A microporous ceramic substrate and a microporous composite sound-absorbing and noise-reducing material containing the same and a preparation method thereof

Abstract

The present invention relates to the technical field of sound-absorbing and noise-reducing materials. Aiming at the problems that existing sound-absorbing and noise-reducing materials have poor sound absorption effect and a narrow sound absorption frequency range, the present invention specifically discloses a microporous ceramic substrate and a microporous composite sound-absorbing and noise-reducing material containing the same, and a preparation method thereof. The preparation method of the microporous ceramic substrate comprises the following steps: taking vanadium-titanium metallurgical blast furnace slag with a particle size of 0.1-3.0 mm, a binder and a sintering aid, and sequentially performing raw material drying, mixing, spreading, pressing and sintering; the sintering process comprises: first heating to 200-300° C. at 2-12° C. / min, then heating to 600-800° C. at 1-10° C. / min, and finally heating to 900-1180° C. at 0.5-10° C. / min, sintering at this temperature for 1-60 min, and cooling to obtain the microporous ceramic substrate. The microporous ceramic substrate has an appropriate pore size and is in the form of long and through holes, which can achieve sound absorption and noise reduction of sound waves, and realize efficient resource utilization of bulk solid waste vanadium-titanium blast furnace metallurgical slag.

Description

Technical Field

[0001] The present invention relates to the technical field of sound-absorbing and noise-reducing materials, and in particular to a microporous ceramic substrate and a microporous composite sound-absorbing and noise-reducing material containing the same, and a preparation method thereof. Background Art

[0002] Sound absorption and noise reduction refers to the use of sound-absorbing materials or suspended spatial absorbers to absorb sound energy indoors to reduce noise. It is a key measure in building environmental noise control technology. With the development of sound-absorbing materials and their structural forms, sound absorption and noise reduction technology is increasingly being used in industrial and civil building noise control. Sound-absorbing materials are materials that match the acoustic characteristic impedance of the surrounding sound-transmitting medium, allowing sound energy to enter the material without reflection and absorbing the vast majority of the incident sound energy. These materials absorb incident sound energy through their porosity, film action, or resonance.

[0003] Among the existing sound-absorbing and noise-reducing materials, each material can only absorb a limited range of sound wave frequencies. For example, traditional gypsum boards that can absorb low-frequency sound waves have little effect on sound waves in other bands and also rely on their bulky structural characteristics. Multi-porous sound-absorbing and noise-reducing materials can absorb medium and high-frequency sound waves, but are not very effective when facing low-frequency sound waves. In addition, in actual applications in fields such as construction, automobiles, and aerospace, materials are also required to have multiple performance characteristics such as light weight, thermal insulation, and fire resistance.

[0004] For example, patent publication number CN111302755A provides a composite building waterproof and thermal insulation material and its preparation method. The material utilizes a three-layer structure consisting of a waterproof layer, a nano-ceramic mycelium insulation layer, and a waterproof layer. The nano-ceramic mycelium insulation layer is primarily made of mycelium, limestone, nano-ceramic particles, and straw. The mycelium coats the limestone and nano-ceramic particles, creating a shell-like structure. This allows the organic matter in the mycelium to form a complex and variable composite material with the limestone and nano-ceramic particles, thereby achieving thermal insulation. The material is then pressed together with the waterproof layer using an adhesive to form a building material that is both thermally insulating and waterproof. However, the material absorbs a narrow frequency band of sound waves, meaning it cannot simultaneously absorb low, medium, and high-frequency sound waves. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem of poor sound absorption effect of existing sound-absorbing and noise-reducing materials, and further solve the problem of narrow frequency range of sound wave absorption, and realize the resource efficient utilization of bulk solid waste vanadium-titanium blast furnace metallurgical slag.

[0006] The present invention is achieved through the following technical solutions:

[0007] The present invention provides a method for preparing a microporous ceramic substrate, which is characterized by comprising the following steps:

[0008] A1 takes vanadium-titanium metallurgical blast furnace slag, binder and sintering aid, and sequentially carries out raw material drying, mixing, spreading and pressing;

[0009] Among them, the particle size of vanadium-titanium metallurgical blast furnace slag is 0.1-5.0mm;

[0010] A2 is then sintered as follows: first heating to 200-300°C at 2-12°C / min, then heating to 600-800°C at 1-10°C / min, and finally heating to 900-1180°C at 0.5-10°C / min, sintering at this temperature for 1-60 minutes, and cooling to obtain the microporous ceramic substrate.

[0011] Preferably, the binder includes any one or more of silica sol, sodium silicate, aluminum silicate, and magnesium silicate.

[0012] Preferably, the sintering aid includes any one or more of borax, glass slag, glass fiber slag, sodium carbonate, limestone, dolomite, and fluorite. The use of this sintering aid, combined with the raw material system, can significantly reduce the temperature required for sintering, that is, a microporous ceramic substrate with the desired morphology and performance can be sintered at a lower temperature range.

[0013] Preferably, the sintering aid comprises, by weight, 5-10 parts of borax, 0-20 parts of glass slag, 0-20 parts of glass fiber slag, 0-10 parts of sodium carbonate, 0-10 parts of limestone, 0-10 parts of dolomite and 0-10 parts of fluorite.

[0014] Preferably, in step A1, by weight, the vanadium-titanium metallurgical blast furnace slag is 50-85 parts, the binder is 5-25 parts, and the sintering aid is 5-25 parts.

[0015] The present invention provides a microporous ceramic substrate prepared by the above preparation method. The porosity of the microporous ceramic substrate is 40-80%, preferably the average porosity is 65%, the noise reduction coefficient NRC of 4 cm thickness is 0.50-0.80, the compressive strength is ≥2 MPa, and the flexural strength is ≥1 MPa.

[0016] The present invention provides a microporous composite sound-absorbing and noise-reducing material, comprising a bottom layer, a middle layer, and a surface layer. The bottom layer is microporous mycelium, the middle layer is the above-mentioned microporous ceramic substrate, and the surface of the middle layer microporous ceramic substrate is sprayed with polylactic acid. The surface layer is polylactic acid-bamboo composite fiber. The middle layer microporous ceramic substrate and the bottom layer microporous mycelium are connected by chemical bonding.

[0017] The microporous mycelium includes a microporous carbon material and hyphae spores inoculated into the microporous carbon material. A large number of nanopores are formed between the hyphae spores and the microporous carbon material, and the pore diameter of the nanopores is 5-10 μm.

[0018] The polylactic acid-bamboo composite fiber is prepared by mixing polylactic acid and bamboo fiber through banburying, and a V-shaped groove is arranged on the surface of the polylactic acid-bamboo composite fiber.

[0019] Preferably, the thickness of the middle layer microporous ceramic substrate is 30-50 mm, the thickness of the surface layer polylactic acid-bamboo composite fiber is 0.1-0.5 mm, and the thickness of the bottom layer microporous mycelium is 0.3-2 mm. Those skilled in the art can also set the thickness of different layers of materials in a similar proportion.

[0020] Preferably, polylactic acid is used to fill the microporous ceramic substrate to adjust the pore size of the microporous ceramic substrate, and the filling amount of polylactic acid accounts for 10-50% of the pore volume of the microporous ceramic substrate by volume fraction, and the filling amount of polylactic acid decreases gradually from the inside of the microporous ceramic substrate to the surface of the microporous ceramic substrate.

[0021] Preferably, the depth of the V-grooves on the surface of the polylactic acid-bamboo composite fiber is 0.01-0.05 mm, and the groove spacing is 0.05-0.2 mm.

[0022] The present invention provides a method for preparing the above-mentioned microporous composite sound-absorbing and noise-reducing material, comprising the following steps:

[0023] S1 preparation of polylactic acid-bamboo composite fiber;

[0024] S2 preparation of polylactic acid filled microporous ceramic substrate;

[0025] S3 preparation of microporous mycelium;

[0026] S4: A polylactic acid-filled microporous ceramic substrate is taken, hydroxylated, and a silane coupling agent is added. The microporous mycelium is then placed on the bottom surface of the polylactic acid-microporous ceramic substrate, heated to 70-90°C and hot-pressed. The surface of the polylactic acid-microporous ceramic substrate is then covered with polylactic acid-bamboo composite fiber, heated to 80-100°C and hot-pressed again, and then cured and annealed to obtain the microporous composite sound-absorbing and noise-reducing material.

[0027] Preferably, in step S1, the preparation of polylactic acid-bamboo composite fiber specifically includes the following steps:

[0028] S1.1 Heat polylactic acid pellets and bamboo fiber to 160-190°C in a mass ratio of 3-4:1-2, and mix by internal mixing to obtain a fiber composite slurry;

[0029] S1.2 The fiber composite slurry is injected into a mold, heated to 120-150°C for hot pressing, and laser engraved to form a composite fiber body with V-shaped grooves on the surface;

[0030] S1.3 Spraying a perfluorosilane solution onto the surface of the composite fiber body, heating to 110-130° C., and curing to obtain a polylactic acid-bamboo composite fiber.

[0031] Preferably, in step S2, the preparation of the polylactic acid-filled microporous ceramic substrate specifically includes the following steps:

[0032] S2.1 Mixing and kneading the polylactic acid masterbatch and the silane coupling agent to form NH2-polylactic acid;

[0033] S2.2 The microporous ceramic substrate is placed in NH2-polylactic acid at a mass ratio of 5-7:3-5, and a solvent is added for impregnation; the substrate is then heated to 70-90°C for a curing reaction; and the substrate is then 3D printed to produce a polylactic acid-filled microporous ceramic substrate.

[0034] Preferably, in step S3, the preparation of the microporous mycelium specifically includes the following steps:

[0035] S3.1 Mixing the nanocarbon material with polylactic acid, dissolving the mixture in a solvent, and freeze-drying the mixture to obtain a microporous carbon material;

[0036] S3.1 Take a mycelial spore suspension and inoculate it into the microporous carbon material. Control the ambient humidity to 85-95% and the ambient temperature to 28-32°C. Inoculate and culture for 48-72 hours to obtain the microporous mycelium.

[0037] Preferably, the ratio of nano-carbon material to polylactic acid is 1:98-99.9 by mass; the concentration of mycelial spore suspension is 0.5×10 6 -2×10 6 CFU / mL, the dosage ratio of mycelial spore suspension to microporous carbon material is 1mL:0.5-2g.

[0038] The technical solution of the present invention has the following beneficial effects:

[0039] The microporous ceramic substrate in the present invention can be used as the basic material of multi-band sound-absorbing materials. The microporous ceramic substrate uses vanadium-titanium metallurgical blast furnace slag with a limited size structure as raw material, which can effectively realize the resource recycling and reuse of bulk solid waste vanadium-titanium blast furnace metallurgical slag. It has a wide source, is green and environmentally friendly, and is extremely suitable for actual production applications. Moreover, sintering is carried out under limited auxiliary agents and process conditions to obtain through holes with uniform pore size and dispersion. The tiny and lengthy through holes can exert extremely high interference intensity on medium and high frequency sound waves of 125-4000Hz, that is, by fully converting sound energy into heat energy, the effect of sound absorption and noise reduction is fundamentally achieved.

[0040] On the basis of the microporous ceramic substrate, the present invention also compounds multi-layer multi-scale structural materials, and absorbs sound waves of different frequency bands through different layer materials, thereby realizing multi-band sound absorption coverage of low-frequency sound waves to high-frequency sound waves by the microporous composite sound-absorbing and noise-reducing material; and the layered materials are connected through chemical bonding interfaces to achieve the compatibility and combination of inorganic and organic materials, which can improve the bonding strength and performance stability of the composite material.

[0041] Specifically, the bottom layer of microporous mycelium grows in situ in the microporous material through mycelial spores to form an artificial biological composite network structure material, and utilizes this structure and other characteristics to achieve resonant sound absorption of low-frequency sound waves; the middle layer of microporous ceramic substrate serves as the base material, on the one hand, by filling gradient content of polylactic acid to induce multiple resonances, combined with the thermoelastic effect of polylactic acid to dissipate sound energy, thereby achieving sound absorption of medium and high frequency sound waves; on the other hand, elastic polylactic acid is filled in the microporous ceramic substrate, which can improve the toughness of the material while having high strength, and serve as a strong mechanical support material; the surface layer of polylactic acid-bamboo composite fiber induces multiple refractions of sound waves through the pores of bamboo fibers, and viscous friction converts sound energy into heat energy. Moreover, high-frequency sound waves have a shorter wavelength and are more likely to form shear stress with air turbulence, so that the energy of the sound waves is converted into heat energy due to friction and internal dissipation in this flow, so as to weaken the intensity of the sound waves, that is, to achieve sound absorption of high-frequency sound waves. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those skilled in the art, other relevant drawings can be obtained based on these drawings without creative work.

[0043] Figure 1 This is an electron microscope image of the microporous ceramic substrate in Example 1 magnified 700 times. DETAILED DESCRIPTION

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed; and where the manufacturers of the instruments, equipment, reagents, and raw materials used are not specified, they are all commercially available conventional products.

[0045] The present invention provides a microporous ceramic substrate, the preparation method of which comprises the following steps:

[0046] (1) Take 50-85 parts by weight of vanadium-titanium metallurgical blast furnace slag, 5-25 parts by weight of binder and 5-25 parts by weight of sintering aid, and carry out raw material drying, mixing, laying and pressing in sequence, and the compression ratio of the molding volume to the volume before compression is 10%-30%;

[0047] Among them, the particle size of the vanadium-titanium metallurgical blast furnace slag is 0.1-5.0 mm, and the moisture content is 0-5wt%; the binder includes any one or more of silica sol, sodium silicate, aluminum silicate, and magnesium silicate; the sintering aid includes any one or more of borax, glass slag, glass fiber slag, sodium carbonate, limestone, dolomite, and fluorite, and the moisture content of the sintering aid does not exceed 1wt%, and can preferably be a mixture of 5-10 parts of borax, 0-20 parts of glass slag, 0-20 parts of glass fiber slag, 0-10 parts of sodium carbonate, 0-10 parts of limestone, 0-10 parts of dolomite and 0-10 parts of fluorite.

[0048] (2) Sintering is then performed as follows: first heating to 200-300°C at 2-12°C / min, then heating to 600-800°C at 1-10°C / min, and finally heating to 900-1180°C at 0.5-10°C / min, sintering at this temperature for 1-60 minutes, and cooling to obtain the microporous ceramic substrate.

[0049] The microporous ceramic substrate of the present invention has a volume density of 800-1300 kg / m 3 The porosity is 40-80%, the pore size range is 0.2-0.3mm, the noise reduction coefficient (NRC) is 0.50-0.80 at a thickness of 4cm, the compressive strength is ≥2MPa, and the flexural strength is ≥1MPa. This microporous ceramic substrate has a strong sound absorption effect on medium and high frequency sound waves and can also be used as the skeleton base material of composite sound-absorbing materials.

[0050] The present invention provides a microporous composite sound-absorbing and noise-reducing material, comprising a bottom layer, a middle layer and a surface layer. The bottom layer is microporous mycelium, the middle layer is the above-mentioned microporous ceramic substrate, and the surface of the middle layer microporous ceramic substrate is sprayed with polylactic acid, and the surface layer is polylactic acid-bamboo composite fiber; and the middle layer polylactic acid-microporous ceramic substrate and the bottom layer microporous mycelium are connected by chemical bonding.

[0051] The thickness of the middle microporous ceramic substrate is 30-50 mm, the thickness of the surface polylactic acid-bamboo composite fiber is 0.1-0.5 mm, and the thickness of the bottom microporous mycelium is 0.3-2 mm. Those skilled in the art can also adjust the thickness of the different layers of materials in a similar proportion. The microporous ceramic substrate used in the middle layer of the present invention has significant sound absorption and noise reduction effects. Furthermore, the surface and bottom layers are applied to further comprehensively absorb sound waves of excessively high or low frequencies, achieving the effect of absorbing sound waves across a wider frequency range, thereby enhancing the overall sound absorption effect of the composite material.

[0052] In the present invention, the method for preparing microporous mycelium comprises the following steps:

[0053] A1: taking nanocarbon material and polylactic acid, and controlling the mass fraction of the nanocarbon material to be 0.5-2%, mixing them, dissolving them in a solvent, placing them at -60°C to -40°C, and performing vacuum freeze drying to obtain a microporous carbon material;

[0054] The ratio of nanocarbon material to polylactic acid is 1:98-99.9, and the concentration of mycelial spore suspension is 0.5×10 6 -2×10 6 CFU / mL, the usage ratio of mycelial spore suspension to microporous carbon material is 1mL:0.5-2g; the obtained microporous carbon material has a pore size of 1-10μm.

[0055] A2: Inoculate the mycelial spores into the microporous carbon material, control the ambient humidity to 85-95% and the ambient temperature to 28-32°C, and culture for 48-72 hours to obtain a microporous mycelium with an interpenetrating mycelial network structure through in situ growth;

[0056] Among them, the hyphae spores are preferably Aspergillus niger, and the diameter of the formed hyphae network structure is 5-10 μm; the microporous mycelium can be connected to the hydroxyl groups on the surface of the middle layer polylactic acid-microporous ceramic substrate through a medium silane coupling agent to form Si-OC covalent bonds.

[0057] The nanopores of the microporous carbon material prepared by freeze-drying can form an equivalent Helmholtz resonance cavity, and the mycelium network and the microporous carbon material form a three-dimensional interpenetrating structure after cultivation. The interlayer bonding strength can be improved through bonding enhancement, thereby achieving long-term and stable resonant sound absorption of low-frequency sound waves of 100-500Hz.

[0058] In the present invention, the polylactic acid-filled microporous ceramic substrate in the middle layer is prepared by the following steps:

[0059] B1: Mixing and kneading the polylactic acid masterbatch and the silane coupling agent to form NH2-polylactic acid;

[0060] B2. The microporous ceramic substrate is then placed in an NH2-PLA / chloroform solution with a mass ratio of 5-7:3-5. The substrate is immersed in a negative pressure environment of -0.3 to -0.05 MPa for 15-45 minutes, then heated to 70-90°C and cured for 1-3 hours to fill the pores and form an interpenetrating network structure. Finally, 3D printing is performed to form a PLA-filled microporous ceramic substrate with a uniform gradient of PLA filling rate.

[0061] The mass concentration of polylactic acid in the NH2-polylactic acid / chloroform solution is 15-25wt%; the microporous ceramic substrate is filled with polylactic acid to adjust the pore size of the microporous ceramic substrate, and the filling amount of polylactic acid accounts for 10-50% of the pore volume of the microporous ceramic substrate by volume fraction. The filling amount of polylactic acid decreases gradually from the inside of the microporous ceramic substrate to the surface of the microporous ceramic substrate. Preferably, the filling rate of polylactic acid closest to the surface of the microporous ceramic substrate is 10%, and the filling rate of polylactic acid close to the inside of the microporous ceramic substrate is 50%, and the filling rate of polylactic acid changes in a gradient.

[0062] The polylactic acid-filled pore structure with a gradient filling rate of 40-60% triggers multiple resonances, and the thermoelastic effect of polylactic acid dissipates sound energy, achieving sound absorption of medium and high frequency sound waves of 500-2000Hz, with a sound absorption coefficient of approximately 0.65-0.8; the microporous ceramic substrate has good compressive strength, and the filled polylactic acid can improve toughness, thereby acting as a mechanical support.

[0063] In the present invention, the polylactic acid-bamboo composite fiber is prepared by spraying a fiber composite slurry onto the surface of a microporous ceramic substrate, wherein the preparation method of the fiber composite slurry comprises the following steps:

[0064] Polylactic acid particles and bamboo fibers are mixed at a mass ratio of 3-4:1-2, placed at 160-190°C, and kneaded to obtain a fiber composite slurry;

[0065] The diameter of bamboo fiber is controlled at 10-50μm, and is randomly distributed during the mixing process to form micron-scale pores of 50-100μm to enhance the viscous dissipation of sound waves.

[0066] The polylactic acid-bamboo composite fiber arranged on the surface causes multiple refractions of sound waves through the pores of the bamboo fiber. Viscous friction converts sound energy into heat energy. The high-frequency sound waves have a shorter wavelength and are more likely to form shear stress with air turbulence, so that the energy of the sound waves is converted into heat energy due to friction and internal dissipation in this flow, thereby reducing the intensity of the sound waves, that is, achieving sound absorption of high-frequency sound waves of 2-6kHz, and the sound absorption coefficient is approximately 0.85-0.92; and the V-shaped groove destroys the sound wave boundary layer and reduces surface friction noise by suppressing turbulence.

[0067] The preparation method of the microporous composite sound-absorbing and noise-reducing material of the present invention comprises the following steps:

[0068] (1) First, a microporous ceramic substrate with a middle layer filled with polylactic acid is taken and hydroxylated. The substrate can be activated by ultrasonic H2O2 to form a polylactic acid-microporous ceramic substrate with a large amount of -OH on the surface.

[0069] (2) Adding a silane coupling agent to the treated polylactic acid-microporous ceramic substrate, and then placing the microporous mycelium on the bottom layer of the polylactic acid-microporous ceramic substrate, placing it at 70-90°C and performing hot pressing at 0.3-0.8 MPa to form a mycelium-ceramic interface bond.

[0070] During the cultivation process, the mycelium secretes extracellular polysaccharides, which can form a hydrogen bond network with the silane coupling agent on the surface of the polylactic acid-microporous ceramic substrate, thereby achieving a stable connection through chemical bonding; the silane coupling agent hydrolyzes to generate Si-OH, which condenses with the -OH on the surface of the ceramic skeleton. The -COOH at the end of the polylactic acid chain undergoes an amidation reaction with the -NH2 of the silane coupling agent. The amide bond between the hydroxyl groups on the ceramic surface and the polylactic acid can be mediated by the silane coupling agent, that is, the microporous mycelium and the polylactic acid-microporous ceramic substrate are strongly bonded with the silane coupling agent as a medium.

[0071] (3) Spraying fiber composite slurry onto the surface of the polylactic acid-microporous ceramic substrate, specifically, by using existing nano-scale coating spraying methods such as thermal spraying and vapor deposition, heating to 120-150 ° C for curing, and forming a V-shaped groove with a thickness of about 0.01-0.05 mm on the surface through 1064 nm fiber laser engraving, and spraying perfluorosilane solution, and controlling its contact angle to be greater than 150° to prevent pore clogging; heating to 110-130 ° C again for curing to form a surface polylactic acid-bamboo composite fiber, and then annealing at 120-150 ° C to eliminate internal stress, thus obtaining a microporous composite sound absorption and noise reduction material.

[0072] Among them, the depth of the V-groove is controlled to be 0.01-0.05mm, the groove spacing is 0.05-0.2mm, and it is parallel to the incident direction of the sound wave, which can destroy the boundary layer turbulence and suppress the eddy noise.

[0073] The following Examples 1 to 5 are various embodiments for preparing microporous ceramic substrates:

[0074] Example 1

[0075] This embodiment uses vanadium-titanium metallurgical blast furnace slag from Sichuan Desheng Group Vanadium Titanium Co., Ltd. as the base material, and its composition is shown in Table 1:

[0076] Table 1 Composition of vanadium-titanium metallurgical blast furnace slag (content: by mass percentage)

[0077]

[0078] Take 62.5g of vanadium-titanium metallurgical blast furnace slag, 2g of silica sol, 12.6g of sodium silicate, 7.3g of borax, 2.1g of sodium carbonate, 2g of limestone and 1.8g of fluorite, mix and ball mill until the particle size of the vanadium-titanium metallurgical blast furnace slag is controlled at 2.0±0.2mm to obtain a primary mixture; the primary mixture is piled up and laid out, and then pressed under a pressure of 5MPa until its volume is compressed to about 20% of that when laid out, to obtain a compact of about 4cm thick; and then sintered, first heated to 250±20℃ at 8℃ / min, then heated to 700±20℃ at 5℃ / min, and finally heated to 1050±20℃ at 4.5℃ / min, sintered for 0.45h, and cooled to room temperature within 10h to obtain a microporous ceramic substrate.

[0079] Example 2

[0080] The difference between this embodiment and embodiment 1 is that during the sintering process, the temperature is first raised to 290±10°C at 10°C / min, then raised to 750±20°C at 7°C / min, and finally heated to 1050±20°C at 8°C / min, and sintered at this temperature for 0.45h.

[0081] Example 3

[0082] The difference between this embodiment and embodiment 1 is that during the sintering process, the temperature is first raised to 220±10°C at 10°C / min, then raised to 620±20°C at 5°C / min, and finally heated to 950±20°C at 3°C / min, and sintered for 1 hour.

[0083] Example 4

[0084] The difference between this embodiment and embodiment 1 is that the primary mixed material includes 53.4 g of vanadium-titanium metallurgical blast furnace slag, 2 g of silica sol, 12.6 g of sodium silicate, 7.3 g of borax, and 5 g of glass.

[0085] Example 5

[0086] The difference between this embodiment and embodiment 1 is that the primary mixed material includes 80g of vanadium-titanium metallurgical blast furnace slag, 2g of silica sol, 12.6g of sodium silicate, 7.3g of borax, 4.5g of glass, and 4g of dolomite.

[0087] The following Examples 6-12 are various embodiments for preparing microporous composite sound-absorbing and noise-reducing materials:

[0088] Example 6

[0089] Step 1: Take 5.5g of polylactic acid masterbatch and 2.36g of bamboo fiber with a particle size of 20-30μm respectively, place them in an internal mixer, heat to 170℃, and mix them to obtain a fiber composite slurry.

[0090] Step 2: Take an equimolar amount of polylactic acid masterbatch and KH-550 silane coupling agent and mix them to form NH2-polylactic acid; take the 40 mm thick microporous ceramic substrate in Example 1 and the above-mentioned NH2-polylactic acid at a mass ratio of 6:3.85, mix them, add them to the chloroform solution, control the mass concentration of polylactic acid in the mixed solution to be 20%, place it in a -0.1 MPa environment and immerse it for 30 minutes, then heat it to 80±5°C, and cure it for 2 hours. Use FDM to print out the direction from the inside to the surface of the microporous ceramic substrate, and the polylactic acid PLA volume filling rate is 10%, 20%, 30%, 40%, and 50% respectively. Polylactic acid-filled microporous ceramic substrates.

[0091] Step 3: Take carbon nanotubes (CNTs) and polylactic acid (PLA) respectively, with the mass fraction of CNT being 1.0%, dissolve them in equimolar amounts of chloroform solution, place them at -50°C for vacuum freeze drying, and obtain microporous carbon materials; take the concentration of 1×10 6 CFU / mL of Aspergillus niger mycelial spore suspension, and the Aspergillus niger mycelial spore suspension and the microporous carbon material are taken at a ratio of 1mL:1g, the two are mixed, placed in an environment with a humidity of 90% and a temperature of 30°C, and cultured for 60h to obtain microporous mycelium.

[0092] Step 4: Take a polylactic acid-filled microporous ceramic substrate, add it to an equal mass of H2O2 solution, the mass concentration of the H2O2 solution is 15%, and adjust its pH value to about 8.2 by adding a small amount of ammonia water. After mixing, place it in 120W ultrasound and treat it at 45°C for 20 minutes. Then rinse and dry it to obtain a hydroxylated polylactic acid-filled microporous ceramic substrate; then add an equal molar amount of KH-550 silane coupling agent to the polylactic acid-filled microporous ceramic substrate, and then cover the microporous mycelium on the bottom layer of the polylactic acid-filled microporous ceramic substrate, and control the thickness of the microporous mycelium to be about 1 mm. Place it at 80±5°C and perform hot pressing at 0.5MPa to form a mycelium-ceramic chemical bond interface.

[0093] Step 5: Spray a fiber composite slurry with a thickness of about 0.2 mm onto the surface of the polylactic acid-filled microporous ceramic substrate, heat it to 130°C, and cure it for 15 minutes; then use a 1064 nm fiber laser to engrave a number of V-grooves about 0.02 mm thick on its surface, and the spacing between adjacent grooves is 0.1 mm; finally, spray a perfluorosilane solution with a contact angle greater than 150° onto the surface with the V-grooves, heat it to 120°C, and cure it for 30 minutes to form a polylactic acid-bamboo composite fiber surface layer, and finally anneal it at 130±5°C to obtain a microporous composite sound absorption and noise reduction material.

[0094] Example 7

[0095] The difference between this embodiment and embodiment 6 is that in step 2, a microporous ceramic substrate with a thickness of about 50 mm prepared by the method of embodiment 1 is used.

[0096] Example 8

[0097] The difference between this embodiment and embodiment 6 is that in step 2, the volume filling rates of the polylactic acid (PLA) from the inside to the surface of the microporous ceramic substrate are 10% and 50% respectively.

[0098] Example 9

[0099] The difference between this embodiment and embodiment 6 is that in step 5, the depth of the V-shaped grooves on the surface of the polylactic acid-bamboo composite fiber is about 0.01 mm, and the groove spacing is about 0.06 mm.

[0100] Example 10

[0101] The difference between this embodiment and embodiment 6 is that in step 5, the thickness of the fiber composite slurry is about 0.1 mm.

[0102] Example 11

[0103] The difference between this embodiment and embodiment 6 is that in step 3, the concentration of the Aspergillus niger mycelial spore suspension is 0.5×10 6 CFU / mL, and the ratio of Aspergillus niger hyphae spore suspension to microporous carbon material is 1mL:1.8g.

[0104] Example 12

[0105] The difference between this embodiment and embodiment 6 is that in step 4, the thickness of the microporous mycelium coated on the bottom layer of the polylactic acid filled microporous ceramic substrate is about 0.5 mm.

[0106] Comparative Example 1

[0107] The difference between this comparative example and Example 1 is that 50 g of vanadium-titanium metallurgical blast furnace slag with a particle size of about 1-1.5 mm is taken, pressed into a green body, heated to 1050±20°C at 8°C / min, sintered at this temperature for 2.5 hours, and cooled to room temperature within 10 hours to obtain a porous ceramic plate.

[0108] Comparative Example 2

[0109] The difference between this comparative example and comparative example 1 is that the sintering temperature is 1220±20°C.

[0110] Comparative Example 3

[0111] The difference between this comparative example and Example 6 is that the porous ceramic material prepared in Comparative Example 2 is used to replace the microporous ceramic substrate in step 2 of Example 6, and a multi-layer composite material is finally prepared.

[0112] Test example

[0113] (1) Take the microporous ceramic substrate in Example 1 and observe it under an electron scanning microscope. Under a magnification of 700 times, the following is obtained: Figure 1 The scanning electron microscope image of the microporous ceramic substrate is magnified 1000 times. Figure 1 It can be seen that the microporous ceramic substrate prepared by the method proposed in the present invention has uniform, tiny and penetrating through holes, which can play a significant role in sound absorption effect.

[0114] (2) The ceramic plates prepared in Examples 1 to 5 and Comparative Examples 1 to 2 were taken as samples, respectively. The compressive strength of the samples was tested according to GB / T1964-1996 "Test method for compressive strength of porous ceramics", the porosity of the samples was tested according to GB / T1966-1996 "Test method for apparent porosity and capacity of porous ceramics", and the noise reduction coefficient of the samples was tested according to GB / T18696.1-2004 "Measurement of sound absorption coefficient and acoustic impedance in acoustic impedance tubes Part 1: Standing wave ratio method". The test results are summarized in Table 2 below:

[0115] Table 2 Performance test results of different samples in Examples 1-5 and Comparative Examples 1-2

[0116]

[0117] As can be seen from Table 2 above, according to the measurement results, it can be found that the microporous ceramic substrates prepared by the method of the present invention in Examples 1 to 5 have an overall sound absorption and noise reduction effect that is significantly higher than the porous ceramic material prepared by the conventional method in Comparative Examples 1 to 2. Analysis shows that the sound absorption and noise reduction effect of the microporous ceramic substrate is based on the ceramic material obtained by the method of the present invention. The pore size distribution is uniform and the through holes are long and continuous, and it can also show outstanding advantages in the mechanical properties of compressive strength.

[0118] (3) The composite sound-absorbing and noise-reducing materials prepared in Examples 6-12 were respectively taken and the pore structures between different layers of the materials were observed by electron microscopy. The specific data are summarized in Table 3 below:

[0119] Table 3 Pore structure measurement results of different samples in Examples 6-12

[0120]

[0121] From the results measured in Table 3 above, it can be found that the microporous composite sound-absorbing and noise-reducing materials obtained by the method proposed in the present invention in Examples 6 to 12 can exhibit different pore structures at different layer depths, and materials with different pore structures can absorb sound waves of different frequency bands. That is, the microporous composite sound-absorbing and noise-reducing materials in the present invention can absorb sound waves of different frequency bands through the layer and pore structure of the material.

[0122] (4) The shear strength and other mechanical properties of Examples 6 to 12 and Comparative Example 3 were measured in accordance with GB / T 41501-2022 "Fiber-reinforced plastic composite materials - Determination of interlaminar shear strength and modulus by the double-beam method" and GB / T 9641-1988 "Test method for tensile properties of rigid foam plastics". The results are summarized in Table 4 below:

[0123] Table 4 Mechanical properties test results of different samples in Examples 6-12 and Comparative Example 3

[0124]

[0125] As can be seen from Table 4 above, compared with the multilayer composite material made of conventional porous ceramic material in Comparative Example 3, the microporous composite sound-absorbing and noise-reducing material and its preparation method proposed in the present invention, that is, the microporous composite sound-absorbing and noise-reducing material prepared in Examples 6 to 12, can exhibit significantly better mechanical properties such as bonding strength through connection effects such as chemical bonding.

[0126] (5) The sound absorption properties of the sound-absorbing and noise-reducing materials prepared in Examples 6 to 12 and Comparative Example 3 were measured in accordance with GB / T 18696.2-2002 "Measurement of Sound Absorption Coefficient and Acoustic Impedance in Acoustic Impedance Tubes". The results are summarized in Table 5 below:

[0127] Table 5 Sound absorption performance test results of different samples in Examples 6-12 and Comparative Example 3

[0128]

[0129] As can be seen from Table 5 above, compared with the multilayer composite material prepared by using conventional porous ceramic material as the substrate in Comparative Example 3, even when the core raw materials are the same, its absorption effect on sound waves in multiple frequency bands is significantly weaker than the composite sound-absorbing and noise-reducing materials prepared by using the microporous ceramic substrate and composite method proposed in the present invention in Examples 6 to 12. The microporous composite sound-absorbing and noise-reducing materials in Examples 6 to 12 have the performance effect of absorbing sound waves of different frequency bands at the same time, which means that the microporous composite sound-absorbing and noise-reducing material and its preparation method proposed in the present invention can solve the problem that the existing sound-absorbing and noise-reducing materials have poor sound absorption and noise reduction effects and cannot simultaneously absorb sound waves of low, medium and high frequencies, and can maintain strong mechanical properties such as bonding strength.

[0130] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A microporous composite sound-absorbing and noise-reducing material, characterized in that: The invention comprises a bottom layer, a middle layer and a surface layer, wherein the bottom layer is microporous mycelium, the middle layer is a microporous ceramic substrate, and the surface of the microporous ceramic substrate of the middle layer is sprayed with polylactic acid, and the surface layer is polylactic acid-bamboo composite fiber, and the microporous ceramic substrate of the middle layer is connected to the microporous mycelium of the bottom layer by chemical bonding; The microporous mycelium includes a microporous carbon material and hyphae spores inoculated into the microporous carbon material. A large number of nanopores are formed between the hyphae spores and the microporous carbon material, and the pore diameter of the nanopores is 5-10 μm. The polylactic acid-bamboo composite fiber is prepared by mixing polylactic acid and bamboo fiber through banburying, and a V-shaped groove is arranged on the surface of the polylactic acid-bamboo composite fiber.

2. The microporous composite sound-absorbing and noise-reducing material according to claim 1, characterized in that: The thickness of the middle-layer microporous ceramic substrate is 30-50 mm, the thickness of the surface polylactic acid-bamboo composite fiber is 0.1-0.5 mm, and the thickness of the bottom-layer microporous mycelium is 0.3-2 mm.

3. The microporous composite sound-absorbing and noise-reducing material according to claim 1, characterized in that: The microporous ceramic substrate is filled with polylactic acid to adjust the pore size of the microporous ceramic substrate, and the filling amount of polylactic acid accounts for 10-50% of the pore volume of the microporous ceramic substrate in terms of volume fraction. The filling amount of polylactic acid decreases gradually from the inside of the microporous ceramic substrate to the surface of the microporous ceramic substrate.

4. The microporous composite sound-absorbing and noise-reducing material according to claim 1, characterized in that: The depth of the V-shaped grooves on the surface of the polylactic acid-bamboo composite fiber is 0.01-0.05 mm, and the groove spacing is 0.05-0.2 mm.

5. A method for preparing the microporous composite sound-absorbing and noise-reducing material according to any one of claims 1 to 4, characterized in that: The steps include: S1 prepares fiber composite slurry; S2 Preparation of polylactic acid filled microporous ceramic substrate; S3 preparation of microporous mycelium; S4: Take a polylactic acid-filled microporous ceramic substrate, add a silane coupling agent, and then place the microporous mycelium on the bottom surface of the polylactic acid-microporous ceramic substrate, heat it to 70-90°C and hot press it; then spray the fiber composite slurry onto the surface of the polylactic acid-microporous ceramic substrate, heat it to 120-150°C and cure it, laser engrave a V-groove, spray it with a perfluorosilane solution, and heat it to 110-130°C again to cure it to form a surface layer of polylactic acid-bamboo composite fiber, which is then annealed to obtain the microporous composite sound-absorbing and noise-reducing material.

6. The method for preparing the microporous composite sound-absorbing and noise-reducing material according to claim 5, characterized in that: In step S1, the specific method for preparing the fiber composite slurry includes the following steps: Polylactic acid particles and bamboo fibers are taken in a mass ratio of 3-4:1-2, heated to 160-190° C., and mixed by internal kneading to obtain a fiber composite slurry.

7. The method for preparing the microporous composite sound-absorbing and noise-reducing material according to claim 5, characterized in that: In step S2, the specific method for preparing the polylactic acid filled microporous ceramic substrate includes the following steps: S2.1 Mixing and kneading the polylactic acid masterbatch and the silane coupling agent to form NH2-polylactic acid; S2.2 The microporous ceramic substrate is placed in NH2-polylactic acid at a mass ratio of 5-7:3-5, and a solvent is added for impregnation; the substrate is then heated to 70-90°C for a curing reaction; and the substrate is then 3D printed to produce a polylactic acid-filled microporous ceramic substrate.

8. The method for preparing the microporous composite sound-absorbing and noise-reducing material according to claim 5, characterized in that: In step S3, the preparation of microporous mycelium specifically includes the following steps: S3.1 Mixing the nanocarbon material with polylactic acid, dissolving the mixture in a solvent, and freeze-drying the mixture to obtain a microporous carbon material; S3.1 Take a mycelial spore suspension and inoculate it into the microporous carbon material. Control the ambient humidity to 85-95% and the ambient temperature to 28-32°C. Inoculate and culture for 48-72 hours to obtain the microporous mycelium.

9. The method for preparing the microporous composite sound-absorbing and noise-reducing material according to claim 8, characterized in that: The ratio of nanocarbon material to polylactic acid is 1:98-99.9 by mass; The concentration of mycelial spore suspension was 0.5×10 6 -2×10 6 CFU / mL, the dosage ratio of mycelial spore suspension to microporous carbon material is 1mL:0.5-2g.

10. A microporous ceramic substrate, characterized in that: The microporous ceramic substrate according to any one of claims 1 to 4, or the microporous ceramic substrate prepared by the preparation method according to any one of claims 5 to 9, wherein the porosity of the microporous ceramic substrate is 40-80%, the noise reduction coefficient NRC of 0.50-0.80 at a thickness of 4 cm, the compressive strength is ≥2 MPa, and the flexural strength is ≥1 MPa.

11. A method for preparing a microporous ceramic substrate according to claim 10, characterized in that: The steps include: A1 takes vanadium-titanium metallurgical blast furnace slag, binder and sintering aid, and sequentially carries out raw material drying, mixing, spreading and pressing; Among them, the particle size of vanadium-titanium metallurgical blast furnace slag is 0.1-5.0mm; A2 is then sintered as follows: first heating to 200-300°C at 2-12°C / min, then heating to 600-800°C at 1-10°C / min, and finally heating to 900-1180°C at 0.5-10°C / min, sintering at this temperature for 1-60 minutes, and cooling to obtain the microporous ceramic substrate.

12. The method for preparing a microporous ceramic substrate according to claim 11, wherein: The binder includes any one or more of silica sol, sodium silicate, aluminum silicate and magnesium silicate.

13. The method for preparing a microporous ceramic substrate according to claim 11, wherein: The sintering aids include any one or more of borax, glass slag, glass fiber slag, sodium carbonate, limestone, dolomite, and fluorite.

14. The method for preparing a microporous ceramic substrate according to claim 13, wherein: Calculated by weight, the sintering aid includes 5-10 parts of borax, 0-20 parts of glass slag, 0-20 parts of glass fiber slag, 0-10 parts of sodium carbonate, 0-10 parts of limestone, 0-10 parts of dolomite and 0-10 parts of fluorite.

15. The method for preparing a microporous ceramic substrate according to claim 11, wherein: In step A1, by weight, the vanadium-titanium metallurgical blast furnace slag is 50-85 parts, the binder is 5-25 parts, and the sintering aid is 5-25 parts.

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