Abstract Commercially prepared spherical zirconia (ZrO2) nanoparticles with an average particle diameter of 5 nm and functionalized with a hydrocarbon ligand were dispersed in a polyalphaolefin (PAO) base oil, producing a 10-nm stabilized zirconia nanofluid. The resulting nanofluid’s properties were characterized, including thermal conductivity and viscosity. A preliminary study of the nanofluid’s ability to generate protective tribofilms was conducted. Long-term stability was verified using dynamic light scattering (DLS) and average particle size was quantified as a function of time. A 10 wt% ZrO2 nanofluid maintained a 10-nm average particle size over 25 months, with no signs of agglomeration or sedimentation, and redispersion was not necessary before analysis. The tribological performance of several concentrations of ZrO2 nanofluids wasdisc characterized with a ball-on-disc tribometer. Tribofilm growth over time was collected via optical interference imaging. Friction data collected over time are also reported. Nanoparticle concentration was varied to understand its effect on tribofilm growth. The ZrO2 tribofilm morphology and chemistry were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM).

中文翻译：

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氧化锆纳米流体的稳定性、热导率、粘度和摩擦学表征作为纳米粒子浓度的函数

摘要 将商业制备的平均粒径为 5 nm 并用烃配体官能化的球形氧化锆 (ZrO2) 纳米粒子分散在聚 α 烯烃 (PAO) 基础油中，制备出 10 nm 稳定的氧化锆纳米流体。表征了所得纳米流体的特性，包括热导率和粘度。对纳米流体产生保护性摩擦膜的能力进行了初步研究。使用动态光散射 (DLS) 验证了长期稳定性，并将平均粒径量化为时间的函数。10 重量％的 ZrO2 纳米流体在 25 个月内保持 10 纳米的平均粒径，没有团聚或沉降的迹象，并且在分析前不需要再分散。几种浓度的 ZrO2 纳米流体的摩擦学性能用圆盘摩擦计表征。通过光学干涉成像收集随时间的摩擦膜生长。还报告了随时间收集的摩擦数据。改变纳米颗粒浓度以了解其对摩擦膜生长的影响。使用扫描电子显微镜 (SEM)、能量色散 X 射线光谱 (EDS) 和透射电子显微镜 (TEM) 表征 ZrO2 摩擦膜的形态和化学特征。