Investigation of microstructure and selected properties of Al2O3-Cu and Al2O3-Cu-Mo composites

Abstract The scope of work included the fabrication of ceramic-metal composites from the Al₂O₃-Cu and Al₂O₃-Cu-Mo and examining their microstructure and selected properties. The composites were fabricated by the slip casting method. The rheological behavior, microstructures, X-ray analysis, and mechanical properties were investigated. The rheological study demonstrated that all of the obtained slurries were non-Newtonian shear diluted fluids and stability on time. In both slurries, the flow limit is close to 0 Pa, which is very beneficial when casting the suspensions into molds. The X-ray analysis reveals Al₂O₃, Cu, and Mo phases in all specimens. No new phases were found in both types of composites after the sintering process. The results provided that the hardness for Al₂O₃-Cu-Mo composites was equal to 10.06 ± 0.49 GPa, while for Al₂O₃-Cu, it was equal to 6.81 ± 2.08 GPa. The K_1C values measured, with the use of Niihara equation, for composites with and without the addition of Mo were equal to 6.13 ± 0.62 MPa m^0.5 and 6.04 ± 0.55 MPa m^0.5, respectively. It has been established that the mean specific wear rates of Al₂O₃-Cu and Al₂O₃-Cu-Mo samples were 0.35 × 10–5 ± 0.02 mm³ N⁻¹ m⁻¹ and 0.22 × 10–5 ± 0.04 mm³ N⁻¹ m⁻¹, respectively. It was found that molybdenum addition improved wear resistance properties of the composites.