Preparation method of high-reliability high-temperature excitation coil

Abstract

The invention discloses a preparation method of a high-reliability high-temperature excitation coil, and relates to the technical field of magnetic suspension. The invention discloses a preparation method of a high-reliability high-temperature excitation coil. The preparation method comprises the following steps: firstly, winding a metal wire into a required multi-layer coil; the metal wire is subjected to ion bombardment cleaning, then active metal is sputtered on the surface of the metal wire, and then interface metal is sputtered; holes are formed in the surface of the silicon nitride ceramic to obtain a silicon nitride ceramic insulating layer with the holes, the insulating layer and a metal wire are assembled and then subjected to vacuum sintering, and the high-reliability high-temperature excitation coil of the multi-layer structure is obtained. Brazing of the metal wire and the silicon nitride ceramic is based on the AMB brazing process principle, the active metal layer sputtered on the surface of the metal wire is used for wetting the surface of the silicon nitride ceramic and reacts with the silicon nitride ceramic at the high temperature, the metal wire and the silicon nitride ceramic are tightly combined, reliability is better, and the manufactured high-temperature magnet exciting coil has the longer service life.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic suspension, in particular to a method for preparing a high-reliability high-temperature excitation coil. Background Art

[0002] With the rapid development of low-altitude economy and the demand for faster, higher, farther, more economical, more reliable and more environmentally friendly aircraft, compared with traditional mechanical bearings, there is no mechanical friction between the stator and rotor of the magnetic suspension bearing, the operating resistance is zero, no heat, no need for cooling and lubrication system, reduced volume and weight, suspended operation reduces mechanical noise and mechanical vibration, improves the stability of the entire fan, has higher reliability and service life, and has broad development space and application prospects in high-tech fields such as aerospace. At present, the excitation coil of high-temperature magnetic suspension bearings mostly uses high-temperature resistant insulating materials to wrap the wire, usually high-temperature resistant insulating materials include ceramics and glass fibers. During the winding process of the coil, due to the large turning radius of the coil and the high operating temperature, usually around 500-650℃, the long-term high temperature environment makes the insulation layer of the coil wire easily damaged, which greatly affects the service life of the coil. Summary of the invention

[0003] The object of the present invention is to provide a method for preparing a high-reliability high-temperature excitation coil to solve the problems raised in the prior art.

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

[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 outside to inside or clockwise from inside to outside; the metal wire layer is a multi-layer stacked arrangement, and the coil routing directions of two adjacent metal wire layers are opposite.

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

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

[0009] Step 1: spirally wind the metal wire to form a metal coil;

[0010] Step 2: ion bombarding and cleaning the metal coil obtained in step 1; then sputtering active metal to form an active metal layer; sputtering interface metal to form an interface metal layer to obtain a metal wire layer;

[0011] Step 3: drilling holes on the surface of the silicon nitride ceramic to form through holes, thereby obtaining a silicon nitride ceramic insulating layer;

[0012] Step 4: Alternately stacking the silicon nitride ceramic insulation layer and the metal conductor layer obtained in step 3, assembling them to obtain a semi-finished coil;

[0013] Step 5: The semi-finished coil obtained in step 4 is subjected to high temperature sintering to obtain a high temperature excitation coil.

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

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

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

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

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

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

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

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

[0022] Furthermore, the assembly method in step 4 is: the tail end of the metal wire wound clockwise from the outside to the inside passes through the inner circle 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, and the tail end of the metal wire wound clockwise from the inside to the outside passes through the outer circle 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, so that each layer of metal wire coils is connected in series with the silicon nitride ceramic insulation layer into one.

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

[0024] The connecting wire has a height of 0.35-0.55 mm.

[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° C., pressure 0.1-0.3 MPa, and time 30-50 min.

[0027] Furthermore, the metal wire is a silver wire or a nickel wire; the silver wire: purity 99.99%, sourced from Jiangsu Kangtian Alloy Materials Co., Ltd.;

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

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

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

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

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

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

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

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. The conventional excitation coil utilizes high temperature resistant ceramic or glass fiber to wrap a metal wire as an insulating layer. Due to the brittleness of the ceramic or glass fiber itself and the large turning radius of the wound coil, it is easy to be damaged under long-term high operating temperature (550-650°C), which affects the service life of the excitation coil. The structure of the excitation coil in the present invention adopts a layered structure, i.e., metal wire line + silicon nitride ceramic + metal wire line + silicon nitride ceramic + ... + metal wire line, and the insulating layer uses a sheet of silicon nitride ceramic. The metal wire does not need to be wrapped with ceramic or glass fiber, and there is no heat dissipation barrier layer on the surface of the metal wire, thereby increasing the heat dissipation effect of the metal wire.

[0037] 2. The brazing of metal wire and silicon nitride ceramic is based on the principle of AMB process (active metal brazing). The active metal layer sputtered on the surface of the metal wire is used to wet the surface of the silicon nitride ceramic and react with it at high temperature, so that the metal wire and silicon nitride ceramic are tightly bonded. The bonding layer is achieved by chemical reaction at high temperature. The bonding strength between the ceramic and the metal coil is high, with higher reliability and service life.

[0038] 3. On the one hand, the interface metal layer protects the active metal layer to prevent it from being oxidized and losing its activity, resulting in poor bonding between the metal wire and silicon nitride ceramics; on the other hand, copper will undergo a eutectic reaction with the metal wire, thereby reducing the sintering temperature. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

[0043] Figure 5 is a schematic cross-sectional view of a metal coil of the present invention;

[0044] Figure 6 This is a schematic diagram of laser cutting inner circle through holes of the silicon nitride ceramic insulation layer of the present invention;

[0045] Figure 7 This is a schematic diagram of laser cutting outer ring through holes of the silicon nitride ceramic insulation layer of the present invention;

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

[0047] Fig. 9 It is a schematic diagram of assembling a metal conductor and a silicon nitride ceramic insulating layer wound clockwise from the inside to the outside of the present invention;

[0048] Fig.10 It is a schematic diagram of the product structure of the present invention.

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

[0050] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] In the following specific implementations,

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

[0053] The active metal layer is titanium, titanium powder: 80 mesh, purity 99.7%, sourced from Beijing Xingrongyuan Technology Co., Ltd.

[0054] The interface metal layer is copper, copper powder: 80-300 mesh, purity 99%, from Hubei Dali Chemical Co., Ltd.;

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

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

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

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

[0059] Step 3: Open holes on the surface of silicon nitride ceramic to form through holes, and 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, and assemble them to obtain a semi-finished coil; the assembly method is: the tail end of the metal wire wound clockwise from the outside to the inside passes through the inner circle 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, and the tail end of the metal wire wound clockwise from the inside to the outside passes through the outer circle 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, and each layer of the metal wire coil is connected in series with the silicon nitride ceramic insulation layer; the number of metal wire layers is 15; the height of the connecting wire is 0.35 mm;

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

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

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

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

[0065] Step 3: Open holes on the surface of silicon nitride ceramic to form through holes, and 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, and assemble them to obtain a semi-finished coil; the assembly method is: the tail end of the metal wire wound clockwise from the outside to the inside passes through the inner circle 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, and the tail end of the metal wire wound clockwise from the inside to the outside passes through the outer circle 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, and each layer of the metal wire coil is connected in series with the silicon nitride ceramic insulation layer; the number of metal wire layers is 25; the height of the coil connecting wire is 0.45 mm;

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

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

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

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

[0071] Step 3: Open holes on the surface of silicon nitride ceramic to form through holes, and 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, and assemble them to obtain a semi-finished coil; the assembly method is: the tail end of the metal wire wound clockwise from the outside to the inside passes through the inner circle 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, and the tail end of the metal wire wound clockwise from the inside to the outside passes through the outer circle 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, and each layer of the metal wire coil is connected in series with the silicon nitride ceramic insulation layer; the number of metal wire layers is 30; the height of the coil connecting wire is 0.55 mm;

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

[0074] Comparative Example 1: Using Example 1 as a comparison, the silicon nitride ceramic is replaced with a commercially available high temperature resistant ceramic, and the other conditions remain unchanged.

[0075] Comparative Example 2: Taking Example 1 as a comparison, instead of using silicon nitride ceramic as the insulating layer, glass fiber wrapped metal wire is used as the insulating layer, and other conditions remain unchanged.

[0076] Experiment: The excitation coils obtained in Examples 1-3 and Comparative Examples 1-2 were made into samples, and their properties were tested;

[0077] Thermal conductivity test: According to ASTM D5470, the thermal conductivity test of the prepared excitation coil was carried out;

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

[0079] Service life test: Conduct a high temperature resistance test on the prepared excitation coil, use it at 600℃, and record the number of times it is used when damage occurs;

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

[0081] Thermal conductivity (W / m·K) Peel strength (N / mm) Use times (times) 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] According to the data in the above table, we can clearly draw the following conclusions:

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

[0084] Compared with Example 1, in Comparative Examples 1-2, the silicon nitride ceramic insulation layer is replaced with commercially available high-temperature resistant ceramic and the glass fiber wrapped metal wire is used as the insulation layer, respectively. The thermal conductivity, peel strength and service life of the obtained excitation coil are significantly reduced. The reason is that the ceramic or glass fiber itself is brittle and the bending radius of the wound coil is large, which is easy to be damaged under long-term high temperature, thereby affecting the service life of the excitation coil;

[0085] It can be seen that the material settings used in this application can promote the improvement of 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 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 the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A high-reliability high-temperature excitation coil, characterized in that: It includes a silicon nitride ceramic insulating layer and a metal wire layer; the metal wire layer includes a metal wire and a metal layer arranged on the surface of the metal wire; 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.

2. A high-reliability high-temperature excitation coil according to claim 1, characterized in that: The winding direction of the metal wire is clockwise from outside to inside or clockwise from inside to outside; the metal wire layer is a multi-layer stacked arrangement, and the coil routing directions of two adjacent metal wire layers are opposite.

3. The high-reliability high-temperature excitation coil according to claim 1, characterized in that: The silicon nitride ceramic insulation layer is located between two adjacent metal wire layers, and the silicon nitride ceramic insulation layer is provided with a through hole; the tail end of the metal wire passes through the through hole and is connected in series with the head end of the adjacent metal wire through a connecting wire.

4. A method for preparing a high-reliability high-temperature excitation coil, characterized in that: The following steps are involved: Step 1: spirally wind the metal wire 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, and a metal conductor layer is obtained; Step 3: drilling holes on the surface of the silicon nitride ceramic to form through holes, thereby obtaining a silicon nitride ceramic insulating layer; Step 4: Alternately stacking the silicon nitride ceramic insulation layer and the metal conductor layer obtained in step 3, assembling them to obtain a semi-finished coil; Step 5: The semi-finished coil obtained in step 4 is subjected to high temperature sintering to obtain a high temperature excitation coil.

5. The method for preparing a high-reliability high-temperature excitation coil according to claim 4, characterized in that: In step 5, the process conditions for high temperature sintering are: temperature 880-1880° C., pressure 0.1-0.3 MPa, and time 30-50 min.

6. The method for preparing a high-reliability high-temperature excitation coil according to claim 4, characterized in that: In step 2, the sputtering process conditions of the active metal are: the vacuum degree of the furnace is 10 -4 -10 -3 Pa, argon pressure 0.25-1Pa, sputtering power 7-15KW, voltage 750-850V, time 10-20min, temperature 250-350℃.

7. The method for preparing a high-reliability high-temperature excitation coil according to claim 4, characterized in that: In step 2, the sputtering process conditions of the interface metal are: the vacuum degree of the furnace is 10 -4 -10 -3 Pa, argon pressure 0.8-1.5Pa, sputtering power 16-26KW, voltage 650-750V, time 80-100min, temperature 280-380℃.

8. The method for preparing a high-reliability high-temperature excitation coil according to claim 4, characterized in that: In step 2, the thickness of the active metal layer is 800-900 nm.

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

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

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