Preparation method of SiC / SiC composite material and composite material thereof

Abstract

The invention relates to a preparation method of a SiC / SiC composite material. The preparation method comprises the following steps: S1, forming a single-layer or multi-layer interface on SiC fibers; s2, providing dipping slurry containing rare earth silicate, immersing the fibers with the formed interface in the dipping slurry for vacuum dipping, heating and curing to fix the slurry, and heating and cracking to remove organic matters and form a porous structure at the same time to obtain a SiC / SiC composite material with a porous matrix; and S3, SiC is generated through a polymer precursor infiltration pyrolysis method, and matrix densification treatment is carried out. The invention further relates to the composite material which is obtained through the preparation method. According to the preparation method of the SiC / SiC composite material, the composite material matrix is modified only through a simple slurry impregnation process, the process is simple, the cost is low, the oxidation resistance of the material can be improved, and meanwhile, the negative influence of reaction thermal stress on the material is reduced.

Description

Technical Field

[0001] The present invention relates to a composite material, and more particularly to a preparation method of a SiC / SiC composite material and the composite material. Background Art

[0002] SiC / SiC composites are high-performance materials with complex structures composed of fibers, interfaces, and matrices. They can be used as hot-end components of aero-engines in the aerospace field because of their excellent mechanical properties, light weight, and high temperature resistance. However, the working environment of aero-engines is extremely harsh, and they are faced with coupling effects such as high temperature loads, cyclic stresses, gas scouring, and corrosive environments, which cause premature failure of materials. Among them, high-temperature oxidation erosion has a serious impact on material properties. The SiC matrix is ​​oxidized into gas phase components such as Si(OH)4 in a high-temperature water-oxygen coupling environment, which form pores after volatilization, destroying the protective effect of the dense matrix on the interface and fibers of the composite material, causing serious degradation of the mechanical properties of the material, premature failure of components, and other hazards. Therefore, improving the high-temperature oxidation resistance of SiC / SiC composites, especially the oxidation resistance of the matrix, is an important way to reduce the risk of material failure.

[0003] At present, there are few studies on improving the oxidation resistance of modified SiC matrix materials. Usually, the method of introducing a second phase material with oxidation resistance or self-healing ability by in-situ reaction is used for improvement. CN202211419352 discloses a method for preparing a SiC / SiC-SiBYYb composite material, which generates a quaternary matrix with YbB4, YB4, Si and YSi2 phases in situ inside a porous SiC / SiC composite embryo by impregnating YbB6 powder with slurry and reacting to infiltrate Si-Y alloy, and consumes corrosive gases through an oxidation process and generates an anti-water and oxygen phase in situ, thereby improving the composite material's resistance to water and oxygen corrosion and self-healing properties. However, the in-situ preparation process involves complex reactions, and there are unevenly distributed thermal stresses, which can easily cause microcracks inside the material, which is not conducive to application in a service environment, and the preparation process is complicated and costly. Summary of the invention

[0004] In order to solve the problems of complicated process of introducing multi-phase materials by in-situ reaction in the above-mentioned prior art, the present invention provides a method for preparing a SiC / SiC composite material and the composite material thereof.

[0005] According to the preparation method of the SiC / SiC composite material of the present invention, it comprises the following steps: S1, forming a single-layer or multi-layer interface on SiC fiber; S2, providing an impregnation slurry comprising rare earth silicate, immersing the fiber after the interface is formed in the impregnation slurry for vacuum impregnation, heating and curing to fix the slurry, heating and cracking to remove organic matter and simultaneously forming a porous structure to obtain a SiC / SiC composite material with a porous matrix; and S3, generating SiC by a polymer precursor impregnation and cracking method to perform matrix densification treatment.

[0006] In a preferred embodiment, the interface is a BN interface, a PyC interface, or a BN / SiC multilayer interface.

[0007] In a preferred embodiment, the thickness of the interface is 50-2000 nm.

[0008] In a preferred embodiment, in step S1, the interface is formed by chemical vapor deposition (CVD). In a preferred embodiment, SiC fiber is placed in a reaction furnace, ammonia (NH3) and boron trichloride (BCl3) are used as reaction gases, hydrogen (H2) is used as diluent gas, the deposition pressure is 0.1~10 KPa, the deposition temperature is 700~1100℃, the deposition time is 10~300 min, and the gas flow ratio is BCl3: NH3 = 1: (0.5~5), BCl3: H2 = 1: (1~20).

[0009] In a preferred embodiment, the rare earth silicate is one or more of Yb2Si2O7, Y2Si2O7, Ho2Si2O7, Yb2SiO5, Y2SiO5, or Ho2SiO5.

[0010] In a preferred embodiment, in step S2, SiC powder and rare earth silicate powder are mixed in a mass ratio of 1: (0.05-10) to obtain a mixed powder, and the mixed powder is ball-milled in a mass ratio of mixed powder: solvent: dispersant: binder: curing agent = 1: (0.5-3): (0.02-0.3): (0.02-0.2): (0.02-0.2) to obtain an impregnation slurry.

[0011] In a preferred embodiment, the impregnation slurry is obtained by ball milling in a polytetrafluoroethylene ball mill for 12 to 120 hours, and the ball milling medium is SiC balls.

[0012] In a preferred embodiment, in step S2, vacuum impregnation is performed in a vacuum impregnation tank for 0.5-5 h, curing is performed in a high temperature oven at 80-120° C. for 10-30 h, and pyrolysis is performed in a vacuum carbon tube furnace at 700-1100° C. for 0.5-3 h.

[0013] In a preferred embodiment, the precursor is polycarbosilane (PCS) or polydimethylsilane (PDMS).

[0014] In a preferred embodiment, in step S3, the SiC / SiC composite material is vacuum impregnated with a precursor, and the precursor is cracked under an inert gas to obtain SiC to increase density.

[0015] In a preferred embodiment, the pyrolysis conditions of the precursor are 800-1200° C. for 0.5-5 h.

[0016] In a preferred embodiment, step S3 is repeated 5 to 20 times.

[0017] The composite material according to the present invention is obtained by the above-mentioned method for preparing the SiC / SiC composite material.

[0018] According to the preparation method of the SiC / SiC composite material of the present invention, the composite material matrix is ​​modified only by a simple slurry impregnation process, that is, the antioxidant component is directly introduced into the material through the slurry impregnation process, the process is simple, the cost is low, and the material's antioxidant property can be improved, that is, the material's antioxidant erosion ability is improved, while reducing the negative impact of reaction thermal stress on the material. Specifically, the rare earth silicate introduced in this way has a thermal expansion coefficient similar to that of the SiC matrix, and the thermal stress is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The figure is a simplified process flow chart of the method for preparing the SiC / SiC composite material according to the present invention.

[0020] Figure 2 This is a cross-sectional morphology diagram of the SiC / SiC-Yb2Si2O7 composite material according to Example 1 of the present invention.

[0021] Figure 3 This is a fracture morphology of the SiC / SiC-Yb2Si2O7 composite material according to Example 1 of the present invention after being oxidized by water and oxygen at 1200°C for 80 hours.

[0022] Figure 4 This is a cross-sectional morphology diagram of the SiC / SiC-Yb2Si2O7 composite material according to Example 2 of the present invention.

[0023] Figure 5 3 is a fracture morphology diagram of the SiC / SiC composite material according to Comparative Example 1 of the present invention after being oxidized by water and oxygen at 1200° C. for 80 h. DETAILED DESCRIPTION

[0024] The preferred embodiments of the present invention are given below in conjunction with the accompanying drawings and described in detail.

[0025] like Figure 1 As shown, the preparation method of the SiC / SiC composite material according to the present invention first includes forming a single layer or a multilayer interface on the SiC fiber. In a preferred embodiment, the interface is a BN interface, a PyC interface, or a BN / SiC multilayer interface. In a preferred embodiment, the interface is formed by chemical vapor deposition (CVD). In a preferred embodiment, the thickness of the interface is 50~2000 nm. Specifically, the SiC fiber is placed in a reaction furnace, ammonia (NH3) and boron trichloride (BCl3) are used as reaction gases, and hydrogen (H2) is used as diluent gas. A layer of BN interface with a thickness of 50~2000 nm is deposited by chemical vapor deposition (CVD), the deposition pressure is 0.1~10 KPa, the deposition temperature is 700~1100℃, the deposition time is 10~300 min, and the gas flow ratio is BCl3: NH3 = 1: (0.5~5), BCl3: H2 = 1: (1~20).

[0026] The preparation method of the SiC / SiC composite material according to the present invention then includes providing an impregnation slurry including rare earth silicate and treating the fiber after forming the interface with the impregnation slurry. In a preferred embodiment, the rare earth silicate is one or more of Yb2Si2O7, Y2Si2O7, Ho2Si2O7, Yb2SiO5, Y2SiO5, or Ho2SiO5. It should be understood that by adjusting the proportion of rare earth silicate in the impregnation slurry, the amount of the second phase material (i.e., rare earth silicate) introduced into the SiC / SiC composite material can be controlled, thereby controlling the anti-oxidation effect of the SiC / SiC composite material.

[0027] Specifically, SiC powder (particle size of 300-1000 nm) and Yb2Si2O7 powder (300-1000 nm) are mixed in a mass ratio of 1:(0.05-10) to obtain a mixed powder, and the mixed powder: solvent (e.g., anhydrous ethanol): dispersant (e.g., fish oil): binder (e.g., polyvinyl butyral PVB): curing agent (e.g., phenolic resin) = 1:(0.5-3):(0.02-0.3):(0.02-0.2):(0.02-0.2) are added into a polytetrafluoroethylene ball mill, and the impregnation slurry is obtained by ball milling for 12-120 h, and the ball milling medium is SiC balls.

[0028] Specifically, the fiber after forming the interface is immersed in the impregnation slurry, and vacuum impregnation is performed in a vacuum impregnation tank for 0.5 to 5 hours. Subsequently, it is cured in a high-temperature oven for 10 to 30 hours at a curing temperature of 80 to 120 °C. Finally, it is pyrolyzed in a vacuum carbon tube furnace to remove organic matter and form a porous structure to obtain a SiC / SiC composite material with a porous matrix. The pyrolysis atmosphere is an inert atmosphere, the pyrolysis temperature is 700 to 1100 °C, and the pyrolysis time is 0.5 to 3 hours.

[0029] The preparation method of the SiC / SiC composite material according to the present invention finally includes generating SiC by a polymer precursor impregnation pyrolysis method for matrix densification treatment. In a preferred embodiment, the precursor is polycarbosilane (PCS) or polydimethylsilane (PDMS). Specifically, the SiC / SiC composite material is vacuum impregnated with a precursor and pyrolyzed under an inert atmosphere at 800-1200 °C for 0.5-5 h. In order to increase the density of the material, the impregnation pyrolysis process is repeated 5-20 times to obtain a SiC / SiC-Yb2Si2O7 composite material.

[0030] Example 1 The SiC fiber was placed in a reactor, and a 300 nm thick BN interface was deposited by chemical vapor deposition (CVD) using ammonia (NH3) and boron trichloride (BCl3) as reaction gases and hydrogen (H2) as diluent gas. The deposition pressure was 2 KPa, the deposition temperature was 900 ℃, the deposition time was 180 min, the B source was BCl3, the gas flow rate was 20 mL / min, the N source was NH3, the gas flow rate was 60 mL / min, and the H2 gas flow rate was 180 mL / min.

[0031] 10 g SiC powder (300 nm particle size), 20 g Yb2Si2O7 powder (300 nm particle size), 45 g anhydrous ethanol, 3 g fish oil, 1.5 g polyvinyl butyral and 1.5 g phenolic resin were mixed and ball milled for 24 h to obtain the impregnation slurry.

[0032] The fiber after the deposition interface was immersed in the slurry and vacuum impregnated in a vacuum impregnation tank for 1 h. The impregnated fiber and the slurry were placed in a 100 °C oven for curing for 12 h. Subsequently, the fiber was pyrolyzed in a 1100 °C vacuum carbon tube furnace for 1 h to obtain a SiC / SiC composite material with a porous matrix.

[0033] Polycarbosilane (PCS) was used as a precursor to impregnate the porous matrix of SiC / SiC composites with polycarbosilane, and then vacuum impregnation was performed in a vacuum impregnation tank for 1 h. Then, PCS was pyrolyzed at 1100 °C for 2 h in an Ar atmosphere to generate SiC. The PCS impregnation and pyrolysis process was repeated 8 times to obtain SiC / SiC-Yb2Si2O7 composites.

[0034] The SiC / SiC-Yb2Si2O7 composite material prepared in this example has a dense structure, a flexural strength of 470 MPa, and a strength retention rate of 85.8% after water-oxygen oxidation at 1200°C for 80 h.

[0035] Figure 2 This is a cross-sectional morphology of the SiC / SiC-Yb2Si2O7 composite material prepared in this example. As can be seen from the figure, the SiC / SiC-Yb2Si2O7 composite material exhibits a relatively dense structure.

[0036] Figure 3 This is the fracture morphology of the SiC / SiC-Yb2Si2O7 composite material prepared in this example after being oxidized by water and oxygen at 1200 °C for 80 h. It can be seen from the figure that fiber pullout and crack deflection are still present after oxidation.

[0037] Example 2 The difference from Example 1 is the preparation of the impregnation slurry: 15 g SiC powder (300 nm particle size), 15 g Yb2Si2O7 powder (300 nm particle size), 45 g anhydrous ethanol, 3 g fish oil, 1.5 g polyvinyl butyral and 1.5 g phenolic resin are mixed.

[0038] The SiC / SiC-Yb2Si2O7 composite material prepared in this example has a dense structure and a bending strength of 474 MPa.

[0039] Figure 4 This is a cross-sectional morphology of the SiC / SiC-Yb2Si2O7 composite material prepared in this example. As can be seen from the figure, the SiC / SiC-Yb2Si2O7 composite material exhibits a relatively dense structure.

[0040] Comparative Example 1 The difference from Example 1 is the preparation of the impregnation slurry: 30 g SiC powder (300 nm particle size), 45 g anhydrous ethanol, 3 g fish oil, 1.5 g polyvinyl butyral and 1.5 g phenolic resin are mixed.

[0041] The SiC / SiC composite material prepared in this comparative example has a flexural strength of 477 MPa, and a strength retention rate of 63.3% after water-oxygen oxidation at 1200°C for 80 hours.

[0042] Figure 5 This is the fracture morphology of the SiC / SiC composite material prepared in this comparative example after being oxidized by water and oxygen at 1200 °C for 80 h. It can be seen from the figure that the fiber pull-out becomes significantly shorter after oxidation.

[0043] The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. The above embodiment of the present invention can also be modified in various ways. That is, all simple, equivalent changes and modifications made according to the claims and the description of the present invention fall within the scope of protection of the claims of the present invention. The contents not described in detail in the present invention are all conventional technical contents.

Claims

1. A method for preparing a SiC / SiC composite material, characterized in that: The preparation method comprises the following steps: S1, forming a single layer or multilayer interface on SiC fiber; S2, mixing SiC powder and rare earth silicate powder in a mass ratio of 1: (0.05-10) to obtain a mixed powder, ball milling the mixed powder in a mass ratio of mixed powder: solvent: dispersant: binder: curing agent = 1: (0.5-3): (0.02-0.3): (0.02-0.2): (0.02-0.2) to provide an impregnation slurry, immersing the fiber after the interface is formed in the impregnation slurry for vacuum impregnation, heating and curing to fix the slurry, heating and cracking to remove organic matter and simultaneously forming a porous structure to obtain a SiC / SiC composite material with a porous matrix; as well as S3, generating SiC by polymer precursor impregnation pyrolysis method for matrix densification.

2. The preparation method according to claim 1, characterized in that: The interface is a BN interface, a PyC interface, or a BN / SiC multilayer interface.

3. The preparation method according to claim 1, characterized in that: The rare earth silicate is one or more of Yb2Si2O7, Y2Si2O7, Ho2Si2O7, Yb2SiO5, Y2SiO5, or Ho2SiO5.

4. The preparation method according to claim 1, characterized in that: The impregnation slurry is obtained by ball milling the mixture for 12 to 120 h in a polytetrafluoroethylene ball mill, and the ball milling medium is SiC ball.

5. The preparation method according to claim 1, characterized in that: In step S2, vacuum impregnation is performed in a vacuum impregnation tank for 0.5 to 5 h, curing is performed in a high temperature oven at 80 to 120 °C for 10 to 30 h, and pyrolysis is performed in a vacuum carbon tube furnace at 700 to 1100 °C for 0.5 to 3 h.

6. The preparation method according to claim 1, characterized in that: The precursor is polycarbosilane or polydimethylsilane.

7. The preparation method according to claim 1, characterized in that: In step S3, the SiC / SiC composite material is vacuum impregnated with a precursor, and the precursor is cracked under an inert gas to obtain SiC to increase density.

8. The preparation method according to claim 7, characterized in that: The pyrolysis conditions of the precursor are 800~1200 ℃, 0.5~5 h.

9. A composite material obtained by the preparation method according to any one of claims 1 to 8.

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