory materials. Background Technology

[0002] Carbon-containing refractories play an important role in the metallurgical industry, especially in steelmaking, where they are widely used in key components such as ladle linings and continuous casting components. Traditional carbon-containing refractories mostly use graphite as their carbon source and are classified into high-carbon and low-carbon refractories based on the amount of graphite. Generally, carbon-containing refractories with a graphite content of no more than 8% are considered low-carbon refractories, while those with a graphite content of more than 8% are considered high-carbon refractories.

[0003] The introduction of graphite can increase the thermal shock stability and erosion resistance of refractory products. However, due to inherent drawbacks, graphite reacts with oxygen in the air at high temperatures to generate COx gas, leading to increased porosity and reduced erosion resistance, thus shortening the service life of the refractory. Simply reducing the graphite content would significantly decrease the thermal shock stability and erosion resistance of the refractory. Carbon nanotubes offer better mechanical and thermal properties than graphite, and can improve the thermal shock stability and erosion resistance of low-carbon refractories while reducing the overall carbon content. However, the addition of large amounts of carbon nanotubes can cause agglomeration, directly reducing the mechanical properties of the refractory. Furthermore, some carbon nanotubes may be consumed during firing due to oxidation or structural transformation. Therefore, improvements are needed. Summary of the Invention

[0004] In view of the above situation and to overcome at least some of the defects of the prior art, the present invention provides a method for preparing carbon-containing refractory materials.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] This invention provides a method for preparing a carbon-containing refractory material, characterized in that it includes:

[0007] Carbon nanotubes were acidified to obtain carboxylated carbon nanotubes. Polysilazane and a catalyst were added to the carboxylated carbon nanotube dispersion, and an amidation reaction was carried out under an inert atmosphere to obtain modified carbon nanotubes.

[0008] The refractory powder, the modified carbon nanotubes, and the binder are mixed in proportion, pressed into shape, and cured at 100℃-120℃ to obtain the molded sample.

[0009] The shaped sample is placed under an inert atmosphere, heated to 1200-1400 DEG C, and held for 2-4 hours to obtain the carbon-containing refractory material.

[0010] In some embodiments, the conditions of the amidation reaction include: a temperature of 130-140 DEG C, a time of 20-30 hours; and / or, the inert atmosphere used in the amidation reaction is at least one of a nitrogen atmosphere, an argon atmosphere, and a helium atmosphere.

[0011] In some embodiments, the mass ratio of the carboxyl carbon nanotube to the polysilazane is 1:2-3.

[0012] In some embodiments, the mass ratio of the carboxyl carbon nanotube to the catalyst is 1:1-1.5; and / or, the catalyst comprises one or more of a metal chloride salt, a metal nitrate salt, and a metal oxide.

[0013] In some embodiments, the method for preparing the carboxyl carbon nanotube dispersion includes: dispersing carboxyl carbon nanotubes in N,N-dimethylformamide, and ultrasonically treating for 1-2 hours at a power of 200-300 W.

[0014] In some embodiments, the ratio of the refractory material powder, the modified carbon nanotube, and the bonding agent is 80:(1-8):(3-5).

[0015] In some embodiments, the bonding agent comprises one or more of an epoxy resin bonding agent, a polyurethane bonding agent, and a phenolic resin bonding agent.

[0016] In some embodiments, the acidification treatment comprises:

[0017] The carbon nanotubes are added to concentrated nitric acid, ultrasonically dispersed, heated to 100-110 DEG C, washed, and dried to obtain the carboxyl carbon nanotubes.

[0018] In some embodiments, the concentration of the concentrated nitric acid is 65-70%, and the amount of carbon nanotubes added to the concentrated nitric acid is 15-20 g / L.

[0019] In some embodiments, the refractory material powder comprises one or more of fused white corundum, alumina, silica, aluminum powder, and silicon powder.

[0020] The present application has the following beneficial effects:

[0021] Carboxyl groups can be introduced on the surface of carbon nanotubes by acidification treatment to improve the reactivity of carbon nanotubes, and the carboxyl carbon nanotubes can be subjected to amidation reaction with polysilazane to graft polysilazane on the surface of carbon nanotubes, thereby improving the dispersibility of carbon nanotubes, and the polysilazane can be pyrolyzed into a ceramic coating during the sintering process of the refractory material, and the ceramic coating can protect the structure of the carbon nanotubes and prevent the oxidation of the carbon nanotubes, thereby improving the performance of the refractory material. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by one of ordinary skill in the art. In addition, any method and material similar or equivalent to those described herein can be used in the present application. The preferred implementation methods and materials described herein are only used for demonstration, but cannot limit the content of the present application.

[0024] In view of the deficiencies in the prior art mentioned in the background, the embodiments of the present application propose a preparation method of carbon-containing refractory material, comprising:

[0025] Carboxyl carbon nanotubes are obtained by acidizing treatment on carbon nanotubes, and polysilazane and a catalyst are added to the carboxyl carbon nanotube dispersion liquid to perform amidation reaction under inert atmosphere to obtain modified carbon nanotubes;

[0026] The refractory material powder, modified carbon nanotubes and adhesive are mixed in proportion, and then pressed into a shaped sample, which is cured at 100-120 DEG C to obtain a shaped sample;

[0027] The shaped sample is placed in an inert atmosphere, heated to 1200-1400 DEG C, and kept for 2-4 hours to obtain a carbon-containing refractory material.

[0028] Due to its unique structure, carbon nanotubes have excellent mechanical and thermal properties, and as fillers added to refractory materials, they can improve the thermal shock stability and erosion resistance of low-carbon refractory materials while reducing the overall carbon content of the material. However, the addition of a large amount of carbon nanotubes will cause agglomeration, and the carbon nanotubes will be consumed due to oxidation or structural transformation during the sintering process of the refractory material.

[0029] Carboxyl groups can be introduced on the surface of carbon nanotubes by acidification treatment to improve the reactivity of carbon nanotubes. The carboxyl carbon nanotubes can be subjected to amidation reaction with polysilazane to graft polysilazane on the surface of carbon nanotubes, thereby improving the dispersibility of carbon nanotubes. At the same time, the polysilazane can be pyrolyzed into a ceramic coating during the firing process of the refractory material, which can protect the structure of carbon nanotubes and prevent the oxidation of carbon nanotubes, thereby improving the performance of the refractory material.

[0030] In some embodiments, the conditions of the amidation reaction include a temperature of 130-140°C and a time of 20-30h. Controlling the temperature of the amidation reaction at 130-140°C can improve the reaction rate and facilitate the amidation reaction. Controlling the time at 20-30h can ensure that the amidation reaction is fully carried out and improve the yield of the modified carbon nanotubes.

[0031] In some embodiments, the inert atmosphere used in the amidation reaction is at least one of nitrogen atmosphere, argon atmosphere and helium atmosphere. Using an inert atmosphere can prevent impurities (such as oxygen and moisture) in the reaction system from having a negative impact on the reaction, thereby ensuring the smooth progress of the reaction.

[0032] In some embodiments, the mass ratio of carboxyl carbon nanotubes to polysilazane is 1:2-3. By setting the mass ratio of carboxyl carbon nanotubes to polysilazane to 1:2-3, the surface of carbon nanotubes can be fully grafted with polysilazane, thereby increasing the grafting amount of polysilazane and fully protecting carbon nanotubes during the firing process.

[0033] In some embodiments, the mass ratio of carboxyl carbon nanotubes to catalyst is 1:1-1.5. The catalyst can reduce the activation energy of the reaction, accelerate the reaction process and improve the reaction efficiency. By setting the mass ratio of carboxyl carbon nanotubes to catalyst to 1:1-1.5, the reaction efficiency of the amidation reaction can be improved, while avoiding the accumulation of excessive catalyst affecting the catalytic efficiency.

[0034] In some embodiments, the catalyst includes one or more of metal-based chloride salt, metal-based nitrate salt and metal oxide. Metal-based chloride salt, metal-based nitrate salt and metal oxide have good catalytic effect on the amidation reaction between carboxyl carbon nanotubes and polysilazane, and zinc chloride is preferred.

[0035] In some embodiments, the preparation method of the carboxyl carbon nanotube dispersion includes dispersing carboxyl carbon nanotubes in N,N-dimethylformamide and subjecting to ultrasonic treatment for 1-2h at a power of 200-300W. Ultrasonic treatment can break the interaction between carboxyl carbon nanotubes, promote the dispersion of carboxyl carbon nanotubes and facilitate the preparation of carboxyl carbon nanotube dispersion.

[0036] In some embodiments, the ratio of the refractory material powder, the modified carbon nanotubes and the adhesive is 80:(1-8):(3-5). Among them, the refractory powder has a high proportion as the main component, the proportion of the modified carbon nanotubes can be adjusted according to the needs, but too low cannot fully play its reinforcing effect, too high increases the forming difficulty, and the adhesive can tightly combine the refractory material powder and the modified carbon nanotubes together.

[0037] In some embodiments, the adhesive includes one or more of epoxy resin adhesive, polyurethane adhesive and phenolic resin adhesive. Epoxy resin adhesive, polyurethane adhesive and phenolic resin adhesive all have good adhesion and can provide good interfacial bonding force to improve the performance of the refractory material.

[0038] In some embodiments, the acidification treatment includes: adding carbon nanotubes into concentrated nitric acid, ultrasonic dispersion, heating to 100-110 DEG C, washing, drying, to obtain carboxyl carbon nanotubes. Concentrated nitric acid can oxidize the carbon nanotubes, thereby introducing hydroxyl groups on the surface of the carbon nanotubes. It should be noted that the reaction temperature is 100-110 DEG C, and the temperature is too low, the reaction efficiency is too low, and the temperature is too high, which will damage the structure of the carbon nanotubes.

[0039] In some embodiments, the concentration of concentrated nitric acid is 65-70%, and the addition amount of carbon nanotubes in concentrated nitric acid is 15-20 g / L. The concentration of concentrated nitric acid has a direct influence on its oxidation ability, and too high concentration will lead to too violent reaction, which will damage the structure of the carbon nanotubes, and too low concentration will result in poor oxidation effect. Therefore, the concentration of concentrated nitric acid is set to 65-70%.

[0040] In some embodiments, the refractory material powder includes one or more of electrically fused white corundum, alumina, silicon oxide, aluminum powder and silicon powder. Electrically fused white corundum has high melting point, high hardness, high wear resistance and good chemical stability, which can improve the thermal shock resistance and corrosion resistance of the refractory material, alumina and silicon oxide have high melting point and good chemical stability, mainly as a refractory filler, aluminum powder mainly as an additive can promote sintering, and the addition of silicon powder can improve the density and strength of the refractory material.

[0041] The application will be further described in the following specific embodiments.

[0042] The experimental methods in the following examples are all conventional methods unless otherwise specified; the test materials used in the following examples are all purchased from commercial channels unless otherwise specified.

[0043] The refractory material powder used in the following examples includes the following components by weight: electrically fused white corundum 60 parts, alumina 10 parts, silicon oxide 10 parts, aluminum powder 2 parts, silicon powder 3 parts.

[0044] Example 1

[0045] The carbon nanotubes were added to concentrated nitric acid with a concentration of 65%, and the amount of carbon nanotubes added to the concentrated nitric acid was 15 g / L. The carbon nanotubes were ultrasonically dispersed, heated to 100°C, washed, and dried to obtain carboxyl carbon nanotubes.

[0046] The carboxyl carbon nanotubes were dispersed in N,N-dimethylformamide and ultrasonically treated for 1 h at a power of 200 W to obtain a carboxyl carbon nanotube dispersion;

[0047] Polydimethylsiloxane and zinc chloride were added to the carboxyl carbon nanotube dispersion, the mass ratio of carboxyl carbon nanotubes to polydimethylsiloxane was 1:2, and the mass ratio of carboxyl carbon nanotubes to zinc chloride was 1:1. An amidation reaction was carried out under a nitrogen atmosphere at a reaction temperature of 130°C for 20 h to obtain modified carbon nanotubes.

[0048] The refractory material powder, modified carbon nanotubes, and phenolic resin adhesive were mixed in a proportion of 80:1:3, and then pressed and molded. The molded sample was cured at 100°C to obtain a molded sample.

[0049] The molded sample was placed in a nitrogen atmosphere and heated to 1200°C for 2 h to obtain a carbon-containing refractory material.

[0050] Example 2

[0051] The carbon nanotubes were added to concentrated nitric acid with a concentration of 70%, and the amount of carbon nanotubes added to the concentrated nitric acid was 20 g / L. The carbon nanotubes were ultrasonically dispersed, heated to 110°C, washed, and dried to obtain carboxyl carbon nanotubes.

[0052] The carboxyl carbon nanotubes were dispersed in N,N-dimethylformamide and ultrasonically treated for 2 h at a power of 300 W to obtain a carboxyl carbon nanotube dispersion.

[0053] Polydimethylsiloxane and zinc chloride were added to the carboxyl carbon nanotube dispersion, the mass ratio of carboxyl carbon nanotubes to polydimethylsiloxane was 1:3, and the mass ratio of carboxyl carbon nanotubes to zinc chloride was 1:1.5. An amidation reaction was carried out under a nitrogen atmosphere at a reaction temperature of 140°C for 30 h to obtain modified carbon nanotubes.

[0054] The refractory material powder, modified carbon nanotubes, and epoxy resin adhesive were mixed in a proportion of 80:8:5, and then pressed and molded. The molded sample was cured at 120°C to obtain a molded sample.

[0055] The shaped sample was placed under nitrogen atmosphere, heated to 1400℃, and kept for 4h to obtain the carbon-containing refractory material.

[0056] Example 3

[0057] Consistent with Example 1, except that the mass ratio of carboxyl carbon nanotubes to polysilazane was 1:2.5.

[0058] Example 4

[0059] Consistent with Example 1, except that the mass ratio of carboxyl carbon nanotubes to polysilazane was 1:3.

[0060] Example 5

[0061] Consistent with Example 1, except that the ratio of refractory material powder, modified carbon nanotubes and binder was 80:3:3.

[0062] Example 6

[0063] Consistent with Example 1, except that the ratio of refractory material powder, modified carbon nanotubes and binder was 80:5:3.

[0064] Example 7

[0065] Consistent with Example 1, except that the ratio of refractory material powder, modified carbon nanotubes and binder was 80:6:3.

[0066] Example 8

[0067] Consistent with Example 1, except that the ratio of refractory material powder, modified carbon nanotubes and binder was 80:7:3.

[0068] Comparative Example 1

[0069] Consistent with Example 1, except that carbon nanotubes were used instead of modified carbon nanotubes in the refractory material.

[0070] The refractory materials prepared in Examples 1-8 and Comparative Example 1 were tested for performance, and the test contents were as follows:

[0071] Bending strength test:

[0072] A WDW-50 universal testing machine was used to measure the maximum load that the sample could withstand at the time of fracture using a three-point bending method. The size of the sample was 10mm x 10mm x 40mm, the span was set to 32mm during the experiment, and the loading rate was 1mm / min.

[0073] Thermal shock stability test:

[0074] The test method refers to GB / T30873-2014 "Thermal shock resistance test method", and is specifically as follows: the heating furnace is preheated to 1100 DEG C and kept for 15 min, then the sample to be tested is quickly moved into the furnace, after the furnace temperature rises to 1100 DEG C, it is kept for 30 min, the heated sample is cooled by compressed air for 5 min, then it is put into the furnace at 1100 DEG C, and the above process is repeated for 3 times, after the sample is completely cooled, its bending strength is measured, and the strength retention rate is calculated, the strength retention rate = strength after thermal shock / strength before thermal shock x 100%.

[0075] Antioxidant test:

[0076] The test method refers to GB / T13244-1991 "Carbon-containing refractory material antioxidant test method", and is specifically as follows: the sample is placed in the furnace, heated to 1400 DEG C at a specified heating rate, kept for 2 h, and then cut into two halves after cooling to room temperature, and the decarburization layer thickness is measured, wherein the shape of the sample is a cube with a side length of 50 mm.

[0077] The test results are shown in Table 1.

[0078] Table 1 Test results

[0079]

[0080] As can be seen from Table 1, compared with Comparative Example 1 using carbon nanotubes, Examples 1-8 using modified carbon nanotubes have different degrees of improvement in bending strength, thermal shock stability and antioxidant property, so it can be seen that the addition of modified carbon nanotubes can improve the performance of the refractory material, and at the beginning, with the increase of the amount of modified carbon nanotubes, the bending strength, thermal shock stability and antioxidant property of the refractory material are improved to a certain extent, and the improvement amplitude is less with the increase of the amount of modified carbon nanotubes, therefore, considering the performance and cost, the mass ratio of the refractory material powder to the modified carbon nanotubes is more appropriate at 80:6-8.

[0081] The above examples are only used to illustrate the technical solutions of the present application and not to limit it, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the purpose and scope of the present application, and all of them should be covered in the protection scope of the present application.

Claims

1. A method for producing a carbon-containing refractory material, characterized in that, The application relates to a preparation method of a carbon-containing refractory material. The acidification treatment is carried out on carbon nanotubes to obtain carboxyl carbon nanotubes, polysilazane and a catalyst zinc chloride are added into a carboxyl carbon nanotube dispersion liquid, and an amidation reaction is carried out under an inert atmosphere to obtain modified carbon nanotubes; wherein the temperature of the amidation reaction is 130-140 DEG C, and the time is 20-30 hours; the mass ratio of the carboxyl carbon nanotubes to the polysilazane is 1:2-3; The refractory material powder, the modified carbon nanotubes and a binder are mixed in proportion, and then are pressed and formed, and are cured at 100-120 DEG C to obtain a formed sample; the proportion of the refractory material powder, the modified carbon nanotubes and the binder is 80:(1-8):(3-5); the refractory material powder is composed of fused white corundum, alumina, silicon oxide, aluminum powder and silicon powder; The formed sample is placed under an inert atmosphere, is heated to 1200-1400 DEG C, and is kept at the temperature for 2-4 hours to obtain the carbon-containing refractory material.

2. The production method according to claim 1, characterized by, The inert atmosphere used in the amidation reaction is at least one of a nitrogen atmosphere, an argon atmosphere and a helium atmosphere.

3. The production method according to claim 1, characterized by, The mass ratio of the carboxyl carbon nanotubes to the catalyst is 1:1-1.

5.

4. The method of claim 1, wherein, The preparation method of the carboxyl carbon nanotube dispersion liquid comprises the following steps: dispersing carboxyl carbon nanotubes in N,N-dimethylformamide, and carrying out ultrasonic treatment; the ultrasonic treatment time is 1-2 hours, and the power is 200-300 W.

5. The preparation method according to claim 1, characterized in that, The binder comprises one or more of a mixture of an epoxy resin binder, a polyurethane binder and a phenolic resin binder.

6. The method of claim 1, wherein, The acidification treatment comprises the following steps: The carbon nanotubes are added into concentrated nitric acid, are ultrasonically dispersed, are heated to 100-110 DEG C, are washed, and are dried to obtain the carboxyl carbon nanotubes.

7. The production method according to claim 6, wherein The concentration of the concentrated nitric acid is 65-70%, and the addition amount of the carbon nanotubes in the concentrated nitric acid is 15-20 g / L.

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