Open Cell Aluminum Foam Fabricated By Gypsum Investment Casting

Open cell aluminum foam is a “sponge” like porous metal with three-dimensional connected.As a good energy buffer material,its anisotropic structure ensures that the gas can escape quickly when passing through,deform quickly when compressed,and reduce potential rebound effect.In this paper,the effects of gypsum composition on the performance of the prefabricated body and the effects of seepage temperature,pressure and size of the seepage channel on the seepage length during the seepage process are studied in view of the imperfections of the present preparation process of the porous aluminum foam,and the optimal process route is determined.At the same time,the structure and mechanical properties of the aluminum foam were characterized.In view of the existing problems of gypsum investment casting,the composition of gypsum slurry,including hemihydrate gypsum,water,refractory filler,retarder and other types and the effect of addition amount on gypsum performance were studied.In this paper,the properties of gypsum for the preparation of porous aluminum foam by investment casting were optimized,and a gypsum formula to meet the specific requirements was obtained.The initial setting time is 18 minutes formula gypsum slurry,final set time of 44 minutes,flow radius of 110 mm,wet strength is 1.62 MP,wet strength is 1.62 MPa,dry strength is 3.58 MPa,gypsum breakup rate was 15%?18%,the crack tendency to ?.It can meet the performance requirement of gypsum mold investment casting for aluminum foam gypsum prefabrication.The semi-symmetric hexahedron model is established to qualitatively analyze the three seepage technological parameters: seepage temperature,seepage pressure and seepage channel size.The seepage process model can describe the influence of temperature,pressure and channel size on the integrity of seepage,and explain the cause of defects.All these provide theoretical guidance for the optimization of the technology of producing aluminum foam by investment casting.10 PPI?50 PPI ultra-light open cell aluminum foam was fabricated successfully by gypsum investment casting combined with pressure filtration,the relative density of aluminum foam at about 2%,pore structure,split hole foam aluminum substrate material compression,can affect the performance of absorption,with the increase of the foam aluminum pore density,average pore diameter decreases,porosity change is not big,the thickest 10 PPI ligament,the change of pore structure will affect the mechanical properties.The compressive properties of aluminum sponge are different with different matrix materials.Alloying to a certain extent will enhance the compression platform,improve the compression performance of aluminum foam.Different pore densities will affect the compression performance of aluminum sponge,10/20 PPI,30/40 PPI similar compression performance,the main factor affecting the stress platform is the average pore size.The subsequence of the energy absorption and ideal energy absorption efficiency are 20 PPI>30PPI>10 PPI>40 PPI,20 PPI>30 PPI>40 PPI>10 PPI respectively.