CN112980284B - Carbon/carbon composite material surface high-infrared-emissivity coating and preparation and coating method thereof - Google Patents

Abstract

The invention relates to a high infrared emissivity coating on the surface of a carbon/carbon composite material and a preparation and coating method. The parts by mass of the components are: carbon black 9-11 parts by mass; sodium dodecyl benzene sulfonate 3-3.5 parts by mass; 1.4-1.6 parts by mass of phenolic resin; 300-350 parts by mass of absolute ethanol; 40-50 parts by mass of deionized water. The invention selects low-cost commercialized high-infrared emissivity carbon black as the main material, and uniformly sprays it on the surface of the C/C composite material by means of a suitable spraying process, and builds abundant micro-nano pores, and then uses a small amount of heat. The porous carbon black coating was reinforced by decarburization and bonded to the surface of the C/C composite material to prepare a high infrared emissivity coating with excellent interface bonding with the C/C composite material and good thermal shock resistance.

Description

A kind of carbon/carbon composite material surface high infrared emissivity coating and preparation coating method

technical field

The invention belongs to the field of infrared radiation coating materials, and relates to a high infrared emissivity coating on the surface of a carbon/carbon composite material and a preparation coating method

Background technique

Carbon fiber reinforced pyrolytic carbon matrix composite material, referred to as C/C composite material, has the characteristics of light weight, high temperature resistance and strong thermal conductivity, and is an ideal thermal management material for future high-power space vehicles. In a vacuum state, the C/C composite material conducts heat from a high temperature to a low temperature, and at the same time, the heat spreads to the space in the form of thermal radiation on the surface of the C/C composite material. Such a process of "conducting while dissipating" enables the C/C composite material to complete the thermal management of the hot-end components of the spacecraft. The thermal conductivity of C/C composites is closely related to the types of carbon fibers, the weave structure of carbon fiber preforms, and the texture of pyrolytic carbon matrix. At this stage, high thermal conductivity at room temperature greater than 630 W/(m·K) can be obtained by using pitch-based high thermal conductivity carbon fibers, improving the orientation of carbon fiber distribution, and improving the texture of the pyrolytic carbon matrix (that is, increasing the degree of graphitization). Thermally conductive C/C composites. However, most of the C/C composites for thermal conductivity have higher density, lower porosity, and more complete graphite sheet structure. Therefore, their infrared emissivity is low, and the room temperature infrared emissivity is mostly less than 0.75. In order to give full play to the thermal management and control ability of C/C composites, it is urgent to apply a heat dissipation coating with high infrared emissivity on its surface.

At present, the research on high infrared emissivity coating materials at home and abroad mainly focuses on "spinel", "cordierite", "Fe-Mn-Cu oxide" and other systems. It has a relatively high thermal expansion coefficient. If it is coated on the surface of the C/C composite material, it will not only increase the density of the C/C sample, but also generate huge interfacial stress due to thermal expansion mismatch, which will easily cause coating cracking and Extensive shedding. In addition, the infrared emissivity of such coating materials is mostly below 0.90, which still cannot meet the infrared emissivity requirements of some high-standard applications. In order to achieve good interfacial matching between infrared emitting coatings and C/C composite substrates, carbon-based coating materials, such as carbon nanotube coatings, carbon black coatings, etc., need to be developed. In comparison, carbon black has lower cost and higher yield and is often used in the preparation of infrared emitting coatings. For example, Jiang Guohua et al. used water-based resin, carbon black, dispersant, water-based leveling agent, water-based defoamer, etc. as raw materials to make a heat-dissipating coating by ball milling (Chinese Patent 102250546A); Li Chunyan et al. first prepared a modified waterproof silicone resin, and then mix it with ethyl acetate, epoxy resin, carbon black, dimethyl oxalate, azodimethylamine, hydrogenated castor oil, beryllium oxide and other raw materials to make a Waterproof and heat dissipation coating (China Patent 104152004A). To sum up, the existing carbon black high-emissivity coatings are often used in combination with resin, and the mass fraction of resin in the coating is about tens of times, or even as high as 50 times, that of carbon black. Under normal conditions, resin has lower infrared emissivity than carbon black, so the presence of high-quality resin will significantly reduce the infrared emissivity of carbon black/resin composite coating; at the same time, the resin material is hard and brittle, easy to heat Due to its expansion and other characteristics, it is very easy to fracture under the alternating high and low temperature in the space environment, and it is difficult to form a strong interface with the C/C composite material. In addition, the composition of carbon black/resin composite infrared emitting coating is relatively complex and the preparation process is cumbersome, which is not conducive to large-scale use.

SUMMARY OF THE INVENTION

technical problem to be solved

In order to avoid the deficiencies of the prior art, the present invention proposes a high infrared emissivity coating on the surface of a carbon/carbon composite material and a preparation and coating method, which is a carbon black coating on the surface of a C/C composite material and a preparation method thereof , which has the advantages of high infrared emissivity, thermal shock resistance, low cost, and convenient preparation method.

Technical solutions

A high-infrared emissivity coating on the surface of a carbon/carbon composite material, characterized in that the parts by mass of the components are: 9-11 parts by mass of carbon black; 3-3.5 parts by mass of sodium dodecylbenzene sulfonate; phenolic resin 1.4-1.6 parts by mass; 300-350 parts by mass of absolute ethanol; 40-50 parts by mass of deionized water.

A preparation method of the high infrared emissivity coating on the surface of the carbon/carbon composite material, characterized in that: placing 3-3.5 parts by mass of sodium dodecylbenzene sulfonate in 40-50 parts by mass of deionized water, ultrasonically Stir until the solution is transparent foamy water; then add 1.4-1.6 parts by mass of phenolic resin and 300-350 parts by mass of absolute ethanol and continue to sonicate for 5 minutes; finally, add carbon black in steps of 2 parts by mass each time, and ultrasonically disperse after each addition The next addition is carried out after 5 minutes, and a total of 9-11 parts by mass of carbon black is added. Finally, the carbon black is completely dispersed in the solution to obtain a coating.

A method for coating with the high infrared emissivity coating on the surface of the carbon/carbon composite material, characterized in that the steps are as follows:

Step 1: ultrasonically stir the coating for at least 20 minutes before spraying;

Step 2: Use a spray gun to spray on the surface of the C/C composite material. When spraying, the discharge port is at an angle of 30-45 degrees to the surface of the C/C composite material. The distance between the discharge port and the material surface is about 5-9cm, and the material surface is sprayed everywhere. Repeatedly until the surface is completely covered with paint evenly;

Step 3: Using chemical vapor deposition method, at 1050-1070 ℃, under the condition of methane and argon gas flow ratio of 1:8-1:10, for 13-15min, deposit an appropriate amount of heat on the surface of the sprayed coating. The carbon is decarbonized to ensure the bonding strength of the high emissivity coating to the surface of the C/C composite material in practical applications.

The prepared coating is always in an ultrasonic environment before being applied.

The prepared coating should always be kept in the ultrasonic state or ultrasonically stirred for at least 20 minutes before spraying to ensure that the carbon black is evenly dispersed before spraying

beneficial effect

A high-infrared emissivity coating on the surface of a carbon/carbon composite material and a method for preparing and coating proposed by the present invention select low-cost commercialized high-infrared emissivity carbon black as the main material, and uniformly spray it with the help of a suitable spraying process On the surface of the C/C composite material, and build rich micro-nano pores, and then use a small amount of pyrolytic carbon to reinforce the porous carbon black coating and bond it to the surface of the C/C composite material to prepare a C/C composite material. High infrared emissivity coatings with excellent interface bonding and thermal shock resistance of composite materials.

The beneficial effects of the present invention are as follows:

1. The prepared carbon black coating has excellent infrared radiation performance, and the highest emissivity that can be achieved is 0.98 in the 2-22μm band, 0.98 in the 3-5μm band, 0.97 in the 8-14μm band, and 2-15μm band. is 0.98.

2. The main raw material of the prepared coating and the C/C composite material are homogeneous materials, which have good thermal shock resistance due to their matching thermal expansion coefficients. The use of a large mass fraction of resin materials avoids coating peeling caused by mismatching thermal expansion coefficients in a vacuum thermal shock environment. The coating can withstand "800℃-room temperature" thermal shock cycles for 30 times under the protection of inert gas; the highest emissivity that can be achieved after carbon deposition is 0.95 in the 2-22μm band and 3-5μm in the band. is 0.95, the emissivity in the 8-14μm band is 0.94, and the emissivity in the 2-15μm band is 0.95.

3. As the main raw material of the coating, carbon black is sprayed on the surface of the C/C composite material. The carbon black itself has a higher emissivity than other materials, and the spraying method is used to create a loose and porous structure. This structure has a large number of interfaces. Pores are connected to the outside world, and infrared radiation electromagnetic waves entering these pores will be scattered more, increasing the probability of absorbing radiation energy. According to Kirchhoff's law, materials with high absorption rates also have high emissivity.

4. By selecting a variety of particle sizes of carbon black and adjusting the proportion of each particle size carbon black, carbon black coatings with different infrared emissivity can be prepared, because a small particle size means a larger specific surface area, and the same To provide more interfaces and sites for scattering and absorption, the specific carbon black particle size can be selected according to the application needs of the actual infrared emissivity.

5. By adjusting the parameters of the deposited pyrolytic carbon, the amount of pyrolytic carbon deposition can be controlled. application needs to be selected.

6. The cost of raw materials in this coating is low, the formula is simple, the coating is easy to prepare, and a simple spraying method can be used to spray directly and uniformly on the surface of C/C composite materials of various sizes and specifications. The operation is simple, the time-consuming is short, and it is suitable for large mass production.

Description of drawings

Fig. 1. Scanning electron microscope photograph after spraying high infrared emissivity coating step in the present invention.

Figure 2. Scanning electron microscope photograph after the step of depositing pyrolytic carbon in the present invention.

Detailed ways

The present invention will now be further described in conjunction with the embodiments and accompanying drawings:

Example 1:

A high infrared emissivity coating on the surface of a carbon/carbon composite material is prepared by the following method:

(1) 3.5 parts by mass of sodium dodecylbenzene sulfonate is placed in 40 parts by mass of deionized water, and ultrasonically stirred until the solution is in a transparent foamy water state; 1.5 parts by mass of phenolic resin is added, and 325 parts by mass of dehydrated alcohol continues Ultrasonic 5min; finally add 10 parts by mass of carbon black (particle size 10-15nm), carbon black is added step by step with 2 parts by mass each time, after each addition, ultrasonic dispersion is carried out for 5min and then the next addition is performed until the carbon black is completely in the solution. dispersion.

(2) The prepared spare coating should always be kept in the ultrasonic state or ultrasonically stirred for at least 20 minutes before spraying to ensure that the carbon black is evenly dispersed before spraying. Spray the prepared coating on the surface of the C/C composite material with a spray gun. When spraying, the outlet and the surface of the C/C composite material are at an angle of about 30-45 degrees, and the distance between the outlet and the surface of the material is about 5-9cm. All parts should be sprayed about three times until the surface is completely and evenly covered by the paint.

(3) In order to ensure the bonding strength between the high emissivity coating and the surface of the C/C composite material in practical applications, an appropriate amount of pyrolytic carbon was deposited on the surface of the sprayed coating. Using the chemical vapor deposition method, pyrolytic carbon deposition was carried out for 13-15min at 1050-1070°C and the gas flow ratio of methane and argon was 1:8-1:10.

Through measurement and calculation, the prepared high infrared emissivity coating has an emissivity of 0.98 in the 2-22μm band, 0.98 in the 3-5μm band, and 0.97 in the 8-14μm band. The emissivity in the 2-15μm band is 0.98; after the pyrolytic carbon layer is deposited, the emissivity in the 2-22μm band is 0.95, the emissivity in the 3-5μm band is 0.95, and the emissivity in the 8-14μm band is 0.94, The emissivity in the 2-15 μm band is 0.95. The coating described in this example can withstand 30 thermal shock cycles of "800°C-room temperature" under the protection of inert gas.

Example 2:

A high infrared emissivity coating on the surface of a carbon/carbon composite material is prepared by the following method:

(1) place 3.3 parts by mass of sodium dodecylbenzene sulfonate in 40 parts by mass of deionized water, and ultrasonically stir until the solution is in a transparent foamy water state; then add 1.5 parts by mass of phenolic resin, and 325 parts by mass of dehydrated alcohol continues Ultrasonic 5min; finally add 10 parts by mass of carbon black (6 parts by mass of carbon black with a particle size of 10-15nm, 4 parts by mass of carbon black with a particle size of 20-25nm), and the carbon black is added step by step with 2 parts by mass each time, and after each addition Ultrasonic dispersion is carried out for 5 minutes before the next addition. First, add carbon black with a particle size of 20-25 nm, and then add carbon black with a particle size of 10-15 nm until the carbon black is completely dispersed in the solution.

(2) The prepared spare coating should always be kept in the ultrasonic state or ultrasonically stirred for at least 20 minutes before spraying to ensure that the carbon black is evenly dispersed before spraying. Spray the prepared coating on the surface of the C/C composite material with a spray gun. When spraying, the outlet and the surface of the C/C composite material are at an angle of about 30-45 degrees, and the distance between the outlet and the surface of the material is about 5-9cm. All parts should be sprayed about three times until the surface is completely and evenly covered by the paint.

(3) In order to ensure the bonding strength between the high emissivity coating and the surface of the C/C composite material in practical applications, an appropriate amount of pyrolytic carbon was deposited on the surface of the sprayed coating. Using the chemical vapor deposition method, pyrolytic carbon deposition was carried out for 13-15min at 1050-1070°C and the gas flow ratio of methane and argon was 1:8-1:10.

Through measurement and calculation, the prepared high infrared emissivity coating has an emissivity of 0.97 in the 2-22 μm band, 0.97 in the 3-5 μm band, 0.96 in the 8-14 μm band, and 0.96 in the 8-14 μm band. The emissivity in the 2-15μm band is 0.97; after the pyrolytic carbon layer is deposited, the emissivity in the 2-22μm band is 0.94, the emissivity in the 3-5μm band is 0.94, and the emissivity in the 8-14μm band is 0.93, The emissivity in the 2-15μm band is 0.94. The coating described in this example can withstand 30 thermal shock cycles of "800°C-room temperature" under the protection of inert gas.

Example 3:

A high infrared emissivity coating on the surface of a carbon/carbon composite material is prepared by the following method:

(1) 3.2 parts by mass of sodium dodecylbenzene sulfonate is placed in 40 parts by mass of deionized water, and ultrasonically stirred until the solution is in a transparent foamy water state; 1.5 parts by mass of phenolic resin is added, and 325 parts by mass of dehydrated alcohol continues Ultrasonic 5min; finally add 10 parts by mass of carbon black (5 parts by mass of carbon black with a particle size of 10-15nm, 3 parts by mass of carbon black with a particle size of 20-25nm, and 2 parts by mass of carbon black with a particle size of 25-30nm). 2 parts by mass are added in steps. After each addition, ultrasonic dispersion is carried out for 5 minutes before the next addition. First, add carbon black with a particle size of 25-30 nm, then add carbon black with a particle size of 20-25 nm, and finally add carbon black with a particle size of 10-15 nm. until the carbon black is completely dispersed in the solution.

(2) The prepared spare coating should always be kept in the ultrasonic state or ultrasonically stirred for at least 20 minutes before spraying to ensure that the carbon black is evenly dispersed before spraying. Spray the prepared coating on the surface of the C/C composite material with a spray gun. When spraying, the outlet and the surface of the C/C composite material are at an angle of about 30-45 degrees, and the distance between the outlet and the surface of the material is about 5-9cm. All parts should be sprayed about three times until the surface is completely and evenly covered by the paint.

(3) In order to ensure the bonding strength between the high emissivity coating and the surface of the C/C composite material in practical applications, an appropriate amount of pyrolytic carbon was deposited on the surface of the sprayed coating. Using the chemical vapor deposition method, pyrolytic carbon deposition was carried out for 13-15min at 1050-1070°C and the gas flow ratio of methane and argon was 1:8-1:10.

Through measurement and calculation, the prepared high infrared emissivity coating has an emissivity of 0.95 in the 2-22 μm band, 0.95 in the 3-5 μm band, 0.95 in the 8-14 μm band, and 0.95 in the 8-14 μm band. The emissivity in the 2-15μm band is 0.95; after the pyrolytic carbon layer is deposited, the emissivity in the 2-22μm band is 0.92, the emissivity in the 3-5μm band is 0.92, and the emissivity in the 8-14μm band is 0.92, The emissivity in the 2-15μm band is 0.92. The coating described in this example can withstand 30 thermal shock cycles of "800°C-room temperature" under the protection of inert gas.

Example 4:

A high infrared emissivity coating on the surface of a carbon/carbon composite material is prepared by the following method:

(1) 3 mass parts of sodium dodecyl benzene sulfonate is placed in 40 mass parts of deionized water, ultrasonically stirred until the solution is transparent foam water; then add 1.5 mass parts of phenolic resin, 325 mass parts of dehydrated alcohol continue Ultrasonic 5min; finally add 10 parts by mass of carbon black (particle size 20-25nm), carbon black is added step by step with 2 parts by mass each time, after each addition, ultrasonic dispersion is carried out for 5min and then the next addition is performed until the carbon black is completely in the solution. dispersion.

(2) The prepared spare coating should always be kept in the ultrasonic state or ultrasonically stirred for at least 20 minutes before spraying to ensure that the carbon black is evenly dispersed before spraying. The prepared paint is sprayed on the surface of the C/C composite material with a spray gun. When spraying, the outlet and the surface of the C/C composite material are at an angle of about 30-45 degrees, and the distance between the outlet and the surface of the material is about 5-9cm. It should be sprayed about three times until the surface is completely and evenly covered by the paint.

(3) In order to ensure the bonding strength between the high emissivity coating and the surface of the C/C composite material in practical applications, an appropriate amount of pyrolytic carbon was deposited on the surface of the sprayed coating. Using the chemical vapor deposition method, pyrolytic carbon deposition was carried out for 13-15min at 1050-1070°C and the gas flow ratio of methane and argon was 1:8-1:10.

Through measurement and calculation, the prepared high infrared emissivity coating has an emissivity of 0.93 in the 2-22 μm band, 0.93 in the 3-5 μm band, 0.93 in the 8-14 μm band, and 0.93 in the 8-14 μm band. The emissivity in the 2-15μm band is 0.93; after the pyrolytic carbon layer is deposited, the emissivity in the 2-22μm band is 0.90, the emissivity in the 3-5μm band is 0.90, and the emissivity in the 8-14μm band is 0.90, The emissivity in the 2-15 μm band is 0.90. The coating described in this example can withstand 30 thermal shock cycles of "800°C-room temperature" under the protection of inert gas.

Claims (4)

1. a high infrared emissivity coating on the surface of a carbon/carbon composite material, characterized in that the mass fraction of components is: carbon black 9-11 mass parts; sodium dodecyl benzene sulfonate 3-3.5 mass parts; phenolic 1.4-1.6 parts by mass of resin; 300-350 parts by mass of anhydrous ethanol; 40-50 parts by mass of deionized water; the carbon black is selected from nanoscale. 2. a preparation method of the described carbon/carbon composite material surface high infrared emissivity coating of claim 1, is characterized in that: 3-3.5 mass parts of sodium dodecylbenzene sulfonate are placed in 40-50 mass parts to remove In ionized water, ultrasonically stir until the solution is transparent foamy water; then add 1.4-1.6 parts by mass of phenolic resin and 300-350 parts by mass of absolute ethanol and continue to ultrasonicate for 5 minutes; finally add carbon black in steps of 2 parts by mass each time After the addition, ultrasonic dispersion is carried out for 5 minutes, and then the next addition is performed. A total of 9-11 parts by mass of carbon black is added, and finally the carbon black is completely dispersed in the solution to obtain a coating. 3. a coating method that adopts the coating prepared by the described preparation method of claim 2, is characterized in that step is as follows: Step 1: ultrasonically stir the paint for at least 20 minutes before spraying; Step 2: Use a spray gun to spray on the surface of the C/C composite material. When spraying, the discharge port is at an angle of 30-45 degrees to the surface of the C/C composite material. The distance between the discharge port and the surface of the material is 5-9cm. over and over until the surface is completely and evenly covered by the paint; Step 3: Using chemical vapor deposition method, at 1050-1070 ℃, under the condition of methane and argon gas flow ratio of 1:8-1:10, for 13-15min, deposit an appropriate amount of heat on the surface of the sprayed coating. Decarbonize. 4 . The coating method according to claim 3 , wherein the coating is always in an ultrasonic environment before coating. 5 .

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