Method for connecting silicon-based high-temperature brazing filler metal with SiCf / SiC composite material

Abstract

The invention discloses a method for connecting SiCf / SiC composite materials through silicon-based high-temperature brazing filler metal, and belongs to the technical field of brazing. The method comprises the following steps: (1) preparing a Si-Pr high-temperature brazing material (12 at.%-25 at.% of Pr and 75 at.%-88 at.% of Si) by adopting electric arc melting, carrying out linear cutting on a cast and cooled Si-Pr cast ingot to obtain flaky brazing filler metal, and removing a surface oxide layer; (2) the to-be-connected base material of the SiCf / SiC composite material is subjected to pretreatment such as grinding and polishing; and (3) the Si-Pr high-temperature brazing filler metal is placed between the SiCf / SiC composite material base materials, the Si-Pr high-temperature brazing filler metal is placed in a brazing furnace in a sandwich structure, brazing connection is completed through staged heating and heat preservation, and a continuous and compact layered MAX-phase Pr3Si2C2 transition layer is formed on an interface in situ. The gradient transition layer is formed through the connecting method, the strength of the connector can be enhanced, and the oxidation resistance of the connector is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of brazing, and particularly relates to a method for connecting SiCf / SiC composite materials by using silicon-based high-temperature brazing filler. BACKGROUND

[0002] SiCf / SiC composite materials have the advantages of high high-temperature strength, low density, excellent oxidation resistance, etc., and have become important candidate structural materials in advanced aerospace systems in the field of aerospace, and have broad application prospects. However, due to the complex shape of SiCf / SiC components and the difficulty in direct forming, the connection technology of SiCf / SiC composite materials still faces challenges. When connecting SiCf / SiC composite materials by using traditional mechanical connection or brazing method, there are problems such as insufficient joint strength, poor oxidation resistance, etc. Although the mechanical connection method is simple to operate, it may cause stress concentration, reduce the performance of the joint, and easily cause creep failure in a high-temperature environment; although the traditional brazing method can realize the connection of materials, due to the poor wettability of the brazing filler and SiC material, the brazing filler is easily corroded in a high-temperature oxidation environment, resulting in insufficient joint strength and high-temperature resistance, which is difficult to meet the harsh requirements in the field of aerospace. These problems seriously limit the application of SiCf / SiC composite materials.

[0003] At present, it is urgent to develop a method for connecting SiCf / SiC composite materials with effectively improved joint strength and high-temperature resistance, so as to promote the wide application of SiCf / SiC composite materials. SUMMARY

[0004] In view of the problems existing in the prior art, the application aims to provide a method for connecting SiCf / SiC composite materials by using silicon-based high-temperature brazing filler, which can significantly improve the high-temperature strength and oxidation resistance of the joint by optimizing the composition and microstructure of the brazing material, introducing an additive element with excellent oxidation resistance, and forming a dense oxide film to effectively prevent the oxidation reaction; at the same time, an interface functional transition layer RE3Si2C2 (RE is a rare earth element) with a similar expansion coefficient to SiC is constructed in situ during the brazing process, which has potential interface buffering and toughening capacity, and can significantly improve the high-temperature strength retention rate and oxidation resistance durability of the joint; by optimizing the brazing process parameters, the high-temperature tensile strength of the joint is improved, and the joint shows good durability in an oxidation environment.

[0005] The purpose of the application is achieved by the following technical scheme:

[0006] The application provides a method for connecting SiCf / SiC composite materials by using silicon-based high-temperature brazing filler, which comprises the following steps:

[0007] (1) preparing Si-Pr high-temperature brazing material by using arc melting method;

[0008] (2) Pretreatment of SiCf / SiC composite material base material to be connected;

[0009] (3) SiCf / SiC composite material is connected by using Si-Pr high-temperature brazing material.

[0010] Further, step (1) adopts the electric arc smelting method to prepare the Si-Pr high-temperature brazing material, including the following steps:

[0011] (1) The Si and Pr raw materials with purity ≥99.9wt% are cleaned, weighed according to the proportion, and then placed in a vacuum arc furnace for electric arc smelting, and then the arc is turned off for cooling and re-melting 3-5 times to ensure uniform composition and control the quality loss within 2.0wt%;

[0012] (2) The Si-Pr alloy after electric arc smelting is cast to obtain Si-Pr ingot after cooling;

[0013] (3) The Si-Pr ingot is cut into a sheet-shaped filler material by using a wire cutting method, and the surface oxide layer is removed, and the silicon-based high-temperature filler material foil is obtained after cleaning and drying.

[0014] Further, in step (1) of preparing the Si-Pr high-temperature brazing material, the raw materials are weighed according to the target composition of Pr 12at.%-25at.% and Si 75at.%-88at.%;

[0015] The temperature is controlled at 1400℃-1550℃ and the time is controlled at 10s-30s for each electric arc smelting.

[0016] Further, in step (3) of preparing the Si-Pr high-temperature brazing material, the thickness of the sheet-shaped filler material after cutting the Si-Pr ingot is 500μm-600μm;

[0017] The surface oxide layer is removed by grinding the sheet-shaped filler material to a thickness of 300μm-400μm using sandpaper from coarse to fine, and then polishing treatment is performed;

[0018] The cleaning is performed by using alcohol for ultrasonic cleaning.

[0019] Further, the sandpaper used for grinding the sheet-shaped filler material is 400#, 800#, 1500# and 2000# sandpaper in turn from coarse to fine;

[0020] The polishing agent used for polishing treatment is SiO2-H2O2;

[0021] The cleaning time is 10min-20min.

[0022] Further, in the pretreatment of the SiCf / SiC composite material to be connected in step (2), the SiCf / SiC composite material to be connected is wire cut into a required size, and the surface of the SiCf / SiC composite material to be connected is polished by using sandpaper from coarse to fine, and then is cleaned and dried.

[0023] Further, the sandpaper from coarse to fine for polishing the SiCf / SiC composite material is 80#, 400#, 800#, 1200# and 3000# in sequence.

[0024] The polishing agent used in the polishing treatment is SiO2-H2O2.

[0025] The cleaning is ultrasonic cleaning for 10 min-20 min by using alcohol.

[0026] Further, in the brazing connection in step (3), a silicon-based high-temperature brazing filler metal foil is arranged between the pretreated SiCf / SiC composite materials to be connected to form a sandwich structure, and is fixed by using an organic adhesive, and then is placed in a mold and is put into a brazing furnace, and is heated and kept in stages under vacuum or inert atmosphere, and a continuous and dense layered MAX phase Pr3Si2C2 transition layer is formed in situ at the interface, and is cooled to room temperature in the furnace, and the brazing connection is completed.

[0027] Further, the organic adhesive for brazing the SiCf / SiC composite material is pine oil alcohol containing 10 wt.% ethyl cellulose.

[0028] The heating in stages is two-stage heating from low to high, and the first stage is heated to 300℃-350℃ at a heating rate of 5℃ / min-10℃ / min, and is kept for 10 min-30 min to remove the organic adhesive; and the second stage is heated to a brazing temperature of 1250℃-1400℃ at a heating rate of 5℃ / min-10℃ / min, and is kept for 5 min-20 min.

[0029] Further, the thickness of the MAX phase Pr3Si2C2 transition layer is 5μm-20μm.

[0030] Advantages and effects of the present application:

[0031] The silicon-based high-temperature brazing material prepared by the method can react with the SiCf / SiC composite material to form a dense and stable SiC reaction interface layer MAX phase Pr3Si2C2, which has both metallic properties (good electrical conductivity, heat conductivity and certain processability) and ceramic properties (corrosion resistance and high temperature resistance), thereby significantly reducing residual stress and inhibiting through brittle cracking; meanwhile, the moderate elastic modulus and excellent electrical / thermal conductivity make the cross-border transmission of mechanics and functions smoother, facilitating the formation of a thin and continuous gradient transition layer, enhancing the joint strength and improving the oxidation resistance of the joint, thereby providing an effective method for connecting SiCf / SiC composite material components in the aerospace field under high-temperature environments, and further promoting the wide application of SiCf / SiC composite materials. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The scanning electron microscope (SEM) morphology diagram of the Si-Pr high-temperature brazing material prepared for Example 1 infiltrating the interface is shown in (a) and (b), wherein (a) is a morphology diagram showing the infiltration angle, and (b) is a morphology diagram showing the Pr3Si2C2 phase reaction layer.

[0033] Figure 2 The energy dispersive X-ray spectroscopy (EDS) diagram of the weld after welding of Example 1 is shown in (a), (b), (c) and (d), wherein (a) is an EDS layered image, (b) is a Si element surface distribution diagram, (c) is a Pr element surface distribution diagram, and (d) is a C element surface distribution diagram.

[0034] Figure 3 The scanning electron microscope (SEM) morphology diagram of the weld after welding of Example 1 is shown in (a) and (b). DETAILED DESCRIPTION

[0035] The specific embodiments of the present application will be further described in detail below in combination with the drawings and examples.

[0036] The present application provides a method for connecting SiCf / SiC composite material by using silicon-based high-temperature brazing material, which comprises the following steps:

[0037] (1) The Si-Pr high-temperature brazing material is prepared by using arc melting method, which specifically comprises:

[0038] 1) The Si and Pr raw materials with a purity of ≥99.9wt% are subjected to cleaning treatment, and the raw materials are weighed according to the target composition of Pr 12at.%-25at.% and Si 75at.%-88at.%, and then placed in a vacuum arc furnace for arc melting, with the temperature controlled at 1400℃-1550℃ and the time controlled at 10s-30s, and then the arc is turned off for cooling and the sample is turned over for 3-5 times of remelting to ensure uniform composition and control the mass loss within 2.0wt%;

[0039] 2) Casting the Si-Pr alloy after arc melting, and obtaining Si-Pr ingot after cooling;

[0040] 3) Cutting the Si-Pr ingot into sheet-shaped filler material with a thickness of 500 μm-600 μm by using a wire cutting method; polishing the sheet-shaped filler material to a thickness of 300 μm-400 μm by using 400#, 800#, 1500# and 2000# sandpaper in sequence, and then performing polishing treatment by using a polishing agent SiO2-H2O2, removing the oxide layer, and performing ultrasonic cleaning by using alcohol for 10 min-20 min, and obtaining a silicon-based high-temperature filler material foil after drying.

[0041] (2) Pretreatment of the SiCf / SiC composite material base material to be connected: cutting the SiCf / SiC composite material base material to be connected into a required size by using a wire cutting method, polishing the surface of the SiCf / SiC composite material base material to be connected by using 80#, 400#, 800#, 1200# and 3000# sandpaper in sequence, and then performing polishing treatment by using a SiO2-H2O2 polishing agent, and drying after ultrasonic cleaning by using alcohol for 10 min-20 min.

[0042] (3) SiCf / SiC composite material is connected by using Si-Pr high-temperature brazing material: placing the silicon-based high-temperature filler material foil between the pretreated SiCf / SiC composite material base material to be connected to form a sandwich structure, and fixing by using an organic adhesive containing 10 wt.% ethyl cellulose in pine oil, and then placing in a mold, and then placing in a brazing furnace, and first heating to 300℃-350℃ at a heating rate of 5℃ / min-10℃ / min under vacuum or inert atmosphere, and then heating to 1250℃-1400℃ at a heating rate of 5℃ / min-10℃ / min, and then holding for 5 min-20 min, and then forming a continuous and dense layered MAX phase Pr3Si2C2 transition layer in situ at the interface, and then cooling to room temperature in the furnace, and then completing the brazing connection.

[0043] Example 1

[0044] The application provides a method for connecting SiCf / SiC composite material by using silicon-based high-temperature filler material, which comprises the following steps:

[0045] (1) The Si-Pr high-temperature brazing material is prepared by using an arc melting method, and specifically comprises the following steps:

[0046] 1) The Si and Pr raw materials with a purity of 99.9wt% are cleaned, and the raw materials with a target composition of Pr 17at.% and Si 83at.% are weighed and placed in a vacuum arc furnace for arc melting, with a temperature of 1400°C and a time of 10s, and then the arc is turned off for cooling and re-melting by turning over 3 times to ensure uniform composition, with a mass loss controlled within 2.0wt%;

[0047] 2) The Si-Pr alloy after arc melting is cast to obtain a Si-Pr ingot after cooling;

[0048] 3) The Si-Pr ingot is cut into a sheet-shaped filler material with a thickness of 500μm by wire cutting, and the sheet-shaped filler material is polished to a thickness of 300μm by using 400#, 800#, 1500# and 2000# sandpaper in sequence, and then polished by using a polishing agent of SiO2-H2O2 to remove the oxide layer, and ultrasonic cleaned with alcohol for 10min, and dried after blowing to obtain a silicon-based high-temperature filler material foil.

[0049] (2) Pretreatment of the SiCf / SiC composite material to be connected: the SiCf / SiC composite material to be connected is wire cut to the required size, and the surface of the SiCf / SiC composite material to be connected is polished by using 80#, 400#, 800#, 1200# and 3000# sandpaper in sequence, and then polished by using a SiO2-H2O2 polishing agent, and ultrasonic cleaned with alcohol for 10min and dried.

[0050] (3) Si-Pr high-temperature brazing material is used to braze and connect the SiCf / SiC composite material: the silicon-based high-temperature filler material foil is placed between the pretreated SiCf / SiC composite material to be connected to form a sandwich structure, and is fixed by an organic adhesive containing 10wt.% ethyl cellulose in pine oil, and then placed in a mold and put into a brazing furnace, and first heated to 350°C at a heating rate of 5°C / min under vacuum, and then heated to 1300°C at a heating rate of 5°C / min, and held for 15min, and a continuous and dense layered MAX phase Pr3Si2C2 transition layer is formed in situ at the interface, with a thickness of 17μm, and the furnace is cooled to room temperature to complete the brazing connection.

[0051] Performance test:

[0052] Wetting analysis:

[0053] The filler material prepared in step (1) is placed on the base material after being held at 1300°C for 15min, and the wetting interface microstructure is observed, as shown in Figure 1 (a), the filler material wets well on the base material, forming a wetting angle of about 15°; as Figure 1(b) as shown, a layer-like flaky Pr3Si2C2 phase reaction layer appears at the interface, indicating that a reaction layer is formed between the filler metal and the base material through chemical reaction, thereby realizing effective bonding.

[0054] Welding performance analysis:

[0055] The Si-Pr eutectic filler metal of this embodiment 1 successfully realizes welding after holding at 1300℃ for 15 min. Through EDS and SEM tests, the weld after welding is observed, as shown in Figure 2 , it can be seen that a typical Si-Pr eutectic phase is formed at the weld; as shown in Figure 3 , a gray long strip area appears on both sides of the weld, forming a ternary MAX phase Pr3Si2C2 connecting layer, and the filler metal does not diffuse to the base material in large quantities. In addition, the strength test shows that the strength of the welded joint is 15 MPa, indicating that the filler metal has good bonding performance.

[0056] Example 2

[0057] The present application provides a method for connecting SiCf / SiC composite material by using silicon-based high-temperature filler metal, comprising the following steps:

[0058] (1) Si-Pr high-temperature brazing material is prepared by arc melting method, specifically including:

[0059] 1) The Si and Pr raw materials with a purity of 99.9wt% are cleaned, and the raw materials are weighed according to the target composition of Pr 12at.% and Si 88at.% and placed in a vacuum arc furnace for arc melting, with the temperature controlled at 1520℃ and the time controlled at 20s, then the arc is turned off for cooling and the ingot is flipped and remelted for 5 times to ensure uniform composition, and the mass loss is controlled within 2.0wt%;

[0060] 2) The Si-Pr alloy after arc melting is cast, and the Si-Pr ingot is obtained after cooling;

[0061] 3) The Si-Pr ingot is cut into a sheet-shaped filler metal with a thickness of 500μm by wire cutting method; the sheet-shaped filler metal is polished to a thickness of 400μm by using 400#, 800#, 1500# and 2000# sandpaper in turn, and then polished by using a polishing agent SiO2-H2O2 to remove the oxide layer, and cleaned by ultrasonic cleaning with alcohol for 10 min, and then dried to obtain a silicon-based high-temperature filler metal foil.

[0062] (2) Pretreatment of SiCf / SiC composite base material to be connected: the SiCf / SiC composite base material to be connected is wire cut to the required size, the surface of the SiCf / SiC composite base material to be connected is polished using 80#, 400#, 800#, 1200# and 3000# sandpaper in turn, and then polished using SiO2-H2O2 polishing agent, and then dried after ultrasonic cleaning with alcohol for 10 min.

[0063] (3) Brazing connection of SiCf / SiC composite material using Si-Pr high-temperature brazing material: the silicon-based high-temperature filler metal foil is placed between the pretreated SiCf / SiC composite base material to be connected to form a sandwich structure, and then fixed by an organic adhesive containing 10 wt.% ethyl cellulose in pine oil, and then placed in a mold and then placed in a brazing furnace, and then heated to 350°C at a heating rate of 5°C / min under vacuum, and then heated to 1250°C at a heating rate of 5°C / min, and then held for 5 min, and then a continuous and dense layered MAX phase Pr3Si2C2 transition layer is formed in situ at the interface, the thickness of the transition layer is 5 μm, and the brazing connection is completed by cooling to room temperature in the furnace.

[0064] Example 3

[0065] The application provides a method for connecting SiCf / SiC composite material by using silicon-based high-temperature filler metal, which comprises the following steps:

[0066] (1) The Si-Pr high-temperature brazing material is prepared by arc melting method, which specifically comprises:

[0067] 1) The Si and Pr raw materials with a purity of 99.9 wt% are cleaned, the raw materials are weighed according to the target composition of Pr 25 at.% and Si 75 at.%, and then placed in a vacuum arc furnace for arc melting, the temperature is controlled to be 1510°C, the time is controlled to be 10 s, then the arc is turned off for cooling and the ingot is remelted for 5 times by turning over to ensure the uniformity of the composition, and the mass loss is controlled to be less than 2.0 wt%;

[0068] 2) The Si-Pr alloy after arc melting is cast, and the Si-Pr ingot is obtained after cooling;

[0069] 3) The Si-Pr ingot is cut into a sheet-shaped filler metal with a thickness of 500 μm by using a wire cutting method; the sheet-shaped filler metal is polished to a thickness of 300 μm by using 400#, 800#, 1500# and 2000# sandpaper in turn, and then polished by using a polishing agent SiO2-H2O2 to remove the oxide layer, and then ultrasonic cleaned with alcohol for 10 min, and then dried to obtain a silicon-based high-temperature filler metal foil.

[0070] (2) Pretreatment of SiCf / SiC composite base material to be connected: the SiCf / SiC composite base material to be connected is wire cut to the required size, the surface of the SiCf / SiC composite base material to be connected is polished using 80#, 400#, 800#, 1200# and 3000# sandpaper in turn, and then polished using SiO2-H2O2 polishing agent, and then dried after ultrasonic cleaning with alcohol for 10 min.

[0071] (3) Brazing connection of SiCf / SiC composite material using Si-Pr high-temperature brazing material: the silicon-based high-temperature filler metal foil is placed between the pretreated SiCf / SiC composite base material to be connected to form a sandwich structure, and then fixed by an organic binder containing 10 wt.% ethyl cellulose in pine oil, and then placed in a mold and then placed in a brazing furnace, and then heated to 300°C at a heating rate of 5°C / min under an argon atmosphere, and then held for 20 min, and then heated to 1300°C at a heating rate of 5°C / min, and then held for 15 min, and then a continuous and dense layered MAX phase Pr3Si2C2 transition layer is formed in situ at the interface, the thickness of the transition layer is 18 μm, and the brazing connection is completed by cooling to room temperature in the furnace.

[0072] Example 4

[0073] The application provides a method for connecting SiCf / SiC composite material by using silicon-based high-temperature filler metal, which comprises the following steps:

[0074] (1) The Si-Pr high-temperature brazing material is prepared by using an arc melting method, and specifically comprises the following steps:

[0075] 1) The Si and Pr raw materials with a purity of 99.9 wt% are cleaned, the raw materials are weighed according to the target composition of Pr 25 at.% and Si 75 at.%, and then placed in a vacuum arc furnace for arc melting, the temperature is controlled to be 1550°C, the time is controlled to be 15 s, then the arc is turned off for cooling and the ingot is remelted for 5 times by turning over to ensure uniform composition, and the mass loss is controlled to be within 2.0 wt%;

[0076] 2) The Si-Pr alloy after arc melting is cast, and the Si-Pr ingot is obtained after cooling;

[0077] 3) The Si-Pr ingot is cut into a sheet-shaped filler metal with a thickness of 500 μm by using a wire cutting method, the sheet-shaped filler metal is polished to a thickness of 300 μm by using 400#, 800#, 1500# and 2000# sandpaper in turn, and then polished by using a polishing agent SiO2-H2O2 to remove the oxide layer, and then ultrasonic cleaned with alcohol for 20 min, and then dried to obtain a silicon-based high-temperature filler metal foil.

[0078] (2) Pretreatment of SiCf / SiC composite base material to be connected: the SiCf / SiC composite base material to be connected is wire cut to the required size, the surface of the SiCf / SiC composite base material to be connected is polished using 80#, 400#, 800#, 1200# and 3000# sandpaper in turn, and then polished using SiO2-H2O2 polishing agent, and then dried after ultrasonic cleaning with alcohol for 10 min.

[0079] (3) Brazing connection of SiCf / SiC composite material using Si-Pr high-temperature brazing material: the silicon-based high-temperature filler metal foil is placed between the pretreated SiCf / SiC composite base material to be connected to form a sandwich structure, and then fixed by an organic binder containing 10 wt.% ethyl cellulose in pine oil, and then placed in a mold and then placed in a brazing furnace, and then heated to 330°C at a heating rate of 5°C / min under vacuum, and then heated to 1380°C at a heating rate of 5°C / min, and then held for 20 min, and then a continuous and dense layered MAX phase Pr3Si2C2 transition layer is formed in situ at the interface, the thickness of the transition layer is 20 μm, and the brazing connection is completed by cooling to room temperature in the furnace.

[0080] Example 5

[0081] The application provides a method for connecting SiCf / SiC composite material by using silicon-based high-temperature filler metal, which comprises the following steps:

[0082] (1) The Si-Pr high-temperature brazing material is prepared by arc melting method, which specifically comprises the following steps:

[0083] 1) The Si and Pr raw materials with a purity of 99.9 wt% are cleaned, the raw materials are weighed according to the target composition of Pr 24 at.% and Si 76 at.%, and then placed in a vacuum arc furnace for arc melting, the temperature is controlled to be 1520°C, the time is controlled to be 10 s, then the arc is turned off for cooling and the ingot is remelted for 5 times by turning over to ensure the uniformity of the composition, and the mass loss is controlled to be less than 2.0 wt%;

[0084] 2) The Si-Pr alloy after arc melting is cast, and the Si-Pr ingot is obtained after cooling;

[0085] 3) The Si-Pr ingot is cut into a sheet-shaped filler metal with a thickness of 600 μm by using a wire cutting method, the sheet-shaped filler metal is polished to a thickness of 300 μm by using 400#, 800#, 1500# and 2000# sandpaper in turn, and then polished by using a polishing agent SiO2-H2O2 to remove the oxide layer, and then ultrasonic cleaned with alcohol for 10 min, and then dried to obtain a silicon-based high-temperature filler metal foil.

[0086] (2) Pretreatment of SiCf / SiC composite base material to be connected: the SiCf / SiC composite base material to be connected is wire cut to the required size, the surface of the SiCf / SiC composite base material to be connected is polished using 80#, 400#, 800#, 1200# and 3000# sandpaper in turn, and then polished using SiO2-H2O2 polishing agent, and then dried after ultrasonic cleaning with alcohol for 10 min.

[0087] (3) Brazing connection of SiCf / SiC composite material using Si-Pr high-temperature brazing material: the silicon-based high-temperature filler metal foil is placed between the pretreated SiCf / SiC composite base material to be connected to form a sandwich structure, and then fixed by an organic binder containing 10 wt.% ethyl cellulose in pine oil, and then placed in a mold and then placed in a brazing furnace, and then heated to 300℃ at a heating rate of 5℃ / min under vacuum, and then heated to 1400℃ at a heating rate of 10℃ / min, and then held for 5 min, and then a continuous and dense layered MAX phase Pr3Si2C2 transition layer is formed in situ at the interface, the thickness of the transition layer is 25μm, and the brazing connection is completed by cooling to room temperature in the furnace.

[0088] Example 6

[0089] The application provides a method for connecting SiCf / SiC composite material by using silicon-based high-temperature filler metal, which comprises the following steps:

[0090] (1) The Si-Pr high-temperature brazing material is prepared by arc melting method, which specifically comprises:

[0091] 1) The Si and Pr raw materials with a purity of 99.9wt% are cleaned, the raw materials are weighed according to the target composition of Pr 20at.% and Si 80at.%, and then placed in a vacuum arc furnace for arc melting, the temperature is controlled to be 1550℃, the time is controlled to be 10s, then the arc is turned off for cooling and the ingot is remelted for 5 times by turning over to ensure the uniformity of the composition, and the mass loss is controlled to be within 2.0wt%;

[0092] 2) The Si-Pr alloy after arc melting is cast, and the Si-Pr ingot is obtained after cooling;

[0093] 3) The Si-Pr ingot is cut into a sheet-shaped filler metal with a thickness of 600μm by using a wire cutting method, the sheet-shaped filler metal is polished to a thickness of 300μm by using 400#, 800#, 1500# and 2000# sandpaper in turn, and then polished by using a polishing agent SiO2-H2O2 to remove the oxide layer, and then ultrasonic cleaned with alcohol for 20 min, and then dried to obtain a silicon-based high-temperature filler metal foil.

[0094] (2) Pretreatment of SiCf / SiC composite base material to be connected: the SiCf / SiC composite base material to be connected is wire cut to the required size, the surface of the SiCf / SiC composite base material to be connected is polished using 80#, 400#, 800#, 1200# and 3000# sandpaper in turn, and then polished using SiO2-H2O2 polishing agent, and then dried after ultrasonic cleaning with alcohol for 10 min.

[0095] (3) Brazing connection of SiCf / SiC composite material using Si-Pr high-temperature brazing material: the silicon-based high-temperature filler metal foil is placed between the pretreated SiCf / SiC composite base material to be connected to form a sandwich structure, and then fixed by an organic adhesive containing 10 wt.% ethyl cellulose in pine oil, and then placed in a mold and then placed in a brazing furnace, and then heated to 340°C at a heating rate of 10°C / min under vacuum, and then held for 20 min, and then heated to 1320°C at a heating rate of 5°C / min, and then held for 10 min, and then a continuous and dense layered MAX phase Pr3Si2C2 transition layer is formed in situ at the interface, the thickness of the transition layer is 18 μm, and the brazing connection is completed by cooling to room temperature in the furnace.

[0096] Example 7

[0097] The application provides a method for connecting SiCf / SiC composite material by using silicon-based high-temperature filler metal, which comprises the following steps:

[0098] (1) The Si-Pr high-temperature brazing material is prepared by arc melting method, which specifically comprises the following steps:

[0099] 1) The Si and Pr raw materials with a purity of 99.9 wt% are cleaned, the raw materials are weighed according to the target composition of Pr 15 at.% and Si 85 at.%, and then placed in a vacuum arc furnace for arc melting, the temperature is controlled to be 1540°C, the time is controlled to be 15 s, then the arc is turned off for cooling and the ingot is remelted for 5 times by turning over to ensure the uniformity of the composition, and the mass loss is controlled to be less than 2.0 wt%;

[0100] 2) The Si-Pr alloy after arc melting is cast, and the Si-Pr ingot is obtained after cooling;

[0101] 3) The Si-Pr ingot is cut into a sheet-shaped filler metal with a thickness of 600 μm by using a wire cutting method, the sheet-shaped filler metal is polished to a thickness of 300 μm by using 400#, 800#, 1500# and 2000# sandpaper in turn, and then polished by using a polishing agent SiO2-H2O2 to remove the oxide layer, and then ultrasonic cleaned with alcohol for 20 min, and then dried to obtain a silicon-based high-temperature filler metal foil.

[0102] (2) Pretreatment of SiCf / SiC composite base material to be connected: the SiCf / SiC composite base material to be connected is wire cut to the required size, the surface of the SiCf / SiC composite base material to be connected is polished using 80#, 400#, 800#, 1200# and 3000# sandpaper in turn, and then polished using SiO2-H2O2 polishing agent, and then dried after ultrasonic cleaning with alcohol for 10 min.

[0103] (3) Brazing connection of SiCf / SiC composite material using Si-Pr high-temperature brazing material: the silicon-based high-temperature filler metal foil is placed between the pretreated SiCf / SiC composite base material to be connected to form a sandwich structure, and then fixed by an organic adhesive containing 10 wt.% ethyl cellulose in pine oil, and then placed in a mold and then placed in a brazing furnace, and then heated to 300°C at a heating rate of 5°C / min under vacuum, and then heated to 1330°C at a heating rate of 5°C / min, and then held for 10 min, and then a continuous and dense layered MAX phase Pr3Si2C2 transition layer is formed in situ at the interface, the thickness of the transition layer is 18 μm, and the brazing connection is completed by cooling to room temperature in the furnace.

[0104] Example 8

[0105] The application provides a method for connecting SiCf / SiC composite material by using silicon-based high-temperature filler metal, which comprises the following steps:

[0106] (1) The Si-Pr high-temperature brazing material is prepared by arc melting method, which specifically comprises the following steps:

[0107] 1) The Si and Pr raw materials with a purity of 99.9 wt% are cleaned, the raw materials are weighed according to the target composition of Pr 15 at.% and Si 85 at.%, and then placed in a vacuum arc furnace for arc melting, the temperature is controlled to be 1530°C, the time is controlled to be 30 s, then the arc is turned off for cooling and the ingot is remelted for 3 times by turning over to ensure the uniformity of the composition, and the mass loss is controlled to be less than 2.0 wt%;

[0108] 2) The Si-Pr alloy after arc melting is cast, and the Si-Pr ingot is obtained after cooling;

[0109] 3) The Si-Pr ingot is cut into a sheet-shaped filler metal with a thickness of 600 μm by using a wire cutting method; the sheet-shaped filler metal is polished to a thickness of 300 μm by using 400#, 800#, 1500# and 2000# sandpaper in turn, and then polished by using a polishing agent SiO2-H2O2 to remove the oxide layer, and then ultrasonic cleaned with alcohol for 20 min, and then dried to obtain a silicon-based high-temperature filler metal foil.

[0110] (2) Pretreatment of SiCf / SiC composite base material to be connected: The SiCf / SiC composite base material to be connected is wire cut to the required size, the surface of the SiCf / SiC composite base material to be connected is polished using 80#, 400#, 800#, 1200# and 3000# sandpaper in turn, and then polished using SiO2-H2O2 polishing agent, and then ultrasonic cleaned using alcohol for 20 min and dried.

[0111] (3) Brazing connection of SiCf / SiC composite using Si-Pr high-temperature brazing material: The silicon-based high-temperature brazing material foil is placed between the pretreated SiCf / SiC composite base materials to be connected to form a sandwich structure, and then fixed by an organic binder containing 10 wt.% ethyl cellulose in terpineol, and then placed in a mold, and then placed in a brazing furnace, and then heated to 350°C at a heating rate of 10°C / min under vacuum, and then held for 30 min, and then heated to 1310°C at a heating rate of 5°C / min, and then held for 10 min, and then a continuous and dense layered MAX phase Pr3Si2C2 transition layer is formed in situ at the interface, the thickness of the transition layer is 17 μm, and then the furnace is cooled to room temperature, and the brazing connection is completed.

Claims

1. A method for joining SiCf / SiC composite materials with silicon-based high-temperature solder, characterized in that, Includes the following steps: (1) Si-Pr high-temperature brazing material was prepared by electric arc melting method; (2) Pretreatment of the SiCf / SiC composite material base material to be joined; (3) Using Si-Pr high-temperature brazing material to braze SiCf / SiC composite material.

2. The method for joining SiCf / SiC composite materials with silicon-based high-temperature solder as described in claim 1, characterized in that, Step (1) involves preparing Si-Pr high-temperature brazing material using an electric arc melting method, including the following steps: (1) Clean the Si and Pr raw materials with a purity of ≥99.9wt%, weigh them according to the proportion, place them in a vacuum electric arc furnace, perform electric arc melting, then turn off the arc to cool and remelt them 3-5 times, and control the mass loss to within 2.0wt%. (2) Cast the Si-Pr alloy after arc melting, and obtain Si-Pr ingots after cooling; (3) The Si-Pr ingot is cut into sheet-like brazing filler metal by wire cutting, and the surface oxide layer is removed. After cleaning and drying, silicon-based high-temperature brazing filler metal foil is obtained.

3. The method for joining SiCf / SiC composite materials with silicon-based high-temperature solder as described in claim 2, characterized in that, In step (1) of preparing Si-Pr high-temperature brazing material, the raw materials are weighed with the target composition Pr 12at.%-25at.% and Si 75at.%-88at.%; Each electric arc melting process is controlled at a temperature of 1400℃-1550℃ for 10s-30s.

4. The method for joining SiCf / SiC composite materials with silicon-based high-temperature solder as described in claim 2, characterized in that, In step (3) of preparing Si-Pr high-temperature brazing material, the thickness of the sheet brazing filler metal after cutting the Si-Pr ingot is 500μm-600μm. To remove the surface oxide layer, the sheet solder is sanded with sandpaper of varying coarseness to a thickness of 300μm-400μm, followed by polishing. The cleaning process involves ultrasonic cleaning with alcohol.

5. The method for joining SiCf / SiC composite materials with silicon-based high-temperature solder as described in claim 4, characterized in that, The sandpaper used for polishing sheet-shaped brazing filler metal, from coarse to fine, is 400#, 800#, 1500#, and 2000# sandpaper, respectively. The polishing agent used in the polishing process is SiO2-H2O2; The cleaning time is 10-20 minutes.

6. The method for joining SiCf / SiC composite materials with silicon-based high-temperature solder as described in claim 1, characterized in that, In step (2), the SiCf / SiC composite material base material to be joined is pretreated by wire cutting to the required size, and the surface of the SiCf / SiC composite material base material to be joined is sanded and polished with sandpaper from coarse to fine, and then cleaned and dried.

7. The method for joining SiCf / SiC composite materials with silicon-based high-temperature solder as described in claim 6, characterized in that, The sandpaper used for grinding SiCf / SiC composite matrix, from coarse to fine, is 80#, 400#, 800#, 1200#, and 3000#. The polishing agent used in the polishing process is SiO2-H2O2; The cleaning process involves ultrasonic cleaning with alcohol for 10-20 minutes.

8. The method for joining SiCf / SiC composite materials with silicon-based high-temperature solder as described in claim 1, characterized in that, Step (3) Brazing involves placing silicon-based high-temperature brazing foil between the pretreated SiCf / SiC composite material base materials to be joined, forming a sandwich structure, fixing it with an organic adhesive, then placing it in a mold, and then placing it in a brazing furnace. Under vacuum or inert atmosphere, it is heated and kept warm in stages to form a continuous and dense layered MAX phase Pr3Si2C2 transition layer in situ at the interface. The furnace is then cooled to room temperature to complete the brazing connection.

9. The method for joining SiCf / SiC composite materials with silicon-based high-temperature solder as described in claim 8, characterized in that, The organic binder for brazing SiCf / SiC composite materials is terpineol containing 10 wt.% ethyl cellulose; The staged heating process involves two phases of heating and holding, from low to high. In the first phase, the temperature is raised to 300℃-350℃ at a rate of 5℃ / min-10℃ / min and held for 10min-30min. In the second phase, the temperature is raised to the brazing temperature of 1250℃-1400℃ at a rate of 5℃ / min-10℃ / min and held for 5min-20min.

10. The method for joining SiCf / SiC composite materials with silicon-based high-temperature solder as described in claim 8, characterized in that, The thickness of the MAX phase Pr3Si2C2 transition layer is 5μm-20μm.

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