Dao Tuong Ly Kiet, Tieu Kiet Anh, Tran Bach Hoang
School of Mechanical, Materials, Mechatronic and Biomedical Engineering, University of Wollongong, Northfield Avenue, Wollongong, NSW, 2522, Australia.
Phys Chem Chem Phys. 2022 Aug 31;24(34):20282-20293. doi: 10.1039/d2cp01601j.
In this study, the tribological properties of a series of layered double hydroxides (LDHs) intercalated by various phosphate anions (hydrogen phosphate, orthophosphate, pyrophosphate, and hexametaphosphate) were investigated by ball-on-disc testing in safflower oil which has a super high content of oleic acid (OA). The Mg-Al-NO LDH precursor was first synthesized by a coprecipitation method, and then nitrate anions were substituted by different phosphate anions anion exchange. The successful intercalations were confirmed by X-ray powder diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) analysis. The tribological results indicate that the antiwear properties increased linearly with the basic strength of the phosphate anions. Stronger bases, such as orthophosphate (PO) and pyrophosphate (PO), encourage the dissociation of OA to form a protective oleate tribofilm on steel surfaces, leading to more than 40% wear reduction compared to the base oil. The tribological performance of the best antiwear candidate, PO-LDH, was studied further under different loads and concentrations. A comparison between PO-LDH and other nanomaterials was also carried out with PO-LDH exhibiting a comparable performance against hexagonal boron nitride (BN).
在本研究中，通过在油酸（OA）含量超高的红花油中进行球盘试验，研究了一系列由各种磷酸根阴离子（磷酸氢根、正磷酸根、焦磷酸根和六偏磷酸根）插层的层状双氢氧化物（LDH）的摩擦学性能。首先通过共沉淀法合成了Mg-Al-NO LDH前驱体，然后通过阴离子交换用不同的磷酸根阴离子取代硝酸根阴离子。通过X射线粉末衍射（XRD）、傅里叶变换红外（FTIR）光谱以及扫描电子显微镜/能量色散X射线光谱（SEM/EDS）分析证实了成功插层。摩擦学结果表明，抗磨性能随磷酸根阴离子的碱性强度呈线性增加。更强的碱，如正磷酸根（PO）和焦磷酸根（PO），促使油酸解离，在钢表面形成保护性油酸摩擦膜，与基础油相比，磨损减少超过40%。对最佳抗磨候选物PO-LDH在不同载荷和浓度下的摩擦学性能进行了进一步研究。还对PO-LDH与其他纳米材料进行了比较，结果表明PO-LDH与六方氮化硼（BN）具有相当的性能。
