Preparation method of high-reliability high-temperature excitation coil

Abstract

The application discloses a preparation method of a high-reliability high-temperature excitation coil and relates to the technical field of magnetic suspension. The preparation method of the high-reliability high-temperature excitation coil comprises the following steps: first, winding a metal wire into a required multilayer coil; then, performing ion bombardment cleaning on the metal wire, sputtering a mobile metal on the surface of the metal wire, and sputtering an interface metal; opening holes on the surface of a silicon nitride ceramic to obtain a silicon nitride ceramic insulating layer with the holes, and performing vacuum sintering on the insulating layer and the metal wire to obtain the high-reliability high-temperature excitation coil with a multilayer structure. In the application, the brazing of the metal wire and the silicon nitride ceramic is based on the AMB brazing process principle, the mobile metal layer sputtered on the surface of the metal wire wets the surface of the silicon nitride ceramic and reacts with the surface at high temperature, so that the metal wire and the silicon nitride ceramic are combined closely and have better reliability, and the prepared high-temperature excitation coil has a longer service life.

Description

Technical Field

[0001] This invention relates to the field of magnetic levitation technology, specifically a method for preparing a highly reliable high-temperature excitation coil. Background Technology

[0002] With the rapid development of the low-altitude economy and the increasing demands for faster, higher, farther, more economical, more reliable, and more environmentally friendly aircraft, magnetic levitation bearings, compared to traditional mechanical bearings, have zero mechanical friction between the stator and rotor, zero operating resistance, no heat generation, and no need for cooling and lubrication systems. This reduces size and weight, and the levitation operation reduces mechanical noise and vibration, improving the overall stability of the fan. They also offer higher reliability and longer service life, making them highly promising for development and application in high-tech fields such as aerospace. Currently, the excitation coils of high-temperature magnetic levitation bearings mostly use high-temperature resistant insulating materials to wrap the wires. Common high-temperature resistant insulating materials include ceramics and glass fiber. During the coil winding process, due to the large bending radius and high operating temperature (typically around 500–650℃), the long-term high-temperature environment easily damages the insulation layer of the coil wires, significantly affecting the coil's service life. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing a high-reliability high-temperature excitation coil, so as to solve the problems mentioned in the prior art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a high-reliability high-temperature excitation coil, comprising a silicon nitride ceramic insulating layer and a metal conductor layer; the metal conductor layer comprises a metal conductor and a metal layer disposed on the surface of the metal conductor;

[0005] The metal layer includes an active metal layer and an interface metal layer. The active metal layer is one or more of Ti (titanium) and Zr (zirconium), and the interface metal layer is one or more of Cu (copper), Ni (nickel), and Ag (silver).

[0006] Furthermore, the winding direction of the metal wire is clockwise from the outside to the inside or clockwise from the inside to the outside; the metal wire layer is a multi-layered structure with the coil routing directions of adjacent metal wire layers being opposite.

[0007] Furthermore, the silicon nitride ceramic insulating layer is located between two adjacent metal conductor layers, and the silicon nitride ceramic insulating layer is provided with through holes; the tail end of the metal conductor passes through the through hole and is connected in series with the head end of the adjacent metal conductor through a connecting wire.

[0008] A method for preparing a high-reliability high-temperature excitation coil includes the following steps:

[0009] Step 1: Wind the metal wire into a spiral to form a metal coil;

[0010] Step 2: Perform ion bombardment cleaning on the metal coil obtained in Step 1; then sputter an active metal to form an active metal layer; sputter an interface metal to form an interface metal layer, thus obtaining a metal wire layer;

[0011] Step 3: Create through holes on the surface of the silicon nitride ceramic to obtain a silicon nitride ceramic insulating layer;

[0012] Step 4: Alternately stack the silicon nitride ceramic insulation layer and the metal wire layer obtained in Step 3 to assemble and obtain a coil semi-finished product;

[0013] Step 5: The coil semi-finished product obtained in Step 4 is sintered at high temperature to obtain a high-temperature excitation coil.

[0014] Furthermore, the metal wire thickness in step 1 is 0.1-0.5mm, the metal coil width is 1-3mm, and the spacing between the wires is 0.3-0.5mm.

[0015] Furthermore, the reactive metal layer mentioned in step 2 is one or more of Ti and Zr;

[0016] The interface metal layer mentioned in step 2 is one or more of Cu, Ni, and Ag.

[0017] Furthermore, the process conditions for ion bombardment cleaning in step 2 are: vacuum degree 8-1000Pa, argon pressure 1.6-2.6Pa, voltage 0.6-0.8KV, and cleaning time 120-300s;

[0018] The sputtering process conditions for the reactive metal in step 2 are: furnace cavity vacuum degree 10 -4 -10 -3 Pa, argon pressure 0.25-1 Pa, sputtering power 7-15 KW, voltage 750-850 V, time 10-20 min, temperature 250-350 ℃;

[0019] The sputtering process conditions for the interface metal are: furnace cavity vacuum degree 10 -4 -10 -3 Pa, argon pressure 0.8-1.5 Pa, sputtering power 16-26 KW, voltage 650-750 V, time 80-100 min, temperature 280-380 ℃;

[0020] In step 2, the thickness of the reactive metal layer is 800-900 nm; the thickness of the interface metal layer is 1-3 μm.

[0021] Furthermore, the through hole mentioned in step 3 is an inner ring through hole or an outer ring through hole. The inner ring through hole is used to pass through the tail end of the metal wire wound clockwise from the outside to the inside, and the outer ring through hole is used to pass through the tail end of the metal wire wound clockwise from the inside to the outside.

[0022] Furthermore, in step 4, the assembly method is as follows: the tail end of the metal wire wound clockwise from the outside to the inside passes through the inner ring through hole on the silicon nitride ceramic insulation layer and is connected in series with the head end of the adjacent metal wire through the connecting wire; the tail end of the metal wire wound clockwise from the inside to the outside passes through the outer ring through hole on the silicon nitride ceramic insulation layer and is connected in series with the head end of the adjacent metal wire through the connecting wire, thus connecting the coils of each layer of metal wires and the silicon nitride ceramic insulation layer into one unit.

[0023] Furthermore, the number of metal conductor layers in step 4 is 15-30 layers;

[0024] The height of the connecting wire is 0.35-0.55mm.

[0025] Furthermore, the height of the connecting wire in step 1 is 0.1-0.5 mm greater than the thickness of the silicon nitride ceramic insulation layer in step 3.

[0026] Furthermore, the process conditions for high-temperature sintering in step 5 are: temperature 880-1880℃, pressure 0.1-0.3MPa, and time 30-50min.

[0027] Furthermore, the metal wire is either silver or nickel wire; the silver wire has a purity of 99.99% and originates from Jiangsu Kangtian Alloy Materials Co., Ltd.

[0028] Nickel wire: 99.9% purity, sourced from Changfeng (Wuxi) Metal Products Co., Ltd.

[0029] Titanium powder: 80 mesh, 99.7% purity, sourced from Beijing Xingrongyuan Technology Co., Ltd.

[0030] Zirconium powder: 20-80 mesh, 99.5% purity, sourced from Tianjin Gaoke New Materials Technology Co., Ltd.

[0031] Copper powder: 80-300 mesh, 99% purity, sourced from Hubei Darli Chemical Co., Ltd.

[0032] Nickel powder: 20-80 mesh, 99.5% purity, sourced from Tianjin Gaoke New Materials Technology Co., Ltd.

[0033] Silver powder: 20-80 mesh, 99.5% purity, sourced from Tianjin Gaoke New Materials Technology Co., Ltd.

[0034] Silicon nitride ceramic: thickness 0.2-0.4mm, surface roughness Ra0.2-0.6μm, sourced from Dongguan Gravel Industry Investment Co., Ltd.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] 1. Traditional excitation coils use high-temperature resistant ceramics or glass fibers to wrap metal wires as insulation. Due to the brittleness of the ceramics or glass fibers themselves and the large bending radius of the wound coil, they are prone to damage under long-term high operating temperatures (550-650℃), affecting the service life of the excitation coil. In this invention, the excitation coil adopts a layered structure, namely metal wire circuit + silicon nitride ceramic + metal wire circuit + silicon nitride ceramic + ... + metal wire circuit. The insulation layer uses sheet-like silicon nitride ceramic sheets. The metal wires do not need to be wrapped with ceramics or glass fibers, and there is no heat dissipation barrier layer on the surface of the metal wires, which increases the heat dissipation effect of the metal wires.

[0037] 2. The brazing of metal wires and silicon nitride ceramics is based on the AMB (Active Metal Brazing) process. The active metal layer sputtered on the surface of the metal wire wets the surface of the silicon nitride ceramic and reacts with it at high temperature, so that the metal wire and silicon nitride ceramic are tightly bonded. The bonding layer is achieved through a chemical reaction at high temperature. The bonding strength between the ceramic and the metal coil is high, which has higher reliability and service life.

[0038] 3. The interface metal layer protects the active metal layer from oxidation and loss of activity, which would lead to poor bonding between the metal wire and the silicon nitride ceramic. On the other hand, copper will undergo a eutectic reaction with the metal wire, thereby reducing the sintering temperature. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the preparation process of the present invention;

[0040] Figure 2 This is a schematic diagram of the metal wire wound clockwise from the outside to the inside according to the present invention;

[0041] Figure 3 This is a schematic diagram of the metal wire wound clockwise from the inside out according to the present invention;

[0042] Figure 4 This is a schematic diagram of the metal coil winding of the present invention;

[0043] Figure 5 This is a schematic diagram of the cross-section of the metal coil of the present invention;

[0044] Figure 6 This is a schematic diagram of the laser-cut inner ring through hole of the silicon nitride ceramic insulating layer of the present invention;

[0045] Figure 7 This is a schematic diagram of the laser-cut outer ring through-hole of the silicon nitride ceramic insulating layer of the present invention;

[0046] Figure 8This is a schematic diagram of the assembly of the metal wire wound clockwise from the outside to the inside and the silicon nitride ceramic insulating layer according to the present invention;

[0047] Figure 9 This is a schematic diagram of the assembly of the metal wire wound clockwise from the inside out and the silicon nitride ceramic insulating layer according to the present invention;

[0048] Figure 10 This is a schematic diagram of the product structure of the present invention.

[0049] In the diagram, 1-connecting wire, 2-inner through hole, 3-outer through hole, 4-metal wire wound clockwise from the outside to the inside, 5-silicon nitride insulating ceramic layer, 6-metal wire wound clockwise from the inside to the outside, and 7-metal coil. Detailed Implementation

[0050] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] In the following specific implementation,

[0052] The metal wire is silver wire with a purity of 99.99%, sourced from Jiangsu Kangtian Alloy Materials Co., Ltd.

[0053] The reactive metal layer is titanium, and the titanium powder is 80 mesh with a purity of 99.7%, sourced from Beijing Xingrongyuan Technology Co., Ltd.

[0054] The interface metal layer is copper, and the copper powder is 80-300 mesh with a purity of 99%, sourced from Hubei Darli Chemical Co., Ltd.

[0055] Silicon nitride ceramic: thickness 0.2-0.4mm, surface roughness Ra0.2-0.6μm, sourced from Dongguan Gravel Industry Investment Co., Ltd.

[0056] Example 1: A method for preparing a high-reliability high-temperature excitation coil, comprising the following steps:

[0057] Step 1: Spiral wind the metal wire to form a metal coil; the metal wire thickness is 0.1mm, the metal coil width is 1mm, and the spacing between the wires is 0.3mm;

[0058] Step 2: The metal coil obtained in Step 1 is subjected to ion bombardment cleaning; then, an active metal is sputtered to form an active metal layer; an interface metal is sputtered to form an interface metal layer, resulting in a metal wire layer; the ion bombardment cleaning process conditions are: vacuum degree 8 Pa, argon pressure 1.6 Pa, voltage 0.6 KV, cleaning time 120 s; the sputtering process conditions for the active metal are: furnace cavity vacuum degree 10 -4 The sputtering conditions for the interface metal were: argon pressure 0.25 Pa, sputtering power 7 kW, voltage 750 V, time 10 min, temperature 250 °C; furnace vacuum degree 10 Pa. -4 Pa, argon pressure 0.8 Pa, sputtering power 16 KW, voltage 650 V, time 80 min, temperature 280 ℃; active metal layer thickness 800 nm; interface metal layer thickness 1 μm;

[0059] Step 3: Create through holes on the surface of the silicon nitride ceramic to obtain a silicon nitride ceramic insulating layer; silicon nitride ceramic: thickness 0.2 mm, surface roughness Ra 0.2 μm;

[0060] Step 4: Alternately stack the silicon nitride ceramic insulation layer and the metal wire layer obtained in Step 3 to assemble the coil semi-finished product. The assembly method is as follows: the tail end of the metal wire wound clockwise from the outside to the inside passes through the inner ring through hole on the silicon nitride ceramic insulation layer and is connected in series with the head end of the adjacent metal wire through the connecting wire. The tail end of the metal wire wound clockwise from the inside to the outside passes through the outer ring through hole on the silicon nitride ceramic insulation layer and is connected in series with the head end of the adjacent metal wire through the connecting wire. The coils of each metal wire layer and the silicon nitride ceramic insulation layer are connected in series to form a whole. The number of metal wire layers is 15. The height of the connecting wire is 0.35mm.

[0061] Step 5: The coil semi-finished product obtained in Step 4 is subjected to high-temperature sintering to obtain the excitation coil; the high-temperature sintering process conditions are: temperature 880℃, pressure 0.1MPa, time 30min.

[0062] Example 2: A method for preparing a high-reliability high-temperature excitation coil, comprising the following steps:

[0063] Step 1: Spiral wind the metal wire to form a metal coil; the metal wire thickness is 0.3mm, the metal coil width is 2mm, and the spacing between the wires is 0.4mm;

[0064] Step 2: The metal coil obtained in Step 1 is subjected to ion bombardment cleaning; then, an active metal is sputtered to form an active metal layer; an interface metal is sputtered to form an interface metal layer, resulting in a metal wire layer; the process conditions for ion bombardment cleaning are: vacuum degree 500 Pa, argon pressure 2.0 Pa, voltage 0.7 KV, and cleaning time 200 s; the sputtering process conditions for the active metal are: furnace cavity vacuum degree 10 -4 The sputtering conditions for the interface metal were: argon pressure 0.75 Pa, sputtering power 10 kW, voltage 800 V, time 15 min, and temperature 300 °C; furnace chamber vacuum degree 10... -4 Pa, argon pressure 1.2 Pa, sputtering power 20 kW, voltage 700 V, time 90 min, temperature 320 °C; active metal layer thickness 850 nm; interface metal layer thickness 2 μm;

[0065] Step 3: Create through holes on the surface of the silicon nitride ceramic to obtain a silicon nitride ceramic insulating layer; silicon nitride ceramic: thickness 0.3 mm, surface roughness Ra 0.4 μm;

[0066] Step 4: Alternately stack the silicon nitride ceramic insulation layer and the metal wire layer obtained in Step 3 to assemble the coil semi-finished product. The assembly method is as follows: the tail end of the metal wire wound clockwise from the outside to the inside passes through the inner ring through hole on the silicon nitride ceramic insulation layer and is connected in series with the head end of the adjacent metal wire through the connecting wire. The tail end of the metal wire wound clockwise from the inside to the outside passes through the outer ring through hole on the silicon nitride ceramic insulation layer and is connected in series with the head end of the adjacent metal wire through the connecting wire. The coils of each metal wire layer and the silicon nitride ceramic insulation layer are connected in series. The number of metal wire layers is 25. The height of the coil connecting wire is 0.45mm.

[0067] Step 5: The coil semi-finished product obtained in Step 4 is subjected to high-temperature sintering to obtain the excitation coil; the high-temperature sintering process conditions are: temperature 1400℃, pressure 0.2MPa, time 40min.

[0068] Example 3: A method for preparing a high-reliability high-temperature excitation coil, comprising the following steps:

[0069] Step 1: Spiral wind the metal wire to form a metal coil; the metal wire thickness is 0.5mm, the metal coil width is 3mm, and the spacing between the wires is 0.5mm;

[0070] Step 2: The metal coil obtained in Step 1 is subjected to ion bombardment cleaning; then, an active metal is sputtered to form an active metal layer; an interface metal is sputtered to form an interface metal layer, resulting in a metal wire layer; the ion bombardment cleaning process conditions are: vacuum degree 1000 Pa, argon pressure 2.6 Pa, voltage 0.8 KV, cleaning time 300 s; the sputtering process conditions for the active metal are: furnace cavity vacuum degree 10 -3 The sputtering conditions for the interface metal were: argon pressure 1 Pa, sputtering power 15 kW, voltage 850 V, time 20 min, temperature 350 °C; furnace vacuum degree 10 Pa. -3 Pa, argon pressure 1.5 Pa, sputtering power 26 KW, voltage 750 V, time 100 min, temperature 380 ℃; active metal layer thickness 900 nm; interface metal layer thickness 3 μm;

[0071] Step 3: Create through holes on the surface of the silicon nitride ceramic to obtain a silicon nitride ceramic insulating layer; silicon nitride ceramic: thickness 0.4 mm, surface roughness Ra 0.6 μm;

[0072] Step 4: Alternately stack the silicon nitride ceramic insulation layer and the metal wire layer obtained in Step 3 to assemble the coil semi-finished product. The assembly method is as follows: the tail end of the metal wire wound clockwise from the outside to the inside passes through the inner ring through hole on the silicon nitride ceramic insulation layer and is connected in series with the head end of the adjacent metal wire through the connecting wire. The tail end of the metal wire wound clockwise from the inside to the outside passes through the outer ring through hole on the silicon nitride ceramic insulation layer and is connected in series with the head end of the adjacent metal wire through the connecting wire. The coils of each metal wire layer and the silicon nitride ceramic insulation layer are connected in series. The number of metal wire layers is 30. The height of the coil connecting wire is 0.55mm.

[0073] Step 5: The coil semi-finished product obtained in Step 4 is subjected to high-temperature sintering to obtain the excitation coil; the high-temperature sintering process conditions are: temperature 1880℃, pressure 0.3MPa, time 50min.

[0074] Comparative Example 1: Compared with Example 1, the silicon nitride ceramic was replaced with a commercially available high-temperature resistant ceramic, while the other conditions remained unchanged.

[0075] Comparative Example 2: Compared with Example 1, instead of using silicon nitride ceramic as the insulation layer, glass fiber wrapped around the metal wire was used as the insulation layer, while the other conditions remained the same.

[0076] Experiment: Excitation coils obtained in Examples 1-3 and Comparative Examples 1-2 were used to make samples, and their various properties were tested.

[0077] Thermal conductivity test: The thermal conductivity of the manufactured excitation coil was tested according to ASTM D5470.

[0078] Peel strength test: According to IPC-TM6502.4.8, apply an upward pressure of 90° at a speed of 80 mm / min and record the peel strength of the excitation coil.

[0079] Service life test: The excitation coil was subjected to a high temperature resistance test, and was used at 600℃. The number of times it was used before damage occurred was recorded.

[0080] The table below shows the test results for the thermal conductivity, peel strength, and service life of the excitation coil;

[0081] Thermal conductivity (W / m·K) Peel strength (N / mm) Number of times used Example 1 29.3 22 4790 Example 2 30.4 24 4860 Example 3 31.2 25 4930 Comparative Example 1 28.8 15 2540 Comparative Example 2 28.9 10 2430

[0082] Based on the data in the table above, the following conclusions can be clearly drawn:

[0083] The excitation coils obtained in Examples 1-3 are compared with those obtained in Comparative Examples 1-2. The test results show that...

[0084] Compared with Example 1, Comparative Examples 1-2 replaced the silicon nitride ceramic insulation layer with commercially available high-temperature resistant ceramic and used glass fiber wrapped metal wire as the insulation layer, respectively. The thermal conductivity, peel strength and service life of the excitation coils were significantly reduced. This is because the ceramic or glass fiber itself is brittle and the bending radius of the wound coil is large. Under long-term high operating temperature, it is easy to be damaged, thus affecting the service life of the excitation coil.

[0085] It is evident that the material settings in this application can improve the thermal conductivity, peel strength, and service life of the manufactured excitation coil.

[0086] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for preparing a high-reliability high-temperature excitation coil, characterized in that: Includes the following steps: Step 1: Wind the metal wire into a spiral to form a metal coil; Step 2: Perform ion bombardment cleaning on the metal coil obtained in Step 1; Then, an active metal is sputtered to form an active metal layer; an interface metal is sputtered to form an interface metal layer, thus obtaining a metal conductor layer. Step 3: Create through holes on the surface of the silicon nitride ceramic to obtain a silicon nitride ceramic insulating layer; Step 4: Alternately stack the silicon nitride ceramic insulation layer and the metal wire layer obtained in Step 3 to assemble and obtain a coil semi-finished product; Step 5: The coil semi-finished product obtained in Step 4 is sintered at high temperature to obtain a high-temperature excitation coil; In step 2, the sputtering process conditions for the reactive metal are: furnace cavity vacuum degree 10 -4 -10 -3 Pa, argon pressure 0.25-1 Pa, sputtering power 7-15 KW, voltage 750-850 V, time 10-20 min, temperature 250-350 ℃; In step 2, the sputtering process conditions for the interface metal are: furnace cavity vacuum degree 10 -4 -10 -3 Pa, argon pressure 0.8-1.5 Pa, sputtering power 16-26 KW, voltage 650-750 V, time 80-100 min, temperature 280-380 ℃.

2. The method for preparing a high-reliability high-temperature excitation coil according to claim 1, characterized in that: In step 5, the high-temperature sintering process conditions are: temperature 880-1880℃, pressure 0.1-0.3MPa, and time 30-50min.

3. The method for preparing a high-reliability high-temperature excitation coil according to claim 1, characterized in that: In step 2, the thickness of the reactive metal layer is 800-900 nm.

4. The method for preparing a high-reliability high-temperature excitation coil according to claim 1, characterized in that: In step 2, the thickness of the interface metal layer is 1-3 μm.

5. The method for preparing a high-reliability high-temperature excitation coil according to claim 1, characterized in that: In step 4, the number of metal conductor layers is 15-30.

6. A high-reliability high-temperature excitation coil, characterized in that: It includes a silicon nitride ceramic insulating layer and a metal conductor layer; the metal conductor layer includes a metal conductor and a metal layer disposed on the surface of the metal conductor; The metal layer includes an active metal layer and an interface metal layer. The active metal layer is one or more of Ti and Zr, and the interface metal layer is one or more of Cu, Ni and Ag. The metal wire is wound in a clockwise direction from the outside to the inside or from the inside to the outside; the metal wire layer is a multi-layered structure with the coils of adjacent metal wire layers running in opposite directions.

7. A high-reliability high-temperature excitation coil according to claim 6, characterized in that: The silicon nitride ceramic insulating layer is located between two adjacent metal conductor layers, and the silicon nitride ceramic insulating layer is provided with through holes; the tail end of the metal conductor passes through the through hole and is connected in series with the head end of the adjacent metal conductor through a connecting wire.

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