Preparation Of Nanocrystals Alloy By The Solution Dispersion And Investigation Of Their Tribological Properties

Nano alloys with low-melting-point were synthesized in poly-glycol and microemulsions system in the presence of long-chain amphiphilic copolymer as a surface modifier. The formation mechanism of the nano alloys was discussed. The tribological properties of the alloy nanocrystals as additives in lubricating oil were evaluated using a friction and wear tester. Results show that the low-melting-point alloy nanocrystals have excellent antiwear performance and can improve the load-carrying capacity of base oil.The thesis mainly contains three parts:(1) Polystyrene with halogen (PSt-X) was synthesized by atom transfer radical polymerization (ATRP) using ethyl 2-bromopropionate as the initiator and CuCl/ bipyridyl (bpy) as the catalyst. Then PS-b-polymethyl methacrylate copolymer was obtained via block polymerization of methyl methacrylate in the presence of PSt-X as the macroinitiator. Finally, the copolymer was hydrolyzed in 1,4-dioxane to get amphiphilic copolymer in the presence of HC1. And the amphiphilic copolymer was characterized by means of nuclear magnetic resonance (NMR) spectrometry, infrared (IR) spectrometry, and gel permeation chromatography (GPC).(2) Pine needle-like quaternary nanocrystals alloy was synthesized in liquid paraffm/water/P123 micro-emulsion system. The structure, composition and morphology of the samples were studied by means of transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetry/differential thermal analysis (TG/DTA). The formation mechanism of the needle-like quaternary nanocrystals alloy was discussed. Results show that the nanocrystals had pine needle-like morphology and were composed of a large number of cubby nanoparticles.(3) The core-shell structures of In-Sn binary alloys were synthesized in poly-glycolsystem using P123 as the surfactant. The products were characterized by means of TEM, XRD, and TG/DTA. The possible growth mechanisms of the core-shell nanostructures were discussed.(4) The tribological properties of alloy nanocrystals as additives in lubricating oil were evaluated using a four-ball friction and wear tester and ring-on-block friction and wear tester. The worn surfaces were analyzed by means of SEM and energy dispersice spectrometry (EDS), and the wear mechanisms were analyzed. Results show that the alloy nanoparticles as lubricating oil additives can significantly improve the anti-wear and friction-reducing performance of the base oil.