CN103341675A - A kind of method utilizing Ti-Co-Nb solder to braze Cf/SiC composite material and metal Nb - Google Patents

Abstract

The invention discloses a method for braze welding of a Cf/SiC composite material and a metal Nb by using a Ti-Co-Nb brazing filler metal. The braze welding method disclosed by the invention is mainly used for solving the current problems that a connecting brazing filler metal for the Cf/SiC composite material and the metal Nb as well as a welding joint obtained by a braze welding connection method are poor in room temperature mechanical properties and can not resist high temperature. The method comprises the steps of: 1, burnishing; 2, cleaning; 3, assembling; and 4, braze welding. The joint obtained through braze welding according to the method has better high-temperature resistance, and the element Nb is added into the brazing filler metal to inhibit the diffusion of a base metal Nb towards the middle layer of the brazing filler metal, so that a better connection is formed. The method disclosed by the invention is used for braze welding of the Cf/SiC composite material and the metal Nb.

Description

A kind of method utilizing Ti-Co-Nb solder to braze Cf/SiC composite material and metal Nb

technical field

The present invention relates to brazing methods.

Background technique

C _f /SiC composite material is a high-temperature resistant, low-density ceramic-based thermal structural composite material, which can meet the requirements of long life below 1650°C, limited life below 2000°C, and instantaneous life below 2800°C. It has excellent properties such as thermal shock resistance, high wear resistance and hardness, chemical corrosion resistance, high thermal conductivity, and low thermal expansion coefficient. C _f /SiC composites absorb energy through mechanisms such as crack deflection, fiber breakage, and fiber pull-out during the fracture process, which enhances the strength and toughness of the material. It is considered to be a high-temperature structural ceramic with great potential in the fields of aerospace and energy. Material. Due to the limitations of its preparation and shaping methods, it is difficult to directly apply it to the above fields. Metal niobium is a high-temperature metal with good oxidation resistance, stable physical and chemical properties, metal shaping and toughness, and easy cutting. These excellent properties make it one of the important candidate materials for high-temperature structural parts in the aviation, aerospace and nuclear industries, and can be used to manufacture key components of rocket engines, spacecraft and nuclear reactors. If the connection between C _f /SiC and metal Nb is realized, the disadvantages such as difficulty in forming and processing can be overcome, and the respective advantages of the two materials can also be brought into play, and its application range will be wider. Therefore, it is of great engineering significance to achieve a reliable connection between C _f /SiC composites and metallic niobium.

At present, the active brazing method has become the preferred method for joining ceramics and metals due to its simple operation process and wide adaptability of joint size and shape. However, there are few reports on the brazing connection of C _f /SiC composite materials, mainly because the chemical activity of the composite material is low, and the conventional solder is difficult to wet its surface. However, the commonly used Ag-Cu-Ti active solder cannot meet the requirements of high-temperature use due to its low melting point.

Contents of the invention

The present invention solves the problems of poor room temperature mechanical properties and low temperature resistance of the welded joints obtained by the existing C _f /SiC composite material and metal Nb connection solder and brazing connection method, and provides a method using Ti-Co - A method for brazing _Cf /SiC composites and metal Nb with Nb solder.

A method for brazing _Cf /SiC composite material and metal Nb utilizing Ti-Co-Nb filler metal, specifically carried out according to the following steps:

1. Polish the surface to be welded of the C _f /SiC composite material with 200#, 400#, 600# and 800# metallographic sandpaper in sequence, and polish the metal Nb to the surface with 400#, 600# and 1000# metallographic sandpaper in sequence bright;

2. Immerse the polished C _f /SiC composite material and metal Nb in acetone, ultrasonically clean it for 15 minutes, then rinse it with absolute ethanol, and dry it;

3. Polish the Ti-Co-Nb solder with 400#, 600# and 1000# metallographic sandpaper in turn until the surface is bright, then immerse it in acetone, ultrasonically clean it for 10 minutes, then rinse it with absolute ethanol, dry it, and then Use 502 glue to stick the Ti-Co-Nb solder between the _Cf /SiC composite material and metal Nb after the second step, and assemble it into a _Cf /SiC composite material/Ti-Co-Nb solder/metal Nb Structure;

4. Put the structural parts obtained in step 3 into a vacuum brazing furnace, press it tightly, then evacuate to a vacuum degree of 1.0×10 ^-3 Pa, heat up to a temperature of 300°C, and hold for 8 minutes to 20 minutes; then heat up up to the brazing temperature, and perform brazing connection; then lower the temperature to 300° C., and then cool with the furnace to complete the method of brazing C _f /SiC composite material and metal Nb with Ti-Co-Nb brazing filler metal.

The beneficial effect of the invention is that in high-temperature solders, compared with expensive Au-based and Pd-based solders, Ti-based, Ni-based and Co-based solders have more practical value. Ti is one of the most basic active elements in the active solder. In order to ensure the wettability of the high-temperature solder, the present invention uses Ti-Co solder as the base, and the atomic ratio of the two is 1:1. As a high-temperature solder, Ti-50Co (at%) has a higher melting point, and the joint obtained by brazing has better high-temperature resistance. On the other hand, it can be seen from the binary phase diagram of Ti-Nb that Ti and Nb are completely solidified. Since the base metal Nb is easily eroded by the brazing filler metal at high temperature, Nb element is added to the brazing filler metal to inhibit the transfer of the base metal Nb to the brazing filler metal. The diffusion of the middle layer of the material, thus forming a better connection.

The invention is used for brazing C _f /SiC composite material and metal Nb.

Description of drawings

Figure 1 is the electronic backscattered photograph of the joint in Example 1 with a brazing temperature of 1320°C, a brazing connection time of 10 minutes, and a solder composition of Ti42.5Co42.5Nb15 (at%); Figure 2 is a scanning electron microscope image of the fracture.

Detailed ways

The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

Specific embodiment one: In this embodiment, a method for brazing _Cf /SiC composite materials and metal Nb using Ti-Co-Nb solder is specifically carried out according to the following steps:

1. Polish the surface to be welded of the C _f /SiC composite material with 200#, 400#, 600# and 800# metallographic sandpaper in sequence, and polish the metal Nb to the surface with 400#, 600# and 1000# metallographic sandpaper in sequence bright;

2. Immerse the polished C _f /SiC composite material and metal Nb in acetone, ultrasonically clean it for 15 minutes, then rinse it with absolute ethanol, and dry it;

3. Polish the Ti-Co-Nb solder with 400#, 600# and 1000# metallographic sandpaper in turn until the surface is bright, then immerse it in acetone, ultrasonically clean it for 10 minutes, then rinse it with absolute ethanol, dry it, and then Use 502 glue to stick the Ti-Co-Nb solder between the _Cf /SiC composite material and metal Nb after the second step, and assemble it into a _Cf /SiC composite material/Ti-Co-Nb solder/metal Nb Structure;

4. Put the structural parts obtained in step 3 into a vacuum brazing furnace, press it tightly, then evacuate to a vacuum degree of 1.0×10 ^-3 Pa, heat up to a temperature of 300°C, and hold for 8 minutes to 20 minutes; then heat up up to the brazing temperature, and perform brazing connection; then lower the temperature to 300° C., and then cool with the furnace to complete the method of brazing C _f /SiC composite material and metal Nb with Ti-Co-Nb brazing filler metal.

Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that the preparation method of Ti-Co-Nb solder in step 3 is specifically carried out according to the following steps: a. Place the blocks and Nb blocks in the crucible in sequence; b. Vacuum the crucible to 10 ^-1 Pa, then feed high-purity argon, and then evacuate to 10 ^-1 Pa; c. Repeat step b twice; d. Each metal block is smelted 4 to 8 times by electric arc, then cut into thin slices by electric discharge wire cutting method, and then polished and smoothed with 200#, 400#, 600# and 800# sandpaper in turn to complete Ti-Co-Nb Preparation of solder. Others are the same as in the first embodiment.

Specific embodiment three: the difference between this embodiment and specific embodiment one is: in step three, the Ti-Co-Nb solder is composed of 8.5-45 parts of niobium, 33-50 parts of cobalt and 22-22 parts by mass. Made of 41.5 parts titanium. Others are the same as in the first embodiment.

Embodiment 4: This embodiment is different from Embodiment 1 in that: the holding time in step 4 is 10 minutes. Others are the same as in the first embodiment.

Embodiment 5: The difference between this embodiment and Embodiment 1 is that the process parameters of the brazing connection in step 4 are: the brazing temperature is 1300°C-1340°C, the brazing connection time is 10min-20min, and the brazing connection time is 10min-20min. The pressure is 10 ⁴ Pa. Others are the same as in the first embodiment.

Embodiment 6: This embodiment is different from Embodiment 1 in that: when the temperature is raised to 300° C. in step 4, the heating rate is controlled to be 10° C./min. Others are the same as in the first embodiment.

Embodiment 7: This embodiment is different from Embodiment 1 in that: when the temperature is raised to the brazing temperature in step 4, the heating rate is controlled to be 5° C./min. Others are the same as in the first embodiment.

Embodiment 8: This embodiment is different from Embodiment 1 in that: when the temperature is lowered to 300° C. in step 4, the cooling rate is controlled to be 5° C./min. Others are the same as in the first embodiment.

Adopt the following examples to verify the beneficial effects of the present invention:

Embodiment one:

In this embodiment, a method for brazing _Cf /SiC composite material and metal Nb using Ti-Co-Nb solder is specifically carried out according to the following steps:

1. Polish the surface to be welded of the C _f /SiC composite material with 200#, 400#, 600# and 800# metallographic sandpaper in sequence, and polish the metal Nb to the surface with 400#, 600# and 1000# metallographic sandpaper in sequence bright;

2. Immerse the polished C _f /SiC composite material and metal Nb in acetone, ultrasonically clean it for 15 minutes, then rinse it with absolute ethanol, and dry it;

3. Polish the Ti-Co-Nb solder with 400#, 600# and 1000# metallographic sandpaper in turn until the surface is bright, then immerse it in acetone, ultrasonically clean it for 10 minutes, then rinse it with absolute ethanol, dry it, and then Use 502 glue to stick the Ti-Co-Nb solder between the _Cf /SiC composite material and metal Nb after the second step, and assemble it into a _Cf /SiC composite material/Ti-Co-Nb solder/metal Nb Structure;

4. Put the structural parts obtained in step 3 into a vacuum brazing furnace, press it tightly, then evacuate to a vacuum degree of 1.0×10 ^-3 Pa, heat up to 300°C, and hold for 10 minutes; then heat up to brazing The brazing temperature is used for brazing connection; then the temperature is lowered to 300° C., and then cooled with the furnace to complete the method of brazing C _f /SiC composite material and metal Nb with Ti-Co-Nb brazing filler metal.

The composition of Ti-Co-Nb solder in the present embodiment, brazing temperature, the mechanical test result of brazing connection time and brazing joint are shown in the table below:

In this example, the brazing temperature is 1320°C, the brazing connection time is 10 minutes, and the electronic backscattered photo of the joint with the brazing filler metal composition Ti42.5Co42.5Nb15 (at%) is shown in Figure 1, and the scanning electron microscope picture of the fracture is shown in Figure 1. 2.

The experimental results show that the Ti-Co-Nb filler metal of the present invention is used to successfully connect the _Cf /SiC composite material and the metal Nb. When kept at a brazing temperature of 1300 ° C for 20 minutes, the solder composition is Ti42. 5Co42.5Nb15(at.%), the highest connection strength of 192MPa is obtained, and under the brazing condition of 1320℃ for 10min: when the brazing material is Ti42.5Co42.5Nb15, the joint room temperature and 600℃ shear strength are respectively are 187MPa and 221.8MPa; when the solder composition is Ti35Co35Nb30, the shear strength of the joint at room temperature and 600°C are 161.4MPa and 170.7MPa respectively, and the shear strength at 600°C is higher than that at room temperature; After brazing with this type of solder, do a compression shear test at 800°C. The base metal Nb yields first and then the joint breaks. It can be seen that the shear strength of the joint is greater than the yield strength of the base metal Nb (the yield strength at 800°C is about 100MPa) .

Claims (8)

1. A method utilizing Ti-Co-Nb solder brazing _Cf /SiC composite material and metal Nb, characterized in that a kind of method utilizing Ti-Co-Nb solder brazing _Cf /SiC composite material and metal Nb method, specifically in accordance with the following steps: 1. Polish the surface to be welded of the C _f /SiC composite material with 200#, 400#, 600# and 800# metallographic sandpaper in sequence, and polish the metal Nb to the surface with 400#, 600# and 1000# metallographic sandpaper in sequence bright; 2. Immerse the polished C _f /SiC composite material and metal Nb in acetone, ultrasonically clean it for 15 minutes, then rinse it with absolute ethanol, and dry it; 3. Polish the Ti-Co-Nb solder with 400#, 600# and 1000# metallographic sandpaper in turn until the surface is bright, then immerse it in acetone, ultrasonically clean it for 10 minutes, then rinse it with absolute ethanol, dry it, and then Use 502 glue to stick the Ti-Co-Nb solder between the _Cf /SiC composite material and metal Nb after the second step, and assemble it into a _Cf /SiC composite material/Ti-Co-Nb solder/metal Nb Structure; 4. Put the structural parts obtained in step 3 into a vacuum brazing furnace, press it tightly, then evacuate to a vacuum degree of 1.0×10 ^-3 Pa, heat up to a temperature of 300°C, and hold for 8 minutes to 20 minutes; then heat up up to the brazing temperature, and perform brazing connection; then lower the temperature to 300° C., and then cool with the furnace to complete the method of brazing C _f /SiC composite material and metal Nb with Ti-Co-Nb brazing filler metal. 2. a kind of method utilizing Ti-Co-Nb solder brazing _Cf /SiC composite material and metal Nb according to claim 1 is characterized in that the preparation method of Ti-Co-Nb solder in step 3 is specific It is carried out according to the following steps: a. Put Co block, Ti block and Nb block in the crucible in order from top to bottom; b. Vacuum the crucible to 10 ^-1 Pa, then pass high-purity argon gas into it, and then Vacuumize to 10 ^-1 Pa; c. Repeat step b twice; d. Melt each metal block with electric arc for 4 to 8 times, then cut into thin slices with 200#, 400# #, 600# and 800# sandpapers were polished in sequence to make Ti-Co-Nb solder preparation complete. 3. a kind of method utilizing Ti-Co-Nb solder brazing C _f /SiC composite material and metal Nb according to claim 1, is characterized in that in step 3, Ti-Co-Nb solder is according to mass fraction It is made of 8.5-45 parts of niobium, 33-50 parts of cobalt and 22-41.5 parts of titanium. 4. A method for brazing C _f /SiC composite material and metal Nb by using Ti-Co-Nb solder according to claim 1, characterized in that the holding time in step 4 is 10 min. 5. a kind of method utilizing Ti-Co-Nb solder brazing _Cf /SiC composite material and metal Nb according to claim 1 is characterized in that the process parameter of brazing connection in the step 4 is: brazing temperature The temperature is 1300℃～1340℃, the brazing connection time is 10min～20min, and the brazing connection pressure is 10 ⁴ Pa. 6. A method of utilizing Ti-Co-Nb solder to braze _Cf /SiC composite material and metal Nb according to claim 1, characterized in that when the temperature is raised to 300° C. in step 4, the temperature rise rate is controlled 10°C/min. 7. a kind of method utilizing Ti-Co-Nb brazing filler metal brazing _Cf /SiC composite material and metal Nb according to claim 1, it is characterized in that when being warmed up to brazing temperature in step 4, control heating rate is 5°C/min. 8. A method of utilizing Ti-Co-Nb solder to braze _Cf /SiC composite materials and metal Nb according to claim 1, characterized in that when the temperature is lowered to 300°C in step 4, the cooling rate is controlled to be 5 °C/min.

Images