Boron nitride composite film and preparation method thereof

Abstract

The present invention discloses a boron nitride composite film and a preparation method thereof, by adding graphene oxide to boron nitride, so that the thermal conductivity of the boron nitride film is significantly improved. During the reduction process of graphene oxide, the oxygen-containing functional groups between its layers are removed, resulting in an increase in the interlayer spacing. This expansion effect can provide space for the peeling of boron nitride, making it easier to separate the boron nitride layers. In addition, graphene acts as an isolating agent between the boron nitride layers, which can prevent the boron nitride layers from restacking during the peeling process, maintain a high specific surface area and active sites, and can also reduce thermal interface resistance and promote phonon transmission through interface coupling optimization. The thermal conductivity of the prepared boron nitride composite film can reach 50-70W / m·K.

Description

Technical Field

[0001] The present invention belongs to the field of functional films, and in particular relates to a boron nitride composite film and a preparation method thereof. Background Art

[0002] The main preparation methods of boron nitride thin films are co-blending modification and vapor deposition. Co-blending modification is to disperse boron nitride (BN) nanosheets or particles in a polymer material solution to form a coating slurry. This slurry can then be applied to a substrate through various coating techniques to form a boron nitride composite film. Another way is to directly mix boron nitride with a polymer material and cast it into a film through a high-temperature melting process. Physical vapor deposition (PVD) or chemical vapor deposition (CVD) are common methods for preparing high-quality boron nitride films. In the PVD process, evaporation, sputtering and other techniques are usually used to transfer the substance from the source material to the substrate to form a thin film. In the CVD process, the precursor gas is decomposed by chemical reaction in a gaseous environment and deposited on a heated substrate to form a thin film.

[0003] However, the improvement of thermal conductivity through blending modification is limited. The yield of boron nitride thin films prepared by vapor deposition is too low, the film quality is poor, and large-scale production is impossible. Summary of the Invention

[0004] In response to the above problems, the present invention provides a boron nitride composite film and a preparation method thereof, which effectively improves the thermal conductivity of the boron nitride film.

[0005] One of the technical solutions of the present invention is to provide a method for preparing a boron nitride composite film, comprising the following steps:

[0006] (1) Boric acid and melamine are uniformly mixed in a mass ratio of 0.8-1.1, reacted at 300-350°C for 3-5 hours under a nitrogen environment, and the reaction product is ground to a particle size of 1-10 μm to obtain material A - uncrystallized boron nitride.

[0007] (2) Grind graphene oxide powder to 0.5-5 μm, add it to material A, and mix evenly, wherein the content of graphene oxide is 1-10 wt%, to obtain material B.

[0008] (3) Material B is treated at 1000-2000°C for 4-6 hours under a vacuum environment, cooled to room temperature, and pulverized by air flow to a particle size of no more than 100 μm, washed with water, and dried to obtain material C.

[0009] During the thermal reduction process, oxygen-containing functional groups (such as hydroxyl and epoxy groups) in graphene oxide decompose, producing gases (such as CO₂ and H₂O). The release of these gases increases interlayer pressure, causing expansion between the GO layers. This process helps partially restore the sp² carbon network structure and provides physical shear forces between adjacent BN layers, promoting BN exfoliation. Furthermore, the reduced graphene acts as a spacer between the BN layers, preventing restacking and maintaining a high specific surface area and active sites. It also reduces thermal interface resistance through interfacial coupling optimization, promoting phonon transmission.

[0010] (4) Material C was treated at 2600-3000°C for 0.5-1.5 hours under an argon environment, cooled to room temperature, and pulverized with air flow to a particle size of no more than 100 μm to obtain material D.

[0011] (5) Material D, a dispersant, and water are treated by microfluidization to obtain a uniform and stable slurry E, wherein the mass percentage of material D is 5-30% and the mass percentage of the dispersant is 0.1-1%; the dispersant is sodium dodecylbenzenesulfonate.

[0012] (6) Slurry E is coated and dried at 60-90°C to obtain a boron nitride composite film with a thickness of 17-120 μm.

[0013] After GO is reduced to graphene, the exfoliated BN forms an interpenetrating three-dimensional network with the graphene. This synergistic effect reduces interfacial thermal resistance, resulting in a composite material with a thermal conductivity 2-5 times higher than that of the individual components. Furthermore, the graphitization process reduces grain boundaries and vacancy defects, which in turn reduces phonon scattering, further enhancing overall thermal conductivity.

[0014] The second technical solution of the present invention is to provide a boron nitride composite film prepared by the above method.

[0015] The beneficial effects of the present invention are as follows: the expansion and delamination of graphene oxide during the carbonization and graphitization stage is beneficial to the delamination of boron nitride and improves the delamination effect.

[0016] The product has a higher thermal conductivity, as graphene has a high thermal conductivity and boron nitride exfoliation and dispersion is better. The reduced graphene acts as a separator between the BN layers, preventing them from restacking and maintaining a high specific surface area and active sites. It also reduces thermal interface resistance and promotes phonon transmission through interface coupling optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a cross-sectional structural diagram of the present invention. DETAILED DESCRIPTION

[0018] The following examples are used to further illustrate the present invention. Their purpose is to illustrate the present invention and should not be construed as limiting the scope of the present invention. Unless otherwise specified, all references are by weight and weight percentage.

[0019] Unless otherwise specified, the raw materials used in the present invention are conventional commercial products; the methods used in the present invention are conventional methods in the art unless otherwise specified.

[0020] The embodiments of the present invention are further described below with reference to a number of embodiments.

[0021] It should be clear that the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0022] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The singular forms "a", "an", "the" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0023] Example 1

[0024] (1) Boric acid and melamine were uniformly mixed in a mass ratio of 0.8, reacted at 300°C in nitrogen for 3 hours, and the reaction product was ground to a particle size of 1 μm to obtain material A;

[0025] (2) Grinding graphene oxide powder to 0.5 μm, adding it to material A, and mixing evenly, wherein the content of graphene oxide is 1 wt%, to obtain material B;

[0026] (3) Material B was treated at 1000°C in a vacuum environment for 4 hours, cooled to room temperature, and pulverized with air flow to a particle size of no more than 100 μm, washed with water, and dried to obtain material C;

[0027] (4) Material C was treated at 2600°C for 0.5 hours under an argon atmosphere, cooled to room temperature, and pulverized with air flow to a particle size of no more than 100 μm to obtain material D;

[0028] (5) Material D, dispersant, and water are treated by microfluidization to obtain a uniform and stable slurry E, in which the mass percentage of material D is 5% and the mass percentage of dispersant is 0.1%;

[0029] (6) The slurry E was coated and dried at 60°C to obtain a boron nitride composite film with a thickness of 17 μm. The thermal conductivity of the obtained boron nitride composite film was 51.170 W / m·K. Figure 1As shown, the film is a sheet-like structure stacked layer by layer.

[0030] Table 1 Thermal conductivity parameters of boron nitride composite film in Example 1

[0031]

[0032] Example 2

[0033] (1) Boric acid and melamine were uniformly mixed in a mass ratio of 1.1, reacted at 350°C in nitrogen for 5 hours, and the reaction product was ground to a particle size of 10 μm to obtain material A;

[0034] (2) Grinding graphene oxide powder to 5 μm, adding it to material A, and mixing evenly, wherein the content of graphene oxide is 10 wt%, to obtain material B;

[0035] (3) Material B was treated at 2000°C in a vacuum environment for 6 hours, cooled to room temperature, and pulverized with air flow to a particle size of no more than 100 μm, washed with water, and dried to obtain material C;

[0036] (4) Material C was treated at 3000°C for 1.5 hours in argon, cooled to room temperature, and pulverized in air flow to a particle size of no more than 100 μm to obtain material D;

[0037] (5) Material D, dispersant, and water are treated by microfluidization to obtain a uniform and stable slurry E, in which the mass percentage of material D is 30% and the mass percentage of dispersant is 1%;

[0038] (6) Slurry E was applied and dried at 90°C to obtain a 120 μm thick boron nitride composite film with a thermal conductivity of 70.552 W / m·K.

[0039] Table 2 Thermal conductivity parameters of boron nitride composite film in Example 2

[0040]

[0041] Comparative Example 1

[0042] (1) Boric acid and melamine were uniformly mixed in a mass ratio of 1.1, reacted at 350°C in a nitrogen environment for 5 hours, and the reaction product was ground to a particle size of 1-10 μm to obtain material A;

[0043] (2) Material A was treated at 2000°C in a vacuum environment for 6 hours, cooled to room temperature, and pulverized to a particle size of 100 μm using air flow, washed with water, and dried to obtain material B;

[0044] (3) Material B was treated at 3000°C for 1.5 hours in argon, cooled to room temperature, and pulverized in air flow to a particle size of 100 μm to obtain material C;

[0045] (4) Material C, dispersant, and water are treated by microfluidization to obtain a uniform and stable slurry D, in which the mass percentage of material D is 30% and the mass percentage of dispersant is 1%;

[0046] (5) Slurry D was applied and dried at 90°C to obtain a 120 μm thick boron nitride film. The thermal conductivity of the obtained boron nitride film was 42.995 W / m·K.

[0047] Table 3 Thermal conductivity parameters of boron nitride film in comparative example 1

[0048]

[0049] The above embodiments describe in detail the structure, features and effects of the present invention. The above are only preferred embodiments of the present invention. Any changes made in accordance with the concept of the present invention, or modifications to equivalent embodiments with equivalent changes, which do not exceed the scope covered by the specification, should be within the scope of protection of the present invention.

Claims

1. A method for preparing a boron nitride composite film, characterized in that: The following steps are involved: (1) After mixing uncrystallized boron nitride and graphene oxide with a size of 0.5-5 μm, the mixture is subjected to the following two-step heat treatment: treating at 1000-2000°C for 4-6 hours in a vacuum environment; and treating at 2600-3000°C for 0.5-1.5 hours in an inert gas atmosphere; wherein the mass proportion of graphene oxide is 1-10wt%; the uncrystallized boron nitride is obtained by the following method: uniformly mixing boric acid and melamine in a mass ratio of 0.8-1.1, reacting at 300-350°C for 3-5 hours in an inert gas atmosphere to obtain uncrystallized boron nitride; (2) The coating formed by mixing the material after the two-step heat treatment, a dispersant and water is applied and dried to form a film to obtain a boron nitride composite film; the mixing method is microjet.

2. The method according to claim 1, characterized in that Also includes: The heat-treated product was crushed to a size of less than 100 μm.

3. The method according to claim 1, characterized in that In the coating, the material after two-step heat treatment accounts for 5-30% by mass, the dispersant accounts for 0.1-1% by mass, and the rest is water.

4. The method according to claim 1, wherein The coating and drying temperature is 60-90°C.

5. The method according to claim 1, wherein The uncrystallized boron nitride has a particle size of 1-10 μm.

6. The method according to claim 1, characterized in that The dispersant is sodium dodecylbenzenesulfonate.

7. A boron nitride composite film prepared by the preparation method according to claim 1.

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