Liquid-phase shear exfoliation combined with hydrothermal processing for the preparation of graphene nanosheet/AlOOH nanofiber composite powder to enhance high-temperature performance of MgO-carbon castable

Abstract

Flake graphite (FG) poses challenges for incorporation into castables due to its hydrophobic nature. In this paper, a strategy combining liquid-phase shear exfoliation (LPSE) with hydrothermal processing was proposed to produce hydrophilic graphene nanosheet/AlOOH nanofiber (GN/ANF) composite powders to address this issue. Under optimal shear exfoliation conditions, the yield of graphene nanosheets (GNs) reached up to 57%. Following a straightforward hydrothermal treatment, the water contact angle of as-prepared GN/ANF composite powders decreased to 53.1°, compared to 103.6° of the original FG. Benefiting from the hydrophilic properties of the composite powders and the homogeneous dispersion of GNs in MgO castables, the sample containing 0.5 wt% GNs exhibited better high-temperature performance than its counterparts. Relative to the control specimen, the slag corrosion index of the sample containing 0.5 wt% GNs decreased from 0.60 to 0.13, while the thermal shock resistance increased by approximately 2.8 times.