Preparation of Al₂O₃/Cu porous composites by combination of solution combustion synthesis and powder metallurgy method

Al₂O₃/Cu composite powders were prepared by solution combustion synthesis and hydrogen reduction method using copper nitrate, aluminum nitrate, glucose, and urea as the raw materials. The Al₂O₃/Cu composite powders were uniformly mixed with the pore-forming agent sodium chloride, and then the mixed powders were cold-pressed. Finally, the Al₂O₃/Cu porous composite materials (A-C-M) were prepared by sintering-dissolution process. The raw powders and A-C-M were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The compression performance of A-C-M was tested by universal testing machine. The effect of glucose addition on the combustion product powders was studied. The effect of Al₂O₃ content on the compression performance of A-C-M was discussed. The results show that, when the molar ratio of glucose to Cu(NO₃)₂ is 1, the specific surface area of the combustion products reaches the maximum as 12.5 m²·g^‒1. After the combustion product is calcined to remove carbon, the pores of the powder particles increase, but the specific surface area is reduced to 10.2 m²·g^‒1 due to the sintering effect of high temperature calcination. After the calcination products are reduced by hydrogen, the powder particles are broken into floccules. However, due to the sintering effect of high reduction temperature, the specific surface area of the obtained Al₂O₃/Cu composite powders is further reduced to 7.5 m²·g^‒1. With the increase of Al₂O₃ content, the porosity of A-C-M increases gradually, and the compressive strength decreases gradually.