Study On Preparation Technology Of Foil Aluminum And Its Composite Structure

Aluminum foam is a new type of metal materials with a large number of pore structure in the matrix. Because of the unique pore in its internal structure, it is possible to obtain many excellent properties, such as energy absorption, thermal insulation, high specific strength and shock absorption, etc. And by using the aluminum foam as sandwich layer of composite structure product, it overcomes the disadvantages of low strength and significantly boosts mechanical properties. Therefore, composite structure product broadens its application scope and becomes the hotspot of metal material study. In view of aluminum foam with closed pore, powder compaction metallurgy method(PCM) is the most commonly used method and has advantages over other methods.By using PCM method on the basis of previous studies, this study mainly focused on the influence of Mg powder adding amount, Mg powder granularity and mixing time on the pore structure of aluminum foam. Moreover, the preparation technology of aluminum foam was optimized through profound comparative study of the effect of process parameters(heating rate, sample temperature) on pore structure of aluminum foam. Besides, three kinds of preparation methods to acquire the composite structure of aluminum foam were studied.The experimental results indicate that:(1) When other condition is constant, Mg powder adding amount, Mg powder granularity and mixing time exert substantial impact on the pore structure of aluminum foam, the ranking of relative importance of influential factors are as follows:Mg powder granularity, mixing time and Mg powder adding amount. And the optimal parameters are: mixing time of 60 min, Mg powder adding amount of 0.6 wt % and Mg powder granularity of 325 mesh size.(2) Heating rate and foaming temperature exert great effect on the pore structure and foaming expansion of aluminum foam. Under the experimental condition, it is concluded that the best preset temperature is 800℃, the temperature of tested specimens is ranging from 680 to 770℃ ℃. In this scope of condition, aluminum foam is obtained with porosity range from 50% to 75%, the average pore diameter range from 3.1 mm to 4.2 mm and the average roundness range from 0.45 to 0.66. When the sample reaches maximum expansion value(about temperature of 750℃), it begins to collapse(around collapse temperature of 770℃).(3) Three combination methods for preparation of composite structure of aluminum foam(such as adhesion method, hot compression method and self-propagating method) are studied. Among these, both adhesion method and hot compression method can achieve the combination of steel sheet and aluminum foam core in aluminum foam composite structure. In preparation process of self-propagating, the interfacial combination is not achieved due to the ratio of raw materials and process problems. By comparison with compression tests and microscopic analysis of interface, it is revealed that the aluminum foam composite structure which is produced by hot compression method is more effective in interfacial combination than the aluminum foam composite structure which is produced by adhesion method. On the other hand, its mechanical properties are also improved.