A process for reducing the outgassing rate of ferrite surfaces

Abstract

This invention relates to the field of ultra-high vacuum acquisition technology, and more particularly to a process for reducing the surface gas exudation rate of ferrite. The process of this invention includes step S1 pretreatment, step S2 high-temperature degassing, and step S3 post-treatment; wherein, step S2 high-temperature degassing includes: placing the ferrite in a degassing furnace; evacuating the degassing furnace; starting the heating system of the degassing furnace, heating the ferrite to 500-600℃ at a heating rate of 1-2℃ / min and holding it at that temperature for 0.5-1h, then heating it to 850-900℃ at a heating rate of 1-2℃ / min and holding it at that temperature for 1-2h, then cooling it to 300-500℃ at a cooling rate of 1-2℃ / min, and finally turning off the heating system to allow the ferrite to cool with the furnace. The process of this invention can effectively reduce the surface gas exudation rate of ferrite, enabling the ferrite to be used in 10 ‑ 10 The Pa ultra-high vacuum system can also prevent ferrite from cracking and being damaged during the degassing process.

Description

Technical Field

[0001] This invention relates to the field of ultra-high vacuum technology, and more particularly to a process for reducing the gas outflow rate of ferrite surfaces. Background Technology

[0002] In particle accelerators, kicker magnets are special dipole magnets that operate in a fast-pulse mode, primarily used in the injection and extraction systems of ring accelerator beams. In the High Intensity Heavy Ion Accelerator (HIAF), the fast-pulse magnets generate extremely high inductance voltages. To prevent high-voltage arcing and breakdown, the kicker magnets are installed in an extremely high vacuum environment, with the beam passing directly through their center. To reduce eddy current losses, the core is made of ferrite material with extremely high resistivity. Considering the extremely high vacuum environment, the gas efflux rate on the ferrite surface determines the final vacuum level. During the processing of ferrite, a certain amount of gas dissolves and adsorbs. If the surface treatment process is inadequate, a large amount of gas will gradually be released into the system under vacuum conditions, failing to achieve a vacuum level of 10. -10 The process involves an extremely high vacuum state (Pa). Traditional techniques typically employ high-temperature degassing to reduce the surface gas exudation rate of materials. However, the degassing temperature, degassing rate, and insulation methods are primarily designed for stainless steel materials, which are incompatible with the properties of ferrite materials. This fails to meet the requirements for reducing the surface gas exudation rate, and the degassing process can also lead to cracking and damage to the ferrite. Therefore, it is essential to propose a process for reducing the surface gas exudation rate of ferrite to address these issues. Summary of the Invention

[0003] This invention provides a process for reducing the surface gas extrusion rate of ferrite, which solves the problems of existing technologies that use high-temperature degassing to reduce the surface gas extrusion rate of materials, which cannot meet the requirements for reducing the surface gas extrusion rate of ferrite, and the ferrite may crack and be damaged during the degassing process.

[0004] According to a first aspect of the present invention, the present invention provides a process for reducing the gas outgassing rate of ferrite surface, comprising step S1 pretreatment, step S2 high-temperature degassing and step S3 posttreatment.

[0005] Specifically, step S2, high-temperature degassing, includes the following steps:

[0006] S2.1: Place the ferrite in the degassing furnace;

[0007] S2.2: Evacuate the degassing furnace;

[0008] S2.3: Start the heating system of the degassing furnace, heat the ferrite to 500-600℃ at a heating rate of 1-2℃ / min and hold for 0.5-1h, then heat to 850-900℃ at a heating rate of 1-2℃ / min and hold for 1-2h, then cool to 300-500℃ at a cooling rate of 1-2℃ / min, and turn off the heating system to allow the ferrite to cool with the furnace.

[0009] This invention's experiments revealed that degassing parameters such as temperature, heating rate, cooling rate, and holding time during high-temperature degassing significantly affect the final ferrite surface gas exudation rate and cracking. Considering that excessively rapid heating and cooling rates can lead to cracking due to uneven heat distribution, this invention controls the heating and cooling rates to within 1-2℃ / min. When the baking temperature reaches 500-600℃, hold for 0.5-1 hour, depending on the ferrite volume, to ensure sufficient heat conduction, then continue heating. When the temperature reaches 850-900℃, hold for 1-2 hours, then begin the cooling phase at a rate of 1-2℃ / min. When the temperature drops to 300-500℃, shut off the heating system, and allow the ferrite to cool with the degassing furnace. Through this strict control of degassing parameters during high-temperature degassing, the ferrite surface gas exudation rate can be reduced more effectively, enabling the ferrite to be used in applications such as 10... -10 Even in an extremely high vacuum environment of Pa, ferrite will not crack or be damaged.

[0010] This invention provides a process for reducing the surface gas extrusion rate of ferrites, which significantly improves the performance of ferrites with different surface areas and shapes. For ferrites with large surface areas and bent shapes, reducing their surface gas extrusion rate while preventing surface cracking is quite difficult. Experiments of this invention have shown that the process for reducing the surface gas extrusion rate of ferrites also exhibits good improvement effects on ferrites with large surface areas and bent shapes. For example, the outer surface area of ​​the ferrite is 500-1000 cm². 2 The external shape is U-shaped, triangular, square, etc. In some specific embodiments, the external surface area of ​​the ferrite is 800-900 cm². 2 Its external shape is "U".

[0011] Furthermore, in step S2.1, the ferrites are placed at intervals in the degassing furnace to facilitate the removal of gas adsorbed on the ferrite surface. Preferably, the interval distance is ≥20mm.

[0012] Further, in step S2.2, the degassing furnace is evacuated to a vacuum degree ≤10. -3 Pa is beneficial for removing gas from materials and improving the surface quality of materials.

[0013] Furthermore, the vacuum degassing furnace's vacuum generation equipment is determined based on the furnace cavity size, with the main principle being to avoid the oil vapor generated by the lubricating oil affecting the ferrite degassing effect. Therefore, when the degassing furnace cavity is small, an oil-free lubricated scroll dry pump combined with a turbomolecular pump unit can be used; when the degassing furnace cavity is large, a pumping system consisting of a slide valve pump, a Roots pump, an oil diffusion pump, and a liquid nitrogen cold trap can be used.

[0014] Furthermore, the preprocessing step S1 specifically includes the following steps:

[0015] S1.1: Nitrogen purging or vacuum cleaner removal; specifically, high-pressure nitrogen is used to purge the ferrite surface to remove visible impurities. For larger ferrite surfaces, a vacuum cleaner can also be used to remove impurities.

[0016] S1.2: Wipe the ferrite surface with a non-woven cloth soaked in alcohol for initial cleaning;

[0017] S1.3: Ultrasonic cleaning;

[0018] S1.4: Rinse repeatedly with running deionized water until no foam remains;

[0019] S1.5: Drying.

[0020] This invention treats ferrites with nitrogen purging or vacuum cleaning, primary cleaning, ultrasonic cleaning, repeated rinsing with flowing deionized water, and drying. This process ensures a clean ferrite surface, facilitating subsequent high-temperature degassing and improving the effectiveness and quality of these treatments. Nitrogen purging and vacuum cleaning effectively remove particulate impurities such as dust and debris from the ferrite surface. Primary cleaning removes chemical residues such as oil and residual chemical reagents. Ultrasonic cleaning penetrates even the smallest crevices on the ferrite surface, thoroughly removing extremely fine dust and dirt, resulting in a high degree of cleanliness. Repeated rinsing with flowing deionized water completely removes any contaminants and residual cleaning solution generated during the cleaning process, further enhancing the cleanliness of the ferrite surface.

[0021] Furthermore, in step S1.1, the nitrogen purity during the nitrogen purging process is ≥99.99%.

[0022] Furthermore, in step S1.3, the cleaning solution used during ultrasonic cleaning includes one or more of a weakly acidic water-based solution, a weakly alkaline water-based solution, or isopropanol.

[0023] A weakly acidic water-based solution generally refers to a cleaning solution with a pH value between 4 and 6, and can be prepared using hydrochloric acid, sulfuric acid, citric acid, etc. A weakly alkaline water-based solution generally refers to a cleaning solution with a pH value between 8 and 10, and can be prepared using sodium hydroxide, sodium carbonate, etc.

[0024] In some specific embodiments, in step S1.3, the cleaning solution used during ultrasonic cleaning is a weakly acidic water-based solution and a weakly alkaline water-based solution. During ultrasonic cleaning, a weakly acidic water-based solution is first used to remove oil stains at a temperature of 50-65°C for 15-30 minutes. Then, a weakly alkaline water-based solution is used to neutralize the weakly acidic solution at a temperature of 50-65°C for 15-30 minutes.

[0025] In some specific embodiments, isopropanol is used as the cleaning solution in step S1.3 during ultrasonic cleaning. Specifically, the ferrite is placed in an ultrasonic cleaning tank, and clean ceramic blocks are placed at intervals at the contact points between the bottom of the ferrite and the ultrasonic cleaning tank to ensure sufficient cleaning solution at the bottom of the ferrite to improve the cleaning effect. 3-5 blocks are placed each time, and ultrasonic cleaning is performed for 15-30 minutes.

[0026] Furthermore, in step S1.3, during ultrasonic cleaning, a gap is left between the ferrite and the contact area of ​​the ultrasonic cleaning tank to allow the cleaning solution to fully wet the ferrite and improve the cleaning effect.

[0027] Furthermore, in step S1.5, the drying temperature is 100℃~150℃. A vacuum drying oven or a forced-air drying oven can be used for drying.

[0028] Furthermore, the post-processing step S3 specifically includes visual inspection after degassing, and preservation by wrapping the ferrite in aluminum foil and placing it in a vacuum or nitrogen environment. Using this preservation method, the treated ferrite will not be contaminated by impurities such as oxygen, water vapor, and dust in the environment. If it is not preserved in the above manner after degassing, the ferrite surface may re-adsorb oxygen, water vapor, and other gases, affecting its surface quality.

[0029] Furthermore, throughout the entire operation, the operators wore cleanroom suits and latex gloves.

[0030] The beneficial effects of the technical solution provided by this invention are as follows: Compared with the prior art, a process for reducing the surface gas extrusion rate of ferrite can effectively reduce the surface gas extrusion rate of ferrite, enabling ferrite to be used in 10 -10 The ultra-high vacuum system at Pa effectively prevents ferrite from cracking and being damaged during degassing. This process offers advantages such as simple operation, low equipment requirements, and significant degassing effect. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 This is a process flow diagram of reducing the gas outburst rate on the ferrite surface provided in Embodiment 1 of the present invention.

[0033] Figure 2 This is a process curve diagram of high-temperature degassing in a process for reducing the gas outgassing rate of ferrite surface provided in Embodiment 1 of the present invention.

[0034] Figure 3 This is a comparison chart of the gas exhalation rate curves of ferrite surface in Embodiment 1 of the present invention and Comparative Examples 1, 3, and 4.

[0035] Figure 4 This is a diagram of the ferrite cracking state in Comparative Example 2 of the present invention.

[0036] Figure 5 This is a diagram showing the cracked state of the ferrite portion in Comparative Example 3 of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0038] Example 1

[0039] The example uses CMD5005 Ni-Zn ferrite manufactured by International Magnetic Materials Co., Ltd., with an external surface area of ​​816 cm². 2 Its density is 5.27 g / cm³. 3 The external shape is "U", and 22 pieces are processed in the same batch.

[0040] Specifically, this embodiment provides a process for reducing the outgassing rate of ferrite surfaces, such as... Figure 1 As shown, it includes the following steps:

[0041] Step S1: Pretreatment of ferrite. Pretreatment involves cleaning the batch of ferrite using nitrogen purging combined with ultrasonic cleaning. During transport, operators wear cleanroom suits and latex gloves.

[0042] Specifically, S1.1: High-pressure nitrogen with a purity of 99.99% is used to purge the ferrite to remove visible impurities and packaging residues.

[0043] S1.2: Use a non-woven cloth soaked in alcohol to perform a primary cleaning of the ferrite. Replace the non-woven cloth immediately if it becomes stained.

[0044] S1.3: In this embodiment, isopropanol is used as the ultrasonic cleaning fluid. The ferrite is placed in the ultrasonic cleaning tank, and clean ceramic blocks are placed at intervals at the contact points between the bottom of the ferrite and the ultrasonic cleaning tank to ensure sufficient cleaning fluid at the bottom of the ferrite, thereby improving the cleaning effect. Four blocks are placed each time, and ultrasonic cleaning is performed for 15 minutes.

[0045] S1.4: Rinse the ferrite repeatedly with deionized water.

[0046] S1.5: Dryed at 100°C in a vacuum drying oven.

[0047] Step S2: Use a vacuum degassing furnace to bake and degas 22 ferrite pieces at high temperature.

[0048] S2.1: Place the ferrite in the vacuum degassing furnace, leaving a certain space (about 20~30mm) between adjacent ferrites and between the ferrite and the shelf to facilitate better discharge of the gas adsorbed by the material.

[0049] S2.2: Evacuate the air from the furnace until the pressure is ≤10. -3 Pa.

[0050] S2.3: Start the heating system, set both the heating and cooling rates to 2℃ / min, heat to 600℃ and hold for 1 hour, then heat to 900℃ and hold for 2 hours, then begin the cooling phase. Cool to 400℃ and shut off the heating system to allow the ferrite to cool with the furnace. The specific baking process curve is as follows: Figure 2 As shown.

[0051] Step S3: After the ferrite temperature drops to room temperature, remove the ferrite, check for quality issues, wrap it in aluminum foil, and seal it using a vacuum packaging machine. Throughout the entire operation, operators wear cleanroom suits and latex gloves.

[0052] Comparative Example 1

[0053] This comparative example provides a process for reducing the gas outgassing rate on the ferrite surface. Compared with Example 1, Comparative Example 1 did not perform the high-temperature vacuum degassing process in step S2, but the other steps were the same as in Example 1.

[0054] Comparative Example 2

[0055] This comparative example provides a process for reducing the gas outgassing rate of ferrite surface. Compared with Example 1, in the S2.2 stage of Comparative Example 2, the heating rate and cooling rate are both 5℃ / min, and the remaining process steps are the same as in Example 1.

[0056] Comparative Example 3

[0057] This comparative example provides a process for reducing the gas outgassing rate of ferrite surface. Compared with Example 1, in step S2.2, the temperature is directly raised to 900°C and held for 2 hours, and then the cooling stage is entered. The remaining process steps are the same as in Example 1.

[0058] Comparative Example 4

[0059] This comparative example provides a process for reducing the gas outgassing rate of ferrite surface. Compared with Example 1, in step S2.2, the temperature is raised to 300°C and held for 1 hour, then raised to 600°C and held for 2 hours, and then the cooling stage is entered. The remaining process steps are the same as in Example 1.

[0060] In summary, the ferrite gas exit rates of Example 1 of the present invention are compared with those of Comparative Examples 1, 3, and 4 as follows: Figure 3 As shown in the figure, the process method used in this invention significantly reduces the gas efflux rate on the ferrite surface. Four ferrite samples from Example 1 and Comparative Example 1 were selected for ultimate vacuum testing. The main pump of the testing apparatus used a sputtering ion pump and a titanium sublimation pump. After baking at 250°C, as shown in Table 1, the ultimate vacuum of Example 1 was 9.6 × 10⁻⁶. -10 Pa, the limiting vacuum of Comparative Example 1 is 1.5 × 10 Pa. -8 Pa, it can be seen that the ferrite processed according to the process of the present invention can be used at 10 -10 Extremely high vacuum systems. Furthermore, such as... Figure 4 As shown, the ferrite treated in Comparative Example 2 exhibits obvious cracking, such as... Figure 5 As shown, the ferrite surface treated in Comparative Example 3 showed a small amount of cracking. In Example 1, all ferrites were tested and found to be free of cracking or damage. Therefore, the process method used in this invention is highly safe, does not cause cracking, and has a significant effect on reducing surface gas extrusion rate.

[0061] Table 1

[0062]

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for reducing the outgassing rate of ferrite surfaces, characterized in that, It includes step S1 pretreatment, step S2 high-temperature degassing and step S3 posttreatment; Specifically, step S2, high-temperature degassing, includes the following steps: S2.1: Place the ferrite in the degassing furnace; S2.2: Evacuate the degassing furnace; S2.3: Start the heating system of the degassing furnace, heat the ferrite to 500-600℃ at a heating rate of 1-2℃ / min and hold for 0.5-1h, then heat to 850-900℃ at a heating rate of 1-2℃ / min and hold for 1-2h, then cool to 300-500℃ at a cooling rate of 1-2℃ / min, and turn off the heating system to allow the ferrite to cool with the furnace; Step S1 preprocessing specifically includes the following steps: S1.1: Nitrogen purging or vacuum cleaner removal; S1.2: Wipe the ferrite surface with a non-woven cloth soaked in alcohol for initial cleaning; S1.3: Ultrasonic cleaning; S1.4: Rinse repeatedly with running deionized water until no foam remains; S1.5: Drying; Step S3 post-processing specifically includes degassing followed by visual inspection, and then wrapping the product in aluminum foil and storing it in a vacuum or nitrogen environment.

2. The process for reducing the surface gas exudation rate of ferrite according to claim 1, characterized in that, In step S2.1, ferrites are placed intermittently in the degassing furnace.

3. The process for reducing the surface gas exudation rate of ferrite according to claim 2, characterized in that, In step S2.1, the interval distance is ≥20mm.

4. The process for reducing the surface gas exudation rate of ferrite according to claim 1, characterized in that, In step S2.2, the degassing furnace is evacuated to a vacuum level ≤10. -3 Pa.

5. The process for reducing the surface gas exudation rate of ferrite according to claim 1, characterized in that, In step S1.1, the nitrogen purity during the nitrogen purging process is ≥99.99%.

6. The process for reducing the surface gas exudation rate of ferrite according to claim 1, characterized in that, In step S1.3, the cleaning solution used in ultrasonic cleaning includes one or more of the following: a weakly acidic water-based solution, a weakly alkaline water-based solution, or isopropanol.

7. The process for reducing the surface gas exudation rate of ferrite according to claim 1, characterized in that, In step S1.3, during ultrasonic cleaning, a gap is left between the ferrite and the contact area of ​​the ultrasonic cleaning tank.

8. The process for reducing the surface gas exudation rate of ferrite according to claim 1, characterized in that, In step S1.5, the drying temperature is 100℃~150℃.

9. A process for reducing the surface gas exudation rate of ferrite according to any one of claims 1-8, characterized in that, Throughout the entire operation, the operators wore cleanroom suits and latex gloves.

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