304不锈钢纤维/ZL104铝合金复合泡沫的孔结构、力学、吸声性能及其机理

Pore Structure,Mechanical and Sound Absorption Performance for Composite Foam of 304 Stainless Steel Fiber/ZL104 Aluminum Alloy

用渗流铸造法制备ZL104合金泡沫和304不锈钢纤维/ZL104合金复合泡沫,对比研究了两种泡沫的孔结构、力学和吸声性能及其机理。结果表明,调控盐(次盐)的作用使合金泡沫和复合泡沫的孔壁上出现次孔结构而生成多孔孔壁结构;纤维复合后的泡沫以孔壁纤维、穿孔纤维和孔间纤维三种状态存在,与相同孔隙率的合金泡沫相比,复合泡沫的孔隙率为77%~86%、主孔径为0.35 mm、纤维直径为0.1 mm,具有更高的压缩性能和吸声性能。复合泡沫的压缩性能和吸声性能,都随着孔隙率和纤维含量的提高先提高后降低。孔隙率为82%的复合泡沫,纤维含量(体积分数)为5%时力学性能达到2.6 MPa,纤维含量为8%时其平均吸声系数(吸声性能)为0.893。有限元分析结果表明,复合泡沫受力时,孔壁纤维和穿孔纤维能传递和分散应力,并通过位移和偏转等方式消耗能量,使其强度提高;J-A模型分析结果表明,突出到孔隙中的纤维使复合泡沫的表面粗糙度和比表面积和声波在泡沫内的损耗增大,是其吸声性能较高的原因。

Foam materials of ZL104 alloy and 304 stainless steel fiber/ZL104 alloy composite were prepared by the infiltration casting method,and their pore structure,mechanical performance,sound absorption properties and the relevant mechanisms were investigated.The results show that within the prepared foam materials,there exist interconnected larger pores,and on the wall of which,there are many smaller sub-pores.The formation of such sub-porous structure may be ascribed to the effect of the second moderating salt adopted for the infiltration casting.Moreover,the fibers present in three states in the composite foam:pore wall fiber,perforated fiber,and inter-porous fiber.The typical composite foam with fiber diameter of 0.1 mm and porosity of 77-86%,while the mean diameter of 0.35mm for the main pores.The composite foam has better compression yield strength and sound absorption performance rather that those of the alloy foam with the same porosity.The compression and sound absorption properties of composite foams increased first and then decreased with the increasing porosity and fiber content.It is wealthy noted that among others the compression yield strength reaching the peak value of 2.6 MPa for the foam with porosity of 82%and fiber content of 5%,accordingly,the average sound absorption coefficient reaching the peak value 0.893 for the composite foam with porosity of 82%and fiber content of 8%,respectively.Finite element analysis shows that when being pressed,the pore wall fibers and perforated fibers can transfer and disperse stress,and the energy can be consumed by displacement and deflection of the fibers,thus enhancing the strength of the composite foam.J-A model analysis shows that the fibers protruded into the pores increase the surface roughness and specific surface area of the foam,resulting in an increasing acoustic wave loss of the composite foam,which is the reason for the higher sound absorption property of the composite foam.