Effect of mechanical stirrer on graphite particles and SiC_P in C-SiC/Cu semi-solid slurry

The mechanical stirring of C-SiC/Cu semi-solid slurry was conducted in a cylindrical crucible by a straight-blade stirrer. The distribution of graphite particles and SiC particles (SiC_P) in the C-SiC/Cu semi-solid slurry was studied under 200 r/min for stirring speed and 10 mm/s for speed of moving up and down of stirrer. The results show that there is a quadratic relationship between the angle γ between the straight blade and the horizontal plane and the content of the graphite particles and SiC_P in the top and bottom of the crucible. When γ=30°, the axial distributions in the crucible of graphite particles and SiC_P are homogeneous, but the SiC_P are still segregated, which indicates that the segregation of SiC_P leads to the unhomogeneity of C-SiC/Cu semi-solid slurry in conventional straight-blade mechanical stirring. The double-blade agitator is used instead of the conventional straight blade agitator to adjust the blade layer spacing h to 10–20 mm, which can eliminate the segregation of SiC_P. The wear tests of the C-SiC/Cu composites obtained by mechanical stirring casting with single blade stirrer and double-layer blade stirrer were carried out. The wear rates of different parts of C-SiC/Cu composites in the single blade mechanical stirring casting are different, however, they are nearly the same in the double-layer blade. It shows that the segregation of SiC_P can be eliminated by increasing the mechanical agitation shearing action. The uniform distribution of C-SiC/Cu semi-solid slurry can be achieved by double-layer-stirrer mechanical stirring.