Mechanical and Structural Properties of Graphene Oxide and Reduced Graphene Oxide Doped YBCO

YBCO (Y 1 Ba 2 Cu 3 O 7-δ ) was doped with graphene oxide (GO) and reduced graphene oxide (rGO) in the following percentage weight concentrations: 0.1, 0.5 and 1% wt.. Lattice parameters, crystallite size, orthorhombicity and lattice strain were calculated using XRD analysis. The porosity of samples decreased by a maximum of 29% and 17% for GO and rGO doped samples respectively. Microhardness measurements were conducted using the Vickers hardness method at loads in the range of 0.245 - 2.940 N. These micro hardness measurements were used to calculate the Vickers hardness ( H V ), elastic modulus ( E ), yield strength ( Y ), fracture toughness ( K IC ) and brittleness index ( B ) of the material. H V was greater in GO doped samples than in rGO doped samples. E increased by 63.94% for rGO and 85.52% for GO doped samples. Y increased by 63.80% for rGO and 85.40% for GO doped samples. B decreased by 48.11% for rGO and 43.78% for GO doped samples. There was an increase in K IC for both GO and rGO samples. The indentation size effect (ISE) was observed during micro-hardness measurements. This ISE behaviour was analyzed using Meyers Law, PSR model, elastic/plastic deformation model and Hays Kendall model. The results showed that the Hay Kendall approach best described the ISE behaviour of the samples.