Preparation and Characterization of γ-Al2O3/Al Composite

A cermet (ceramic-metal) composite have been prepared from alumina (γ-Al2O3) reinforced with aluminum (Al) for the concentrations of (0, 10, 20, 30, 40, 50) wt. %Al. The cermet was formed by single axial pressing, sintered in vacuum atmosphere. Compaction behaviors were studied in solid state sintering at sintering temperatures (400, 450, 550) °C, sintering times (2, 4, 6) hrs., and forming pressures (5, 10, 15) MPa, also in liquid phase sintering at (800 °C). The cermet was characterized by x-ray diffraction (XRD) and by scanning electron microscope (SEM), also physical and mechanical properties have been studied. SEM results showed the Al flowing inside the ceramic body due to uniform distribution of Al particles and due to sintering temperature (800 °C) have been used. XRD results showed that there is no new phase formed between Al and Al2O3 after sintering due to there is no chemical reaction but physical reaction between them. The existence of Al enhanced the physical properties as the sintering (time temperature) and pressure increase. Hardness values increased to 30 wt. % Al then decreased due to Al ductility. The oxide layer on the friction surfaces played important role for increasing wear rate.