Detection quality, preparation method and application of ultra-low magnetic susceptibility and remanent magnetic moment

Abstract

The present invention relates to a detection quality, preparation method and application thereof involving ultra-low magnetic susceptibility and remanent magnetic moment, and relates to the technical field of precious metal processing. The preparation method includes the following steps: Melting: Weigh raw materials, and perform melting by using a vacuum electron beam melting method to melt the raw materials, keep warm, pour, form an ingot, cool and solidify for casting; Preparing the detection quality: Anneal and cut the ingot after casting to obtain a number of ingot blocks, perform multi-directional forging on the ingot blocks, and perform surface treatment to obtain the detection quality. While improving production efficiency, this preparation method greatly reduces the content of ferromagnetic impurity elements in the inspection quality, has higher purity, significantly reduces the magnetic susceptibility and remanent magnetic moment of the Au-Pt alloy inspection quality, and meets the technical index requirements for gravitational wave detection.

Description

Technical Field

[0001] The present invention relates to the technical field of precious metal processing, and particularly to the detection quality, preparation method and application of ultra-low magnetic susceptibility and remanent magnetic moment. Background Art

[0002] Gravitational wave detection is one of the most difficult and cutting-edge technologies recognized in the world scientific community. Its basic principle is to detect the space-time distortion caused by gravitational waves by accurately measuring the picometer-level distance change between test masses inside a satellite through a laser interferometry ranging system. Therefore, it can be said that the test mass is a key component in the gravitational wave detection system. When a spacecraft is in operation, the test mass is in a constantly changing space magnetic field and the magnetic field generated by the spacecraft itself. The magnetic noise received by the test mass is one of the main sources of residual acceleration noise, and its magnitude depends on the magnetic field it is in, as well as the magnetic susceptibility and remanent magnetic moment of the test mass. Since the space magnetic field is uncontrollable and low-frequency signals cannot be completely shielded, the key to reducing magnetic noise is to develop test masses with ultra-low magnetic susceptibility and remanent magnetic moment. At the same time, the materials for test masses used in space gravitational wave detection also need to meet requirements such as high density and hardness, stable chemical properties, and good thermal and electrical conductivity. Currently, mixing diamagnetic Au and paramagnetic Pt in a certain proportion to form an Au-Pt alloy with near-zero magnetic susceptibility is the most promising technical solution for test mass preparation, but the values of its magnetic susceptibility and remanent magnetic moment are still difficult to meet the requirements in gravitational wave detection applications. Summary of the Invention

[0003] In view of the above problems, the present invention provides a preparation method for a test mass with ultra-low magnetic susceptibility and remanent magnetic moment. While improving production efficiency, this preparation method greatly reduces the content of ferromagnetic impurity elements in the test mass, has higher purity, significantly reduces the remanent magnetic moment of the Au-Pt alloy test mass, and meets the technical index requirements of gravitational wave detection.

[0004] To achieve the above object, the present invention provides a preparation method for a test mass with ultra-low magnetic susceptibility and remanent magnetic moment, including the following steps:

[0005] Smelting: Weigh the raw materials, and use the vacuum electron beam melting method for smelting to melt the raw materials, keep them warm, pour them, form an ingot, cool, solidify, and cast;

[0006] Preparing the test mass: Anneal the ingot after casting and cutting, obtain several ingot blocks, perform multi-directional forging on the ingot blocks, and perform surface treatment to obtain the test mass.

[0007] In the above preparation method, first use the high-vacuum electron beam melting method for smelting, purify gold and platinum using the saturated vapor pressures of various elements, and then use the conventional induction melting method to melt the alloy ingot with the purified raw materials, which can further reduce the content of impurity elements compared with direct smelting.

[0008] In one embodiment, there are also cleaning and drying steps before the step of weighing raw materials.

[0009] In one embodiment, the cleaning is ultrasonic cleaning, and the ultrasonic cleaning and drying include: soaking and cleaning with acetone 2 - 3 times to remove surface oil stains, pickling with hydrochloric acid solution 3 - 4 times to remove surface impurities, placing in an anhydrous ethanol and cleaning in a 3200H type ultrasonic cleaner for 10 - 15 min to wash away the residual hydrochloric acid solution on the surface of the raw materials, repeatedly rinsing with deionized water, and drying in an oven at 120 °C for 3 h

[0010] In one embodiment, in the ultrasonic cleaning and drying step, the hydrochloric acid solution contains 36.00 - 38.00% HCl.

[0011] In one embodiment, the raw materials include Au and Pt, and the mass of the raw materials ≥ 3 - 4 kg × the quantity of the detected mass.

[0012] In this preparation method, large - mass ingot casting is adopted, which can cast several inspection - quality ingots that meet the quality requirements at one time, significantly improving the production efficiency compared with other preparation methods.

[0013] In one embodiment, in the detected mass, the content of Au is 60 - 80% by mass percentage.

[0014] In one embodiment, in the step of weighing raw materials, the weighing amount of Au is 0.05% - 0.15% higher than the content of Au in the detected mass.

[0015] In one embodiment, the purity of the raw materials is 99.99%.

[0016] In one embodiment, the temperature of the melting is 150 - 250 °C higher than the melting point of the raw materials, and the melting time is 3 - 5 min; the heat preservation is realized by a graphite crucible.

[0017] In one embodiment, the heat preservation time is 3 - 5 min.

[0018] In one embodiment, the casting includes: pouring the melt after heat preservation into a water - cooled copper mold; the number of melt - casting is 3 - 5 times.

[0019] In one embodiment, the water - cooled copper mold is cylindrical, and the ratio of the diameter to the height is 2:1 - 4:1; during casting, the casting speed is controlled so that the molten liquid is uninterrupted and the ingot gradually solidifies. When performing re - melt - casting, after reversing the head and tail of the ingot, it is put into the melting furnace for re - melting.

[0020] In one embodiment, the slicing is achieved by a lathe, and the raw material of the cutting tool of the lathe is diamond.

[0021] In one embodiment, the annealing temperature is 900 - 1250 °C. During the annealing process, the ingot is placed in a high-temperature material container.

[0022] In one embodiment, the high-temperature material does not contain magnetic materials.

[0023] In one embodiment, the high-temperature material includes tungsten and graphite; a titanium alloy fixture without magnetic materials is used to clamp the ingot.

[0024] In one embodiment, the multi-directional forging is achieved by a pneumatic hammer. The hammer head of the pneumatic hammer is coated with a copper sheet. The multi-directional forging is carried out for 8 - 20 passes. The forging temperature of the multi-directional forging is 800 - 1200 °C, and the single-pass forging deformation amount of the multi-directional forging is ≤5%.

[0025] In one embodiment, before the multi-directional forging step, the hammer head and the workbench of the pneumatic hammer are also wiped with alcohol; the thickness of the copper sheet is 0.1 mm - 2 mm.

[0026] The above alcohol wiping can ensure a clean working environment and avoid introducing impurities; the above copper sheet can prevent the upper and lower hammer heads from directly contacting the ingot block.

[0027] In one embodiment, the size of the ingot block after multi-directional forging is a cube with a side length ≥50 mm.

[0028] In one embodiment, the surface treatment is achieved by a milling machine, and the raw material of the cutting tool of the milling machine is cemented carbide without magnetic materials.

[0029] The inventor found in the research that the most important factor affecting the magnetic susceptibility of the Au - Pt alloy is the content of the Pt element, and the main factor affecting the remanent magnetic moment of the Au - Pt alloy is the content of ferromagnetic impurity elements in the inspection mass. Therefore, in the whole process of processing the inspection mass of the Au - Pt alloy, in order to reduce the content of ferromagnetic impurity elements in the inspection mass, it is necessary to avoid the direct contact between the inspection mass of the Au - Pt alloy and equipment, molds, cutting tools, tools, etc. containing ferromagnetic elements such as Fe, Co, and Ni as much as possible, so as to minimize the content of ferromagnetic impurity elements in the inspection mass, and then reduce the magnetic susceptibility and remanent magnetic moment of the inspection mass to meet the technical index requirements of gravitational wave detection.

[0030] In one embodiment, the surface treatment includes: processing the ingot block after multi-directional forging to make the surface flat and smooth, without cracks, inclusions, and pores, and the surface roughness ≤0.2 μm.

[0031] In one embodiment, the size of a single detected mass after surface treatment is (50±1) mm×(50±1) mm×(50±1) mm.

[0032] The present invention also provides a detected mass obtained by the preparation method, and the magnetic susceptibility |χ| of the detected mass ≤ 8×10 -6 , and the remanent magnetic moment ≤ 25 nAm 2 .

[0033] The present invention also provides an application of the detected mass in a gravitational wave detection system.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The detected mass with ultra-low magnetic susceptibility and remanent magnetic moment, the preparation method and the application thereof of the present invention. The Au-Pt alloy inspection mass for gravitational wave detection obtained by this preparation method can effectively improve the production efficiency by melting large-mass ingots and machining multiple inspection masses at one time. Different from the previously studied alloy materials for gravitational wave detection, the alloy materials for gravitational wave detection mainly form rod-shaped raw materials through measures such as regulating alloy composition and dense and uniform heat treatment, rather than the detected mass that can be directly launched into space for application. In this case, by using a customized high-temperature material box to isolate the Au-Pt alloy block from the heat treatment furnace during heat treatment, using a Cu sheet to isolate the Au-Pt alloy block from the upper and lower hammer heads of the air hammer during forging, and using diamond and cemented carbide tool bits to machine the Au-Pt alloy inspection mass during turning and milling, etc., the contact between the Au-Pt alloy and tools and accessories containing ferromagnetic elements is avoided in all aspects, and the detected mass is prepared. And through verification experiments, it is confirmed that the detected mass prepared by the present invention has ultra-low magnetic susceptibility and remanent magnetic moment, the magnetic susceptibility < 6.5×10 -6 , and the remanent magnetic moment < 18 nAm 2 . While improving the production efficiency, this preparation method greatly reduces the content of ferromagnetic impurity elements in the inspection mass, has higher purity, significantly reduces the magnetic susceptibility and remanent magnetic moment of the Au-Pt alloy inspection mass, and meets the technical index requirements for gravitational wave detection. Description of the Drawings

[0036] Figure 1 Schematic diagram of a qualified Au-Pt alloy inspection mass obtained by the preparation method of Example 1. Detailed Embodiments

[0037] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention.

[0039] Definition:

[0040] Detection quality: In the present invention, the detection quality is the core sensor in the gravitational wave detection system, and its shape is a cube.

[0041] Source:

[0042] Unless otherwise specified, the reagents, materials, and equipment used in this embodiment are all commercially available sources; unless otherwise specified, the test methods are all conventional test methods in the art.

[0043] Example 1

[0044] A detection quality with ultra-low magnetic susceptibility and remanent magnetic moment and its preparation method.

[0045] The specific preparation method is as follows:

[0046] The Au and Pt raw materials with a purity of ≥99.99% are soaked and cleaned in acetone for 2 - 3 times to remove surface oil stains, and then pickled 3 times with a concentrated hydrochloric acid solution (containing 36.00 - 38.00% HCl) to remove surface impurities. Then, anhydrous ethanol is used and placed in a 3200H-type ultrasonic cleaner for 10 minutes to wash away the residual hydrochloric acid solution on the surface of the raw materials. After that, deionized water is used for repeated rinsing, and it is placed in an oven and dried at 120°C for 3 hours. After ultrasonic cleaning and drying, clean and dry Au and Pt raw materials are weighed according to the Au-26Pt alloy with an electronic balance (in the finally formed test mass, the mass percentage of Au is 60 - 80%, and the mass percentage of Pt is 20 - 40%). During the weighing of the raw materials, 0.05wt.% - 0.15wt.% more Au raw materials than the content of Au in the test mass are weighed (the total mass of Au raw materials is 8g), and the total mass of the raw materials is 10.86 kg. The alloy is melted using a vacuum electron beam melting furnace. After the Au and Pt raw materials are completely melted, they are kept warm for 5 minutes in a high-purity graphite crucible, and then the melt is poured into a cylindrical water-cooled copper mold. After the ingot cools and solidifies, it is remelted again, and refined repeatedly 3 times. When melting, the melting temperature is 200°C higher than the melting point, and the melting time for each time is 5 minutes. The ratio of the diameter to the height of the adopted cylindrical water-cooled copper mold is 5:1. During pouring, the pouring speed is controlled to make the molten liquid continuous, and the ingot gradually solidifies. When remelting, after turning the head and tail of the ingot around, it is put into the melting furnace for re-melting.

[0047] The repeatedly refined ingot is subjected to homogenization annealing at 1000°C using a box-type resistance furnace. During annealing, the Au-Pt test mass is placed in a customized high-temperature material cubic box (such as a tungsten box, a graphite box, etc.), and a customized titanium alloy fixture without ferromagnetic elements such as Fe, Co, and Ni is used to clamp the Au-Pt alloy test mass. The ingot is divided into 3 segments using a lathe, and the masses of the three segments of the ingot are 3.28 kg, 3.52 kg, and 3.61 kg respectively.

[0048] Each ingot was subjected to multi-directional forging with an air hammer for 12 passes at a forging temperature of 800 °C. The size of the Au-Pt alloy inspection mass after forging was a cube with a side length of (54 ± 1) mm. Before multi-directional forging of the ingot, the air hammer head and the workbench were wiped with alcohol to ensure a clean working environment and avoid introducing impurities. During forging, Cu sheets with a thickness of 1 mm were coated on the upper and lower hammer heads of the air hammer to prevent direct contact between the upper and lower hammer heads and the inspection mass ingot, and the deformation amount of each forging was controlled at 5%. The surface of each Au-Pt alloy inspection mass was machined flat and smooth with a milling machine, and the cutter head of the milling machine was made of cemented carbide without ferromagnetic elements such as Fe, Co, and Ni. The sizes of the three final formed Au-Pt alloy inspection masses were 50.5 mm × 51.0 mm × 50.6 mm, 50.6 mm × 50.4 mm × 50.3 mm, and 50.2 mm × 50.5 mm × 50.5 mm respectively. After machining the surface of the Au-Pt alloy inspection mass with a milling machine, the surface was required to have no defects such as cracks, inclusions, and pores, and the surface roughness was 0.2 μm.

[0049] Comparative Example 1

[0050] The Au and Pt raw materials with a purity ≥ 99.99% were soaked and cleaned with acetone 2 - 3 times to remove surface oil stains, and then pickled 3 times with a concentrated hydrochloric acid solution (containing 36.00 - 38.00% HCl) to remove surface impurities. Then, they were placed in a 3200H-type ultrasonic cleaner with absolute ethanol and cleaned for 10 min to wash away the residual hydrochloric acid solution on the raw material surface. After that, they were repeatedly rinsed with deionized water and dried in an oven at 120 °C for 3 h. After ultrasonic cleaning and drying, the clean and dry Au and Pt raw materials were weighed according to the Au-26Pt alloy with an electronic balance (in the finally formed inspection mass, the mass percentage of Au was 60 - 80%, and the mass percentage of Pt was 20 - 40%). During the weighing of the raw materials, 0.05 wt.% - 0.15 wt.% more Au raw materials than the Au content in the inspection mass were weighed (the total mass of the Au raw materials was 2.6 g), and the total mass of the raw materials was 3.54 kg. The alloy was melted with a vacuum electron beam melting furnace. After the Au and Pt raw materials were completely melted, they were kept warm for 5 minutes in a graphite crucible, and then the melt was poured into a cylindrical water-cooled copper mold. After the ingot cooled and solidified, it was remelted again, and refined repeatedly 3 times. During melting, the melting temperature was 200 °C higher than the melting point, and the melting time for each time was 5 min. The ratio of the diameter to the height of the cylindrical water-cooled copper mold used was 3:1. During pouring, the pouring speed was controlled to make the molten liquid continuous, and the ingot gradually solidified. When remelting, the ingot was turned around head and tail and then put back into the melting furnace for re-melting.

[0051] The repeatedly refined ingot was subjected to homogenization annealing at 1000 °C in a box-type resistance furnace.

[0052] The ingot was subjected to multi-directional forging in 12 passes using an air hammer at a forging temperature of 800 °C. The size of the gold-platinum alloy inspection mass after forging was a cube with a side length of (54 ± 1) mm. The surface of the gold-platinum alloy inspection mass was machined smooth using a milling machine. The final dimensions of the Au-Pt alloy inspection mass were 50.2 mm × 50.5 mm × 50.4 mm. After machining the surface of the gold-platinum alloy inspection mass with a milling machine, the surface was required to be free of defects such as cracks, inclusions, and pores, and the surface roughness was 0.2 μm.

[0053] Experimental Example

[0054] I. The inspection mass prepared by the above method was tested.

[0055] Testing methods: GB / T15072.1-2008, GB / T15072.3-2008, GB / T25934.2-2010, YS / T1493-2021, YS / T372.2-2006

[0056] The measurement methods for magnetic susceptibility and remanent magnetic moment were as follows: The volume magnetic susceptibility of the Au-Pt alloy was measured using a PPMS DynaCool type comprehensive physical property measurement system (PPMS). The comprehensive physical property measurement system is a fully automated large platform for comprehensive measurement of various physical properties (covering various measurement functions such as magnetism, electricity, and thermology). On the one hand, it provides an environment with a wide range of temperature research intervals, magnetic field research intervals, common electronic circuits, and common control interfaces for various measurements; on the other hand, it can also provide fully automated measurement methods for various physical properties based on this platform and the corresponding measurement devices. The surface of the Au-Pt alloy specimen was manually polished, cut into strip-shaped small samples with dimensions of 4 mm × 6 mm and a mass greater than 0.5 g, washed 2 - 3 times with hydrochloric acid, then ultrasonically cleaned with absolute ethanol for 10 min, and after drying, the magnetic susceptibility and remanent magnetic moment were tested.

[0057] II. After testing, the impurity components of the three Au-Pt alloy inspection masses (test masses 1, 2, and 3) prepared by the preparation method of Example 1 above were detected as shown in the following table. The magnetic susceptibility and remanent magnetic moment were respectively (5.8 ± 0.5) × 10 -6 and (17.4 ± 0.2) nAm 2 . The impurity components of the Au-Pt alloy inspection mass prepared by the comparative example were detected as shown in the following table. The magnetic susceptibility and remanent magnetic moment were respectively 10.3 × 10 -6 and 35.7 nAm 2 . The qualified Au-Pt alloy inspection mass obtained by the preparation method of Example 1 is as Figure 1 shown.

[0058] Table 1 Impurity Components of Each Test Mass

[0059]

[0060]

[0061] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as falling within the scope described in this specification.

[0062] The above-described embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A preparation method for detecting the quality of ultra-low magnetic susceptibility and remanent magnetic moment, characterized in that, Including the following steps: Smelting: Weigh the raw materials, and use the vacuum electron beam melting method for smelting to melt the raw materials, keep them warm, pour them, form an ingot, cool and solidify, and use induction melting for casting; Preparation detection quality: Anneal the ingot after melting and casting, cut it to obtain several ingot blocks, perform multi-directional forging on the ingot blocks, and perform surface treatment to obtain the detection quality; the detection quality is the detection quality of the Au-26Pt alloy, and the magnetic susceptibility of the detection quality ≤8×10 -6 , and the remanent magnetic moment ≤25 nAm 2 ; during the annealing process, the ingot is placed in a high-temperature material container, and the high-temperature material does not contain magnetic materials; the cutting is realized by a lathe, and the raw material of the tool bit of the lathe is diamond; the multi-directional forging is realized by a pneumatic hammer, and the hammer head of the pneumatic hammer is coated with copper sheets; the surface treatment is realized by a milling machine, and the raw material of the tool bit of the milling machine is hard alloy that does not contain magnetic materials.

2. The preparation method according to claim 1, characterized in that, The mass of the raw materials ≥ 3 - 4 kg × the quantity of the detected mass.

3. The preparation method according to claim 1, characterized in that, The temperature of the smelting is 150 - 250°C higher than the melting point of the raw materials, and the time of the smelting is 3 - 5 min; the heat preservation is realized by a graphite crucible.

4. The preparation method according to claim 1, wherein, The temperature of the annealing is 900 - 1250°C.

5. The preparation method according to claim 1, characterized in that, The multi-directional forging is 8 - 20 passes, the forging temperature of the multi-directional forging is 800 - 1200°C, and the single-pass forging deformation amount of the multi-directional forging ≤ 5%.

6. The detected mass obtained by the preparation method according to any one of claims 1 - 5.

7. The application of the detected mass according to claim 6 in a gravitational wave detection system.

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