Preparation Of Bi Nanoparticles As Ester-based Lubricant Additivesand Investigation Of Their Tribological Behavior

Metallic Bismuth is a green element and its nanostructurized forms exhibit excellent tribological properties. Synthetic ester oils based on renewable sources are green to the environment and have a great importance among all of the lubricating base oils. However, few literatures are currently available about applyling bismuth nanoparticels as lubricant additives. In addition, much fewer reports ever have considered to combine nano bismuth with ester oils in order to form a green lubricant. In this paper, Bi nanoparticles was synthesized by both chemical reduction method and thermal decompostion method. The tribological properties of as-synthesized Bi nanoparticles as an additive in three kinds of ester oils were investigated with a four-ball tester. The main contents and results of this paper are listed as follows:(1) Preparation of Bi Banoparticles via a Chemical Redution Method and Investigation of its Tribological Properties in Three Kinds of Ester oilsBismtuh nanoparticles modified by O-O’-dioctyl dithiophosphinic adic (C8DDP) were synthesized via a simple chemical reduction method Results show that the Bi nanoparticles have an average paricle diameter of3.7nm and thus can be dispersed well in ester based oils. Meanwhile, the surface-modified Bi nanoparticles as lubricating additives possess excellent friction reduction and anti-wear properties.(2) Preparation of Bi Nanoparticles via a Thermal Decompostion Method Investigation of its Tribological Properties in Three Kinds of Ester oilsBismtuh nanoparticles with an average paricle diameter of17nm were in-situ synthesized via a simple one-step thermal decomposition method with Bi(SH25C12)3as the precursor, oleylamine as the solvent as well as oleic acid as the surface-capping agents. The tribological properties of as-synthesized Bi nanoparticles as an additive in three kinds of ester oils were investigated with a four-ball tester. As-prepared Bi nanoparticles can effectively improve the friction-reducing and anti-wear ability as well as load-carrying capacity of ester oils. Due to its low melting point, Bi nanoparticles can form a liquid film on the worin surface resulting its great tribological properties during friction process.