الفهرس 
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Abstract
Lubrication is the process or technique employed to reduce wear of one or both surfaces in close proximity, moving relative to each other, by interposing a substance called lubricant between the surface to carry or to help carry the load (pressure generated) between the opposing surfaces. Typically lubricants contain 90٪ base oil (most often petroleum fractions, called mineral oils) and less than 10٪ additives, The functions of additives are improve oil viscosity index , increase oil oxidation stability, prevent lacquers , prevent wear , reduce fraction , prevent scuffing, depress oil pour point , prevent rust formation, prevent foaming. Nanoparticles and materials in nanoscale have a great attention in the last two decades due to their unique and special properties which cannot provide by bulk materials, they have several applications in many fields and recently, nanoparticles have been used in lubricant as additives to improve its physical and tribological properties rather than pure lubricant, For example; Ehsan-o-llah Ettefaghi studied engine oil properties containing copper oxide nanoparticles as a nanoadditive, Xianbing Ji used cubic CaCO3 nanoparticles as a nanoaditives, Yue Gu, applied surface modified titanium dioxide (TiO2) nanoparticles, Z.S. Hu., prepared amorphous lanthanum borate Nanoparticle as a nanoadditives, and many other studies. In The present study we prepared 40 nm ZnO nanoparticles in organic media using chemical reduction method, and 40 nm amorphous SiO2 nanoparticles from rice husks using Hydrochloric acid, Sulfuric acid and Sodium hydroxide, and also prepared 3 nm Al2O3 nanoparticles by sol gel method using Aluminium nitrate, Ammonium xvi carbonate, Nitric acid and Sodium hydroxide and then applied surface modified using oleic acid. Then prepared different concentration (0.05wt%, 0.1wt%, 0.2wt%) of nanolubricants of each nanoparticles and used these in measuring of viscosity (according to ASTM D445), flash point (according to ASTM D92), pour point (according to ASTM D97), antiwear ability (according to ASTM D4172), thermal stability (according to ASTM D2272) and photostability by Light emitting diod (LED) at three different wave length (488nm, 532nm, 612nm). The characteristics of nanoparticles carry out by the transmission electron microscopy (TEM), X- ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The results obtained illustrated that the flash point improved by ( 4.3%, 3%, 3%) for surface modified Al2O3 nanolubricant, ZnO nanolubricant, and SiO2 nanolubricant, respectively with respect to pure lubricant, where ZnO, SiO2, and surface modified Al2O3 nanoparticles have high melting point and heat content, and from previous study they found that these nanoparticles increases the thermal conductivity and specific heat capacity of the fluid so it increases the oil resistance to ignition and increases the flash point of nanolubricant with respect to lubricant oil without nanoparticles. Also It is observed that there is an improvement for pour point measurement rather than pure lubricant at concentration 0.05 wt٪ of modified alumina nanoparticles by 150٪, and for all concentrations of SiO2 nanoparticles by 50٪, where add surface modified alumina nanoparticles, and silicon oxide nanoparticles (0.05wt ٪) to the lubricant, it adsorbed on the surface of wax crystals in oil lubricant and prevents its growth. By measuring of thermal stability of all nanoaditives concentration the result show that the addition of the lowest concentration of surface modified Al2O3 nanoparticles (0.05wt٪) increases the xvii thermal stability of lubricant oil by 33٪ with respect to pure lubricant and this is due to destruction of hydrocarbon and hydroperoxide radicals by formation of stable complex with metal ions. The result of measuring of wear prevention show that lubricant contain lowest concentration (0.05 wt٪) of SiO2 nanoparticles decrease scare diameter by 19% rather than pure lubricant, and 0.05wt٪ of surface modified Al2O3 nanoparticles has scar diameter less than lubricant alone by 9.4 ٪ while 0.05 wt٪% of ZnO nanoparticles reduce scare diameter by 3.2% with respect to pure lubricant, which result may due to deposition of nanoparticles on the rubbing surfaces forming a boundary thick film during the friction process which reduces the wear and improves the anti-wear properties of nanolubricants. For pure lubricant, a strong absorbance at wavelengths below 400 nm, which mean presence of olefinic and aromatic components of base oil, show no change in absorption bands (no photo degradation of pure lubricant) after irradiated at three different wave length (488nm, 532nm, 612nm) for 12 hours. Photostability of each nanolubricants measured by the same method show bands at 250-300nm, bands at 300-310nm, bands at 390nm corresponding to ZnO, SiO2, and Al2O3 nanoparticles respectively, and strong bands below 400nm for base oil without change, So no effect of nanoparticles about the stability of pure lubricant. So it seems that the 0.05wt% of surface modified Al2O3 nanolubricant and 0.05wt٪ of SiO2 nanolubricant are the best samples because in these samples pour point, flash point, scare diameter are improved and viscosity has not changed much.