Preparation And Reliability Evalution Of The Aluminum Foam Sandwich

Aluminum Foam Sandwich, with foam aluminum as the core layer, metal forthe panel, is a new type of structural materials, which has a series of excellentperformance, in the automotive, aerospace and construction and other fields hasbeen widely applied. The foundation of the application is the realization of effectiveconnection between foam aluminum and metal plate, but the surface porous andoxidation film makes foam aluminum connection problems. Aiming at this problem,this paper puts forward the scratching and vibration auxiliary brazing method, withZn-Al-Cu alloy for solder. Then using the above methods, prepared the sandwichstructure well connected, and has carried on these compressive, bending and impactperformance test and analysis.Scratching and vibration auxiliary soldering, the specific process as follows:heat the mother material surface by flame, melt the solder and scratch at the sametime; after cooling, dock the aluminum foams and two aluminum panel up and down,then secondary heating; the secondary cooling is applied in the process of vibrationeffect, completely after cooling to obtain structural sandwich panel. In the secondcooling stage, without vibration effect, putting on mechanical vibration and theultrasonic vibration is applied to get connection interfaces of different structuralsandwich panel.Mechanical scraping, contribute to the removal of the surface oxide film,forming a capillary channel, so that the wetting and spreading smoothly. Jointbetween aluminum sheet and aluminum foam, solder combine with aluminum sheettight, only connect with the aluminum foam hole wall surface. The second coolingstage without vibration, solder fill into the aluminum foam pore; putting onmechanical vibration, solder flow and fill into the pores but fill uneven; ultrasonicvibration, solder flow and filled into the pores and uniform filling.The joint of prepared sandwich plate, solder/aluminum and solder/aluminumfoam hole wall surface combination formed the microstructure organization by fourphase composition, while the center solder by three phase composition. The secondcooling stage exert different effects are similar to the interface microstructure, phasecomposition of different. Tensile shear test results show that the aluminum sheetwell connect with aluminum foam from the beginning to the end.Aluminum foam and the prepared sandwich structure plate, the stress straincurve corresponding to compression tests can be divided into three stages: elastic,stress platform and densification stage; slope of the energy absorbing strain curveincreases gradually, show that the energy absorption efficiency raise. The prepared sandwich panel of three point bending test, stress-strain curve is composed of threestages, which consists of a panel of local buckling, core shear failure and paneldepressions and core layer compacting process to explain. In three point bendingand impact test, the sandwich panel show than the aluminum foam is more excellentperformance, strength and energy absorption of foam aluminum is several times oreven several times. After the test, integral sandwich structure does not fracture, butcore layer is destroyed serious and the interface connection is still tight.The wetting behavior of porous surface of aluminum foam affected by thesurface state, solder composition, porosity (wall thickness) and other factors. ForZn-Al-Cu alloy wetting on aluminum foam surface, the paper build down "concave"shape of the wetting model and carry out the preliminary calculation.