Strengthening mechanism of graphene oxide nanosheets for Al2O3–C refractories

Significant improvement of refractoriness of Al2O3–C castables containing calcium aluminate nano-coatings on graphite

“…According to the XRD report, similar compounds had also been formed in the C+ refractory castable. Literature also shows that graphene oxide nanosheets can promote the formation of silicon carbide whiskers in the Al 2 O 3 ͲC refractory at high temperature [13]. It is due to the higher reactivity of graphene oxide nanosheets (GONs) than graphite flakes that yielded silicon oxycarbide fibers with high aspect ratio to strengthen the refractory.…”

“…The sol gel coating therefore inhibits contact between atmospheric oxygen and graphite to lower down the enthalpy change in case of uncoated graphite. It also reveals that the activation energy needed for oxidation is lower in coated graphite; it could be due to evolution of reactive nanosheets of exfoliated graphene oxides after sol gel treatment and calcination [13,24]. It has been reported that calcium doped gamma -alumina via sol -gel route progressively crystallizes to calcium aluminate at around 930 0 C [22,23].…”

“…As such the Ca 2+ and Al 3+ ions from calcium doped ɶͲAl 2 O 3 in functionalized graphite layers help in controlled clumping to withstand high pressure on C+ matrix with increasing temperature. Last but not the least, the reactive nanosheets of graphite also helped to develop the silicon carbide phases in the castable matrix even at elevated temperature [13]. The XRD plot of fired C+ matrix (Fig.…”

Extended studies on surface‐treated graphite vis‐à‐vis its application in high alumina refractory castable

“…The small peak in all three graphites nearby 300°C can be due to chemisorptions and other reasons stated elsewhere . Nevertheless, the exothermic peak tip of Gc at 931°C signifies that less activation energy is required for its application; it is certainly due to existence of expanded and reactive graphite sheets with higher surface area . It also consists of nanosized γ‐Al 2 O 3 phases crosslinked between graphite platelets.…”

“…Nanoscale materials are employed in several sectors of advanced ceramics applications. Refractory technology has also been inducted by these materials leading to some sophistication in their existing properties by tuning the microstructure by newer additives or whiskers . Novelties have thus been adopted with regard to carbon‐based nanomaterials, such as carbon nanotubes, graphene oxide nanosheets etc.…”