A thermal shielding component for a thermonuclear fusion reactor superconducting coil and a method for preparing the same

Abstract

The present invention belongs to the technical field of thermonuclear fusion reactors, and specifically relates to a thermal shielding component of a superconducting coil of a thermonuclear fusion reactor and a preparation method thereof, comprising: an F-type tube A, an F-type tube B, a copper plate A, a copper plate B, a copper plate C, and a copper-chromium-zirconium steel tube brazing assembly; the copper plate A3 and the copper plate B4 are connected via the copper-chromium-zirconium steel tube brazing assembly, and a copper-chromium-zirconium steel tube brazing assembly is arranged between the copper plate B and the copper plate C; and the F-type tube A and the F-type tube B are respectively arranged at both ends of the copper-chromium-zirconium steel tube brazing assembly.

Description

Technical Field

[0001] The invention belongs to the technical field of thermonuclear fusion reactors, and in particular relates to a superconducting coil heat shielding component of a thermonuclear fusion reactor and a preparation method thereof. Background Art

[0002] ITER is currently the world's largest superconducting tokamak device. In the ITER device, the magnetic confinement of plasma is achieved through different superconducting coils. The fusion reactor magnet system includes 18 correction coils, which must be kept below extremely low temperatures to maintain superconductivity and thus maintain the stable operation of the ITER device. However, each poloidal field coil box in contact with the correction field coil generates about 16.596kW of heat under the magnetic field. In order to ensure the normal operation of the correction field superconducting magnet during the operation of the fusion reactor. The heat shield component composed of a copper alloy plate in contact with the poloidal field coil support and a 316L pipe system with 10k and 5bar helium refrigerant inside is located between the poloidal field coil support and the correction coil clamp to take away the heat generated by the poloidal field coil support.

[0003] There are several problems with heat shield components at present:

[0004] 1) It is impossible to achieve high-quality connection of stainless steel pipe and copper plate vacuum brazing joints over a length of more than 1000 mm;

[0005] 2) The grains of copper alloy plates grow severely during vacuum brazing with steel pipes, resulting in degradation of mechanical properties. After brazing thermal cycles, the yield strength of copper is even lower than 60MPa.

[0006] 3) TS is a vacuum chamber component with a large number of welds, which requires it to have good sealing performance, and its leakage requirement is 1x10-9Pa.m3 / s;

[0007] Therefore, it is necessary to design a superconducting coil heat shielding component to solve the technical problems of poor connection quality of heterogeneous materials, degradation of mechanical properties, and low vacuum sealing performance of the superconducting coil heat shielding component in the above-mentioned prior art. Summary of the invention

[0008] The purpose of the present invention is to design a superconducting coil heat shielding component for a thermonuclear fusion reactor and a preparation method thereof, so as to solve the technical problems of poor connection quality of heterogeneous materials, degradation of mechanical properties and low vacuum sealing performance of superconducting coil heat shielding components in the prior art.

[0009] The technical solution of the present invention:

[0010] A thermal shielding component for a thermonuclear fusion reactor superconducting coil comprises: an F-type tube A1, an F-type tube B2, a copper plate A3, a copper plate B4, a copper plate C5, and a copper-chromium-zirconium steel tube brazing assembly 6; the copper plate A3 and the copper plate B4 are connected via the copper-chromium-zirconium steel tube brazing assembly 6, and the copper plate B4 and the copper plate C5 are provided with the copper-chromium-zirconium steel tube brazing assembly 6; the F-type tube A1 and the F-type tube B2 are provided at both ends of the copper-chromium-zirconium steel tube brazing assembly 6, respectively.

[0011] The copper-chromium-zirconium steel pipe brazing assembly 6 comprises: a copper-chromium-zirconium block 10, a brazing material 7, a filler groove 8 and a steel pipe 9;

[0012] The copper-chromium-zirconium block 10 is a strip-shaped "convex" structure as a whole. A copper alloy through hole is opened in the center of the copper-chromium-zirconium block 10. The steel pipe 9 is inserted into the copper alloy through hole. There is no contact between the steel pipe 9 and the copper alloy through hole and a gap is left. A filling groove 8 is provided on one side of the copper alloy through hole; the solder 7 is placed in the filling groove 8.

[0013] The straightness of the steel pipe 9 is 0.02 mm / 100 mm, the roundness of the steel pipe 9 is within 0.02 mm, and the material of the steel pipe 9 is stainless steel; the material of the solder 7 is AgCu28.

[0014] A thermonuclear fusion reactor superconducting coil heat shielding component as described in any one of the above, comprising the following steps:

[0015] Step 1: machining the surface treatment of the steel pipe 9 and the copper-chromium-zirconium block 10 before brazing;

[0016] Step 2: Pre-brazing assembly and vacuum brazing of the steel tube 9 and the copper-chromium-zirconium block 10;

[0017] Step 3: Place in vacuum brazing furnace for brazing;

[0018] Step 4: After processing, the copper-chromium-zirconium steel tube brazing assembly 6 is connected to the copper plate A3, copper plate B4, and copper plate C5 by stir friction welding.

[0019] Step 5: Connect the F-type tube A1 and the F-type tube B2 to the steel tube 9 in the copper-chromium-zirconium steel tube brazing assembly 6 by TIG welding;

[0020] Step 6: Perform nondestructive testing on the friction stir welds between the copper-chromium-zirconium steel tube brazing assembly 6 and the copper plates 3, 4, 5 in step 4;

[0021] Step 7: Perform water pressure testing on the copper-chromium-zirconium alloy block 10 after welding in step 5, and perform vacuum positive pressure helium leak detection on the heat shielding component connected by TIG welding in step 5.

[0022] The step one also includes: the copper alloy through hole and straightness deviation on the copper-chromium-zirconium block 11 are within 0.02mm / 100mm; using anhydrous ethanol to ultrasonically clean the inner and outer surfaces of the steel pipe 9 and the copper-chromium-zirconium block 10, ensuring that the nickel plating layer is not damaged during the cleaning process, and then blowing it dry with hot nitrogen for later use.

[0023] The step 2 also includes:

[0024] Insert the nickel-plated steel tube 9 into the copper alloy through hole of the copper-chromium-zirconium alloy block 10; control the brazing gap between the steel tube 10 and the copper alloy through hole to be 0.03 mm; then insert the wire-shaped brazing material 7 into the filler groove 8 on the copper-chromium-zirconium alloy block 10 to form a copper-chromium-zirconium steel tube brazing assembly 6;

[0025] The step three also includes: placing the copper-chromium-zirconium steel tube brazing assembly 6 in step two into a vacuum furnace, setting the vacuum furnace brazing temperature to 8×10-3Pa, brazing at 800°C for 30 minutes, and then cooling to 500°C in the vacuum furnace; when the workpiece temperature drops to 500°C, accelerating cooling to 150°C at a rate of 5°C / min by introducing nitrogen.

[0026] The step four also includes: welding and connecting the longest sides of copper plate A3 and copper plate B4 through a copper-chromium-zirconium steel tube brazing assembly 6 by using a stir friction welding method, and similarly welding and connecting the other longest side of copper plate B4 and one longest side of copper plate C5 through a copper-chromium-zirconium steel tube brazing assembly 6 by using a stir friction welding method; welding parameter range: welding speed v=100mm / min, rotation speed U is 500rpm, and stirring head pressure is 1000N.

[0027] The step five also includes: the TIG welding process parameters are current 88A, voltage 10V, and welding speed 10° / s.

[0028] The step six also includes: using 120° projection, double-wall double-shadow radiographic flaw detection three times to check the weld quality of the brazed joint, and the weld shall not have surface defects exceeding 1 mm; using 120° projection, double-wall double-shadow radiographic flaw detection three times to check the weld quality of the steel pipe 10 joint, and the weld shall not have defects exceeding 0.4 mm; using vertical transmission flaw detection to check the weld quality of the stir friction weld between the copper-chromium-zirconium steel pipe brazing assembly 6 and the copper plates 3, 4, and 5, and there shall be no defects exceeding 0.4 mm.

[0029] The step 7 of performing a water pressure test on the copper-chromium-zirconium block 10 welded in step 5 includes: setting the water pressure test pressure to 5±0.2MPa, testing the water pressure for 30min, and detecting the copper-chromium-zirconium block 10 for leakage and visible permanent deformation when the pressure value change is less than 0.2MPa;

[0030] The step 7 of performing vacuum positive pressure helium leak detection on the heat shielding component welded in step 5 comprises: placing the heat shielding component welded in step 5 into a vacuum chamber, and pumping the vacuum degree in the vacuum chamber to 1×10 -4 Pa, fill the heat shielding component with 3MPa helium and maintain the pressure for 30min. The leakage rate of the copper-chromium-zirconium block 10 should be lower than 1×10-9Pa.m 3 / s.

[0031] Beneficial effects of the present invention:

[0032] 1) The present invention uses a high-precision deep hole drill to process the copper tube, which effectively ensures the brazing gap between the copper block and the steel tube lap joint, and the brazing rate can reach more than 95%;

[0033] 2) The present invention cools the steel pipe to liquid nitrogen temperature and then inserts it into the copper block, which can further control the brazing gap compared with the traditional method, so that the shear strength of the steel-copper brazing joint can reach more than 210MPa;

[0034] 3) The present invention realizes a 360° connection with the inner hole of the copper in the circumferential direction of the steel pipe, and the thermal conductivity of the component can be greatly improved by using a silver-based solder with high thermal conductivity;

[0035] 4) The present invention uses a small amount of copper-chromium-zirconium block to braze the tube to form a steel tube & copper block brazing assembly, and then stir friction welding is used to connect the copper-chromium-zirconium on the brazing assembly and the large area copper plate at room temperature, which can avoid the degradation of the copper plate such as coarsening of the grain size and reduction of mechanical properties during brazing;

[0036] 5) The present invention uses a small amount of copper-chromium-zirconium blocks to braze and connect with high-temperature resistant stainless steel pipes to form a steel pipe & copper block brazing assembly, and then stir friction welding is used to connect the copper-chromium-zirconium on the brazing assembly and the large area of ​​copper plate at room temperature, which is not only beneficial to quality control but also improves production efficiency;

[0037] 6) The present invention uses friction stir welding to connect copper-chromium-zirconium and large-area copper plates on brazed components. Due to the inherent properties of low heat input semi-solid connection of friction stir welding, the welding deformation of the components can be effectively reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic structural diagram of the thermal shielding component of the superconducting coil of the thermonuclear fusion reactor described in the present invention;

[0039] Figure 2 A schematic cross-sectional view of the copper-chromium-zirconium block described in the present invention

[0040] Among them, 1-F type tube A; 2-F type tube B, 3-copper plate A; 4-copper plate B, 5-copper plate C, 6-copper-chromium-zirconium steel tube brazing assembly; 7-brazing filler metal, 8-filling tank, 9-steel tube, 10-copper-chromium-zirconium block; DETAILED DESCRIPTION

[0041] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0042] A thermal shielding component for a superconducting coil of a thermonuclear fusion reactor comprises: an F-type tube A1, an F-type tube B2, a copper plate A3, a copper plate B4, a copper plate C5, and a copper-chromium-zirconium steel tube brazing assembly 6; the copper plate A3 and the copper plate B4 are connected via the copper-chromium-zirconium steel tube brazing assembly 6, and the copper plate B4 and the copper plate C5 are provided with the copper-chromium-zirconium steel tube brazing assembly 6; the F-type tube A1 and the F-type tube B2 are provided at both ends of the copper-chromium-zirconium steel tube brazing assembly A6, respectively.

[0043] The copper-chromium-zirconium steel pipe brazing assembly 6 comprises: a copper-chromium-zirconium block 10, a brazing material 7, a filler groove 8 and a steel pipe 9;

[0044] The copper-chromium-zirconium block 10 is a strip-shaped "convex" structure as a whole. A copper alloy through hole is opened in the center of the copper-chromium-zirconium block 10. The steel pipe 9 is inserted into the copper alloy through hole. There is no contact between the steel pipe 9 and the copper alloy through hole and a gap is left. A filling groove 8 is provided on one side of the copper alloy through hole; the solder 7 is placed in the filling groove 8.

[0045] The straightness of the steel pipe 9 is 0.02 mm / 100 mm, the roundness of the steel pipe 9 is within 0.02 mm, and the material of the steel pipe 9 is stainless steel; the material of the solder 7 is AgCu28.

[0046] A thermonuclear fusion reactor superconducting coil heat shielding component as described in any one of the above, comprising the following steps:

[0047] Step 1: machining the surface treatment of the steel pipe 9 and the copper-chromium-zirconium block 10 before brazing;

[0048] Step 2: Pre-brazing assembly and vacuum brazing of the steel tube 9 and the copper-chromium-zirconium block 10;

[0049] Step 3: Place in vacuum brazing furnace for brazing;

[0050] Step 4: Heat the copper-chromium-zirconium steel tube brazing assembly 6 and connect it with the copper plates A3, B4 and C5 by friction stir welding.

[0051] Step 5: Connect the F-type tube A1 and the F-type tube B2 to the steel tube 9 in the copper-chromium-zirconium steel tube brazing assembly 6 by TIG welding;

[0052] Step 6: Perform nondestructive testing on the friction stir welds between the copper-chromium-zirconium steel tube brazing assembly 6 and the copper plates 3, 4, 5;

[0053] Step 7: Perform water pressure testing on the copper-chromium-zirconium alloy block 10 after welding in step 5, and perform vacuum positive pressure helium leak detection on the heat shielding component connected by TIG welding in step 5.

[0054] The step one also includes: the copper alloy through hole and straightness deviation on the copper-chromium-zirconium block 11 are within 0.02mm / 100mm; using anhydrous ethanol to ultrasonically clean the inner and outer surfaces of the steel pipe 9 and the copper-chromium-zirconium block 10, ensuring that the nickel plating layer is not damaged during the cleaning process, and then blowing it dry with hot nitrogen for later use.

[0055] The step 2 also includes:

[0056] Insert the nickel-plated steel tube 9 into the copper alloy through hole of the copper-chromium-zirconium alloy block 10; control the brazing gap between the steel tube 10 and the copper alloy through hole to be 0.03 mm; then insert the wire-shaped brazing material 7 into the filler groove 8 on the copper-chromium-zirconium alloy block 10 to form a copper-chromium-zirconium steel tube brazing assembly 6;

[0057] The step three also includes: placing the copper-chromium-zirconium steel tube brazing assembly 6 in step two into a vacuum furnace, setting the vacuum furnace brazing temperature to 8×10-3Pa, brazing at 800°C for 30 minutes, and then cooling to 500°C in the vacuum furnace; when the workpiece temperature drops to 500°C, accelerating cooling to 150°C at a rate of 5°C / min by introducing nitrogen.

[0058] The step four also includes: welding and connecting the longest sides of copper plate A3 and copper plate B4 through a copper-chromium-zirconium steel tube brazing assembly 6 by using a stir friction welding method, and similarly welding and connecting the other longest side of copper plate B4 and one longest side of copper plate C5 through a copper-chromium-zirconium steel tube brazing assembly 6 by using a stir friction welding method; welding parameter range: welding speed v=100mm / min, rotation speed U is 500rpm, and stirring head pressure is 1000N.

[0059] The step five also includes: the TIG welding process parameters are current 88A, voltage 10V, and welding speed 10° / s.

[0060] The step six also includes: using 120° projection, double-wall double-shadow radiographic flaw detection three times to check the weld quality of the brazed joint, and the weld shall not have surface defects exceeding 1 mm; using 120° projection, double-wall double-shadow radiographic flaw detection three times to check the weld quality of the steel pipe 10 joint, and the weld shall not have defects exceeding 0.4 mm; using vertical transmission flaw detection to check the weld quality of the stir friction weld between the copper-chromium-zirconium steel pipe brazing assembly 6 and the copper plates 3, 4, and 5, and there shall be no defects exceeding 0.4 mm.

[0061] The step 7 of performing a water pressure test on the copper-chromium-zirconium block 10 welded in step 5 includes: setting the water pressure test pressure to 5±0.2MPa, testing the water pressure for 30min, and detecting the copper-chromium-zirconium block 10 for leakage and visible permanent deformation when the pressure value change is less than 0.2MPa;

[0062] The step 7 of performing vacuum positive pressure helium leak detection on the heat shielding component welded in step 5 comprises: placing the heat shielding component welded in step 5 into a vacuum chamber, and pumping the vacuum degree in the vacuum chamber to 1×10 -4 Pa, fill the heat shielding component with 3MPa helium and maintain the pressure for 30min. The leakage rate of the copper-chromium-zirconium block 10 should be lower than 1×10-9Pa.m 3 / s.

[0063] The present invention is described in detail above with reference to the accompanying drawings and embodiments, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the field without departing from the purpose of the present invention. Any content not described in detail in the present invention can adopt the existing technology.

Claims

1. A thermal shielding component for a superconducting coil of a thermonuclear fusion reactor, characterized in that: include: F-type tube A (1), F-type tube B (2), copper plate A (3), copper plate B (4), copper plate C (5), copper-chromium-zirconium steel tube brazing assembly (6); the copper plate A (3) and copper plate B (4) are connected via the copper-chromium-zirconium steel tube brazing assembly (6), and the copper plate B (4) and copper plate C (5) are provided with the copper-chromium-zirconium steel tube brazing assembly (6); the F-type tube A (1) and the F-type tube B (2) are provided at both ends of the copper-chromium-zirconium steel tube brazing assembly (6); The copper-chromium-zirconium steel pipe brazing assembly (6) comprises: a copper-chromium-zirconium block (10), a brazing filler metal (7), a filler groove (8) and a steel pipe (9); The copper-chromium-zirconium block (10) is a strip-shaped "convex" structure as a whole. A copper alloy through hole is opened in the center of the copper-chromium-zirconium block (10). The steel pipe (9) is inserted into the copper alloy through hole. The steel pipe (9) and the copper alloy through hole are not in contact and a gap is left. A filling groove (8) is provided on one side of the copper alloy through hole. The brazing material (7) is placed in the filling groove (8); The straightness of the steel pipe (9) is 0.02 mm / 100 mm, the roundness of the steel pipe (9) is within 0.02 mm, and the material of the steel pipe (9) is stainless steel; the material of the solder (7) is AgCu28.

2. A method for preparing a thermal shielding component of a thermonuclear fusion reactor superconducting coil as claimed in claim 1, characterized in that: The steps include: Step 1: machining the surface treatment of the steel pipe (9) and the copper-chromium-zirconium block (10) before brazing; Step 2: pre-brazing assembly and vacuum brazing of the steel pipe (9) and the copper-chromium-zirconium block (10); Step 3: Place in vacuum brazing furnace for brazing; Step 4: After processing, the copper-chromium-zirconium steel tube brazing assembly (6) is connected to the copper plate A (3), copper plate B (4), and copper plate C (5) by stir friction welding. Step 5: Using TIG welding, connect the F-type tube A (1) and the F-type tube B (2) to the steel tube (9) in the copper-chromium-zirconium steel tube brazing assembly (6); Step 6: Perform nondestructive testing on the friction stir welds between the copper-chromium-zirconium steel tube brazing assembly (6) and the copper plate A (3), copper plate B (4), and copper plate C (5) in step 4; Step 7: Performing a water pressure test on the copper-chromium-zirconium block (10) welded in step 5; and performing a vacuum positive pressure helium leak test on the heat shielding component connected by TIG welding in step 5.

3. The method for preparing a thermal shielding component of a thermonuclear fusion reactor superconducting coil according to claim 2, characterized in that: The step one also includes: the copper alloy through hole and straightness deviation on the copper-chromium-zirconium block (10) are within 0.02 mm / 100 mm; using anhydrous ethanol to ultrasonically clean the inner and outer surfaces of the steel pipe (9) and the copper-chromium-zirconium block (10), ensuring that the nickel plating layer is not damaged during the cleaning process, and then blowing it dry with hot nitrogen for later use.

4. The method for preparing a thermal shielding component of a thermonuclear fusion reactor superconducting coil according to claim 3, characterized in that: The step 2 also includes: Insert the nickel-plated steel tube (9) into the copper alloy through hole of the copper-chromium-zirconium block (10); control the brazing gap between the steel tube (9) and the copper alloy through hole to be 0.03 mm; then insert the wire-shaped brazing material (7) into the filler groove (8) on the copper-chromium-zirconium block (10) to form a copper-chromium-zirconium steel tube brazing assembly (6).

5. The method for preparing a thermal shielding component of a thermonuclear fusion reactor superconducting coil according to claim 4, characterized in that: The step three also includes: placing the copper-chromium-zirconium steel tube brazing assembly (6) in the step two into a vacuum furnace, setting the vacuum furnace brazing temperature to 8×10-3 Pa, brazing at 800° C. for 30 minutes, and then cooling to 500° C. in the vacuum furnace; when the workpiece temperature drops to 500° C., accelerating cooling to 150° C. at a rate of 5° C. / min by introducing nitrogen.

6. The method for preparing a thermal shielding component of a thermonuclear fusion reactor superconducting coil according to claim 5, characterized in that: The step 4 further comprises: welding and connecting the longest sides of the copper plate A (3) and the copper plate B (4) by means of a copper-chromium-zirconium steel tube brazing assembly (6) using a stir friction welding method, and similarly welding and connecting the other longest side of the copper plate B (4) and the longest side of the copper plate C (5) by means of a copper-chromium-zirconium steel tube brazing assembly (6) using a stir friction welding method; welding parameter range: welding speed v=100 mm / min, rotation speed U is 500 rpm, and stirring head pressure is 1000N.

7. The method for preparing a thermal shielding component of a thermonuclear fusion reactor superconducting coil according to claim 6, characterized in that: The step five also includes: the TIG welding process parameters are current 88A, voltage 10V, and welding speed 10° / s.

8. The method for preparing a thermal shielding component of a thermonuclear fusion reactor superconducting coil according to claim 7, characterized in that: The step six also includes: using 120° projection, double-wall double-shadow radiographic flaw detection three times to check the weld quality of the brazed joint, and the weld shall not have surface defects exceeding 1 mm; using 120° projection, double-wall double-shadow radiographic flaw detection three times to check the weld quality of the steel pipe (9) joint, and the weld shall not have defects exceeding 0.4 mm; using vertical transmission flaw detection to check the weld quality of the stir friction weld between the copper-chromium-zirconium steel pipe brazed assembly (6) and the copper plate A (3), copper plate B (4), and copper plate C (5), and the weld shall not have defects exceeding 0.4 mm.

9. The method for preparing a thermal shielding component of a thermonuclear fusion reactor superconducting coil according to claim 8, characterized in that: The step 7 of performing a water pressure test on the copper-chromium-zirconium block (10) welded in step 5 comprises: setting the water pressure test pressure to 5±0.2 MPa, testing the water pressure for 30 minutes, and detecting leakage and visible permanent deformation of the copper-chromium-zirconium block (10) when the pressure value changes less than 0.2 MPa; The step 7 of performing vacuum positive pressure helium leak detection on the heat shielding component welded by TIG in step 5 comprises: placing the heat shielding component welded by step 5 into a vacuum chamber, and pumping the vacuum degree in the vacuum chamber to 1×10 -4 Pa, fill the heat shield with 3MPa helium and maintain the pressure for 30min. The leakage rate of the copper-chromium-zirconium block (10) should be lower than 1×10 -9 Pa.m 3 / s.

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