A silicon carbide ceramic connector and its preparation method and application

Abstract

The present invention belongs to the technical field of ceramic welding, and discloses a silicon carbide connector, a preparation method thereof and an application. The method is to mix SiC, Si 3 N 4 with glass powder CAMZS to prepare a solder; apply a soldering flux to the areas to be welded of two silicon carbides to obtain a component to be connected; place the component to be connected in a heating furnace, and under a nitrogen atmosphere, apply mechanical pressure to the component to be connected, and perform welding treatment at 1500-1650 °C, and obtain a silicon carbide connector after cooling. The thickness of the connection layer of the connector is 10-60 μm, the shear strength of the connector at room temperature is 60-100 MPa, the shear strength under an inert atmosphere at 1000 °C is 70-110 MPa, and the room temperature shear strength of the connection layer is 40-70 MPa after three times of water quenching at 800 °C. The silicon carbide connector can be applied in the fields of heat exchange, aviation, aerospace or military industry.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic connection, and more specifically, to a silicon carbide ceramic connector and a preparation method and application thereof. Background Art

[0002] Silicon carbide ceramics have excellent properties such as high strength, oxidation resistance, wear resistance, high temperature resistance and high thermal conductivity, and are widely used in aerospace, nuclear energy, high-temperature heat exchange and other fields. With the rapid development of industry, there are increasingly higher requirements for the structure and size of silicon carbide ceramic components. However, under the current level of industrial development, the preparation of large and complex silicon carbide components is difficult and the production cost is high. The development of silicon carbide ceramic welding technology is an effective way to solve the above problems.

[0003] Si 3 N 4 / SiC composite ceramics are a kind of ceramic material with high strength, high temperature resistance, chemical corrosion resistance and high temperature oxidation resistance. 3 N 4 / SiC composite ceramics as the connecting layer material can obtain SiC connectors with excellent connection strength and high temperature resistance. 3 N 4 / SiC is a difficult sintering material. In order to obtain dense Si 3 N 4 In order to form a SiC / SiC composite ceramic connecting layer and achieve a tight and high-strength connection between the connecting layer and the base material, it is usually necessary to apply a high connection pressure (≥10MPa) to the parts during the connection process, and to introduce traditional low-temperature sintering aids to promote sintering densification, which severely limits the design range of the shape and size of SiC connectors, and also limits the application of SiC connectors in high temperature, corrosive and other service environments. Summary of the invention

[0004] In order to solve the problem of Si 3 N 4 / SiC composite ceramics are used as the connecting layer material. It is difficult to achieve Si under low-pressure connection conditions. 3 N 4 The primary purpose of the present invention is to provide a method for preparing a silicon carbide connector in order to improve the densification of the SiC connecting layer and achieve effective connection with the SiC base material, and to reduce the high temperature performance and corrosion resistance of the connecting layer after the introduction of traditional low temperature sintering aids.

[0005] Another object of the present invention is to provide the above method for preparing a silicon carbide connector.

[0006] Another object of the present invention is to provide applications of the above silicon carbide connecting piece.

[0007] The object of the present invention is achieved by the following technical solutions:

[0008] A preparation method of a silicon carbide connector, comprising the following specific steps:

[0009] S1. Mix SiC powder, Si 3 N 4 powder and CAMZS glass powder with absolute ethanol as a solvent by roll ball milling to prepare a solder; the SCAMZ glass powder is CaO - Al 2 O 3 -MgO - ZrO 2 -SiO 2 ; the mass ratio of CaO powder, Al 2 O 3 powder, MgO powder, ZrO 2 powder and SiO 2 powder is (8 - 12):(16 - 24):(9 - 13):(1 - 5):(46 - 66); the mass ratio of SiC, Si 3 N 4 and CAMZS is (3 - 6):(1 - 3):(11 - 16);

[0010] S2. Apply the flux to the areas to be welded of two silicon carbides, and place them according to the structure of the product to be formed to obtain a component to be connected;

[0011] S3. Put the component to be connected into a heating furnace, apply mechanical pressure to the component to be connected in a nitrogen atmosphere, and perform welding treatment at 1500 - 1650 °C, and obtain a silicon carbide connector after cooling.

[0012] Preferably, in step S1, the SCAMZ glass powder is prepared by mixing CaO powder, Al 2 O 3 powder, MgO powder, ZrO 2 powder and SiO 2 powder, keeping them at 1550 - 1650 °C for 0.5 - 2 h, quenching with water and then grinding, and further refining them by planetary ball milling at 300 rpm / 24 h and passing through a 100 - mesh sieve.

[0013] More preferably, the mass ratio of the CaO powder, Al 2 O 3 powder, MgO powder, ZrO 2 powder and SiO 2 powder is 9:20:11:2.5:57.5.

[0014] Preferably, in step S1, the particle size of the SiC is 30 - 1000 nm, and the particle size of the Si 3 N 4 is 30 - 1000 nm.

[0015] Preferably, the coating method in step S2 is screen printing or spraying.

[0016] Preferably, the pressure of the nitrogen atmosphere in step S3 is 0.05 - 0.15 MPa; the mechanical pressure is 0.1 - 1 MPa.

[0017] Preferably, the specific process of the welding treatment in step S3 is to heat up to 1000 °C at a rate of 1 - 10 °C / min, then heat up to 1500 - 1650 °C at a rate of 1 - 5 °C / min and hold for 10 - 60 min, and then cool down to 800 °C at a rate of 1 - 5 °C / min and cool with the furnace.

[0018] A silicon carbide connector, which is prepared by the described method.

[0019] Preferably, the thickness of the connection layer in the silicon carbide ceramic connector is 10 - 60 μm, the helium leakage rate of the connection layer is 1.0×10 -12 ~1.0×10 -9 Pa·m 3 / s, the shear strength of the connection layer at room temperature is 60 - 100 MPa, the high-temperature shear strength in an inert atmosphere at 1000 °C is 70 - 110 MPa, and the shear strength of the connection layer at room temperature after 3 times of water quenching at 800 °C is 40 - 70 MPa.

[0020] The application of the described silicon carbide connector in high-temperature heat exchange or space fields.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention uses a sintering aid CaO - Al 2 O 3 -MgO - ZrO 2 -SiO 2 glass system, which has good wettability with the base material SiC and has good high-temperature resistance and corrosion resistance. As the grain boundary phase of the connection layer material, it can improve the high-temperature resistance and corrosion resistance of the connection layer and expand the application range of this technology;

[0023] 2. The method of the present invention is different from the traditional sintering of SiC and Si 3 N 4 ceramics. By reasonably designing the proportions of SiC, Si 3 N 4 and CAMZS, during the welding process, the excess sintering aid is extruded from the connection area under the action of mechanical pressure, obtaining a high-density and high-strength Si 3 N 4 / SiC composite ceramic connection layer with firm interfacial bonding. Specific Embodiments

[0024] The content of the present invention will be further described below in conjunction with specific embodiments, but it should not be construed as a limitation to the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well-known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the technical field.

[0025] Example 1

[0026] 1. Mix CaO, Al 2 O 3 , MgO, ZrO 2 , SiO 2 powders in a mass ratio of 9:20:11:2.5:57.5, then keep them at 1600 °C for 1 h, quench with water, grind the quenched glass using a mortar, and then refine it using a planetary ball mill at 300 rpm / 24 h. Sieve the glass powder through a 100-mesh sieve. Mix SiC (particle size 500 nm) and Si 3 N 4 (particle size 100 nm) and CaO - Al 2 O 3 - MgO - ZrO 2 - SiO 2 (CAMZS) glass powders in a mass ratio of 20:5:75, use absolute ethanol as a solvent, and mix them according to the roll ball milling process of 100 rpm / 24 h to obtain a solder.

[0027] 2. Coating and Assembly: Spray the solder on the surface of SiC to be welded. The actual content of the solder is 1.0 mg / cm 2 . Place two silicon carbides according to the structure of the product to be formed to obtain a component to be connected;

[0028] 3. Welding: Put the component to be connected into a heating furnace, under a mechanical pressure of 0.5 MPa, carry out welding treatment on the component to be connected in a nitrogen atmosphere of 0.15 MPa. The welding process is to heat up to 1000 °C at a rate of 5 °C / min, then heat up to 1600 °C at a rate of 2.5 °C / min and keep it for 30 min, and then cool down to 800 °C at a rate of 2.5 °C / min and cool with the furnace to obtain a silicon carbide connector with a connection layer of Si 3 N 4 / SiC.

[0029] The connection layer thickness of the silicon carbide connector in this example is 20 μm, and the helium leakage rate of the connection layer is 1.0×10 - 12 Pa·m 3 / s, the shear strengths of the bonding layer at room temperature and in an argon atmosphere at 1000 °C are 90 MPa and 110 MPa respectively. After three water quenches at 800 °C, the shear strength of the bonding layer at room temperature is 70 MPa.

[0030] Example 2

[0031] 1. Preparation of solder: Mix CaO, Al 2 O 3 , MgO, ZrO 2 , SiO 2 powders in a mass ratio of 11:22:12:5:50, then hold at 1600 °C for 1 h, water quench, grind the quenched glass using a mortar, and then refine it through planetary ball milling at 300 rpm for 24 h. Screen the glass powder through a 100-mesh sieve. Mix SiC with a particle size of 300 nm, Si 3 N 4 with a particle size of 50 nm and CAMZS glass powder in a mass ratio of 25:5:70. Using absolute ethanol as a solvent, mix them according to the roll ball milling process at 100 rpm for 24 h to obtain the solder.

[0032] 2. Coating and assembly: Spray the solder onto the surface of the SiC to be welded. The actual content of the solder is 1.5 mg / cm 2 . Place two silicon carbides according to the structure of the product to be formed to obtain the component to be joined;

[0033] 3. Welding: Put the component to be joined into a heating furnace, under a mechanical pressure of 0.1 MPa, carry out welding treatment on the component to be joined in a nitrogen atmosphere of 0.1 MPa. The welding process is to heat up to 1000 °C at a rate of 10 °C / min, then heat up to 1650 °C at a rate of 5 °C / min, hold for 60 min, and then cool down to 800 °C at a rate of 5 °C / min, and cool with the furnace to obtain a silicon carbide connector with a bonding layer of Si 3 N 4 / SiC.

[0034] The thickness of the bonding layer of the silicon carbide connector in this example is 30 μm, and the helium leakage rate of the bonding layer is 1.0×10 - 11 Pa·m 3 / s. The shear strengths of the bonding layer at room temperature and in an argon atmosphere at 1000 °C are 80 MPa and 85 MPa respectively. After three water quenches at 800 °C, the shear strength of the bonding layer at room temperature is 60 MPa.

[0035] Example 3

[0036] 1. Preparation of solder: Mix CaO, Al 2 O 3 , MgO, ZrO2 , SiO 2 powder is mixed in a mass ratio of 9:20:11:2.5:57.5, then kept at 1600 °C for 1 h, water quenched, the quenched glass is ground using a mortar, and then refined by planetary ball milling at 300 rpm / 24 h, and the glass powder is sieved through a 100-mesh sieve. SiC with a particle size of 1000 nm and Si 3 N 4 and CAMZS glass powder are mixed in a mass ratio of 25:10:65, using anhydrous ethanol as a solvent, and mixed by a roller ball milling process at 100 rpm / 24 h to obtain a solder.

[0037] 2. Coating and assembly: The solder is coated on the surface of SiC to be welded by spraying, and the actual content of the solder is 3.0 mg / cm 2 , and two silicon carbides are placed according to the structure of the product to be formed to obtain a component to be connected;

[0038] 3. Welding: The component to be connected is placed in a heating furnace, and under a mechanical pressure of 1 MPa, the component to be connected is welded in a nitrogen atmosphere of 0.1 MPa. The welding process is to heat up to 1000 °C at a rate of 10 °C / min, then heat up to 1650 °C at a rate of 2.5 °C / min, keep it for 60 min, and then cool down to 800 °C at a rate of 2.5 °C / min, and cool with the furnace to obtain a silicon carbide connector with a connection layer of Si 3 N 4 / SiC.

[0039] The thickness of the connection layer of the silicon carbide connector in this example is 50 μm, the helium leakage rate of the connection layer is 5.0×10 - 10 Pa·m 3 / s, the shear strengths of the connection layer at room temperature and in a nitrogen atmosphere at 1000 °C are 65 MPa and 80 MPa respectively, and the room temperature shear strength of the connection layer after 3 times of water quenching at 800 °C is 50 MPa.

[0040] Example 4

[0041] 1. Preparation of solder: CaO, Al 2 O 3 , MgO, ZrO 2 , SiO 2 powder is mixed in a mass ratio of 8:16:9:1:66, then kept at 1600 °C for 1 h, water quenched, the quenched glass is ground using a mortar, and then refined by planetary ball milling at 300 rpm / 24 h, and the glass powder is sieved through a 100-mesh sieve. SiC with a particle size of 100 nm and Si 3 N 4Mix CaO, Al 2 O 3 , MgO, ZrO 2 , SiO 2 powders in a mass ratio of 9:20:11:2.5:57.5, then heat at 1600 °C for 1 h, water quench, grind the quenched glass using a mortar, and then refine it using a planetary ball mill at 300 rpm / 24 h. Screen the glass powder through a 100-mesh sieve. Mix 500-nm-sized SiC and 100-nm-sized Si 3 N 4 and CAMZS glass powder in a mass ratio of 30:15:55, use absolute ethanol as a solvent, and mix them according to the roll ball milling process at 100 rpm / 24 h to obtain a solder.

[0042] 2. Coating and assembly: Spray the solder onto the surface of the SiC to be welded. The actual content of the solder is 0.5 mg / cm 2 , place two silicon carbides according to the structure of the product to be formed to obtain the components to be joined;

[0043] 3. Welding: Put the components to be joined into a heating furnace, under a mechanical pressure of 0.1 MPa, and carry out welding treatment on the components to be joined in a nitrogen atmosphere of 0.05 MPa. The welding process is to heat up to 1000 °C at a rate of 5 °C / min, then heat up to 1500 °C at a rate of 3 °C / min and hold for 60 min, and then cool down to 800 °C at a rate of 3 °C / min and cool with the furnace to obtain a silicon carbide connector with a connection layer of Si 3 N 4 / SiC.

[0044] The thickness of the connection layer of the silicon carbide connector in this example is 15 μm, the helium leakage rate of the connection layer is 4.0×10 - 12 Pa·m 3 / s. The shear strengths of the connection layer at room temperature and in an argon atmosphere at 1000 °C are 70 MPa and 95 MPa respectively. After three water quenches at 800 °C, the shear strength of the connection layer at room temperature is 55 MPa.

[0045] Example 5

[0046] 1. Preparation of solder: Mix CaO, Al 2 O 3 , MgO, ZrO 2 , SiO 2 powders in a mass ratio of 9:20:11:2.5:57.5, then heat at 1600 °C for 1 h, water quench, grind the quenched glass using a mortar, and then refine it using a planetary ball mill at 300 rpm / 24 h. Screen the glass powder through a 100-mesh sieve. Mix 500-nm-sized SiC and 100-nm-sized Si 3 N 4 and CAMZS glass powder in a mass ratio of 30:15:55, use absolute ethanol as a solvent, and mix them according to the roll ball milling process at 100 rpm / 24 h to obtain a solder.

[0047] 2. Coating and assembly: Spray the solder onto the surface of the SiC to be welded. The actual content of the solder is 0.5 mg / cm 2, place two silicon carbides according to the structure of the product to be formed to obtain the component to be joined;

[0048] 3. Welding: Put the component to be joined into a heating furnace, and under a mechanical pressure of 1 MPa and in a nitrogen atmosphere of 0.05 MPa, perform welding treatment on the component to be joined. The welding process is to heat up to 1630 °C at a rate of 2.5 °C / min, hold for 60 min, then cool down to 800 °C at a rate of 2.5 °C / min, and cool with the furnace to obtain a silicon carbide connector with a joining layer of Si 3 N 4 / SiC.

[0049] The thickness of the joining layer of the silicon carbide connector in this embodiment is 10 μm, and the helium leakage rate of the joining layer is 6.0×10 - 10 Pa·m 3 / s. The shear strengths of the joining layer at room temperature and in an argon atmosphere at 1000 °C are 80 MPa and 100 MPa respectively. After three water quenches at 800 °C, the shear strength of the joining layer at room temperature is 60 MPa.

[0050] In the silicon carbide ceramic connector of the present invention, the thickness of the joining layer is 10 - 60 μm, the helium leakage rate of the joining layer is 1.0×10 -12 ~1.0×10 -9 Pa·m 3 / s. The shear strength of the joining layer at room temperature is 60 - 100 MPa, the high-temperature shear strength in an inert atmosphere at 1000 °C is 70 - 110 MPa, and after three water quenches at 800 °C, the shear strength of the joining layer at room temperature is 40 - 70 MPa.

[0051] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A preparation method of a silicon carbide connector, characterized in that, it includes the following specific steps: S1. Mix SiC powder, Si 3 N 4 powder and CAMZS glass powder with absolute ethanol as the solvent and prepare the solder by roll ball milling; the CAMZS glass powder is CaO - Al 2 O 3 -MgO - ZrO 2 -SiO 2 ; the mass ratio of CaO powder, Al 2 O 3 powder, MgO powder, ZrO 2 powder, SiO 2 powder is (8 - 12):(16 - 24):(9 - 13):(1 - 5):(46 - 66); the mass ratio of SiC powder, Si 3 N 4 powder and CAMZS glass powder is (3 - 6):(1 - 3):(11 - 16); the said CAMZS glass powder is prepared by mixing CaO powder, Al 2 O 3 powder, MgO powder, ZrO 2 powder and SiO 2 powder, keeping warm at 1550 - 1650 °C for 0.5 - 2 h, quenching with water and then grinding, and further refining by planetary ball milling at 300 rpm / 24 h and passing through a 100 - mesh sieve; S2. Apply solder to the areas to be welded of two silicon carbides to obtain a component to be connected; S3. Place the components to be joined into a heating furnace, and apply mechanical pressure to the components to be joined in a nitrogen atmosphere, where the pressure of the nitrogen atmosphere is 0.05 - 0.15 MPa; the pressure of the mechanical pressure is 0.1 - 1 MPa; perform welding treatment at 1500 - 1650 °C, and obtain a silicon carbide connector after cooling; the thickness of the connection layer in the silicon carbide connector is 10 - 60 μm, the helium leak rate of the connection layer is 1.0×10 -12 ~1.0×10 -9 Pa·m 3 / s, the shear strength at room temperature of the connection layer is 60 - 100 MPa, the high-temperature shear strength in an inert atmosphere at 1000 °C is 70 - 110 MPa, and the shear strength at room temperature of the connection layer after 3 times of water quenching at 800 °C is 40 - 70 MPa.

2. The preparation method of the silicon carbide connector according to claim 1, characterized in that, The CaO powder, Al 2 O 3 powder, MgO powder, ZrO 2 powder and SiO 2 powder have a mass ratio of 9:20:11:2.5:57.

5.

3. The preparation method of the silicon carbide connector according to claim 1, characterized in that, The particle size of the SiC powder described in step S1 is 30 to 1000 nm, and the particle size of the Si 3 N 4 powder is 30 to 1000 nm.

4. The preparation method of the silicon carbide connector according to claim 1, characterized in that, the coating method in step S2 is screen printing or spraying.

5. The preparation method of the silicon carbide connector according to claim 1, characterized in that, the specific process of the welding treatment in step S3 is to heat up to 1000 °C at a rate of 1-10 °C / min, then heat up to 1500-1650 °C at a rate of 1-5 °C / min and keep warm for 10-60 min, and then cool down to 800 °C at a rate of 1-5 °C / min and cool with the furnace.

6. A silicon carbide connector, characterized in that, the connector is prepared by the method according to any one of claims 1-5.

7. Application of the silicon carbide connector according to claim 6 in the fields of high-temperature heat exchange or space.