Studies On Fabrication And Properties Of ZA22/SiC_p Composite Foams

The metal foams are kinds of structural and functional materials. Recently, the researches about metal foams are very active. It is not only a part of porous materials, but also a hot point in the field of the development of new material. Zn-Al alloy foams and Zn-Al alloy composite foams have good mechanical properties and high damping ability. Currently, only a small amount of researches for the quasi-static and dynamic mechanical properties of ZA22 foams were carried out, and the effects of rare earth elements on the structures and damping properties of ZA22 foams were studied. It was not reported that the research of SiC particle reinforced Zn-Al composite close foams and the relationship between SiCp and ZA22/SiCp composite foams. Researching on the Zn-Al alloy foams and SiC particle reinforced composite foams will broaden the field of metal foams production and application. Based on the insufficiencies of the researches on SiC particle reinforced Zn-Al composite foams, the following researches were carried out in this dissertation:Firstly, SiC particle reinforced ZA22 composite foams were successfully fabricated by the direct foaming of the melt with CaCO3 for blowing agent. The effects of the foaming temperature on the fabrication of foams were systemically analyzed.Secondly, through test quasi-static and dynamic compression, the effects of SiC particle size and volume fraction on the mechanical properties of ZA22/SiCp composite foams were firstly performed. The results show that in the process of compression, the strain-stress curve of ZA22/SiCp composite foams was the same as ZA22 foams. It contains three distinct stages: elastic stage, plastic platform stage and dense stage. However, the addition of SiCp changes the original deformation mechanism. The mechanical response is more complex, and the platform has a big fluctuation. Because of the role of stress concentration, the stress-strain curve appears obvious stress peak. Whether a static load or dynamic load, the yield stress and the energy absorption of ZA22/SiCp composite foams increase with increasing the relative density and volume fraction of SiC particle and decreasing the size of SiC particles. The yield stress and platform stress increase with increasing strain rate under dynamic load. This paper also establishes the relationship between relative stress and relative density in the static load, and the experimental results are consistent with Gibson and Ashby model.Finally, the damping property of ZA22/SiCp composite foams at room temperature is better than that of ZA22 foams. The reason is the contribution of the interfaces between SiCp and matrix material and the high density dislocation. The loss factor of ZA22/SiCp composite foams increases with the decrease of relative density and size of SiCp and the increase of volume fraction of SiCp.