Multilayer susceptor composite material and preparation method therefor

Abstract

The present invention relates to a multilayer susceptor composite material, which comprises: first susceptor materials; and a second susceptor material, the second susceptor material being located between the first susceptor materials. The first susceptor materials are configured to be in close physical contact with the second susceptor material; the second susceptor material has a Curie temperature lower than that of the first susceptor materials, and the second susceptor material has a Curie temperature of lower than 600℃; a transition layer is provided between a first susceptor material and the second susceptor material. Implementing the technical solution can achieve the following technical effects: multi-temperature-interval control and the multilayer susceptor composite material allowing for self-feedback closed-loop control enable accurate temperature control, and mature preparation equipment and process allow for mass production and ensure stable performance and good consistency, thus greatly reducing the cost.

Description

A multilayer susceptor composite material and preparation method thereof Technical Field

[0001] The present invention relates to the technical field of electromagnetic induction heating multilayer susceptor composite materials, and in particular to a multilayer susceptor composite material for electromagnetic induction heating, a preparation process and applications thereof. Background Art

[0002] At present, the conventional heating method is to directly physically connect the heating element and the power supply of the heater product. This type of resistance heating method is direct and simple, but the heated material will contaminate the heating element and the heater product. The pollutants will cause odor and corrode the heating element under high temperature, thus affecting the lifespan and experience. At the same time, it is difficult to clean and the operation can easily damage the heating element. Electromagnetic induction non-contact precise temperature control heating method can avoid such problems.

[0003] Many induction heaters currently available on the market do not have a direct means of measuring the temperature inside the heating element itself, which means that they cannot accurately control the temperature of the heating element through self-feedback.

[0004] Iron-based alloys have high magnetic permeability and a fast electromagnetic induction heating rate. Therefore, wireless temperature control sensors are generally made of iron or iron-based alloys, the most typical material being stainless steel. Sensors made of a single stainless steel material suffer from low temperature control precision, or even inaccurate temperature control. Iron-based alloys, including stainless steel, have very high Curie temperatures. Therefore, when a single layer of iron-based alloy is used as a sensor, it can only provide heating and cannot be limited to a maximum temperature by the material's inherent properties. The Curie temperature of typical SUS430 / SUS410 / SUS444 stainless steel is above 700°C. In some applications below 700°C, a temperature threshold control program must be added to the microcontroller, which greatly complicates the structure of the induction heating device.

[0005] Summary of the Invention

[0006] The present invention provides a multi-layer susceptor composite material and a preparation method thereof, which solves the problems of the existing model.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A multilayer susceptor composite material, characterized by comprising: first susceptor materials 1, 4 and a second susceptor material 3, wherein the second susceptor material 3 is located between the first susceptor materials 1, 4, and the first susceptor materials 1, 4 are arranged in close physical contact with the second susceptor material 3; the second susceptor material 3 has a Curie temperature lower than that of the first susceptor materials 1, 4, and the second susceptor material 3 has a Curie temperature lower than 600°C; and a transition layer 2 is provided between the first susceptor material 1 and the second susceptor material 3.

[0009] The second susceptor material preferably has a Curie temperature below 450°C. The first susceptor material preferably serves primarily to heat the susceptor when placed in a fluctuating electromagnetic field. Any suitable material may be used. For example, the first susceptor material may be aluminum, or iron or an iron alloy such as ferritic stainless steel. The second susceptor material preferably serves primarily to indicate when the susceptor has reached a specific temperature, which is the Curie temperature of the second susceptor material. The Curie temperature of the second susceptor material can be used to regulate the temperature of the entire susceptor during operation. Suitable materials for the second susceptor material may include nickel and certain nickel alloys or iron-nickel alloys.

[0010] The first susceptor material can be selected based on optimization of heating efficiency, while the second susceptor material can be selected based on optimization of temperature range control. The first susceptor material can be set to a maximum desired heating temperature, while the second susceptor material can be selected to have a Curie temperature or a second Curie temperature corresponding to the predetermined maximum desired heating temperature of the first susceptor material. The first and second susceptor materials and the transition layer form a composite material with a monolithic structure. This can be referred to as a dual-material susceptor or a multi-material susceptor.

[0011] Preferably, inductive heating of the magnetic susceptor material within the fluctuating magnetic field occurs through a combination of resistive heating due to eddy currents induced in the susceptor and heat generated by hysteresis losses. Preferably, the first susceptor material is a ferromagnetic metal having a Curie temperature exceeding 700°C. Preferably, the first susceptor is iron or an iron alloy (such as steel) or an iron-nickel alloy. It may be particularly preferred that the first susceptor material be a 400 series ferritic stainless steel, such as SUS410, SUS420, SUS430, or SUS443. SUS430 stainless steel is a ferromagnetic material having a Curie temperature exceeding 700°C.

[0012] Preferably, the second susceptor material is a soft magnetic alloy with a Curie temperature lower than 400 degrees, preferably a detectable Curie temperature between 200-400 degrees, such as nickel or iron-nickel alloy, such as Chinese brands N6, N4, 1J50, 1J79, 1J85, etc.

[0013] Comprising a structure of at least three or more layers, including a first susceptor material layer (two layers, A and B), a second susceptor material layer, and a transition layer, the multilayer susceptor composite material of the present invention simultaneously provides heating and precise temperature control. Due to the formation of a closed-loop feedback loop, temperature control is highly accurate, resolving the problem of existing heating materials on the market being unable to achieve non-contact, self-feedback closed-loop temperature control to within 10 degrees Celsius.

[0014] The multilayer susceptor composite material provided by the present invention comprises a transition layer between the first and second susceptor material layers. This transition layer enhances composite strength, facilitates rapid thermal equilibrium, and improves the thermal stability of the susceptor. The first and second susceptor materials exhibit significant physical differences, and the transition layer acts as a buffer, thereby overcoming these differences in physical properties, particularly the difference in thermal expansion coefficients, and preventing delamination and deformation. This ensures the stability and consistency of the multilayer susceptor composite material throughout the heating process, overcoming the problem of existing commercially available materials that are prone to delamination and peeling during long-term heating.

[0015] Preferably, the first susceptor materials 1 and 4 are iron, an iron alloy, or stainless steel; the second susceptor material 3 is nickel, a nickel alloy, or an iron-nickel alloy; and the transition layer material is nickel, iron, zinc, or copper. The transition layer between the first and second susceptor material layers preferably comprises a metal element or alloy thereof with high thermal and electrical conductivity, preferably nickel, iron, cobalt, copper, aluminum, zinc, silver, or other alloys.

[0016] Preferably, the thickness of the composite susceptor material is between 10 and 1000 microns, and the Curie temperature of the second susceptor material 3 is less than 400°C. The first and second susceptor materials are brought into close contact, or through a transition layer, to form an atomically diffused monolithic susceptor. This is achieved through a combination of hot and cold rolling processes, such as the hot rolling and pressing unit shown in Figure 3. This facilitates mass production and significantly reduces manufacturing costs.

[0017] Preferably, the thickness of the susceptor composite material is between 10-500 microns. The preferred thickness of the first susceptor material A layer is 15-300 microns;

[0018] In the multi-layer susceptor composite material provided by the present invention, the preferred thickness of the first susceptor material B layer is 5-150 microns;

[0019] In the multi-layer susceptor composite material provided by the present invention, the preferred thickness of the second susceptor material layer is 10-250 microns;

[0020] In the multi-layer susceptor composite material provided by the present invention, the preferred thickness of the transition material layer is 1-50 microns.

[0021] The multilayer susceptor composite material provided by the present invention can adjust and control the magnetic strength and resistance by adjusting and limiting the thickness of each layer, and can also avoid the transition layer from affecting the induction heating characteristics of the first susceptor material layer and the second susceptor material layer.

[0022] Preferably, the multilayer susceptor material is in the form of a sheet, strip, foil, rod, tube, cup, or pot. By regulating the metal phase composition of the first susceptor material (which also has a high Curie temperature point) and the second susceptor material (which also has a low Curie temperature point), the required operating temperature range can be met, Curie temperature detection can be performed, and characteristic current values, characteristic temperature values, and maximum threshold temperature can be regulated.

[0023] The multilayer susceptor composite material provided by the present invention is suitable for various applications of induction heating, especially scenarios requiring induction heating and precise temperature control, including but not limited to susceptor heating materials for induction heating aerosols for electronic cigarettes, susceptor heating materials for aerosols for medical atomization, constant temperature wireless control heating materials for the chemical industry, or beauty devices, etc.

[0024] The logic behind the precise temperature control embodiment of the multilayer susceptor composite material provided by the present invention is as follows: the first and second susceptor materials are in close contact, or in close contact through a transition layer, to form an atomically diffused integral susceptor. Therefore, when induction heating is initiated, the first and second susceptor materials have the same temperature. As the temperature rises, when the entire susceptor reaches the second Curie temperature, the magnetic properties of the second susceptor material change, reversibly transforming from a ferromagnetic phase to a paramagnetic phase at the second Curie temperature. This phase transition of the second susceptor material can be detected during induction heating without requiring physical contact with the material. A minimum resistance value is observed near the Curie temperature of the second susceptor material, and this minimum resistance value is used to calibrate the temperature at a specific point, achieving temperature control. Since the phase transition from the ferromagnetic phase to the paramagnetic phase can be detected, the heating temperature can be controlled. When the phase transition associated with the second Curie temperature is detected, induction heating can be automatically stopped. After induction heating ceases, the entire susceptor cools until it reaches a temperature below the second Curie temperature. At this point, the second susceptor material regains its ferromagnetic properties, undergoing a phase transition. The resistance change associated with this phase transition can be indirectly measured by measuring the current used to generate the fluctuating magnetic field. Induction heating is then reactivated. Therefore, the induction heating device can be repeatedly activated and deactivated to control the induction heating temperature, achieving self-feedback closed-loop, non-contact, and precise temperature control.

[0025] As used herein, the term "susceptor composite" refers to a material that can convert electromagnetic energy into thermal energy. When placed in a fluctuating electromagnetic field, eddy currents and hysteresis losses induced in the susceptor composite result in heating of the susceptor composite.

[0026] The multilayer susceptor composite material provided herein may include a protective outer layer, such as a protective ceramic layer or a protective glass layer, encapsulating the first and second susceptor materials. The susceptor may include a protective layer formed from glass, ceramic, or an inert metal, or electroplated nickel, zinc, or the like, formed on a core comprising the first and second susceptor materials.

[0027] Preferably, the multilayered susceptor composite material provided by the present invention is used in a self-feedback closed-loop control system for heating. Thus, when the electronic circuit detects that the susceptor temperature has increased above the second Curie temperature, it can shut off the fluctuating magnetic field. When the susceptor temperature decreases below the second Curie temperature, it can re-enable the magnetic field. Thus, the susceptor temperature can be maintained at the second Curie temperature plus or minus 20°C for a predetermined period of time. Thus, the closed-loop control system allows the susceptor temperature to be controlled within the second Curie temperature plus or minus 10°C, preferably within the second Curie temperature plus or minus 5°C.

[0028] Preferably, the second susceptor material 3 is hot-rolled and laminated to the first susceptor materials 1 and 4, followed by diffusion annealing and cold rolling to achieve the final thickness of the composite material. The present invention provides a novel method for preparing a multilayer composite susceptor material by combining hot-rolled lamination with cold rolling. The composite strip produced by this method has high bonding strength and a truly integrated structure. The hot-rolling and atomic diffusion annealing processes allow inter-layer atomic diffusion at the bonding interface to achieve ultra-high peel strength. This prevents the composite material from delamination, peeling, or deformation during use, such as during heating, ensuring the overall consistency and stability of the multilayer composite material and a long service life.

[0029] Preferably, the first susceptor materials 1, 4 and the second susceptor material 3 are jointly hot-rolled and cold-rolled in the form of multi-layer strips, with the first susceptor materials 1, 4 having a greater thickness than the second susceptor material 3. The multi-layer susceptor composite material provided by the present invention has a transition layer with adjustable thickness as needed, down to 1 micron. Due to the hot-rolling and cold-rolling process, the thickness uniformity of the transition layer between the first and second susceptor layers is very high, thus ensuring consistent material properties during mass production and resolving the difficulty of achieving both thinness and uniformity in other processes.

[0030] Preferably, the first susceptor materials 1 and 4 are used for heating, and the second susceptor material 3 is used to determine when the first susceptor materials 1 and 4 reach a temperature corresponding to the Curie temperature of the second susceptor material. The multilayer susceptor composite material provided by the present invention utilizes a combined hot-rolling and cold-rolling process to precisely control the thickness of the first and second susceptor layers, as well as the transition layer, down to the micron level. This fully utilizes the temperature-control properties of the first and second susceptor materials, preventing the influence of thickness differences on the time point of reaching the Curie temperature, thereby achieving precise temperature control and better ensuring the consistency of the finished product.

[0031] A method for preparing a multilayer susceptor composite material, characterized in that it comprises the following steps:

[0032] S1. Select raw materials according to the composition of each layer of the susceptor: a first susceptor strip with a thickness of 0.5-3.0 mm, a second susceptor strip with a thickness of 0.5-1.5 mm, and a transition layer strip with a thickness of 0.1-1.0 mm;

[0033] S2. First surface treatment: grinding, polishing, cleaning and drying the first susceptor strip, the second susceptor strip and the transition layer strip;

[0034] S3, hot rolling composite treatment: heating the first susceptor strip and the second susceptor strip respectively, and making the first susceptor strip and the second susceptor strip enter the hot rolling mill at 150-300° C. for hot rolling composite treatment;

[0035] Specifically, the first susceptor strip, the second susceptor strip, and the transition layer strip are heated separately and simultaneously placed in a hot press assembly for pressing. During the heating and calendering composite process of the first susceptor strip, the second susceptor strip, and the transition layer strip, an inert gas or ammonia decomposition gas is introduced to form a susceptor composite material.

[0036] S4, second surface treatment: grinding, polishing, cleaning and drying the susceptor composite material;

[0037] S5, diffusion annealing: subjecting the surface treated susceptor composite material to one or more diffusion annealing processes at a temperature of 700-1000°C;

[0038] S6, cold rolling treatment: performing multiple cold rolling on the annealed susceptor composite material;

[0039] Between any two cold rolling processes of the susceptor composite material, the susceptor composite material is subjected to one or more softening annealing treatments, wherein the softening annealing temperature is between 700° C. and 1100° C.;

[0040] Repeatedly annealing and cold rolling until the thickness of the susceptor composite material is 10-500 microns;

[0041] S7, flattening and cutting the susceptor composite material.

[0042] By implementing the above technical solution, the following technical effects are achieved: multi-temperature range control, self-feedback closed-loop control of multi-layer susceptor composite materials, precise temperature control, mature preparation equipment and process, mass production, stable performance, good consistency, and greatly reduced costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] FIG1 is a schematic cross-sectional view of a multi-layer susceptor composite material provided by the present invention, wherein layers 1 and 4 are first susceptor layers, layer 2 is a transition layer, and layer 3 is a second susceptor layer;

[0044] FIG2 is a schematic diagram illustrating the relationship between resistance and temperature. When the second susceptor material is inductively heated, a remotely detectable resistance change occurs when the second susceptor material undergoes a phase transition associated with its Curie temperature as the temperature changes.

[0045] Figure 3 is a schematic diagram of a hot rolling composite process unit;

[0046] FIG4 is a schematic diagram showing the relationship between the resistance and temperature of the first susceptor material in a typical preferred embodiment;

[0047] FIG5 is a schematic diagram of a cross section of a three-layer composite susceptor material. DETAILED DESCRIPTION

[0048] In order to better understand the technical solution of the present invention, the embodiments provided by the present invention are described in detail below with reference to the accompanying drawings.

[0049] Induction heating is a known phenomenon described by Faraday's law of induction and Ohm's law. Conductors that can be heated by induction are called susceptors.

[0050] The overall multi-layer susceptor for electromagnetic induction heating according to an embodiment of the present invention has a typical application thickness of 10-500 microns, and preferably a thickness of 30-300 microns.

[0051] The implementation of the present invention is described below with reference to specific embodiments:

[0052] The first embodiment of the present invention provides a four-layer susceptor composite material, as shown in Figure 1, comprising a first susceptor material (stainless steel SUS430), comprising an upper surface (stainless steel SUS430) and a lower surface (stainless steel SUS430), a second susceptor material (iron-nickel alloy 1J85 or 1J79), and a transition layer (nickel or iron). The preparation method includes the following steps:

[0053] Step S101: Select the raw materials for the first sensor surface A and surface B. Select ferritic stainless steel, such as SUS430 strip or SUS443 strip, with a thickness of 1-3 mm (e.g., 1 mm, 2 mm, or 3 mm), a width of 90-300 mm (e.g., 100 mm, 120 mm, 200 mm), and a hardness of 130-170 HV.

[0054] Step S102 , selecting a second susceptor raw material, selecting an iron-nickel alloy (e.g. 1J50 or 1J79, or 1J85) strip with a thickness of 0.5-2 mm (e.g. 1 mm, 1.5 mm, 2 mm), a width of 90-300 mm (e.g. 100 mm, 120 mm, 200 mm), and a hardness of 120-160 HV.

[0055] Step S103 selects a transition layer material. A pure nickel (e.g., Chinese brand N6) strip or pure iron strip with a thickness of 0.3-1 mm (e.g., 0.3 mm, 0.5 mm, 1 mm) and a width of 90-300 mm (e.g., 100 mm, 120 mm, 200 mm) is selected. The hardness is 90-120 HV. Nickel is a ferromagnetic material with a Curie temperature of approximately 354°C.

[0056] Step S104 , performing surface polishing, cleaning, and drying on the selected raw materials to remove the oxide layer and eliminate surface defects such as scratches and dents to ensure that the surface quality meets the requirements of the composite material.

[0057] Step S105, hot pressing and laminating: the selected raw materials are subjected to calendering and lamination, and the first susceptor material layer A and the transition layer are heated separately to provide a certain amount of thermal energy to the materials so that the temperature of the raw material strip is controlled between 150-400 degrees. The first susceptor material layer A and the transition layer material are simultaneously fed into a hot rolling mill for hot rolling and lamination to obtain a composite strip with two layers laminated as a whole. The two laminated susceptor materials are bent back and forth 90 degrees. The lamination is qualified if there is no delamination.

[0058] Step S106, hot pressing and laminating: The first susceptor material layer B and the second susceptor material are heated simultaneously to provide a certain amount of thermal energy to the materials so that the temperature of the raw material strip is controlled between 150 and 400 degrees. The first susceptor material layer B and the second susceptor material are simultaneously fed into a hot rolling mill for hot rolling and laminating to obtain a composite strip with two layers laminated together. The laminated two layers of susceptor material are bent back and forth 90 degrees. The lamination is qualified if there is no delamination.

[0059] Preferably, when the raw materials are rolled and compounded by the hot rolling compounding unit, inert gas or ammonia decomposition gas N2, H2 is introduced into the unit heating device and the compounding unit, so that the first susceptor material, the transition layer material and the second susceptor material are rolled and compounded in an inert gas or reducing atmosphere to prevent oxidation of the materials during heating, thereby ensuring the bonding strength between the layers.

[0060] Step S107, surface treatment such as polishing: polish the surfaces of the two composite susceptor materials using a polishing device to remove surface debris, eliminate surface defects (such as scratches, peeling, and pressure points) generated during the raw materials or processing, and then clean and dry.

[0061] Step S108, diffusion annealing treatment, diffusion annealing treatment is performed on the two composite strips after grinding. The diffusion annealing temperature is 700-1000 degrees (for example, 700 degrees, 800 degrees or 900 degrees). Different temperatures are selected for different rolling processes. Diffusion annealing can make the atoms at the bonding interface between the material layers diffuse with each other, thereby enhancing the composite interface bonding force and increasing the composite strength of the susceptor composite strip.

[0062] Step S109, hot pressing and laminating: The composite strip of the first susceptor material layer A and the transition layer, and the composite strip of the first susceptor material layer B and the second susceptor material are heated simultaneously, providing a certain amount of heat energy to both composite strips so that the temperature of the raw material strips is controlled between 200 and 500 degrees. The composite strip of the first susceptor material layer A and the transition layer, and the composite strip of the first susceptor material layer B and the second susceptor material simultaneously enter the hot rolling unit for hot rolling and laminating to obtain a composite strip with four layers laminated as a whole. The four layers of susceptor material after lamination are bent back and forth 90 degrees. The lamination is qualified if there is no delamination.

[0063] In step S110 , the four-layer composite strip is subjected to surface treatments such as grinding and polishing to remove surface debris and defects, and then cleaned and dried.

[0064] Step S111, a second diffusion annealing treatment is performed on each of the four layers of composite strips after grinding and polishing, with the annealing temperature being 700-1000 degrees, preferably 700-900 degrees.

[0065] Step S112, cold rolling treatment: a multi-roller cold rolling mill is used to perform multiple passes of rolling on the four-layer susceptor composite strip after the second diffusion annealing until the desired thickness of the finished product is reached, for example, 50-120 microns.

[0066] In step S113 , preferably, the cold-rolled four-layer susceptor composite strip is cleaned and dried.

[0067] Step S114, preferably, one or more softening annealing treatments are required between any two cold rollings of the susceptor composite strip. The annealing temperature is between 700-1100 degrees, and different temperatures are selected according to different thicknesses. Multiple cold rollings will produce work hardening, and soft annealing is performed before cold rolling to eliminate the work hardening.

[0068] Step S115: cold rolling, annealing, and cleaning are repeated in multiple rounds until the desired finished product thickness is reached.

[0069] Step S116: leveling and cutting the finished susceptor composite strip.

[0070] The first embodiment of the present invention has high production efficiency, is easy to mass-produce, and has tight integration.

[0071] FIG5 is a cross-sectional view of the second embodiment of the present invention. The processing process includes the following steps:

[0072] Step S201 , polishing and cleaning treatment, respectively polishing and cleaning the surfaces of the selected first susceptor material layer A, the second susceptor material, and the first susceptor material layer B to remove surface oxides, impurities and defects, and then cleaning and drying.

[0073] Step S202, hot pressing and laminating: The first susceptor layer A, the second susceptor material, and the first susceptor material layer B strips are heated simultaneously, providing a certain amount of heat energy to all three strips to control the temperature of the raw strips between 200 and 500 degrees. The first susceptor material layer A, the first susceptor layer B, and the second susceptor material strip are simultaneously fed into a hot rolling mill for hot rolling and lamination to obtain a composite strip with three layers laminated as a whole. The three laminated susceptor materials are then bent back and forth 90 degrees. The lamination is qualified if there is no delamination.

[0074] Step S203: surface treatment such as grinding and polishing.

[0075] Step S204: Diffusion annealing treatment: Diffusion annealing treatment is performed on the three layers of composite strip after grinding and polishing, and the diffusion annealing temperature is 700-1000 degrees.

[0076] Step S205: cold rolling and calendering treatment, using multi-roller multi-pass cold rolling and calendering.

[0077] Step S206: cold rolling, annealing, and cleaning are repeated in multiple rounds until the desired finished product thickness is reached, for example, 30-200 mm thick.

[0078] The second embodiment of the present invention has a simple structure and low raw material cost.

[0079] Based on the first embodiment of the present invention, a third embodiment is proposed, which provides a five-layer susceptor composite material, the processing process of which includes the following steps:

[0080] Step S301: Two rolls of SUS430 material (the first susceptor material) are selected. Layers A and B are applied to the upper and lower outer surfaces of the entire susceptor, respectively. One roll of 1J85 iron-nickel alloy (the second susceptor material) is selected, along with two rolls of pure nickel tape for the transition layer. Each of the five selected rolls undergoes a polishing and cleaning process to remove surface oxides, debris, and defects, followed by cleaning and drying.

[0081] Step S3021, hot pressing and laminating treatment 1: The first susceptor material layer A and the transition layer strip are heated simultaneously, providing a certain amount of heat energy to both strips to keep the temperature of the raw material strip between 200-500 degrees. The first susceptor material layer A and the transition layer material strip are simultaneously fed into a hot rolling mill for hot rolling and laminating to obtain a composite strip with two layers laminated as a whole. The laminated two layers of susceptor material are bent back and forth 90 degrees. The lamination is qualified if there is no delamination.

[0082] Step S3022, hot pressing and laminating treatment 2: The first susceptor layer B and the transition layer strip are heated simultaneously, providing a certain amount of heat energy to both strips to keep the temperature of the raw strips between 200-500 degrees. The first susceptor material layer B and the transition layer material strip are simultaneously fed into a hot rolling mill for hot rolling and laminating to obtain a composite strip with two layers laminated together. The laminated two layers of susceptor material are bent back and forth 90 degrees. The lamination is qualified if there is no delamination.

[0083] Step S3023, hot pressing and laminating treatment 3: The strip after lamination in step S3021, the strip after lamination in step S3022, and the second susceptor strip (set as the middle layer) are heated simultaneously, providing a certain amount of heat energy to all three strips so that the temperature of the raw material strip is controlled between 200 and 500 degrees. The three strips are simultaneously fed into the hot rolling mill for hot rolling and lamination to obtain a composite strip with five layers laminated as a whole. The five layers of susceptor material after lamination are bent back and forth 90 degrees, and the lamination is qualified if there is no delamination.

[0084] Step S303: surface treatment such as grinding and polishing.

[0085] Step S304: Diffusion annealing treatment: Diffusion annealing treatment is performed on the three layers of composite strip after grinding and polishing, and the diffusion annealing temperature is 700-1000 degrees.

[0086] Step S305: cold rolling and calendering treatment, using multi-roller multi-pass cold rolling and calendering.

[0087] Step S306: cold rolling, annealing, and cleaning are repeated in multiple rounds until the desired finished product thickness is reached, for example, 30-200 mm.

[0088] Step S307 : Flatten and cut the multi-layer susceptor material at the finished thickness to the size required for the application.

[0089] The above is a detailed introduction to a multilayer susceptor composite material and its preparation method provided in an embodiment of the present invention. For those skilled in the art, based on the ideas of the embodiments of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A multilayer susceptor composite material, characterized in that: include: a first susceptor material (1, 4) and a second susceptor material (3), the second susceptor material (3) being located between the first susceptor materials (1, 4), the first susceptor material (1, 4) being arranged in close physical contact with the second susceptor material (3); The second susceptor material (3) has a Curie temperature lower than that of the first susceptor material (1, 4), and the second susceptor material (3) has a Curie temperature lower than 600° C.; A transition layer (2) is provided between the first susceptor material (1) and the second susceptor material (3).

2. The multilayer susceptor composite material according to claim 1, characterized in that: The first susceptor material (1, 4) is iron or iron alloy or stainless steel, the second susceptor material (3) is nickel or nickel alloy or iron-nickel alloy, and the transition layer material is nickel, iron, zinc or copper.

3. The multilayer susceptor composite material according to claim 1, characterized in that: The thickness of the susceptor composite material is between 10 and 1000 micrometers, and the application Curie temperature of the second susceptor material (3) is lower than 400°C.

4. The multilayer susceptor composite material according to claim 3, wherein: The thickness of the susceptor composite material is between 10 and 500 microns.

5. The multilayer susceptor composite material according to claim 1, wherein: The multilayer susceptor material is in the form of a sheet, a tape, a foil, a rod, a tube, a cup or a pot.

6. The multilayer susceptor composite material according to claim 1, wherein: The second susceptor material (3) is composited onto the first susceptor material (1, 4) by a hot rolling process, and then diffusion annealing and cold rolling are performed to form the composite susceptor material to the finished product thickness.

7. The multilayer susceptor composite material according to claim 1, wherein: The first susceptor material (1, 4) and the second susceptor material (3) are hot rolled and cold rolled together in the form of a multi-layer strip, and the first susceptor material (1, 4) has a greater thickness than the second susceptor material (3).

8. The multilayer susceptor composite material according to claim 1, wherein: The first susceptor material (1, 4) is used for heating, and the second susceptor material (3) is used for determining when the first susceptor material (1, 4) reaches a temperature corresponding to the Curie temperature of the second susceptor material.

9. A method for preparing a multilayer susceptor composite material, characterized in that: The following steps are involved: S1. Select raw materials according to the composition of each layer of the susceptor: a first susceptor strip with a thickness of 0.5-3.0 mm, a second susceptor strip with a thickness of 0.5-1.5 mm, and a transition layer strip with a thickness of 0.1-1.0 mm; S2. First surface treatment: grinding, polishing, cleaning and drying the first susceptor strip, the second susceptor strip and the transition layer strip; S3, hot rolling composite treatment: heating the first susceptor strip and the second susceptor strip respectively, and making the first susceptor strip and the second susceptor strip enter the hot rolling mill at 150-300° C. for hot rolling composite treatment; Specifically, the first susceptor strip, the second susceptor strip, and the transition layer strip are heated separately and simultaneously placed in a hot press assembly for pressing. During the heating and calendering composite process of the first susceptor strip, the second susceptor strip, and the transition layer strip, an inert gas or ammonia decomposition gas is introduced to form a susceptor composite material. S4, second surface treatment: grinding, polishing, cleaning and drying the susceptor composite material; S5, diffusion annealing: subjecting the surface treated susceptor composite material to one or more diffusion annealing processes at a temperature of 700-1000°C; S6, cold rolling treatment: performing multiple cold rolling on the annealed susceptor composite material; Between any two cold rolling processes of the susceptor composite material, the susceptor composite material is subjected to one or more softening annealing treatments, wherein the softening annealing temperature is between 700° C. and 1100° C.; Repeatedly annealing and cold rolling until the thickness of the susceptor composite material is 10-500 microns; S7, flattening and cutting the susceptor composite material.

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