Research On Noise Reduction And Heat Insulation Performance Of Multilayer Composites Based On Aerogel

The vibration and noise of equipment can affect its accuracy,lifespan,and the health of operators.The use of protective covers for equipment can effectively solve these problems.However,traditional protective materials often only focus on either insulation or noise reduction performance,and there are disadvantages such as high cost,large size,and thickness.For example,silica aerogel has the characteristics of high specific surface area,low density,and low acoustic impedance,which are widely used in both noise reduction and insulation applications.However,aerogel composite materials also have many disadvantages,such as poor mechanical properties,easy generation of dust,and moisture susceptibility,which greatly limits its application.In this article,a composite material with both soundproofing and insulation properties is prepared using a silica aerogel/fiberglass material as the base and using foam polyurethane and carbon fiber porous material as the reinforcing agent.The effects of stacking method and reinforcing agent thickness ratio on the performance of composite materials are discussed.First,a series of polyurethane/aerogel multi-layer composite material samples with different foam polyurethane component ratios were prepared by adjusting the stacking amount of foam polyurethane using the stacking method with silica aerogel/fiberglass as the base material.The effects of foam polyurethane component ratio and stacking method on the soundproofing and insulation properties of composite materials were explored.The sound insulation performance of the composite material was evaluated using sound impedance tubes,with sound insulation,average sound insulation,sound absorption coefficient,and average sound absorption coefficient as evaluation standards.The insulation performance of the composite material was tested using a constant temperature electric hot plate,with the temperature of the top layer of the composite material and the time used to reach heat dissipation balance as evaluation standards.The results showed that the sound insulation performance of the composite material was best when the foam polyurethane thickness ratio was 1/3 and the foam polyurethane was located in the second layer.Changing the stacking method did not have a significant impact on the overall resonance frequency point of the material,but mainly affected the absorption of sound waves in the 500～6300 Hz frequency range.Compared with silica aerogel alone,the composite with foam polyurethane could improve the sound insulation performance of silica aerogel in the mid-to-high frequency range,but it would reduce the sound insulation effect in the 63～500 Hz range.The higher the foam polyurethane thickness ratio,the better the overall sound absorption performance of the composite material.When the foam polyurethane thickness ratio was 1/3 and the foam polyurethane layer was located at the bottom of the stacked composite material,the insulation performance of the composite material was the best.Then,using silica aerogel/fiberglass as the substrate and a stacking method,multi-layered carbon fiber aerogel composite materials with different carbon fiber component ratios were prepared by adjusting the amount of carbon fiber,in order to explore the influence of carbon fiber component ratios and stacking methods on the sound insulation and thermal insulation performance of the composite materials.The acoustic performance was characterized using an acoustic impedance tube,with sound insulation amount,average sound insulation amount,sound absorption coefficient,and average sound absorption coefficient as evaluation criteria for the noise reduction performance of the composite materials.The thermal insulation performance was tested using a constant temperature electric heating plate,with the uppermost temperature of the composite material and the time used to achieve heat dissipation equilibrium as evaluation criteria for the thermal insulation performance of the composite materials.The results showed that changing the stacking method would affect the resonance points of the composite materials in the range of 67～500 Hz,and as the thickness ratio increased,the sound insulation performance in the low-frequency range would also decrease,but the sound insulation performance in the range of 500～6300 Hz was similar to that of single silica aerogel tested results.With the increase of the carbon fiber component ratio in the composite material,the sound insulation performance of the material in the range of 67～6300 Hz first increased and then decreased.The sound absorption performance parameters of the composite material after the combination of silica aerogel and carbon fiber were between the sound absorption test results of the two materials used separately,and the higher the thickness ratio of carbon fiber in the composite material,the higher the sound absorption coefficient of the composite material.The higher the carbon fiber thickness ratio,the better the thermal insulation performance of the composite material.