Superlubricity of Polyalkylene Glycol Aqueous Solutions Enabled by Ultrathin Layered Double Hydroxide Nanosheets.
Hongdong WangYuhong LiuWenrui LiuYanmin LiuKunpeng WangJinjin LiTian-Bao MaOsman Levent EryilmazYijun ShiAli ErdemirJianbin LuoPublished in: ACS applied materials & interfaces (2019)
It was previously proved that the existence of a large amount of hydrogen ions in water-based lubricants can easily lead to a superlubric state; however, it was also shown that these hydrogen ions could cause severe corrosion. As part of a large family of attractive clays, layered double hydroxides (LDHs) possess excellent tribological properties in water-based lubrication systems. In the present work, two different kinds of LDHs are dispersed in polyalkylene glycol (PAG) aqueous solutions, in two distinct forms: ultrathin nanosheets (ULDH-NS) of ca. 60 nm wide and ca. 1 nm thick (single or double layer) and nanoparticles (LDH-NP) of ca. 19.73 nm wide and ca. 8.68 nm thick. We find that the addition of ULDH-NS greatly shortens (as much as 85%) the running-in period prior to reaching the superlubricity regime and increases the ultimate load-bearing capacity by about four times. As compared to the fluid film thickness of the lubricating PAG solution, their ultrathin longitudinal dimension will not impair or influence the fluid film coverage in the contact zone. The analysis of sliding solid surfaces and the atomic force microscope microscale friction test demonstrate that the adsorption of ULDH-NS enables the sliding solid surfaces to be polished and protected because of their relatively weak interlayer interaction and increased adhesion effect. Owing to their superior tribological properties as lubricant additives, ultrathin LDH nanosheets hold great potential for enabling liquid superlubricity in industrial applications in the future.
Keyphrases
- reduced graphene oxide
- metal organic framework
- quantum dots
- photodynamic therapy
- high efficiency
- dengue virus
- aqueous solution
- gold nanoparticles
- biofilm formation
- protein kinase
- visible light
- ionic liquid
- light emitting
- escherichia coli
- healthcare
- zika virus
- room temperature
- optical coherence tomography
- highly efficient
- high intensity
- transition metal
- pseudomonas aeruginosa
- staphylococcus aureus
- cell migration
- cystic fibrosis