Effect of ZrO2 nanoparticles on thermophysical and rheological properties of three synthetic oils

This article presents an experimental study on some thermophysical properties (density, viscosity and adiabatic bulk modulus) of six nanolubricants based on synthetic oils and ZrO2 nanoparticles. Two-step method with ultrasonic disruptor was used to prepare the nanodispersions. The morphology, crystalline degree and elemental composition of nanoparticles were analyzed by electron microscopy. Visual observation, temporal variation of refractive index and dynamic light scattering were used to analyze the stability of the nanolubricants and the average size of the aggregates. The presence of new interactions between nanoparticles and base oils was studied through Fourier transform infrared spectrometer. Vibrating tube densimeters, rotational viscometer and rheometer equipped with cone-plate geometry were used within the temperature range from (278.15 to 373.15) K. The ability of some theoretical simple models to predict densities and viscosities of these nanolubricants as a function of temperature and nanoparticle concentration was also checked.