Tungsten-zirconium hot isostatic pressure diffusion welding method

Abstract

The invention provides a tungsten-zirconium hot isostatic pressure diffusion welding method which comprises the following steps: placing a zirconium material and a tungsten material in a sheath, and degassing the sheath; in the process of heating the sheath, at least two heat preservation points are arranged in front of the final heat preservation point to carry out pressure stabilizing treatment on the sheath; and after degassing treatment is completed, hot isostatic pressing treatment is conducted on the sheath, and diffusion welding is completed after cooling. By means of the method, the problems that the temperature difference of the melting points of the tungsten metal and the zirconium metal is large, the deformation degree difference is large, welding wires for welding the tungsten metal and the zirconium metal are difficult to select, and the welding strength is low can be solved, 100% welding of the tungsten metal and the zirconium metal is achieved, and the welding strength reaches up to 100 MPa or above.

Description

Technical Field

[0001] The invention belongs to the field of target material manufacturing and relates to a tungsten-zirconium hot isostatic pressing diffusion welding method. Background Art

[0002] Hot Isostatic Pressing (HIP) is a process that subjects the workpiece to isostatic pressing under the simultaneous action of high temperature and high pressure. It can achieve the two-step forming and sintering of traditional powder metallurgy processes at the same time.

[0003] Zirconium has strong corrosion resistance and good ductility. Its excellent mechanical properties make it a popular material for core structures in water-cooled nuclear reactors. However, its strength and corrosion resistance do not meet the requirements for nuclear fuel cladding and pressure tubes. Tungsten has poor oxidation resistance but high strength, making it a good match for zirconium. Summary of the Invention

[0004] In order to solve the technical problems existing in the prior art, the present invention provides a tungsten-zirconium hot isostatic pressing diffusion welding method, which can solve the problems of large melting point temperature difference between tungsten and zirconium metals, large difference in deformation degree, difficulty in selecting tungsten-zirconium metal welding wire, low welding strength, etc., and achieve 100% welding of tungsten and zirconium metals with a welding strength of more than 100MPa.

[0005] In order to achieve the above technical effects, the present invention adopts the following technical solutions:

[0006] The present invention provides a tungsten-zirconium hot isostatic pressing diffusion welding method, which comprises the following steps:

[0007] Place the zirconium and tungsten materials in a package and degas the package;

[0008] During the heating process of the package, at least two insulation points are set before the final insulation point to stabilize the pressure of the package;

[0009] After the degassing treatment is completed, the package is hot isostatically pressed and diffusion welded after cooling.

[0010] As a preferred technical solution of the present invention, 3 to 5 insulation points are set before the final insulation point for voltage stabilization.

[0011] As the preferred technical solution of the present invention, the vacuum degree of the pressure stabilization treatment is 3 to 5×10 -3 Pa.

[0012] As a preferred technical solution of the present invention, the heating temperature rising rate is 3-5°C / min.

[0013] As a preferred technical solution of the present invention, the temperature of the degassing treatment is the final heat preservation point, and the temperature of the final heat preservation point is 500 - 800 °C.

[0014] As a preferred technical solution of the present invention, the vacuum degree of the degassing treatment is 3 - 5×10 -3 Pa.

[0015] As a preferred technical solution of the present invention, the time of the degassing treatment is 10 - 24 h.

[0016] As a preferred technical solution of the present invention, the temperature of the hot isostatic pressing treatment is 700 - 1000 °C.

[0017] As a preferred technical solution of the present invention, the pressure of the hot isostatic pressing treatment is 80 - 130 MPa.

[0018] As a preferred technical solution of the present invention, the time of the hot isostatic pressing treatment is 3 - 7 h.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects:

[0020] The present invention provides a tungsten-zirconium hot isostatic pressing diffusion welding method, which can solve the problems of large melting point temperature difference between tungsten and zirconium, large deformation degree difference, difficult selection of welding wire for tungsten-zirconium metal welding, low welding strength, etc., and realize 100% welding of tungsten-zirconium metal, and the welding strength is up to more than 100 MPa. Brief Description of the Drawings

[0021] Figure 1 Schematic flow chart of the tungsten-zirconium hot isostatic pressing diffusion welding method provided by the present invention.

[0022] The following further describes the present invention in detail. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the patent protection of the present invention. The scope of protection of the present invention shall be subject to the claims. Detailed Embodiments

[0023] The technical solution of the present application will be further described below through specific embodiments.

[0024] The detailed embodiments of the present invention provide a tungsten-zirconium hot isostatic pressing diffusion welding method, which includes the following steps:

[0025] Place zirconium material and tungsten material in a jacket, and perform degassing treatment on the jacket;

[0026] During the process of heating and raising the temperature of the jacket, at least 2 heat preservation points are set before the final heat preservation point to perform voltage stabilization treatment on the jacket;

[0027] After the degassing treatment is completed, perform hot isostatic pressing treatment on the jacket, and complete diffusion welding after cooling.

[0028] In the present invention, since the degassing treatment needs to be carried out at high temperature, and the difference in the thermal expansion coefficients of tungsten and zirconium is large, thermal stress is likely to be generated at the contact surface during the heating process, resulting in the generation of microcracks, gas residue, and incomplete degassing treatment. At the same time, due to the oxidation sensitivity of zirconium, it is prone to react with oxygen during the heating process, thus affecting the diffusion welding effect. Therefore, in this method, multiple heat preservation points are set during the degassing treatment for pressure stabilization. On the one hand, it can avoid the accumulation of thermal stress caused by continuous heating and release the thermal stress generated during the previous heating process, avoiding the generation of microcracks; on the other hand, it can also reduce the heat preservation time at the final heat preservation point, reduce the reaction risk between zirconium and oxygen, and further improve the diffusion welding effect.

[0029] In a specific embodiment of the present invention, 3 to 5 heat preservation points are set for pressure stabilization before the final heat preservation point.

[0030] In a specific embodiment of the present invention, starting from the first heat preservation point, the heat preservation points are set at equal temperature intervals.

[0031] In a specific embodiment of the present invention, the heating rate between each heat preservation point is the same.

[0032] In a specific embodiment of the present invention, if the temperature of the final heat preservation point is 600 °C, the setting method of each heat preservation point can be 100 °C, 200 °C, 300 °C, 400 °C, 500 °C, and 600 °C.

[0033] In a specific embodiment of the present invention, the vacuum degree for pressure stabilization is 3 to 5×10 -3 Pa, such as 3×10 -3 Pa, 3.5×10 -3 Pa, 4×10 -3 Pa, 4.5×10 -3 Pa, or 5×10 -3 Pa, etc., but not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0034] In a specific embodiment of the present invention, the heating rate for heating up is 3 to 5 °C / min, such as 3 °C / min, 3.5 °C / min, 4 °C / min, 4.5 °C / min, or 5 °C / min, etc., but not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0035] In a specific embodiment of the present invention, the temperature for degassing treatment is the final heat preservation point, and the temperature of the final heat preservation point is 500 to 800 °C, such as 500 °C, 550 °C,

[0036] In a specific embodiment of the present invention, the degree of vacuum for degassing treatment is 3 - 5×10 -3 Pa, such as 3×10 -3 Pa, 3.5×10 -3 Pa, 4×10 -3 Pa, 4.5×10 -3 Pa or 5×10 -3 Pa, etc., but not limited to the listed values. Other unlisted values within this numerical range are also applicable.

[0037] In a specific embodiment of the present invention, the time for degassing treatment is 10 - 24 h, such as 10 h, 12 h, 15 h, 18 h, 20 h or 24 h, etc., but not limited to the listed values. Other unlisted values within this numerical range are also applicable.

[0038] In a specific embodiment of the present invention, the cladding is preferably a stainless - steel cladding.

[0039] In a specific embodiment of the present invention, a high - temperature - resistant material is used to separate the cladding from the zirconium material and the tungsten material. Among them, the high - temperature - resistant material used is a material commonly used in hot isostatic pressing treatment, and no specific limitation is made here.

[0040] In a specific embodiment of the present invention, after the zirconium material and the tungsten material are loaded into the cladding, the cladding is hermetically sealed by argon arc welding, and a degassing pipe is connected (such as by welding, etc.) to the cladding.

[0041] In a specific embodiment of the present invention, the zirconium material and the tungsten material are surface - treated before being transferred into the cladding.

[0042] In a specific embodiment of the present invention, the surface treatment can be grinding, polishing and cleaning carried out in sequence.

[0043] In a specific embodiment of the present invention, the specific process of the surface treatment can be: using a grinding machine to grind the surface of the raw material, and after the grinding is completed, polishing treatment is carried out until the surface grinding marks disappear. Subsequently, the surface is cleaned successively with a mixed solution of hydrochloric acid and nitric acid, anhydrous ethanol, and deionized water to remove surface oil stains and oxide layers.

[0044] In a specific embodiment of the present invention, the temperature of the hot isostatic pressing treatment is 700 - 1000 °C, such as 700 °C, 750 °C, 800 °C, 850 °C, 900 °C, 950 °C or 1000 °C, etc., but not limited to the listed values. Other unlisted values within this numerical range are also applicable.

[0045] In a specific embodiment of the present invention, the pressure of hot isostatic pressing treatment is 80 to 130 MPa, such as 80 MPa, 85 MPa, 90 MPa, 95 MPa, 100 MPa, 105 MPa, 110 MPa, 115 MPa, 120 MPa, 125 MPa or 130 MPa, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0046] In a specific embodiment of the present invention, the time of hot isostatic pressing treatment is 3 to 7 h, such as 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h, 6.5 h or 7 h, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0047] In a specific embodiment of the present invention, the product after hot isostatic pressing treatment is cooled with the furnace.

[0048] In a specific embodiment of the present invention, after cooling, the jacket is removed, for example, by plasma cutting, to obtain a welded sample.

[0049] In a specific embodiment of the present invention, the welded sample is machined and processed, etc., to obtain a target with the required thickness and shape.

[0050] To better illustrate the present invention and facilitate understanding of its technical solution, the typical but non-limiting embodiments of the present invention are as follows:

[0051] Example 1

[0052] This example provides a tungsten-zirconium hot isostatic pressing diffusion welding method, and its process is as Figure 1 shown, and this method includes the following steps:

[0053] Place zirconium material and tungsten material in a stainless steel jacket, separate the jacket from the zirconium material and tungsten material with a high-temperature resistant material, use argon arc welding to seal the jacket and weld the degassing pipe, place the jacket in a degassing furnace, heat the jacket at 5 °C / min, and perform pressure stabilization treatment at 100 °C, 200 °C, 300 °C, 400 °C and 500 °C in sequence, so that the vacuum degree is stabilized at 3 - 5×10 -3 Pa and then raise the temperature, keep the temperature at 600 °C for 15 h for degassing treatment, and the vacuum degree is 3 - 5×10 -3 Pa;

[0054] After the degassing treatment is completed, place the jacket in a hot isostatic press for hot isostatic pressing treatment. The temperature of the hot isostatic pressing treatment is 800 °C, the pressure is 110 MPa, the time is 5 h, after cooling with the furnace, use plasma cutting to remove the jacket to obtain a zirconium-tungsten welded sample.

[0055] Example 2

[0056] This embodiment provides a tungsten-zirconium hot isostatic pressing diffusion welding method, which includes the following steps:

[0057] Place the zirconium material and tungsten material in a stainless steel jacket, separate the jacket from the zirconium material and tungsten material using a high-temperature resistant material, seal the jacket and weld the degassing pipe using argon arc welding, place the jacket in a degassing furnace, heat the jacket at 3 °C / min, and perform pressure stabilization treatment at 100 °C, 200 °C, 300 °C, 400 °C, and 500 °C in sequence to make the vacuum degree stable at 3 - 5×10 -3 Pa, then raise the temperature, keep it at 600 °C for 15 h for degassing treatment, and the vacuum degree is 3 - 5×10 -3 Pa;

[0058] After the degassing treatment is completed, place the jacket in a hot isostatic press for hot isostatic pressing treatment. The temperature of the hot isostatic pressing treatment is 700 °C, the pressure is 130 MPa, and the time is 7 h. After cooling with the furnace, use plasma cutting to remove the jacket to obtain a zirconium-tungsten welded sample.

[0059] Example 3

[0060] This embodiment provides a tungsten-zirconium hot isostatic pressing diffusion welding method, which includes the following steps:

[0061] Place the zirconium material and tungsten material in a stainless steel jacket, separate the jacket from the zirconium material and tungsten material using a high-temperature resistant material, seal the jacket and weld the degassing pipe using argon arc welding, place the jacket in a degassing furnace, heat the jacket at 4 °C / min, and perform pressure stabilization treatment at 100 °C, 200 °C, 300 °C, 400 °C, and 500 °C in sequence to make the vacuum degree stable at 3 - 5×10 -3 Pa, then raise the temperature, keep it at 600 °C for 15 h for degassing treatment, and the vacuum degree is 3 - 5×10 -3 Pa;

[0062] After the degassing treatment is completed, place the jacket in a hot isostatic press for hot isostatic pressing treatment. The temperature of the hot isostatic pressing treatment is 1000 °C, the pressure is 80 MPa, and the time is 3 h. After cooling with the furnace, use plasma cutting to remove the jacket to obtain a zirconium-tungsten welded sample.

[0063] Example 4

[0064] This embodiment provides a tungsten-zirconium hot isostatic pressing diffusion welding method, which includes the following steps:

[0065] Place zirconium and tungsten materials in a stainless-steel sheath, separate the sheath from the zirconium and tungsten materials using high-temperature-resistant materials, seal the sheath by argon arc welding and weld the degassing pipe, place the sheath in a degassing furnace, heat the sheath at 5 °C / min, and perform pressure stabilization treatment at 100 °C, 200 °C, 300 °C and 400 °C in sequence to stabilize the vacuum degree at 3 - 5×10 -3 Pa, then raise the temperature, hold at 500 °C for 24 h for degassing treatment, and the vacuum degree is 3 - 5×10 -3 Pa;

[0066] The degassing treatment is the same as that in Example 1.

[0067] Example 5

[0068] This example provides a tungsten-zirconium hot isostatic pressing diffusion welding method, and this method includes the following steps:

[0069] Place zirconium and tungsten materials in a stainless-steel sheath, separate the sheath from the zirconium and tungsten materials using high-temperature-resistant materials, seal the sheath by argon arc welding and weld the degassing pipe, place the sheath in a degassing furnace, heat the sheath at 3 °C / min, and perform pressure stabilization treatment at 100 °C, 250 °C, 400 °C and 550 °C in sequence to stabilize the vacuum degree at 3 - 5×10 -3 Pa, then raise the temperature, hold at 700 °C for 12 h for degassing treatment, and the vacuum degree is 3 - 5×10 -3 Pa;

[0070] The degassing treatment is the same as that in Example 1.

[0071] Example 6

[0072] This example provides a tungsten-zirconium hot isostatic pressing diffusion welding method, and this method includes the following steps:

[0073] Place zirconium and tungsten materials in a stainless-steel sheath, separate the sheath from the zirconium and tungsten materials using high-temperature-resistant materials, seal the sheath by argon arc welding and weld the degassing pipe, place the sheath in a degassing furnace, heat the sheath at 4 °C / min, and perform pressure stabilization treatment at 200 °C, 400 °C and 600 °C in sequence to stabilize the vacuum degree at 3 - 5×10 -3 Pa, then raise the temperature, hold at 800 °C for 10 h for degassing treatment, and the vacuum degree is 3 - 5×10 -3 Pa;

[0074] The degassing treatment is the same as that in Example 1.

[0075] Comparative Example 1

[0076] In this comparative example, except that no other holding points are set for pressure stabilization before the final holding point, that is, the jacket is directly heated to 600 °C at 5 °C / min for degassing treatment, the other conditions are the same as those in Example 1.

[0077] Comparative Example 2

[0078] In this comparative example, except that only 1 holding point is set for pressure stabilization before the final holding point, that is, the jacket is directly heated to 300 °C at 5 °C / min to stabilize the vacuum degree at 3-5×10 -3 Pa and then heated to 600 °C for degassing treatment, the other conditions are the same as those in Example 1.

[0079] Tungsten blocks and zirconium blocks with a size of 100 mm×100 mm×12 mm and a purity of 99.95% are used in Examples 1-6 and Comparative Examples 1-2. Before being loaded into the jacket, the tungsten blocks and zirconium blocks are surface-treated. Specifically, the surfaces of the zirconium blocks and tungsten blocks are polished using a grinding machine. After grinding, they are polished until the surface grinding marks disappear. Subsequently, they are successively cleaned with a mixed solution of hydrochloric acid and nitric acid, anhydrous ethanol, and deionized water to remove surface oil stains and oxide layers.

[0080] The welding strength and bonding rate of the welding surfaces of the zirconium-tungsten welding samples provided in Examples 1-6 and Comparative Examples 1-2 are tested. The results are shown in Table 1. Among them, the welding strength is tested using a universal testing machine, and the bonding rate is tested using an ultrasonic flaw detector.

[0081] Table 1

[0082]

[0083]

[0084] It can be seen from the test results in Table 1 that the welding strength of the zirconium-tungsten welding samples prepared in Examples 1-6 is above 70 MPa, and the bonding rate can reach 100%. The setting of the holding points during the degassing treatment will affect the degassing effect and the final welding effect. In Comparative Example 1, no holding point was set for pressure stabilization, but it was directly heated to the degassing temperature, resulting in a decrease in the bonding rate and welding strength. Although 1 holding point was set for pressure stabilization in Comparative Example 2, the effect could not reach the level of Example 1, and both the bonding rate and welding strength were lower than those in Example 1.

[0085] The applicant declares that the detailed structural features of the present invention are illustrated by the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of the components selected for the present invention, the addition of auxiliary components, and the selection of specific methods, etc., all fall within the protection scope and the disclosure scope of the present invention.

[0086] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept scope of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0087] In addition, it should be noted that, among the various specific technical features described in the above specific embodiments, without contradiction, they can be combined in any appropriate manner. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0088] In addition, any combination can be made among various different embodiments of the present invention, as long as it does not violate the idea of the present invention, it should also be regarded as the content disclosed by the present invention.

Claims

1. A tungsten-zirconium hot isostatic pressing diffusion welding method, characterized in that, The method includes the following steps: Place zirconium material and tungsten material in a jacket, and degas the jacket; During the process of heating up the jacket, at least two holding points are set before the final holding point to perform pressure stabilization treatment on the jacket; After the degassing treatment is completed, perform hot isostatic pressing on the jacket, and complete the diffusion welding after cooling.

2. The tungsten-zirconium hot isostatic pressing diffusion welding method according to claim 1, wherein Three to five holding points are set before the final holding point for pressure stabilization treatment.

3. The tungsten-zirconium hot isostatic pressing diffusion welding method according to claim 1, characterized in that The degree of vacuum for the voltage stabilization treatment is 3 to 5×10 -3 Pa.

4. The tungsten-zirconium hot isostatic pressing diffusion welding method according to claim 1, wherein The heating rate is 3 - 5 °C / min.

5. The tungsten-zirconium hot isostatic pressing diffusion welding method according to claim 1, characterized in that, The temperature of the degassing treatment is the final holding point, and the temperature of the final holding point is 500 - 800 °C.

6. The tungsten-zirconium hot isostatic pressing diffusion welding method according to claim 1, characterized in that, The degree of vacuum for the degassing treatment is 3 to 5×10 -3 Pa.

7. The tungsten-zirconium hot isostatic pressing diffusion welding method according to claim 1, characterized in that, The time of the degassing treatment is 10 - 24 h.

8. The tungsten-zirconium hot isostatic pressing diffusion welding method according to claim 1, characterized in that, The temperature of the hot isostatic pressing treatment is 700 - 1000 °C.

9. The tungsten-zirconium hot isostatic pressing diffusion welding method according to claim 1, wherein, The pressure of the hot isostatic pressing treatment is 80 - 130 MPa.

10. The tungsten-zirconium hot isostatic pressing diffusion welding method according to claim 1, characterized in that, The time of the hot isostatic pressing treatment is 3 - 7 h.

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