Vacuum electron beam welding of platinum-iridium alloys

Abstract

The present application relates to a kind of vacuum electron beam welding methods of platinum iridium alloy, comprising the following steps: S1 is pretreated to the platinum iridium alloy plate to be welded, S2 is fixed after the pretreated platinum iridium alloy plate, so that the area to be welded is closely connected and located in electron beam welding work area;S3 sets up electron beam to seam parameter and welding parameter, vacuumizing, preheats the platinum iridium alloy plate to be welded, carries out welding;S4 is cooled after welding to the weldment.The welding method of the present application, it breaks through the technical defects existing in the welding of platinum iridium alloy, can be processed widely, and platinum iridium alloy plate and welding area after welding are not oxidized, no impurity element is introduced, platinum iridium noble metal volatilization loss is very small, ensures the uniformity of weld molten metal composition and organization.Postweld connection strength is reliable, no crack, pore and other welding defects, and the mechanical property is close to the welded joint of platinum iridium alloy, and the welding quality is excellent, provides a new optional thought for platinum iridium alloy processing technology.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of platinum-iridium alloy processing, and particularly relates to a vacuum electron beam welding method of platinum-iridium alloy. BACKGROUND

[0002] Platinum-iridium alloy (Pt-Ir) refers to a binary alloy containing iridium based on platinum, which has characteristics such as high hardness, high melting point, high corrosion resistance, and low contact resistance, and has excellent electrical conductivity and biocompatibility, and is widely used in fields such as electrical contact, microelectronics, aerospace, and biomedical devices. Platinum-iridium alloy has a high elastic modulus and Poisson's ratio, high mechanical strength, and is difficult to process and has a high work hardening rate; platinum-iridium alloy also has the characteristic that the processing performance decreases with the increase of iridium content, and belongs to an alloy type with relatively high processing difficulty. At present, platinum-iridium alloy billets are usually formed by investment casting, which has a short casting cycle and low cost, but is prone to defects such as segregation, shrinkage, and porosity, so it can only be formed in the simplest square or cylindrical shape. After casting, simple shaping can only be achieved through post-processing methods such as hot rolling, and it is difficult to obtain workpieces with various structures. Therefore, the welding technology of platinum-iridium alloy is of great practical significance for obtaining workpieces with various shapes and expanding the engineering application of platinum-iridium alloy.

[0003] Electron beam welding technology has unique excellent characteristics such as small molten pool, large depth-to-width ratio, low joint stress, and small workpiece deformation; it has good weld structure and low thermal residual stress, and this welding method does not introduce other elements, so the alloy composition of the welded part is controllable, and in theory it meets the welding requirements of platinum-iridium alloy workpieces. However, existing literature does not carry out related research on electron beam welding of platinum-iridium alloy, and whether electron beam welding is suitable for platinum-iridium alloy welding still needs to be demonstrated through experiments.

[0004] Through extensive literature review on platinum-iridium alloy processing, it can be known that at present, platinum-iridium alloy workpiece preparation almost entirely adopts the mode of casting, extrusion, hot rolling, cold rolling, cold drawing, or lathe processing. Patent document CN118003084A discloses a method for platinum-iridium alloy suction casting, extrusion, and cold drawing into a tube; patent document CN115418724A discloses a method for platinum-iridium alloy smelting combined with directional solidification into a rod; and patent document CN116623034A discloses a method for platinum-iridium alloy directional solidification into a tube and isothermal drawing into a micro tube. The above methods can only obtain platinum-iridium alloy workpieces with simple structure and single shape. Patent document CN112872090A discloses a method for platinum-iridium ingot extrusion into a rod and turning + grinding into a thin-walled tube; and patent document CN118003045A discloses a processing method in which laser cutting is used to process micro-holes in platinum-iridium thin plates. Both of these methods involve subtractive manufacturing of platinum-iridium workpieces, which will result in a large amount of platinum-iridium noble metal loss and extremely high cost.

[0005] Welding is an effective method for connecting platinum-iridium alloy parts and obtaining complex structural elements. Welding has been used in the processing of some platinum-iridium alloy products. In the field of welding, patent document CN118003045A discloses a method for welding platinum-iridium microtubes and platinum-iridium thin plates using laser welding. However, laser welding has the problems of low heat input, small penetration, and difficulty in welding high-reflectivity alloys. In this method, the thickness of the workpiece sheet is only 0.05-0.01mm. In the method disclosed in patent document CN101456100A, platinum-iridium ultrafine wires and platinum alloy rings are connected using laser welding. This method has the advantages of slight processing of welding spots, high welding speed, small heat damage to the rest of the workpiece, and no pollution to the welding point. However, this method only performs single-point welding, and the overall structural strength of the platinum-iridium alloy part after welding is not considered. In patent document CN106677905A, a welding method using laser welding and threaded fastening is disclosed. However, the main role of welding in this method is to ensure that the threads do not loosen, and the platinum-iridium igniter electrode does not bear stress. The main fastening effect is generated by the threads. In summary, existing platinum-iridium alloy laser welding is mainly used for simple cases with small thickness, low penetration requirement, and low welding strength requirement. Patent document CN105886826A provides a platinum-iridium-zirconium-tungsten-thorium alloy solder for welding connections required for complex iridium alloy parts, filling the gap for alloy solder with similar strength to the welding seam and iridium alloy at high temperatures of 1000-1800℃, resistance to acid and alkali corrosion, and high-temperature oxidation. Using this solder for welding or brazing, the strength of the welding seam after forming is close to the original workpiece strength. However, this welding method requires heating the workpiece to a temperature of 1820℃ or higher in most areas or the entire workpiece during processing. This heating temperature is close to the melting point of commonly used platinum-iridium alloys (1750-1850℃), which will cause serious and unacceptable heat effects on the heated workpiece. At the same time, this processing method introduces multiple added elements, which is obviously not suitable for processing cases that require clean workpiece composition or high biocompatibility. Similarly, patent document CN110449681A discloses the use of pure copper solder T-3 for welding platinum-iridium alloys with low-carbon steel, but it is not suitable for welding between platinum-iridium alloys.

[0006] Therefore, there is a need to develop a new welding method to expand the processing means of platinum-iridium alloys. SUMMARY

[0007] In view of the deficiencies of the existing processing techniques for platinum-iridium alloys, the inventors have conducted in-depth research on various welding processes for platinum-iridium alloys in production practice, and finally determined to provide a vacuum electron beam welding method for platinum-iridium alloys.

[0008] The specific technical solutions of the present application are as follows:

[0009] A vacuum electron beam welding method for platinum-iridium alloys, comprising the following steps:

[0010] S1 pretreating the platinum-iridium alloy plate to be welded,

[0011] S2 fixing the pretreated platinum-iridium alloy plate so that the to-be-welded area is closely connected and located in the electron beam welding working area;

[0012] S3 setting the electron beam seam parameters and welding parameters, vacuumizing, preheating the platinum-iridium alloy plate to be welded, and welding;

[0013] S4 cooling the welded part after welding.

[0014] Further, the composition of the platinum-iridium alloy ranges from platinum: iridium = 95%: 5% to 70%: 30% in terms of element percentage.

[0015] Further, in step S1, the pretreatment includes at least one of grinding, ultrasonic cleaning, and acid boiling. The machining burrs, adhered contaminants, etc. are mainly removed by grinding. The surface can be cleaned by ultrasonic cleaning to remove surface oil, dust, etc. Alcohol ultrasonic cleaning or water ultrasonic cleaning can be used as needed. Acid boiling is mainly to clean by dilute acid to remove possible impurity metals. The above pretreatment methods can be used as needed, and the main purpose is to clean the welding surface by pretreatment.

[0016] Further, in step S3, the electron beam seam parameters are as follows: acceleration voltage 20-40KV; focusing current 300-500mA; bias voltage 500V; seam beam current 0.5-2.5mA; seam speed 500-700mm / min; scanning frequency 10-40Hz; X, Y axis scanning range 50-350;

[0017] The welding vacuum degree is 1×10 -4 Pa-6×10 -2 Pa, and the welding parameters are as follows: acceleration voltage 50-70KV; focusing current 500-900mA; bias voltage 1000-1500V; welding beam current 5-15mA; welding speed 400-900mm / min; scanning frequency 40-110Hz; X, Y axis scanning range 100-550.

[0018] Further, when the content of iridium in the platinum-iridium alloy is 20wt%-30wt%, the welding vacuum degree is 1×10 -3 Pa-6×10 -2Pa; welding parameters: accelerating voltage 50-60KV; focusing current 700-900mA; bias voltage 1000-1500V; welding beam current 5-8mA; welding speed 600-800mm / min; scanning frequency 70-110Hz; X, Y axis scanning range 100-300, the noble metal has less weight loss, and the welding quality and efficiency are better.

[0019] Further, if the gap span of the unconnected gap in the to-be-welded area after fixing in step S2 is less than or equal to 0.5mm, no filler metal is needed; in welding, the electron beam gap parameters are as follows: accelerating voltage 20-40KV; focusing current 400-500mA; bias voltage 500V; gap beam current 0.5-2mA; gap speed 500-700mm / min; scanning frequency 10-30Hz; X, Y axis scanning range 50-300; and the electron beam welding parameters are as follows: accelerating voltage 50-70KV; focusing current 500-700mA; bias voltage 1000-1500V; welding beam current 5-10mA; welding speed 400-700mm / min; scanning frequency 40-100Hz; X, Y axis scanning range 200-500.

[0020] Further, if there is an unconnected gap in the to-be-welded area after fixing in step S2, and the gap span is greater than 0.5mm but less than 2mm, a filler metal is used to fill and fix the gap, and the filler metal is a platinum-iridium alloy strip with similar shape and same composition. By controlling the gap size and using the same composition of filler metal, new impurity elements are avoided. At the same time, the related welding parameters are adjusted, the electron beam gap parameters are as follows: accelerating voltage 20-40KV; focusing current 300-500mA; bias voltage 500V; gap beam current 1.5-2.5mA; gap speed 500-700mm / min; scanning frequency 10-40Hz; X, Y axis scanning range 250-350; and the electron beam welding parameters are as follows: accelerating voltage 60-70KV; focusing current 500-800mA; bias voltage 1000-1500V; welding beam current 7-13mA; welding speed 700-900mm / min; scanning frequency 40-100Hz; X, Y axis scanning range 250-550.

[0021] Further, in step S3, the platinum-iridium alloy welding part filled with the filler metal is preheated by a reciprocating gap scanning method to ensure the molten pool formed by the electron beam in welding.

[0022] Further, step S3 also includes shaping the welding area, and the electron beam welding parameters for shaping are as follows: welding beam current 2-4mA; X, Y axis scanning range 200-500. By shaping, the surface morphology of the welding part can be more regular, and subsequent processing requirements can be met.

[0023] Further, in step S4, after the welding is completed, the workpiece is cooled in a furnace cooling mode; or, 1-3 minutes after the welding is completed, the welding chamber is filled with air, and the welded workpiece is quickly taken out for water cooling, so as to further improve the strength of the weld. 1-3 minutes after the welding is completed, the welding chamber is filled with air, and the welded workpiece is quickly taken out for water cooling (at room temperature), so as to avoid high-temperature solid phase decomposition of the platinum-iridium alloy during cooling; and also to avoid welding defects and thermal cracks at the welded part, reduce the influence of welding stress, and improve the microstructure and performance of the platinum-iridium alloy at the welded part.

[0024] The beneficial effects of the present application are:

[0025] The platinum-iridium alloy vacuum electron beam welding method provided by the present application breaks through the technical defects existing in the welding of platinum-iridium alloy, has a wide processing range, and the platinum-iridium alloy plate and the welded area after welding are free of oxidation and introduction of impurity elements, the volatilization loss of platinum-iridium noble metal is extremely small, and the uniformity of the composition and organization of the molten metal of the weld is ensured. The connection strength after welding is reliable, and there are no welding defects such as cracks and pores, the mechanical properties are close to those of the welded joint of platinum-iridium alloy, the welding quality is excellent, and a new optional idea is provided for the platinum-iridium alloy processing technology. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The microstructure photo of the welded platinum-iridium alloy part. DETAILED DESCRIPTION

[0027] The present application provides a platinum-iridium alloy vacuum electron beam welding method, comprising the following steps:

[0028] S1 pretreatment of the platinum-iridium alloy plate to be welded.

[0029] The pretreatment includes polishing, ultrasonic cleaning, acid boiling and the like.

[0030] Polishing mainly removes processing burrs, adhered contaminants and the like by using water-resistant sandpaper.

[0031] Ultrasonic cleaning can clean the surface and remove surface oil stains, dust and the like, and can use alcohol ultrasonic cleaning or water ultrasonic cleaning according to needs. After cleaning, a hot air gun or a box-type drying device is used for drying treatment of the cleaned workpiece.

[0032] Acid cooking, mainly through the cleaning of dilute acid, to remove possible impurities metal. Dilute acid can be 5% ~ 10% dilute sulfuric acid, etc. Acid cooking, the solution in the reaction phenomenon stops, and then take out the workpiece and use a lot of water to flush the workpiece surface; after using the ultrasonic cleaner filled with deionized water, at 28 kHz frequency on the workpiece ultrasonic cleaning 15 ~ 60 minutes, to ensure that the platinum-iridium alloy workpiece surface clean no pollution before welding. Finally, using hot air gun or box drying equipment for drying of the cleaned workpiece.

[0033] The above pretreatment means, can be selected according to the need to use, the main purpose is through the pretreatment of the welding surface clean no pollution, and not damage the welding parts.

[0034] For example, if the surface of the workpiece to be welded oil pollution is serious, can increase the high purity alcohol ultrasonic cleaning step. Using the ultrasonic cleaner filled with high purity alcohol at 28 Hz frequency cleaning 3 ~ 8 minutes; after cleaning, with clean alcohol flush the workpiece surface and directly into the box dryer for drying treatment.

[0035] If the workpiece to be welded already exists more fragile early processing results, such as already welded into the lead, can be omitted acid cooking step, and in the deionized water cleaning stage, select 28 Hz frequency ultrasonic cleaning.

[0036] S2 will be fixed after the pretreatment of platinum-iridium alloy plate, so that the welding area is closely connected and located in the electron beam welding work area.

[0037] This step is mainly to fix the platinum-iridium alloy plate to be welded, to ensure that the welding area is closely connected. Generally through the clamp fixed, by adjusting the clamping position of the clamp to avoid the welding area, put the clamp into the electron beam welding machine work platform, test the platform motion limit and adjust the clamp position to ensure that the welding area is located in the electron beam welding work area.

[0038] If there is a gap in the welding area after fixing, and the gap span is greater than 0.5 mm but less than 2 mm, the gap is filled and fixed with solder. The solder can be a platinum-iridium alloy strip of similar shape and same composition. The platinum-iridium alloy strip can be obtained by rolling and cutting, and filled and fixed by extrusion or laser welding. By filling with the same composition of solder, new impurity elements can be avoided.

[0039] If the unconnected gap is less than or equal to 0.5 mm after fixing, it can be directly welded. If the unconnected gap span is greater than or equal to 2 mm, further adjustment is needed. When the gap width meets the range, the gap is filled and fixed with solder.

[0040] S3 sets the electron beam to seam parameters and welding parameters, vacuum, preheating the platinum-iridium alloy plate to be welded, and welding.

[0041] In particular operation, the electron beam welding machine can be started first, and the electron beam seam parameters are set. Then the vacuum system is started to extract the electron beam welding device cavity to the welding working vacuum degree. In the process of waiting for vacuum extraction, the electron beam welding parameters are set. Then the electron beam emitting structure is preheated, and then the electron beam seam system is started. The electron beam focusing condition is tested to determine the electron beam welding point movement condition, and the platinum-iridium alloy plate is preheated. Then the welding program is started to weld the platinum-iridium alloy plate.

[0042] The electron beam seam parameter range can be: acceleration voltage 20-40KV; focusing current 300-500mA; bias 500V; seam beam current 0.5-2.5mA; seam speed 50-7000mm / min; scanning frequency 10-40Hz; X, Y axis scanning range 50-350; the welding vacuum degree range can be 1x10 -4 Pa-6x10 -2 Pa, the welding parameter range can be: acceleration voltage 50-70KV; focusing current 500-900mA; bias 1000-1500V; welding beam current 5-15mA; welding speed 400-900mm / min; scanning frequency 40-110Hz; X, Y axis scanning range 100-550.

[0043] For conventional welding plates, i.e. tightly connected, after fixing, the unconnected gap is less than or equal to 0.5mm, and the welded part does not need to be filled with solder, the electron beam seam parameter range is: acceleration voltage 20-40KV; focusing current 400-500mA; bias 500V; seam beam current 0.5-2mA; seam speed 500-700mm / min; scanning frequency 10-30Hz; X, Y axis scanning range 50-300; the welding parameter range is: acceleration voltage 50-70KV; focusing current 500-700mA; bias 1000-1500V; welding beam current 5-10mA; welding speed 400-700mm / min; scanning frequency 40-100Hz; X, Y axis scanning range 200-500, and the welding quality is better.

[0044] And for the above-mentioned welded parts that need to be filled with solder, the electron beam seam parameter range is: acceleration voltage 30-40KV; focusing current 300-500mA; bias 500V; seam beam current 1.5-2.5mA; seam speed 500-700mm / min; scanning frequency 10-40Hz; X, Y axis scanning range 250-350; the electron beam welding parameter is as follows: acceleration voltage 60-70KV; focusing current 500-800mA; bias 1000-1500V; welding beam current 7-13mA; welding speed 700-900mm / min; scanning frequency 40-100Hz; X, Y axis scanning range 250-550, and the welding quality is better.

[0045] Furthermore, for weldments filled with solder, it is preferable to use a reciprocating seam scanning method for secondary preheating to ensure the depth of the molten pool formed by the electron beam during welding.

[0046] Furthermore, as the iridium concentration and heating temperature increase, the volatilization weight loss of platinum-iridium alloys increases, leading to the loss of precious metal materials. This is especially true when the iridium content in the platinum-iridium alloy to be welded is high (20%–30%). Therefore, increasing the vacuum level in the welding working zone and adjusting the welding speed are typically used to reduce alloy thermal volatilization. The welding vacuum level is generally set within the range of 1 × 10⁻⁶. - 4 Pa ~ 1×10 -3 Pa. However, increasing the vacuum level will significantly prolong the system evacuation time. Preferably, when the iridium content in the platinum-iridium alloy is 20wt% to 30wt%, the welding vacuum level is 1×10. -3 Pa~6×10 -2 The welding parameters are as follows: accelerating voltage 50-60KV; focusing current 700-900mA; bias voltage 1000-1500V; welding beam current 5-8mA; welding speed 600-800mm / min; scanning frequency 70-110Hz; X and Y axis scanning range 100-300. The precious metals have less volatilization and weight loss, and can well balance welding quality and welding efficiency.

[0047] If the platinum-iridium alloy workpiece has subsequent processing requirements or surface morphology requirements that include the welding area, the weld can be reheated and reshaped by reducing the welding beam current and increasing the scanning area. The adjusted electron beam welding parameters are as follows: welding beam current 2-4mA; X and Y axis scanning range 200-500, and the welding quality is better within the range.

[0048] After S4 welding is completed, the weldment is cooled.

[0049] Generally, for ordinary welded workpieces, there are no special requirements for the strength of the weld joint. After welding, the workpiece can be cooled by slow cooling in the furnace. That is, the welded workpiece is placed in the vacuum furnace and waited for 10-30 minutes to allow the workpiece to cool slowly.

[0050] If the weld strength requirement is high, the weld performance can be improved by rapid water cooling, specifically, the welding chamber can be inflated after 1-3 minutes of welding, and the welded part is quickly taken out for water cooling. When platinum-iridium alloy is cooled from high temperature to about 900 DEG C, very slow solid phase decomposition occurs. If the platinum-iridium alloy welded part needs higher metal strength in the process, the welding chamber can be inflated after 1-3 minutes of welding, and the welded part is quickly taken out for water cooling to avoid the generation of solid phase decomposition, and also to avoid the generation of welding defects and thermal cracks at the welded part, reduce the influence of welding stress, and improve the microstructure and performance of the platinum-iridium alloy at the welded part.

[0051] The vacuum electron beam welding method of the platinum-iridium alloy provided by the application is suitable for the platinum-iridium alloy with a composition range of platinum: iridium = 95%: 5% to 70%: 30% (element percentage).

[0052] The application will be further described below in combination with specific examples, but the examples do not limit the application in any form. Unless otherwise specified, the reagents, methods and equipment used in the application are conventional reagents, methods and equipment in the technical field. Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0053] Example 1: A high vacuum electron beam welding method of platinum-iridium 25 alloy

[0054] The workpiece to be welded is two identical platinum-iridium 25 rectangular plates with a thickness of 3 mm and a flat edge; the composition is as follows: in terms of element percentage, the platinum-iridium alloy plate to be processed is composed of the following elements: Pt content 75%, Ir content 25%.

[0055] The specific welding method includes the following steps:

[0056] S1. Use brown corundum water-resistant sandpaper to polish the long edge of the platinum-iridium alloy plate, then put the polished plate into a 5% dilute sulfuric acid solution for acid boiling, take out the plate after the acid boiling reaction stops, and wash it with a large amount of clean water; then put it into a ultrasonic cleaning machine, use deionized water to clean at a frequency of 28 kHz for 20 minutes, and put the cleaned workpiece into a box dryer and dry at 70 DEG C for 15 minutes.

[0057] S2. Fixing: fix the long edges of the two cleaned platinum-iridium 25 plates on the welding fixture respectively, and connect the long edges to form the position to be welded, move the position to be welded to the protection area of the fixture and lock the fixture. Put the whole set of platinum-iridium 25 plates and the fixture into the electron beam welding working area to ensure that the weld movement track is within the working range of the working platform.

[0058] S3. Welding.

[0059] S31 power on the electron beam welding machine, set the parameters for the seam and start the vacuum system, the parameters for the seam are as follows: vacuum degree 6x10 -2 Pa; accelerating voltage 40KV; focusing current 500mA; bias 500V; beam current for the seam 2mA; seam speed 700mm / min; scanning frequency 30Hz; X, Y axis scanning range 150;

[0060] S32 during the operation of the vacuum system, set the parameters for the electron beam welding, the parameters are as follows: accelerating voltage 60KV; focusing current 900mA; bias 1500V; welding beam current 7mA; welding speed 600mm / min; scanning frequency 70Hz; X, Y axis scanning range 100.

[0061] S33 preheat the electron beam emission system, start the electron beam seam program and preheat once, and confirm that the electron beam seam program and the welding trajectory run correctly.

[0062] S34 start the electron beam welding program for welding.

[0063] S35 after welding, observe the surface morphology of the weld, which has a slight bulge, in order to reduce the loss of post-processing, start the weld surface shaping, the shaping parameters are as follows: accelerating voltage 60KV; focusing current 900mA; bias 1500V; welding beam current 2mA; welding speed 700mm / min; scanning frequency 70Hz; X, Y axis scanning range 200.

[0064] S4 cooling

[0065] After the shaping is completed, observe the weld surface morphology, which is correct, start the electron beam welding machine cavity inflation program after 1 minute, after the inflation is completed, open the cavity cover, take out the fixture and the plate as a whole for water cooling.

[0066] The platinum-iridium 25 alloy sample obtained by electron beam welding in Example 1 is subjected to mechanical property testing and metallographic structure observation. The mechanical property testing results of the welded sample are shown in Table 1, and the metallographic structure is shown in Figure 1 In Table 1, the mechanical properties of the platinum-iridium 25 alloy welded sample are lower than those of the processed plate, but close to those of the annealed plate. Through the metallographic structure analysis of Figure 1 , the reason may be that the original plate of the welded sample is in a processed state, the grain is fine, and the more grain boundaries block the dislocation movement, so the tensile strength is larger but the elongation is reduced; the metal in the weld is heated significantly, the grain size is larger, and there is a certain iridium segregation on the surface, so the mechanical properties of the welded sample are different from those of the processed sample, but close to those of the annealed sample. However, there is almost no dislocation, deformation, etc. at the interface of the platinum-iridium alloy plate on both sides of the weld, the distribution of the structure in the weld is uniform, and there is no obvious welding defects such as pores and shrinkage. This shows that the welding quality of this method is excellent.

[0067] Table 1 Mechanical properties of welded test specimens

[0068]

[0069] Each technical feature of the above-described embodiments can be combined with any other technical feature, and for the sake of brevity, not all possible combinations are described. It should be noted that, unless otherwise explicitly provided herein, any combination of the technical features described herein can be claimed. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, and these should all fall within the scope of the present application. Therefore, the scope of protection of the present application should be subject to the appended claims.

Claims

1. A vacuum electron beam welding method of a platinum-iridium alloy, characterized by, The method comprises the following steps: S1, pre-treating the platinum-iridium alloy plate to be welded, S2, fixing the pre-treated platinum-iridium alloy plate so that the to-be-welded area is closely connected and located in the electron beam welding working area; S3 sets the electron beam seam parameters and welding parameters, evacuates, preheats the platinum-iridium alloy plate to be welded, and performs welding; in step S3, the electron beam seam parameters are as follows: accelerating voltage 20-40KV; focusing current 300-500mA; bias voltage 500V; seam beam current 0.5-2.5mA; seam speed 500-700mm / min; scanning frequency 10-40Hz; X, Y axis scanning range 50-350; welding vacuum degree 1x10 -4 Pa-6x10 -2 Pa; the welding parameters are as follows: accelerating voltage 50-70KV; focusing current 500-900mA; bias voltage 1000-1500V; welding beam current 5-15mA; welding speed 400-900mm / min; scanning frequency 40-110Hz; X, Y axis scanning range 100-550; If the gap span of the unconnected area in the to-be-welded area after being fixed in step S2 is less than or equal to 0.5 mm, no filler metal is needed; during welding, the electron beam butt joint parameters are as follows: accelerating voltage 20-40 KV; focusing current 400-500 mA; bias 500 V; butt joint beam current 0.5-2 mA; butt joint speed 500-700 mm / min; scanning frequency 10-30 Hz; X, Y axis scanning range 50-300; the electron beam welding parameters are as follows: accelerating voltage 50-70 KV; focusing current 500-700 mA; bias 1000-1500 V; welding beam current 5-10 mA; welding speed 400-700 mm / min; scanning frequency 40-100 Hz; X, Y axis scanning range 200-500; If the gap span of the unconnected area in the to-be-welded area after being fixed in step S2 is greater than 0.5 mm but less than 2 mm, the gap is filled and fixed by using a platinum-iridium alloy strip with similar shape and same composition; during welding, the electron beam butt joint parameters are as follows: accelerating voltage 30-40 KV; focusing current 300-500 mA; bias 500 V; butt joint beam current 1.5-2.5 mA; butt joint speed 500-700 mm / min; scanning frequency 10-40 Hz; X, Y axis scanning range 250-350; the electron beam welding parameters are as follows: accelerating voltage 60-70 KV; focusing current 500-800 mA; bias 1000-1500 V; welding beam current 7-13 mA; welding speed 700-900 mm / min; scanning frequency 40-100 Hz; X, Y axis scanning range 250-550; S4, cooling the welded workpiece after welding.

2. The vacuum electron beam welding method of a platinum-iridium alloy according to claim 1, characterized by, The platinum-iridium alloy has a composition range of platinum: iridium = 95%: 5%-70%: 30% in terms of element percentage.

3. The vacuum electron beam welding method of a platinum-iridium alloy according to claim 1, characterized by, In step S1, the pre-treatment includes at least one of grinding, ultrasonic cleaning, and acid boiling.

4. The vacuum electron beam welding method of a platinum-iridium alloy according to claim 2, characterized by, When the content of iridium in the platinum-iridium alloy is 20 wt%-30 wt%, Welding vacuum 1 x 10 -3 Pa ~ 6 x 10 -2 Pa; The welding parameters are as follows: accelerating voltage 50-60 KV; focusing current 700-900 mA; bias 1000-1500 V; welding beam current 5-8 mA; welding speed 600-800 mm / min; scanning frequency 70-110 Hz; X, Y axis scanning range 100-300. In step S3, the preheating is performed by using a method of reciprocating butt joint scanning and preheating twice.

5. The vacuum electron beam welding method of a platinum-iridium alloy according to claim 1, characterized by, In step S3, the method further comprises reshaping the welding area, and the electron beam welding parameters for the reshaping are as follows: welding beam current 2-4 mA; X, Y axis scanning range 200-500.

6. The vacuum electron beam welding method of a platinum-iridium alloy according to claim 1, characterized by, In step S4, after welding is completed, the workpiece is cooled in a furnace cooling manner; 7. The vacuum electron beam welding method of a platinum iridium alloy according to claim 1, characterized by, Or, after welding is completed for 1-3 minutes, the welding chamber is filled with gas, and the welded workpiece is quickly taken out for water cooling. ​

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