RMI buffer layer and ceramic matrix composite reaction infiltration method

Abstract

The present application relates to a kind of ceramic matrix composite reaction infiltration methods, including pretreatment, buffer layer covering component, molten silicon infiltration, the process of clearing material, buffer layer is fixed on the surface of component preform, prepare ceramic matrix composite.The present application also relates to a kind of RMI buffer layer, including single-sided oily paper, solid glue, C powder, laminated structure, in turn single-sided oily paper, solid glue, C powder, solid glue, single-sided oily paper.Single-sided oily paper can also be replaced by double-sided oily paper or graphite paper or paper, solid glue can also be replaced by the mixture of glue powder and water.The reaction infiltration method of the present application covers buffer layer on the surface of preform, prevents molten state Si powder from directly contacting component surface, solves the problem of sticking material, improves the quality of component.The RMI buffer layer of the present application can block molten state liquid silicon from eroding carbon fiber, prevent fiber from being damaged, play the role of protecting fiber, ensure that the size of component is not affected.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ceramic matrix composite material preparation, and particularly relates to an RMI buffer layer and a ceramic matrix composite material reaction melt infiltration method. BACKGROUND

[0002] Carbon fiber toughened silicon carbide (C / SiC) ceramic matrix composite material and carbon fiber reinforced carbon-silicon carbide double matrix ceramic matrix composite material (C / C-SiC) have a series of excellent performances such as high specific strength, high specific modulus, ablation resistance, high temperature resistance and low density, which combine the advantages of carbon / carbon (C / C) composite material and SiC ceramic. At present, the preparation methods thereof mainly include chemical vapor infiltration (CVI), polymer impregnation pyrolysis (PIP), gas phase silicon infiltration (GSI) or reaction melt infiltration (RMI) method. The RMI process has a short preparation cycle, a simple process and low cost. On the other hand, the composite material obtained by the RMI process has high density, low porosity and excellent heat conduction performance, and can realize the preparation of complex shape components and near net shape forming. Therefore, the RMI process is widely applied to the preparation of various ceramic matrix composite materials in the fields of aerospace thermal structure, light thermal protection and brake.

[0003] The principle of RMI is that molten metal silicon (Si) reacts with solid carbon (C) source prepared by the CVI / CVD / PIP process under vacuum and high temperature conditions to generate SiC matrix. The reaction is exothermic, fast and highly active. As the last process of the component ceramicization process, the RMI has the characteristics of near net shape forming, and the size of the component after RMI is close to the final size. However, if the carbon source covered by the carbon fiber on the surface of the component is insufficient or part of the carbon fiber is exposed after processing, the surface carbon fiber may react with the infiltrated molten metal in the RMI process, so that the carbon fiber is eroded and the surface fiber is detached, which affects the quality and final size of the component. SUMMARY

[0004] In order to overcome the problem that the molten Si in the RMI process easily erodes the surface carbon fiber and affects the quality and size of the component, the application provides an RMI buffer layer and a ceramic matrix composite material reaction melt infiltration method.

[0005] The technical solution adopted by the application to solve the technical problem is:

[0006] A ceramic matrix composite material reaction melt infiltration method, comprising the following steps:

[0007] Step 1, pretreatment

[0008] Preparation of boron nitride slurry, the boron nitride slurry is used as a brushing material, and the crucible for reaction melt infiltration is brushed.

[0009] Step 3, buffer layer covering component

[0010] The buffer layer is fixed on the surface of the component preform. The buffer layer is fixed on the surface of the component preform by double-sided adhesive tape.

[0011] Step 4, silicon melt infiltration

[0012] The component preform with the fixed buffer layer is placed in a crucible filled with silicon powder, and the component preform is surrounded by the silicon powder. The component preform is heated at a set temperature to perform silicon melt infiltration.

[0013] Step 5, material cleaning

[0014] After the completion of the silicon melt infiltration of the component preform, the buffer layer covering the component and the residual material of the silicon melt infiltration are cleaned. A silicon carbide ceramic matrix composite component with a required density is obtained.

[0015] The ceramic matrix composite reaction melt infiltration method described above, wherein the step 1, pretreatment, further comprises:

[0016] Preparation of boron nitride slurry: uniformly mix boron nitride and anhydrous ethanol at a mass ratio of 1:1-3, evaporate part of the anhydrous ethanol at 50-70°C, until the mixture becomes paste-like, to obtain boron nitride slurry.

[0017] The ceramic matrix composite reaction melt infiltration method described above, wherein the thickness of the double-sided adhesive tape for fixing the buffer layer is 0.05 mm.

[0018] The ceramic matrix composite reaction melt infiltration method described above, wherein the step 4, silicon melt infiltration, further comprises:

[0019] The silicon melt infiltration is performed in a vacuum environment with a vacuum degree ≤200 Pa, and the heating rate and holding time are as follows: from room temperature to 1250°C at a rate of 4-5°C / min, holding for 1 h; from 1250°C to 1350°C at a rate of 1-2°C / min, holding for 1 h; from 1350°C to 1450°C at a rate of 1-2°C / min, holding for 1 h; from 1450°C to 1530°C at a rate of 1-2°C / min, holding for 1-3 h, and then cooling to room temperature with the furnace.

[0020] The ceramic matrix composite reaction melt infiltration method described above, wherein after the completion of the material cleaning, the density of the prepared silicon carbide ceramic matrix composite component is 1.92 g / cm 3 .

[0021] The ceramic matrix composite reaction melt infiltration method described above, wherein in the step 4, silicon melt infiltration, the component preform can also be surrounded by a mixed powder of silicon powder and silicon carbide powder, and the mass ratio of the silicon powder to the silicon carbide powder in the mixed powder is 1-5:1.

[0022] An RMI buffer layer, comprising single-sided oily paper, solid glue, and C powder.

[0023] The buffer layer is a laminated structure, sequentially comprising single-side oily paper, solid glue, C powder, solid glue, and single-side oily paper, and the oily surface of the single-side oily paper is coated with solid glue.

[0024] The RMI buffer layer described above has a single-side oily paper with a thickness of 0.15 mm, a C powder with a thickness of 0.5 mm and a mesh number of 100-300, and a single-layer double-sided adhesive with a thickness of 0.05 mm.

[0025] The RMI buffer layer described above has a single-side oily paper that can be replaced by double-side oily paper or graphite paper or paper, and solid glue coated on any one side thereof.

[0026] The RMI buffer layer described above has solid glue that can be double-sided adhesive, or a mixture of polyvinyl alcohol (PVA) glue powder and water, with a weight ratio of 1:40-60.

[0027] The present application has the following advantages:

[0028] A ceramic matrix composite reaction infiltration method, according to the reaction mechanism of RMI, a certain thickness of buffer layer is covered on the surface of the component preform, and the component is infiltrated through the buffer layer. It can prevent the Si powder in the molten state from directly contacting the surface of the component, solve the problem of sticking material, reduce the occurrence of fiber shedding phenomenon on the surface, and improve the quality of the component.

[0029] A ceramic matrix composite reaction infiltration method, the paper in the buffer layer is carbonized at high temperature during the infiltration process, and the glue is decomposed at high temperature during the infiltration process, without affecting the quality of the component.

[0030] An RMI buffer layer, the buffer layer can block the molten liquid silicon from eroding the carbon fiber, prevent the fiber from being damaged, play a protective role for the fiber, and ensure that the size of the component is not affected. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a schematic diagram of the positions of the crucible, powder, buffer layer, and component when the present application is applied;

[0032] Figure 2 is Figure 1 is an enlarged view of position A in FIG.

[0033] Figure 3 is an RMI temperature rise curve when the present application is applied;

[0034] Figure 4 is a CT image of a component prepared by the present application;

[0035] Figure 5 is a surface of a component prepared without using a buffer layer;

[0036] Figure 6 The component surface is prepared using a buffer layer.

[0037] In the figure: 1. Crucible, 2. Filling powder, 3. Component, 4. C powder, 5. Oily paper. DETAILED DESCRIPTION

[0038] Example 1

[0039] A ceramic matrix composite reaction infiltration method based on RMI buffer layer, comprising the following steps:

[0040] Step one: Preparation

[0041] 1) Preparation of component blank before RMI;

[0042] 2) Preparation of component RMI special crucible;

[0043] 3) Crucible brushing paint

[0044] Mix boron nitride and anhydrous ethanol uniformly according to a mass ratio of 1:1-3, evaporate part of the anhydrous ethanol at 50-70℃ until the mixture is paste-like, obtain boron nitride slurry as brushing paint, which can prevent the molten powder from sticking to the crucible after cooling;

[0045] 4) Mixing powder

[0046] Mix silicon powder and silicon carbide powder uniformly according to a mass ratio of 1-5:1 using a gravity-free mixer, obtain mixed powder.

[0047] Step two: Making buffer layer

[0048] 1) Prepare oily paper with a thickness of 0.1-0.3mm (any organic matter that can be converted into carbon element-containing organic matter under vacuum inert atmosphere, such as paper, graphite paper, etc.).

[0049] 2) Cut the oily paper prepared in 1) into 4 pieces of the same shape that fit the component. The thickness of the oily paper covering the upper / in and lower / out surfaces of the component is equal, i.e. 上 = h 下 ;

[0050] 3) Use glue to uniformly brush one surface of 2) cut oily paper, and the glue covers the surface during brushing, which does not need to be repeated; the glue is a mixture of polyvinyl alcohol (PVA), hydroxypropyl methylcellulose (HPMC) and water, solid glue, double-sided adhesive tape, etc., and the ratio of glue powder to water is 1:40-60;

[0051] 4) evenly stick C powder on the surface of the one piece of the oil paper in 3), the thickness of the C powder is 1-3:1 of the total thickness of the oil paper, the total thickness of the oil paper is h=h 上 +h 下 , the mesh of the C powder is 100-300 mesh;

[0052] 5) cover the other piece of the oil paper in 3) on the oil paper in 4) to make a buffer layer covering one surface of the covering member.

[0053] 6) repeat 3), 4) and 5) to make a buffer layer covering the other surface of the covering member.

[0054] Step three: use the buffer layer covering member

[0055] 1) stick double-sided adhesive tape on the surface of the member, the thickness of the double-sided adhesive tape is 0.05mm, for fixing;

[0056] 2) cover the buffer layer material prepared in step two on the surface of the member;

[0057] Step four: melt and infiltrate silicon

[0058] put the member covered with the buffer layer material and filled with the mixed powder around the member into a crucible and send it into a vacuum furnace, and perform RMI according to the temperature curve, which specifically includes: Figure 4

[0059] 4.1) put the member covered with the buffer layer material and filled with the mixed powder around the member on the bottom plate of the vacuum furnace, and send it into the furnace chamber by using the lifting platform;

[0060] 4.2) start the vacuum pump to vacuumize the furnace chamber, when the vacuum degree is less than or equal to 200Pa, start the power supply, start heating, and increase the temperature from room temperature to 1250±20℃ at a rate of 4-5℃ / min, keep the temperature at 1250℃ for 1h, then increase the temperature from 1250℃ to 1350℃ at a rate of 1-2℃ / min, keep the temperature at 1350℃ for 1h, then increase the temperature from 1350℃ to 1450℃ at a rate of 1-2℃ / min, keep the temperature at 1450℃ for 1h, then increase the temperature from 1450℃ to 1530℃ at a rate of 1-2℃ / min, keep the temperature at 1530℃ for 1-3h, and then decrease the temperature to room temperature;

[0061] Step five: clean the material

[0062] after the reaction is completed, when the temperature decreases to room temperature, open the furnace to take out the crucible, and clean all the buffer layer material covering the member and the residual material after the reaction, to obtain the member with a density greater than 1.9g / cm 3 .

[0063] Example 2

[0064] The RMI process of the member mainly includes:​

[0065] Step one: Preparation

[0066] 1) Preparation of component blank before RMI;

[0067] 2) Preparation of component RMI special crucible;

[0068] 3) Crucible brush paint

[0069] Mix boron nitride and anhydrous ethanol uniformly according to the mass ratio of 1:1, evaporate part of anhydrous ethanol at 50-70℃ until the mixture is paste, get boron nitride slurry as brush paint, which can prevent the molten powder from sticking to the crucible after cooling;

[0070] 4) Mix the powder

[0071] Mix silicon powder and silicon carbide powder uniformly according to the mass ratio of 2:1 using gravity-free mixer, get mixed powder.

[0072] Step two: making buffer layer

[0073] 1) Prepare single-sided oily paper with a thickness of 0.15mm;

[0074] 2) Cut the single-sided oily paper prepared in 1) into a shape that fits the component;

[0075] 3) Use solid glue to evenly brush the non-oily side of the two pieces of single-sided oily paper cut in 2);

[0076] 4) Cover the surface of one piece of oily paper in 3) with C powder, the thickness of C powder is 0.5mm, and the mesh number of C powder is 100;

[0077] 5) Cover the oily side of the other piece of oily paper in 3) with C powder, the thickness of C powder is 0.5mm, and the mesh number of C powder is 100;

[0078] 6) Repeat 3), 4), and 5) to make a buffer layer covering the other surface of the component.

[0079] Step three: use buffer layer to cover component

[0080] 1) Paste double-sided adhesive tape on the upper and lower surfaces of the component, the thickness of the double-sided adhesive tape is 0.05mm, which is used for fixing;

[0081] 2) Paste the buffer layer material prepared in step two on the upper and lower surfaces of the component respectively;

[0082] Step four: melt and infiltrate silicon

[0083] Place the component covered with buffer layer material and filled with mixed powder around the component into the crucible and send it into the vacuum furnace according to Figure 4RMI was performed on the temperature profile;

[0084] Step 5: Cleaning

[0085] After the reaction was complete and the temperature had cooled to room temperature, the furnace was opened, the crucible was removed, and all buffer layer material covering the components and any remaining material after the reaction were cleaned off, yielding a product with a density greater than 1.9 g / cm³. 3 Components.

[0086] In this embodiment, the density of the component after RMI is 1.92 g / cm³. 3 The density and size meet the requirements, from Figure 4 The CT scan shows that the component has uniform density after RMI. Figure 6 It can be seen that there was no material adhesion or fiber shedding on the surface of the component after RMI.

Claims

1. A ceramic matrix composite reaction infiltration process, characterized by, It comprises the following steps: Step 1, pretreatment: Preparation of boron nitride slurry, boron nitride slurry as the coating material, coating the reaction infiltration crucible; Step 2, making buffer layer The buffer layer comprises single-sided oily paper, solid glue, and C powder; The buffer layer has a laminated structure, which comprises single-sided oily paper, solid glue, C powder, solid glue, and single-sided oily paper in sequence, and the oily surface of the single-sided oily paper is coated with solid glue; The C powder has a mesh size of 100-300; Step 3, buffer layer covering component: Fix the buffer layer on the surface of the component preform; and use double-sided adhesive to fix the buffer layer on the surface of the component preform; Step 4, silicon melting and infiltration: Place the component preform with the fixed buffer layer into a crucible filled with silicon powder, and fill the silicon powder around the component preform; heat at a set temperature to perform silicon melting and infiltration of the component preform; Step 5, cleaning: After the completion of silicon melting and infiltration of the component preform, clean the buffer layer and residual material covering the component; and obtain a silicon carbide ceramic matrix composite component with a required density.

2. The ceramic matrix composite reaction infiltration method of claim 1, wherein, The step 1, pretreatment, further comprises: Preparation of boron nitride slurry: uniformly mix boron nitride and anhydrous ethanol at a mass ratio of 1:1-3, evaporate part of the anhydrous ethanol at 50-70℃, until the mixture becomes paste, and obtain the boron nitride slurry.

3. The ceramic matrix composite reaction infiltration method of claim 2, wherein, The double-sided adhesive used for fixing the buffer layer has a thickness of 0.05 mm.

4. The ceramic matrix composite reaction infiltration method of claim 3, wherein, The step 4, silicon melting and infiltration, further comprises: The silicon melting and infiltration is performed in a vacuum environment with a vacuum degree of ≤200 Pa, and the heating rate and holding time are as follows: increase the temperature from room temperature to 1250℃ at a rate of 4-5℃ / min, hold for 1 h; then increase the temperature from 1250℃ to 1350℃ at a rate of 1-2℃ / min, hold for 1 h; then increase the temperature from 1350℃ to 1450℃ at a rate of 1-2℃ / min, hold for 1 h; then increase the temperature from 1450℃ to 1530℃ at a rate of 1-2℃ / min, hold for 1-3 h, and then cool to room temperature with the furnace.

5. The ceramic matrix composite reaction infiltration method of claim 4, wherein, The cleaning is completed, and the density of the prepared silicon carbide ceramic matrix composite member is 1.92 g / cm 3 .

6. The ceramic matrix composite reaction infiltration method of claim 4, wherein, In the step 4, silicon melting and infiltration, the silicon powder around the component preform is replaced with a mixed powder of silicon powder and silicon carbide powder, and the mass ratio of the silicon powder to the silicon carbide powder in the mixed powder is 1-5:

1.

7. The ceramic matrix composite reaction infiltration process of claim 1, wherein, The single-sided oily paper has a thickness of 0.15 mm, the C powder has a thickness of 0.5 mm, and the single-layer double-sided adhesive has a thickness of 0.05 mm.

8. The ceramic matrix composite reaction infiltration process of claim 1, wherein, The single-sided oily paper is replaced by double-sided oily paper or graphite paper, and solid glue is coated on any one side of the single-sided oily paper.

9. The ceramic matrix composite reaction infiltration process of claim 1, wherein, The solid glue is replaced by double-sided adhesive, or a mixture of polyvinyl alcohol (PVA) and hydroxypropyl methylcellulose (HPMC) glue powder and water, wherein the weight ratio of the glue powder to water is 1:40-60.

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