外文翻譯--mos2納米管的潤(rùn)滑機(jī)制表面粗糙度和磨合效果（英文）

1、See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/256914020Lubrication of DLC-coated surfaces with MoS2nanotubes in all lubrication regimes: Surfaceroughness an

2、d running-in effectsArticle in Wear · June 2013Impact Factor: 1.91 · DOI: 10.1016/j.wear.2013.03.033CITATIONS7READS443 authors, including:Mitjan KalinUniversity of Ljubljana149 PUBLICATIONS 1,749 CITATIONS

3、 SEE PROFILEAll in-text references underlined in blue are linked to publications on ResearchGate,letting you access and read them immediately.Available from: Mitjan KalinRetrieved on: 05 May 2016markedly influences the

4、lubrication effectiveness of the nano- tubes. While with the rough surfaces the performance changes less over time, i.e., after the running-in, the smooth DLC-coated surfaces lubricated with the nanotubes-containing oil

5、always provide the lowest friction. In order to explain the effect of the surface roughness in the nanoparticle-lubricated contacts (of any type of materials) we present this effect with a model based on a graphical, 2-d

6、imen- sional, actual 1:1 projection scale of the surface profiles, nanopar- ticles and film thickness.2. Experimental details2.1. MoS2 nanotubesMoS2 nanotubes with typical diameters below 100 nm and lengths up to 20 μm h

7、ave been synthesised by the sulphurization of Mo6S4I6 nanowires at 1073 K in a reactive gas composed of 98 vol% Ar, 1 vol% of H2S and 1 vol% of H2 running for 1 h [26]. During the sulphurization process the iodine was co

8、mpletely removed from the starting material and substituted by sulphur. X-ray powder diffraction and X-ray energy-dispersive analyses of the end product revealed an iodine-free MoS2 compound. The pristine MoS2 nanotubes

9、kept the original hedgehog self-assembly of the starting material (Fig. 1(a)), which can be easily dispersed in polar media using ultrasound. High-resolution studies revealed some dome-terminated ends of the tubes (Fig.

10、1(b)). The walls of the tubes are less than 10 nm thick. A relatively high concentration of structural defects is present in the form of sub-cylinders or parts of separated lamellas that are visible inside the nanotubes.

11、 It is reasonable to assume that these defects can influence the mechan- ical properties of the nanotubes, which can, as a consequence, be more easily exfoliated under shear stress.2.2. Tribological testsThe friction exp

12、eriments in which self-mated DLC/DLC contacts were used were performed at room temperature using a mini- traction machine, MTM (PCS Instruments, UK), with a ball-on-disc configuration. The tests employed a 19.05-mm (3/4-

13、inch) diameter ball and a 46-mm-diameter disc. The ball is loaded against the face of the disc and the ball and disc are driven independently to create the desired slide-to-roll ratio (SRR). The disc was immersed in a lu

14、bricant and all of the friction experiments were performed at a normal load of 35 N, which corresponds to a maximum Hertzian contact pressure of 1 GPa (a mean value of 0.7 GPa). For each sample a Stribeck curve (referred

15、 to as the ‘initial Stribeck’) was performed initially, with the mean contact velocity (also known as the entrainment velocity) decreasing from 3.2 m/s to 0.002 m/s (i.e., a transition from the elastohydrodynamic (EHL) t

16、o the boundary-lubrication regime) and with a SRR of 50%. Afterthe formation of the initial Stribeck curve, a long-duration (2 h) test was performed at a constant mean contact velocity of 0.05 m/ s. At the end of this lo

17、ng-term test, after the surfaces were run-in, another Stribeck curve (referred to as the ‘final Stribeck’) was performed under the same conditions as initially. Since the applied force and oil viscosity were kept constan

18、t, all the Stribeck curves can be given as a coefficient of friction that is a function of the mean contact velocity. The Stribeck curves for each test setup were acquired several times and representative measurements ar

19、e presented in the diagrams. The mini-traction machine was equipped with an interferome- try method to measure sub-micron additive films on the speci- mens as they form during the test. An optical interferometry measurem

20、ent is made ex-situ, immediately after stopping the tribological test. To perform the measurement the ball is loaded against the glass disc and an image of the complete contact area is taken with a high-resolution RGB ca

21、mera. The clean surface of the balls prior to the testing was firstly imaged for reference and then the balls were imaged after each Stribeck test.2.3. Material and lubricantsThe balls and the discs for the experiments w

22、ere made from AISI 52100/DIN 100Cr6 steel, both had a hardness of 760 HV0.1, measured with a micro-hardness tester (Leitz Miniload, Wild Leitz GmbH, Wetzlar, Germany). The DLC coating was deposited on both the balls and

23、the discs so that self-mated DLC/DLC contact pairs were obtained. The DLC coating was a commercially available coating produced by Sulzer Sorevi SAS (Limoges, France) using a plasma-assisted chemical vapour deposition (P

24、ACVD) process. The surface layer consisted of a non-doped, amorphous, hydrogenated DLC coating (a-C:H) with a thickness of 1.1 μm. The adhesion- promoting interlayer consisted of a-C:H:Si:O with a thickness of 0.6 μm. Th

25、e producer stated that the coating hardness was 23 GPa, its elastic modulus was 180 GPa and the hydrogen content was 30%. The arithmetical mean surface roughness, Ra, and the root- mean-square surface roughness, Rq, were

26、 measured with an AFM (CP-II, Veeco, New York, USA). The Ra and Rq of the balls were 0.010 μm and 0.012 μm, respectively. The experiments were per- formed with two sets of DLC-coated discs having different surface roughn

27、esses. The roughness parameters Ra and Rq for the smooth discs were 0.00670.0005 μm and 0.00870.0005 μm, respec- tively. For the rough discs the Ra value was 0.03670.003 μm and the Rq value was 0.08070.002 μm. The experi

28、ments were performed using polyalphaolephin (PAO) oil. According to the supplier (Neste Oil, Espoo, Finland) the kinematic viscosity of the oil is 29.0–30.5 mm2/s at 40 1C and 5.7–6.0 mm2/s at 100 1C. Some of the experim

29、ents were per- formed using the base PAO oil without any additives (denoted as ‘PAO’), while some of the experiments were conducted using theFig. 1. The MoS2 nanotubes: (a) SEM micrograph of hedgehog-like self-assemblies