Method for manufacturing cryogenic getter pump

Abstract

The present invention relates to a low-temperature getter pump and a manufacturing method thereof, wherein the low-temperature getter pump comprises a low-temperature agent circulation pipeline, in which the low-temperature agent is circulated internally; a knife-edge flange, which is sleeved outside the low-temperature agent circulation pipeline and is tightly matched with or fixedly connected to the low-temperature agent circulation pipeline; an adsorption assembly, wherein a plurality of adsorption assemblies are respectively sleeved outside the low-temperature agent circulation pipeline above the knife-edge flange and are tightly matched with the low-temperature agent circulation pipeline, and the plurality of adsorption assemblies are arranged at intervals along the length direction of the low-temperature agent circulation pipeline; a first metal gasket, which is respectively provided between the bottommost adsorption assembly and the knife-edge flange and between adjacent adsorption assemblies; a limiter, which is cooperatively connected with the upper end of the low-temperature agent circulation pipeline to press the adsorption assembly and prevent it from falling.

Description

Technical Field

[0001] The invention relates to the field of vacuum technology, and in particular to a method for manufacturing a low-temperature getter pump. Background Art

[0002] Heavy ion accelerators are important tools for studying the structure of atomic nuclei, nuclear reaction mechanisms, nuclear processes in the evolution of the universe, and frontier scientific and technological issues related to heavy ions. With the continuous expansion of its application fields, the limits of heavy ion accelerators for high energy, high current intensity, and high bunch power are constantly improving. Superconducting accelerators will be a major direction for the development of heavy ion accelerators in the future. The beam life is related to the amount of residual gas in the vacuum chamber, eddy current effect, and impedance. The collision between ions and residual gas molecules / atoms and the collision between ions and the walls of the vacuum chamber will produce a large amount of gas desorption, thereby triggering a dynamic vacuum effect, that is, a local pressure increase phenomenon, which will greatly affect the beam life. It is well known that the residual gases in ultra-high / ultra-high vacuum systems are mainly hydrogen, carbon monoxide, helium, etc. The cryogenic getter pump has a very considerable pumping speed and saturation capacity for gases that are difficult to condense, such as hydrogen and helium. If the system is equipped with a cryogenic getter pump, the gas generated by beam loss can be discharged in time. On the other hand, the cryogenic getter pump is a capture pump, which has no moving parts, simple structure and low cost, and can work in high electric and magnetic field environments. Therefore, it is widely used in superconducting accelerators, metallurgy, chemical industry, semiconductor industry, aerospace, fusion systems and other fields.

[0003] The traditional cryogenic getter pump is mainly composed of four parts: liquid helium circulation pipeline, adsorbent, binder and metal plate. The main function of the liquid helium circulation pipeline is to provide a low temperature environment for the cryogenic adsorption pump. The adsorbent is a porous material, such as activated carbon, molecular sieve, metal sponge, zeolite, etc., and its main function is to increase the adsorption area. The function of the binder is to bond the adsorbent and the metal plate together. The binder should be easy to apply to the metal plate and have sufficient bonding strength. At the same time, it can still stick the adsorbent such as activated carbon to the metal plate after multiple thermal cycles. The commonly used binder is epoxy resin or epoxy resin with high thermal conductivity metal powder added. The main function of the metal plate is to provide a bed space for the adsorbent, which is mainly made of high thermal conductivity materials such as oxygen-free copper.

[0004] The cryogenic getter pump made by the traditional manufacturing method uses an organic binder to bond the adsorbent material to the metal plate. However, the organic binder has a high outgassing rate at room temperature, which will have an adverse effect on the vacuum degree of the system. Furthermore, the organic binder has a low thermal conductivity, which affects the pumping rate of the cryogenic getter pump. Furthermore, the organic binder will gradually age over time, causing the adsorbent material to fall off, reducing the pumping speed and causing pollution. Summary of the invention

[0005] In view of the above problems, the purpose of the present invention is to provide a method for manufacturing a low-temperature getter pump, which utilizes indium solder and an intermediate coating to bond activated carbon rods or other getter materials to a metal plate through an organic binder-free bonding technology, thereby reducing the surface outgassing rate of traditional adhesives at room temperature, avoiding the shedding of adsorbents such as activated carbon caused by aging of organic adhesives, and solving the problem of pumping speed loss caused by low thermal conductivity.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The cryogenic getter pump of the present invention comprises: a cryogenic agent circulation pipeline, in which the cryogenic agent is circulated;

[0008] A knife-edge flange, which is sleeved outside the cryogenic preparation circulation pipeline and is tightly matched or fixedly connected to the cryogenic preparation circulation pipeline; an adsorption assembly, wherein a plurality of adsorption assemblies are respectively sleeved outside the cryogenic preparation circulation pipeline above the knife-edge flange and are tightly matched to the cryogenic preparation circulation pipeline, and a plurality of the adsorption assemblies are arranged at intervals along the length direction of the cryogenic preparation circulation pipeline; a first metal gasket, wherein the first metal gasket is respectively arranged between the bottommost adsorption assembly and the knife-edge flange and between adjacent adsorption assemblies; a stopper, which is matched and connected to the upper end of the cryogenic preparation circulation pipeline to compress the adsorption assembly and prevent it from falling;

[0009] Among them, the adsorption assembly includes a metal plate and an activated carbon rod; the metal plate is in the shape of a disk with a circular hole in the center; the metal plate is sleeved outside the low-temperature agent circulation pipeline, and a plurality of grooves are respectively provided on its upper and lower surfaces; a plurality of the activated carbon rods are fixed in the grooves by using an organic binder-free bonding technology; the organic binder-free bonding technology is to use indium solder and the intermediate coating on the activated carbon rod for welding.

[0010] The cryogenic getter pump, preferably, the cryogenic preparation circulation pipeline includes a cryogenic preparation circulation inlet pipe and a cryogenic preparation circulation outlet pipe; the cryogenic preparation circulation inlet pipe is a pipe structure with openings at both upper and lower ends, wherein the lower end opening is the cryogenic preparation inlet; the cryogenic preparation circulation outlet pipe is a pipe structure with closed upper and lower ends, the cryogenic preparation circulation outlet pipe is sleeved outside the cryogenic preparation circulation inlet pipe, and a cryogenic preparation outlet is provided on one side; the upper end opening of the cryogenic preparation circulation inlet pipe leaves a set distance from the upper end face of the cryogenic preparation circulation outlet pipe, and its lower end extends out of the lower end face of the cryogenic preparation circulation outlet pipe by a set distance.

[0011] In the low-temperature getter pump, preferably, the activated carbon rod is plated with a double-layer film of pure Ti and pure Ag.

[0012] The cryogenic getter pump preferably further comprises an indium sheet, which is wound around the cryogenic agent circulation pipeline and is located between the cryogenic agent circulation pipeline and the adsorption assembly.

[0013] The cryogenic getter pump preferably further comprises a second metal gasket, and the second metal gasket is arranged between the limiter and the uppermost adsorption assembly.

[0014] For the cryogenic getter pump, preferably, the first metal gasket and the second metal gasket are respectively made of oxygen-free copper material.

[0015] The method for manufacturing the cryogenic getter pump of the present invention is characterized by comprising the following steps:

[0016] Process the knife-edge flange by CNC machine tools according to the knife-edge flange size;

[0017] Select metal sheets and metal pipes with good thermal conductivity, and perform high-temperature dehydrogenation on the metal sheets, metal pipes and processed knife-edge flanges;

[0018] Processing metal sheets with good thermal conductivity into metal plates of adsorption assemblies, and processing metal pipes with good thermal conductivity into low-temperature agent circulation pipelines;

[0019] Select activated carbon raw materials to process activated carbon rods to form adsorption assemblies, and plate Ti and Ag on the activated carbon rods;

[0020] The activated carbon rod is welded to the metal plate by metal indium brazing to form an adsorption assembly;

[0021] The low-temperature agent circulation pipeline and the knife-edge flange are welded by brazing, wherein the solder is silver-based solder;

[0022] Assemble the adsorption assembly and the knife-edge flange, install the first metal gasket and the stopper at the corresponding position of the low-temperature agent circulation pipeline, and install the second metal gasket between the stopper and the uppermost adsorption assembly;

[0023] The helium mass spectrometry leak detection method is used to detect leaks on the knife edge of the knife edge flange and the weld between the knife edge flange and the cryogenic agent circulation pipeline. If the leakage rate value is less than the set value, it is considered qualified. At the same time, the cryogenic agent circulation pipeline is leak-tested by pressure.

[0024] The manufacturing method, preferably, the high-temperature dehydrogenation of the metal sheet, the metal tube and the processed knife-edge flange specifically comprises the following steps:

[0025] Put the metal sheets, metal tubes and processed blade flanges into a vacuum furnace and place them in a vacuum furnace better than 1×10 -3 Under the conditions of Pa, the degassing temperature is 700-900℃, and the degassing time is 1h / mm wall thickness. High-temperature dehydrogenation is carried out. The dehydrogenation process includes a heating process, a heat preservation process and a cooling process. During the cooling process, the temperature zone of 900-600℃ must be quickly avoided to avoid the formation of carbide precipitation.

[0026] The manufacturing method, preferably, the activated carbon rods selected from the activated carbon raw materials to form the adsorption assembly specifically include the following steps:

[0027] Selecting a raw material suitable for making activated carbon, wherein the raw material is wood, coal or coconut shell, and crushing and screening the raw material to obtain activated carbon particles suitable for making activated carbon;

[0028] The activated carbon particles are mixed evenly with a binder, an activator and an activator co-activator, and then extruded on a twin-screw extruder to obtain a molding material with a specific diameter;

[0029] After the molding material is dried, dehydrated and activated, columnar activated carbon is initially obtained;

[0030] The columnar activated carbon is subjected to the steps of primary water washing, acid washing, secondary water washing and drying to obtain the final activated carbon rod.

[0031] The manufacturing method, preferably, the plating of Ti and Ag on the activated carbon rod specifically comprises the following steps:

[0032] Use high temperature resistant tape or specific tooling to cover the part of the activated carbon rod where no film is to be deposited;

[0033] When the vacuum in the coating chamber of the multi-target DC planar magnetron sputtering coating machine is better than 1×10 -3 Pa, baking was performed at 180 °C for 2 h to activate the surface of the activated carbon and make it have better adhesion;

[0034] 100-120 sccm of high-purity helium is introduced into the coating chamber of the multi-target DC planar magnetron sputtering coating machine to maintain the working pressure of the coating chamber at 0.19-0.23 Pa, the ion source voltage is set to 1500-2000 V, and the surface of the activated carbon rod is cleaned for 10-20 minutes;

[0035] The vacuum angle of the vacuum unit was adjusted to 30-50° to ensure a working gas pressure of 0.23-0.3 Pa, and then the cylindrical Ti target current was set to 10-15 A to deposit the titanium film for 0.5-1 h;

[0036] After the titanium film deposition is completed, the cylindrical Ti target is turned off, and the planar Ag target is turned on. The planar Ag target current is set to 5 to 7 A, and the titanium film is deposited for 2 to 3 hours.

[0037] The manufacturing method, preferably, comprises welding the activated carbon rod to the metal plate by metal indium brazing, which specifically comprises the following steps:

[0038] Introduce Metal 100 or In 97 The Ag3 film is laid flat on the processed metal plate, and the activated carbon rod with titanium film and silver film deposited is placed on the paved metal In 100 or In 97 On the Ag3 film, the metal In 100 or In 97 The Ag3 solder melts and the heating temperature is 160°C to 180°C, thereby completing the welding of the activated carbon rod and the metal plate.

[0039] The present invention adopts the above technical solution, which has the following advantages:

[0040] (1) The getter material is bonded to the metal plate by indium solder and Ti and Ag layers deposited on the surface of activated carbon by magnetron sputtering through a non-organic binder technology. The low-temperature getter pump made by this method can greatly reduce the surface outgassing rate of traditional organic adhesives at room temperature, avoid the aging of organic adhesives and cause the activated carbon and other adsorbents to fall off, and solve the problem of pumping speed loss caused by low thermal conductivity;

[0041] (2) The cryogenic getter pump made by this method has a very impressive pumping speed for gases that are difficult to condense, such as hydrogen and helium, so the gas generated by beam loss can be discharged in a timely manner;

[0042] (3) The cryogenic getter pump is a capture pump with no moving parts, simple structure and low cost, and can work in high electric and magnetic field environments. It will play a positive role in the construction of superconducting accelerators in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Throughout the accompanying drawings, the same reference numerals are used to represent the same components. In the accompanying drawings:

[0044] Figure 1 is a flow chart of manufacturing the cryogenic getter pump of the present invention;

[0045] Figure 2 is a schematic structural diagram of the cryogenic getter pump of the present invention;

[0046] Figure 3 yes Figure 2 A magnified schematic diagram of part A in FIG.

[0047] Figure 4 It is a schematic diagram of the top view of the adsorption assembly in the present invention;

[0048] Figure 5 It is a partially enlarged structural cross-sectional view of the adsorption assembly in the present invention.

[0049] The symbols in the accompanying drawings are as follows:

[0050] 1-low temperature agent circulation inlet pipe; 2-low temperature agent circulation outlet pipe; 3-knife edge flange; 4-first metal gasket; 5-adsorption assembly; 6-second metal gasket; 7-limiting piece; 8-indium sheet; 9-activated carbon rod; 10-metal plate; DETAILED DESCRIPTION

[0051] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0052] The present invention provides a low-temperature getter pump and a manufacturing method thereof. The getter material is bonded to a metal plate by indium solder and a Ti layer and an Ag layer deposited on the surface of activated carbon based on a magnetron sputtering method through an organic binder-free technology, and specific components are processed according to drawings through conventional technical means such as machining and brazing. The present invention can reduce the surface outgassing rate of traditional adhesives at room temperature, avoid the shedding of adsorbents such as activated carbon caused by aging of organic adhesives, and solve the problem of pumping speed loss caused by low thermal conductivity.

[0053] like Figure 2 As shown, the cryogenic getter pump provided by the present invention comprises: a cryogenic agent circulation pipeline, in which a cryogenic agent (the cryogenic agent can be liquid helium) is circulated internally; a knife-edge flange 3, which is sleeved outside the cryogenic agent circulation pipeline and is tightly matched or fixedly connected to the cryogenic agent circulation pipeline; an adsorption assembly 5, wherein a plurality of adsorption assemblies 5 are respectively sleeved outside the cryogenic agent circulation pipeline above the knife-edge flange 3 and are tightly matched to the cryogenic agent circulation pipeline, and the plurality of adsorption assemblies 5 are arranged at intervals along the length direction of the cryogenic agent circulation pipeline; a first metal gasket 4, wherein the first metal gasket 4 is respectively arranged between the bottommost adsorption assembly 5 and the knife-edge flange 3 and between adjacent adsorption assemblies 5; a stopper 7, which is matched and connected with the upper end of the cryogenic agent circulation pipeline to press the adsorption assembly 5 and prevent it from falling, wherein the stopper 7 can be a nut, specifically, a thread is provided on the upper end of the cryogenic agent circulation pipeline, and the nut is matched and connected with the thread;

[0054] Among them, Figure 4 and Figure 5 As shown, the adsorption assembly 5 includes a metal plate 10 and an activated carbon rod 9; the metal plate 10 is in the shape of a disk with a circular hole in the center; the metal plate 10 is sleeved outside the low-temperature agent circulation pipeline, and a plurality of grooves are respectively provided on the upper and lower surfaces thereof, and the plurality of grooves are circumferentially arranged around the circular hole of the metal plate 10; a plurality of activated carbon rods 9 are fixed in the grooves by using an organic binder-free bonding technology; the organic binder-free bonding technology is to use indium solder and an intermediate coating on the activated carbon rod for welding, wherein the intermediate layer is Ti and Ag plated on the Mars carbon rod.

[0055] In the above embodiment, preferably, the cryogenic preparation circulation pipeline includes a cryogenic preparation circulation inlet pipe 1 and a cryogenic preparation circulation outlet pipe 2; the cryogenic preparation circulation inlet pipe 1 is a pipe structure with openings at both ends, wherein the lower end opening is the cryogenic preparation inlet; the cryogenic preparation circulation outlet pipe 2 is a pipe structure with closed ends, the cryogenic preparation circulation outlet pipe 2 is sleeved outside the cryogenic preparation circulation inlet pipe 1, and a cryogenic preparation outlet is provided on one side; the upper end opening of the cryogenic preparation circulation inlet pipe 1 is at a set distance from the upper end face of the cryogenic preparation circulation outlet pipe 2, and its lower end extends out of the lower end face of the cryogenic preparation circulation outlet pipe 2 by a set distance, and a set distance is reserved between the outer wall of the cryogenic preparation circulation inlet pipe 1 and the inner wall of the cryogenic preparation circulation outlet pipe.

[0056] In the above embodiment, preferably, the activated carbon rod is plated with a double-layer thin film of pure Ti and pure Ag.

[0057] In the above embodiment, preferably, Figure 3 As shown, the present invention also includes an indium sheet 8, which is wound outside the cryogenic agent circulation pipeline and is located between the cryogenic agent circulation pipeline and the adsorption assembly, specifically, wound outside the cryogenic agent circulation outlet pipe 2, wherein the indium sheet can be a narrow strip or an integral sheet structure.

[0058] In the above embodiment, preferably, the present invention further comprises a second metal gasket 6 , and the second metal gasket 6 is arranged between the stopper 7 (nut) and the uppermost adsorption assembly 5 .

[0059] In the above embodiment, preferably, the first metal gasket 4 and the second metal gasket 6 are respectively made of oxygen-free copper material.

[0060] like Figure 1 As shown, the manufacturing method of the cryogenic getter pump provided by the present invention comprises the following steps:

[0061] S1. Process the knife-edge flange by CNC machine tools according to the knife-edge flange size;

[0062] S2. Select metal sheets and metal pipes with good thermal conductivity, and perform high-temperature dehydrogenation on the metal sheets, metal pipes and processed knife-edge flanges;

[0063] S3, processing the metal sheet material with good thermal conductivity into the metal plate of the adsorption assembly, and processing the metal pipe material with good thermal conductivity into the low-temperature preparation circulation pipeline;

[0064] S4, selecting activated carbon raw materials to process activated carbon rods to form adsorption assemblies, and coating the activated carbon rods with Ti and Ag;

[0065] S5, welding the activated carbon rod to the metal plate by metal indium brazing to form an adsorption assembly;

[0066] S6. Use brazing to weld the low-temperature agent circulation pipeline and the knife-edge flange, wherein the solder is silver-based solder, such as HL302 or HL309, and the solder paste is 201-F.

[0067] It should be noted that the low-temperature preparation circulation pipeline of the present invention is made of oxygen-free copper, and the knife-edge flange is made of stainless steel. It should be noted that the temperature of the stainless steel side cannot be too high. When heating, the heat source is biased towards the oxygen-free copper side, and the heating temperature is 700°C to 800°C.

[0068] S7, assembling the adsorption assembly and the knife-edge flange, installing the first metal gasket and the stopper at the corresponding position of the low-temperature agent circulation pipeline, and installing the second metal gasket between the stopper and the uppermost adsorption assembly;

[0069] S8. Use helium mass spectrometry to detect leaks on the knife edge of the knife edge flange and the weld between the knife edge flange and the cryogenic agent circulation pipeline, and make the leakage rate value less than 1×10 -8 Pa.ls -1 It is considered qualified and the low-temperature agent circulation pipeline is tested for leaks by pressure testing.

[0070] In the above embodiment, preferably, the high-temperature dehydrogenation of the metal sheet, the metal pipe and the processed knife-edge flange specifically includes the following steps:

[0071] Put the metal sheets, metal tubes and processed blade flanges into a vacuum furnace and place them in a vacuum furnace better than 1×10 - 3 Under the conditions of Pa, the degassing temperature is 700-900℃, and the degassing time is 1h / mm wall thickness. High-temperature dehydrogenation is carried out. The dehydrogenation process includes a heating process, a heat preservation process and a cooling process. During the cooling process, the temperature zone of 900-600℃ must be quickly avoided to avoid the formation of carbide precipitation. Among them, quickly means a time of less than 15 minutes.

[0072] It should be noted that the metal sheets and metal tubes with good thermal conductivity are processed into metal plates and low-temperature preparation circulation pipelines, specifically: the metal plates with good thermal conductivity are finely processed according to the design drawings by machining (CNC machining center) to facilitate the installation of the activated carbon rods after coating; for the processing of the low-temperature preparation circulation pipeline with good thermal conductivity and the processing of the metal plates, more specifically, the metal sheets and metal tubes are first cut, and then the cut metal sheets and metal tubes with different diameters are punched to form metal plates and two pipelines with different diameters (i.e., the low-temperature preparation circulation inlet pipe and the low-temperature preparation circulation outlet pipe), the two pipelines with different diameters are sleeved to form a low-temperature preparation circulation pipeline, and then a handheld laser welding machine is used with a pulse frequency of 2000Hz, a peak power of 400W, and a scanning width of 1.1mm to weld the metal plates and the low-temperature preparation circulation pipeline.

[0073] In the above embodiment, preferably, the activated carbon rods selected from activated carbon raw materials for processing to form the adsorption assembly specifically include the following steps:

[0074] Selecting a raw material suitable for making activated carbon, wherein the raw material is wood, coal or coconut shell, and crushing and screening the raw material to obtain activated carbon particles suitable for making activated carbon;

[0075] The activated carbon particles are mixed evenly with a binder (coal tar, sulfite pulp waste liquid, etc.), an activator (potassium hydroxide, hydrochloric acid, etc.) and an auxiliary activator, and then extruded on a twin-screw extruder to obtain a molding material with a specific diameter;

[0076] After the molding material is dried, dehydrated and activated, columnar activated carbon is initially obtained;

[0077] The columnar activated carbon is subjected to the steps of primary water washing, acid washing, secondary water washing and drying to obtain the final activated carbon rod.

[0078] It should be noted that: the present invention selects coal powder as raw material, and then ball-mills it to less than 100 meshes, selects coal tar tar as binder, selects potassium hydroxide as activator, and mixes them with water and the like, and then extrudes them on a twin-screw extruder to obtain a molding material with a diameter of 2 mm. Further, the heating rate during drying and dehydration is 3-8°C, the nitrogen rate is 80-120ml / min, the dehydration temperature is 350-600°C, the dehydration time is 2-3h, the activation temperature is 650-900°C, and the activation time is 2-3h, thereby preliminarily obtaining columnar activated carbon. Furthermore, water washing, acid washing, secondary water washing, and drying are required to obtain the desired long activated carbon rod.

[0079] In the above embodiment, preferably, the plating of Ti and Ag on the activated carbon rod specifically comprises the following steps:

[0080] Use high temperature resistant tape or specific tooling to cover the part of the activated carbon rod where no film is to be deposited;

[0081] When the vacuum in the coating chamber of the multi-target DC planar magnetron sputtering coating machine is better than 1×10 -3 Pa, baking was performed at 180 °C for 2 h to activate the surface of the activated carbon and make it have better adhesion;

[0082] 100-120 sccm of high-purity helium is introduced into the coating chamber of the multi-target DC planar magnetron sputtering coating machine to maintain the working pressure of the coating chamber at 0.19-0.23 Pa, the ion source voltage is set to 1500-2000 V, and the surface of the activated carbon rod is cleaned for 10-20 minutes;

[0083] The vacuum angle of the vacuum unit was adjusted to 30-50° to ensure a working gas pressure of 0.23-0.3 Pa, and then the cylindrical Ti target current was set to 10-15 A to deposit the titanium film for 0.5-1 h;

[0084] After the titanium film deposition is completed, the cylindrical Ti target is turned off, and the planar Ag target is turned on. The planar Ag target current is set to 5 to 7 A, and the titanium film is deposited for 2 to 3 hours.

[0085] It should be noted that the Ti layer is deposited here because only Ti atoms can grow on the surface of activated carbon, and the Ag layer is deposited because the Ag surface has good wettability and can be well combined with metal In and the metal plate after melting.

[0086] In the above embodiment, preferably, the activated carbon rod is welded to the metal plate by metal indium brazing, which specifically includes the following steps:

[0087] Introduce Metal 100 or In 97 The Ag3 film is laid flat on the processed metal plate, and the activated carbon rod with titanium film and silver film deposited is placed on the paved metal In 100 or In 97 On the Ag3 film, the metal In 100 or In 97 The Ag3 solder melts and the heating temperature is 160°C to 180°C, thereby completing the welding of the activated carbon rod and the metal plate.

[0088] It should be noted that before welding, the metal plate should be cleaned and the oxides and oil stains on the surface should be removed to facilitate the capillary to function after the solder is melted and increase the wettability and capillary fluidity of the solder.

[0089] In addition, the multi-target DC planar magnetron sputtering coating machine, the vacuum unit and the twin-screw extruder in the present invention are all mature components that can be directly purchased on the market and will not be described in detail here.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for manufacturing a cryogenic getter pump, characterized in that: The steps include: Process the knife-edge flange by CNC machine tools according to the knife-edge flange size; Select metal sheets and metal pipes with good thermal conductivity, and perform high-temperature dehydrogenation on the metal sheets, metal pipes and processed knife-edge flanges; Processing metal sheets with good thermal conductivity into metal plates of adsorption assemblies, and processing metal pipes with good thermal conductivity into low-temperature agent circulation pipelines; Select activated carbon raw materials to process activated carbon rods to form adsorption assemblies, and plate Ti and Ag on the activated carbon rods; The activated carbon rod is welded to the metal plate by metal indium brazing to form an adsorption assembly; The low-temperature agent circulation pipeline and the knife-edge flange are welded by brazing, wherein the solder is silver-based solder; Assemble the adsorption assembly and the knife-edge flange, install the first metal gasket and the stopper at the corresponding position of the low-temperature agent circulation pipeline, and install the second metal gasket between the stopper and the uppermost adsorption assembly; The helium mass spectrometry leak detection method is used to detect leaks on the knife edge of the knife edge flange and the weld between the knife edge flange and the cryogenic agent circulation pipeline. If the leakage rate value is less than the set value, it is considered qualified. At the same time, the cryogenic agent circulation pipeline is leak-tested by pressure.

2. The method according to claim 1, characterized in that: The high-temperature dehydrogenation of the metal sheet, the metal pipe and the processed knife-edge flange specifically includes the following steps: Put the metal sheets, metal tubes and processed blade flanges into a vacuum furnace and place them in a vacuum furnace better than 1×10 -3 Under the conditions of Pa, the degassing temperature is 700-900℃, and the degassing time is 1h / mm wall thickness. High-temperature dehydrogenation is carried out. The dehydrogenation process includes a heating process, a heat preservation process and a cooling process. During the cooling process, the temperature zone of 900-600℃ must be quickly avoided to avoid the formation of carbide precipitation.

3. The method according to claim 1, characterized in that: The activated carbon rods selected from activated carbon raw materials and processed to form adsorption assemblies specifically include the following steps: Selecting a raw material suitable for making activated carbon, wherein the raw material is wood, coal or coconut shell, and crushing and screening the raw material to obtain activated carbon particles suitable for making activated carbon; The activated carbon particles are mixed evenly with a binder, an activator and an activator co-activator, and then extruded on a twin-screw extruder to obtain a molding material with a specific diameter; After the molding material is dried, dehydrated and activated, columnar activated carbon is initially obtained; The columnar activated carbon is subjected to the steps of primary water washing, acid washing, secondary water washing and drying to obtain the final activated carbon rod.

4. The method according to claim 1, characterized in that: The process of plating Ti and Ag on the activated carbon rod specifically comprises the following steps: Use high temperature resistant tape or specific tooling to cover the part of the activated carbon rod where no film is to be deposited; When the vacuum in the coating chamber of the multi-target DC planar magnetron sputtering coating machine is better than 1×10 -3 Pa, baking was performed at 180 °C for 2 h to activate the surface of the activated carbon and make it have better adhesion; 100-120 sccm of high-purity helium is introduced into the coating chamber of the multi-target DC planar magnetron sputtering coating machine to maintain the working pressure of the coating chamber at 0.19-0.23 Pa, the ion source voltage is set to 1500-2000 V, and the surface of the activated carbon rod is cleaned for 10-20 minutes; The vacuum angle of the vacuum unit was adjusted to 30-50° to ensure a working gas pressure of 0.23-0.3 Pa, and then the cylindrical Ti target current was set to 10-15 A to deposit the titanium film for 0.5-1 h; After the titanium film deposition is completed, the cylindrical Ti target is turned off, and the planar Ag target is turned on. The planar Ag target current is set to 5 to 7 A, and the titanium film is deposited for 2 to 3 hours.

5. The method according to claim 1, characterized in that: The method of welding the activated carbon rod to the metal plate by metal indium brazing specifically comprises the following steps: Introduce Metal 100 or In 97 The Ag3 film is laid flat on the processed metal plate, and the activated carbon rod with titanium film and silver film deposited is placed on the paved metal In 100 or In 97 On the Ag3 film, the metal In 100 or In 97 The Ag3 solder melts and the heating temperature is 160°C to 180°C, thereby completing the welding of the activated carbon rod and the metal plate.

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