On the size effect of molybdenum disulfide particles on tribological performance

Industrial Lubrication and Tribology (Impact Factor: 0.44). 11/2005; 57(6):255-259. DOI: 10.1108/00368790510622353


Purpose – To provide a suitable useful mixing ration of nano-sized molybdenum disulfide and commercial common molybdenum sulfide (MoS2) particles (approximately 1.5?µm in diameter) in liquid paraffin, which can lead to a better tribological performance. Design/methodology/approach – The MoS2 nanoparticles and commercial common MoS2 particles (approximately 1.5?µm in diameter) were dispersed in liquid paraffin with different concentrations and ratios by means of ultrasonic in order to study their lubrication capacity, friction reduction and wear resistance. The tribological experiments were carried out by MQ-800 four-ball tribometer, in which extreme pressure, wear scan diameter and friction coefficient were measured. It was analyzed that the chemical status of elements on the rubbed surface by X-ray photoelectron spectroscopy (XPS), and it was observed that the surface topography of wear scan by scanning electron microscope (SEM). Findings – The results showed that the loading capacity of liquid paraffin with different kinds of MoS2 particles were increased with their contents. The liquid paraffin containing the mixture of MoS2 nanoparticles and common MoS2 particles has a better wear resistance, friction-reducing performance and extreme pressure property than the liquid paraffin containing pure common MoS2 or pure nano-MoS2 particles. The optimal mixing ratio of nano-MoS2 and common MoS2 is 20?wt percent, the loading capacity reaches the highest value. By XPS and SEM it was suggested that the difference in the tribological performance between MoS2 nanoparticles and MoS2 common particles was attributed to the surface and interfacial size-effect of nanoparticles and the formation of molybdenum trioxide thin film on the rubbed surface. Research limitations/implications – It is not studied that the effects of mixing of common MoS2 and nano-MoS2 in the actual lubricating oil with various additives. Practical implications – It provided a basic research results and data for the application of nano-MoS2 particles. Originality/value – The mixing of nanoparticles and non-nano-sized particles will lead to new tribological results, which is different from results obtained from other nanoparticles before.

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Available from: Xianguo Hu, Feb 23, 2015
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    • "Molybdenum disulfide (MoS 2 ) is a widely used solid lubricant and liquid lubricant additive. The incorporation of MoS 2 as an additive has been shown to improve the tribological performance of liquid lubricants by facilitating the development of a durable tribofilm during boundary lubrication conditions [1] [2] [3] [4] [5] [6]. These observations have motivated further fundamental and applied research aimed at developing MoS 2 based lubricants with improved tribological performance [7]. "
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    ABSTRACT: In the present work, nanoindentation on the basal surface of a crystalline molybdenum disulfide (MoS2) thin film is investigated by molecular statics (MS) calculations. A previously parameterized interatomic potential combining the reactive empirical bond-order and Lennard-Jones potentials is implemented into the LAMMPS molecular simulation package and refined for improved prediction of the mechanical properties of MoS2 at athermal conditions. Nanoindentation simulations are performed using three indenter sizes with specific focus on the incipient plastic deformation event within the MoS2single crystal. MS calculations show that a local phase transformation occurs beneath the indenter at plastic yield without the presence of broken Mo–S bonds. The structural characteristics of the phase transformation are captured using a slip vector analysis. The nanoindentation simulations provide insight into the mechanical response of MoS2 during contact deformation characteristic of both synthesis and application for better design of MoS2 nanoparticle lubricants.
    Modelling and Simulation in Materials Science and Engineering 03/2013; 21(4):045003. DOI:10.1088/0965-0393/21/4/045003 · 2.17 Impact Factor
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    • "The tribological properties of MoS 2 are closely related to its morphology and size (Rapoport et al., 1999; Hu, 2005). Nanosized MoS 2 is generally believed to have better lubrication properties than bulk MoS 2 , and even an ultra-low friction has been observed using the lubrication of fullerene-like MoS 2 nanoparticles (Chhowalla and Amaratunga, 2000; Hu et al., 2005; Cizaire et al., 2002). As a result, morphology-controlled synthesis of nanosized MoS 2 has been attracting much attention. "
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    ABSTRACT: The decomposition of MoS<sub align="right"> 3 </sub> prepared from different sulphur sources is a very convenient method to synthesize nano-MoS<sub align="right"> 3 </sub>. It was found the sulphur sources had an obvious influence on the MoS<sub align="right"> 3 </sub> morphology and size. MoS<sub align="right"> 3 </sub> from CH<sub align="right"> 3 </sub>CSNH<sub align="right"> 2 </sub> contained hollow nano-balls or solid nanoparticles, while that from Na<sub align="right"> 2 </sub>S comprised microparticles. Heating the obtained MoS<sub align="right"> 3 </sub> hollow nano-balls and solid nanoparticles under H<sub align="right"> 2 </sub>, respectively, led to ∼150 nm MoS<sub align="right"> 2 </sub> nano-balls and ∼40 nm MoS<sub align="right"> 2 </sub> nanoparticles. However, Calcining the micro-MoS<sub align="right"> 3 </sub> from Na<sub align="right"> 2 </sub>S under H<sub align="right"> 2 </sub> produced ∼30 nm MoS<sub align="right"> 2 </sub> nanoslices. The all obtained MoS<sub align="right"> 2 </sub> samples represented a typical layered structure.
    International Journal of Materials and Product Technology 10/2010; 39(3/4):378 - 387. DOI:10.1504/IJMPT.2010.035844 · 0.26 Impact Factor
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    ABSTRACT: The tribological properties of high-density polyethylene (HDPE) modified by MoS2 with different morphologies (nano-spheres, nano-platelets, and micro-platelets) were investigated using an end-face tribometer under dry friction and rapeseed oil lubrication. Under dry friction, MoS2 nano-platelets and nano-spheres exhibited their best properties at 1.0 and 1.5 % (wt%) MoS2 content, respectively. Under oil lubrication, the nano-spheres were better additives in HDPE than the other two. The melting of HDPE was the main wear mechanism under dry friction, whereas abrasive is the main wear mechanism under oil lubrication. The changing wear mechanisms led to anti-wear variations in HDPEs with increasing MoS2 contents. The tribological properties were closely related to the crystallinity and thermo-mechanical properties of MoS2/HDPE. The samples with lower damping factors and better crystallinity showed better tribological properties. The excellent anti-wear properties of nano-spheres can be attributed to the deformation and exfoliation of nano-spheres in the friction process. Nano-platelets and nano-spheres in HDPE are advantageous under dry friction and oil lubrication, respectively. This study better elucidated the relationship between the property and morphology of MoS2 in a polymer.
    Tribology Letters 07/2012; 47(1). DOI:10.1007/s11249-012-9964-1 · 1.74 Impact Factor
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