Preparation And Compressive Properties Of Sponge Aluminum By Investment Casting

Open cell aluminum foam with sponge structure(also called aluminum sponge)has important application potential in weight reduction,energy absorption,shock absorption,sound absorption,electromagnetic shielding,thermal management and other fields.Aluminum sponge also has some shortcomings in engineering application,such as low compression performance as an energy absorbing material;In addition,the mass production of large-scale aluminum sponge materials is still unable to be realized.In view of these two problems,this thesis systematically studied the gypsum casting method of aluminum sponge material.The mechanical properties of porous gypsum were improved by optimizing gypsum composition,and the mechanical properties of aluminum sponge were improved by increasing the struct of polyurethane sponge.Finally,the preparation technology of large-size aluminum sponge is explored.Firstly,the effects of water solid ratio,filler type and content,water reducing agent content and collapsing agent content on the gelation time,fluidity,bending strength,thermal shock resistance and linear shrinkage of gypsum slurry were studied.Finally,a gypsum formula which can be used for aluminum sponge investment casting was obtained.The struct thickening process of polyurethane sponge matrix was studied.Among them,the thickness of 10 PPI sponge struct increased from 0.401 mm to 1.052 mm;the thickness of 20 PPI sponge struct increased from 0.231 mm to 0.573 m.The preparation process of aluminum sponge structure by gas pressure infiltration and solid pressure infiltration was studied.The gas pressure infiltration is easy to realize the preparation of small-size and defect-free aluminum sponge,while the solid pressure infiltration can realize the preparation of large-size aluminum sponge.In this thesis,the process parameters of solid pressure infiltration method were optimized,and the preparation of large-size aluminum sponge was realized,and the causes of defects were analyzed.Finally,aluminum sponge structures with different struct size and different pore density(10ppi and 20ppi)were prepared,and the effects of matrix material and struct thickening(relative density)on the compressive properties of aluminum sponge were systematically studied.