A silicon carbide ceramic weldment resistant to hydrothermal corrosion and high-temperature oxidation, its preparation method and application

Abstract

This invention belongs to the field of ceramic welding technology, and discloses a silicon carbide ceramic weldment resistant to hydrothermal corrosion and high-temperature oxidation, its preparation method, and its application. The method involves ball milling and mixing Al2O3, MgO, CaO, HfO2, Nd2O3, and SiO2 powders, followed by water quenching at 1600–1700℃ to obtain glass. This glass is then refined through grinding and sieving to obtain glass powder. The glass powder is then dry-pressed to form a glass green body. The glass green body is placed on two SiC ceramic areas to be welded, and the two SiC ceramics are then arranged according to the structure of the product to be formed, resulting in a component to be joined. This component is then placed in a heating furnace and subjected to mechanical pressure and heat treatment at 1350–1600℃ in a protective atmosphere to obtain the silicon carbide ceramic weldment. This silicon carbide ceramic weldment exhibits excellent resistance to hydrothermal corrosion and high-temperature oxidation, and can be applied in high-temperature heat exchange and nuclear energy fields.

Description

Technical Field

[0001] This invention belongs to the field of ceramic joining technology, and more specifically, relates to a silicon carbide ceramic weldment resistant to hydrothermal corrosion and high-temperature oxidation, its preparation method, and its application. Background Technology

[0002] Silicon carbide ceramics possess excellent properties such as high strength, outstanding high-temperature performance, oxidation resistance, and high thermal conductivity, making them widely used in aerospace, metallurgy, and other fields. With rapid industrial development, there are increasingly stringent requirements for the structure and dimensions of silicon carbide ceramic components. However, due to the low ductility and high melting point of silicon carbide ceramics, the fabrication of large and complex silicon carbide components is difficult and costly. Developing silicon carbide ceramic welding technology is an effective way to solve these problems. Furthermore, developing silicon carbide ceramic welding technology can improve the reliability and durability of ceramic structural components. Therefore, developing silicon carbide ceramic welding technology is of great significance to the development of national industry.

[0003] Currently, various silicon carbide ceramic joining technologies have been developed based on different solder types, including active metal brazing, refractory metal diffusion welding, glass welding, MAX phase welding, nano-impregnation transient eutectic phase welding, reactive bonding, and precursor bonding. Among these, glass welding has significant advantages in welding large and complex silicon carbide ceramic components due to its advantages such as requiring little or no bonding pressure during the welding process, low requirements on the surface condition of the base material, low requirements on welding equipment, and a dense bonding layer with an adjustable coefficient of thermal expansion. However, the high-temperature steam oxidation resistance of existing publicly available glass-welded silicon carbide ceramic components is generally poor, especially its resistance to high-temperature and high-pressure hydrothermal corrosion, which fails to meet the application requirements in specific environments. This limits the application of glass-welded silicon carbide ceramic welding technology in high-temperature heat exchange and nuclear energy fields. Therefore, there is an urgent need to develop methods for preparing silicon carbide ceramic components resistant to high-temperature oxidation and hydrothermal corrosion. Summary of the Invention

[0004] To address the shortcomings of existing glass-based welded silicon carbide ceramic components in terms of resistance to hydrothermal corrosion and high-temperature oxidation, the primary objective of this invention is to provide a method for preparing silicon carbide ceramic welded components that are resistant to hydrothermal corrosion and high-temperature oxidation.

[0005] Another object of the present invention is to provide the method described above for preparing silicon carbide ceramic welded parts.

[0006] Another object of the present invention is to provide the application of the above-mentioned silicon carbide ceramic weldment.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A method for preparing silicon carbide ceramic welded parts resistant to hydrothermal corrosion and high-temperature oxidation includes the following specific steps:

[0009] S1. Al2O3, MgO, CaO, HfO2, Nd2O3 and SiO2 powders are ball-milled and mixed, and then water-quenched at 1600-1700℃ to obtain glass. After grinding and refining and sieving, glass powder is obtained.

[0010] S2. The glass powder is dry-pressed at 1-100MPa to obtain a glass preform. The glass block is placed in the welding area of ​​two SiC ceramics. Then the two SiC ceramics are placed according to the structure of the product to be formed to obtain the component to be connected.

[0011] S3. The components to be connected are placed in a heating furnace and subjected to heat treatment at 1350-1600℃ under a mechanical pressure of 0.01-1MPa in a protective atmosphere to obtain silicon carbide ceramic welded parts.

[0012] Preferably, the mass ratio of Al2O3, MgO, CaO, HfO2, Nd2O3 and SiO2 in step S1 is (15-20):(9-11):(8-10):(1-10):(1-6):(43-66).

[0013] Preferably, the sieve in step S1 has a mesh size of 50 to 400 mesh, and the water quenching time is 0.5 to 2 hours.

[0014] Preferably, the dry pressing time in step S2 is 1 to 10 minutes; the thickness of the glass preform is 0.5 to 3 mm.

[0015] Preferably, the protective atmosphere in step S3 is one or more of nitrogen, helium or argon, and the pressure of the protective atmosphere is 0.1 to 0.5 MPa.

[0016] Preferably, the specific process of the heat treatment in step S3 is as follows: heat up to 1000°C at 1-10°C / min, then heat up to 1350-1600°C at 1-5°C / min and hold for 5-60 minutes, then cool down to 1100°C at 1-3°C / min, then cool down to 400°C at 1-5°C / min, and then cool with the furnace.

[0017] A silicon carbide ceramic weldment resistant to hydrothermal corrosion and high-temperature oxidation, wherein the ceramic connector is prepared by the method described above.

[0018] Preferably, the thickness of the connecting layer of the silicon carbide ceramic weldment is 1–50 μm, and the helium leakage rate of the weldment with a wall thickness of 0.5–5 mm is 1.0 × 10⁻⁶. -12 ~1.0×10 -9 Pa·m 3 / s, the shear strength of the welded parts is 70~110MPa. After static corrosion in pure water in an autoclave at 360℃ / 18.6MPa / 7d, the single-sided dimension of the bonding layer degrades to 1~5μm. After heat treatment in an air environment at 800℃ for 3d, the room temperature shear strength of the welded parts does not decrease significantly.

[0019] The aforementioned silicon carbide ceramic joints, resistant to hydrothermal corrosion and high-temperature oxidation, are used in high-temperature heat exchange or nuclear energy fields.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. This invention discloses for the first time a novel glass system, Al2O3-MgO-CaO-HfO2-Nd2O3-SiO2, suitable for welding silicon carbide ceramics. Based on a deep understanding of glass materials and silicon carbide ceramic welding technology, the composition and proportion of the glass are precisely designed. First, glass powder is prepared by water quenching. Then, the glass powder is dry-pressed to obtain a glass preform. The glass preform is then placed on the welding areas of two SiC ceramics to obtain the component to be welded. Under certain mechanical pressure and in a protective atmosphere, high-temperature welding is performed. After cooling, the silicon carbide ceramic welded part is obtained.

[0022] 2. The silicon carbide welded parts obtained by using Al2O3-MgO-CaO-HfO2-Nd2O3-SiO2 glass as solder in this invention have good hydrothermal corrosion resistance and high-temperature oxidation resistance, which solves the problem of insufficient hydrothermal corrosion resistance and high-temperature water vapor oxidation resistance of existing glass-based welded silicon carbide ceramic parts. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the silicon carbide ceramic welded parts in Examples 1 and 2.

[0024] Figure 2 This is a microstructure diagram of the welded area of ​​the silicon carbide ceramic weldment in Example 1.

[0025] Figure 3 This is a microstructure diagram of the welded area of ​​the silicon carbide ceramic weldment in Example 2. Detailed Implementation

[0026] The present invention will be further described below with reference to specific embodiments, but these should not be construed as limiting the 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 this technical field.

[0027] Example 1

[0028] 1. Al2O3, MgO, CaO, HfO2, Nd2O3 and SiO2 powders in a mass ratio of 16:10:9:2:2:61 are mixed, kept at 1650℃ for 1 hour and then quenched with water to obtain glass. The glass is then ground and refined and passed through a 100-mesh sieve to obtain glass powder.

[0029] 2. The glass powder is dry-pressed at 50MPa and held at that pressure for 5 minutes using a tablet press to obtain a glass preform with a thickness of 1.5mm.

[0030] 3. Place the glass preform between the two SiC ceramic areas to be welded, and then place the two SiC ceramics according to the structure of the product to be formed to obtain the assembly to be connected;

[0031] 4. Place the components to be connected into a heating furnace. Under a mechanical pressure of 0.1 MPa and in an argon atmosphere, heat the components at a rate of 5°C / min to 1000°C, then heat them at a rate of 5°C / min to 1450°C and hold for 20 minutes for heat treatment. Then, heat the components at a rate of 2.5°C / min to 1100°C and at a rate of 4°C / min to 400°C. Cool the components in the furnace to obtain silicon carbide ceramic welded parts.

[0032] Figure 1 This is a schematic diagram of the structure of the silicon carbide ceramic welded component of the present invention. From... Figure 1 As can be seen from the diagram, the silicon carbide ceramic welded component consists of two annular SiC ceramic sheets connected by a connecting layer. The wall thickness refers to the thickness of the annular SiC ceramic sheet in the radial direction. The shape of both the connecting layer and the annular SiC ceramic sheet in the axial direction is annular and their dimensions are the same, that is, the initial thickness of the connecting layer in the radial direction is 0.5 to 5 mm. Figure 2 This is a microstructure diagram of the welded area of ​​the silicon carbide ceramic weldment in Example 1, as shown below. Figure 2 As shown, the thickness of the bonding layer in the silicon carbide ceramic weldment of this embodiment is 12 μm. The helium leakage rate of the weldment with a wall thickness of 2.5 mm is 5.0 × 10⁻⁶. -11 Pa·m 3 The welded part has a room temperature shear strength of 95 MPa. After static corrosion in pure water at 360℃ / 18.6 MPa / 7d in an autoclave, the single-sided dimension of the welded part's connection layer degrades by 4.5 μm. After heat treatment in an air environment at 800℃ for 3d, the welded part has a room temperature shear strength of 92 MPa. It can be used in high-temperature heat exchange or nuclear energy fields.

[0033] Example 2

[0034] 1. Al2O3, MgO, CaO, HfO2, Nd2O3 and SiO2 powders in a mass ratio of 18:11:10:1.5:1:58.5 were mixed, kept at 1650℃ for 1 hour and then water quenched to obtain glass. The glass was then ground and refined and passed through a 100-mesh sieve to obtain glass powder.

[0035] 2. The glass powder is dry-pressed at 60MPa and held at that pressure for 5 minutes using a tablet press to obtain a glass preform with a thickness of 1.5mm.

[0036] 3. Place the glass preform on the welding areas of the two SiC ceramics, and then place the two SiC ceramics according to the structure of the product to be formed to obtain the assembly to be connected;

[0037] 4. Place the components to be connected into a heating furnace. Under a mechanical pressure of 0.05 MPa and in an argon atmosphere, heat the components at a rate of 10°C / min to 1000°C, then heat them at a rate of 5°C / min to 1480°C and hold for 15 minutes for heat treatment. Then, heat the components at a rate of 3°C / min to 1100°C and at a rate of 5°C / min to 400°C. Cool the components in the furnace to obtain silicon carbide ceramic welded parts.

[0038] Figure 3 This is a microstructure diagram of the welded area of ​​the silicon carbide ceramic weldment in Example 2. Figure 3 As shown, in this embodiment, the thickness of the connecting layer of the silicon carbide ceramic weldment is 11 μm, and the helium leakage rate of the weldment with a wall thickness of 2.5 mm is 5.0 × 10⁻⁶. -12 Pa·m 3 The welded part has a room temperature shear strength of 102 MPa. After static corrosion in pure water at 360℃ / 18.6 MPa / 7d in an autoclave, the single-sided dimension of the welded part's connection layer degrades by 5 μm. After heat treatment in an air environment at 800℃ for 3d, the welded part has a room temperature shear strength of 96 MPa. It can be used in high-temperature heat exchange or nuclear energy fields.

[0039] Example 3

[0040] 1. Al2O3, MgO, CaO, HfO2, Nd2O3 and SiO2 powders in a mass ratio of 18:11:10:5:3:53 are mixed, melted and held at 1620℃ for 2 hours, and then water-quenched to obtain glass. The glass is then ground and refined and passed through a 200-mesh sieve to obtain glass powder.

[0041] 2. The glass powder is dry-pressed at 30MPa and held at that pressure for 3 minutes using a tablet press to obtain a glass preform with a thickness of 2.5mm.

[0042] 3. Place the glass preform on the welding areas of the two SiC ceramics, and then place the two SiC ceramics according to the structure of the product to be formed to obtain the assembly to be connected;

[0043] 4. Place the components to be connected into a heating furnace. Under a mechanical pressure of 0.1 MPa and in an argon atmosphere, heat the components at a rate of 10°C / min to 1000°C, then heat them at a rate of 5°C / min to 1520°C and hold for 5 minutes for heat treatment. Then, heat the components at a rate of 2°C / min to 1100°C and at a rate of 5°C / min to 400°C. Cool the components in the furnace to obtain silicon carbide ceramic welded parts.

[0044] In this embodiment, the silicon carbide ceramic weldment has a bonding layer thickness of 22 μm and a wall thickness of 0.9 mm, resulting in a helium leakage rate of 6.5 × 10⁻⁶. -10 Pa·m 3 The welded part has a room temperature shear strength of 95 MPa. After static corrosion in pure water at 360℃ / 18.6 MPa / 7d in an autoclave, the single-sided dimension of the welded part's connection layer degrades by 2.5 μm. After heat treatment in an air environment at 800℃ for 3d, the welded part has a room temperature shear strength of 90 MPa. It can be used in high-temperature heat exchange or nuclear energy fields.

[0045] Example 4

[0046] 1. Al2O3, MgO, CaO, HfO2, Nd2O3 and SiO2 powders in a mass ratio of 20:9:9:10:5:47 are mixed, kept at 1700℃ for 0.5h and then quenched with water to obtain glass. The glass is then ground and refined and passed through a 200-mesh sieve to obtain glass powder.

[0047] 2. The glass powder is dry-pressed at 60MPa using a tablet press and held at that pressure for 10 minutes to obtain a glass preform with a thickness of 2mm.

[0048] 3. Place the glass preform on the welding areas of the two SiC ceramics, and then place the two SiC ceramics according to the structure of the product to be formed to obtain the assembly to be connected;

[0049] 4. Place the components to be connected into a heating furnace, and heat them to 1000℃ at 10℃ / min under a nitrogen atmosphere with a mechanical pressure of 0.1MPa. Then heat them to 1500℃ at 5℃ / min and hold for 5 minutes for heat treatment. Then cool them down to 1100℃ at 2℃ / min and to 400℃ at 5℃ / min. After cooling down in the furnace, the silicon carbide ceramic welded parts are obtained.

[0050] In this embodiment, the thickness of the connecting layer of the silicon carbide ceramic weldment is 25 μm, and the helium leakage rate of the weldment with a wall thickness of 1.5 mm is 6.5 × 10⁻⁶. -10 Pa·m 3The welded part has a room temperature shear strength of 82 MPa. After static corrosion in pure water at 360℃ / 18.6 MPa / 7d in an autoclave, the welded part's joint layer degrades by 2.0 μm. After heat treatment in air at 800℃ for 3d, the welded part has a room temperature shear strength of 82 MPa. It can be applied in high-temperature heat exchange or nuclear energy fields.

[0051] Example 5

[0052] 1. Al2O3, MgO, CaO, HfO2, Nd2O3 and SiO2 powders in a mass ratio of 18:11:10:10:6:45 are mixed, kept at 1650℃ for 0.5h and then quenched with water to obtain glass. The glass is then ground and refined and passed through a 100-mesh sieve to obtain glass powder.

[0053] 2. The glass powder is dry-pressed at 60MPa using a tablet press and held at that pressure for 10 minutes to obtain a glass preform with a thickness of 3.0mm;

[0054] 3. Place the glass preform on the welding areas of the two SiC ceramics, and then place the two SiC ceramics according to the structure of the product to be formed to obtain the assembly to be connected;

[0055] 4. Place the components to be connected into a heating furnace, and heat them to 1000℃ at 5℃ / min under a nitrogen atmosphere with a mechanical pressure of 0.1MPa. Then heat them to 1550℃ at 3℃ / min and hold for 5 minutes for heat treatment. Then cool them down to 1100℃ at 3℃ / min and to 400℃ at 5℃ / min. Cool them down with the furnace to obtain silicon carbide ceramic welded parts.

[0056] In this embodiment, the thickness of the connecting layer of the silicon carbide ceramic weldment is 35 μm, and the helium leakage rate of the weldment with a wall thickness of 4.0 mm is 2.0 × 10⁻⁶. -10 Pa·m 3 The welded part has a room temperature shear strength of 75 MPa. After static corrosion in pure water at 360℃ / 18.6 MPa / 7d in an autoclave, the single-sided dimension of the welded part's connection layer degrades by 1.5 μm. After heat treatment in an air environment at 800℃ for 3d, the welded part has a room temperature shear strength of 73 MPa. It can be used in high-temperature heat exchange and nuclear energy fields.

[0057] The thickness of the connecting layer in the silicon carbide ceramic weldment of this invention is 1–50 μm, and the helium leakage rate of the weldment with a wall thickness of 0.5–5 mm is 1.0 × 10⁻⁶. -12 ~1.0×10 -9 Pa·m 3The shear strength of the welded parts is 70-110 MPa. After static corrosion in pure water at 360℃ / 18.6 MPa / 7d in an autoclave, the single-sided dimension of the bonding layer degrades by 1-5 μm. After heat treatment in air at 800℃ for 3d, the room temperature shear strength of the welded parts is 73-96 MPa. It can be used in high-temperature heat exchange or nuclear energy fields.

[0058] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing silicon carbide ceramic welded parts resistant to hydrothermal corrosion and high-temperature oxidation, characterized in that, The specific steps include the following: S1. Al2O3, MgO, CaO, HfO2, Nd2O3 and SiO2 powders are ball-milled and mixed, and then water-quenched at 1600~1700℃ to obtain glass. After grinding and refining and sieving, glass powder is obtained; the mass ratio of Al2O3, MgO, CaO, HfO2, Nd2O3 and SiO2 is (15~20):(9~11):(8~10):(1~10):(1~6):(43~66). S2. The glass powder is dry-pressed at 1~100 MPa to obtain a glass preform. The glass block is placed in the welding area of ​​two SiC ceramics. Then the two SiC ceramics are placed according to the structure of the product to be formed to obtain the component to be connected. S3. The components to be joined are placed in a heating furnace and subjected to a mechanical pressure of 0.01~1MPa, and then heat-treated at 1350~1600 ℃ in a protective atmosphere to obtain silicon carbide ceramic welded parts. The thickness of the connecting layer of the silicon carbide ceramic welded parts is 1~50 μm, and the helium leakage rate of welded parts with a wall thickness of 0.5~5mm is 1.0×10⁻⁶. -12 ~1.0×10 -9 Pa·m 3 / s, the shear strength of the welded parts is 70~110 MPa. After static corrosion in pure water at 360℃ / 18.6 MPa / 7d in an autoclave, the single-sided dimension of the bonding layer degrades by 1~5 μm.

2. The method for preparing silicon carbide ceramic welded parts resistant to hydrothermal corrosion and high-temperature oxidation according to claim 1, characterized in that, The sieve in step S1 has a mesh size of 50-400 mesh, and the water quenching time is 0.5-2 hours.

3. The method for preparing silicon carbide ceramic welded parts resistant to hydrothermal corrosion and high-temperature oxidation according to claim 1, characterized in that, The dry pressing time in step S2 is 1~10 min; the thickness of the glass preform is 0.5~3 mm.

4. The method for preparing silicon carbide ceramic welded parts resistant to hydrothermal corrosion and high-temperature oxidation according to claim 1, characterized in that, The protective atmosphere mentioned in step S3 is one or more of nitrogen, helium or argon, and the pressure of the protective atmosphere is 0.1~0.5 MPa.

5. The method for preparing silicon carbide ceramic welded parts resistant to hydrothermal corrosion and high-temperature oxidation according to claim 1, characterized in that, The specific process of heat treatment in step S3 is as follows: heat up to 1000 ℃ at 1~10 ℃ / min, then heat up to 1350~1600 ℃ at 1~5 ℃ / min and hold for 5~60 min, then cool down to 1100 ℃ at 1~3 ℃ / min, then cool down to 400 ℃ at 1~5 ℃ / min and cool with the furnace.

6. A silicon carbide ceramic weldment resistant to hydrothermal corrosion and high-temperature oxidation, characterized in that, The silicon carbide ceramic weldment is prepared by the method described in any one of claims 1-5.

7. The application of the silicon carbide ceramic weldment resistant to hydrothermal corrosion and high-temperature oxidation as described in claim 6 in the field of high-temperature heat exchange or nuclear energy.

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