Abstract
The preparation of porous aluminum by die casting was investigated in this work, including both the 〝lost foam 〞method and the〝ceramic ball preform 〞method. In the lost foam die casting method, we utilized the swelling phenomenon caused by soaking the polymer foam in a proper organic solution to increase the ligament thickness and its porosity. As a result, the ligament thickness and porosity of finished products can be easily tailored. Using different polymer foams from various suppliers, we can make porous aluminums whose ligament thickness is in the range of 0.117?0.458mm and porosity about 90?95%.In the ceramic ball preform method, we found a special formula（weight ratio of Al2O3：bentonite：HPMC：water：PVA is 100：1：2：48.3：2.4） for making ceramic balls with sufficient strength to survive the casting procedures. These ceramic balls of several mm in size, can be easily removed from the finished products by high pressure water after casting. One of the ingenuity of this procedure lies in the fact that these ceramic balls are soft and deformable at room temperature. For this reason, we can apply pressure to increase the compactness of the packed bed made of these ceramic balls. As a result, the porosity the finished products can be substantially increased. On the other hand, the uniformity of the product can be improved if regular packing technique was employed rather than the random packing method. On the average, the porosity of the product is in the range of 80?89%.