INFLUENCE OF STRUCTURAL PARAMETERS ON THE SLURRY EROSION RESISTANCE OF SQUEEZE-CAST METAL MATRIX COMPOSITES

Metal matrix composite specimens were made by squeeze casting, where 5083 aluminum alloy infiltrates a fiber preform. The ceramic fibers consisted of Al2O3 (47%) and SiO2 (53%), The use of different preforms resulted in specimens with fiber volume fractions of 10%, 15% and 20%. Erosion tests were performed with a slurry jet having a velocity of 15 m s-1 and a sand concentration of 10 wt.%. Different size distributions of silica sand particles were chosen as abrasive. The results are presented in the form of erosion profiles of different specimens. Although the erosion resistance increases with fiber volume fraction, the erosion profile variations are negligible. Due to the trajectory deviation of abrasive particles near the surface, the erosion conditions (particle velocity, local impact angle) are greatly modified for different abrasive particle sizes. Large abrasive causes fiber fracture which results in poor protection of the matrix by the fibers. This results in gradual erosion of the surface with no relief. For small abrasive particles, the erosion of the matrix is more important than that of the fibers, resulting in a rough eroded surface, especially in the region where the local impact angle is small. These results are interpreted in terms of the structural parameters of the composites.