A thin, lightweight, wideband underwater sound-absorbing material, its preparation method, and its application.

Abstract

This invention discloses a lightweight, thin, broadband underwater sound-absorbing material, its preparation method, and its applications, belonging to the technical field of underwater sound-absorbing materials and their preparation. This invention solves the problems of existing sound-absorbing coverings used in small and medium-sized underwater unmanned equipment being too heavy and having insufficient low-frequency sound absorption. This invention uses PDMS, whose characteristic impedance matches that of water, as a substrate and modifies it with the two-dimensional nanomaterial MXene to prepare a lightweight, thin, broadband underwater sound-absorbing material. First, the abundant surface functional groups of MXene enhance the interaction with the polymer, increasing the stability of the composite structure. Second, utilizing the two-dimensional layered structure, high specific surface area, and excellent thermal properties of MXene, the thermoacoustic conversion, P-wave and S-wave conversion, relaxation, and damping losses of the PDMS matrix are significantly enhanced with almost no increase in the weight of the composite material, thereby improving its underwater sound absorption performance.

Description

Technical Field

[0001] This invention relates to a thin, lightweight, wideband underwater sound-absorbing material, its preparation method, and its application, belonging to the technical field of underwater sound-absorbing materials and their preparation. Background Technology

[0002] Underwater sound-absorbing materials are a type of underwater acoustic functional material that is laid on the surface of underwater equipment to reduce its own noise. They have broad application prospects in regulating the noise of underwater equipment and reducing marine noise pollution.

[0003] Ideal underwater sound-absorbing materials must meet two important characteristics: first, their characteristic impedance should match that of water as closely as possible to reduce the reflection of incident sound waves; second, their attenuation performance needs to be sufficiently high to effectively absorb sound waves entering the material. Therefore, polymer materials that match the characteristic impedance of water are an excellent choice for underwater sound absorption. However, on the one hand, with the rapid development of small and medium-sized underwater unmanned equipment, there is a demand for underwater sound-absorbing materials to be as lightweight as possible; on the other hand, due to the significant impact of low-frequency noise, the operating frequency of underwater sound-absorbing materials needs to cover the low-frequency band below 1kHz. However, traditional polymer underwater sound-absorbing materials can no longer meet these underwater sound absorption requirements. Therefore, the development of lightweight, thin, and broadband novel underwater sound-absorbing materials is a key research focus in the field of underwater sound absorption. Summary of the Invention

[0004] This invention addresses the problems of existing sound-absorbing coverings used in small and medium-sized underwater unmanned equipment being too heavy and having insufficient low-frequency sound absorption effect, by providing a lightweight, thin, broadband underwater sound-absorbing material, its preparation method, and its application.

[0005] The technical solution of the present invention:

[0006] One objective of this invention is to provide a thin, lightweight, wideband underwater sound-absorbing material, which is obtained by compounding MXene colloidal solution, PDMS basic components and additives in a mass ratio of 2 to 35:50:1, adding PDMS curing agent, and then heating and curing.

[0007] Further specifying, the mass ratio of MXene colloidal solution, PDMS basic component and additives is 20-30:50:1.

[0008] Further specifying, the additive is a wetting and dispersing agent.

[0009] Further specifying, the adjuvants are DISPERBYK-191 and DISPERBYK-192.

[0010] To further specify, the MXene colloidal solution is obtained by chemical etching of MAX phase powder, followed by centrifugation, washing and centrifugation in dilute sulfuric acid, and then repeated washing and centrifugation with deionized water.

[0011] Further specified, the heating and curing temperature is 40–80℃.

[0012] The second objective of this invention is to provide a method for preparing the above-mentioned thin, wide-band underwater sound-absorbing material, the method comprising:

[0013] (1) Preparation of MXene colloidal solution;

[0014] The MAX phase powder was chemically etched, centrifuged, washed and centrifuged in dilute sulfuric acid, and then repeatedly washed and centrifuged with deionized water to obtain an MXene colloidal solution.

[0015] (2) Add MXene colloidal solution to the basic components of PDMS to obtain a modified mixed solution;

[0016] (3) Add PDMS curing agent to the modified mixed solution and then heat and cure to obtain a thin and wide-band underwater sound-absorbing material.

[0017] Further specifying, (1) the operation process includes the following steps:

[0018] S11: Dissolve lithium fluoride powder thoroughly in dilute hydrochloric acid by stirring.

[0019] S12: Add MAX phase powder to the mixed solution prepared in step S11 and heat and stir;

[0020] S13: After centrifuging the solution prepared in step S12, discard the supernatant and collect the precipitate;

[0021] S14: Stir the precipitate collected in step S13 in dilute sulfuric acid;

[0022] S15: Centrifuge the solution from step S14, discard the supernatant, and collect the precipitate, which is MXene;

[0023] S16: Add deionized water to wash the MXene precipitate prepared in step S15, centrifuge, and discard the supernatant;

[0024] S17: Repeat step S16 several times and test the pH value of the supernatant until it is near neutral.

[0025] S18: Continue washing and centrifuging the MXene precipitate. The black supernatant is the MXene colloidal solution. Repeat several times.

[0026] Furthermore, the concentration of dilute hydrochloric acid in step S11 is 8–10 mol / L.

[0027] Furthermore, the concentration of dilute hydrochloric acid in step S11 is 9 mol / L.

[0028] Furthermore, the mass ratio of lithium fluoride powder to dilute hydrochloric acid in step S11 is 1:14 to 14.5.

[0029] Furthermore, the mass ratio of lithium fluoride powder to dilute hydrochloric acid in step S11 is 1:14.2.

[0030] Furthermore, the stirring time in step S11 is specified as 30–90 min.

[0031] Furthermore, the stirring time in step S11 is 60–75 min.

[0032] Furthermore, in step S12, the MAX phase powder is a ternary layered carbon and / or nitride ceramic with the general chemical formula M. n+1 AX n Where M represents a pre-transition metal element, A represents a main group element, X represents carbon and / or nitrogen, and n is 1, 2, 3, or 4.

[0033] To further specify, the MAX phase powder in step S12 is Ti3AlC2.

[0034] Furthermore, in step S12, the mass ratio of MAX phase powder to lithium fluoride is 1:1 to 3.

[0035] Furthermore, in step S12, the mass ratio of MAX phase powder to lithium fluoride is 1:1.5 to 1.8.

[0036] Furthermore, the heating and stirring temperature in step S12 is 30–60°C, and the time is 12–72 h.

[0037] Furthermore, in step S12, the heating and stirring temperature is 35~45℃, and the time is 24~48h.

[0038] Furthermore, in step S13, the centrifugation speed is 3500–8000 rpm and the time is 5–30 min.

[0039] Furthermore, in step S13, the centrifugation speed is 5000–7000 rpm and the time is 10–15 min.

[0040] Furthermore, the concentration of dilute sulfuric acid in step S14 is 1–3 mol / L.

[0041] Furthermore, the concentration of dilute sulfuric acid in step S14 is 2 mol / L.

[0042] Furthermore, the mass ratio of the dilute sulfuric acid used in step S14 to the MAX phase powder in step S12 is 20.9 to 22.7:1.

[0043] Furthermore, the mass ratio of the dilute sulfuric acid used in step S14 to the MAX phase powder in step S12 is 21.8:1.

[0044] Furthermore, the stirring time in step S14 is specified as 30–90 min.

[0045] Furthermore, the stirring time in step S14 is 45–60 min.

[0046] Furthermore, in step S15, the centrifugation speed is 3500–8000 rpm and the time is 5–30 min.

[0047] Furthermore, in step S15, the centrifugation speed is 5000–7000 rpm and the time is 10–15 min.

[0048] Furthermore, in step S16, the mass ratio of deionized water to MXene precipitate is 5 to 10:1.

[0049] Furthermore, in step S16, the mass ratio of deionized water to MXene precipitate is 6–8:1.

[0050] Furthermore, in step S16, the centrifugation speed is 3500–8000 rpm and the time is 5–30 min.

[0051] Furthermore, in step S16, the centrifugation speed is 5000–7000 rpm and the time is 10–15 min.

[0052] Furthermore, in step S17, step S16 is repeated 2 to 8 times until the pH of the supernatant is 6 to 8.

[0053] Furthermore, step S16 is repeated 3 to 5 times in step S17 until the pH of the supernatant is 7 to 7.5.

[0054] Furthermore, in step S18, the mass ratio of deionized water to MXene precipitate is 2 to 6:1.

[0055] Furthermore, in step S18, the mass ratio of deionized water to MXene precipitate is 3 to 4:1.

[0056] Furthermore, in step S18, the centrifugation speed is 4000–8000 rpm and the time is 10–30 min.

[0057] Furthermore, in step S18, the centrifugation speed is 5500–7500 rpm and the time is 15–20 min.

[0058] Furthermore, the number of repetitions in step S18 is 1 to 4.

[0059] Furthermore, the number of repetitions in step S18 is 1 to 2.

[0060] Further specifying, (2) the operation process is as follows: after the MXene colloidal solution, PDMS basic components and additives are mixed evenly in a homogenizer, they are placed in a three-roll mill and subjected to roller pressing for 30 to 90 minutes at a speed of 150 to 250 rpm and roller spacing ratios of 100:50, 80:40, 60:30, 40:20, 20:10 and 10:5 respectively.

[0061] To further specify, the homogenizer is a non-invasive homogenizer.

[0062] Furthermore, the homogenizer speed is specified as 500–1500 rpm, and the time is specified as 40–90 s.

[0063] Furthermore, the homogenizer speed is specified as 800–1000 rpm, and the time is specified as 60–70 s.

[0064] Furthermore, the roller spacing ratios of the three-roll mill are 40:20, 20:10, and 10:5, respectively.

[0065] Furthermore, the rotational speed of the three-roll mill is 180–200 rpm, and the rolling processing time is 45–60 min.

[0066] Further specifying, (3) the operation process is as follows: add PDMS curing agent to the modified mixed solution, then homogenize and degas, pour into the mold, and place in a vacuum oven at 40-80℃ for 12-48h.

[0067] Furthermore, the heating temperature is specified as 50–60°C, and the heating time as 24–36 hours.

[0068] The third objective of this invention is to provide an application of the aforementioned lightweight, thin, wide-band underwater sound-absorbing material, specifically as an underwater sound-absorbing material adapted to small and medium-sized underwater unmanned equipment and for various marine engineering and ship equipment.

[0069] Beneficial effects:

[0070] This invention uses PDMS, which has a characteristic impedance matching that of water, as a substrate and modifies it with the two-dimensional nanomaterial MXene to prepare a thin, lightweight, and broadband underwater sound-absorbing material. The material and its sound absorption mechanism are as follows: Figure 2As shown, firstly, the abundant surface functional groups of MXene enhance the interaction with the polymer, increasing the stability of the composite structure. Secondly, utilizing the two-dimensional layered structure, high specific surface area, and excellent thermal properties of MXene, the thermoacoustic conversion, P-wave and S-wave conversion, relaxation, and damping losses of the PDMS matrix are significantly enhanced without increasing the weight of the composite material, thereby improving its underwater sound absorption performance. Compared with existing technologies, it has at least the following advantages:

[0071] (1) The thin, wideband underwater sound-absorbing material prepared by MXene modification in this invention achieves high-efficiency underwater sound absorption in a wideband range of 500 Hz to 6 kHz with a thickness of 10 mm: the sound absorption coefficient reaches above 0.86 at 1 kHz, and the sound absorption coefficient remains above 0.74 thereafter, with the highest sound absorption coefficient reaching above 0.89. The average sound absorption coefficient is 0.71 from 500 Hz to 2 kHz; and the average sound absorption coefficient is 0.83 from 2 kHz to 6 kHz.

[0072] (2) The preparation process of the thin and wide-band underwater sound-absorbing material provided by this invention is simple. It introduces equipment such as homogenizer, three-roll mill and vacuum drying oven, and the process is highly automated, which is convenient for production and promotion.

[0073] (3) The thin and wide-band underwater sound-absorbing material provided by the present invention is suitable for small and medium-sized underwater unmanned equipment. It can reduce the impact of noise as much as possible without affecting the performance of the equipment. It can also be used in various marine engineering and ship equipment to reduce the noise generated during the operation of the equipment and protect the safety of marine life. Attached Figure Description

[0074] Figure 1 This is a schematic diagram of the process for preparing the lightweight, thin, broadband underwater sound-absorbing material according to the present invention.

[0075] Figure 2 A diagram showing the thin, lightweight, wideband underwater sound-absorbing material prepared in Example 1 and its sound absorption mechanism;

[0076] Figure 3 This is a schematic diagram of an underwater sound absorption coefficient testing system.

[0077] Figure 4 Comparison of sound absorption coefficient curves for a series of thin, wideband underwater sound-absorbing materials prepared in Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2. Detailed Implementation

[0078] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0079] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art may make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0080] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0081] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0082] Example 1:

[0083] like Figure 1 As shown, the method for preparing a thin, wideband underwater sound-absorbing material in this embodiment includes the following steps:

[0084] S1: Add 4.8g of lithium fluoride powder and 60mL of 9mol / L dilute hydrochloric acid to the reaction vessel and stir at 35℃ for 1h.

[0085] S2: Add 3g of Ti3AlC2 powder to the solution obtained in step S1, and then stir at 35°C for 48h.

[0086] S3: Pour the solution from step S2 into a centrifuge tube and centrifuge at 5000 rpm for 10 min. After centrifugation, discard the supernatant and collect the precipitate.

[0087] S4: Pour the precipitate collected in step S3 into 60 mL of 2 mol / L dilute sulfuric acid and stir for 1 h.

[0088] S5: Divide the solution in the beaker into two centrifuge tubes, shake by hand for 5 minutes, then place them in a centrifuge and centrifuge at 5000 rpm for 10 minutes. Discard the supernatant and add about 30 mL of deionized water to each centrifuge tube.

[0089] S6: Repeat step S5 several times until the pH of the supernatant is 7-7.5. Then add 15 mL of deionized water to the centrifuge tube, centrifuge at 5000 rpm for 10 min, collect the upper black liquor twice to obtain the MXene colloidal solution.

[0090] S7: Add 1.92g DISPERBYK-191, 1.92g DISPERBYK-192 and 120g MXene colloidal solution sequentially to 192g Dow Corning DC184 PDMS basic components, and then stir at 900rpm for 70s in a homogenizer.

[0091] S8: Grind the well-stirred mixture from step S7 at 200 rpm in sequence according to roller spacing ratios of 40:20, 20:10, and 10:5.

[0092] S9: Add 19.2g of Dow Corning DC184 PDMS curing agent to the material ground in step S8, and then stir at 900rpm for 70s in a homogenizer.

[0093] S10: Place the fully mixed material from step S9 into a vacuum chamber and evacuate for 30 minutes. Then spray a release agent onto the mold and pour the sample into a 10mm thick mold.

[0094] S11: Place the sample obtained in step S10 into a vacuum drying oven and dry it at 60°C for 24 hours to obtain a thin, lightweight, broadband underwater sound-absorbing material based on MXene-modified polymer, such as... Figure 2 As shown.

[0095] S12: Apply the underwater sound-absorbing material obtained in step S11 to... Figure 3 The underwater sound absorption coefficient testing system shown is used to test the sound absorption performance. Specifically, the acoustic performance of the thin, wide-band underwater sound-absorbing material is tested in a water-filled standing wave tube in accordance with the industry standard CB / T 3674-2019 "Measurement Method of Standing Wave Tube for Underwater Acoustic Materials".

[0096] The sound absorption coefficient curve obtained from the test is as follows: Figure 4 As shown in the curve of Example 1, the thin, wideband underwater sound-absorbing material prepared in this example achieves high-efficiency underwater sound absorption in a wide bandwidth from 500Hz to 6kHz with a thickness of 10mm: the sound absorption coefficient reaches above 0.86 at 1kHz, and the sound absorption coefficient remains above 0.74 thereafter, with the highest sound absorption coefficient reaching above 0.89. The average sound absorption coefficient is 0.71 from 500Hz to 2kHz; and 0.83 from 2kHz to 6kHz.

[0097] The density of the obtained thin, wide-band underwater sound-absorbing material was tested and found to be 1195 kg / m³. -3 .

[0098] Example 2:

[0099] The difference between this embodiment and embodiment 1 is that the amount of MXene used in step S7 is changed to 40g, while the remaining process steps and parameter settings are the same as in embodiment 1.

[0100] The sound absorption coefficient test results are as follows Figure 4 As shown in the curve of Example 2, the sound absorption coefficient reaches more than 0.70 at 1 kHz; the average sound absorption coefficient is 0.62 from 500 Hz to 2 kHz; and the average sound absorption coefficient is 0.57 from 2 kHz to 6 kHz.

[0101] Example 3:

[0102] The difference between this embodiment and embodiment 1 is that the amount of MXene used in step S7 is changed to 80g, while the remaining process steps and parameter settings are the same as in embodiment 1.

[0103] The sound absorption coefficient test results are as follows Figure 4 As shown in the curve of Example 3, the sound absorption coefficient reaches more than 0.60 at 1 kHz; the average sound absorption coefficient is 0.70 from 500 Hz to 2 kHz; and the average sound absorption coefficient is 0.66 from 2 kHz to 6 kHz.

[0104] Comparative Example 1:

[0105] The difference between this embodiment and Embodiment 1 is that steps S1 to S6 for preparing the MXene colloidal solution are no longer performed, and DISPERBYK-191, DISPERBYK-192 and the MXene colloidal solution are no longer added in step S7. The remaining process steps and parameter settings are the same as in Embodiment 1.

[0106] The sound absorption coefficient test results are as follows Figure 4 As shown in Comparative Example 1, the sound absorption coefficient reaches over 0.50 at 1 kHz; the average sound absorption coefficient is 0.57 from 500 Hz to 2 kHz; and the average sound absorption coefficient is 0.51 from 2 kHz to 6 kHz. This indicates that the underwater sound absorption performance of pure PDMS polymer is limited, exhibiting strong resonant sound absorption performance only at specific frequencies (0.6 kHz and 6 kHz), and its overall underwater sound absorption performance is weak over a wide bandwidth.

[0107] Comparative Example 2:

[0108] The difference between this embodiment and Embodiment 1 is that: steps S1 to S6 for preparing the MXene colloidal solution are no longer performed; in step S7, MXene is no longer added, but 0.4g of carbon nanotube powder is added instead; and step S8 is not performed. The remaining process steps and parameter settings are the same as in Embodiment 1.

[0109] The sound absorption coefficient test results are as follows Figure 4As shown in Comparative Example 2, the overall sound absorption coefficient is relatively low, with only 0.08 at 1 kHz; an average sound absorption coefficient of 0.11 from 500 Hz to 2 kHz; and an average sound absorption coefficient of 0.41 from 2 kHz to 6 kHz. This indicates that the three-roll mill can effectively promote the dispersion of nanofillers in the PDMS polymer.

[0110] The above description is only a preferred embodiment of the present invention. Given that those skilled in the art can make appropriate changes and modifications to the above embodiments, the present invention is not limited to the specific embodiments described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention.

Claims

1. A light, thin, broadband underwater sound absorbing material, characterized in that, The MXene colloidal solution, the PDMS basic component and the auxiliary agent are compounded according to the mass ratio of 2-35:50:1, then the PDMS curing agent is added, and the light, thin and wide-band underwater sound-absorbing material is obtained through heating and curing.

2. The lightweight broadband underwater sound absorbing material according to claim 1, wherein, The mass ratio of the MXene colloidal solution, the PDMS basic component and the auxiliary agent is 20-30:50:

1.

3. The lightweight broadband underwater sound absorbing material of claim 1, wherein, The auxiliary agent is a wet dispersant.

4. The lightweight broadband underwater sound absorbing material according to claim 3, wherein, The auxiliary agent is DISPERBYK-191 and DISPERBYK-192.

5. The lightweight broadband underwater sound absorbing material of claim 1, wherein, The MXene colloidal solution is obtained by chemical etching of the MAX phase powder, washing and centrifuging in dilute sulfuric acid, and repeatedly washing and centrifuging in deionized water.

6. The lightweight broadband underwater sound absorbing material of claim 1, wherein, The heating and curing temperature is 40-80 DEG C.

7. A method for preparing the light, thin, broadband underwater sound absorbing material according to any one of claims 1-5, characterized in that, The method comprises the following steps: (1) preparing the MXene colloidal solution; The MAX phase powder is subjected to chemical etching, washing and centrifuging in dilute sulfuric acid after centrifugation, and repeatedly washing and centrifuging in deionized water to obtain the MXene colloidal solution; (2) adding the MXene colloidal solution to the PDMS basic component to obtain a modified mixed solution; (3) adding the PDMS curing agent to the modified mixed solution, and then heating and curing to obtain the light, thin and wide-band underwater sound-absorbing material.

8. The preparation method according to claim 7, characterized in that, The operation process of (2) is as follows: the MXene colloidal solution, the PDMS basic component and the auxiliary agent are uniformly mixed in a homogenizer, and then are subjected to roller pressing treatment in a three-roll mill at a speed of 150-250 rpm and a roller spacing ratio of 100:50, 80:40, 60:30, 40:20, 20:10 and 10:5 for 30-90 min.

9. The preparation method according to claim 7, characterized in that, The operation process of (3) is as follows: the PDMS curing agent is added to the modified mixed solution, and then is subjected to homogenization and degassing, poured into a mold, and placed in a vacuum oven for heating treatment at 40-80 DEG C for 12-48 h.

10. The use of the light, thin, broadband underwater sound absorbing material according to any one of claims 1-5, characterized in that, The light, thin and wide-band underwater sound-absorbing material is suitable for small and medium-sized underwater unmanned equipment and is used for various marine engineering and ship equipment.

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