Analysis of the sound absorption performance of metal foam and its influencing factors
Core Tip: Metal foam is a new type of porous material. The metal of foam has the characteristics of continuous phase metal such as high strength, good thermal conductivity, high temperature resistance and characteristics of dispersed phase pores such as damping, isolation, insulation and noise reduction. Seismic and other organically combined. Today, China's thermal insulation network prototype for everyone to organize the sound absorption properties of metal foam and its influencing factors.
Metal foam is a new type of porous material. After foaming treatment, a large number of bubbles are formed inside the foam. These bubbles are distributed in a continuous metal phase to form a pore structure, which makes the metal of the continuous phase such as high strength and thermal conductivity. The high temperature resistance and the like are combined with the characteristics of the dispersed phase pores such as damping, isolation, insulation, and sound absorbing and shock absorbing. At the same time, the metal foam also has good electromagnetic shielding and corrosion resistance. At present, metal foam research has been greatly developed. The metals involved include Al, Ni, Cu, Mg, etc. The most studied ones are aluminum foam and its alloys.
Today, the insulation network prototype for everyone to organize the sound absorption properties of metal foam and its influencing factors.
Sound absorption properties of metal foam and its influencing factors
The irregularity of the bubble in the metal foam and its three-dimensional uniformity produce excellent sound absorption characteristics, and have many advantages compared with glass wool and asbestos. It is a foam composed of a metal skeleton and air bubbles. It has a rigid structure and good processing performance, and can be made into various forms of sound absorbing panels; it is non-hygroscopic and easy to clean, and the sound absorption performance is not reduced; It may be damaged or dusted by wind pressure; it can withstand high temperatures, will not catch fire and release poison gas. The metal foam also has good sound absorption performance not only in the high frequency region but also in the middle and low frequency regions.
The sound absorption properties of metal foam are affected by many factors, such as the uniformity of pore distribution, the size of pores and porosity, and the thickness of foam. Taking foamed aluminum as an example, for foam aluminum samples of different structural sizes, the change of sound absorption coefficient in the same frequency band is irregular, and some frequency bands are large aperture high, and some frequency bands are small aperture high, and the void ratio changes. After that, the sound absorption coefficient changes irregularly in the same frequency band. However, from the comprehensive effect, the sound absorption performance of aluminum foam still has strong structural sensitivity. With the uniform distribution of pores, the decrease of pore size and the increase of void ratio, the comprehensive sound absorption coefficient of each frequency band of the sample is There is an increasing trend, and as the thickness of the sample increases, the frequency range in which sound absorption is better expands toward the low frequency direction. Some people in China have studied the underwater acoustic absorption characteristics and influencing factors of aluminum foam. It is found that foam aluminum has good underwater acoustic absorption performance, and the effects of pore size, porosity and thickness on sound absorption performance are analyzed. Foam aluminum has been successfully applied to the sound absorption field of air compressor room, train engine room, audio room, construction site, etc., and has achieved good results.