Preparation Of Foam Aluminum By Melt Foaming And Its Pore Structureturn

Foam aluminum,as a kind of metal foam material it is widely used both domestically and internationally due to its inherent characteristics of metals,as well as its advantages such as high porosity,large specific surface area,and high strength and other advantages.At the same time,because of its sound absorption,sound insulation and damping performance,widely used in fields such as construction,aviation,and transportation.There are many methods to prepare foam aluminum,including melt foaming method,infiltration casting method,powder compaction melting method and investment casting method.Due to the problems of uneven pore structure and poor process stability in the production and research and development of foam aluminum in China,in order to prepare foam aluminum samples with uniform pore structure and few defects and realize the development of foam aluminum industry towards large-scale and high-performance,this time,the molten foaming method is used to complete the preparation of foam aluminum.The base material is industrial pure aluminum,Ti H₂is the foaming agent,the purity is 97%,and the metal calcium particles with a diameter of 1～3 mm are used as the tackifier.（1）Process research:four factors and three levels orthogonal test were used to analyze the pore structure characteristics of foam aluminum prepared by different variables.Use range analysis method to analyze and process the orthogonal experiment with four factors and three levels,and obtain a set of optimal factor level combinations.Compared with the sample with uniform pore structure in the orthogonal experiment,the optimal factor level combination of range analysis method is the optimal parameter for foam aluminum preparation,that is,the optimal parameter is 3%Ca addition,720℃Ca mixing temperature,6 min Ca mixing time,700 r/min Ca mixing speed,1.5%Ti H₂addition,670℃Ti H₂mixing temperature,3 min Ti H₂mixing time,800 r/min Ti H₂mixing speed,690℃holding temperature,and 5 min holding time.At the same time,the biggest factor influencing the pore structure and porosity of foam aluminum among the four variables is the amount of Ca added.（2）Process optimization:In the pre-treatment process of foaming agent（titanium hydride）,in addition to traditional oxidation treatment,the ball milling method is also used to mix the pre oxidized titanium hydride powder with copper powder in equal proportions and add it as a foaming agent to the melt,making the titanium hydride particles more easily dispersed and reducing particle aggregation in the melt.In the optimization test,the first stage optimal process parameters were used to prepare foam.Analyze the pore structure of foam aluminum samples prepared in two stages,use Image-J software to calculate the average pore diameter,roundness,etc.,and calculate the porosity of foam aluminum by measuring the volume of foam aluminum.The results show that the pore size of foam aluminum with copper powder decreases,the roundness increases,and the porosity increases,and the pore structure is better than that of foam aluminum without copper powder.The experimental results showed that the pore structure of foam aluminum was further optimized,and the foam aluminum with porosity of 83.2%,average pore diameter of 1.9 mm and roundness of 0.79 was prepared.（3）Performance research:compression experiments were carried out on foam aluminum,and the optimal samples of foam aluminum pore structure prepared by orthogonal experiments and optimization experiments were selected for compression experiments.Finally,it is concluded that the compression performance of foam aluminum sample with copper powder is better than that of foam aluminum sample without copper powder because it improves the uniformity of pore structure.