A Welding Method for a Platinum / Niobium Composite Plate and a Niobium Screw

Abstract

The present invention discloses a welding method for a platinum / niobium composite plate and a niobium screw. This method uses a water-cooled copper tooling with a pressing device to reduce the thermal deformation of the composite plate; selects a low-melting-point titanium alloy wire that can be mutually melted with niobium metal as the filler wire to reduce the temperature of the welding molten pool; and adopts intermittent welding, welding multiple times repeatedly until the entire circumference is welded full. The welding method of the platinum / niobium composite anode plate and the niobium screw of the present invention solves the technical problems that when the existing platinum / niobium composite anode plate and the niobium screw are welded, the temperature is too high, resulting in deformation of the composite plate, peeling or melting failure of the platinum coating layer.

Description

Technical Field

[0001] The present invention belongs to the technical field of welding, and particularly relates to a welding method for a platinum / niobium composite plate and a niobium screw. Background Art

[0002] The impressed current cathodic protection method is one of the electro-chemical protection methods. Electro-chemical protection is divided into cathodic protection method and anodic protection method. Among them, the cathodic protection method is further divided into sacrificial anode protection method and impressed current protection method. This method forces electrons to flow to the metal to be protected through an external DC power supply and an auxiliary anode, making the potential of the metal structure to be protected higher than the surrounding environment for protection. Ships generally often use this method to protect the hull from seawater corrosion. The impressed current cathodic protection system outside the ship generally consists of a potentiostat, an auxiliary anode, an anode shielding layer, a reference electrode, a main shaft grounding and a rudder grounding device, etc. The role of the auxiliary anode is to transfer the protection current to the hull surface through seawater, replacing the hull for electro-chemical corrosion. Aluminum is generally used as the anode for hull anti-corrosion to protect the hull. However, since an oxide film will be formed on the surface during the corrosion process of aluminum, a passivation reaction will occur, preventing the flow of electrons to the steel hull, so it is difficult to play a role in protecting the steel hull.

[0003] At the present stage, the commonly used auxiliary anode is a platinum / niobium composite anode. First, a platinum coating is prepared on the surface of the niobium plate, and then the platinum / niobium composite plate with the platinum coating is connected to the niobium screw by welding to make a platinum / niobium auxiliary anode. The structure of the platinum / niobium auxiliary anode is as Figure 1 shown. However, the commonly used welding method will generate a large amount of heat during the welding process, and the heat will cause the failure of the platinum coating and the warping deformation of the composite plate. Therefore, in view of the above technical problems, it is necessary to invent a new and low-temperature welding method to ensure the formability and integrity of the composite plate and the platinum coating during the welding process. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a welding method for a platinum / niobium composite plate and a niobium screw in view of the deficiencies in the above-mentioned prior art. This method uses a niobium screw and a platinum / niobium composite plate as raw materials, uses a low-melting-point titanium alloy wire that can be mutually melted with metallic niobium as the welding wire, and welds the platinum / niobium composite plate and the niobium screw through repeated spot welding. The welding process is protected by an inert gas, reducing the risk of oxidation of the composite plate and the niobium screw during the welding process, and is equipped with a water-cooled copper tooling to further reduce the temperature at the welding joint of the welded part during the welding process.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is: a welding method for a platinum / niobium composite plate and a niobium screw, characterized in that the platinum / niobium composite plate includes a niobium plate and a platinum coating attached to the niobium plate, and the welding method includes the following steps:

[0006] Step 1: Machine a positioning hole at the center of the niobium plate, and clean the surfaces of the niobium screw and the platinum / niobium composite plate with a positioning hole.

[0007] Step 2: Assemble the platinum / niobium composite plate cleaned in Step 1 on a water-cooled copper tooling with a pressing device, and adjust the pressing device to ensure that the platinum / niobium composite plate is in a horizontal state.

[0008] Step 3: Pass cooling water through the water-cooled copper tooling, insert the niobium screw cleaned in Step 1 into the positioning hole, and make the niobium screw perpendicular to the surface of the platinum / niobium composite plate. Use a low-melting-point titanium alloy wire that can be mutually melted with niobium as the filler wire to perform the first point positioning welding on the end of the niobium screw and the platinum / niobium composite plate. Use a protective cover filled with inert gas to protect the first welding point. After the welding point cools to below 100°C in the protective gas, perform the second point positioning welding on the opposite side of the first positioning point.

[0009] Step 4: Adjust the welding current, control the molten pool depth and width within the minimum range, and use an intermittent welding process to weld the niobium screw and the platinum / niobium composite plate after the positioning welding in Step 3.

[0010] In the above welding method of a platinum / niobium composite plate and a niobium screw, it is characterized in that in Step 1, the thickness of the platinum / niobium composite plate is 1 mm to 5 mm, the width is 40 mm to 80 mm, and the length is 300 mm to 1000 mm; the thickness of the platinum coating is 0.02 mm to 0.05 mm, and the size of the niobium screw is Ф(12 - 15) mm × 180 mm. The diameter of the positioning hole is matched with the diameter of the welded niobium screw, and the depth of the positioning hole is 0.2 mm to 0.5 mm.

[0011] In the above welding method of a platinum / niobium composite plate and a niobium screw, it is characterized in that in Step 2, the water-cooled copper tooling with a pressing device includes an external frame, a cooling copper mold arranged in the middle of the external frame, a composite plate pressing plate and a sealing pressing strip detachably installed on the external frame. A columnar cooling water tank is opened in the center of the cooling copper mold. The cooling water tank is open, and a sealing ring is arranged at the opening of the cooling water tank. Cooling water interfaces are arranged on the front side and the rear side of the cooling water tank.

[0012] In the above welding method of a platinum / niobium composite plate and a niobium screw, it is characterized in that in Step 3, the material of the titanium alloy wire is TA1, TA2, TA3, TA4, TC4 or TC26, and the diameter of the filler wire is Ф1 mm to Ф3 mm.

[0013] In the above welding method of a platinum / niobium composite plate and a niobium screw, it is characterized in that in Step 3, the cooling water flow rate in the water-cooled copper tooling is 1 L / min to 20 L / min, and in Step 2, the pressing force of the pressing device is 0.1 KN to 3 KN.

[0014] The above-mentioned welding method for a platinum / niobium composite plate and a niobium screw is characterized in that the mass purity of the inert gas in step three is ≥99.99%.

[0015] The above-mentioned welding method for a platinum / niobium composite plate and a niobium screw is characterized in that the welding current in step four is 200 A to 280 A;

[0016] The above-mentioned welding method for a platinum / niobium composite plate and a niobium screw is characterized in that the intermittent welding process in step four specifically includes: during welding, after one or two drops of the welding wire are melted, the welding is stopped, and after the molten pool cools in the inert gas, the next point of welding is carried out. The welding is repeated multiple times until a full circle is welded.

[0017] The above-mentioned welding method for a platinum / niobium composite plate and a niobium screw is characterized in that the mass purity of the inert gas is ≥99.99%.

[0018] The present invention has the following advantages compared with the prior art:

[0019] 1. On the basis of the previous welding of platinum / niobium composite plates and niobium screws, the present invention uses a low-melting-point titanium alloy wire that can be mutually melted with niobium metal instead of niobium as the welding wire, reducing the temperature of the molten pool, so that the welding current is reduced to 200 A to 280 A, solving the technical problem that the composite plate is deformed, the platinum coating is peeled off or melted and fails due to excessive temperature during the welding of the existing platinum / niobium composite anode plate and the niobium screw.

[0020] 2. The present invention adopts a water-cooled copper tooling with a pressing device. The cooling water tank in the cooling copper mold at the core of the tooling can make the cooling water directly contact the platinum coating of the composite plate during welding, and can quickly cool the platinum composite layer. When the cooling water flow rate is 20 L / min and the pressing force of the pressing device is 3 KN, the weldable thickness of the platinum / niobium composite plate will be greatly reduced to 1.0 mm.

[0021] The following combines the drawings and embodiments to make a further detailed description of the technical solution of the present invention. Description of the Drawings

[0022] Figure 1 It is a schematic structural diagram of the platinum / niobium composite plate after processing the positioning holes of the present invention.

[0023] Figure 2 It is a schematic structural diagram of the assembly of the platinum / niobium composite plate and the niobium screw of the present invention.

[0024] Figure 3 It is a schematic structural diagram of the water-cooled copper tooling with a pressing device assembled with the platinum / niobium composite plate and the niobium screw of the present invention.

[0025] Figure 4 is Figure 3Top view.

[0026] Figure 5 Is the physical drawing prepared by welding in Example 2 of the present invention.

[0027] Figure 6 Is the physical drawing prepared by welding in Comparative Example 1.

[0028] Figure 7 Is the physical drawing prepared by welding in Comparative Example 2.

[0029] Explanation of reference numerals:

[0030] 1 - Platinum coating; 2 - Niobium plate; 3 - Positioning hole;

[0031] 4 - Niobium screw; 5 - Outer frame; 6 - Cooling copper mold;

[0032] 7 - Cooling water tank; 8 - Sealing ring; 9 - Composite plate pressing plate;

[0033] 10 - Sealing and pressing strip; 11 - Cooling water interface. Detailed implementation manners

[0034] Example 1

[0035] As Figure 3 And Figure 4 Shown, the water-cooled copper tooling with a pressing device adopted by the present invention includes an outer frame 5 made of low-cost materials such as aluminum and iron to reduce costs, a cooling copper mold 6 arranged in the middle of the outer frame 5, a composite plate pressing plate 9 and a sealing and pressing strip 10 detachably installed on the outer frame 5. A columnar cooling water tank 7 is opened in the center of the cooling copper mold 6. The cooling water tank 7 is open, so that the cooling water can directly contact the platinum coating 1 of the composite plate during welding. A sealing ring 8 is arranged at the opening of the cooling water tank 7 to prevent the cooling water from overflowing. Cooling water interfaces 11 are arranged on the front side and the rear side of the cooling water tank 7 to make the cooling water circulate and quickly cool the platinum composite layer 1.

[0036] Example 2

[0037] The welding method of the platinum / niobium composite plate and the niobium screw in this example. The platinum / niobium composite plate includes a niobium plate 2 and a platinum coating 1 attached to the niobium plate 2. The thickness of the niobium plate 2 of the platinum / niobium composite plate is 3 mm, the width is 60 mm, and the length is 500 mm; the thickness of the platinum coating 1 is 0.02 mm, and the size of the niobium screw 4 is Ф12 mm × 180 mm. The diameter of the positioning hole 3 is matched with the diameter of the welded niobium screw, and the depth of the positioning hole 3 is 0.2 mm; the welding method includes the following steps:

[0038] Step 1. As Figure 1 And Figure 2As shown in the figure, a positioning hole 3 with a diameter of Ф12mm is machined at the center of the niobium plate 2, and the surfaces of the niobium screw 4 and the platinum / niobium composite plate with a positioning hole are cleaned up.

[0039] Step 2: Place the platinum-coated layer 1 of the platinum / niobium composite plate cleaned in Step 1 downward and assemble it on the water-cooled copper tooling with a pressing device, so that the platinum-coated layer 1 is pressed at the center of the sealing ring 8 of the cooling water tank 7. Fix the composite plate pressing plate 9 and the sealing pressing strip 10, and make the pressing force 0.1KN to ensure that the platinum / niobium composite plate is in a horizontal state. There is a fixing screw on the composite plate pressing plate 9. When replacing the platinum / niobium composite plate, loosen the fixing screw, and the composite plate pressing plate 9 can be rotated to the edge of the tooling, which is convenient for disassembly and use. When fixing and replacing the platinum / niobium composite plate, the sealing pressing strip 10 can also be rotated to the edge of the tooling.

[0040] Step 3: Pass cooling water into the cooling water tank 7 of the water-cooled copper tooling through the cooling water interface 11, and the cooling water flow rate is 1L / min. Insert the niobium screw 4 cleaned in Step 1 into the positioning hole 3, and make the niobium screw 4 perpendicular to the surface of the platinum / niobium composite plate. Use a TA1 titanium alloy wire with a diameter of Ф1mm and a clean and pollution-free surface as the filler wire, and use an argon arc welding gun to perform the first point positioning welding on the end of the niobium screw 4 and the platinum / niobium composite plate. Use a protective cover filled with an inert gas with a mass purity ≥99.99% to protect the first welding point. After the welding point cools to below 100°C in the protective gas, perform the second point positioning welding on the opposite side of the first positioning point with an argon arc welding gun.

[0041] Step 4: Adjust the welding current to 200A, control the molten pool depth and width within the minimum range, and use an intermittent welding process to weld the niobium screw and the platinum / niobium composite plate after the positioning welding in Step 3. That is, during welding, stop welding after one or two drops of the filler wire melt, and wait for the molten pool to cool in the inert gas before performing the next point welding. Repeat the welding multiple times until the entire circumference is welded. The mass purity of the inert gas ≥99.99%.

[0042] Figure 5 This is the physical drawing prepared by welding in this embodiment. It can be seen from the figure that after welding, the platinum-coated layer is intact and the composite plate does not warp or deform.

[0043] Comparative Example 1

[0044] Step 1: Open a blind hole with a diameter of Ф12mm at the center of the niobium side of the platinum / niobium composite plate as the positioning hole, and clean up the surfaces of the niobium screw with a size of Ф12mm×180mm and the platinum / niobium composite plate with a positioning hole. The thickness of the niobium plate of the platinum / niobium composite plate is 3mm, the width is 60mm, the length is 500mm, and the thickness of the platinum-coated layer is 0.02mm.

[0045] Step 2: Install the niobium screw cleaned in Step 1 into the positioning hole, assemble it with the platinum / niobium composite plate on the water-cooled copper tooling with a pressing device, adjust the pressing device to ensure that the platinum / niobium composite plate is in a horizontal state, and make the niobium screw perpendicular to the surface of the platinum / niobium composite plate;

[0046] Step 3: Pass cooling water through the water-cooled copper tooling. Use pure niobium wire with a diameter of Ф1mm and a clean and pollution-free surface as the filler wire to perform the first spot welding on the end of the niobium screw and the platinum / niobium composite plate. Use a protective cover filled with inert gas to protect the first weld point. After the weld point cools to 80°C in the protective gas, perform the second spot welding on the opposite side of the first positioning point; the cooling water flow rate in the water-cooled copper tooling is 1L / min, and the pressing force of the pressing device is 0.1KN; the mass purity of the inert gas ≥99.99%;

[0047] Step 4: Adjust the welding current to 320A, control the molten pool depth and width within the minimum range, and use an intermittent welding process to weld the niobium screw and the platinum / niobium composite plate after spot welding in Step 3, that is, during welding, stop welding after one or two drops of the filler wire melt, and wait for the molten pool to cool in the inert gas before performing the next welding point. Repeat the welding multiple times until the entire circumference is welded. The mass purity of the inert gas ≥99.99%.

[0048] Figure 6 The physical drawing prepared by welding in Comparative Example 1. Since pure niobium wire is used as the filler wire, the welding current is large and the welding temperature is high. Although a water-cooled copper tooling is used, black failure points appear on the platinum coating after welding.

[0049] Example 3

[0050] The welding method of the platinum / niobium composite plate and the niobium screw in this example. The platinum / niobium composite plate includes a niobium plate 2 and a platinum coating 1 attached to the niobium plate 2. The thickness of the niobium plate 2 of the platinum / niobium composite plate is 1mm, the width is 60mm, and the length is 300mm; the thickness of the platinum coating 1 is 0.05mm, and the size of the niobium screw 4 is Ф15mm×180mm. The diameter of the positioning hole 3 is matched with the diameter of the welded niobium screw, and the depth of the positioning hole 3 is 0.3mm; the welding method includes the following steps:

[0051] Step 1: As shown in Figure 1 and Figure 2 , machine a Ф15mm positioning hole 3 at the center position of the niobium plate 2, and clean the surfaces of the niobium screw 4 and the platinum / niobium composite plate with the positioning hole;

[0052] Step 2: Place the platinum cladding 1 of the platinum / niobium composite plate cleaned in Step 1 downward and assemble it on the water-cooled copper tooling with a pressing device, so that the platinum cladding 1 is pressed at the center of the sealing ring 8 of the cooling water tank 7. Fix the composite plate pressing plate 9 and the sealing pressing strip 10, and make the pressing force 3 KN to ensure that the platinum / niobium composite plate is in a horizontal state. There is a fixing screw on the composite plate pressing plate 9. When replacing the platinum / niobium composite plate, loosen the fixing screw, and the composite plate pressing plate 9 can be rotated to the edge of the tooling for convenient disassembly and use. When fixing and replacing the platinum / niobium composite plate, the sealing pressing strip 10 can also be rotated to the edge of the tooling;

[0053] Step 3: Pass cooling water into the cooling water tank 7 of the water-cooled copper tooling through the cooling water interface 11, with a cooling water flow rate of 20 L / min. Insert the niobium screw 4 cleaned in Step 1 into the positioning hole 3, and make the niobium screw 4 perpendicular to the surface of the platinum / niobium composite plate. Use a TC26 titanium alloy wire with a diameter of Ф3 mm and a clean and pollution-free surface as the filler wire, and use a TIG welding torch to perform the first point positioning welding on the end of the niobium screw 4 and the platinum / niobium composite plate. Use a protective cover filled with an inert gas with a mass purity ≥ 99.99% to protect the first weld point. After the weld point cools to 25°C in the protective gas, perform the second point positioning welding on the opposite side of the first positioning point using a TIG welding torch;

[0054] Step 4: Adjust the welding current to 280 A, control the molten pool depth and width within the minimum range, and use an intermittent welding process to weld the niobium screw and the platinum / niobium composite plate after the positioning welding in Step 3. That is, during welding, stop welding after one or two drops of the filler wire melt. Wait for the molten pool to cool in the inert gas and then perform the next point welding. Repeat the welding multiple times until the entire circumference is welded. The mass purity of the inert gas ≥ 99.99%.

[0055] After welding in this embodiment, the platinum cladding is intact and the composite plate does not warp or deform.

[0056] Comparative Example 2

[0057] Step 1: Drill a blind hole with a diameter of Ф15 mm in the center of the niobium side of the platinum / niobium composite plate as the positioning hole, and clean the surfaces of the niobium screw with a size of Ф15 mm × 180 mm and the platinum / niobium composite plate with the positioning hole; the niobium plate thickness of the platinum / niobium composite plate is 1 mm, the width is 60 mm, the length is 300 mm, and the platinum cladding thickness is 0.05 mm;

[0058] Step 2: Use a TC26 titanium alloy wire with a diameter of Ф3 mm and a clean and pollution-free surface as the filler wire to perform the first point positioning welding on the end of the niobium screw and the platinum / niobium composite plate. Use a protective cover filled with an inert gas to protect the first weld point. After the weld point cools to 25°C in the protective gas, perform the second point positioning welding on the opposite side of the first positioning point; the mass purity of the inert gas ≥ 99.99%;

[0059] Step 3: Adjust the welding current to 280 A, control the depth and width of the molten pool within the minimum range, and use the intermittent welding process to weld the niobium screw and the platinum / niobium composite plate after tack welding in Step 2. That is, during welding, stop welding after one or two drops of the welding wire are melted. Wait for the molten pool to cool in the inert gas and then perform the next welding point. Repeat the welding multiple times until a full circle is welded. The mass purity of the inert gas is ≥99.99%.

[0060] Figure 7 Fig. 5 is a physical drawing of the product prepared by welding in Comparative Example 2. Since the water-cooled copper tooling was not used, the platinum / niobium composite plate warped and deformed after welding.

[0061] Example 4

[0062] The welding method of the platinum / niobium composite plate and the niobium screw in this example. The platinum / niobium composite plate includes a niobium plate 2 and a platinum coating 1 attached to the niobium plate 2. The thickness of the niobium plate 2 of the platinum / niobium composite plate is 5 mm, the width is 40 mm, and the length is 1000 mm. The thickness of the platinum coating 1 is 0.03 mm, and the size of the niobium screw 4 is Ф13 mm × 180 mm. The diameter of the positioning hole 3 matches the diameter of the welded niobium screw, and the depth of the positioning hole 3 is 0.5 mm. The welding method includes the following steps:

[0063] Step 1: As shown in Fig. 1 and Fig. 2, process a Ф13 mm positioning hole 3 at the center position of the niobium plate 2, and clean the surfaces of the niobium screw 4 and the platinum / niobium composite plate with a positioning hole. Figure 1 and Figure 2 Fig. 2, clean the surfaces of the niobium screw 4 and the platinum / niobium composite plate with a positioning hole.

[0064] Step 2: Place the platinum coating 1 of the platinum / niobium composite plate cleaned in Step 1 downward and assemble it on the water-cooled copper tooling with a pressing device, so that the platinum coating 1 is pressed at the center of the sealing ring 8 of the cooling water tank 7. Fix the composite plate pressing plate 9 and the sealing pressing strip 10, and make the pressing force 2 KN to ensure that the platinum / niobium composite plate is in a horizontal state. There is a fixing screw on the composite plate pressing plate 9. When replacing the platinum / niobium composite plate, loosen the fixing screw, and the composite plate pressing plate 9 can be rotated to the edge of the tooling, which is convenient for disassembly and use. When fixing and replacing the platinum / niobium composite plate, the sealing pressing strip 10 can also be rotated to the edge of the tooling.

[0065] Step 3: Pass cooling water through the cooling water interface 11 into the cooling water tank 7 of the water-cooled copper tooling, with the cooling water flow rate being 15 L / min. Insert the niobium screw 4 cleaned in Step 1 into the positioning hole 3, and make the niobium screw 4 perpendicular to the surface of the platinum / niobium composite plate. Use a TA2 titanium alloy wire with a diameter of Ф2 mm and a clean and pollution-free surface as the filler wire, and use a tungsten argon arc welding gun to perform the first point positioning welding on the end of the niobium screw 4 and the platinum / niobium composite plate. Use a protective cover filled with an inert gas with a mass purity ≥99.99% to protect the first welding point. After the welding point cools to 50°C in the protective gas, then use a tungsten argon arc welding gun to perform the second point positioning welding on the opposite side of the first positioning point;

[0066] Step 4: Adjust the welding current to 230 A, control the molten pool depth and width within the minimum range, and use an intermittent welding process to weld the niobium screw and the platinum / niobium composite plate after the positioning welding in Step 3. That is, during welding, stop welding after one or two drops of the filler wire melt, and wait for the molten pool to cool in the inert gas before performing the next point welding. Repeat the welding multiple times until the entire circumference is welded. The mass purity of the inert gas ≥99.99%.

[0067] After welding in this embodiment, the platinum coating is complete, and the composite plate does not warp or deform.

[0068] Example 5

[0069] For the welding method of the platinum / niobium composite plate and the niobium screw in this embodiment, the platinum / niobium composite plate includes a niobium plate 2 and a platinum coating 1 attached to the niobium plate 2. The niobium plate 2 of the platinum / niobium composite plate has a thickness of 3 mm, a width of 80 mm, and a length of 500 mm; the thickness of the platinum coating 1 is 0.05 mm, and the size of the niobium screw 4 is Ф14 mm×180 mm. The diameter of the positioning hole 3 is matched with the diameter of the welded niobium screw, and the depth of the positioning hole 3 is 0.2 mm to 0.5 mm; the welding method includes the following steps:

[0070] Step 1: As shown in Figure 1 and Figure 2 , machine a Ф14 mm positioning hole 3 at the center position of the niobium plate 2, and clean the surfaces of the niobium screw 4 and the platinum / niobium composite plate with the positioning hole;

[0071] Step 2: Place the platinum coating 1 of the platinum / niobium composite plate cleaned in Step 1 downward, and assemble it on the water-cooled copper tooling with a pressing device, so that the platinum coating 1 is pressed at the center of the sealing ring 8 of the cooling water tank 7. Fix the composite plate pressing plate 9 and the sealing pressing strip 10, with the pressing force being 1 N, to ensure that the platinum / niobium composite plate is in a horizontal state. The composite plate pressing plate 9 has a fixing screw. When replacing the platinum / niobium composite plate, loosen the fixing screw, and the composite plate pressing plate 9 can be rotated to the edge of the tooling, which is convenient for disassembly and use. When fixing and replacing the platinum / niobium composite plate, the sealing pressing strip 10 can also be rotated to the edge of the tooling;

[0072] Step 3: Pass cooling water into the cooling water tank 7 of the water-cooled copper tooling through the cooling water interface 11. The flow rate of the cooling water is 10 L / min. Insert the niobium screw 4 cleaned in Step 1 into the positioning hole 3, and make the niobium screw 4 perpendicular to the surface of the platinum / niobium composite plate. Use a TA4 titanium alloy wire with a diameter of Ф2 mm and a clean and pollution-free surface as the filler wire. Use an argon arc welding torch to perform the first point positioning welding on the end of the niobium screw 4 and the platinum / niobium composite plate. Use a protective cover filled with an inert gas with a mass purity ≥99.99% to protect the first welding point. After the welding point cools to 70°C in the protective gas, use an argon arc welding torch to perform the second point positioning welding on the opposite side of the first positioning point;

[0073] Step 4: Adjust the welding current to 210 A, control the molten pool depth and width within the minimum range, and use an intermittent welding process to weld the niobium screw and the platinum / niobium composite plate after the positioning welding in Step 3. That is, during welding, stop welding after one or two drops of the filler wire melt. Wait for the molten pool to cool in the inert gas and then perform the next point welding. Repeat the welding multiple times until a full circle is welded. The mass purity of the inert gas ≥99.99%.

[0074] After welding in this embodiment, the platinum coating is complete, and the composite plate does not warp or deform.

[0075] Example 6

[0076] The welding method of the platinum / niobium composite plate and the niobium screw in this embodiment. The platinum / niobium composite plate includes a niobium plate 2 and a platinum coating 1 attached to the niobium plate 2. The thickness of the platinum / niobium composite plate is 5 mm, the width is 50 mm, and the length is 800 mm; the thickness of the platinum coating 1 is 0.02 mm, and the size of the niobium screw 4 is Ф12 mm × 180 mm. The diameter of the positioning hole 3 is matched with the diameter of the welded niobium screw, and the depth of the positioning hole 3 is 0.2 mm; the welding method includes the following steps:

[0077] Step 1: As shown in Figure 1 and Figure 2 , machine a Ф12 mm positioning hole 3 at the center position of the niobium plate 2, and clean the surfaces of the niobium screw 4 and the platinum / niobium composite plate with the positioning hole;

[0078] Step 2: Place the platinum coating 1 of the platinum / niobium composite plate cleaned in Step 1 downward on the water-cooled copper tooling with a pressing device, such that the platinum coating 1 is pressed at the center of the sealing ring 8 of the cooling water tank 7. Fix the composite plate pressing plate 9 and the sealing pressing strip 10, with a pressing force of 0.8 KN, ensuring that the platinum / niobium composite plate is in a horizontal state. The composite plate pressing plate 9 has a fixing screw. When replacing the platinum / niobium composite plate, loosen the fixing screw and the composite plate pressing plate 9 can be rotated to the edge of the tooling, which is convenient for disassembly and use. When fixing and replacing the platinum / niobium composite plate, the sealing pressing strip 10 can also be rotated to the edge of the tooling;

[0079] Step 3: Pass cooling water through the cooling water tank 7 of the water-cooled copper tooling through the cooling water interface 11, with a cooling water flow rate of 12 L / min. Insert the niobium screw 4 cleaned in Step 1 into the positioning hole 3, and make the niobium screw 4 perpendicular to the surface of the platinum / niobium composite plate. Use a TA3 titanium alloy wire with a diameter of Ф1 mm and a clean and pollution-free surface as the filler wire, and use a tungsten inert gas welding torch to perform the first point positioning welding on the end of the niobium screw 4 and the platinum / niobium composite plate. Use a protective cover filled with an inert gas with a mass purity ≥99.99% to protect the first welding point. After the welding point cools to 30 °C in the protective gas, perform the second point positioning welding on the opposite side of the first positioning point using a tungsten inert gas welding torch;

[0080] Step 4: Adjust the welding current to 215 A, control the molten pool depth and width within the minimum range, and use an intermittent welding process to weld the niobium screw and the platinum / niobium composite plate after the positioning welding in Step 3. That is, during welding, stop welding after one or two drops of the filler wire melt, and then perform the next point welding after the molten pool cools in the inert gas. Repeat the welding multiple times until the entire circumference is welded. The mass purity of the inert gas ≥99.99%.

[0081] After welding in this embodiment, the platinum coating is intact and the composite plate does not warp or deform.

[0082] Example 7

[0083] The welding method of the platinum / niobium composite plate and the niobium screw in this embodiment, the platinum / niobium composite plate includes a niobium plate 2 and a platinum coating 1 attached to the niobium plate 2. The platinum / niobium composite plate has a thickness of 3 mm, a width of 70 mm, and a length of 400 mm; the platinum coating 1 has a thickness of 0.05 mm, and the niobium screw 4 has a size of Ф15 mm × 180 mm. The diameter of the positioning hole 3 is matched with the diameter of the welded niobium screw, and the depth of the positioning hole 3 is 0.5 mm; the welding method includes the following steps:

[0084] Step 1: As shown in Figure 1 and Figure 2 , machine a Ф15 mm positioning hole 3 at the center position of the niobium plate 2, and clean the surfaces of the niobium screw 4 and the platinum / niobium composite plate with a positioning hole;

[0085] Step 2: Place the platinum cladding 1 of the cleaned platinum / niobium composite plate downward in the water-cooled copper tooling with a pressing device, such that the platinum cladding 1 is pressed at the center of the sealing ring 8 of the cooling water tank 7. Fix the composite plate pressing plate 9 and the sealing pressing strip 10, with a pressing force of 1.2 KN, ensuring that the platinum / niobium composite plate is in a horizontal state. The composite plate pressing plate 9 has a fixing screw. When replacing the platinum / niobium composite plate, loosen the fixing screw, and the composite plate pressing plate 9 can be rotated to the edge of the tooling, which is convenient for disassembly and use. When fixing and replacing the platinum / niobium composite plate, the sealing pressing strip 10 can also be rotated to the edge of the tooling;

[0086] Step 3: Pass cooling water into the cooling water tank 7 of the water-cooled copper tooling through the cooling water interface 11, with a cooling water flow rate of 5 L / min. Insert the niobium screw 4 cleaned in Step 1 into the positioning hole 3, and make the niobium screw 4 perpendicular to the surface of the platinum / niobium composite plate. Using a TC4 titanium alloy wire with a diameter of Ф3 mm and a clean and pollution-free surface as the filler wire, perform the first point positioning welding on the end of the niobium screw 4 and the platinum / niobium composite plate with an argon arc welding torch. Use a protective cover filled with an inert gas with a mass purity ≥ 99.99% to protect the first weld point. After the weld point cools to below 100 °C in the protective gas, perform the second point positioning welding on the opposite side of the first positioning point with an argon arc welding torch;

[0087] Step 4: Adjust the welding current to 235 A, control the molten pool depth and width within the minimum range, and use an intermittent welding process to weld the niobium screw and the platinum / niobium composite plate after the positioning welding in Step 3. That is, during welding, stop welding after one or two drops of the filler wire melt. Wait for the molten pool to cool in the inert gas and then perform the next point welding. Repeat the welding multiple times until the entire circumference is welded. The mass purity of the inert gas ≥ 99.99%.

[0088] After welding in this embodiment, the platinum cladding is intact, and the composite plate does not warp or deform.

[0089] The above is only a preferred embodiment of the present invention and does not impose any limitation on the present invention. Any simple modification, change, and equivalent variation made to the above embodiments based on the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A welding method for a platinum / niobium composite plate and a niobium screw, characterized in that, The platinum / niobium composite plate includes a niobium plate (2) and a platinum coating (1) attached to the niobium plate (2). The welding method includes the following steps: Step 1: Machine a positioning hole (3) at the center of the niobium plate (2), and clean the niobium screw (4) and the surface of the platinum / niobium composite plate with a positioning hole. Step 2: Assemble the platinum / niobium composite plate cleaned in Step 1 on a water-cooled copper tooling with a pressing device, and adjust the pressing device to ensure that the platinum / niobium composite plate is in a horizontal state. Step 3: Pass cooling water through the water-cooled copper tooling, insert the niobium screw (4) cleaned in Step 1 into the positioning hole (3), and make the niobium screw (4) perpendicular to the surface of the platinum / niobium composite plate. Use a low-melting-point titanium alloy wire that can mutually fuse with niobium metal as the filler wire to perform the first point positioning welding on the end of the niobium screw (4) and the platinum / niobium composite plate. Use a protective cover filled with inert gas to protect the first welding point. After the welding point cools to below 100°C in the protective gas, perform the second point positioning welding on the opposite side of the first positioning point. Step 4: Adjust the welding current, control the molten pool depth and width within the minimum range, and use an intermittent welding process to weld the niobium screw and the platinum / niobium composite plate after the positioning welding in Step 3.

2. The welding method of a platinum / niobium composite plate and a niobium screw according to claim 1, characterized in that, In Step 1, the thickness of the platinum / niobium composite plate is 1 mm to 5 mm, the width is 40 mm to 80 mm, and the length is 300 mm to 1000 mm; the thickness of the platinum coating (1) is 0.02 mm to 0.05 mm, the size of the niobium screw (4) is Ф(12 - 15) mm × 180 mm, the diameter of the positioning hole (3) matches the diameter of the welded niobium screw, and the depth of the positioning hole (3) is 0.2 mm to 0.5 mm.

3. A welding method for a platinum / niobium composite plate and a niobium screw according to claim 1, characterized in that, The water-cooled copper tooling with a pressing device in Step 2 includes an outer frame (5), a cooling copper mold (6) arranged in the middle of the outer frame (5), a composite plate pressing plate (9) and a sealing pressing strip (10) detachably installed on the outer frame (5). A columnar cooling water groove (7) is opened at the center of the cooling copper mold (6). The cooling water groove (7) is open, and a sealing ring (8) is arranged at the opening of the cooling water groove (7). Cooling water interfaces (11) are arranged on the front side and the rear side of the cooling water groove (7).

4. A welding method for a platinum / niobium composite plate and a niobium screw according to claim 1, characterized in that, In Step 3, the material of the titanium alloy wire is TA1, TA2, TA3, TA4, TC4 or TC26, and the diameter of the filler wire is Ф1 mm to Ф3 mm.

5. A welding method of a platinum / niobium composite plate and a niobium screw according to claim 1, characterized in that, In Step 3, the cooling water flow rate in the water-cooled copper tooling is 1 L / min to 20 L / min, and the pressing force of the pressing device in Step 2 is 0.1 KN to 3 KN.

6. A welding method of a platinum / niobium composite plate and a niobium screw according to claim 1, characterized in that, In Step 3, the mass purity of the inert gas ≥ 99.99%.

7. A welding method of a platinum / niobium composite plate and a niobium screw according to claim 1, characterized in that, In Step 4, the welding current is 200 A to 280 A.

8. A welding method for a platinum / niobium composite plate and a niobium screw according to claim 1, characterized in that, The intermittent welding process in Step 4 specifically includes: during welding, stop welding after one or two drops of the welding wire melt. Wait for the molten pool to cool in the inert gas and then perform the next point welding. Repeat the welding multiple times until the entire circumference is welded.

9. A welding method of a platinum / niobium composite plate and a niobium screw according to claim 8, characterized in that, The mass purity of the inert gas ≥ 99.99%.

Images