| Porous metal materials has a dual characteristic of metal and pore,so they have unique properties that dense metal and other porous materials do not have,such as light weight,high specific strength,high stiffness,good energy absorption performance,vibration isolation,noise elimination,etc.Because aluminum,magnesium and its alloys have advantages of low density,high specific strength,and good casting performance,they become the focus of the porous metal materials.Aimed to the specific requirements of the porous materials on noise reduction and vibration isolation,porous aluminum and magnesium materials with spherical pore and aluminum-perlite porous composites and their sandwich structures have been prepared by vacuum seepage flow casting used spherical salt pill and natural expanded perlite as prefabricated body.Structure,mechanical properties,acoustic performance and energy absorption performance,interface properties of porous materials and components have been studied with a variety of characterization and testing methods,such as SEM,TEM compression,pooling and acoustic tests,etc.Research job is mainly focused on two contents.One is influence and mechanism of the pore wall material,pore diameter,relative density on mechanics energy absorption,sound absorption performance of porous materials.The other is that the design,manufacture,test and evaluation of materials and devices according to special demand for vibration isolation and noise elimination.Detailed experimental results are as follows:1.The preparation technology of series of salt pill was invented and controllable preparation technology of spherical porous aluminum and magnesium was realized.It is successfully achieved small deformation,uniform and large size aluminum-perlite porous composite sheet.Sandwich beams were prepared by vacuum filtration method and they have spherical porous aluminum or aluminum-perlite porous composite material as inner core and steel as skin.Aqueous gel material was in situ synthesized in the spherical pore of sandwich.The two sandwich components are abbreviated perlite-sandwich and gel-sandwich.2.The results of compression tests of spherical porous aluminum and magnesium and aluminum-perlite porous composite showed that material inhomogeneity leads to pore-wall bending deformation and material failure destruction.The influences on the compression performance of the porous materials are that pore-wall material is the most significant,relative density is more significant and aperture or particle size is the smallest.Elements alloying and heat treatment on the pore-wall material can significantly improve the porous material yield stress,plateau stress,energy absorption performance and efficient.The porous material with greater relative density has higher yield and plateau stress and energy absorption performance.3.Sandwich component interface have been studied and the results show that Mg and RE alloying elements addition can significantly improve the interface organization morphology and improve the metallurgical bonding performance.4.The sound absorption performance of spherical porous aluminum samples are impact to thickness,pore diameter and porosity.The porosity is the most remarkable influence factor and its variation is change of connected pore diameter in essence.The main absorption mechanism of spherical porous aluminum is viscous effect of special pore structure on acoustic wave propagation.5.Spherical porous aluminum material has been designed,trial produced and applied to noise elimination component of high-pressure silencer of special ship.The bench test results show that spherical porous aluminum material has a good noise elimination performance and good air permeability.The combination use of spherical porous aluminum and porous nickel has better noise elimination and air permeability than currently used material and can avoid disadvantage of low-temperature condensation and silencing failure of currently used material.Porous diffusion effect is the main noise elimination mechanism.6.Sandwich beams are used vibration isolation components and patch test is carried out on a high-power fan.The results show that the perlite-sandwich beam and gel-sandwich beam have better performance of vibration isolation.Especially,gel-sandwich beams have similar vibration isolation performance of original rubber vibration isolator and integrated vibration value of 0-5KHz spectrum is lower than that of original rubber vibration isolator.7.Used on high speed centrifuge tests show that vibration intensity of X,Y,Z three directions significantly decreases on the centrifuge and chassis when sandwich beam component replace to rubber material,and show that it has good vibration isolation and damping.8.It is mainly mechanism of vibration isolation and reduction in sandwich beam that internal porous structure is benefit to vibration energy transfer and spread,and mechanical vibration can be effectively converted into heat energy by pore-wall interface friction with perlite or gel,which increases the viscous damping coefficient C value.In the gel-sandwich beam,the polymer network structure easier to vibration energy transfer and dissipation. |
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