Abstract

Eu-doped WO₃ (WO₃:Eu³⁺) nanoparticles were prepared by Pechini method under different pH values (pH 1, 3, 5, and 7). The prepared nano-powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). The results showed that the average external diameter of the prepared nano-WO₃:Eu³⁺ powders is the smallest and reaches 50 nm at pH 5. Structural transformation matrix contained different crystals of anorthic and orthorhombic structures. Eu³⁺ ions are located at the center of the non-inversion symmetry of WO₃:Eu³⁺. The tribological properties of the WO₃:Eu³⁺ as extreme pressure and wear resistance agents in water-based lubricant were investigated by a four-ball machine. The results showed that WO₃:Eu³⁺ displays excellent load-carrying capacity, wear resistance, and friction-reducing properties in water-based lubricant, particularly in the best concentration of WO₃:Eu³⁺ was 0.6 wt%. WSD was reduced from 0.62 to 0.35 mm and COF was decreased from 0.083 to 0.055. This was due to the formation of tribofilms with a few tens of nanometers thick, which prevented no actual metal-to-metal contact.

Graphical Abstract

中文翻译：

---

pH值对Eu掺杂WO 3纳米粒子在水基流体中的摩擦学行为的影响

摘要

通过Pechini方法在不同的pH值（pH 1、3、5和7）下制备Eu掺杂的WO ₃（WO ₃：Eu ³⁺）纳米颗粒。通过X射线衍射（XRD），透射电子显微镜（TEM）和高分辨率透射电子显微镜（HRTEM）对制备的纳米粉进行表征。结果表明，所制备的纳米WO ₃：Eu ³⁺粉末的平均外径最小，在pH 5时达到50 nm。结构转变基质中含有不同的正斜和正交晶体。Eu ³⁺离子位于WO ₃：Eu ^{3+的同相对称中心}。用四球机研究了WO ₃：Eu ³⁺作为水基润滑剂中的极压和耐磨剂的摩擦学性能。结果表明，WO ₃：Eu ³⁺在水基润滑剂中显示出优异的承载能力，耐磨性和降低摩擦性能，特别是在WO ₃：Eu ³⁺的最佳浓度为0.6 wt％时。WSD从0.62毫米减少到0.35毫米，COF从0.083减少到0.055。这是由于形成了几十纳米厚的摩擦膜，这阻止了实际的金属间接触。

图形概要