On the Physical–Chemical and Magnetic–Thermal Properties of Magnetite Magnetic Fluids with the Addition of Graphene

Abstract

In this work, the synthesis of a magnetite/graphene composite and a magnetic fluid based on it is carried out. The physical–chemical and magnetic–thermal properties of the obtained samples are studied. It is established that in the magnetite/graphene composite magnetite nanoparticles are adsorbed on the graphene surface in the form of aggregates. It is found that the specific surface area and pore volume of the magnetite/graphene composite are higher than the values for magnetite. Analysis of the rheological curves of the magnetic fluid characterizes its structure as homogeneous and indicates a uniform distribution of the dispersed phase in the dispersion medium. It is established that the magnetic fluid with the composite is thermally stable up to 210°С. The values of the specific heat capacity of the synthesized sample are slightly higher than the heat capacity of the liquid without graphene additives. It is noted that the addition of an insignificant part of graphene to the magnetic phase of the magnetic fluid leads to a twofold increase in the value of the magnetocaloric effect (MCE) and changes the shape of the temperature dependence of the MCE in the studied temperature range.