Study On Preparation And Mechanical Properties Of Aluminum Foam Composite Structure

Foamed aluminum composite structure is a composite material in which the porous foam core material and the dense shell are combined with a certain connection method.It has not only foam core of light material,impact resistance,vibration damping and other characteristics,but also a dense shell of high strength.So that has a very considerable application prospects in people's livelihood,defense,aerospace and other fields.At present,the preparation of composite structure is numerous,but most of the preparation process is complicated and the cost of mold is high.Especially for some large and complex components,the existing composite process is difficult to get filling effect better and uniform the core porosity.In this paper,the integration process(foaming process and filling process)of the traditional powder compaction foaming method(PCF method)were separated and studied,The advanced pore morphology(APM)foam were first prepared by the foaming process,followed by filling it into the tubes.In order to assess the performance of tubes,the samples were prepared by this method.The basic parameters of the composite structure preparation process were obtained by experiment,and the foaming and bonding mechanism were analyzed.The mechanical properties of the composite structures obtained by this method were tested and compared with the mechanical properties of the hollow molds.The results were shown as below:1)As the foaming stage,The preparation of the preform by the hot extrusion process can significantly enhance the foaming effect.When the furnace temperature is above 780 ?,it can accelerate the process of Al-Si alloying.The heating speed and foaming time have a great influence on the parameters and pore structure of the sample.When the heating rate is 2.6 ? / s,the effect of foaming is best.The pore structure is uniform and the spherical shape of APM is higher when the foaming process is close to the maximum point of expansion.The type of foaming agent will have some influence on the expansion parameters,the time of reaching platform,length of area and temperature of reaching the maximum expansion point with ZrH2 as foam agent are more than TiH2.2)As the filling stage,Adhesive and epoxy foaming were used to fill thin-walled steel tubes with APM.When the bonding process is carried out by epoxy adhesive process,the APM still maintain the in-situ filling state,and the filling uniformity is only related to theinitial filling rate.When the epoxy foaming process is used for filling,filling APM with 15 mm diameter is better than the diameter of 20 mm.When the filling rate of APM is 80% and100%,the uniformity of arrangement in the tube is better than 50% and 30%.As for large sized special-shaped mold,when using APM with diameter of 15 mm and the filling rate of100%,the results is best.And the APM filling method improves the average circularity of the foam holes in mold,and enhances the uniformity and reproducibility of the pore structure.3)Two kinds of composite pipe samples were prepared by epoxy adhesive and epoxy foaming.The APM pellets,thin-walled air tubes and composite pipe were quasi-static compressed.The results showed that APM were close to the two sides of worktable collapse first,and then extended to the central part until all crushed.The stress-load curve of the APM is roughly the same as the traditional foam aluminum,the platform area is larger.The thin-walled steel tube is mainly asymmetrical deformation mode,Adhesive-APM filled tube is mixed mode,Epoxy foamed-APM filled tube shows a typical hexagonal deformation mode.The latter two number of folds are more than thin-walled tube.Adhesive-APM filled tube and Epoxy foamed-APM improve the level of compression load.The ideal energy absorption efficiency of the epoxy foam-APM composite pipe is about 188% of the thin-walled tube,up to 113% of the epoxy adhesive-APM composite tubes.