Photonic crystals in biology - NanoTR-VI

PPP HR3RBOR3Poster Session, Thursday, June 17Theme F686 - N1123Performance of Zinc Borate Nanoparticles as an Anti-Wear Additive in Mineral Oil1211USevdiye Atakul SavrkUP P*, Mehmet GönenP P, Devrim BalköseP P, Semra ÜlküP1Pzmir Institute of Technology, Department of Chemical Engineering, Gülbahçe Köyü, Urla, zmir, Turkey2PPresent address: Süleyman Demirel University, Department of Chemical Engineering, Isparta, TurkeyAbstract- Inorganic borates as a lubricating oil additive received extensive attention in recent years due to the remarkable tribologicalproperties such as wear resistance, friction-reducing ability and oxidation inhibition. This study reports the synthesis of nano-sized zinc borate,its characterization as well as its performance in mineral oil as a lubricating additive. Zinc borate nanoparticles with different morphologieswere prepared by two different raw materials groups. Spherical crystals were successfully synthesized by precipitation reaction in aqueoussolutions of NaR2RBR4ROR7R·10HR2RO and ZnNR2ROR6R·6HR2RO, whereas supercritical ethanol drying method is applied to prepare broccoli type speciesafter the precipitation step in aqueous solutions of HR3RBOR3R and ZnO. The lubricants were prepared by dispersing the zinc borate particles withsorbitan monostearate (Span 60) which was used as a surface modifier. The tribological properties of the mineral oil were determined by fourballwear test machine and the results indicated that wear scar diameter is reduced by 54.78% for the lubricant including zinc borate dried bysupercritical ethanol drying compared to that of the mineral oil.The increasing interest of petrochemical industries onimproving the performance of their products (lubricants,greases, gasoline, among others) has been simultaneouslygenerating great incentives to develop additives that are ableto supply the commercial demand of the competitive industrialmarkets. For tribology applications, particles as additives inbase oil have been investigated widespreadly. These studiesrefer to synthesis and preparation of especially nanoscaleparticles, and their tribological properties and mechanisms[1,2]. The lubrication performance of a lubricant relies partlyupon the thickness of the tribofilm under the severe conditionscontrolled by several parameters such as load, temperature,sliding speed and the mechanical properties of the film. Avariety of mechanisms have been proposed to explain thelubrication enhancement of the nanoparticles suspended inlubricating oil. Ball bearing effect and protective filmmechanisms have direct effect of the nanoparticles onlubrication enhancement, whereas mending and polishingeffects have secondary effect on surface improvement [3].This study aims to investigate the tribological properties ofmineral oil including zinc borate nanoparticles and to exposethe effect of morphology of the particles on anti-wearproperty.In this project, first group of zinc borate species wereobtained by the homogenous precipitation method describedby Ting et al. using ZnNR2ROR6R·6HR2RO, NaR2RBR4ROR7R·10HR2RO andammonia [4]. Second group of zinc borate nanoparticles were3prepared by 4.7mol/dmPRwith the stoichiometricamount of ZnO. Supercritical ethanol drying of submicronzinc borate was performed at 250 °C, 6.5 MPa for obtainingnano zinc borate particles. All zinc borate samples werecharacterized by SEM, TGA, DSC, FTIR, and XRD. Thelubricants were prepared by adding sorbitan monostearate(Sigma Aldrich) and zinc borate particles into the mineral oilat 70 °C. They were mixed by both a homogenizer (OMNIGLH) and a magnetic stirrer (Yellowline MSH Basic) for 2minutes and 2 hours, respectively. Tribologicalcharacterization of the lubricants was carried out by a fourballwear test machine (made by Falex Corp.) The test ballswere chrome alloy steel, No. E-52100 with a diameter of 12.7mm. The wear and friction test was performed at 392 N andthe test duration was 1h. After the test, the morphology ofworn surfaces of the balls run in the lubricant was obtained bySEM. Moreover, elemental composition of the ball wornsurfaces was determined by EDX analysis.SEM images of zinc borate nanoparticles produced bydifferent raw materials groups are shown in Figure 1. Thezinc borate obtained by ZnNR2ROR6R·6HR2RO andNaR2RBR4ROR7R·10HR2RO includes spherical crystals (Figure 1a). Onthe other hand, zinc borate crystals dried by supercriticalethanol have broccoli type morphologies. Table 1 reports thetribological properties of the lubricants. It was revealed thatsorbitan monostearate had a dramatic role in the reduction ofwear scar diameter from 1.402 to 0.656 mm. When thenanoparticles dried by supercritical ethanol were used aslubricating oil additives, wear scar diameter is reduced to0.634 mm.(a)(b)Figure 1. SEM images of super critical ethanol dried nanoparticlesobtained from zinc borates a) ZnNR2ROR6R·6HR2RO and NaR2RBR4ROR7R·10HR2ROand b)HR3RBOR3R and ZnOTable 1. Tribological properties of lubricantsWear Scar FrictionSample AdditiveDiameter (mm) CoefficientL1 - 1.402 1.645L2 Span 60 0.656 1.635L3ZB dried bySCE +Span 600.634 1.601SEM analysis shows that the worn surface of the balllubricated with L3 lubricant including zinc borate andsurfactant exhibits much smoother surfaces without severescuffing. Additionally, EDX analysis reveals that boron andzinc elements are also adsorbed by the worn surface of theball.TÜBTAK (project number: 105M358), OPET PetrolcülükA. and Izmir Institute of Technology Centre for MaterialResearch are greatly appreciated.HT*Corresponding author: sevdiyeatakul@iyte.edu.trT[1] Zhang M., Wang X., Fu X., Xia Y., 2009. Performance andanti-wear mechanism of CaCOR3 Rnanoparticles as a green additive inpoly-alpha-olefin, Tribology International, 42:1029-1039.[2] Choundary R.B., Pande P.P., 2006. Lubrication potential ofboron compounds: an overview. Lubrication Science, 14: 211-222.[3] Lee K., Hwang Y., Cheong S., Choi Y., Kwon L., Lee J., KimS.H., 2009. Understanding the role of nanoparticles in Nano-oillubrication, Tribology Letters, 35: 127-131.[4] Ting C., Cheng D.J., Shuo W.L., Gang F., 2009. Preparationand characterization of nano-zinc borate by a new method, Journalof Material Processing Technology, 209:4076-4079.6th Nanoscience and Nanotechnology Conference, zmir, 2010 733