A method for realizing C based on Ti-Ni-Nb composite intermediate layer f High temperature brazing method of SiC composite material and YSZ ceramic

Abstract

A Ti-Ni-Nb composite intermediate layer based on C f The invention relates to a method for high temperature brazing of a YSZ ceramic with a SiC composite material, and relates to the technical field of brazing of dissimilar materials. f / SiC composite materials are difficult to form high strength and high service temperature joints. f / SiC and YSZ ceramic joints are metallurgically bonded to achieve high-quality bonding. At a brazing temperature of 1190°C and a holding time of 20 minutes, the joint has a maximum shear strength of 59 MPa at room temperature, a maximum shear strength of 48 MPa at 500°C, and a maximum shear strength of 11 MPa at 1000°C. f The present invention provides a method for high-temperature brazing of Cf / SiC composite materials and YSZ ceramics based on a Ti-Ni-Nb composite intermediate layer.

Description

Technical Field

[0001] The present invention relates to the technical field of dissimilar materials brazing, and in particular to a method for achieving C f Method for high temperature brazing of / SiC composite materials and YSZ ceramics. Background Art

[0002] Modern aircraft engines are developing towards high thrust-to-weight ratio and high maneuverability, especially the new generation of variable cycle engines, which have reached a new height in terms of engine thrust and lift. The tail nozzle is a key component for aircraft engines to generate thrust and lift. The magnitude and direction of the thrust generated by the nozzle have a decisive influence on the performance of the aircraft engine. This requires the aircraft engine C f The adjustment of the expansion plate of the / SiC composite tail nozzle is more accurate and rapid, which is achieved through the transmission of the metal ear seat connected to it. f The expansion flaps of the SiC composite material are exposed to aerodynamic forces and high-temperature aerodynamic heat (up to 1000°C) for a long time, while the metal lugs have limited temperature resistance. Therefore, it is necessary to introduce high-temperature resistant insulation materials with low thermal conductivity to control the temperature of the metal lugs, thereby slowing down the deformation and cracking of the metal lugs.

[0003] Yttria stabilized zirconia ceramics (abbreviated as YSZ ceramics) is an advanced ceramic thermal insulation material, which is composed of zirconium oxide and stabilizer yttria. It has a high melting point, excellent insulation performance, thermal stability and toughness, and is widely used in high temperature structural materials, heat protection materials and other fields. Therefore, YSZ ceramics can be used as C in aircraft engines. f / SiC composite material expansion adjustment piece and metal ear seat insulation material. The main difficulty in the application of YSZ ceramic insulation layer is how to achieve C f It can provide a reliable connection between the YSZ ceramic thermal insulation layer and the SiC composite material, and ensure that the joint has strong high-temperature service capability.

[0004] YSZ ceramics are currently mainly connected by air reaction brazing or glass solder sintering. Air reaction brazing mainly uses Ag as the matrix and adds various oxides, but it is difficult to meet the instantaneous high temperature conditions of 1000°C. Glass solder will produce a certain degree of crystallization during the sintering process, which deteriorates the mechanical properties of the glass, resulting in weak thermal shock resistance of the joint under this process and easy cracking.

[0005] Currently, there are few reports on high-temperature vacuum brazing of YSZ ceramics. Some researchers have used TiNi metal brazing filler metal to connect YSZ ceramics to stainless steel. The melting point of the brazing filler metal can reach 942℃, but it still does not reach the service temperature of aircraft tail nozzle expansion flaps. (Indacochea J E. Polar A. Interface development in joining yttria stabilizedzirconia to stainless steel by in-situ alloying with Ni / Ti filler metals, 2007.) Therefore, a method for joining YSZ ceramics to C f High temperature brazing method of SiC composite materials is very important for obtaining C / SiC composite materials with stronger temperature resistance. f / SiC composite material expansion adjustment plate and metal ear seat joint, thereby increasing the tail nozzle outlet temperature and improving the engine thrust-to-weight ratio is of great significance. Summary of the Invention

[0006] The purpose of this invention is to solve the problem of the existing YSZ ceramics and C f It is difficult to form high strength and high service temperature connection joints between C / SiC composite materials, and a method is provided to realize C f Method for high temperature brazing of / SiC composite materials and YSZ ceramics.

[0007] A method for realizing C based on Ti-Ni-Nb composite intermediate layer f The method for high temperature brazing of SiC composite material and YSZ ceramic is carried out in the following steps:

[0008] Step S1: YSZ ceramics and C f / Pre-welding treatment of SiC composite materials;

[0009] YSZ ceramics and C f / SiC composite materials are cut, then polished and ultrasonically cleaned to obtain the processed YSZ ceramics and C f / SiC composite materials;

[0010] Step S2: pre-welding treatment of the Ti-Ni-Nb composite foil;

[0011] Ti, Ni and Nb foils are cut, polished and ultrasonically cleaned, and then bonded together in the order of Ti / Ni / Nb / Ni / Ti under vacuum conditions. Finally, pressure is applied to the bonded composite foil to obtain a TiNiNb composite foil.

[0012] Step S3: assembling the test piece to be welded;

[0013] The processed YSZ ceramics obtained in step S1 and C f / SiC composite material and the TiNiNb composite foil obtained in step S2, from bottom to top according to the YSZ ceramic / composite foil / C f / SiC composite materials are stacked in sequence to obtain an assembly;

[0014] Step S4: vacuum diffusion connection;

[0015] Apply pressure to the assembly obtained in step S3, then heat it to 900-1000°C under vacuum, continue heating it to 1160-1190°C, and keep it at 1160-1190°C for 10-60 minutes; after the end of the heat preservation, cool it to 20-200°C to complete the C-based Ti-Ni-Nb composite intermediate layer. f High temperature brazing of / SiC composite materials and YSZ ceramics.

[0016] Beneficial effects of the present invention:

[0017] (1) The present invention realizes C based on Ti-Ni-Nb composite intermediate layer f This method for high-temperature brazing of 100 mm / SiC composites and YSZ ceramics utilizes the ability of Nb to react with the TiNi eutectic at approximately 1150°C to form a pseudo-binary phase, which increases the service temperature of the joint. The introduction of Nb also reduces the brittle Ti-Ni phase. Furthermore, the (Nb, Ti) solid solution within the pseudo-binary eutectic possesses high plasticity, contributing to improved joint mechanical properties. Ultimately, this method utilizes the principles of reaction brazing to form a high-quality, high-temperature-resistant joint.

[0018] (2) The present invention can make C f / SiC and YSZ ceramic joints are metallurgically bonded to achieve high-quality bonding. Under the conditions of a brazing temperature of 1190°C and a holding time of 20 minutes, the joint has a maximum shear strength of 59 MPa at room temperature, a maximum shear strength of 48 MPa at 500°C, and a maximum shear strength of 11 MPa at 1000°C (there is currently no data available in the literature that can meet the service temperature of 1000°C). f / SiC and YSZ ceramics are connected while ensuring the high temperature resistance of the joint.

[0019] The present invention can obtain a method for realizing C based on Ti-Ni-Nb composite intermediate layer. f Method for high temperature brazing of / SiC composite materials and YSZ ceramics. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1The YSZ ceramics obtained in Example 1 and the C f SEM morphology of the joint of / SiC composite material;

[0021] Figure 2 The YSZ ceramics obtained in Example 2 and the C f SEM morphology of the joint of / SiC composite material;

[0022] Figure 3 A schematic diagram showing the brazing assembly of the base material and the solder in the present invention. DETAILED DESCRIPTION

[0023] Specific embodiment 1: This embodiment is based on a Ti-Ni-Nb composite intermediate layer to achieve C f The method for high temperature brazing of SiC composite material and YSZ ceramic is carried out as follows:

[0024] Step S1: YSZ ceramics and C f Pre-welding treatment of / SiC composite materials;

[0025] YSZ ceramics and C f / SiC composite materials are cut, then polished and ultrasonically cleaned to obtain the processed YSZ ceramics and C f / SiC composite materials;

[0026] Step S2: pre-welding treatment of the Ti-Ni-Nb composite foil;

[0027] Ti, Ni and Nb foils are cut, polished and ultrasonically cleaned, and then bonded together in the order of Ti / Ni / Nb / Ni / Ti under vacuum conditions. Finally, pressure is applied to the bonded composite foil to obtain a TiNiNb composite foil.

[0028] Step S3: assembling the test piece to be welded;

[0029] The processed YSZ ceramics obtained in step S1 and C f / SiC composite material and the TiNiNb composite foil obtained in step S2, from bottom to top according to the YSZ ceramic / composite foil / C f / SiC composite materials are stacked in sequence to obtain an assembly (such as Figure 3 shown);

[0030] Step S4: vacuum diffusion connection;

[0031] Apply pressure to the assembly obtained in step S3, then heat it to 900-1000°C under vacuum, continue heating it to 1160-1190°C, and keep it at 1160-1190°C for 10-60 minutes; after the end of the heat preservation, cool it to 20-200°C to complete the C-based Ti-Ni-Nb composite intermediate layer. f High temperature brazing of / SiC composite materials and YSZ ceramics.

[0032] Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that in step S1, YSZ ceramics and C f The surface to be welded of the SiC composite material was polished in stages using 600-mesh, 1000-mesh and 1500-mesh sandpaper.

[0033] The other steps are the same as those in the first embodiment.

[0034] Specific embodiment 3: This embodiment differs from specific embodiment 1 or 2 in that: in step S1, YSZ ceramics and C f The / SiC composite material is placed in ethanol or acetone and ultrasonically cleaned at a frequency of 70 to 150 kHz for 5 to 30 minutes.

[0035] The other steps are the same as those in the first or second embodiment.

[0036] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that: in step S2, 3000-mesh and 5000-mesh sandpaper are used to polish the upper and lower surfaces of the Ti, Ni and Nb foils step by step.

[0037] The other steps are the same as those in Specific Embodiments 1 to 3.

[0038] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that: in step S2, the Ti, Ni and Nb foils are placed in ethanol or acetone and ultrasonically cleaned at a frequency of 70 to 150 kHz for 5 to 30 minutes.

[0039] The other steps are the same as those in Specific Embodiments 1 to 4.

[0040] Specific embodiment 6: This embodiment differs from specific embodiments 1 to 5 in that in step S2 , the thickness ratio of the Ti foil to the Ni foil is 8:(5-10), and the thickness ratio of the Ni foil to the Nb foil is 6:(4-10).

[0041] The other steps are the same as those in Specific Embodiments 1 to 5.

[0042] Specific embodiment 7: This embodiment differs from specific embodiments 1 to 6 in that the pressure applied in step S2 is 5 to 10 MPa.

[0043] The other steps are the same as those in Specific Embodiments 1 to 6.

[0044] Specific embodiment eight: This embodiment differs from specific embodiments one to seven in that the pressure applied in step S4 is 0.05-0.2 MPa.

[0045] The other steps are the same as those in Specific Embodiments 1 to 7.

[0046] Specific embodiment 9: The difference between this embodiment and specific embodiments 1 to 8 is that the vacuum degree in step S4 reaches 5×10 -3 Start heating at Pa.

[0047] The other steps are the same as those in Specific Embodiments 1 to 8.

[0048] Specific embodiment ten: This embodiment differs from specific embodiments one to nine in that: in step S4, the two heating rates are 8-12°C / min and 3-6°C / min respectively, and the cooling rate is 3-6°C / min.

[0049] The other steps are the same as those in Specific Embodiments 1 to 9.

[0050] The following examples are used to verify the beneficial effects of the present invention:

[0051] Example 1: A method for realizing C based on Ti-Ni-Nb composite intermediate layer f The method for high temperature brazing of SiC composite material and YSZ ceramic is carried out in the following steps:

[0052] Step S1: YSZ ceramics and C f / Pre-welding treatment of SiC composite materials;

[0053] Cut the YSZ ceramic into 16mm×8mm×3mm by diamond cutting. For the 16mm×8mm×3mm cubic YSZ ceramic, any 16mm×8mm surface is used as the surface to be welded. f / SiC composite materials are cut into 4mm×4mm×3mm by diamond cutting method. f / SiC composite material, any 4mm×4mm surface of which is used as the surface to be welded;

[0054] YSZ ceramics and C f The surface to be welded of the YSZ / SiC composite material was polished step by step with 600-mesh, 1000-mesh and 1500-mesh sandpaper to remove surface impurities and ensure that the surface to be welded was smooth and flat. After polishing, it was placed in ethanol and ultrasonically cleaned in an ultrasonic cleaning machine at a frequency of 100kHz for 5 minutes. During the cleaning process, ethanol or acetone was replaced and the cleaning was repeated twice. After cleaning, the YSZ ceramic and Cf / SiC composite material is placed in a vacuum bag for later use;

[0055] Step S2: pre-welding treatment of the Ti-Ni-Nb composite foil;

[0056] Ti, Ni, and Nb foils were cut with scissors to obtain 7 mm × 7 mm Ti, Ni, and Nb foils. The upper and lower surfaces of the Ti, Ni, and Nb foils were then polished step by step using 3000- and 5000-grit sandpaper. After polishing, the foils were placed in ethanol and ultrasonically cleaned in an ultrasonic cleaner at a frequency of 100 kHz for 5 minutes. The cleaned foils were then placed separately in vacuum bags. The Ti, Ni, and Nb foils were bonded together in the order of Ti / Ni / Nb / Ni / Ti using a spot welder. The foils were then held between two flat surfaces and a pressure of 5 MPa was applied to obtain a TiNiNb composite foil, which was flattened and sealed in a bag for later use.

[0057] The thickness ratio of Ti foil to Ni foil is 8:5, and the thickness ratio of Ni foil to Nb foil is 6:5;

[0058] Step S3: assembling the test piece to be welded;

[0059] YSZ ceramics, TiNiNb composite foil and C f / SiC composite material from bottom to top according to 16mm×8mm×3mmYSZ ceramic (to be welded facing up) / TiNiNb composite foil / 4mm×4mm×3mm C f / SiC composite materials (with the surface to be welded facing downward) are stacked in sequence to obtain an assembly;

[0060] Step S4: vacuum diffusion connection;

[0061] The assembled parts were placed in the furnace, and a pressure of 0.1 MPa was applied along the axial direction of the welded surface by the indenter to ensure close contact between the base material and the TiNiNb composite foil. The vacuum was then applied to a temperature of 5 × 10 -3 Heating was started at 1000°C at a rate of 10°C / min, and then continued to be heated to 1180°C at a rate of 5°C / min, and kept at 1180°C for 20 minutes; after the insulation was completed, it was cooled to 200°C at a rate of 5°C / min, the specimen was taken out, and the connection joint was obtained.

[0062] The shear test was carried out using an electronic universal testing machine with a loading speed of 0.5 mm / min. In this embodiment, composite foil was used as the solder to connect the YSZ ceramic and C f / SiC composite material, the resulting connection joint has a shear strength of 33MPa at room temperature and a shear strength of 30MPa at 500℃.

[0063] Example 2: A method for realizing C based on Ti-Ni-Nb composite intermediate layer f The method for high temperature brazing of SiC composite material and YSZ ceramic is carried out in the following steps:

[0064] Step S1: YSZ ceramics and C f / Pre-welding treatment of SiC composite materials;

[0065] Cut the YSZ ceramic into 16mm×8mm×3mm by diamond cutting. For the 16mm×8mm×3mm cubic YSZ ceramic, any 16mm×8mm surface is used as the surface to be welded. f / SiC composite materials are cut into 4mm×4mm×3mm by diamond cutting method. f / SiC composite material, any 4mm×4mm surface of which is used as the surface to be welded;

[0066] YSZ ceramics and C f The surface to be welded of the YSZ / SiC composite material was polished step by step with 600-mesh, 1000-mesh and 1500-mesh sandpaper to remove surface impurities and ensure that the surface to be welded was smooth and flat. After polishing, it was placed in ethanol and ultrasonically cleaned in an ultrasonic cleaning machine at a frequency of 100kHz for 5 minutes. During the cleaning process, ethanol or acetone was replaced and the cleaning was repeated twice. After cleaning, the YSZ ceramic and C f / SiC composite material is placed in a vacuum bag for later use;

[0067] Step S2: pre-welding treatment of the Ti-Ni-Nb composite foil;

[0068] Ti, Ni, and Nb foils were cut with scissors to obtain 7 mm × 7 mm Ti, Ni, and Nb foils. The upper and lower surfaces of the Ti, Ni, and Nb foils were then polished step by step using 3000- and 5000-grit sandpaper. After polishing, the foils were placed in ethanol and ultrasonically cleaned in an ultrasonic cleaner at a frequency of 100 kHz for 5 minutes. The cleaned foils were then placed separately in vacuum bags. The Ti, Ni, and Nb foils were bonded together in the order of Ti / Ni / Nb / Ni / Ti using a spot welder. The foils were then held between two flat surfaces and a pressure of 5 MPa was applied to obtain a TiNiNb composite foil, which was flattened and sealed in a bag for later use.

[0069] The thickness ratio of Ti foil to Ni foil is 8:5, and the thickness ratio of Ni foil to Nb foil is 6:5;

[0070] Step S3: assembling the test piece to be welded;

[0071] YSZ ceramics, TiNiNb composite foil and C f / SiC composite material from bottom to top according to 16mm×8mm×3mmYSZ ceramic (to be welded facing up) / TiNiNb composite foil / 4mm×4mm×3mm C f / SiC composite materials (with the surface to be welded facing downward) are stacked in sequence to obtain an assembly;

[0072] Step S4: vacuum diffusion connection;

[0073] The assembled parts were placed in the furnace, and a pressure of 0.1 MPa was applied along the axial direction of the welded surface by the indenter to ensure close contact between the base material and the TiNiNb composite foil. The vacuum was then applied to a temperature of 5 × 10 -3 Heating was started at 1000°C at a rate of 10°C / min, and then continued to be heated to 1190°C at a rate of 5°C / min, and kept at 1190°C for 20 minutes; after the insulation was completed, it was cooled to 200°C at a rate of 5°C / min, the specimen was taken out, and a connection joint was obtained.

[0074] The shear test was carried out using an electronic universal testing machine with a loading speed of 0.5 mm / min. In this embodiment, composite foil was used as the solder to connect the YSZ ceramic and C f / SiC composite material, the resulting connection joint has a shear strength of 46MPa at room temperature, 42MPa at 500℃, and 11MPa at 1000℃.

[0075] In high-temperature brazing of YSZ ceramics, the weld formed by BNi4+Ti metal brazing filler metal (Induction brazing for gassealing of anode-supported tubular solid oxide fuel cells using the nickel-based brazing alloy modified by TiH2, 2011) has large cracks on the YSZ ceramic side, and its joint strength is less than 20 MPa. In the present invention, the addition of Nb element to the TiNi metal brazing filler metal not only improves the brittleness of the TiNi brazing filler metal but also significantly improves the high-temperature resistance of the joint.

[0076] The C used in Examples 1 and 2 f / SiC composite material is a three-dimensional four-directional continuous carbon fiber reinforced silicon carbide ceramic matrix composite material. The material is prepared by the precursor infusion pyrolysis (PIP) method. The density of the material is about 1.54~1.96g / cm 3 The SiC ceramic matrix in the composite material is mainly β-SiC, and the theoretical porosity is 16%.

[0077] Figure 1The YSZ ceramics obtained in Example 1 and the C f SEM morphology of the joint of / SiC composite material, Figure 2 The YSZ ceramics obtained in Example 2 and the C f SEM morphology of the joint of / SiC composite material.

[0078] like Figure 1 As shown in Figure 2, within the brazing temperature range of 1180-1190°C, when the brazing parameters are temperature 1180°C and holding time 20 min, the solid solution and eutectic phase are evenly distributed, and the Nb intermediate layer is not completely dissolved; Figure 2 As shown in the figure, when the temperature is further increased to 1190℃, it can be found that the Nb intermediate layer is completely dissolved, the microstructure is evenly distributed, the parent material side reacts fully, and the strength is significantly improved. This proves that the moderate increase in brazing temperature can improve the solubility of the Nb intermediate layer and finally the YSZ ceramics and C f The shear strength of the / SiC composite material connection joint is significantly improved.

Claims

1. A method for realizing C based on Ti-Ni-Nb composite intermediate layer f A method for high-temperature brazing of SiC composite materials and YSZ ceramics, characterized in that The method proceeds as follows: Step S1: YSZ ceramics and C f / Pre-welding treatment of SiC composite materials; YSZ ceramics and C f / SiC composite materials are cut, then polished and ultrasonically cleaned to obtain the processed YSZ ceramics and C f / SiC composite materials; Step S2: pre-welding treatment of the Ti-Ni-Nb composite foil; Ti, Ni and Nb foils are cut, polished and ultrasonically cleaned, and then bonded together in the order of Ti / Ni / Nb / Ni / Ti under vacuum conditions. Finally, pressure is applied to the bonded composite foil to obtain a TiNiNb composite foil. Step S3: assembling the test piece to be welded; The processed YSZ ceramics obtained in step S1 and C f / SiC composite material and the TiNiNb composite foil obtained in step S2, from bottom to top according to the YSZ ceramic / composite foil / C f / SiC composite materials are stacked in sequence to obtain an assembly; Step S4: vacuum diffusion connection; Apply pressure to the assembly obtained in step S3, then heat it to 900-1000°C under vacuum, continue heating it to 1160-1190°C, and keep it at 1160-1190°C for 10-60 minutes; after the end of the heat preservation, cool it to 20-200°C to complete the C-based Ti-Ni-Nb composite intermediate layer. f High temperature brazing of / SiC composite materials and YSZ ceramics.

2. The method according to claim 1 to realize C based on Ti-Ni-Nb composite intermediate layer f A method for high-temperature brazing of SiC composite materials and YSZ ceramics, characterized in that In step S1, YSZ ceramics and C f The surface to be welded of the SiC composite material was polished in stages using 600-mesh, 1000-mesh and 1500-mesh sandpaper.

3. The method according to claim 1 to realize C based on Ti-Ni-Nb composite intermediate layer f A method for high-temperature brazing of SiC composite materials and YSZ ceramics, characterized in that In step S1, YSZ ceramics and C f The / SiC composite material is placed in ethanol or acetone and ultrasonically cleaned at a frequency of 70 to 150 kHz for 5 to 30 minutes.

4. The method according to claim 1 to realize C based on Ti-Ni-Nb composite intermediate layer f A method for high-temperature brazing of SiC composite materials and YSZ ceramics, characterized in that In step S2, 3000-grit and 5000-grit sandpapers are used to polish the upper and lower surfaces of the Ti, Ni, and Nb foils in stages.

5. The method according to claim 1 to realize C based on Ti-Ni-Nb composite intermediate layer f A method for high-temperature brazing of SiC composite materials and YSZ ceramics, characterized in that In step S2, the Ti, Ni and Nb foils are placed in ethanol or acetone and ultrasonically cleaned at a frequency of 70 to 150 kHz for 5 to 30 minutes.

6. A method for realizing C based on a Ti-Ni-Nb composite intermediate layer according to claim 1, 4 or 5. f A method for high-temperature brazing of SiC composite materials and YSZ ceramics, characterized in that In step S2 , the thickness ratio of the Ti foil to the Ni foil is 8:(5-10), and the thickness ratio of the Ni foil to the Nb foil is 6:(4-10).

7. The method according to claim 1 to realize C based on Ti-Ni-Nb composite intermediate layer f A method for high-temperature brazing of SiC composite materials and YSZ ceramics, characterized in that The pressure applied in step S2 is 5 to 10 MPa.

8. The method according to claim 1 to realize C based on Ti-Ni-Nb composite intermediate layer f A method for high-temperature brazing of SiC composite materials and YSZ ceramics, characterized in that The pressure applied in step S4 is 0.05 to 0.2 MPa.

9. The method according to claim 1 to realize C based on Ti-Ni-Nb composite intermediate layer f A method for high-temperature brazing of SiC composite materials and YSZ ceramics, characterized in that In step S4, the vacuum degree reaches 5×10 -3 Start heating at Pa.

10. The method according to claim 1 to realize C based on Ti-Ni-Nb composite intermediate layer f A method for high-temperature brazing of SiC composite materials and YSZ ceramics, characterized in that In step S4, the heating rates are 8-12°C / min and 3-6°C / min respectively, and the cooling rate is 3-6°C / min.

Images