阅读说明：本技术 一种增强复合靶材寿命的焊接方法 (Welding method for prolonging service life of composite target material ) 是由 童剑飞 朱凌波 史英丽 梁天骄 于 2021-07-02 设计创作，主要内容包括：本发明提供一种增强复合靶材寿命的焊接方法,在作为被焊物靶体外的铜层上通过阻焊材料焊上超薄钽、钒层；包括以下步骤：S1,原材料加工,采用线切割方式从纯钽或钒方棒切取试样,并在打磨抛光后清洗干燥,制得钽箔和钒箔后备用；S2,部件装配,在部件装配过程中,钽、钒箔片与铜块表面平面接触；S3,热等静压扩散焊接,采用电子束焊接包套,保持包套内部处于真空状态；S4,机械加工；S5,焊接质量检测,通过观察焊接界面是否有缺陷来进行焊接强度的评测,采用热等静压扩散焊接方法焊接,保证焊后钽箔无褶皱、不变形；采用阻焊材料阻止包套与钽片焊接,拆包套时钽箔表面不用加工,从而保证钽箔厚度满足技术要求,同时提高复合靶材产品的良率。(The invention provides a welding method for prolonging the service life of a composite target, which is characterized in that an ultra-thin tantalum layer and a vanadium layer are welded on a copper layer outside a target body serving as a welded object through a solder resist material; the method comprises the following steps: s1, processing raw materials, cutting a sample from a pure tantalum or vanadium square rod by adopting a linear cutting mode, polishing, cleaning and drying to obtain tantalum foil and vanadium foil for later use; s2, assembling the components, wherein in the process of assembling the components, the tantalum foil and the vanadium foil are in plane contact with the surface of the copper block; s3, performing hot isostatic pressure diffusion welding, and welding the sheath by adopting an electron beam to keep the interior of the sheath in a vacuum state; s4, machining; s5, detecting welding quality, evaluating welding strength by observing whether a welding interface has defects or not, and welding by adopting a hot isostatic pressing diffusion welding method to ensure that the tantalum foil after welding has no folds and deformation; and the welding of the sheath and the tantalum sheet is prevented by adopting a solder resist material, and the surface of the tantalum foil is not required to be processed when the sheath is detached, so that the thickness of the tantalum foil is ensured to meet the technical requirement, and the yield of the composite target product is improved.)

1. A welding method for prolonging the service life of a composite target material is characterized in that: the welding method is to weld ultra-thin tantalum and vanadium layers on a copper layer outside a target body serving as a welded object through a solder resist material.

2. The welding method for enhancing the life of a composite target according to claim 1, wherein: the method comprises the following steps:

s1, processing raw materials, namely cutting a sample from a pure tantalum or vanadium square rod, processing an oxygen-free copper material into a copper block with a specified size and taking the copper block as a welded object, and manufacturing a corresponding metal sheath according to the size of the copper block;

s2, assembling parts, namely assembling the tantalum, vanadium and copper blocks into the metal sheath, wherein in the assembling process, the tantalum and vanadium foil sheets are in plane contact with the surface of the copper block;

s3, performing hot isostatic pressure diffusion welding, and welding the sheath by adopting an electron beam to keep the interior of the sheath in a vacuum state;

s4, machining, and placing the welded sheath into hot isostatic pressing equipment for temperature-controlled diffusion welding;

and S5, detecting the welding quality, and evaluating the welding strength by observing whether the welding interface has defects.

3. The welding method of claim 2, wherein the step of welding comprises: the cutting thickness of the sample in the step of S1 is 0.5-1.5mm, and then grinding and polishing are performed so that the thicknesses of the tantalum foil and the vanadium foil are processed to 0.1-0.5 mm.

4. The welding method of claim 2, wherein the step of welding comprises: and cleaning the sample in the step S1 by using acetone as a solution, spraying the cleaned sample with alcohol, and finally drying the sample.

5. The welding method of claim 2, wherein the step of welding comprises: and in the assembling process in the step S2, the environment is clean, no polluting substances such as dust, oil stains and the like enter the interface of the tantalum vanadium and the copper, and before welding, oil removal, acid pickling and the like are carried out to remove impurities, oxides, oil stains and other impurities on the surface of the thin layer.

6. The welding method of claim 2, wherein the step of welding comprises: and the solder resist material during welding in the step S2 is a spacer which is arranged between the vanadium tantalum and the sheath welding.

7. The welding method of claim 2, wherein the step of welding comprises: and in the step S4, removing the sheath and the excess material by using a mechanical processing method of multiple turning of a small-sized cutter to obtain the composite target formed by welding tantalum, vanadium and a copper block.

8. The welding method of claim 2, wherein the step of welding comprises: and in the step S5, an instrument used for observing the welding interface is a low magnification magnifier.

9. The welding method of claim 2, wherein the step of welding comprises: and in the step S2, in order to prevent the vanadium tantalum from being welded with the sheath, a solder resisting material is adopted to separate the welded object from the metal sheath.

10. The welding method of claim 2, wherein the step of welding comprises: the temperature of the hot isostatic pressing process in step S4 is controlled at 800-1200 degrees celsius.

Technical Field

The invention relates to a material compounding method, in particular to a welding method for realizing the purpose of prolonging the service life of a composite target material by welding and compounding dissimilar metals and the outer layer of a target body.

Background

The Accelerator-Based Boron Neutron Capture Therapy cancer (A-BNCT) device can be installed in a hospital, and has the reaction principle that protons are accelerated to certain energy by the Accelerator and then bombard a target body to form epithermal neutrons after shaping, the extracted epithermal neutrons irradiate tumor cells enriched with 10B, Capture reaction is carried out to generate 1.47MeV alpha particles and high-energy lithium particles to kill the cancer cells, and good treatment effects are produced on recurrent head and neck cancer, malignant brain glioma, melanoma and head and neck tumors.

The BNCT target body composite material is a core component of a boron neutron capture therapeutic instrument, is formed by combining beryllium and oxygen-free copper and is mainly used for generating neutrons. Wherein, beryllium produces the neutron under the bombardment of high-energy proton beam, neutron flux is higher (corresponding thermal deposition can also promote along with it), treatment time is shorter, therefore the massive thermal deposition that produces in the bombardment process needs to be removed in time through the good oxygen-free copper material of thermal conductivity and circulating water. In order to prevent the normal operation of the target body from being influenced by overhigh temperature of the beryllium, the copper block is required to be subjected to heat convection continuously by utilizing high-speed water flow so as to achieve a certain cooling effect. In the process of bombarding the target material and the copper block, protons are gathered in the target material or the copper block, so that the target material is easy to foam and swell, the service life of the target body is further shortened, the neutron yield of the target body is reduced, and the time of boron neutron capture treatment is also prolonged. Therefore, the tantalum or vanadium needs to be connected on the surface of the copper block through a hot isostatic pressing diffusion welding process, and the ultra-thin layer state is achieved by ensuring that the thickness of the tantalum layer or the vanadium layer is smaller as far as possible in consideration of the heat conduction effect. Finally, the vanadium-tantalum layer of the composite target material is welded with copper in a hot isostatic pressing mode through the method, so that protons are deposited in the ultrathin vanadium-tantalum layer, the proton migration capability of the target material is prolonged, the reduction of the heat migration capability is avoided, foaming caused by introduction of welding fluxes by other welding methods is avoided, and the service life of the target body is prolonged.

The welding method for tantalum and copper dissimilar metal diffusion provided by the invention of the patent CN101733544A is to place the welded object into a closed container, make the internal space of the container reach a vacuum state through an air extraction opening arranged in the container, and then realize the connection between metals by using a hot isostatic pressing diffusion welding process. However, there are the following problems:

(1) the shape of the closed container needs to be correspondingly adjusted according to the actual size of the welded object, so that the process complexity is further improved;

(2) in consideration of actual processing conditions, the air pumping hole is difficult to ensure that the inside of the closed container reaches a high vacuum state, so that the diffusion welding quality is influenced;

(3) in the welding method, the welded object is in direct contact with the sheath, and after welding is finished, the diffusion adhesion phenomenon is easy to occur, so that the welding materials are tightly combined and are difficult to separate, and the welding materials can be separated only by subsequent machining or acid treatment and other methods, which generally causes structural damage or damage to the integrity of the welding parts, and the welding requirements are difficult to achieve, and the materials are difficult to effectively recycle.

Disclosure of Invention

The invention aims to provide a welding method for prolonging the service life of a composite target material, and aims to solve the problems that in the prior art, a welded object is in direct contact with a sheath, and after welding is finished, diffusion adhesion is easy to occur, so that welding materials are tightly combined and are difficult to separate.

In order to achieve the purpose, the invention provides the following technical scheme: a welding method for prolonging the service life of a composite target material is characterized in that: the welding method is to weld ultra-thin tantalum and vanadium layers on a copper layer outside a welded target body through a solder resist material.

2. The welding method for enhancing the life of a composite target according to claim 1, wherein: the method comprises the following steps:

s1, processing raw materials, namely cutting a sample from a pure tantalum or vanadium square rod, processing an oxygen-free copper material into a copper block with a specified size and taking the copper block as a welded object, and simultaneously manufacturing a corresponding metal sheath according to the size of the copper block;

s2, assembling parts, namely assembling the tantalum, vanadium and copper blocks into the metal sheath, wherein in the assembling process, the tantalum and vanadium foil sheets are in plane contact with the surface of the copper block;

s3, performing hot isostatic pressure diffusion welding, and welding the sheath by adopting an electron beam to keep the interior of the sheath in a vacuum state;

s4, machining, and placing the welded sheath into hot isostatic pressing equipment for temperature-controlled diffusion welding;

and S5, detecting the welding quality, and evaluating the welding strength by observing whether the welding interface has defects.

The cutting thickness of the sample in the step S1 is 0.5-1.5mm, and the thicknesses of the tantalum foil and the vanadium foil are processed to 0.1-0.5 mm.

And (3) cleaning the sample in the step S1 by using acetone as a solution, spraying alcohol after cleaning, and finally drying.

And in the assembling process in the step S2, the environment is clean, no polluting substances such as dust, oil stains and the like enter the interface of the tantalum vanadium and the copper, and before welding, oil removal, acid pickling and the like are carried out to remove impurities, oxides, oil stains and other impurities on the surface of the thin layer.

And the solder resist material is a spacer sheet arranged between the vanadium tantalum and the sheath welding during welding in the step S2.

And in the step S4, removing the sheath and the excess material by using a mechanical processing method of multiple turning of a small-sized cutter to obtain the composite target formed by welding tantalum, vanadium and a copper block.

And in the step S5, an instrument used for observing the welding interface is a low magnification magnifier.

And in the step S2, in order to prevent the vanadium tantalum from being welded with the sheath, a solder resisting material is adopted to separate the welded object from the metal sheath.

The temperature of the hot isostatic pressing process in step S4 is controlled at 800-1200 degrees celsius.

In order to enable the person to visually check the welding quality, it is preferable that the instrument used for observing the welding interface in the step S5 is a low magnification magnifier.

Compared with the prior art, the invention has the beneficial effects that:

1) welding by adopting a hot isostatic pressing diffusion welding method, and ensuring that the tantalum foil after welding has no wrinkles and deformation;

2) and the welding of the sheath and the tantalum sheet is prevented by adopting a solder resist material, and the surface of the tantalum foil is not required to be processed when the sheath is detached, so that the thickness of the tantalum foil is ensured to meet the technical requirement, and the yield of the composite target product is improved.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is a schematic flow diagram of the present invention;

FIG. 2 is an enlarged view of the tantalum-copper interface bond of the present invention;

FIG. 3 is an enlarged view of the vanadium-copper interface bond of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-3, the present invention provides the following technical solutions:

a welding method for prolonging the service life of a composite target material is characterized in that an ultra-thin tantalum layer and an ultra-thin vanadium layer are welded on a copper layer outside a welded target body through a solder resist material.

A welding method for prolonging the service life of a composite target material comprises the following steps:

s1, processing raw materials, namely cutting a sample from a pure tantalum or vanadium square rod by adopting a linear cutting mode, cleaning and drying after polishing to obtain tantalum foil and vanadium foil for later use, processing an oxygen-free copper material into a copper block with a specified size and using the copper block as a welded object, and simultaneously manufacturing a corresponding metal sheath according to the size of the copper block;

s2, assembling the parts, wherein in the process of assembling the parts, the tantalum and the vanadium foil contact with the surface plane of the copper block, and in addition, in order to prevent the vanadium and the tantalum from being welded with the sheath, a solder resisting material is adopted to separate the welded object from the metal sheath;

s3, performing hot isostatic pressure diffusion welding, and welding the sheath by adopting an electron beam to keep the interior of the sheath in a vacuum state;

s4, machining, and placing the welded sheath into hot isostatic pressing equipment for temperature-controlled diffusion welding, wherein the temperature of the hot isostatic pressing process is controlled at 800-1200 ℃, and the optimal scheme is that the temperature is controlled at 900 ℃;

and S5, detecting the welding quality, and evaluating the welding strength by observing whether the welding interface has defects.

In this embodiment: the cutting thickness of the sample in the step S1 is 1mm, the thicknesses of the tantalum foil and the vanadium foil are processed to be 0.03mm, the solution adopted for cleaning the sample in the step S1 is acetone, the acetone is sprayed with alcohol after cleaning, and finally drying treatment is carried out.

Specifically, adopt the wire-electrode cutting to surely get 1mm sample of thickness from pure tantalum or vanadium square bar, adopt carborundum abrasive paper to polish and wait to weld the face to 5000, later adopt 1.5 micron aluminium oxide polishing paste to polish on the burnishing machine, after the polishing treatment, put into acetone with the sample and carry out the ultrasonic cleaning, get rid of surface greasy dirt, oxide and other impurity, spray alcohol after taking out, blow dry for subsequent use, process the thickness of tantalum foil, vanadium foil to 0.03mm, and guarantee that the plane degree of both is better. And processing the oxygen-free copper material into a copper block with a specified size and taking the copper block as a welded object, and simultaneously manufacturing a corresponding metal sheath according to the size of the copper block.

In this embodiment: and in the assembling process in the step S2, the environment is clean, no polluting substances such as dust, oil stain and the like enter the interface of the tantalum vanadium and the copper, oil removal, acid cleaning and the like are carried out before welding, impurities, oxides, oil stains and other impurities on the surface of the thin layer are removed, and the solder resist material is a spacer placed between the vanadium tantalum and the sheath welding in the step S2.

Specifically, in the assembly process of the components, the tantalum foil sheet and the vanadium foil sheet are in plane contact with the surface of the copper block, so that the phenomenon that the fit is influenced by gaps, wrinkles and the like is avoided. Meanwhile, the dry and clean environment in the assembling process is ensured, polluting substances such as dust, oil stain and the like can enter the interface of the tantalum vanadium and the copper, oil removal, acid washing and the like are carried out before welding, impurities, oxides, oil stain and other impurities on the surface of a thin layer are removed, in addition, a spacer is adopted for preventing the vanadium tantalum and the sheath from being welded together for separation, the diffusion adhesion phenomenon between the sheath and a welding part is avoided, and the thickness of the tantalum foil is ensured.

In this embodiment: and S4, removing the sheath and the excess material by using a mechanical processing method of multiple turning of a small-sized cutter to obtain the composite target formed by welding tantalum, vanadium and a copper block.

Specifically, machining is a critical step in the entire manufacturing process, and improper machining easily damages the surfaces of the tantalum layer and the vanadium layer, thereby causing welding failure. And removing the sheath and the excess materials by using a mechanical processing method to obtain the composite target formed by welding the tantalum, the vanadium and the copper block, so that a small-sized cutter is adopted for turning for multiple times during processing, and the tantalum and the vanadium layers can be protected although the processing speed is low and the time consumption is long.

In this embodiment: and in the step S5, the instrument used for observing the welding interface is a low magnification lens.

Specifically, as a diffusion welded part, the welding rate and the welding strength are two key indexes for evaluating the welding quality. The conventional product can be detected through ultrasonic flaw detection and drawing tests, but the thicknesses of a tantalum layer and a vanadium layer in a tantalum vanadium-copper target of BNCT are too thin, only 0.03mm, and the detection capability of the BNCT is far better than that of ultrasonic flaw detection. Other methods such as ray and magnetic powder are not feasible, the ray is difficult to identify when the thickness is too thin, and copper and tantalum vanadium are non-magnetic materials. The industrial CT method is theoretically feasible but is too expensive, so that the welding rate of the welding surface is not an effective nondestructive testing method at present, and the confirmation of the layout quality can be performed only by destructive tests such as metallographic testing. The welding strength is generally tested by a universal tensile testing machine, and the conventional tensile method is not feasible because the tantalum layer is too thin and cannot be processed into a workpiece which can be clamped. The drawing method can be used for detecting the layered composite material, the bonding material and a tensile test rod are bonded together by glue, then a universal tester is used for tensile test, and a sand blower is used for roughening the surface of the material before bonding for ensuring the bonding quality. The vanadium layer of the tantalum layer is too thin, so that the vanadium layer is easily damaged during sand blowing, and the method is not suitable. It is more appropriate to evaluate the welding strength by observing whether the welding interface has defects through a low magnification magnifier.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.