A diaphragm and a method for preparing the same

Abstract

The diaphragm involved in the present invention includes an intermediate layer and a coating coated on both surfaces of the intermediate layer. The intermediate layer is a carbon graphite / carbon nanotube layer, and the coating is a diamond-like coating. The carbon nanotubes are interwoven to form a porous membrane with a macroscopic membrane-like morphology and a microscopic network structure. The carbon graphite is interspersed in the internal gaps of the carbon nanotube porous membrane. The carbon graphite and carbon nanotubes together form a carbon graphite / carbon nanotube layer with a relatively dense internal structure. The diamond-like coating has high specific elasticity, high bending rigidity and high internal damping. The obtained diaphragm has good acoustic effect, good moisture-proof performance, good mildew resistance, low production cost and simple preparation method.

Description

Technical Field

[0001] The invention relates to a diaphragm and a preparation method thereof. Background Art

[0002] With the continuous improvement of people's living standards and technological advancements, digital audio technology has developed rapidly, and the demand for speaker sound quality is also becoming increasingly higher. The diaphragm is one of the most important components of a speaker's sound production. The reciprocating vibration of the diaphragm causes the surrounding air medium to form a density wave, which causes the eardrum to vibrate, thus allowing the human ear to perceive sound. Therefore, the physical properties of the diaphragm material itself have a decisive influence on the sound quality. From the perspective of acoustic effect, that is, the steady-state vibration, there are three requirements for the physical properties of the diaphragm material: 1. To achieve the widest possible playback frequency band, the diaphragm material must have a high specific elastic modulus; 2. To prevent sound distortion and suppress the diaphragm's split vibration during operation, the diaphragm material must have high flexural rigidity; 3. To further improve the speaker's sound quality and smooth the diaphragm's frequency response curve, the diaphragm material must have appropriate internal damping (internal damping can be characterized by the loss factor). Furthermore, from the perspective of operating life, to ensure long-term stable operation, the diaphragm material must also have good moisture and mildew resistance. Research on existing materials has revealed that the use of carbonaceous materials as speaker diaphragms holds great promise, but also presents numerous technical bottlenecks. Compared to common paper-based diaphragm materials, diamond possesses a high specific elastic modulus and flexural rigidity. However, this material exhibits very low internal damping, and is expensive and has high manufacturing costs. Furthermore, diamond film preparation requires a substrate, and after fabrication, the film and substrate often bond tightly, making it difficult to peel from the substrate surface. While carbon graphite has a lower specific elastic modulus than diamond, it exhibits higher internal damping and is inexpensive, making it an ideal diaphragm material. However, carbon graphite exhibits poor film-forming properties and is difficult to form independently. Diamond-like carbon (DLC) exhibits a specific elastic modulus, flexural rigidity, and internal damping that lie between those of diamond and carbon graphite, offering low production costs and excellent film-forming properties. However, DLC film preparation also requires a substrate, and similarly suffers from the problem of tight bonding between the film and substrate, making it difficult to peel from the substrate. Considering both acoustic effects and economic costs, carbon graphite and diamond-like carbon are more suitable for actual diaphragm production. The technical challenge they face is mainly how to make them into an independent and stable carbon membrane body. Summary of the Invention

[0003] The object of the present invention is to provide a diaphragm with good acoustic effect, good moisture resistance, good mildew resistance, low production cost and simple preparation method.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a diaphragm comprising an intermediate layer and a coating applied on both surfaces of the intermediate layer, wherein the intermediate layer is a carbon graphite / carbon nanotube layer and the coating is a diamond-like coating.

[0005] Furthermore, the thickness of the diaphragm is 54 μm-216 μm.

[0006] Furthermore, the carbon graphite / carbon nanotube layer includes carbon graphite and carbon nanotubes, the carbon nanotubes are interwoven, the carbon graphite exists in the gaps between the interwoven carbon nanotubes, and the thickness of the carbon graphite / carbon nanotube layer is 50 μm-200 μm.

[0007] Furthermore, the thickness of the diamond-like carbon coating is 2 μm-8 μm.

[0008] The present invention also provides a method for preparing the diaphragm, and the method is as follows:

[0009] S1, preparing a carbon graphite / carbon nanotube layer, wherein the thickness of the carbon graphite / carbon nanotube layer is 50 μm-200 μm;

[0010] S2. Depositing a diamond-like coating on both surfaces of the carbon graphite / carbon nanotube layer, wherein the thickness of the diamond-like coating is 2 μm-8 μm.

[0011] Furthermore, the carbon graphite / carbon nanotube layer is prepared by a high-temperature carbonization-in-situ growth method.

[0012] Furthermore, the diamond-like coating is prepared by a high-energy pulse magnetron sputtering method.

[0013] Furthermore, the conditions of the high-energy pulse magnetron sputtering are: power supply current is 1A-8A, power supply duty cycle is 40%-80%, power supply frequency is 40kHz-100kHz, pulse negative bias is 200V-1000V, pulse negative bias duty cycle is 30%-60%, and sputtering time is 0.5h-5h.

[0014] The beneficial effects of the present invention are: the diaphragm obtained by the present invention includes a carbon graphite / carbon nanotube layer and a diamond-like coating, the carbon nanotubes are interwoven to form a porous membrane with a macroscopic film-like morphology and a microscopic network structure, the carbon graphite is interspersed in the internal gaps of the carbon nanotube porous membrane, the carbon graphite and carbon nanotubes together form a carbon graphite / carbon nanotube layer with a relatively dense internal structure, and a diamond-like coating with high specific elasticity, high bending rigidity and high internal damping is deposited on its surface, thereby obtaining a diaphragm with excellent comprehensive performance, the diaphragm has good acoustic effects, good moisture-proof performance, good mildew resistance, low production cost and simple preparation method.

[0015] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the structure of the diaphragm shown in the present invention. DETAILED DESCRIPTION

[0017] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0018] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the mechanisms or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0019] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0020] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0021] See Figure 1The diaphragm 1 shown in the present invention includes an intermediate layer 11 and a coating 12 coated on both surfaces of the intermediate layer. The intermediate layer 11 is a carbon graphite / carbon nanotube layer 11, and the coating is a diamond-like coating 12. The carbon graphite / carbon nanotube layer includes carbon graphite 111 and carbon nanotubes 112. The carbon nanotubes 112 are interwoven, and the carbon graphite 111 exists in the gaps between the interwoven carbon nanotubes 112. The thickness of the diaphragm 1 is 54μm-216μm, the thickness of the carbon graphite / carbon nanotube layer 11 is 50μm-200μm, and the thickness of the diamond-like coating 12 is 2μm-8μm.

[0022] Carbon nanotubes (CNTs) are nanotube-like materials formed by the curling of single or multiple layers of graphitic carbon molecules. They are an important class of one-dimensional nanomaterials. High aspect ratio CNTs interweave to form a porous membrane with a macroscopic, film-like morphology and a microscopic, spatial network structure. The CNT porous membrane can serve as a carrier for other materials that are difficult to form into membranes. Carbon graphite, which is difficult to form into membranes, is interspersed within the internal gaps of the CNT porous membrane. Together, the carbon graphite and CNTs form a relatively dense internal structure of a carbon graphite / CNT layer, and a diamond-like coating is deposited on its surface. By rationally controlling the combined morphology of carbon graphite, CNTs, and DLC, a diaphragm with excellent overall performance can be obtained. The diaphragm is made of carbon and contains no organic matter, making it less susceptible to mildew. Furthermore, the DLC coating on the surface is highly hydrophobic, giving the diaphragm excellent moisture resistance.

[0023] The present invention also provides a method for preparing the above-mentioned diaphragm, and the preparation method is as follows:

[0024] S1. Preparation of carbon graphite / carbon nanotube layer by high temperature carbonization-in situ growth method. Specifically,

[0025] a. Polishing a base metal surface of a certain specification to make it smooth and flat, placing it in dilute acid for pickling and etching to roughen the surface, and then ultrasonically cleaning it in deionized water, anhydrous ethanol, and acetone, respectively, and vacuum drying it for use. The base metal can be pure cobalt, pure nickel, or a nickel-cobalt alloy with any element ratio, and there is no restriction on the size of the base metal.

[0026] b 0.5-5 parts of melamine and 0.2-2 parts of sucrose dissolved in 50 parts of glycerol, used to prepare the spray solution, set aside;

[0027] c. Spray the coating liquid onto the pre-treated base metal surface, and then vacuum dry it to allow melamine and sucrose to precipitate and adhere to the base metal surface. The total mass of melamine and sucrose precipitated and adhered to the base metal surface is 300 mg / cm 2 -800mg / cm 2 ;

[0028] d. The base metal with melamine and sucrose deposited on the surface is placed in an atmosphere furnace for heat treatment. The heat treatment atmosphere is an inert atmosphere. The heat treatment temperature is 700°C-1100°C and the heat treatment time is 3h-8h. The melamine and sucrose are cracked into carbon graphite at high temperature. At the same time, carbon nanotubes are grown in situ under the catalytic action of the base metal. The inert atmosphere is pure argon or pure nitrogen. The heat treatment is heated by electromagnetic induction heating.

[0029] e. After the heat treatment is completed and the substrate is cooled to room temperature, the black film layer on the surface of the base metal is directly peeled off to obtain a carbon graphite / carbon nanotube layer having a thickness of 50 μm-200 μm.

[0030] S2. Depositing diamond-like coatings on both surfaces of carbon graphite / carbon nanotube layers using a high-energy pulsed magnetron sputtering method. Specifically,

[0031] g. The obtained carbon graphite / carbon nanotube layer was clamped on the sample stage surface of the magnetron sputtering instrument and vacuumed to 1.0×10 -3 Vacuum degree above Pa;

[0032] h. Argon gas is introduced at a flow rate of 40 sccm-800 sccm, followed by acetylene gas, at a flow rate of 10 sccm-50 sccm, and the vacuum is set to 1Pa-2Pa;

[0033] i. The distance between the sample stage and the magnetron sputtering target is 12cm-18cm, and the sample stage rotation speed is 3r / min-8r / min;

[0034] j. Turn on the sputtering power supply to implement sputtering, the power supply current is 1A-8A, the power duty cycle is 40%-80%, the power frequency is 40kHz-100kHz, the pulsed negative bias is 200V-1000V, the pulsed negative bias duty cycle is 30%-60%, the sputtering time is 0.5h-5h to obtain a diamond-like coating, the thickness of the diamond-like coating is 2μm-8μm;

[0035] k. Repeat the above process to deposit the same diamond-like coating on the other side of the carbon graphite / carbon nanotube layer. The thickness of the diamond-like coating is 2 μm-8 μm, and a diaphragm with a thickness of 54 μm-216 μm is obtained.

[0036] The following describes the method for preparing the diaphragm with reference to a specific embodiment.

[0037] Example 1

[0038] S1. Preparation of carbon graphite / carbon nanotube layer by high temperature carbonization-in situ growth method. Specifically,

[0039] a. Polish the surface of a 20mm×10mm×0.1mm pure metal cobalt sheet with metallographic sandpaper to make it smooth and flat, place it in 5% dilute hydrochloric acid for pickling and etching to roughen the surface, and then ultrasonically clean it in deionized water, anhydrous ethanol and acetone respectively, vacuum dry it and set aside.

[0040] b. Dissolve 2 parts of melamine and 1 part of sucrose in 50 parts of glycerol to prepare the spray solution and set aside;

[0041] c. Spray the coating liquid onto the surface of the pre-treated pure metal cobalt sheet, and then vacuum dry it to allow melamine and sucrose to precipitate and adhere to the surface of the base metal. The total mass of melamine and sucrose precipitated and adhered to the surface of the base metal is 350 mg / cm 2 ;

[0042] d. The pure metal cobalt sheet with melamine and sucrose deposited on the surface was placed in an atmosphere furnace for heating. The heat treatment atmosphere was pure argon, the heat treatment temperature was 700 ° C, the heat treatment time was 3h, and the heat treatment was heated by electromagnetic induction heating;

[0043] e. After the heat treatment is completed and the substrate is cooled to room temperature, the black film layer on the surface of the base metal is directly peeled off to obtain the carbon graphite / carbon nanotube layer.

[0044] S2. Depositing diamond-like coatings on both surfaces of carbon graphite / carbon nanotube layers using a high-energy pulsed magnetron sputtering method. Specifically,

[0045] g. The obtained carbon graphite / carbon nanotube layer was clamped on the sample stage surface of the magnetron sputtering instrument and vacuumed to 1.0×10 -3 Vacuum degree above Pa;

[0046] h. Argon gas was introduced at a flow rate of 100 sccm, followed by acetylene gas at a flow rate of 20 sccm, and the vacuum was set to 1.5 Pa;

[0047] i. The distance between the sample stage and the magnetron sputtering target is 12 cm, and the sample stage rotation speed is 3 r / min;

[0048] j. Turn on the sputtering power supply to implement sputtering, the power supply current is 2A, the power supply duty cycle is 50%, the power supply frequency is 60kHz, the pulse negative bias is 300V, the pulse negative bias duty cycle is 40%, and the sputtering time is 2h to obtain a diamond-like coating;

[0049] k. Repeat the above process to deposit the same diamond-like coating on the other side of the carbon graphite / carbon nanotube layer.

[0050] The dynamic elastic modulus test and density test were performed on the final diaphragm sample, and the specific elasticity and loss factor of the diaphragm were calculated. The specific results are shown in Table 1.

[0051] Example 2

[0052] Different from Example 1, in this embodiment, the base metal used is a pure metal nickel sheet of 20mm×10mm×0.1mm. The dynamic elastic modulus test and density test are performed on the final diaphragm sample, and the specific elasticity and loss factor of the diaphragm are calculated. The specific results are shown in Table 1.

[0053] Example 3

[0054] Unlike Example 1, in this example, the spraying liquid consists of 4 parts melamine and 1.5 parts sucrose dissolved in 50 parts glycerol. The spraying liquid is sprayed onto the surface of the pure metal cobalt sheet. The total mass of melamine and sucrose deposited on the surface of the pure metal cobalt sheet is 600 mg / cm 2 The heat treatment temperature is 1000℃ and the heat treatment time is 6h.

[0055] When preparing diamond-like carbon coatings by high-energy pulsed magnetron sputtering, the argon inlet flow rate was 400 sccm, the acetylene inlet flow rate was 40 sccm, the distance between the sample stage and the magnetron sputtering target was 15 cm, and the sample stage rotational speed was 5 rpm. During sputtering, the power supply current was 6 A, the power supply duty cycle was 60%, the power supply frequency was 80 kHz, the pulsed negative bias voltage was 500 V, the pulsed negative bias duty cycle was 50%, and the sputtering time was 4 hours.

[0056] The dynamic elastic modulus test and density test were performed on the final diaphragm sample, and the specific elasticity and loss factor of the diaphragm were calculated. The specific results are shown in Table 1.

[0057] Example 4

[0058] Unlike Example 1, in this example, when preparing a diamond-like carbon coating by high-energy pulsed magnetron sputtering, the argon gas flow rate was 400 sccm, the acetylene gas flow rate was 40 sccm, the distance between the sample stage and the magnetron sputtering target was 15 cm, and the sample stage rotational speed was 5 rpm. During sputtering, the power supply current was 6 A, the power supply duty cycle was 60%, the power supply frequency was 80 kHz, the pulsed negative bias voltage was 500 V, the pulsed negative bias duty cycle was 50%, and the sputtering time was 4 hours.

[0059] The dynamic elastic modulus test and density test were performed on the final diaphragm sample, and the specific elasticity and loss factor of the diaphragm were calculated. The specific results are shown in Table 1.

[0060] Table 1. Specific elastic modulus and loss factor of diaphragm samples obtained under different conditions

[0061] Diaphragm samples <![CDATA[Specific modulus × 10 6 (m 2 / s 2 )]]> <![CDATA[Loss factor × 10 -2 (tanθ)]]> Example 1 32.62 6.07 Example 2 28.41 5.45 Example 3 38.27 6.74 Example 4 42.52 5.11

[0062] In summary, the diaphragm obtained by the present invention includes a carbon graphite / carbon nanotube layer and a diamond-like coating. The carbon nanotubes are interwoven to form a porous membrane with a macroscopic membrane-like morphology and a microscopic network structure. The carbon graphite is interspersed in the internal gaps of the carbon nanotube porous membrane. The carbon graphite and carbon nanotubes together form a carbon graphite / carbon nanotube layer with a relatively dense internal structure, and a diamond-like coating with high specific elasticity, high bending rigidity and high internal damping is deposited on its surface to obtain a diaphragm with excellent comprehensive performance. The diaphragm has good acoustic effects, good moisture-proof performance, good mildew resistance, low production cost and simple preparation method.

[0063] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0064] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A diaphragm, characterized in that: The diaphragm includes an intermediate layer and a coating coated on both surfaces of the intermediate layer, the intermediate layer is a carbon graphite / carbon nanotube layer, the carbon graphite / carbon nanotube layer includes carbon graphite and carbon nanotubes, the carbon nanotubes are an interwoven structure, the carbon graphite exists in the gaps between the interwoven carbon nanotubes, the carbon graphite / carbon nanotube layer is prepared by a high-temperature carbonization-in-situ growth method, and the coating is a diamond-like coating.

2. The diaphragm according to claim 1, wherein The thickness of the diaphragm is 54 μm-216 μm.

3. The diaphragm according to claim 1, wherein The thickness of the carbon graphite / carbon nanotube layer is 50 μm-200 μm.

4. The diaphragm according to claim 1, wherein The thickness of the diamond-like carbon coating is 2 μm-8 μm.

5. A method for preparing the diaphragm according to any one of claims 1 to 4, characterized in that: The method is as follows: S1, preparing a carbon graphite / carbon nanotube layer, wherein the thickness of the carbon graphite / carbon nanotube layer is 50 μm-200 μm; S2. Depositing a diamond-like coating on both surfaces of the carbon graphite / carbon nanotube layer, wherein the thickness of the diamond-like coating is 2 μm-8 μm.

6. The method for preparing a diaphragm according to claim 5, wherein: The diamond-like coating is prepared by a high-energy pulse magnetron sputtering method.

7. The method for preparing a diaphragm according to claim 6, wherein: The conditions of the high-energy pulse magnetron sputtering are: power supply current is 1A-8A, power supply duty cycle is 40%-80%, power supply frequency is 40kHz-100kHz, pulse negative bias is 200V-1000V, pulse negative bias duty cycle is 30%-60%, and sputtering time is 0.5h-5h.

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