Erosion Characteristics of Aluminum-based Metal Matrix Composites in Slurry Environments

The erosion resistance of the Al18B4O33 whisker reinforced AC4C Al composites in water and saline slurry were investigated using a jet-in-slit rig. Erosion tests were performed at slurry velocities between 6.4 m/s to 15.2 m/s and at normal impact angle. The detachment of flake and dislodgement of whisker were identified as the major mechanisms of material removal in slurry environments. The composites showed better erosion resistance due to the protection of the matrix by the whisker at low slurry velocities. Because of reduced fracture strain, the erosion rates of the composites were generally greater than that of the unreinforced alloy at high slurry velocities. Owing to interfacial reaction which resulted in decrease in hardness and fracture strain,the T6 treatment for the composites had a deleterious influence on the erosion resistance. By considering the material removal processes in the water slurry, a simple rationalization of the inverse dependence of slurry erosion rate on Hεf was obtained. In the saline slurry, there exists a strong synergistic effect between erosion and corrosion. The volume loss of the composites was enhanced through cracking of flakes and detaching of whisker induced by stress and corrosion.