Abstract:
Graphene oxide (GO)-reinforced alumina (Al2O3) composites have garnered significant
attention for aerospace applications due to their enhanced mechanical properties. This
study investigates the synthesis, sintering behaviour, and mechanical characterization
of GO-alumina composites fabricated using powder metallurgy. GO concentrations of
0.5, 0.9, and 1.2 wt.% were incorporated into an alumina matrix and processed via
uniaxial cold pressing at 450 MPa, followed by liquid-phase sintering at 1500°C and
1550°C for dwell times of 60 and 90 minutes.
Material characterization through X-ray diffraction (XRD) confirmed the presence of
beta or gamma alumina, while Raman spectroscopy demonstrated the structural
integrity of GO within the composite. Scanning electron microscopy (SEM) revealed a
uniform dispersion of GO at lower concentrations but agglomeration at 1.2 wt.%,
adversely affecting densification and mechanical performance. The relative density of
the composites decreased with increasing GO content due to the formation of porous
regions and weak interfacial bonding. The highest relative density (91.45%) was
observed in pure alumina sintered at 1550°C for 90 minutes, while GO-reinforced
samples exhibited reduced densification efficiency. Vickers microhardness testing
indicated peak hardness at 0.5 wt.% GO, reaching 1838 HV at 1550°C for 90 minutes.
However, higher GO content (>0.9 wt.%) led to a decline in hardness due to increased
porosity and structural defects.
The research finding indicate the potential of GO-alumina composites for aerospace
applications but also underscores the limitations of conventional liquid-phase sintering
in achieving optimal densification and mechanical properties. Compared to Spark
Plasma Sintering (SPS), which provides rapid heating, improved grain refinement, and
reduced porosity, the current processing method resulted in lower densification and
increased defect formation. Future work should explore SPS to mitigate agglomeration,
enhance densification efficiency, and improve the overall performance of GO-alumina
composites.
