Effect of surface modification on the stability and thermophysical properties of copper oxide nanolubricants

It is of significant economic value to improve the stability and thermophysical properties of the lubricating oil utilized in turbine thrust bearings. Adding copper oxide (CuO) nanoparticles to the lubricating oil is an effective modification method. In this study, an organophilic silane coupling agent, γ-methacryloxypropyltrimethoxysilane (abbreviated as γ-MPS), was employed for the surface modification of CuO nanoparticles to enhance the suspension stability of CuO nanofluids. The results indicate that the modification was successful, with a grafting rate of 21.552 %. The γ-MPS modified CuO nanofluid exhibited a lower agglomeration effect, and the size of the agglomerated CuO nanofluid decreased from 479.8 nm to 356.7 nm compared to the unmodified CuO nanofluid. The γ-MPS modified CuO nanofluid remained stable without sedimentation for 14 days. At 90 °C, its viscosity increased from 19.3 mPa·s to 20.56 mPa·s, and its thermal conductivity rose from 0.1797 W/m·K to 0.1903 W/m·K, compared to the unmodified CuO nanofluid.