Effect of LDH core size on the tribological properties of solvent-free nanofluids

Solvent-free nanofluids (NFs) based on a variety of lubrication core materials have attracted extensive attention in tribology, but it is still an open field to explore the relationship between size of core and tribological properties of NFs. In this paper, the multi-layer, ultrathin and ultrafine layered double hydroxides solvent-free nanofluids (ML-LDH-NFs, UT-LDH-NFs and UF-LDH-NFs) are proposed for lubricant. Compared with UT-LDH-NFs, ML-LDH-NFs exhibit better friction reduction and wear resistance performance for the interlayer sliding in multi-layer layered double hydroxides, UF-LDH-NFs with smaller lateral size is easier to slip into the sliding interface to form tribofilm, and thus provide more effective friction-reducing and anti-wear. This research provides fundamental insights into size effects of core materials for solvent-free nanofluids lubricants.