CN102977824B - High temperature binder used for binding carbon material, and preparation method and application method thereof - Google Patents

Abstract

The invention provides a high-temperature binder for binding carbon materials and a preparation and application method thereof. After chemically modifying the matrix resin with inorganic acid salts, coating and bonding carbon materials together with a curing agent, and then through curing, carbonization and other processes, a high-temperature adhesive capable of effectively connecting carbon materials is prepared. The invention has easy-to-obtain raw materials, wide selection range, simple preparation process and low cost, overcomes the shortcomings of traditional organic binders such as inability to withstand high temperatures for a long time, poor compatibility between inorganic binders and bonding substrates, etc. The carbon material interface is connected by heat-resistant and high-strength chemical bonds, thereby improving the cohesion and compactness of the adhesive layer, and overcoming mechanical connections such as riveting and screwing that easily cause carbon material stress concentration and fractures caused by friction and wear. The disadvantages also overcome the problems of poor compatibility between carbon materials and solder, unsatisfactory connection strength, difficult selection of solder, complicated process and other problems in welding technology, and realize that the bonding part has sufficient strength under high temperature conditions, while The thermal conductivity and electrical conductivity of carbon materials are not or less affected.

Description

A high-temperature binder for bonding carbon materials and its preparation and use method

technical field

The invention belongs to a high-temperature binder, and in particular relates to a high-temperature binder used for bonding carbon materials and a preparation and use method thereof.

Background technique

Carbon material is a solid with high carbon content formed by the pyrolysis of organic matter and further excluding non-carbon elements at high temperature. Carbon materials have many outstanding properties such as high specific strength, high specific modulus, good electrical and thermal conductivity, etc., so they are more and more widely used in various sectors of the national economy. What is especially important is that carbon materials have special high-temperature thermophysical properties unmatched by other materials, making them irreplaceable in the application of high-temperature and high-tech materials. For example, carbon materials are often used to prepare high-temperature components such as electrodes, heating elements, heaters, and single crystal furnace heat shields. However, the unique brittleness of carbon materials makes it inconvenient to process and produce large-sized or complex-shaped carbon products. In addition, in some occasions, it is necessary to connect carbon materials with carbon materials or metals, ceramics and other materials. However, the commonly used connection techniques, such as riveting and screwing, need to punch holes on the surface of the material, which will cause the local performance of the material to deteriorate, and it is very easy to cause fracture due to stress concentration during use, and these two connection methods It is only mechanically connected, and the contact surfaces are worn and loosened due to mutual friction, and the application is also limited. Although the welding technology can realize the overall load bearing of the connection interface, the compatibility between the inert carbon material and the solder is poor, so the connection strength is not very ideal, and there are also problems such as difficult selection of solder, complicated process and the use of equipment. There are practical issues such as special requirements. The use of adhesives to effectively connect carbon materials and their components, relying on the overall load bearing capacity of the bonding surface to improve the bearing capacity, has the advantages of simple process, convenient construction, low price, long service life, etc., and can be used according to the type of material and Changes in the use environment, etc., adjust the composition and ratio of the binder, so it can be used in a wide range.

High-temperature binders that can effectively bond carbon materials include inorganic binders and organic binders. Although inorganic binders can work at high temperatures, they are not suitable for bonding due to their low bonding strength. Joints have special requirements, and generally require special joint forms such as socket joints and groove joints. Sometimes mechanical reinforcement is required, subject to many restrictions in the connection of structural components. At the same time, since the thermal, electrical, and magnetic properties of inorganic binders are very different from those of carbon materials, the bonding parts of materials are easily damaged due to thermal stress, and the thermal and electrical conductivity of carbon materials is affected. The general use temperature of organic binders is limited to 200-300°C, which cannot meet the requirements for carbon materials to be used in high-temperature fields above 1000°C. However, the use of the residual carbon after carbonization of organic matter and the compatibility of the physical and chemical properties of the bonded carbon materials makes organic binders an important type of high-temperature binders for carbon materials. If the temperature resistance of inorganic adhesives is combined with the diverse structure and easy modification of organic adhesives to develop a composite binder, it is possible to achieve efficient bonding of carbon materials at high temperatures, and by changing the composition of the adhesive And the ratio to adjust the performance of the binder, in order to achieve good electrical and thermal conductivity after high temperature bonding, give full play to the excellent thermophysical properties of carbon materials at high temperatures, and play a positive role in promoting and expanding the further application of carbon materials effect.

With the rapid development of industries such as military, aerospace, and nuclear industries, carbon materials are being used more and more in high-temperature fields. Therefore, the research and development of new high-temperature binders for carbon materials has very important social benefits and practical significance. So far, researchers at home and abroad have made some explorations in the development of high-temperature binders for carbon materials, and achieved some research results. The Russian National Institute of Graphite Structures has developed more than 10 varieties of high-temperature binders for the production and repair of graphite, which can realize the connection of carbon-carbon composite materials, carbon and metal, etc. Alemco Corporation of the United States has developed a high-temperature adhesive with a service temperature of 2427°C and a curing temperature of 593°C. The carbon material bonded by the high-temperature adhesive prepared by Sugiro Otani of Japan using COPNA resin as raw material can maintain the bond strength above 20MPa when heated to above 2000°C, but the COPNA resin is expensive, high cost, and sticky. The junction process is complicated, and surface treatment processes such as plasma sputtering are required. The patent with the application number 99121262.2 uses resole phenolic resin as the base material and chemically modifies it by adding boron carbide to develop an organic high-temperature adhesive. The patent application No. 99123064.7 develops a high-temperature binder for bonding carbon materials by adding boron carbide and silicon dioxide to an organic resin with a residual carbon rate of 46-76% after carbonization. The patent with the application number 200610041656.3 uses tungsten phenolic resin as the matrix resin and hexamethylenetetramine as the curing agent, so that the carbon-carbon composite materials can be well connected. The patent with application number 00113381.0 uses boron-modified phenolic resin as the base material and superfine carbon black powder as the main filler to develop a high-temperature-resistant special adhesive, which overcomes the friction and wear caused by mechanical connections such as riveting and screwing. As well as the disadvantages of traditional organic adhesives that cannot withstand high temperatures for a long time, and the compatibility between inorganic adhesives and bonding substrates is poor, it ensures the various superior properties of bonded carbon materials.

To sum up, among the current high-temperature binders for carbon materials, foreign products either keep the technical ingredients secret, or use expensive resins such as COPNA; The process is cumbersome and complicated, and the quality stability is difficult to guarantee, or it needs to be modified with expensive ceramic particles such as boron carbide. In short, the cost of the developed high-temperature binders is relatively high, which is not conducive to industrialization. Therefore, it is still imminent to develop high-temperature binders for carbon materials with simple preparation process, low price and good bonding effect.

Contents of the invention

In view of the above, the purpose of the present invention is to provide a high-temperature binder for carbon materials to ensure that the bonding parts of the carbon materials have sufficient strength and good bonding effect under high temperature conditions, so that the thermal and electrical properties of the carbon materials can be improved. unaffected or less affected.

Another object of the present invention is to provide a low-cost, simple preparation process for the preparation of a high-temperature binder for carbon material bonding.

A further object of the present invention is to provide a method for using a high-temperature binder to bond carbon materials.

For realizing above-mentioned purpose, the technical scheme that the present invention takes is:

(1) A high-temperature binder for bonding carbon materials is composed of matrix resin, modifier and curing agent, and its weight ratio is 100 parts of resin, 0-25 parts of modifier, and 2 parts of curing agent. -15 copies.

Above-mentioned resin is phenolic resin, or furan resin, or furfural resin.

The above modifier is one or a combination of molybdic acid, sodium borate, boric acid, zinc borate, phosphoric acid, phosphorus oxychloride.

The above-mentioned curing agent is one or a combination of benzenesulfonyl chloride, toluenesulfonyl chloride, hexamethylenetetramine, p-toluenesulfonic acid, ethyl sulfate and petroleum sulfonic acid.

(2) A method for preparing a high-temperature binder for carbon material bonding, characterized in that, comprising the steps:

Dilute the modifying agent with industrial ethanol, methyl alcohol or acetone solvent, and its weight portion ratio is modifying agent: solvent=1: 3, under mechanical stirring, the modifying agent after dilution is gradually added in the resin, resin and modifying agent weight The part ratio is 100 parts: modifier 0-25 parts, then continue to stir and react for 30 minutes, then gradually add 2-15 parts of curing agent under stirring, and the initial high-temperature adhesive is obtained after mixing evenly.

The physical and chemical parameters of the high temperature adhesive are as follows:

Appearance: gray to brown-yellow viscous liquid

pH value: 4.0-7.5

Viscosity (20°C, Pa·s): 0.8-1.5

Density (25°C, g/cm ³ ): 1.1-1.3

Carbon residue rate: ≥65%

(3) A method for using a high-temperature binder bonded carbon material, the specific steps are:

a. Pretreatment of the bonding surface of the carbon material: smooth the bonding surface of the carbon material with fine sandpaper, clean it with ethanol and dry it;

b. Glue application: apply the initial high-temperature adhesive on both sides of the bonding surface of the carbon material, let it dry, and after the solvent evaporates, glue them together and clamp them with a clamp;

c. Curing: In the atmospheric environment, raise the initially bonded carbon material from room temperature to 100°C within half an hour, keep it warm for 30 minutes, and then raise the temperature to 180°C at a heating rate of 0.3-0.5°C/min Curing for 2 hours to form a carbon material bonding sample with a certain bonding strength;

d. Carbonization: Put the above-mentioned cured sample into a carbonization furnace protected by argon gas, and raise the temperature to 700-1700°C at a rate of 40-60°C/h for carbonization for 2-3 hours. Diffusion fully bonded the carbon material samples.

Compared with the prior art, the present invention has the following outstanding advantages and effects:

1. The raw materials of the present invention are easy to obtain, with a wide selection range, simple preparation process and low cost.

2. The present invention uses inorganic acid salts to chemically modify organic resins, which overcomes the shortcomings of traditional organic binders that cannot withstand high temperatures for a long time, poor compatibility between inorganic binders and bonding substrates, etc., and can ensure that the bonding agent and carbon Strong intermolecular forces are generated between the material interfaces, and the physical and chemical properties of the binder secondary carbon after high-temperature carbonization are similar to those of the matrix carbon material, and it is easy to form a unified whole. At the same time, the modifier reacts chemically with the resin carbonization product and the matrix carbon material to form a heat-resistant and high-strength chemical bond, thereby improving the cohesion and compactness of the adhesive layer, and achieving sufficient strength at the bonding site under high temperature conditions. The purpose of the thermal conductivity and electrical conductivity of the carbon material is not or less affected.

3. The present invention overcomes the disadvantages of mechanical connections such as riveting and screwing that easily cause stress concentration of carbon materials and fractures caused by friction and wear, and also overcomes the poor compatibility between carbon materials and solder in welding technology and the poor connection strength Problems such as unsatisfactory, difficult selection of solder, complicated process, etc., ensure that various superior properties of carbon materials can be exerted, the use is not limited, and it brings convenience to production, and has good social and economic benefits.

4. The present invention can be used not only for the connection of large-sized or complex-shaped carbon materials, but also for the adhesive repair of broken carbon products.

5. The high-temperature adhesive provided by the present invention has high high-temperature bonding strength, which reduces the loss of raw materials, thereby prolonging the service life of carbon products, improving the utilization efficiency of carbon materials, and saving costs.

Description of drawings

Fig. 1 is the infrared spectrogram of phenolic resin (a) and boric acid modified phenolic resin (b).

Fig. 2 is the thermogravimetric analysis graph of unmodified furfural resin (a), boric acid modified furfural resin (b), molybdic acid modified furfural resin (c) and zinc borate modified furfural resin (d).

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings, and the examples given are only for explaining the present invention, and are not intended to limit the scope of the present invention.

Example 1

(a) After diluting 5 parts by weight of boric acid with 15 parts by weight, industrial ethanol with a concentration of 95%, under mechanical stirring, the boric acid after dilution is gradually added in 100 parts by weight of phenolic resin, and then continue to stir for 30 minutes . Then, 8 parts by weight of petroleum sulfonic acid are gradually added therein under stirring, and the high-temperature adhesive is obtained after mixing evenly.

Fig. 1 is the infrared spectrogram of the obtained high-temperature binder boric acid modified phenolic resin and unmodified phenolic resin. It can be seen from Figure 1 that compared with the unmodified phenolic resin, the boric acid-modified phenolic resin has a stretching vibration absorption peak of the B-0 bond near 1380 cm ^-1 , indicating that the modifier boric acid and the phenolic resin undergo a chemical reaction. The reaction creates high-strength chemical bonds, which endow the modified phenolic resin with higher heat resistance.

(b) Use two carbon plates as bonding materials, grind the surface to be bonded with fine sandpaper, clean the ground carbon plate with ethanol and dry it; apply double-sided coating on the bonded surface of the cleaned and ground carbon plate Brush the high-temperature adhesive prepared in (a), and let it dry at room temperature. After the solvent volatilizes, glue them together and clamp them with a clamp; Raise the temperature to 100°C, keep it warm for 30 minutes, then raise the temperature to 180°C at a rate of 0.5°C/min, and then cure for 2 hours; finally put the above-mentioned cured sample into a carbonization furnace protected by argon, and heat it at 50°C The heating rate is raised to 1500°C for 3 hours for carbonization.

The resulting bonded carbon plate cementitious layer has higher cohesion and compactness, which can achieve sufficient strength of the bonded part under high temperature conditions, and the shear strength of the bonded joint at 180 ° C and 1500 ° C respectively reaches 16.5 MPa and 7.4MPa.

Embodiment 2-4

Examples 2-4 The preparation method of the high-temperature adhesive is basically similar to that of Example 1, except that the matrix resin is furfural resin, and the modifier is one of sodium borate, phosphoric acid, and phosphorus oxychloride. A kind, described solidifying agent is wherein a kind of of benzenesulfonyl chloride, toluenesulfonyl chloride, ethyl sulfate, described diluent is industrial methanol, and its each component and weight parts thereof are as shown in table 1:

Table 1:

The preparation method and application method of the high-temperature adhesive are similar to those in Example 1, except that a hard carbon felt is used for bonding the samples.

Fig. 2 is a thermogravimetric analysis curve of each modified high-temperature binder and its unmodified furfural resin. It can be seen from the figure that compared with the unmodified furfural resin (a), the weight loss of the modified furfural resin above 400°C is lower than that of the unmodified furfural resin, indicating that after modification, the heat resistance of the furfural resin is lower than that of the unmodified furfural resin. The performance is greatly improved and the carbon residue rate is increased.

Example 5

(a) After diluting 4 parts by weight of phosphoric acid with 12 parts by weight of industrial methanol with a concentration of 99%, under mechanical stirring, gradually add the diluted phosphoric acid in 100 parts by weight of phenolic resin, and then continue to stir and react for 30 minutes. Next, 7 parts by weight of benzenesulfonyl chloride are gradually added therein under stirring, and the high-temperature adhesive is obtained after mixing evenly.

(b) Use two carbon plates as bonding materials, grind the bonding surface of the carbon plates with fine sandpaper, clean the bonding surface of the ground carbon plates with acetone, and then dry them; after cleaning the bonding surface of the carbon plates, The high-temperature adhesive prepared in (a) is painted on both sides of the above method, and placed in the air at room temperature. After the solvent volatilizes, they are bonded together and clamped with a clamp; Rise from room temperature to 100°C within 1 hour, keep it warm for 30 minutes, then raise the temperature to 200°C at a rate of 0.4°C/min and cure for 2 hours; finally put the above cured sample into a carbonization furnace protected by argon , at a heating rate of 40°C/h to 1700°C for carbonization for 3 hours.

The resulting bonded carbon plate cementitious layer has sufficient strength, and the shear strength of the bonded joint at 200°C and 1700°C can reach 12.6MPa and 9.1MPa, respectively.

Claims (2)

1. the preparation method for the high-temperature agglomerant of the Carbon Materials that bonds, the steps include:

After the industrial alcohol that is 95% by 15 weight parts, concentration is diluted 5 weight part boric acid, under mechanical stirring, the boric acid after dilution being added to weight part gradually is in 100 parts of resol, then continue stirring reaction 30 minutes, then under agitation the mahogany acid of 8 weight parts is added wherein gradually, make high-temperature agglomerant after mixing.

2. the using method of the high-temperature agglomerant bonding Carbon Materials that prepared by claim 1, concrete steps are:

A. Carbon Materials bonding plane pre-treatment: to be bonded of Carbon Materials is polished with fine sandpaper, dry after cleaning with ethanol;

B. gluing: treat the initial high-temperature agglomerant of two-sided brushing on bonding plane at Carbon Materials, hang, after solvent evaporates, they are bonded together, use clamp;

C. solidify: in atmospheric environment, first bonding Carbon Materials is elevated to 100 ℃ from room temperature within half an hour, be incubated after 30 minutes, then be warming up to 180 ℃ of after fixing 2 hours with the temperature rise rate of 0.3-0.5 ℃/min, be formed with the Carbon Materials bonding sample of certain bonding strength;

D. charing: above-mentioned curing sample is put into to the charring furnace of argon shield, with the temperature rise rate of 40-60 ℃/h, be warming up to 700-1700 ℃ of charing 2-3 hour, the diffusion by carbonizing production between bonding surface is bonded together the Carbon Materials sample fully.

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