Study On The Preparation And Mechanical Properties Of Porous Aluminum With Micron Pore Size

Porous aluminium with through-hole structure has many characteristies,such as light weight,high specific strength,energy absorption,sound absorption,filtration and high permeability.It has wide application prospects in construction,transportation,aviation,environmental management and other fields.Compared with the conventional porous aluminum with large pore size,the porous aluminum with 1-100?m pore size are highly anticipated for filtering field.At present,the minimum pore size of porous aluminium prepared by infiltration casting can only reach about 200?m,and the conventional powder metallurgy method is not suitable for the preparation of porous aluminium with micron pore size.The preparation of porous aluminium with micron pore size less than 100?m is still difficult.Therefore,a mixed powder processing method for the preparation of micron pore size porous aluminium diameter is proposed and adopted innovatively: the mixture of aluminum powder and salt is cold pressed and heated to the temperature near the liquid of aluminum,and the aluminum salt complex was prepared by the hot extrusion.Finally,the micron pore size porous aluminium with good mechanical characteristies has obtained by dissolving Na Cl in the complex.On this basis,2024 pseudo alloy powder and Na Cl powder are used as raw materials,and the micron pore size porous 2024 aluminum alloy with micron pore diameter has been successfully prepared.The main research contents include: the influence of the hot extrusion process parameters on the pore structure of micron pore size porous aluminium,the deformation ability of hot extrusion mixture,the alloying heat treatment of 2024 pseudo alloy,the influence of pore structure and alloying on the mechanical characteristies of micron pore size porous aluminium /aluminum alloy.The main results are as follows:(1)The preparation of micron pore size porous aluminium shows that when the mixing time is more than 3 h,the volume fraction of Na Cl is in the range of 50-60%,the cold pressing pressure of blank is less than 200MPa,and the hot extrusion pressure is less than 150MPa,the integrity and the uniform distribution of Na Cl particles are ensured.When the volume fraction of Na Cl between 50-60%,the hot extrusion temperature at 640-650?,the mixture has deformation ability.The optimized preparation process of micron pore size porous aluminium with uniform pore structure is as follows:the mixing time is 3h,the volume fraction of Na Cl is60%,the cold pressure is 200MPa,the hot extrusion temperature is 645?,the hot extrusion pressure is 80 MPa,the hot extrusion speed is 1.25mm/s,and the desalination rate of porous aluminum can reach 96%.(2)The research on the tensile properties of micro porous aluminum shows that the tensile failure mode of micro porous aluminum was brittle fracture.With the increase of porosity,the tensile strength and elongation decrease;With the increase of pore size,the tensile strength raise and elongation of porous aluminum with micron pore size decrease;When the pore diameter is60-80?m,the maximum tensile strength of porous aluminum with 50%porosity was 21.70MPa;When the porosity is 50%,the tensile strength of porous aluminum with a pore diameter of 20-40?m was 25.13MPa.The Gibson and octahedral mechanical models of tensile strength and porosity of porous aluminum with micro pore size are established,and the model data are basically consistent with the actual strength data.(3)The study of micro pore size porous 2024 aluminum alloy shows that after adding Cu,Mg,Si,Mn and other elements into the mixed powder to form porous 2024 pseudo alloy,the alloy is carried out at 490 ?,which makes the diffusion reaction of Al,Cu and other elements under high temperature by formed Cu Al2 and complete the alloying,the mechanical property was further improved.Compared with porous aluminum with the same conditions,the tensile strength of porous 2024 aluminum alloy with a pore diameter of 20-40 ?m and a porosity of 50 % is increased from 25.13 MPa to 29.16 MPa.Through the above research,micron pore size porous aluminum/aluminium alloy with porosity of 50-60% and pore size of 20-80?m was successfully obtained.The preparation and mechanical properties of micron pore size porous aluminium/aluminium alloy were preliminarily formed,which laid a foundation for further research and development of micron pore size porous aluminium.