A method for laser-induced multi-scale microtexture-assisted brazing of composite materials

Abstract

The present invention provides a method for laser-induced multi-scale micro-texturing assisted brazing of composite materials, comprising the following steps: Step 3: Using a laser in air, the surface of the fiber-reinforced ceramic matrix composite material to be welded is subjected to surface texturing treatment. During the laser texturing process, the fiber-reinforced ceramic matrix composite material is placed at the center of the laser objective stage, and then a defocus of -5 to 5 mm, a laser power of 0 to 300 W, and a laser scanning speed of 5 to 100 mm s is used. –1 The laser is then vertically irradiated to produce a textured fiber-reinforced ceramic matrix composite. Step 4: Active brazing filler metal is placed between the textured fiber-reinforced ceramic matrix composite obtained in Step 3 and the metal surface to be welded, completing the brazing assembly. This method uses surface subtraction to texture the originally flat interface reaction layer. Compared to surface additive methods, which are complex, require demanding processing conditions, and have high process costs, this method significantly reduces both the economic and labor costs of the process.

Description

Technical Field

[0001] The present invention relates to the field of fiber-reinforced ceramic-based composite materials, and in particular to a method for laser-induced multi-scale micro-texture-assisted brazing of composite material surfaces. Background Art

[0002] Fiber-reinforced ceramic matrix composites are widely used in high-end fields such as aerospace, high-speed transportation, and nuclear energy due to their excellent properties such as high temperature resistance, low density, high strength, high modulus, and high toughness. These materials usually need to be connected by vacuum brazing technology to ensure reliability and durability in extreme environments. Vacuum brazing not only provides precise dimensional control and surface quality, but also can simultaneously complete the brazing and quenching processes, improving production efficiency. It is a key technology for manufacturing high-performance composite components. However, fiber-reinforced ceramic matrix composite components are often in service under harsh working conditions such as high temperature, thermal vibration, and alternating loads, which makes the brazed joint interface prone to rapid brittle fracture failure. To this end, there is an urgent need to improve the toughness of the weld while slowly releasing the high residual stress in the joint to ensure the service reliability of the joint under working conditions.

[0003] Current research generally believes that the interfacial reaction layer between the fiber-reinforced ceramic matrix composite (FRCMC) and the braze seam in FRC-metal brazed joints is the most vulnerable location for joint fracture. To address this, researchers primarily employ two approaches to improve brazed joint performance: braze seam recombination and interface structure modification. Braze seam recombination primarily strengthens the joint by introducing a uniformly distributed, finely divided high-performance reinforcement phase into the braze seam, improving the thermophysical properties and ductility of the weld. While this approach effectively creates a gradient transition in joint properties and indirectly improves the failure threshold at the ceramic-braze interface, it does not alter the inherent tendency for dislocations to rapidly propagate within the flat interface structure during joint assembly, limiting further improvements in joint strength and toughness. In contrast, interface structure modification can roughen the originally flat interface reaction layer through surface additive or subtractive processes, thereby directly interfering with the fracture behavior of the interface between the ceramic or composite material and the braze seam. However, surface additive methods are associated with complex processes, demanding processing conditions, and high costs. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for laser-induced multi-scale micro-texture-assisted brazing of composite materials, which solves the problem that due to the strong mismatch in the thermal expansion coefficient and elastic modulus between fiber-reinforced ceramic-based composite materials and metal materials, high residual stress exists in the brazed joint, which weakens the bearing capacity of the joint. At the same time, the attitude control engine of aerospace vehicle mainly serves under harsh working conditions of high temperature, thermal vibration, and alternating load coupling, which leads to the problem of rapid brittle fracture failure at the interface of the transition ring-nozzle heterogeneous brazed joint.

[0005] In order to achieve the above-mentioned object of the invention, a method for laser-induced multi-scale micro-texture-assisted brazing of composite materials is provided, comprising the following steps:

[0006] Step 1: The fiber-reinforced ceramic matrix composite material is cut into blocks of any desired size by wire cutting, and then ultrasonically cleaned in ethanol for 10 to 15 minutes and dried in an oven;

[0007] Step 2: The clean fiber-reinforced ceramic matrix composite material to be welded obtained in step 1 is polished with 600-800 mesh silicon carbide sandpaper to remove scratches on the fiber-reinforced ceramic matrix composite material to be welded, and then ultrasonically cleaned in ethanol for 10-15 minutes, and placed in an oven at 60-80°C to dry before use;

[0008] Step 3: Use a laser to texturize the surface of the fiber-reinforced ceramic matrix composite material to be welded obtained in step 2 in air. During the laser texturing process, the fiber-reinforced ceramic matrix composite material is placed at the center of the laser objective stage, and then the defocus is -5 to 5 mm, the laser power is 0 to 300 W, and the laser scanning speed is 5 to 100 mm s. –1 The textured fiber-reinforced ceramic matrix composite material is obtained by vertical laser irradiation.

[0009] Step 4: placing an active brazing filler metal between the textured fiber-reinforced ceramic matrix composite material obtained in step 3 and the metal surface to be welded to complete the brazing assembly;

[0010] Step 5: Place the welded assembly from step 4 into a vacuum brazing furnace and evacuate the furnace until the vacuum is less than 3×10 –3 Pa, then 5~30℃min –1 The vacuum brazing furnace is heated to 30-120℃ above the melting point of the brazing material at a heating rate of 1-10℃ min. –1 The vacuum brazing furnace is cooled to room temperature at a cooling rate to complete the brazing process and obtain fiber-reinforced ceramic matrix composite materials or ceramic and metal brazing joints.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] 1. The present invention utilizes laser irradiation to create a fiber-reinforced ceramic matrix composite (FMC) with a significant precision subtractive effect. The textured FMC, with a serrated fiber array structure, modifies the interface microstructure of the parent material, thereby forming a mechanically interlocking pinning structure in the brazed joint. Simultaneously, low linear expansion coefficient particles are formed on the FMC surface, achieving brazing joint recombining, improving brazing joint performance, and alleviating joint residual stress. The alternating structure formed by the high-strength and tough FMC matrix and the excellent plasticity of the brazing filler metal solidified in the subtractive zone can fully dissipate crack propagation energy when subjected to external forces by inducing crack bridging, crack deflection, and fiber pullout, thereby improving the mechanical properties of the joint. Furthermore, the uniform, fine, high-performance reinforcement phases produced by the laser-induced surface texturing of the FMC effectively improve the thermophysical properties and plastic toughness of the weld, thereby strengthening the joint.

[0013] 2. The present invention roughens the originally flat interface reaction layer through a surface subtractive method. Compared with the surface additive method with complex process, harsh process conditions and high process cost, this method greatly reduces the economic cost and labor cost of the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A schematic diagram of the overall structure of a method for laser-induced multi-scale micro-texture-assisted brazing of composite materials provided by the present invention;

[0015] Figure 2 A schematic diagram of the partial structure of a method for laser-induced multi-scale micro-texturing assisted brazing of a composite material surface provided by the present invention. DETAILED DESCRIPTION

[0016] To make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them.

[0017] Example 1

[0018] A method for laser-induced multi-scale microtexture-assisted brazing of composite materials comprises the following steps:

[0019] 1. C f The SiC / SiC composites were obtained by wire cutting to obtain blocks of 5 mm × 5 mm × 5 mm, which were then ultrasonically cleaned in ethanol for 10 min and dried in an oven.

[0020] 2. The clean C obtained in step 1 f The surface to be welded of the / SiC composite material was polished with 800-grit silicon carbide sandpaper to remove the C f / SiC composite material to be welded, and then ultrasonically cleaned in ethanol for 10 min, and placed in an oven at 80 ° C for use;

[0021] 3. Use continuous laser to irradiate the C obtained in step 2 in air. f The surface of the welded surface of the / SiC composite material was subjected to surface texturing. During the laser texturing process, C f The / SiC composite material was placed at the center of the laser objective stage, and then the defocus was 0 mm, the laser power was 80 W, and the laser scanning speed was 50 mm s –1 The laser is irradiated vertically to obtain the textured C f / SiC composite materials;

[0022] 4. Place the Ag-27.5Cu-4.5Ti (wt.%) active solder foil on the textured C f The brazing assembly is completed between the surface to be welded of the SiC composite material and the metal Nb;

[0023] 5. Place the welded assembly in step 4 into a vacuum brazing furnace and evacuate until the vacuum degree is less than 3×10 –3 Pa, then 10℃min –1 The vacuum brazing furnace is heated to 880℃ at a heating rate and then kept warm for 10min. –1 The vacuum brazing furnace is cooled to room temperature at a cooling rate to complete the brazing process and obtain C f / SiC composite material and metal Nb brazing joint.

[0024] Example 2

[0025] The difference between this embodiment and the first embodiment is that: in step 1, C f The SiC / SiC composite material was cut into a 10 mm×10 mm×8 mm block by wire cutting, and then ultrasonically cleaned in ethanol for 15 minutes and dried in an oven. Other steps and parameters were the same as those in Example 1.

[0026] Example 3

[0027] The difference between this embodiment and Examples 1 and 2 is that: in step 2, the clean fiber-reinforced ceramic matrix composite material to be welded is polished with 800-mesh silicon carbide sandpaper to remove scratches on the fiber-reinforced ceramic matrix composite material to be welded, and then ultrasonically cleaned in ethanol for 10 minutes, and placed in a 60°C oven to dry before use. The other steps and parameters are the same as those in Specific Examples 1 and 2.

[0028] Example 4

[0029] The difference between this embodiment and Examples 1 to 3 is that: in step 2, the clean fiber-reinforced ceramic matrix composite material to be welded is polished with 600-grit silicon carbide sandpaper to remove scratches on the fiber-reinforced ceramic matrix composite material to be welded, and then ultrasonically cleaned in ethanol for 15 minutes, and placed in an 80°C oven to dry before use. The other steps and parameters are the same as Examples 1 to 3.

[0030] Example 5

[0031] The difference between this embodiment and embodiments 1 to 4 is that in step 3, the defocus distance is 0 mm, the laser power is 80 W, and the laser scanning speed is 50 mm s -1 The laser is vertically irradiated to obtain a textured fiber-reinforced ceramic matrix composite material. Other steps and parameters are the same as those in Examples 1 to 4.

[0032] Example 6

[0033] The difference between this embodiment and embodiments 1 to 5 is that: in step 3, the defocusing amount is -1 mm, the laser power is 40 W, and the laser scanning speed is 80 mm s -1 The laser is vertically irradiated to obtain a textured fiber-reinforced ceramic matrix composite material. The other steps and parameters are the same as those in Examples 1 to 5.

[0034] Example 7

[0035] The difference between this embodiment and embodiments 1 to 6 is that: in step 3, the defocus distance is 1 mm, the laser power is 120 W, and the laser scanning speed is 30 mm s -1 The other steps and parameters are the same as those in Examples 1 to 6.

[0036] Example 8

[0037] The difference between this embodiment and embodiments 1 to 7 is that the solder in step 4 is an active solder such as Ag-based, Cu-based, Ti-based, or Ni-based. The other steps and parameters are the same as those in embodiments 1 to 7.

[0038] Embodiment 9

[0039] The difference between this embodiment and embodiments 1 to 8 is that: in step 4, the fiber-reinforced ceramic matrix composite material is C f / SiC composite materials, C f / C composite materials or C f -C / SiC composite materials, etc. Other steps and parameters are the same as those in Examples 1 to 8.

[0040] Example 10

[0041] The difference between this embodiment and embodiments 1 to 9 is that the metal base material in step 3 is Nb, Ni-based high-temperature alloy, TC4 titanium alloy, TiAl alloy, etc. The other steps and parameters are the same as those of embodiments 1 to 9.

[0042] like Figure 1 As shown, Figure 1 To use low power (80W) continuous laser to C f After surface texturing treatment of the / SiC surface, the C f A multi-scale hierarchical structure appears on the surface of the SiC composite material, namely the height difference between the planar fiber area and the normal fiber area, and the height difference between the fiber and the matrix material. At the same time, only the matrix material is selectively removed and the carbon fibers are retained on its surface.

[0043] The C f The morphology of the joints brazed with Nb / SiC composites and 80W laser textured C f / SiC-Nb joints show continuous hierarchical pinning and a complete connection interface with non-flat structure. f The reaction layer interface on the / SiC side is replaced by a fiber-reinforced transition zone.

[0044] like Figure 2 As shown, compared with the direct brazing joint, the C f The room temperature shear strength of the SiC-Nb joint increased by 1 times to ~46 MPa.

[0045] The present invention utilizes laser irradiation to produce a fiber-reinforced ceramic matrix composite with a serrated fiber array structure, resulting in a precise reduction effect. This textured fiber-reinforced ceramic matrix composite material modifies the interface microstructure of the parent material, thereby forming a mechanically interlocking pinning structure in the brazed joint. Simultaneously, low linear expansion coefficient particles are formed on the surface of the fiber-reinforced ceramic matrix composite material, achieving brazing joint recombining, improving brazing joint performance, and alleviating joint residual stress. The alternating structure formed by the high-strength and tough fiber-reinforced ceramic matrix composite material matrix and the excellent plasticity of the brazing filler metal solidified in the reduction zone can fully dissipate the energy of crack propagation by inducing crack bridging, crack deflection, and fiber pullout when bearing external forces, thereby improving the mechanical properties of the joint. Furthermore, the uniform, fine, high-performance reinforcement phase produced by the laser-induced surface texturing of the fiber-reinforced ceramic matrix composite material can effectively improve the thermophysical properties and plastic toughness of the weld, thereby strengthening the joint.

[0046] The present invention roughens the originally flat interface reaction layer by using a surface subtractive method. Compared with a surface additive method with complex process, harsh process conditions and high process cost, this method greatly reduces the economic cost and labor cost of the process.

[0047] The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Although this specification has described the present invention in detail with reference to the above embodiments, the present invention is not limited to the above embodiments. Therefore, any modification or equivalent replacement of the present invention; and all technical solutions and improvements thereof that do not depart from the spirit and scope of the invention are included in the scope of the claims of the present invention.

Claims

1. A method for laser-induced multi-scale microtexture-assisted brazing of composite materials, characterized in that: The following steps are involved: Step 1: The fiber-reinforced ceramic matrix composite is cut into blocks of any desired size by wire cutting, then ultrasonically cleaned in ethanol for 10 to 15 minutes and dried in an oven; Step 2: The clean fiber-reinforced ceramic matrix composite material obtained in step 1 is polished with 600-800 mesh silicon carbide sandpaper to remove scratches on the surface of the fiber-reinforced ceramic matrix composite material to be welded, and then ultrasonically cleaned in ethanol for 5-15 minutes, and then placed in an oven at 60-80°C to dry before use; Step 3: Use a laser to texturize the surface of the fiber-reinforced ceramic matrix composite material to be welded obtained in step 2 in air. During the laser texturing process, the fiber-reinforced ceramic matrix composite material is placed at the center of the laser objective stage, and then the defocus is set to -5 ~ 5 mm, the laser power is 0 ~ 300 W, and the laser scanning speed is 5 ~ 100 mm s –1 By vertically irradiating the laser, a textured fiber-reinforced ceramic matrix composite with a fiber array zigzag structure is obtained. At the same time, low linear expansion coefficient particles are formed on the surface of the fiber-reinforced ceramic matrix composite, which realizes brazing seam compounding, improves brazing seam performance, and relieves joint residual stress. Step 4: placing an active brazing filler metal between the textured fiber-reinforced ceramic matrix composite material obtained in step 3 and the metal surface to be welded to complete the brazing assembly; Step 5: Place the welded assembly from step 4 into a vacuum brazing furnace and evacuate the furnace until the vacuum is less than 3 × 10 –3 Pa, then 5 ~ 30 ℃ min –1 The vacuum brazing furnace is heated to 30~120℃ above the melting point of the brazing material at a heating rate of 1~10℃ min. –1 The vacuum brazing furnace is cooled to room temperature at a cooling rate to complete the brazing process and obtain fiber-reinforced ceramic matrix composite materials or ceramic and metal brazing joints.

2. The method for laser-induced multi-scale micro-texture-assisted brazing of composite materials according to claim 1, characterized in that: In step 1, the fiber-reinforced ceramic matrix composite material was cut into blocks with a size of 5 mm × 5 mm × 5 mm by wire cutting, and then ultrasonically cleaned in ethanol for 10 minutes and dried in an oven for use.

3. The method for laser-induced multi-scale microtexture-assisted brazing of composite materials according to claim 2, characterized in that: During the laser texturing process in step 3, C f The SiC fiber reinforced ceramic matrix composite material was placed at the center of the laser objective stage, and then the defocus was 0 mm, the laser power was 80 W, and the laser scanning speed was 50 mm s –1 The laser is irradiated vertically to obtain the textured C f / SiC fiber reinforced ceramic matrix composites.

4. The method for laser-induced multi-scale microtexture-assisted brazing of composite materials according to claim 2, characterized in that: During the laser texturing process in step 3, C f The / SiC fiber reinforced ceramic matrix composite material was placed at the center of the laser objective stage, and then the defocus was set to –1 mm, the laser power was 40 W, and the laser scanning speed was 10 mms –1 The laser is irradiated vertically to obtain the textured C f / SiC fiber reinforced ceramic matrix composites.

5. The method for laser-induced multi-scale micro-texture-assisted brazing of composite materials according to claim 2, characterized in that: During the laser texturing process in step 3, C f The C / C fiber reinforced ceramic matrix composite material was placed at the center of the laser objective stage, and then the defocus was set to –1 mm, the laser power was 120 W, and the laser scanning speed was 80 mm s –1 The laser is irradiated vertically to obtain the textured C f / C fiber reinforced ceramic matrix composites.

6. The method for laser-induced multi-scale microtexture-assisted brazing of composite materials according to claim 2, characterized in that: During the laser texturing process in step 3, C f The C-SiC fiber reinforced ceramic matrix composite material was placed at the center of the laser objective stage, and then the defocus was 1 mm, the laser power was 160 W, and the laser scanning speed was 30 mms. –1 The laser is irradiated vertically to obtain the textured C f / C-SiC fiber reinforced ceramic matrix composites.

7. The method for laser-induced multi-scale microtexture-assisted brazing of composite materials according to claim 2, characterized in that: In step 4, the textured C was brazed with BNi2 (6.0–8.0 Cr, 4.0–5.0 Si, 2.75–3.5 B, 2.5–3.5 Fe, bal. Ni, wt%) active brazing filler metal. f / C composite material and metal GH3536, heating rate 15 ℃ min –1 The brazing temperature was 1050 °C, the holding time was 5 min, and the cooling rate was 3 °C min –1 .

8. The method for laser-induced multi-scale microtexture-assisted brazing of composite materials according to claim 2, characterized in that: In step 4, the textured C f / SiC composite material and metal Nb, heating rate 10 ℃ min –1 The brazing temperature was 880 °C, the temperature was kept at 10 min, and the cooling rate was 5 °C min –1 .

Images