Using liquid homogenization in order to produce Al-Gr composite with SPS and cold pressed-sintered in furnace and investigation of microstructure

To produce aluminum matrix composite reinforced with graphite particles, mixing of pure aluminum and graphite powders by a new method, called homogenization in liquid phase, was performed. The graphite content was chosen from zero to 4.5wt.%. First, the graphite powder was poured into acetone, and was mixed by ultrasonic. The aluminum powder was added to the solution and ultrasonic was continued. Then the filtered mixture was dried in vacuum, with suitable temperature and time. Composite samples were produced using the dried powder by two ways: spark plasma sintering (SPS) and cold pressing and thereafter sintering in a vacuum furnace under different pressure, temperature and time. The microstructure was investigated by OM and SEM. To calculate the porosity and density of the samples the Archimedes method was used. Brinell hardness test were used. Compared to other methods, using this method caused significant improvement in the distribution of graphite particles in the matrix and finally the increasing the hardness .The optimum wt.% of graphite to distribute uniformly in the aluminum matrix and to obtain the highest hardness and lowest prosity was 3wt.%.