The processing conditions for preparing well dispersed silica–graphene nanoplatelets and
silica–graphene oxide nanoplatelets (GONP) composites were optimized using powder and
colloidal processing routes. Fully dense silica–GONP composites with up to 2.5 vol% loading
were consolidated using spark plasma sintering. The GONP aligned perpendicularly to the
applied pressure during sintering. The fracture toughness of the composites increased linearly
with increasing concentration of GONP and reached a value of
∼
0
.
9 MPa m
1
/
2
for 2.5 vol%
loading. Various toughening mechanisms including GONP necking, GONP pull-out, crack
bridging, crack deflection and crack branching were observed. GONP decreased the hardness
and brittleness index (BI) of the composites by
∼
30 and
∼
50% respectively. The decrease in
BI makes silica–GONP composites machinable compared to pure silica. When compared to
silica–Carbon nanotube composites, silica–GONP composites show better process-ability and
enhanced mechanical properties.