Carbon / carbon composite material with continuous W fiber grid reinforced W-Cu coating and preparation method

Abstract

The invention discloses a carbon / carbon composite material with a continuous W fiber grid reinforced W-Cu coating and a preparation method of the carbon / carbon composite material, and belongs to the technical field of ultrahigh-temperature composite materials. According to the carbon / carbon composite material with the continuous W fiber grid reinforced W-Cu coating, the surface of a matrix carbon / carbon composite material is coated with the continuous W fiber grid reinforced W-Cu coating; the continuous W fiber grid reinforced W-Cu coating is composed of a W-Cu coating and a plurality of layers of continuous W fiber grids which are distributed in the W-Cu coating and arranged in an up-down laminated mode, and the continuous W fiber grids play a role in reinforcing phases. The W-Cu coating is composed of a W particle framework and Cu distributed in gaps of the W particle framework, the problem that a traditional coating is insufficient in obdurability is solved, and the high-toughness ablation-resistant coating on the surface of the carbon / carbon composite material is prepared.

Description

Technical Field

[0001] The present invention belongs to the technical field of ultra-high temperature composite materials, and particularly relates to a carbon / carbon composite material with a continuous W fiber grid-reinforced W-Cu coating and a preparation method thereof. Background Art

[0002] Fiber-reinforced composite materials used for hot-end components of aerospace aircraft usually need to face harsh service environments, such as ultra-high service temperatures, high-speed gas / particle flow erosion, etc. Conventional materials are prone to performance degradation and structural damage under the coupled action of multiple loads. In order to balance lightweight design and high-temperature load-bearing capacity, carbon / carbon composite materials with low density and excellent high-temperature mechanical properties are mainly used at present. However, carbon / carbon composite materials have strong high-temperature oxidation sensitivity and weak erosion resistance, and are severely ablated in the above service environment, easily leading to strength degradation and structural failure.

[0003] Constructing a protective coating on the surface of carbon / carbon composite materials can isolate the internal carbon / carbon composite materials from the external oxygen-containing atmosphere and effectively improve the oxidation and ablation resistance of carbon / carbon composite materials. Literature 1 "D. Hu, Q. Fu, Z. Dong, et al., Design of ablation resistant Zr-Ta-O-C composite coating for service above 2400℃ [J]. Corrosion Science, 2022, 200: 110221." uses plasma spraying technology to design and prepare a Zr-Ta-O-C composite ceramic coating on the surface of carbon / carbon composite materials. After oxyacetylene flame (heat flux density 4.2 MW / m 2)The thickness change rate is only -1.67 μm / s after ablation for 30 s. However, ceramic materials are brittle, and huge thermal stresses are likely to be generated inside the materials when the temperature changes rapidly. In this case, the ceramic coating is prone to cracking, and the protective performance declines significantly. The excellent ductility of metal materials can effectively release the thermal stress during the thermal shock process. In Document 2, “Y. Guo, H. Y. Xie, Z. R. Jiang, et al., Mechanical Properties and Thermal Shock Resistance of Rhenium Coating in Iridium / Rhenium / Carbon-carbon Composites, Procedia Engineering, 2015, 99: 1407-1414.”, a Re coating was prepared on the surface of carbon / carbon composites. No obvious cracks were observed in the coated specimens after 10 thermal cycles of 800-2000 °C in a vacuum atmosphere. However, when the ablation environment is accompanied by external impacts such as strong airflows / particle flows, relying solely on the toughness of the material itself is not enough, and additional toughening treatment of the material is required. In Document 3, a coating-matrix modified integrated C / C-W-Cu composite material and a preparation method provided by a Chinese invention patent with the publication number of CN118596662A. The composite material includes a surface coating, a modified matrix layer, and a matrix layer arranged in sequence from top to bottom; the surface coating is a W-Cu composite coating, the modified matrix layer is a modified C / C-W-Cu matrix layer, and the matrix layer is a C / C matrix layer. Although there is a W-Cu composite coating on the surface of the composite material as a protective layer, which improves the particle impact resistance of the composite material, the coating is mainly composed of stacked W particles, and its toughness is difficult to guarantee. Summary of the Invention

[0004] Aiming at the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a carbon / carbon composite material with a continuous W fiber grid-reinforced W-Cu coating (W f / W-Cu coating) and a preparation method thereof, to solve the problem of insufficient strength and toughness of traditional coatings, and to realize the preparation of a high-strength, tough and ablation-resistant coating on the surface of carbon / carbon composite materials.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] The present invention provides a carbon / carbon composite material with a continuous W fiber grid-reinforced W-Cu coating, and the continuous W fiber grid-reinforced W-Cu coating is coated on the surface of the matrix carbon / carbon composite material; the continuous W fiber grid-reinforced W-Cu coating is composed of a W-Cu coating and several layers of continuous W fiber grids arranged in an upper and lower laminated manner inside the W-Cu coating, and the continuous W fiber grids act as reinforcing phases; the W-Cu coating is composed of a W particle skeleton and Cu distributed in the gaps between the W particle skeletons.

[0007] In one embodiment, the continuous W fiber grid-reinforced W-Cu coating is tightly combined with the matrix carbon / carbon composite material without defects such as cracks and pores, and a pinning structure is formed at the interface between the continuous W fiber grid-reinforced W-Cu coating and the matrix carbon / carbon composite material, and there is a composition gradient.

[0008] In one embodiment, the continuous W fiber grids are embedded inside the W-Cu coating and sinter with the W particle skeletons in the surrounding W-Cu coating.

[0009] In one embodiment, the toughness and plasticity of the carbon / carbon composite material with the continuous W fiber grid-reinforced W-Cu coating are improved, and the failure mode of the three-point bending test shows plastic fracture.

[0010] The present invention also provides a preparation method for a carbon / carbon composite material with a continuous W fiber grid-reinforced W-Cu coating, comprising the following steps:

[0011] Pre-treat the matrix carbon / carbon composite material and the continuous W fiber grids respectively;

[0012] Prepare a slurry;

[0013] Immerse the continuous W fiber grids in the slurry, and at the same time, use a brush to dip the slurry and apply a W pre-coating on the surface of the matrix carbon / carbon composite material. After applying a certain thickness of the W pre-coating, paste the continuous W fiber grids impregnated with the slurry on the surface of the matrix carbon / carbon composite material coated with the W pre-coating to form a layer of W f / W pre-coating; dry the W f / W pre-coating, then apply the slurry again and paste the continuous W fiber grids impregnated with the slurry and dry. Repeat the above steps several times until the W f / W pre-coating reaches the target thickness and the specified number of continuous W fiber grid layers to obtain a carbon / carbon composite material coated with a pre-coating;

[0014] Mix NaCl powder, KCl powder, WO3 powder and Cu powder to obtain an infiltration powder; use the infiltration powder to coat the carbon / carbon composite material coated with the pre-coating, and then perform heat treatment to obtain a carbon / carbon composite material with a continuous W fiber grid-reinforced W-Cu coating.

[0015] In one embodiment, the processes of pre-treating the matrix carbon / carbon composite material and the continuous W fiber grid are as follows:

[0016] The matrix carbon / carbon composite material is cut and polished, then ultrasonically cleaned and dried. The continuous W fiber grid is ultrasonically cleaned with deionized water and dried, and a continuous W fiber grid with the same size as the surface of the matrix carbon / carbon composite material is cut.

[0017] The process of preparing the slurry is as follows:

[0018] Polyvinyl alcohol solid particles and deionized water are used to prepare a binder solution with a concentration of 2 - 10 wt.%, and the binder solution and W powder are formulated into a slurry according to a mass ratio of 1:3.

[0019] In one embodiment, the layer spacing between adjacent upper and lower continuous W fiber grids in the carbon / carbon composite material coated with the pre-coating layer is the coating thickness of each layer of W pre-coating layer.

[0020] In one embodiment, the matrix carbon / carbon composite material is a 2.5D carbon / carbon composite material with a density of 1.4 - 1.6 g / cm 3 ; the wire diameter of the continuous W fiber grid is 25 - 50 μm, and the mesh hole is 100 - 156 μm; the powder particle size of the W powder is about 3 - 5 μm.

[0021] In one embodiment, the mass fraction of NaCl powder in the infiltration powder is 1 - 5 wt.%, the mass fraction of KCl powder is 1 - 5 wt.%, the mass fraction of WO3 powder is 45 - 49 wt.%, the mass fraction of Cu powder is 45 - 49 wt.%, and the molar ratio of NaCl powder and KCl powder is 1:1, and the mass ratio of WO3 powder and Cu powder is 1:1.

[0022] In one embodiment, the process of heat treatment is as follows: heating up to 1300 - 1400 °C at a heating rate of 5 °C / min in a vacuum environment, holding for 2 h, and taking it out after natural cooling to room temperature.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention provides a carbon / carbon composite material with a continuous W fiber grid-reinforced W-Cu coating. The coating is composed of a refractory metal W, a sweating metal Cu, and a continuous W fiber grid. Among them, W exists in the form of a particle skeleton and is the main component of the coating, endowing the coating with certain strength and toughness. There are also several layers of continuously stacked W fiber grids inside the coating, which can further strengthen and toughen the coating. In addition, Cu with a low melting point and a high phase change enthalpy distributed in the gaps of the W particle skeleton of the coating can play a role in sweating cooling. The ablation temperature of the carbon / carbon composite material sample with a continuous W fiber grid-reinforced W-Cu coating prepared by the present invention is reduced by about 400 °C compared with that of the carbon / carbon composite material. The flexural strength is increased by 243.25% compared with that of the carbon / carbon composite material and by 35.87% compared with that of the carbon / carbon composite material sample with a W-Cu coating. During the three-point bending test, the fracture mode changes from brittle fracture to plastic fracture, and the ablation damage under the coupled plasma ablation and particle impact environment is significantly reduced compared with that of the W-Cu coating sample. The present invention has low cost, simple operation, and strong designability, providing new technologies and methods for high-strength, high-toughness, and ablation-resistant coatings on the surface of carbon / carbon composite materials.

[0025] The present invention provides a method for preparing a carbon / carbon composite material with a continuous W fiber grid-reinforced W-Cu coating. The slurry brushing method is used to prepare a continuous W f / W porous pre-coating on the surface of the carbon / carbon composite material. The structure of the pre-coating can be controlled by adjusting the number of layers of the continuous W fiber grid and the content of the slurry brushed each time. Combining the reactive infiltration technology to fill the residual pores in the pre-coating, a continuous W fiber grid-reinforced W-Cu coating with a dense structure and good bonding with the matrix can be prepared on the surface of the carbon / carbon composite material. During the infiltration process, the melt passes through the pre-coating and reacts with the carbon / carbon composite material matrix to form a pinning structure. There is a certain composition gradient at the interface between the coating and the matrix, which helps to alleviate the thermal mismatch between the coating and the matrix during the ablation process. The pores in the pre-coating are filled with Cu, and the heat absorption during the phase change of Cu during the ablation process can effectively reduce the material temperature, and the ablation temperature is reduced by about 400 °C compared with that of the carbon / carbon composite material. Description of the Drawings

[0026] Figure 1 SEM photos of the surface of the carbon / carbon composite material sample (a) with a continuous W fiber grid-reinforced W-Cu coating prepared by the present invention and element distribution diagrams (b-c).

[0027] Figure 2 SEM photos of the cross-section of the carbon / carbon composite material sample (a) with a continuous W fiber grid-reinforced W-Cu coating prepared by the present invention: (a) macroscopic morphology; (b) distribution of W fiber network in the W particle skeleton; (c) cross-sectional morphology of W fiber; (d) adjacent upper and lower W fiber grids inside the coating; (e) interface between the coating and the carbon / carbon composite material matrix.

[0028] Figure 3XRD pattern of the surface of the C / C composite sample with a continuous W fiber grid-reinforced W-Cu coating prepared

[0029] Figure 4 Flexural properties of the C / C composite sample with a continuous W fiber grid-reinforced W-Cu coating prepared in the present invention, the C / C composite sample, and the W-Cu coated C / C composite sample: (a) stress-displacement curve; (b) flexural strength and flexural modulus.

[0030] Figure 5 Curve of the surface temperature change with time of the C / C composite sample with a continuous W fiber grid-reinforced W-Cu coating prepared in the present invention and the C / C composite sample during oxyacetylene flame ablation at a heat flux density of 2.4 MW / m 2 for 120 s.

[0031] Figure 6 Ablation performance of the C / C composite sample with a continuous W fiber grid-reinforced W-Cu coating prepared in the present invention and the W-Cu coated C / C composite sample in a plasma ablation coupled particle impact environment: (a) mass and thickness change rates; (b) SEM photograph of the W-Cu coating surface after ablation for 10 s; (c) SEM photograph of the W f / W-Cu coating surface after ablation for 10 s. Detailed implementation manners

[0032] To enable those skilled in the art to understand the features and effects of the present invention, the following provides a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meaning understood by those skilled in the art for the present invention. In case of conflict, the definition in this specification shall prevail.

[0033] The theories or mechanisms described and disclosed herein, whether correct or incorrect, shall not limit the scope of the present invention in any way, that is, the content of the present invention can be implemented without being limited by any specific theory or mechanism.

[0034] In this article, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are only for the sake of brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values (including integers and fractions) within the range.

[0035] In this article, unless otherwise specified, terms such as "comprise", "include", "contain", "have", or similar terms cover the meanings of "consist of" and "consist essentially of". For example, "A comprises a" covers the meanings of "A comprises a and others" and "A only comprises a".

[0036] In this text, for the sake of concise description, not all possible combinations of all technical features in each implementation or embodiment are described. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation or embodiment can be combined arbitrarily, and all possible combinations should be considered as the scope described in this specification.

[0037] The present invention provides a carbon / carbon composite material with a continuous W fiber grid-reinforced W-Cu coating and a preparation method. By using a slurry brushing combined with reactive infiltration technology, the refractory metal W with excellent strength and toughness is used as the skeleton to replace the ultra-high temperature ceramic to prepare the protective coating. The sweating metal Cu is combined to reduce the ablation temperature of the material. A continuous W fiber grid is introduced inside the coating to further improve the strength and toughness of the coating, and a W f / W-Cu coating is constructed on the surface of the carbon / carbon composite material, providing new technologies and methods for the high-strength, high-toughness and ablation-resistant coating on the surface of the carbon / carbon composite material.

[0038] In one aspect, the present invention provides a carbon / carbon composite material with a continuous W fiber grid-reinforced W-Cu coating. The continuous W fiber grid-reinforced W-Cu coating is coated on the surface of the matrix carbon / carbon composite material; the continuous W fiber grid-reinforced W-Cu coating is mainly composed of the refractory metal W with a high melting point and has excellent high-temperature performance; the W inside the continuous W fiber grid-reinforced W-Cu coating exists in the form of a particle skeleton, and the surrounding is filled with the low-melting-point metal Cu with high thermal conductivity and high phase change enthalpy, which can improve the heat conduction and heat dissipation ability of the material and reduce the ablation temperature of the coating; there is a continuous W fiber grid as a reinforcing phase inside the continuous W fiber grid-reinforced W-Cu coating, which can strengthen and toughen the coating; wherein, several layers of continuous W fiber grids are arranged in an upper and lower stacked manner inside the continuous W fiber grid-reinforced W-Cu coating; the continuous W fiber grid-reinforced W-Cu coating is tightly combined with the carbon / carbon composite material matrix without defects such as cracks and pores, and a pinning structure is formed at the interface, with a certain composition gradient, which can relieve the thermal mismatch between the coating and the matrix during the ablation process.

[0039] Among them, the continuous W fiber grid is embedded inside the W-Cu coating and undergoes a certain degree of sintering with the W particle skeleton in the surrounding W-Cu coating.

[0040] The failure mode of the three-point bending test of the above carbon / carbon composite material with a continuous W fiber grid-reinforced W-Cu coating shows plastic fracture.

[0041] In another aspect, the present invention provides a preparation method of a carbon / carbon composite material with a continuous W fiber grid-reinforced W-Cu coating. The steps of the preparation method are as follows:

[0042] Step 1: Cut the matrix carbon / carbon composite material into a certain size and grind it with a sand disk, clean it with deionized water ultrasonically, and then dry it in an electric heating blast drying oven at a temperature of 70°C for 4 to 12 hours;

[0043] The above matrix carbon / carbon composite material has a density of 1.4 to 1.6 g / cm 3 2.5D carbon / carbon composite material.

[0044] Step 2: Pour the polyvinyl alcohol solid particles and deionized water into a beaker and mix them. Place them in a water bath and heat them at 90-95°C and stir them continuously for 0.5-2h to obtain a uniform binder solution with a concentration of 2-10wt.%. The prepared binder solution and W powder are prepared into a slurry in a mass ratio of 1:3. The prepared slurry is fully stirred until there are no obvious agglomerated particles in the slurry.

[0045] Step 3: Use deionized water to ultrasonically clean the continuous W fiber mesh and dry it at 40-50°C, cut the dried continuous W fiber mesh into the same size as the surface of the matrix carbon / carbon composite material cut in step 1, and immerse the cut continuous W fiber mesh in the slurry prepared in step 2. First, use a brush to dip the slurry and then apply a certain thickness of W pre-coating on the surface of the matrix carbon / carbon composite material, and then paste the continuous W fiber mesh impregnated with the slurry on the surface of the carbon / carbon composite material coated with the W pre-coating to form a layer of W f / W pre-coating, after pasting, place the carbon / carbon composite material on a heating plate for drying, after drying, apply the slurry again and paste the continuous W fiber grid impregnated with the slurry, repeat the above steps several times until the W f The W / W pre-coating layer reaches the target thickness and the specified number of continuous W fiber mesh layers to obtain a carbon / carbon composite material coated with a pre-coating layer.

[0046] The wire diameter of the continuous W fiber mesh is about 25-50 μm, the mesh opening is about 100-156 μm, and the powder particle size of the W powder is about 3-5 μm.

[0047] The continuous W fiber grid is dried using an electric hot air drying oven at a temperature of 40-50°C, and the carbon / carbon composite material coated with the pre-coating layer is dried using a heating plate at a temperature of 70-150°C.

[0048] Step 4: Weigh a certain mass of NaCl powder, KCl powder, WO3 powder and Cu powder in proportion and mix them. Pour the mixed powder into a ball mill and ball mill for 8 hours at a ball-to-material ratio of 2:1 to obtain infiltration powder.

[0049] The mass fraction of the NaCl powder is 1-5 wt.%, the mass fraction of the KCl powder is 1-5 wt.%, the mass fraction of the WO3 powder is 45-49 wt.%, the mass fraction of the Cu powder is 45-49 wt.%, and the molar ratio of the NaCl powder to the KCl powder is 1:1, and the mass ratio of the WO3 powder to the Cu powder is 1:1.

[0050] Step 5: Wrap the pre-coated carbon / carbon composite material with the infiltration powder. Specifically, lay 3-5 layers of graphite paper at the bottom and side of the graphite crucible, lay a layer of infiltration powder at the bottom of the crucible with the graphite paper laid, place the pre-coated carbon / carbon composite material on the powder, and spread powder into the graphite crucible until the infiltration powder completely covers the pre-coated carbon / carbon composite material. After the powder addition is completed, first place 3-5 layers of graphite paper above the powder, then place a layer of carbon felt above the graphite paper for sealing treatment, finally cover with a graphite lid, and wrap the graphite crucible with graphite paper.

[0051] Step 6: Place the treated crucible in a heat treatment furnace, heat it up to 1300-1400 °C at a heating rate of 5 °C / min in a vacuum environment, keep it warm for 2 h, turn off the power supply, take it out after natural cooling to room temperature, and obtain a carbon / carbon composite material with a continuous W fiber grid-reinforced W-Cu coating.

[0052] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0053] Conventional instrument equipment in the art is used in the following embodiments. For the experimental methods without specific conditions noted in the following embodiments, they are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer. Various raw materials are used in the following embodiments. Unless otherwise stated, commercially available products are used, and their specifications are conventional specifications in the art. In the specification of the present invention and the following embodiments, unless otherwise specified, "%" all represents weight percentage, "parts" all represents weight parts, and the ratio all represents weight ratio.

[0054] Example 1:

[0055] Step 1: Process a 2.5D carbon / carbon composite material with a density of 1.6 g / cm 3 into a cylindrical sample with a size of φ30 mm × 5 mm, polish it with a diamond sanding disc, ultrasonically clean it with deionized water for 0.5 h, and place it in an electrothermal blast drying oven at 70 °C for drying for 4 h for standby.

[0056] Step 2: Pour 2 wt.% of polyvinyl alcohol solid particles and deionized water into a beaker and mix them. Place the mixture in a water bath at 90 °C and stir continuously for 2 h to obtain a uniform binder solution. Prepare a slurry by mixing the prepared binder solution and tungsten powder at a mass ratio of 1:3. Place the prepared slurry on a magnetic stirrer and stir for 30 min. There are no obvious agglomerated particles in the slurry, and the slurry preparation is completed at this time.

[0057] Step 3: Ultrasonically clean a continuous W fiber grid with a wire diameter of 25 μm and a mesh size of 156 μm, dry it in an electric heating blast drying oven at 40 °C, and then cut it into a circle with a diameter of φ30 mm. Immerse it in the above-prepared slurry. First, use a brush to apply a layer of slurry on the surface of the carbon / carbon composite material, then paste the impregnated continuous W fiber grid on the surface of the carbon / carbon composite material after brushing, and then place it on a heating plate at 70 °C to dry. After drying, apply the slurry again and paste the impregnated continuous W fiber grid. Repeat the above steps until a precoat layer with a thickness of about 1 mm is formed.

[0058] Step 4: Mix 1 wt.% of NaCl powder, 1 wt.% of KCl powder, 49 wt.% of WO3 powder, and 49 wt.% of Cu powder. Pour the mixed powder into a ball milling tank, set the rotation speed at 300 r / min, and ball mill for 8 h at a ball-to-material ratio of 2:1 to obtain infiltration powder. Place the mixed powder in an electric heating blast drying oven at 70 °C and dry for 24 h for standby.

[0059] Step 5: Lay 3 layers of graphite paper at the bottom and side of a graphite crucible. Evenly spread the prepared infiltration powder inside the graphite crucible with a spreading thickness of 5 mm. Place the carbon / carbon composite material coated with the precoat layer above the powder. Pour the infiltration powder to completely cover the carbon / carbon composite material coated with the precoat layer, and then evenly spread the infiltration powder with a thickness of 5 mm. After the powder addition is completed, first place 3 layers of graphite paper above the powder, then place a layer of carbon felt above the graphite paper for sealing treatment, and finally cover it with a graphite lid and wrap the graphite crucible with graphite paper.

[0060] Step 6: Place the treated crucible in a heat treatment furnace. Heat it up to 1300 °C at a heating rate of 5 °C / min in a vacuum environment, keep it warm for 2 h, turn off the power, and take it out after natural cooling to room temperature. Polish the residual melt on the surface of the sample with sandpaper to obtain a carbon / carbon composite material with a W f / W-Cu coating.

[0061] Example 2:

[0062] Step 1: The density is 1.6 g / cm 3The 2.5D carbon / carbon composite material is processed into a cylindrical specimen with dimensions of φ30mm×5mm, polished with a diamond sand disc, ultrasonically cleaned with deionized water for 0.5 h, and dried in an electrothermal blast drying oven at 70 °C for 12 h for standby.

[0063] Step 2: Pour 5 wt.% of polyvinyl alcohol solid particles and deionized water into a beaker and mix them. Place the mixture in a water bath at 95 °C and continuously stir for 0.5 h to obtain a uniform binder solution. Prepare a slurry by mixing the prepared binder solution and tungsten powder at a mass ratio of 1:3. Place the prepared slurry on a magnetic stirrer and stir for 30 min. There are no obvious agglomerated particles in the slurry, and the slurry preparation is completed at this time.

[0064] Step 3: Ultrasonically clean the continuous W fiber mesh with a wire diameter of 50 μm and a mesh size of 100 μm, dry it in an electrothermal blast drying oven at 50 °C, and then cut it into a circle with a diameter of φ30 mm. Immerse it in the above-prepared slurry. First, brush a layer of slurry on the surface of the carbon / carbon composite material with a brush, then paste the impregnated continuous W fiber mesh on the surface of the carbon / carbon composite material coated with the slurry, and then place it on a heating plate at 90 °C for drying. After drying, brush the slurry again and paste the impregnated continuous W fiber mesh. Repeat the above steps until a precoat with a thickness of about 1.3 mm is formed.

[0065] Step 4: Mix 5 wt.% of NaCl powder, 5 wt.% of KCl powder, 45 wt.% of WO3 powder, and 45 wt.% of Cu powder. Pour the mixed powder into a ball milling tank, set the rotation speed at 300 r / min, and ball mill for 8 h at a ball-to-powder ratio of 2:1 to obtain infiltration powder. Place the mixed powder in an electrothermal blast drying oven at 70 °C and dry it for 24 h for standby.

[0066] Step 5: Lay 5 layers of graphite paper at the bottom and side of the graphite crucible. Uniformly spread the prepared infiltration powder inside the graphite crucible with a spreading thickness of 5 mm. Place the carbon / carbon composite material coated with the precoat above the powder. Pour the infiltration powder to completely cover the carbon / carbon composite material coated with the precoat, and then uniformly spread the infiltration powder with a thickness of 5 mm. After the powder addition is completed, first place 5 layers of graphite paper above the powder, then place a layer of carbon felt above the graphite paper for sealing treatment, finally cover the graphite lid, and wrap the graphite crucible with graphite paper.

[0067] Step 6: Place the treated crucible in a heat treatment furnace, heat it to 1400 °C at a heating rate of 5 °C / min in a vacuum environment, hold it for 2 h, turn off the power, take it out after natural cooling to room temperature, and polish the residual melt on the surface of the specimen with sandpaper to obtain a carbon / carbon composite material with a W f / W-Cu coating.

[0068] Example 3:

[0069] Step 1: Process the 2.5D carbon / carbon composite material with a density of 1.4 g / cm 3 into a cylindrical specimen with dimensions of φ30 mm × 10 mm. Polish it with a diamond sanding disc, ultrasonically clean it with deionized water for 0.5 h, and place it in an electrothermal blast drying oven at 70 °C for drying for 12 h for standby.

[0070] Step 2: Pour 8 wt.% of polyvinyl alcohol solid particles and deionized water into a beaker and mix them. Place it in a water bath and heat it at 95 °C while continuously stirring for 0.5 h to obtain a uniform binder solution. Prepare a slurry by mixing the prepared binder solution and tungsten powder at a mass ratio of 1:3. Place the prepared slurry on a magnetic stirrer and stir for 30 min until there are no obvious agglomerated particles in the slurry, and the slurry preparation is completed at this time.

[0071] Step 3: Ultrasonically clean the continuous W fiber grid with a wire diameter of 25 μm and a mesh size of 156 μm, dry it in an electrothermal blast drying oven at 50 °C, and then cut it into a circle with a diameter of φ30 mm. Immerse it in the above-prepared slurry. First, use a brush to apply a layer of slurry on the surface of the carbon / carbon composite material, then paste the impregnated continuous W fiber grid on the surface of the carbon / carbon composite material after coating, and then place it on a heating plate at 150 °C for drying. After drying, apply the slurry again and paste the impregnated continuous W fiber grid. Repeat the above steps until a pre-coating with a thickness of about 2 mm is formed;

[0072] Step 4: Mix 4 wt.% of NaCl powder, 4 wt.% of KCl powder, 46 wt.% of WO3 powder, and 46 wt.% of Cu powder. Pour the mixed powder into a ball milling tank, set the rotation speed at 300 r / min, and ball mill for 8 h at a ball-to-material ratio of 2:1 to obtain infiltration powder. Place the mixed powder in an electrothermal blast drying oven at 70 °C for drying for 24 h for standby.

[0073] Step 5: Lay 5 layers of graphite paper at the bottom and sides of the graphite crucible. Uniformly spread the prepared infiltration powder inside the graphite crucible with a spreading thickness of 5 mm. Place the carbon / carbon composite material coated with the pre-coating above the powder. Pour the infiltration powder to completely cover the carbon / carbon composite material coated with the pre-coating, and then uniformly spread the infiltration powder with a thickness of 5 mm. After the powder addition is completed, first place 5 layers of graphite paper above the powder, then place a layer of carbon felt above the graphite paper for sealing treatment, finally cover it with a graphite lid, and wrap the graphite crucible with graphite paper.

[0074] Step 6: Place the treated crucible in a heat treatment furnace, heat it in a vacuum environment at a heating rate of 5 °C / min to 1400 °C, hold it for 2 h, turn off the power, naturally cool it to room temperature, and then take it out. Polish the residual melt on the surface of the specimen with sandpaper to obtain a carbon / carbon composite material with a W f / W-Cu coating.

[0075] Example 4:

[0076] Step 1: Process a 2.5D carbon / carbon composite material with a density of 1.6 g / cm 3 into a strip-shaped specimen with dimensions of 40 mm × 7 mm × 3 mm. Polish it with a diamond sanding disc, ultrasonically clean it with deionized water for 0.5 h, and place it in an electrothermal blast drying oven at 70 °C for drying for 12 h for standby.

[0077] Step 2: Pour 10 wt.% of polyvinyl alcohol solid particles and deionized water into a beaker and mix them. Place it in a water bath at 95 °C and heat with continuous stirring for 0.5 h to obtain a uniform binder solution. Configure the prepared binder solution and tungsten powder into a slurry according to a mass ratio of 1:3. Place the prepared slurry on a magnetic stirrer and stir for 30 min. There are no obvious agglomerated particles in the slurry, and at this time, the slurry preparation is completed.

[0078] Step 3: Ultrasonically clean a continuous W fiber grid with a wire diameter of 25 μm and a mesh size of 156 μm, dry it in an electrothermal blast drying oven at 50 °C, and then cut it into a strip shape with dimensions of 40 mm × 7 mm × 3 mm. Immerse it in the above-prepared slurry. First, use a brush to apply a layer of slurry on the surface of the carbon / carbon composite material, then paste the impregnated continuous W fiber grid on the surface of the carbon / carbon composite material after coating, and then place it on a heating plate at 120 °C for drying. After drying, apply the slurry again and paste the impregnated continuous W fiber grid. Repeat the above steps until a precoat with a thickness of about 1 mm is formed;

[0079] Step 4: Mix 3 wt.% of NaCl powder, 3 wt.% of KCl powder, 47 wt.% of WO3 powder, and 47 wt.% of Cu powder. Pour the mixed powder into a ball milling tank, set the rotation speed at 300 r / min, and ball mill for 8 h with a ball-to-material ratio of 2:1 to obtain infiltration powder. Place the mixed powder in an electrothermal blast drying oven at 70 °C for drying for 24 h for standby.

[0080] Step 5: Lay 5 layers of graphite paper at the bottom and side of a graphite crucible. Evenly spread the prepared infiltration powder inside the graphite crucible with a powder laying thickness of 5 mm. Place the carbon / carbon composite material coated with the precoat above the powder. Pour the infiltration powder to completely cover the carbon / carbon composite material coated with the precoat, and then evenly spread the infiltration powder with a thickness of 5 mm. After the powder addition is completed, first place 5 layers of graphite paper above the powder, then place a layer of carbon felt above the graphite paper for sealing treatment, finally cover with a graphite lid, and wrap the graphite crucible with graphite paper.

[0081] Step 6: Place the treated crucible in a heat treatment furnace, heat it to 1300 °C at a heating rate of 5 °C / min in a vacuum environment, hold for 2 h, turn off the power, naturally cool to room temperature and then take it out. Polish the residual melt on the surface of the specimen with sandpaper to obtain a specimen with Wf C / C composites with W-Cu coating.

[0082] From Figure 1 the SEM surface photographs and (b) element distribution maps of the C / C composites with continuously W fiber mesh-reinforced W-Cu coating prepared by the present invention, it can be seen that the coating has a dense structure, without obvious defects such as cracks and pores. The continuous W fiber mesh maintains its original mesh structure in the coating, and there is no obvious change in the fiber diameter and mesh holes. The phase distribution around the fibers is uniform, and Cu is distributed in the gaps between W particles.

[0083] Figure 2 SEM cross-section photographs of the C / C composites with continuously W fiber mesh-reinforced W-Cu coating prepared by the present invention. Among them, Figure (a) is the macroscopic morphology; Figure (b) is the distribution of tungsten fiber mesh in the W particle skeleton; Figure (c) is the cross-sectional morphology of tungsten fiber; Figure (d) is the adjacent upper and lower tungsten fiber meshes inside the coating; Figure (e) is the interface between the coating and the matrix. It can be seen from Figure (a) that the coating structure is complete, without obvious defects such as cracks and pores, and the coating thickness is about 1.3 mm. Figure (b) shows the distribution of tungsten fiber mesh inside the W particle skeleton, and the tungsten fiber mesh is embedded inside the W particle skeleton. Figure (c) is the cross-sectional morphology photograph of tungsten fiber. The fiber is dense and sintered to a certain extent with the W particle skeleton in the surrounding W-Cu coating. Appropriate interface bonding helps the load transfer inside the specimen during the loading process. Figure (d) shows the distribution of tungsten fiber mesh layer in the coating. It can be seen that the fiber mesh layer is relatively uniform, and the distance between adjacent upper and lower tungsten fiber mesh layers is about 150 - 170 μm. Figure (e) is the f microscopic morphology photograph of the interface between the W / W-Cu coating and the C / C-W-Cu matrix. The coating and the matrix are well combined, without obvious defects such as cracks and pores. A pinning structure is formed at the interface, and there is a certain composition gradient between the two. The content of W (white phase) inside the coating is relatively high, and the content of Cu (gray phase) inside the matrix is relatively high. The black phase is carbon fiber or carbon matrix.

[0084] Figure 3 XRD pattern of the surface of the prepared C / C composites with continuously W fiber mesh-reinforced W-Cu coating. Only diffraction peaks of W and Cu are detected on the coating surface, indicating that the coating is composed of W and Cu and does not contain other phases; the diffraction peaks are sharp, indicating that W and Cu have good crystallinity.

[0085] Figure 4The flexural properties of the C / C composites, C / C composite specimens, and W-Cu coated C / C composite specimens with continuously W fiber mesh-reinforced W-Cu coatings prepared in this invention are shown. In Figure (a), it is the stress-displacement curve, and in Figure (b), it is the flexural strength and flexural modulus diagram. As can be seen from Figure (a), the load on the specimen increases with the increase of displacement. For the C / C composite specimens and W-Cu coated C / C composite specimens, when the displacement increases to a certain value, the stress reaches the maximum value. Continuing to increase the displacement, the stress rapidly decreases, and the specimen undergoes brittle fracture. For the W f / W-Cu coated specimens, when the displacement increases to a certain value, the rate of increase of stress with the increase of displacement decreases, and the specimen yields. Continuing to increase the displacement, the stress does not change significantly. Continuing to increase the displacement until the stress decreases with the increase of displacement, at this time the specimen fails, indicating that the toughness of the material is significantly improved after introducing the continuously W fiber mesh structure. As can be seen from Figure (b), the flexural strength and flexural modulus of the W f / W-Cu coated specimens are higher than those of the C / C composite specimens and W-Cu coated specimens, indicating that the continuously W fiber mesh structure can strengthen and toughen the coating.

[0086] Figure 5 The curve of the surface temperature change with time during the oxyacetylene flame ablation for 120 s with a heat flux density of 2.4 MW / m 2 of the C / C composites with continuously W fiber mesh-reinforced W-Cu coatings prepared in this invention and the C / C composites. It can be seen that the ablation temperature of the W f / W-Cu coated specimens is about 400 °C lower than that of the C / C composite specimens, indicating that the coating has excellent protective performance.

[0087] Figure 6 The ablation performance of the C / C composite specimens with continuously W fiber mesh-reinforced W-Cu coatings prepared in this invention and the W-Cu coated C / C composite specimens in the plasma ablation coupled particle impact environment, where Figure (a) is the mass and thickness change rate, Figure (b) is the SEM photo of the W-Cu coating surface after ablation for 10 s, and Figure (c) is the SEM photo of the W f / W-Cu coating surface after ablation for 10 s. As can be seen from Figure (a), the mass and thickness change rates of the W f / W-Cu coatings are lower than those of the W-Cu coatings, indicating that the ablation damage of the W f / W-Cu coatings during the ablation process is lower and the protective performance is better. Comparing Figure (b) and Figure (c), it can be seen that the surface of the W-Cu coating is uneven after ablation and is severely eroded by the plasma flame and high-speed particles, while the continuous W fiber mesh in the W f / W-Cu coating can inhibit the erosion of particles on the coating, and the coating surface is relatively flat and dense.

[0088] The above content is only to illustrate the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. The above matrix includes but is not limited to carbon / carbon composites and can be extended and applied to carbon / silicon carbide composites, silicon carbide / silicon carbide composites, graphite materials, etc. The types of coatings include but are not limited to W-Cu coatings and can be extended and applied to metal or ceramic coatings such as W-Ag coatings, Mo-Cu coatings, ZrC coatings, HfC coatings, and SiC coatings. The continuous W fiber grid includes but is not limited to continuous W fiber meshes and can be extended and applied to continuous Mo fiber meshes, continuous C fiber meshes, continuous SiC fiber meshes, etc.

[0089] The present invention discloses a carbon / carbon composite material with a continuous W fiber grid-reinforced W-Cu coating and a preparation method thereof. A pre-coating is prepared on the surface of the carbon / carbon composite material by the slurry brushing method, and the structure of the pre-coating is adjusted by controlling the number of layers of the continuous W fiber grid and the slurry brushing content. The pores in the pre-coating are filled by combining with the reactive infiltration method to obtain a continuously W fiber grid-reinforced W-Cu coating with a dense structure. In the present invention, the refractory metal W is used as the main phase to endow the coating with excellent high-temperature performance, and the low-melting-point metal Cu is filled into the pores to reduce the ablation temperature of the material. The introduction of the continuous W fiber grid structure improves the strength and toughness of the coating. The combination of the slurry brushing method and the reactive infiltration method can not only realize the design and regulation of the coating composition and structure, but also form a pinning structure at the interface between the coating and the matrix and there is a certain composition gradient, alleviating the thermal mismatch between the coating and the matrix and realizing the stable combination of the coating and the matrix. The ablation temperature of the prepared W f / W-Cu coating sample is reduced by about 400 °C compared with the carbon / carbon composite material, the bending strength is increased by 243.25%, the fracture mode is changed from brittle fracture to plastic fracture, and the ablation damage of the plasma ablation coupled with particle impact environment is significantly reduced compared with the W-Cu coating sample.

[0090] The above content is only to illustrate the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims

1. A carbon / carbon composite with a continuous W fiber grid-reinforced W-Cu coating, characterized in that The continuous W fiber grid reinforced W-Cu coating is coated on the surface of the matrix carbon / carbon composite material; the continuous W fiber grid reinforced W-Cu coating is composed of a W-Cu coating and a plurality of layers of continuous W fiber grids arranged in an upper and lower stacked manner inside the W-Cu coating, and the continuous W fiber grids play the role of a reinforcing phase; the W-Cu coating is composed of a W particle skeleton and Cu distributed in the gaps between the W particle skeletons.

2. The carbon / carbon composite material with a continuous W fiber grid-reinforced W-Cu coating according to claim 1, characterized in that The continuous W fiber grid reinforced W-Cu coating is tightly combined with the matrix carbon / carbon composite material, and a pinning structure and a composition gradient exist at the interface between the continuous W fiber grid reinforced W-Cu coating and the matrix carbon / carbon composite material.

3. The carbon / carbon composite material with a continuous W fiber grid-reinforced W-Cu coating according to claim 1, characterized in that, The continuous W fiber grid is embedded inside the W-Cu coating and sintered with the W particle skeleton in the surrounding W-Cu coating.

4. The carbon / carbon composite material with a continuous W fiber grid-reinforced W-Cu coating according to claim 1, characterized in that The failure mode of the three-point bending test of the carbon / carbon composite material with the continuous W fiber grid reinforced W-Cu coating shows plastic fracture.

5. A method for preparing a carbon / carbon composite with a continuous W fiber grid-reinforced W-Cu coating as described in any one of claims 1 to 4, characterized in that, It includes the following steps: Pre-treat the matrix carbon / carbon composite material and the continuous W fiber grid respectively; Prepare a slurry; Immerse the continuous W fiber grid in the slurry. At the same time, dip a brush into the slurry and apply a W pre-coating on the surface of the matrix carbon / carbon composite material. After applying a W pre-coating with a certain thickness, paste the continuous W fiber grid impregnated with the slurry on the surface of the matrix carbon / carbon composite material coated with the W pre-coating to form a layer of W f / W pre-coating; dry the W f / W pre-coating, then apply the slurry again, paste the continuous W fiber grid impregnated with the slurry, and dry it. Repeat the above steps several times until the W f / W pre-coating reaches the target thickness and the specified number of layers of continuous W fiber grids, and the carbon / carbon composite material coated with the pre-coating is prepared; Mix NaCl powder, KCl powder, WO3 powder and Cu powder to obtain an infiltration powder; Coat the carbon / carbon composite material coated with a pre-coating with the infiltration powder, and then perform heat treatment to obtain a carbon / carbon composite material with a continuous W fiber grid reinforced W-Cu coating.

6. The carbon / carbon composite material with a continuous W fiber grid-reinforced W-Cu coating according to claim 5, characterized in that, The process of pre-treating the matrix carbon / carbon composite material and the continuous W fiber grid respectively is as follows: Cut and polish the matrix carbon / carbon composite material, then perform ultrasonic cleaning and drying, use deionized water to perform ultrasonic cleaning on the continuous W fiber grid and dry it, and cut the continuous W fiber grid with the same size as the surface of the matrix carbon / carbon composite material; The process of preparing the slurry is as follows: Prepare a binder solution with a concentration of 2-10 wt.% using polyvinyl alcohol solid particles and deionized water, and prepare a slurry by mixing the binder solution and W powder at a mass ratio of 1:

3.

7. The carbon / carbon composite material with a continuous W fiber grid-reinforced W-Cu coating according to claim 5, characterized in that, The layer spacing between adjacent continuous W fiber grids in the carbon / carbon composite material coated with a pre-coating is the coating thickness of each layer of W pre-coating.

8. The preparation method of the carbon / carbon composite material with a continuous W fiber grid-reinforced W-Cu coating according to claim 5, characterized in that, The matrix carbon / carbon composite material is a 2.5D carbon / carbon composite material with a density of 1.4 to 1.6 g / cm 3 ; the wire diameter of the continuous W fiber grid is 25 to 50 μm, and the mesh hole is 100 to 156 μm.

9. The preparation method of the carbon / carbon composite material with a continuous W fiber grid-reinforced W-Cu coating according to claim 5, characterized in that, In the infiltration powder, the mass fraction of NaCl powder is 1-5 wt.%, the mass fraction of KCl powder is 1-5 wt.%, the mass fraction of WO3 powder is 45-49 wt.%, the mass fraction of Cu powder is 45-49 wt.%, and the molar ratio of NaCl powder and KCl powder is 1:1, and the mass ratio of WO3 powder and Cu powder is 1:

1.

10. The preparation method of the carbon / carbon composite material with a continuous W fiber grid-reinforced W-Cu coating according to claim 5, characterized in that, The process of the heat treatment is as follows: Heat up to 1300-1400 °C at a heating rate of 5 °C / min in a vacuum environment, keep it warm for 2 h, and take it out after natural cooling to room temperature.

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