A repairing method of a molybdenum-tungsten alloy composite rotary target

Abstract

The application provides a molybdenum-tungsten alloy composite rotary target repairing method, which comprises six steps of target disc defect inspection, mechanical treatment, preliminary filling, electron beam cladding, stress relief annealing and post-treatment. The molybdenum-tungsten alloy composite rotary target repairing method of the application analyzes the information such as defect type, form, size, material composition and content of the waste molybdenum-tungsten composite rotary target disc or the molybdenum-tungsten composite rotary target with defects in the production process, adopts different filling methods, performs local cladding through an electron beam, and finally obtains the repaired molybdenum-tungsten alloy composite rotary target. The molybdenum-tungsten alloy composite rotary target repaired by the method has high density and high strength of the combined part, and the quality is equivalent to that of the original product, which can fully meet the use requirements of the X-ray tube, and effectively realizes the reuse of the waste molybdenum-tungsten composite rotary target disc or the molybdenum-tungsten composite rotary target with defects in the production process.

Description

Technical Field

[0001] This invention belongs to the field of rotating target technology for X-ray excitation, and relates to a molybdenum-tungsten alloy composite rotating target, specifically a method for repairing a molybdenum-tungsten alloy composite rotating target. Background Technology

[0002] CT (Computed Tomography) is a non-invasive, high-resolution imaging technology that clearly displays lesions inside the human body. It has become an indispensable tool in modern medical diagnosis and healthcare. The CT tube, or X-ray tube rotating anode, is the core component of the X-ray machine, serving as the X-ray source and considered the "core" of the CT scanner. The molybdenum-tungsten alloy composite rotating target is the "core within the core" of the CT scanner. Its working layer is composed of tungsten or a tungsten alloy, while the substrate is molybdenum or a molybdenum alloy. During operation, an electron beam bombards the working layer on the target disk, generating X-rays.

[0003] my country has nearly 30,000 CT scanners in operation, and this number is increasing annually. The molybdenum-tungsten alloy composite rotating targets operate under harsh conditions and are easily damaged, resulting in a large number of scrapped targets. Furthermore, tungsten metal is notch-sensitive, making cracks and notches highly susceptible to defects during the preparation, processing, and production of these targets. This significant waste of tungsten and molybdenum metal resources necessitates their utilization. Summary of the Invention

[0004] In view of the defects and deficiencies of the existing technology, the purpose of this invention is to provide a repair method for molybdenum-tungsten alloy composite rotating targets, thereby solving the technical problem of resource waste caused by the lack of a method for repairing waste molybdenum-tungsten alloy composite rotating targets or those defective during the production process.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A method for repairing a molybdenum-tungsten alloy composite rotating target, the method specifically includes steps one, two, 3.1, 4.1, five, and six, or specifically includes steps one, two, 3.2, 4.2, five, and six;

[0007] Step 1, inspect the target plate for defects:

[0008] Inspect the molybdenum-tungsten alloy composite rotating target to determine the type, material, location, and size of defects in the target disk;

[0009] Step 2, Mechanical processing:

[0010] Mechanical treatment is performed on the target plate defects in step one to remove the attached substances and oxide layer, so that the defective areas of the target plate are free of foreign matter and oxide traces and have a bright metallic luster.

[0011] Step 3, preliminary filling:

[0012] Step 3.1: Based on the inspection results in Step 1, determine the type of target plate defect as a melting pit, porosity, crack, or fissure. Then, based on the material and size of the target plate defect determined in Step 1, cut a repair material of the same material as the target plate defect. Deoxidize the repair material and place it on the target plate defect that has been mechanically treated in Step 2, ensuring that the repair material completely covers the target plate defect.

[0013] Step 3.2: Based on the inspection results in Step 1, after determining that the type of defect in the target disk is an erosion ring, cut ring-shaped repair material and circular repair material of the same material as the erosion ring according to the material and size of the erosion ring determined in Step 1. Deoxidize the ring-shaped repair material and circular repair material, then place the treated ring-shaped repair material on the erosion ring area, and then cover the entire target surface with circular repair material.

[0014] Step 4, Electron Beam Cladding:

[0015] Step 4.1: Load the target disk after preliminary filling in step 3.1 into the vacuum electron beam furnace, focus the electron beam on the upper end of the target disk defect, increase the electron beam power to melt the point, move the electron beam focus along the direction of the repair material layout, and clad the defect area of ​​the target disk until all defects are melted.

[0016] Step 4.2: Load the target disk after preliminary filling in step 3.2 into the vacuum electron beam furnace, focus the electron beam at the center of the target disk, increase the electron beam power to melt that point, and then continue to move the electron beam focus to perform concentric circle scanning cladding on the entire target surface until all the surface layers are completely melted.

[0017] Step 5, stress-relief annealing:

[0018] The target plate that has been clad in step four is placed in a vacuum furnace for stress-relieving annealing.

[0019] Step Six, Post-processing:

[0020] Take out the target disk that has been annealed in step five, perform machining on the target disk, and then inspect, clean and package it to obtain the repaired molybdenum-tungsten alloy composite rotating target.

[0021] The present invention also has the following technical features:

[0022] Specifically, in steps 3.1 and 3.2, the deoxidation treatment temperature is 800–900°C, and the holding time is 1–2 hours.

[0023] Specifically, in steps 4.1 and 4.2, the electron beam power is 40 to 100 kW, and the cladding time is 1 to 30 min.

[0024] Specifically, in step five, the stress-relief annealing temperature is 900–1200°C, and the holding time is 1–2 hours.

[0025] Specifically, in step 3.1, the volume of the repair material is 1.1 to 1.15 times the volume of the target disk defect.

[0026] Specifically, in step 3.2, the volume of the ring-shaped repair material is 1.1 to 1.15 times the volume of the eroded ring.

[0027] The beneficial technical effects of this invention compared to the prior art are as follows:

[0028] The present invention discloses a method for repairing a molybdenum-tungsten alloy composite rotating target. This method analyzes the defect type, morphology, size, material composition, and content of waste molybdenum-tungsten composite rotating target disks or those defective during the production process. Different filling strategies are employed, and local electron beam cladding is used to obtain the repaired molybdenum-tungsten alloy composite rotating target. The repaired molybdenum-tungsten alloy composite rotating target obtained using this method exhibits high density, high bonding strength, and quality comparable to the original product, fully meeting the requirements for X-ray tube use. This method effectively realizes the reuse of waste molybdenum-tungsten composite rotating target disks or those defective during the production process. Detailed Implementation

[0029] In this invention:

[0030] The molybdenum-tungsten alloy composite rotating target uses a molybdenum-tungsten alloy composite rotating target known in the technology. The base layer of the rotating target is made of molybdenum alloy, and the surface layer is made of tungsten alloy.

[0031] Target plate defects are located in the base layer and / or surface layer of the rotating target. Target plate defects include erosion rings caused by normal use, as well as various forms of defects such as erosion pits, pores, cracks, and fissures caused during production, transportation, and use.

[0032] Mechanical processing refers to various methods of processing such as turning, drilling, grinding, sandblasting, etc.

[0033] It should be noted that, unless otherwise specified, all devices used in this invention are those known in the art.

[0034] Following the above technical solutions, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0035] Example 1:

[0036] This embodiment provides a method for repairing a molybdenum-tungsten alloy composite rotating target, which specifically includes the following steps:

[0037] Step 1, inspect the target plate for defects:

[0038] An inspection of a 140mm diameter molybdenum-tungsten alloy composite rotating target revealed a crack on the edge of the surface layer of the target, measuring 2mm in length, 0.2mm in width, and 0.2mm in depth.

[0039] In this embodiment, the rhenium content in the surface layer of the rotating target is 10%, and the remainder is tungsten.

[0040] Step 2, Mechanical processing:

[0041] Using tools such as grinding wheels and angle grinders, the defects in the target plate from step one are polished to remove the attached substances and oxide layer, so that the defective parts of the target plate are free of foreign objects and oxide traces, and have a bright metallic luster.

[0042] Step 3, preliminary filling:

[0043] Based on the material and size of the target plate defect determined in step one, cut a tungsten-rhenium alloy wire of appropriate size, deoxidize the tungsten-rhenium alloy wire at 900℃ for 1 hour, and then place the treated tungsten-rhenium alloy wire on the target plate defect that has been polished in step two, and gently tap it with a small hammer to compact it.

[0044] As a specific embodiment, the cut tungsten-rhenium alloy wire is 2.2 mm long and 3 mm in diameter, with a rhenium content of 10% and the remainder being tungsten. The size of the cut tungsten-rhenium alloy wire is larger than the size of the crack, requiring a margin of more than 10% to ensure complete coverage of the crack.

[0045] Step 4, Electron Beam Cladding:

[0046] After the initial filling in step three, the target disk is loaded into a vacuum electron beam furnace. The electron beam focus is aimed at the upper end of the target disk defect, and the electron beam power is increased to melt the point. The electron beam focus is slowly moved along the tungsten rhenium alloy wire laying direction to perform line scanning cladding on the target disk defect area until all defects are completely melted.

[0047] In this embodiment, the electron beam power is 45 kW and the cladding time is 5 min.

[0048] Step 5, stress-relief annealing:

[0049] Place the target plate that has been clad in step four into a vacuum furnace for stress-relief annealing at a temperature of 1100℃ and a holding time of 120min.

[0050] Step Six, Post-processing:

[0051] Take out the target disk that has been annealed in step five, machine it according to the drawings, and then inspect, clean and package it to obtain the repaired molybdenum-tungsten alloy composite rotating target.

[0052] In this embodiment, the repaired molybdenum-tungsten alloy composite rotating target was visually inspected to confirm that it had no visible defects. After CT scanning, it was further confirmed that there were no abnormalities. Its appearance, density, size and other indicators all met the user's requirements.

[0053] Example 2:

[0054] This embodiment provides a method for repairing a molybdenum-tungsten alloy composite rotating target, which specifically includes the following steps:

[0055] Step 1, inspect the target plate for defects:

[0056] An inspection of a 160mm diameter molybdenum-tungsten alloy composite rotating target revealed a crack on the edge of the surface layer of the target, measuring 3mm in length, 0.2mm in width, and 0.1mm in depth.

[0057] In this embodiment, the rhenium content in the surface layer of the rotating target is 8%, with the remainder being tungsten.

[0058] Step 2, Mechanical processing:

[0059] Using tools such as grinding wheels and angle grinders, the defects in the target plate from step one are polished to remove the attached substances and oxide layer, so that the defective parts of the target plate are free of foreign objects and oxide traces, and have a bright metallic luster.

[0060] Step 3, preliminary filling:

[0061] Based on the material and size of the target plate defect determined in step one, cut a tungsten-rhenium alloy foil of appropriate size, deoxidize the tungsten-rhenium alloy foil at 900℃ for 1 hour, and then place the treated tungsten-rhenium alloy foil on the target plate defect that has been polished in step two, and gently tap it with a small hammer to compact it.

[0062] As a specific embodiment, the cut tungsten-rhenium alloy foil is 4mm long, 0.3mm wide, and 0.2mm thick, with a rhenium content of 8% and the remainder being tungsten. The size of the cut tungsten-rhenium alloy foil is larger than the size of the crack, requiring a margin of at least 10% to ensure complete coverage of the crack.

[0063] Step 4, Electron Beam Cladding:

[0064] After the initial filling in step three, the target disk is loaded into a vacuum electron beam furnace. The electron beam focus is aimed at the upper end of the target disk defect, and the electron beam power is increased to melt the point. The electron beam focus is slowly moved along the tungsten rhenium alloy wire laying direction to perform line scanning cladding on the target disk defect area until all defects are completely melted.

[0065] In this embodiment, the electron beam power is 60 kW and the cladding time is 12 min.

[0066] Step 5, stress-relief annealing:

[0067] Place the target plate that has been clad in step four into a vacuum furnace for stress-relief annealing at a temperature of 1100℃ and a holding time of 120min.

[0068] Step Six, Post-processing:

[0069] Take out the target disk that has been annealed in step five, machine it according to the drawings, and then inspect, clean and package it to obtain the repaired molybdenum-tungsten alloy composite rotating target.

[0070] In this embodiment, the repaired molybdenum-tungsten alloy composite rotating target was visually inspected to confirm that it had no visible defects. After CT scanning, it was further confirmed that there were no abnormalities. Its appearance, density, size and other indicators all met the user's requirements.

[0071] Example 3:

[0072] This embodiment provides a method for repairing a molybdenum-tungsten alloy composite rotating target, which specifically includes the following steps:

[0073] Step 1, inspect the target plate for defects:

[0074] An inspection of a molybdenum-tungsten alloy composite rotating target with a diameter of 140 mm confirmed that there was an etched ring on the surface layer of the rotating target, with a diameter of approximately 120 mm, a width of approximately 3 mm, and a depth of approximately 0.5 mm.

[0075] In this embodiment, the rhenium content in the surface layer of the rotating target is 5%, and the remainder is tungsten.

[0076] Step 2, Mechanical processing:

[0077] Sandblasting is used to treat the defects in the target plate in step one, removing the attached substances and oxide layer, so that the defective areas of the target plate are free of foreign matter and oxide traces, and have a bright metallic luster.

[0078] Step 3, preliminary filling:

[0079] Based on the material and size of the target disk defect determined in step one, cut tungsten-rhenium alloy foil rings and discs of appropriate size. Deoxidize the tungsten-rhenium alloy foil rings and discs at 900°C for 1 hour. Then, place the treated tungsten-rhenium alloy foil rings on the etched ring area and then cover the entire target surface with tungsten-rhenium alloy foil discs.

[0080] In one specific embodiment, the cut tungsten-rhenium alloy foil ring has a diameter of 122 mm, a width of 4 mm, and a thickness of 0.6 mm, with a rhenium content of 5% and the remainder being tungsten; the cut tungsten-rhenium alloy foil disc has a diameter of 140 mm, a thickness of 0.6 mm, and a rhenium content of 5% and the remainder being tungsten. The size of the cut tungsten-rhenium alloy foil ring is larger than the size of the etched ring, requiring a margin of approximately 10% or more to ensure complete coverage of the etched ring.

[0081] Step 4, Electron Beam Cladding:

[0082] After the initial filling in step three, the target disk is placed into the vacuum electron beam furnace. The electron beam focus is aligned with the center of the target disk. The electron beam power is increased to melt that point. The electron beam focus is slowly moved along a circular trajectory to gradually expand the area. Concentric circular scanning cladding is performed on the entire target surface until all the surface layers are completely melted.

[0083] In this embodiment, the electron beam power is 80 kW and the cladding time is 20 min.

[0084] Step 5, stress-relief annealing:

[0085] Place the target plate that has been clad in step four into a vacuum furnace for stress-relief annealing at a temperature of 1200℃ and a holding time of 120min.

[0086] Step Six, Post-processing:

[0087] Take out the target disk that has been annealed in step five, machine it according to the drawings, and then inspect, clean and package it to obtain the repaired molybdenum-tungsten alloy composite rotating target.

[0088] In this embodiment, the repaired molybdenum-tungsten alloy composite rotating target was visually inspected to confirm that it had no visible defects. After CT scanning, it was further confirmed that there were no abnormalities. Its appearance, density, size and other indicators all met the user's requirements.

Claims

1. A method for repairing a molybdenum-tungsten alloy composite rotating target, characterized in that, The method specifically includes steps one, two, 3.1, 4.1, five, and six, or specifically includes steps one, two, 3.2, 4.2, five, and six. Step 1, inspect the target plate for defects: Inspect the molybdenum-tungsten alloy composite rotating target to determine the type, material, location, and size of defects in the target disk; Step 2, Mechanical processing: Mechanical treatment is performed on the target plate defects in step one to remove the attached substances and oxide layer, so that the defective areas of the target plate are free of foreign matter and oxide traces and have a bright metallic luster. Step 3, preliminary filling: Step 3.1: Based on the inspection results in Step 1, determine the type of target plate defect as a melting pit, porosity, crack, or fissure. Then, based on the material and size of the target plate defect determined in Step 1, cut a repair material of the same material as the target plate defect. Deoxidize the repair material and place it on the target plate defect that has been mechanically treated in Step 2, ensuring that the repair material completely covers the target plate defect. Step 3.2: Based on the inspection results in Step 1, after determining that the type of defect in the target disk is an erosion ring, cut ring-shaped repair material and circular repair material of the same material as the erosion ring according to the material and size of the erosion ring determined in Step 1. Deoxidize the ring-shaped repair material and circular repair material, then place the treated ring-shaped repair material on the erosion ring area, and then cover the entire target surface with circular repair material. Step 4, Electron Beam Cladding: Step 4.1: Load the target disk after preliminary filling in step 3.1 into the vacuum electron beam furnace, focus the electron beam on the upper end of the target disk defect, increase the electron beam power to melt the point, move the electron beam focus along the direction of the repair material layout, and clad the defect area of ​​the target disk until all defects are melted. Step 4.2: Load the target disk after preliminary filling in step 3.2 into the vacuum electron beam furnace, focus the electron beam at the center of the target disk, increase the electron beam power to melt that point, and then continue to move the electron beam focus to perform concentric circle scanning cladding on the entire target surface until all the surface layers are completely melted. Step 5, stress-relief annealing: The target plate that has been clad in step four is placed in a vacuum furnace for stress-relieving annealing. Step Six, Post-processing: Take out the target disk that has been annealed in step five, perform machining on the target disk, and then perform testing, cleaning and packaging to obtain the repaired molybdenum-tungsten alloy composite rotating target. In steps 3.1 and 3.2, the deoxidation treatment temperature is 800–900°C, and the holding time is 1–2 hours; In steps 4.1 and 4.2, the electron beam power is 40–100 kW, and the cladding time is 1–30 min. In step five, the stress-relief annealing temperature is 900–1200°C, and the holding time is 1–2 hours; In step 3.1, the volume of the repair material is 1.1 to 1.15 times the volume of the target disk defect; In step 3.2, the volume of the ring-shaped repair material is 1.1 to 1.15 times the volume of the eroded ring.