Nickel-based ceramic and metal connecting method and connecting piece obtained through nickel-based ceramic and metal connecting method

Abstract

The invention belongs to the technical field of welding, and provides a nickel-based ceramic and metal connecting method and a connecting piece obtained through the nickel-based ceramic and metal connecting method. The connecting method comprises the following steps that a connecting layer is arranged between nickel-based ceramic and metal, the portion between the connecting layer and the nickel-based ceramic and the portion between the connecting layer and the metal are coated with a binding agent, then vacuum brazing is conducted, and a connecting piece of the nickel-based ceramic and the metal is obtained; the connecting layer is alloy foil, and the alloy foil comprises silver, copper, titanium and molybdenum; the nickel-based ceramic comprises boron carbide powder, titanium powder, graphite powder and nickel powder; the melting point of the metal does not exceed 2000 DEG C. According to the connecting layer, residual thermal stress caused by different thermal expansion coefficients between ceramic and metal can be relieved, interface reaction can be controlled, and the joint quality can be improved. A joint of the nickel-based ceramic and metal connecting piece is uniform and compact, and no hole or microcrack is generated; connection efficiency and connection precision are high, and material deformation is small; and the connecting joint is high in strength, high in corrosion resistance and good in conductivity.

Description

Technical Field

[0001] The invention relates to the technical field of welding, and in particular to a method for connecting nickel-based ceramics and metals and a connecting piece obtained therefrom. Background Art

[0002] Metal materials, especially some high-temperature alloys such as titanium alloys and nickel-based alloys, have excellent electrical conductivity, thermal conductivity, plasticity, toughness and high specific strength, and are easy to cut, but they also have disadvantages such as poor wear resistance and poor high-temperature oxidation resistance, which reduce their service life and limit their application. Ceramic materials have good wear resistance, corrosion resistance, high elastic modulus, high-temperature mechanical properties, etc., but they are relatively brittle, sensitive to stress, and difficult to process, which greatly limits the use of ceramic materials.

[0003] Through connection technology, the good process performance and toughness of metal materials can be effectively combined with the good wear resistance and corrosion resistance of ceramic materials, giving full play to the comprehensive advantages of ceramic materials and metal materials to obtain composite materials with the advantages of both. The connection methods of ceramic and metal materials include adhesive connection, mechanical connection, diffusion connection, ultrasonic connection, plasma spray connection, physical and chemical vapor deposition connection and brazing. Brazing has the advantages of low requirements for connection surface processing accuracy, welding under low or no pressure, wide adaptability of joint shape and size, and a wide range of applications.

[0004] At present, the connection between nickel-based boron carbide ceramics and metals in the prior art still has problems such as high stress, violent reaction between ceramics and metals, and residual stress caused by mismatched thermal expansion coefficients, which affect the joint strength. Therefore, it is of great significance to obtain a method for connecting nickel-based ceramics and metals that improves joint strength and reduces residual stress. Summary of the invention

[0005] The purpose of the present invention is to provide a method for connecting nickel-based ceramics and metals and a connecting piece obtained therefrom in view of the deficiencies in the prior art.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for connecting nickel-based ceramics and metals, comprising the following steps:

[0008] The connecting layer is placed between the nickel-based ceramic and the metal, and an adhesive is applied between the connecting layer and the nickel-based ceramic and between the connecting layer and the metal, and then vacuum brazing is performed to obtain a connecting piece of the nickel-based ceramic and the metal;

[0009] The connecting layer is an alloy foil, which contains silver, copper, titanium and molybdenum; the nickel-based ceramic contains boron carbide powder, titanium powder, graphite powder and nickel powder; and the melting point of the metal does not exceed 2000°C.

[0010] Preferably, in the alloy foil, the mass ratio of silver, copper, titanium and molybdenum is 55-60:25-30:2-4:1-3;

[0011] In the nickel-based ceramic, the mass ratio of boron carbide powder, titanium powder, graphite powder and nickel powder is 1:0.5-1:1-2:0.3-0.6.

[0012] Preferably, the metal is titanium, nickel or iron.

[0013] Preferably, the thickness of the connecting layer is 20-80 μm.

[0014] Preferably, the vacuum brazing is performed sequentially at 400-450°C for the first vacuum brazing and at 960-1050°C for the second vacuum brazing;

[0015] The heating rate of vacuum brazing is 8-15℃ / min.

[0016] Preferably, the first vacuum brazing time is 3 to 7 minutes, and the second vacuum brazing time is 5 to 10 minutes.

[0017] Preferably, the temperature is lowered to 350-400° C. after vacuum brazing, and then cooled to room temperature along with the furnace to obtain a connection part between nickel-based ceramic and metal;

[0018] The rate of cooling to 350-400°C is 5-10°C / min.

[0019] As a preferred method, during vacuum brazing, the vacuum degree is 10 -2 ~10 -3 Pa.

[0020] The invention also provides a connecting piece of nickel-based ceramic and metal obtained by the method for connecting nickel-based ceramic and metal.

[0021] The beneficial effects of the present invention include the following:

[0022] 1) In nickel-based ceramics, the addition of nickel powder can increase the toughness of the ceramic layer, and graphite can reduce the friction coefficient of the ceramic layer; during vacuum brazing, the B atoms in the ceramic layer are easily diffused into the connection layer due to their small relative atomic mass, and form TiB2 with Ti, which serves as a reinforcing phase to improve the strength of the connection layer. Silver has a low melting point and is easy to form amorphous compounds with Ti and metals, making the composition uniform and forming a strong connection joint; Mo powder has the effect of particle reinforcement. Due to the low thermal expansion coefficient of Mo, it can reduce the difference in thermal expansion coefficient between nickel-based ceramics and metals, reduce residual thermal stress, and effectively improve the strength of the joint.

[0023] 2) The connection layer can relieve the residual thermal stress caused by the different thermal expansion coefficients between ceramic and metal, control the interface reaction, and improve the joint quality. The connection of the nickel-based ceramic and metal connector of the present invention is uniform and dense, without holes and microcracks; the connection efficiency and connection accuracy are high, and the material deformation is small; the connection joint has high strength, strong corrosion resistance, and good electrical conductivity. DETAILED DESCRIPTION

[0024] The present invention provides a method for connecting nickel-based ceramics and metals, comprising the following steps:

[0025] The connecting layer is placed between the nickel-based ceramic and the metal, and an adhesive is applied between the connecting layer and the nickel-based ceramic and between the connecting layer and the metal, and then vacuum brazing is performed to obtain a connecting piece of the nickel-based ceramic and the metal;

[0026] The connecting layer is an alloy foil, which contains silver, copper, titanium and molybdenum; the nickel-based ceramic contains boron carbide powder, titanium powder, graphite powder and nickel powder; and the melting point of the metal does not exceed 2000°C.

[0027] In the alloy foil of the present invention, the mass ratio of silver, copper, titanium and molybdenum is preferably 55-60:25-30:2-4:1-3, more preferably 56-59:26-29:2.5-3.5:1.5-2.5, and more preferably 57-58:27-28:3:2;

[0028] In the nickel-based ceramic, the mass ratio of boron carbide powder, titanium powder, graphite powder and nickel powder is preferably 1:0.5-1:1-2:0.3-0.6, more preferably 1:0.6-0.9:1.2-1.8:0.4-0.5, and more preferably 1:0.7-0.8:1.4-1.5:0.45.

[0029] In the present invention, the metal is preferably titanium, nickel or iron.

[0030] In the present invention, the particle size of boron carbide powder, titanium powder, graphite powder and nickel powder is preferably 50-100 μm, more preferably 60-90 μm, more preferably 70-80 μm; the purity is preferably ≥99.5%, more preferably ≥99.7%, more preferably 99.9%.

[0031] In the present invention, active elements such as titanium in metal and nickel-based ceramics can appropriately supplement the active elements required in the brazing process, thereby reducing the amount of active elements added to the connecting layer, avoiding the brittleness of the joint due to the presence of more active elements in the connecting layer, and ensuring that the connecting layer releases or buffers thermal stress.

[0032] The reaction of titanium and boron carbide can form a dense TiC reaction layer on the surface. Due to the existence of the dense TiC reaction layer, excessive reaction between nickel-based ceramics and metals and between the connecting layer and ceramics is avoided; copper, titanium and nickel form a solid solution, which has good stress relief ability and avoids the problem of too low melting point caused by the copper base.

[0033] In the present invention, the thickness of the connection layer is preferably 20 to 80 μm, more preferably 40 to 70 μm, and even more preferably 50 to 60 μm.

[0034] In the present invention, the vacuum brazing is preferably carried out at 400-450°C for the first vacuum brazing and at 960-1050°C for the second vacuum brazing, more preferably at 410-440°C for the first vacuum brazing and at 980-1020°C for the second vacuum brazing, more preferably at 420-430°C for the first vacuum brazing and at 990-1000°C for the second vacuum brazing; the heating rate of vacuum brazing is preferably 8-15°C / min, more preferably 10-13°C / min, more preferably 11-12°C / min.

[0035] In the present invention, the first vacuum brazing time is preferably 3 to 7 minutes, more preferably 4 to 6 minutes, and more preferably 5 minutes; the second vacuum brazing time is preferably 5 to 10 minutes, more preferably 6 to 9 minutes, and more preferably 7 to 8 minutes.

[0036] In the present invention, after vacuum brazing is completed, the temperature is preferably lowered to 350-400°C, and then cooled to room temperature with the furnace to obtain a nickel-based ceramic and metal connector, and further preferably lowered to 370-380°C, and then cooled to room temperature with the furnace to obtain a nickel-based ceramic and metal connector;

[0037] The rate of cooling to 350-400° C. is preferably 5-10° C. / min, more preferably 6-9° C. / min, and even more preferably 7-8° C. / min.

[0038] In the present invention, during vacuum brazing, the vacuum degree is preferably 10 -2 ~10 -3 Pa, more preferably 5×10 - 3 Pa.

[0039] The invention also provides a connecting piece of nickel-based ceramic and metal obtained by the method for connecting nickel-based ceramic and metal.

[0040] In the present invention, the nickel-based ceramic, the metal and the connecting layer have the same shape, preferably a plate, a rod or a tube.

[0041] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0042] Among the nickel-based ceramic raw materials, the particle sizes of boron carbide powder and titanium powder are 60 μm, the particle size of graphite powder is 65 μm, and the particle size of nickel powder is 70 μm; the purity of boron carbide powder, titanium powder, graphite powder and nickel powder is 99.7%.

[0043] Example 1

[0044] The nickel-based ceramic raw material is composed of boron carbide powder, titanium powder, graphite powder and nickel powder in a mass ratio of 1:0.6:1.8:0.4. The boron carbide powder, titanium powder, graphite powder and nickel powder are pressed into green bodies by isostatic pressing at 120MPa. The green bodies are sintered at 1000℃ for 1h in a nitrogen atmosphere (oxygen content is 150ppm) and then machined into nickel-based ceramic plates. In the connecting layer alloy foil, the mass ratio of silver, copper, titanium and molybdenum is 55:26:3.5:1; the thickness of the alloy foil is 30μm. The alloy foil, nickel-based ceramic plate and iron plate have the same shape (same length and width).

[0045] The surfaces to be welded of the nickel-based ceramic plate and the iron plate (area of ​​the surface to be welded is 5 mm×5 mm) were polished with 400#, 800#, and 1200# sandpapers in turn to remove impurities on the surfaces to be welded, and the nickel-based ceramic plate and the iron plate with smooth surfaces to be welded were obtained. The nickel-based ceramic plate and the iron plate with surface impurities removed were ultrasonically cleaned in anhydrous ethanol for 30 minutes at a frequency of 40KHz, and the nickel-based ceramic plate and the iron plate with clean surfaces to be welded were dried in an oven at 80°C for 30 minutes.

[0046] The alloy foil is placed between the nickel-based ceramic plate and the iron plate, the alloy foil contacts the nickel-based ceramic plate and the surface to be welded of the iron plate, 502 glue is applied between the alloy foil and the nickel-based ceramic, and between the alloy foil and the iron plate to fix them, and the welded parts are formed. The welded parts are placed in a vacuum heating furnace, and the heating furnace is evacuated to 10 -2Pa, the vacuum degree remained unchanged during the whole brazing process, the heating furnace was heated to 400℃ at a rate of 8℃ / min, vacuum brazing was performed at 400℃ for 7min, then heated to 970℃ at a rate of 10℃ / min, and vacuum brazing was performed at 970℃ for 10min. After vacuum brazing, the heating furnace was cooled to 350℃ at a rate of 6℃ / min, and then cooled to room temperature with the furnace to obtain a connection between nickel-based ceramic and metal.

[0047] The joint of the connecting piece of Example 1 is uniform and dense, without holes and microcracks, and the shear strength of the joint is 120 MPa.

[0048] Example 2

[0049] The nickel-based ceramic raw material is composed of boron carbide powder, titanium powder, graphite powder and nickel powder in a mass ratio of 1:0.9:1.4:0.5. The boron carbide powder, titanium powder, graphite powder and nickel powder are pressed into a green body by isostatic pressing at 120MPa. The green body is sintered at 1100℃ for 1h in a nitrogen atmosphere (oxygen content is 150ppm) and then machined into a nickel-based ceramic plate. In the connecting layer alloy foil, the mass ratio of silver, copper, titanium and molybdenum is 60:28:2.5:2; the thickness of the alloy foil is 60μm. The alloy foil, the nickel-based ceramic plate and the nickel plate have the same shape (same length and width).

[0050] The surfaces to be welded of the nickel-based ceramic plate and the nickel plate (area of ​​the surface to be welded is 5 mm×5 mm) were polished with 400#, 800#, and 1200# sandpapers in turn to remove impurities on the surface to be welded, and the nickel-based ceramic plate and the nickel plate with smooth surfaces to be welded were obtained. The nickel-based ceramic plate and the nickel plate with surface impurities removed were ultrasonically cleaned in anhydrous ethanol for 30 minutes at a frequency of 45KHz, and the nickel-based ceramic plate and the nickel plate with clean surfaces to be welded were dried in an oven at 70°C for 40 minutes.

[0051] The alloy foil is placed between the nickel-based ceramic plate and the nickel plate, the alloy foil contacts the nickel-based ceramic plate and the surface to be welded of the nickel plate, 502 glue is applied between the alloy foil and the nickel-based ceramic, and between the alloy foil and the nickel plate to fix them, and the welded parts are formed. The welded parts are placed in a vacuum heating furnace, and the heating furnace is evacuated to 10 -3 Pa, the vacuum degree remained unchanged during the whole brazing process, the heating furnace was heated to 450℃ at a rate of 13℃ / min, vacuum brazing was performed at 450℃ for 4min, then heated to 1050℃ at a rate of 13℃ / min, and vacuum brazing was performed at 1050℃ for 8min. After vacuum brazing, the heating furnace was cooled to 350℃ at a rate of 10℃ / min, and then cooled to room temperature with the furnace to obtain a connection between nickel-based ceramic and metal.

[0052] The joint of the connecting piece of Example 2 is uniform and dense, without holes and microcracks, and the shear strength of the joint is 122 MPa.

[0053] Example 3

[0054] The nickel-based ceramic raw material is composed of boron carbide powder, titanium powder, graphite powder and nickel powder in a mass ratio of 1:0.7:1.5:0.45. The boron carbide powder, titanium powder, graphite powder and nickel powder are pressed into green bodies by isostatic pressing at 120MPa. The green bodies are sintered at 1100℃ for 1h in a nitrogen atmosphere (oxygen content is 120ppm) and then machined into nickel-based ceramic plates. In the connecting layer alloy foil, the mass ratio of silver, copper, titanium and molybdenum is 58:27:3:1.5; the thickness of the alloy foil is 50μm. The alloy foil, nickel-based ceramic plate and titanium plate have the same shape (same length and width).

[0055] The surfaces to be welded of the nickel-based ceramic plate and the titanium plate (area of ​​the surface to be welded is 5 mm×5 mm) were polished with 400#, 800#, and 1200# sandpapers in turn to remove impurities on the surfaces to be welded, and the nickel-based ceramic plate and the titanium plate with smooth surfaces to be welded were obtained. The nickel-based ceramic plate and the titanium plate with surface impurities removed were ultrasonically cleaned in anhydrous ethanol for 30 minutes at a frequency of 40 KHz, and the nickel-based ceramic plate and the titanium plate with clean surfaces to be welded were dried in an oven at 80°C for 30 minutes.

[0056] The alloy foil is placed between the nickel-based ceramic plate and the titanium plate, the alloy foil contacts the nickel-based ceramic plate and the surface to be welded of the titanium plate, and 502 glue is applied between the alloy foil and the nickel-based ceramic, and between the alloy foil and the titanium plate to fix them, forming the welded parts. The welded parts are placed in a vacuum heating furnace, and the heating furnace is evacuated to 5×10 -2 Pa, the vacuum degree remains unchanged during the whole brazing process, the heating furnace is heated to 380℃ at a rate of 10℃ / min, vacuum brazing is performed at 380℃ for 5min, then the temperature is raised to 1000℃ at a rate of 12℃ / min, and vacuum brazing is performed at 1000℃ for 8min. After vacuum brazing, the heating furnace is cooled to 370℃ at a rate of 8℃ / min, and then cooled to room temperature with the furnace to obtain a connection between nickel-based ceramic and metal.

[0057] The joint of the connecting piece of Example 3 is uniform and dense, without holes and microcracks, and the room temperature shear strength of the joint is 130 MPa.

[0058] The room temperature three-point bending strength test of the nickel-based ceramic and metal connectors of Examples 1 to 3 was carried out using a Sansi electronic universal testing machine CMT4304. The span of the pre-connected component was 30 mm, the loading rate was 0.5 mm / min, and 6 specimens were tested for each example to take the average value. After testing, the room temperature three-point bending strength of the connector of Example 1 was 188 MPa, the room temperature three-point bending strength of the connector of Example 2 was 193 MPa, and the room temperature three-point bending strength of the connector of Example 3 was 199 MPa.

[0059] According to "Mechanical Properties Test of Welded Specimens of Pressure Equipment Products" (NB / T 47016-2011), the tensile strength test of the connectors of Examples 1 to 3 was carried out using an electronic universal material testing machine, and 6 specimens were tested for each example to take the average value. After testing, the tensile strength of the connector joint of Example 1 was 730MPa, the tensile strength of the connector joint of Example 2 was 735MPa, and the tensile strength of the connector joint of Example 3 was 741MPa.

[0060] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for connecting nickel-based ceramics to metals, characterized in that: The following steps are included: The connecting layer is placed between the nickel-based ceramic and the metal, and an adhesive is applied between the connecting layer and the nickel-based ceramic and between the connecting layer and the metal, and then vacuum brazing is performed to obtain a connecting piece of the nickel-based ceramic and the metal; The connecting layer is an alloy foil, which contains silver, copper, titanium and molybdenum; the nickel-based ceramic contains boron carbide powder, titanium powder, graphite powder and nickel powder; and the melting point of the metal does not exceed 2000°C.

2. The connection method according to claim 1, characterized in that: In the alloy foil, the mass ratio of silver, copper, titanium and molybdenum is 55-60:25-30:2-4:1-3; In the nickel-based ceramic, the mass ratio of boron carbide powder, titanium powder, graphite powder and nickel powder is 1:0.5-1:1-2:0.3-0.

6.

3. The connection method according to claim 1 or 2, characterized in that: The metal is titanium, nickel or iron.

4. The connection method according to claim 3, characterized in that: The thickness of the connecting layer is 20-80 μm.

5. The connection method according to claim 3, characterized in that: The vacuum brazing is performed sequentially at 400-450°C for the first vacuum brazing and at 960-1050°C for the second vacuum brazing; The heating rate of vacuum brazing is 8-15℃ / min.

6. The connection method according to claim 5, characterized in that: The first vacuum brazing time is 3 to 7 minutes, and the second vacuum brazing time is 5 to 10 minutes.

7. The connection method according to claim 5 or 6, characterized in that: After vacuum brazing is completed, the temperature is lowered to 350-400°C, and then cooled to room temperature along with the furnace to obtain a connection between nickel-based ceramic and metal; The rate of cooling to 350-400°C is 5-10°C / min.

8. The connection method according to claim 7, characterized in that: During vacuum brazing, the vacuum degree is 10 -2 ~10 -3 Pa.

9. A connecting piece of nickel-based ceramic and metal obtained by the method for connecting nickel-based ceramic and metal according to any one of claims 1 to 8.