Electrical conductivity enhancement of nanodiamond–nickel (ND–Ni) nanocomposite based magnetic nanofluids

The stable nanodiamond–nickel (ND–Ni) nanocomposite based magnetic nanofluids were prepared by dispersing them into water (W) and ethylene glycol (EG) without adding any surfactant and their electrical conductivity has been investigated experimentally. The nanocomposite was synthesized by an in-situ method and characterized by X-ray diffraction, micro-Raman, high-resolution transmission electron microscopy, and vibrating sample magnetometer. The electrical conductivity investigations were performed in very low particle concentrations of 0.02%, 0.05% and 0.1% in the temperature range from 24 °C to 65 °C. The results indicate that an anomalous increase in electrical conductivity was observed with an increase in particle loadings in both the base fluids of water and ethylene glycol. The enhancement values in electrical conductivity for 0.1% of water based ND–Ni nanofluid are 1339.81% and 853.15% at temperatures of 24 °C and 65 °C, respectively compared to water without particles. Similarly, the enhancement values in electrical conductivity for 0.1% of EG based ND–Ni nanofluid are 199.52% and 200.23% at temperatures of 24 °C and 65 °C, respectively compared to EG without particles. Conventional models, such as the Maxwell model and the Bruggeman correlation were considered for comparison and we observed disagreement.