A magnetic conducting plate assembly, a sound production device and an electronic device

Abstract

This invention discloses a magnetically conductive plate assembly, a sound-generating device, and an electronic device, relating to the field of acoustic technology. The magnetically conductive plate assembly includes a body and a plating layer disposed on the surface of the body. The plating layer is primarily a polycrystalline material composed of Ni and Co elements. The polycrystalline material has at least one of a face-centered cubic structure and a close-packed hexagonal crystal structure. The average grain size of the plating layer is 0.01~15 μm, and the self-corrosion potential of the plating layer in a 3.5 wt.% NaCl solution is -0.7~-0.1 V. The magnetically conductive plate assembly of this invention aims to solve the technical problem of improving the magnetic permeability of the magnetically conductive plate assembly while ensuring its corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of acoustics, and more particularly to a magnetic plate assembly, a sound-generating device, and an electronic device. Background Technology

[0002] As a core sound-generating component in consumer electronics products such as mobile phones and AR (Augmented Reality) glasses, the thickness of loudspeakers is decreasing to keep pace with the trend of ultra-thin and lightweight electronic products. The magnetic circuit structure (i.e., the magnetic circuit system) is a crucial source of driving force for loudspeakers and directly affects their frequency response characteristics. Typically, the magnetic circuit structure includes a frame, a magnet mounted on the frame, and a washer mounted on the magnet. The magnet is a permanent magnet used to provide the magnetic field; the frame and washer are made of soft magnetic materials and serve to conduct the magnetic flux, together forming the magnetic circuit.

[0003] Basin frames and washers are mostly made of iron-based materials such as SPCC (cold-rolled steel sheet), which are prone to oxidation under harsh environments such as high temperature, high humidity, and salt spray, forming non-magnetic oxides such as Fe2O3 on the surface, resulting in a significant decrease in overall magnetic permeability. Therefore, it is usually necessary to add a coating to the surface of the basin frame or washer to provide corrosion protection. However, while ordinary metal coatings possess a certain degree of magnetic permeability, it is difficult to achieve a good balance between magnetic permeability and corrosion resistance. Therefore, how to maintain or even improve the magnetic permeability of the magnetic plate assembly while ensuring its corrosion resistance reliability has become a pressing technical problem to be solved in this field. Summary of the Invention

[0004] The main objective of this invention is to provide a magnetic plate assembly, a sound-generating device, and an electronic device, aiming to solve the technical problem of how to improve the magnetic conductivity of the magnetic plate assembly while ensuring its corrosion resistance.

[0005] To achieve the above objectives, embodiments of the present invention provide a magnetic conductive plate assembly, the magnetic conductive plate assembly comprising: a body portion and a plating layer disposed on the surface of the body portion, the main body of the plating layer being a polycrystalline material composed of Ni and Co elements, the polycrystalline material having at least one of a face-centered cubic structure and a close-packed hexagonal crystal structure, the average grain size of the plating layer being 0.01~15 μm, and the self-corrosion potential of the plating layer in a 3.5 wt.% NaCl solution being -0.7~-0.1 V.

[0006] In one embodiment, the average grain size of the coating gradually decreases from the side closer to the body portion to the side farther from the body portion. The coating includes a first region closer to the body portion and a second region farther from the body portion, wherein the average grain size of the first region is 0.1~15 μm and the average grain size of the second region is 0.01~1 μm.

[0007] In one embodiment, the nanoindentation hardness of the coating gradually increases from the side closer to the body portion to the side farther from the body portion, wherein the nanoindentation hardness of the first region is 2~10 GPa and the nanoindentation hardness of the second region is 5~30 GPa.

[0008] In one embodiment, the average thickness of the coating is less than or equal to 20% of the average thickness of the body portion.

[0009] In one embodiment, the average thickness of the body portion is greater than or equal to 0.05 mm.

[0010] In one embodiment, the average thickness of the coating is 1~30 μm.

[0011] In one embodiment, the roughness of the coating is 0.01~0.8 μm.

[0012] In one embodiment, the saturation magnetization of the coating is 200~2000 emu / cm. 3 .

[0013] In one embodiment, the coating is annealed at a temperature of 100~800 °C.

[0014] To achieve the above objectives, embodiments of the present invention provide a sound-generating device, the sound-generating device including a housing and a magnetic circuit structure disposed on the housing, the magnetic circuit structure including a magnet assembly and a magnetic guide plate assembly as described above, the magnetic guide plate assembly including at least one of a magnetic guide yoke and a magnetic guide plate disposed at one end of the magnet assembly away from the magnetic guide yoke.

[0015] To achieve the above objectives, embodiments of the present invention provide an electronic device, which includes the magnetic plate assembly described above, or the sound-generating device described above.

[0016] This invention provides a magnetically conductive plate assembly, comprising: a body portion and a coating disposed on the surface of the body portion. The coating is primarily composed of a polycrystalline material consisting of Ni and Co elements. The polycrystalline material has at least one of a face-centered cubic structure and a close-packed hexagonal crystal structure. The average grain size of the coating is 0.01~15 μm, and the self-corrosion potential of the coating in a 3.5 wt.% NaCl solution is -0.7~-0.1 V. In this embodiment, the coating is primarily composed of a polycrystalline material consisting of Ni (nickel) and Co (cobalt), having at least one of a face-centered cubic structure and a close-packed hexagonal crystal structure. Ni has high permeability, and Co has high saturation magnetic induction. The combination of these two materials gives the coating both high permeability and high saturation magnetic induction, thereby effectively enhancing the magnetic conductivity of the magnetically conductive plate assembly. Simultaneously, the addition of Co helps Ni form a more stable oxide film with fewer defects, significantly improving the corrosion resistance of the coating. In terms of crystal structure, Ni's face-centered cubic structure has many slip systems and is prone to plastic deformation, giving the coating good toughness. When the Co content is low, Co and Ni form a solid solution while still maintaining a face-centered cubic structure. As the Co content increases, some structures transform into a close-packed hexagonal structure. Due to the fewer slip systems and higher strength of the close-packed hexagonal structure, the combination of these two crystal structures gives the coating both excellent magnetic permeability and high strength, effectively resisting deformation and damage under external forces. Furthermore, the average grain size of the coating is controlled within the range of 0.01~15μm, ensuring effective movement of magnetic domains to maintain excellent magnetic permeability, while also improving the density and corrosion resistance of the coating through an appropriate amount of grain boundaries. Based on the synergistic effect of the above grain size and composition, the self-corrosion potential of the coating in 3.5 wt.% NaCl solution is controlled between -0.7 and -0.1 V, exhibiting good corrosion resistance. Therefore, it can effectively prevent the body from oxidizing and forming non-magnetic oxides, avoiding a decrease in magnetic permeability. The embodiments of the present invention improve the corrosion resistance and long-term reliability of the magnetic plate assembly while ensuring good magnetic permeability of the coating, and achieve synergistic optimization of magnetic permeability and corrosion resistance. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the magnetic conductive plate assembly involved in the embodiments of the present invention; Figure 2 This is a schematic diagram of the coating structure involved in the embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the sound-generating device involved in the embodiment of the present invention; Figure 4 The XRD test image is shown in Embodiment 1 of the present invention. Figure 5The above are frequency response curves of Embodiment 1 and Comparative Example 1, which are related to the embodiments of the present invention.

[0018] Explanation of reference numerals in the attached figures 100. Magnetic plate assembly; 101. Body; 102. Plating; 103a, Region 1; 103b, Region 2; 101a, Central magnetic plate; 101b, Side magnetic plate; 101c, Magnetic yoke; 200. Sound-generating device; 201. Housing; 202. Magnetic gap; 203. Diaphragm assembly; 204. Voice coil; 205a, center magnet; 205b, side magnet.

[0019] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0021] Hereinafter, embodiments of the magnetic plate assembly, sound-generating device, and electronic device of the present invention are disclosed in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present invention and are not intended to limit the subject matter of the claims.

[0022] The "range" disclosed in this invention is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0023] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0024] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0025] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments. However, the present invention is not limited to the listed embodiments, but should also include any other known modifications within the scope of the claims of the present invention.

[0026] To better understand the technical solution of the present invention, a detailed description will be provided below in conjunction with the accompanying drawings and specific embodiments.

[0027] This invention provides a magnetic guide plate assembly, with reference to... Figure 1The magnetic plate assembly 100 includes a body portion 101 and a plating layer 102 disposed on the surface of the body portion 101. The main body of the plating layer 102 is a polycrystalline material composed of Ni and Co elements. The polycrystalline material has at least one of a face-centered cubic structure and a close-packed hexagonal crystal structure. The average grain size of the plating layer 102 is 0.01~15μm, and the self-corrosion potential of the plating layer 102 in a 3.5 wt.% NaCl solution is -0.7~-0.1 V.

[0028] Optionally, the plating layer 102 may be disposed on at least one surface of the body portion 101; for example, the plating layer 102 may be disposed on at least one of the upper surface, lower surface and side surface of the body portion 101.

[0029] Optionally, the magnetic plate assembly 100 includes at least one of a magnetic yoke and a magnetic plate.

[0030] Optionally, the body part 101 is a basic structural component in the magnetic plate assembly 100 that plays a role in bearing and guiding magnetism, and it is itself a magnetic guiding component in the magnetic circuit structure.

[0031] It should be noted that the magnetic plate assembly 100 in this embodiment of the invention is a magnetically conductive component applied in the magnetic circuit structure of a sound-generating device (e.g., a loudspeaker) and having the aforementioned plating layer 102 on its surface. The magnetic plate assembly 100 can be understood as an integral component formed by the formation of the plating layer 102 on the surfaces of the magnetic yoke (i.e., the frame) and / or the magnetic plate (i.e., the washer) in the magnetic circuit structure of the sound-generating device. That is, the magnetic plate assembly 100 can be an assembly composed of the magnetic yoke and its surface plating layer 102, or an assembly composed of the magnetic plate and its surface plating layer 102, or both. Therefore, the magnetic plate assembly 100 in this embodiment of the invention is not limited to a single component at a specific location, but generally refers to a magnetically conductive component with the features of the aforementioned plating layer 102 of this invention on its surface. In this embodiment of the invention, the magnetic plate assembly 100 can function as a magnetic yoke, a magnetic plate, or both, depending on the specific design requirements.

[0032] Optionally, the main body of the coating 102 is a polycrystalline material composed of Ni (nickel) and Co (cobalt) elements, and the polycrystalline material has at least one of face-centered cubic structure and close-packed hexagonal crystal structure.

[0033] In this embodiment, Ni has high magnetic permeability and Co has high saturation magnetic induction. The combination of the two gives the coating 102 both high magnetic permeability and high saturation magnetic induction, thereby effectively enhancing the magnetic permeability of the magnetic plate assembly 100. Simultaneously, the addition of Co helps Ni form a more stable oxide film with fewer defects, significantly improving the corrosion resistance of the coating 102. In terms of crystal structure, Ni has a face-centered cubic structure with many slip systems, making it prone to plastic deformation, thus endowing the coating 102 with good toughness. When the Co content is low, Co and Ni form a solid solution while still maintaining a face-centered cubic structure. As the Co content increases, part of the structure transforms into a close-packed hexagonal structure. Due to the low slip system and high strength of the close-packed hexagonal structure, the combination of these two crystal structures gives the coating 102 both excellent magnetic permeability and high strength, effectively resisting deformation and damage under external forces.

[0034] Optionally, the average grain size of the coating 102 is 0.01~15 μm; for example, the average grain size of the coating 102 is 0.01 μm, 0.05 μm, 0.1 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 3 μm, 5 μm, 7 μm, 10 μm, 12 μm, 14 μm, 15 μm, etc.

[0035] In this embodiment, when the grain size of the coating 102 is less than 0.01 μm, the coating 102 is at the nanocrystalline level. While the coating 102 exhibits extremely high hardness, the excessively small grain size and excessive crystallization negatively impact the movement of magnetic domains, leading to a sharp decrease in magnetic permeability. Conversely, when the grain size is too large, the reduced grain boundaries make it easier for corrosive media to corrode along these boundaries, reaching the body 101. Therefore, this embodiment of the invention controls the average grain size of the coating within the range of 0.01~15 μm, ensuring effective movement of magnetic domains to maintain excellent magnetic permeability while simultaneously improving the density and corrosion resistance of the coating through an appropriate number of grain boundaries.

[0036] Optionally, the self-corrosion potential of coating 102 in 3.5 wt.% NaCl solution is -0.7 to -0.1 V. For example, the self-corrosion potential of coating 102 in 3.5 wt.% NaCl solution is -0.7 V, -0.5 V, -0.3 V, -0.1 V, etc.

[0037] Optionally, the self-corrosion potential represents the corrosion tendency of a material in a 3.5 wt.% NaCl solution. The more positive the potential, the less likely the material is to lose electrons, and the better its corrosion resistance.

[0038] Optionally, the self-corrosion potential can be obtained using a Tafel curve; for example, using a three-electrode system in an electrochemical analyzer, with a platinum sheet as the auxiliary electrode, a saturated calomel electrode as the reference electrode, the sample as the working electrode, and a 3.5 wt.% NaCl solution as the test solution. Since the electrode potential of the reference electrode is known, the electrode potential of the electrode under test can be calculated, and then the relationship curve between the current and the electrode potential, i.e., the polarization curve, can be obtained. The self-corrosion potential can then be calculated using the Tafel extrapolation method.

[0039] It is understandable that when the self-corrosion potential is below -0.7 V, the corrosion resistance of the coating 102 is poor and it is difficult to protect the body 101. However, in this embodiment of the invention, based on the synergistic effect of the above-mentioned grain size and composition, the self-corrosion potential of the coating 102 in 3.5 wt.% NaCl solution is controlled between -0.7 and -0.1 V, which has good corrosion resistance. Therefore, it can effectively prevent the body 101 from oxidizing and forming non-magnetic oxides, and avoid the decline in magnetic permeability.

[0040] Optionally, compared to amorphous materials, the polycrystalline structure used in this embodiment of the invention has a high atomic packing density and a high mass percentage of ferromagnetic materials (Ni, Co). In the coating 102, the mass percentage of Ni and Co can be controlled to be above 90 wt.%, while conventional amorphous materials generally have less than 80 wt.% of ferromagnetic elements. The higher the proportion of ferromagnetic elements, the more atomic magnetic moments are contained in the coating 102, the stronger the interatomic interactions, and the better the magnetic permeability. Simultaneously, the polycrystalline structure has perfect crystallization and stable structure, which can avoid the fluctuations in magnetic permeability caused by uncontrollable crystallization transformations due to stress or temperature changes during the use of amorphous materials, ensuring stable and consistent magnetic performance over long-term use.

[0041] In this embodiment, the main body of the coating 102 is a polycrystalline material composed of Ni (nickel) and Co (cobalt), possessing at least one of a face-centered cubic (FCC) structure and a close-packed hexagonal crystal structure. Ni has high magnetic permeability, and Co has high saturation magnetic induction. The combination of these two elements gives the coating 102 both high magnetic permeability and high saturation magnetic induction, effectively enhancing the magnetic permeability of the magnetic plate assembly 100. Simultaneously, the addition of Co helps Ni form a more stable oxide film with fewer defects, significantly improving the corrosion resistance of the coating 102. Regarding the crystal structure, Ni's face-centered cubic structure has many slip systems and is prone to plastic deformation, giving the coating 102 good toughness. When the Co content is low, Co and Ni form a solid solution while maintaining a face-centered cubic structure. As the Co content increases, part of the structure transforms into a close-packed hexagonal structure. Due to the fewer slip systems and higher strength of the close-packed hexagonal structure, the combination of these two crystal structures allows the coating 102 to possess both excellent magnetic permeability and high strength, effectively resisting deformation and damage under external forces. Furthermore, the average grain size of the coating 102 is controlled within the range of 0.01~15μm, which ensures effective movement of magnetic domains to maintain excellent magnetic permeability, while also improving the density and corrosion resistance of the coating 102 through an appropriate amount of grain boundaries. Based on the synergistic effect of the above-mentioned grain size and composition, the self-corrosion potential of the coating 102 in 3.5 wt.% NaCl solution is controlled between -0.7 and -0.1 V, exhibiting good corrosion resistance. Therefore, it can effectively prevent the body 101 from oxidizing and forming non-magnetic oxides, avoiding a decrease in magnetic permeability. This embodiment of the invention improves the corrosion resistance and long-term reliability of the magnetic plate assembly 100 while ensuring good magnetic permeability of the coating 102, achieving synergistic optimization of magnetic permeability and corrosion resistance.

[0042] In one feasible implementation, refer to Figure 2 The average grain size of the coating 102 gradually decreases from the side closer to the body portion 101 to the side farther away from the body portion 101. The coating 102 includes a first region 103a on the side closer to the body portion 101 and a second region 103b on the side farther away from the body portion 101. The average grain size of the first region 103a is 0.1~15 μm, and the average grain size of the second region 103b is 0.01~1 μm.

[0043] Optionally, the average grain size of the first region 103a is 0.1 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, etc.

[0044] Optionally, the average grain size of the second region 103b is 0.01 μm, 0.02 μm, 0.04 μm, 0.06 μm, 0.08 μm, 0.09 μm, 0.1 μm, 0.2 μm, 0.4 μm, 0.6 μm, 0.8 μm, 1 μm, etc.

[0045] In this embodiment, the average grain size of the coating 102 exhibits a gradient distribution, gradually decreasing from the side closer to the body portion 101 to the side farther away from the body portion 101. A first region 103a is provided on the side of the coating 102 closer to the body portion 101, with an average grain size of 0.1~15 μm, while a second region 103b is provided on the side farther away from the body portion 101, with an average grain size of 0.01~1 μm. The grain size of the body portion 101 is generally on the order of tens of micrometers. Therefore, maintaining a coarser grain size in the coating 102 near the body portion 101 can reduce the lattice difference between the body portion 101 and the coating 102, thereby reducing internal stress and improving adhesion. On the other hand, larger grain sizes result in fewer grain boundaries, lower magnetic reluctance, and better magnetic permeability. Therefore, the similar grain size of the coating 102 near the body portion 101 provides a transition channel for the passage of magnetic field lines, avoiding abrupt changes in magnetic reluctance due to excessively small grain sizes. The outer surface of the coating 102, which is far from the main body 101 (i.e., the second region 103b), is provided with micro- and nano-particles, which greatly increases the grain boundary volume fraction. The fine-grained structure can effectively block corrosive media such as chloride ions from penetrating into the interior along the vertical grain boundaries, thereby improving corrosion resistance. At the same time, the gradient distribution can avoid abrupt changes in grain size, which could lead to stress concentration and microcracks.

[0046] In one feasible embodiment, the nanoindentation hardness of the coating 102 gradually increases from the side closer to the body portion 101 to the side farther away from the body portion 101, wherein the nanoindentation hardness of the first region 103a is 2~10 GPa and the nanoindentation hardness of the second region 103b is 5~30 GPa.

[0047] Optionally, the nanoindentation hardness of the first region 103a is 2 GPa, 3 GPa, 4 GPa, 5 GPa, 6 GPa, 7 GPa, 8 GPa, 9 GPa, 10 GPa, etc.

[0048] Optionally, the nanoindentation hardness of the second region 103b is 5 GPa, 8 GPa, 10 GPa, 13 GPa, 15 GPa, 17 GPa, 20 GPa, 22 GPa, 25 GPa, 28 GPa, 30 GPa, etc.

[0049] In this embodiment, the grain size of the coating 102 exhibits a gradient distribution, meaning that the grain size gradually decreases from the side closer to the body portion 101 to the side farther away from the body portion 101, and correspondingly, the number of grain boundaries gradually increases. Grain boundaries hinder the movement of dislocations. The finer the grains and the more grain boundaries there are, the greater the resistance to dislocation movement, thus requiring a greater external force to activate dislocations, which macroscopically manifests as an increase in material hardness. Therefore, the hardness of the coating 102 also exhibits a gradient distribution, gradually increasing from the side closer to the body portion 101 to the side farther away from the body portion 101. Nanoindentation testing revealed that the hardness of the coating 102 (i.e., the first region 103a) near the body 101 ranges from 2 to 10 GPa. This region has a larger grain size and lower hardness, similar to the hardness of the body 101, resulting in low internal stress and good adhesion between the coating and the body 101. Conversely, the hardness of the coating 102 (i.e., the second region 103b) away from the body 101 ranges from 5 to 30 GPa. This region has a smaller grain size and higher hardness, providing the coating with resistance to deformation and preventing wear during manufacturing and reliability testing. Through this gradient design, the coating 102 achieves synergistic optimization of high surface hardness and wear resistance while maintaining good adhesion to the body 101.

[0050] In one feasible embodiment, the average thickness of the coating 102 is less than or equal to 20% of the average thickness of the body portion 101; for example, the average thickness of the coating 102 is less than or equal to 20%, 18%, 16%, 15%, 14%, 12%, 10%, 8%, 6%, 5%, etc. of the average thickness of the body portion 101.

[0051] In one feasible embodiment, the average thickness of the body portion 101 is greater than or equal to 0.05 mm.

[0052] In one feasible embodiment, the average thickness of the coating 102 is 1 to 30 μm; for example, the average thickness of the coating 102 is 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, etc.

[0053] Optionally, the average thickness of the coating 102 is 1~20 μm.

[0054] In this embodiment, if the thickness of the body portion 101 is too thin, the body portion 101 is prone to deformation due to heat and mechanical stirring during the fabrication of the plating layer 102. Therefore, in this embodiment, the average thickness of the body portion 101 is determined to be greater than or equal to 0.05 mm. Furthermore, since the plating layer 102 in this embodiment is a nickel-cobalt alloy plating layer, its hardness is much higher than that of the body portion 101. If the thickness of the plating layer 102 is too large, the internal stress will be too high, and the plating layer 102 will be prone to microcracks. Therefore, its thickness percentage should not be too large (i.e., less than or equal to 20% of the average thickness of the body portion 101). In addition, the thicker the plating layer 102, the larger the gap between the magnet assembly and the magnetic guide plate assembly 100, resulting in poorer magnetic permeability. Therefore, in this embodiment, the thickness of the plating layer is less than or equal to 30 μm. Moreover, the grain size of the second region 103b of the plating layer 102 is small, exhibiting excellent corrosion resistance. Therefore, a relatively thin thickness can achieve the anti-corrosion effect. Thus, in this embodiment, the thickness of the plating layer is greater than or equal to 1 μm.

[0055] In one feasible embodiment, the roughness of the coating 102 is 0.01~0.8 μm; for example, the roughness of the coating 102 is 0.01 μm, 0.05 μm, 0.1 μm, 0.15 μm, 0.2 μm, 0.25 μm, 0.3 μm, 0.35 μm, 0.4 μm, 0.45 μm, 0.5 μm, 0.55 μm, 0.6 μm, 0.65 μm, 0.7 μm, 0.75 μm, 0.8 μm, etc.

[0056] Optionally, the roughness of the coating 102 is 0.05~0.3 μm.

[0057] Optionally, the coating 102 is a nickel-cobalt alloy coating. Since the Co element has the effect of grain refinement, the coating 102 has a smaller surface roughness.

[0058] In this embodiment, the grain size of the coating 102 surface (i.e., the second region 103b) is small, the surface grain orientation is dispersed, the distribution is uniform, and the undulations are small, thus having a low roughness. However, the roughness of the coating 102 should not be too low, because excessively low roughness is not conducive to the adhesion of the adhesive. Therefore, in this embodiment of the invention, the roughness of the coating 102 is determined to be 0.01~0.8μm.

[0059] In one feasible embodiment, the saturation magnetization of the coating 102 is 200~2000 emu / cm. 3 For example, the saturation magnetization of coating 102 is 200 emu / cm. 3 300 emu / cm 3 500 emu / cm 3 800 emu / cm3 1000 emu / cm 3 1200 emu / cm 3 1500 emu / cm 3 1800 emu / cm 3 2000 emu / cm 3 wait.

[0060] Optionally, saturation magnetization refers to the magnetization intensity of a material when it is magnetized to its maximum extent in an applied magnetic field, i.e., when all magnetic moments are aligned in the same direction. For coating 102, when its saturation magnetization is less than 200 emu / cm 3 At this time, the magnetism is weak and the magnetic permeability is poor. However, the higher the saturation magnetization, the higher the cobalt content in the coating 102, resulting in poorer corrosion resistance and increased cost. Therefore, in this embodiment of the invention, the saturation magnetization of the coating 102 is determined to be 200~2000 emu / cm. 3 To achieve a balance between various performance characteristics.

[0061] In one feasible embodiment, the coating 102 is annealed at a temperature of 100~800°C. For example, the annealing temperature is 100°C, 200°C, 300°C, 400°C, 500°C, 600°C, 700°C, 800°C, etc.

[0062] In this embodiment, annealing is used to allow the atoms of the coating 102 to diffuse and rearrange, thereby eliminating internal stress and removing vacancies and defects. However, when the annealing temperature is too high, the grains grow excessively, making it difficult to maintain the fine grains on the surface of the coating 102. Conversely, when the annealing temperature is too low, the atomic mobility is insufficient, resulting in no significant effect. Therefore, this embodiment of the invention determines the annealing temperature to be between 100 and 800 °C.

[0063] This invention also provides a sound-generating device, which includes a housing and a magnetic circuit structure disposed on the housing. The magnetic circuit structure includes a magnet assembly and a magnetic guide plate assembly as described above. The magnetic guide plate assembly includes at least one of a magnetic guide yoke and a magnetic guide plate disposed at the end of the magnet assembly away from the magnetic guide yoke.

[0064] Optionally, refer to Figure 3The sound-generating device 200 includes a housing 201 and a magnetic circuit structure disposed on the housing 201. The magnetic circuit structure may include a central magnetic part and a side magnetic part, wherein the central magnetic part and the side magnetic part are spaced apart to form a magnetic gap 202. The sound-generating device 200 also includes a diaphragm assembly 203 and a voice coil 204. One end of the voice coil 204 is connected to the diaphragm assembly 203, and the other end of the voice coil 204 is inserted into the magnetic gap 202, so that when energized, it is driven by the magnetic field to vibrate and generate sound. The central magnetic part includes a central magnet 205a and a central magnetic guide plate 101a, and the side magnetic part includes a side magnet 205b and a side magnetic guide plate 101b. The central magnet 205a and the side magnet 205b together form a magnet assembly to provide magnetic flux to the magnetic circuit. One end of the central magnet 205a is connected to the magnetic yoke 101c, and the other end is connected to the central magnetic plate 101a; one end of the side magnet 205b is connected to the magnetic yoke 101c, and the other end is connected to the side magnetic plate 101b. With this arrangement, the magnetic flux forms a closed loop via the magnetic yoke 101c, the central magnet 205a, the central magnetic plate 101a, the magnetic gap 202, the side magnetic plate 101b, and the side magnet 205b, resulting in a high-intensity magnetic field within the magnetic gap 202, thereby enhancing the driving force of the voice coil 204 and the sensitivity of the sound-generating device 200.

[0065] Optionally, refer to Figure 3 The surfaces of the central magnetic plate 101a, the side magnetic plates 101b, and the magnetic yoke 101c are provided with the coating 102 as described above, thereby achieving synergistic optimization of magnetic conductivity and corrosion resistance.

[0066] Compared with conventional technology, the beneficial effects of the sound-generating device provided in the embodiments of the present invention are the same as those of the magnetic plate assembly provided in the above embodiments, and other technical features in the sound-generating device are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.

[0067] This invention also provides an electronic device, including the magnetic plate assembly or sound-generating device described above.

[0068] In this embodiment, electronic devices include mobile phones, laptops, tablets, VR (Virtual Reality) devices, AR (Augmented Reality) devices, TWS (True Wireless Stereo) earphones, smart speakers, smart wearable devices, etc.

[0069] Compared with conventional technology, the beneficial effects of the electronic device provided in the embodiments of the present invention are the same as those of the magnetic conductive plate assembly provided in the above embodiments, and other technical features of the electronic device are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.

[0070] To ensure that the details and operations of the above embodiments of the present invention can be clearly understood by those skilled in the art, and to demonstrate the significant advancements in the performance of the embodiments of the present invention, the following examples illustrate the above technical solutions. It should be noted that the following descriptions are merely exemplary and not intended to limit the specific scope of the present invention.

[0071] Example 1 An electroplating solution is provided, wherein the components of the electroplating solution include: 200 g / L nickel sulfate, 30 g / L cobalt sulfate, 50 g / L boric acid, and 15 g / L nickel chloride. Based on the above electroplating solution, a nickel-cobalt alloy coating is electroplated on the surface of the body portion of an SPCC substrate, wherein the electroplating current density exhibits a gradient distribution, with an initial current density of 1 A / dm³. 2 The temperature was 55℃; then the current density was gradually increased to 5A / dm. 2 The coating is formed at 40℃; the coated product is then cleaned and subjected to vacuum annealing at 300℃ for 1 hour, followed by furnace cooling to room temperature to obtain a magnetic plate.

[0072] Comparative Example 1 An electroplating solution is provided, wherein the components of the electroplating solution include: 200 g / L nickel sulfate, 30 g / L cobalt sulfate, 50 g / L boric acid, and 15 g / L nickel chloride. Based on the above electroplating solution, a nickel-cobalt alloy coating is electroplated on the surface of the body portion of an SPCC substrate, wherein the electroplating current density is 3 A / dm³. 2 At a temperature of 45℃, a coating is formed, resulting in a magnetic plate.

[0073] After polishing the cross-sections of the coatings in Example 1 and Comparative Example 1, they were etched with an etchant, and the grain size of the coatings was measured using a scanning electron microscope. The etchant solution contained concentrated hydrochloric acid, concentrated nitric acid, and water in a ratio of 1:1:1. The test results showed that in Example 1, the average grain size in the first region of the coating near the body was 3-5 μm, while the average grain size in the second region of the coating away from the body was 0.2 μm. This is because during the electroplating process, the initial current density was low and the temperature was high, which effectively reduced the nucleation rate and allowed the grains to grow sufficiently, thus controlling the grain size of the first region of the coating to be 3-5 μm. As the current density increased, the nucleation rate exceeded the growth rate, resulting in a decrease in the average grain size, leading to an average grain size of 0.2 μm in the second region of the coating. In Comparative Example 1, the current density and temperature remained constant, resulting in a consistent grain size with an average grain size of 3 μm.

[0074] Furthermore, the coating of Example 1 was subjected to XRD (X-ray diffraction) testing, and the results were as follows: Figure 4 ,visible Figure 4The test spectrum showed obvious (111) and (200) diffraction peaks, which indicates that the coating of Example 1 has a face-centered cubic crystal structure.

[0075] Furthermore, the hardness of the coatings in Example 1 and Comparative Example 1 was tested using nanoindentation. In Example 1, the nanoindentation hardness of the coating near the body (i.e., the first region) was 5 GPa, while the nanoindentation hardness of the coating away from the body (i.e., the second region) was 23 GPa. This shows that the nanoindentation hardness of the coatings in Example 1 exhibits a gradient distribution. This is because the grain size of the coatings in Example 1 exhibits a gradient distribution; that is, the grain size gradually decreases from the side near the body to the side away from the body. The finer the grains, the more grain boundaries there are, and the greater the resistance to dislocation movement. Therefore, a larger external force is required to initiate dislocation movement, which macroscopically manifests as an increase in material hardness. Thus, the hardness of the coatings in Example 1 also exhibits a gradient distribution, gradually increasing from the side near the body to the side away from the body. In contrast, the grain size of the coatings in Comparative Example 1 is basically uniform, therefore their nanoindentation hardness is also basically uniform, both being 17 GPa.

[0076] Furthermore, the polarization curves of the magnetic plates in Example 1 and Comparative Example 1 in 3.5 wt.% NaCl solution were tested using an electrochemical testing station. The results showed that the self-corrosion potential of Example 1 was -0.28 V, indicating good corrosion resistance, while the self-corrosion potential of Comparative Example 1 was -0.47 V, significantly lower than that of Example 1, indicating poor corrosion resistance. This is because the grain size on the side of the coating away from the main body (i.e., the second region) in Example 1 is smaller, resulting in a sharp increase in the grain boundary volume fraction. The fine-grained structure effectively blocks corrosive media such as chloride ions from penetrating inward along the vertical grain boundaries, thus improving corrosion resistance.

[0077] Furthermore, the roughness of the coatings in Example 1 and Comparative Example 1 was tested using the contact method. The roughness Ra value of Example 1 was 0.16 μm, and that of Comparative Example 1 was 0.3 μm. This is because the grain size of the coating surface (i.e., the second region) in Example 1 is finer, the surface grain orientation is dispersed, uniformly distributed, and the undulations are small, thus resulting in lower roughness.

[0078] Furthermore, the saturation magnetization of the coating in Example 1 was measured to be 390 emu / cm using a VSM (vibrating sample magnetometer). 3 The saturation magnetization of the coating in Comparative Example 1 is 380 emu / cm. 3 It is evident that controlling the average grain size of the coating to exhibit a gradient distribution can also enhance its saturation magnetization.

[0079] Furthermore, the magnetic plates from Example 1 and Comparative Example 1 were assembled into the same loudspeaker, and the loudspeaker unit was placed in an environment of 65°C and 95%RH. After 568 hours, Comparative Example 1 showed significant corrosion, while Example 1 showed no significant change. This is mainly because the coating surface of Example 1 has a small grain size, many grain boundaries, and a higher corrosion resistance potential, thus exhibiting better corrosion resistance.

[0080] Furthermore, the acoustic performance of the loudspeakers prepared in Example 1 and Comparative Example 1 was tested before and after high-temperature and high-humidity storage. The results of their frequency response curves (FR curves) are as follows: Figure 5 As shown. According to Figure 5 It can be seen that the acoustic performance of Example 1 and Comparative Example 1 before the test was similar, but that of Comparative Example 1 was slightly lower. However, after high temperature and high humidity storage, the performance of Comparative Example 1 decreased significantly, while that of Example 1 showed no significant change. This indicates that Example 1 has better corrosion resistance. After high temperature and high humidity storage, the magnetic plate did not corrode, and the magnetic permeability did not change significantly, so the acoustic curves were basically the same. In contrast, the magnetic plate of Comparative Example 1 corroded after high temperature and high humidity storage, producing non-magnetic Fe2O3, which damaged the magnetic permeability path, reduced the magnetic permeability, decreased the driving force of the voice coil, and significantly reduced the sensitivity of the loudspeaker.

[0081] In summary, the embodiments of the present invention can improve the corrosion resistance and long-term reliability of the magnetic plate assembly while ensuring good magnetic permeability of the coating, thus achieving synergistic optimization of magnetic permeability and corrosion resistance.

[0082] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the patent protection scope of the present invention.

Claims

1. A magnetic shunt assembly, characterized by, The magnetic conductive plate assembly includes: a body and a coating disposed on the surface of the body. The main body of the coating is a polycrystalline material composed of Ni and Co elements. The polycrystalline material has at least one of a face-centered cubic structure and a close-packed hexagonal crystal structure. The average grain size of the coating is 0.01~15 μm. The self-corrosion potential of the coating in 3.5 wt.% NaCl solution is -0.7~-0.1 V.

2. The magnetic flux guide plate assembly of claim 1, wherein, The average grain size of the coating gradually decreases from the side closer to the body portion to the side farther away from the body portion. The coating includes a first region closer to the body portion and a second region farther away from the body portion, wherein the average grain size of the first region is 0.1~15 μm and the average grain size of the second region is 0.01~1 μm.

3. The magnetic flux guide plate assembly of claim 2, wherein, The nanoindentation hardness of the coating gradually increases from the side closer to the body portion to the side farther away from the body portion, wherein the nanoindentation hardness of the first region is 2~10 GPa and the nanoindentation hardness of the second region is 5~30 GPa.

4. The magnetic conductive plate assembly as claimed in claim 1, characterized in that, The average thickness of the coating is less than or equal to 20% of the average thickness of the body portion; And / or, the average thickness of the body portion is greater than or equal to 0.05 mm.

5. The magnetic conductive plate assembly as claimed in claim 1, characterized in that, The average thickness of the coating is 1~30 μm.

6. The magnetic plate assembly as claimed in claim 1, characterized in that, The roughness of the coating is 0.01~0.8 μm.

7. The magnetic plate assembly as claimed in claim 1, characterized in that, The saturation magnetization of the plating layer is 200-2000 emu / cm 3 .

8. The magnetic plate assembly as claimed in claim 1, characterized in that, The coating is annealed at a temperature of 100~800 ℃.

9. A sound-generating device, characterized in that, The sound-generating device includes a housing and a magnetic circuit structure disposed on the housing. The magnetic circuit structure includes a magnet assembly and a magnetic guide plate assembly as described in any one of claims 1 to 8. The magnetic guide plate assembly includes at least one of a magnetic guide yoke and a magnetic guide plate disposed at one end of the magnet assembly away from the magnetic guide yoke.

10. An electronic device, characterized in that, The electronic device includes a magnetic plate assembly as described in any one of claims 1 to 8, or a sound-generating device as described in claim 9.

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