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  • Articles  (47)
  • friction  (47)
  • Springer  (47)
  • American Chemical Society
  • 1995-1999  (47)
  • Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics  (47)
  • Architecture, Civil Engineering, Surveying
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  • Articles  (47)
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  • 1
    Electronic Resource
    Electronic Resource
    Unilateral problems of dynamics (1999)
    Springer
    Archive of applied mechanics 69 (1999), S. 503-527 
    Details
    ISSN: 1432-0681
    Keywords: Key words Unilateral contact ; multibody dynamics ; complementarity ; friction ; impact
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary Contact processes may be described by local discretizations, by rigid representation or by mixed methods incorporating both ideas. A rigid body approach is proposed for the dynamics of mechanical systems, achieving good results also for multiple-contact problems. Contacts in multibody systems are mainly considered, with the corresponding contact constraints varying with time, thus generating structure-variant systems. The equations of motion for dynamical systems with such unilateral behavior are discussed, solution methods and applications are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004190050240
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  • 2
    Electronic Resource
    Electronic Resource
    Numerical simulation of density distribution during compaction of iron powders (1997)
    Springer
    Archive of applied mechanics 67 (1997), S. 191-199 
    Details
    ISSN: 1432-0681
    Keywords: Key words powder metals ; compaction ; friction ; FE method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary The compaction process of iron powder is considered. Due to negligible elastic strains the rigid-plastic model is applied. A yield condition containing the first stress invariant is used. All material functions depend on the relative density of the powder, which changes during the compaction process. Siebel friction law is applied, and the friction factor is considered to be depending on the relative density. Various material functions are applied in the numerical simulation, and the results are compared with experimentally obtained data. The best fitting material functions and friction factors are obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004190050111
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  • 3
    Electronic Resource
    Electronic Resource
    Simulating discontinuous phenomena affecting robot motion (1996)
    Springer
    Journal of intelligent and robotic systems 15 (1996), S. 53-65 
    Details
    ISSN: 1573-0409
    Keywords: Simulation ; DAE systems ; friction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The paper deals with simulation of mechanical systems affected by discontinuous phenomena. These phenomena involve impulsive events and/or models whose structure changes depending on the values of some system variables. The models of three kinds of these discontinuities (joint with static friction, collisions with rigid environment, bifurcation behavior near kinematic singularities) are given, and a simulation environment, based on the DAE solver DASSL is presented, that also allows efficient simulation of sample-data systems. Some simulation results achieved with the proposed environment are finally presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00435727
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  • 4
    Electronic Resource
    Electronic Resource
    Molecular dynamics simulation of boundary lubricated interfaces (1999)
    Springer
    Journal of computer-aided materials design 6 (1999), S. 69-80 
    Details
    ISSN: 1573-4900
    Keywords: adsorption ; friction ; lubrication ; tribological system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A molecular dynamics simulation study of friction in boundary lubrication was conducted in order to investigate the atomic-scale behavior of lubricant molecules during sliding motion. The simulated system consisted of two silicon (001) semi-infinite substrates lubricated by a three-layer film of dodecane. Silicon was modeled using the Stillinger–Weber potential, and the dodecane with the Consistent Force Field function; a novel scheme was used to generate the silicon–dodecane interaction potentials. The simulations show that dodecane molecules strongly prefer to adsorb into the ledges on the silicon surface. The orientation of the adsorbed molecules depends, however, on the concentration of the lubricant at the surface, showing a tendency to stand up at high lubricant concentrations. In sliding, the dodecane layers adsorbed on the surfaces behave as a solid, whereas the middle layer exhibits liquid-like characteristics. The friction coefficient of this well-lubricated case was calculated to be 0.08.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008658828194
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  • 5
    Electronic Resource
    Electronic Resource
    Finite-element modelling of soil-geogrid interaction dealing with the pullout behaviour of geogrids (1998)
    Springer
    Acta mechanica Sinica 14 (1998), S. 371-382 
    Details
    ISSN: 1614-3116
    Keywords: sand, geogrid ; interaction ; two dimensional finite-element modelling ; plane-stress ; small pullout box ; pullout rig ; friction ; bearing resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A two dimensional plane-stress finite-element type of analysis is presented to predict the behaviour of geogrids embedded in sand under pullout loading conditions. In the analysis the interactions between soil and geogrid are simulated by non-linear springs. The stiffnesses of the springs can be determined from simple tests in a specially designed pullout box. The proposed finite element (FE) analysis is applied to interpret test results from a large scale pullout test rig. The predicted behaviour of the geogrid under pullout load agrees well with the observed data including the load-displacement properties, the displacement distribution along the longitudinal direction and the mobilisation of the frictional and bearing resistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02486875
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  • 6
    Electronic Resource
    Electronic Resource
    Surface Modification of Nitrile Rubber by Plasma Polymerization (1998)
    Springer
    Plasmas and polymers 3 (1998), S. 129-147 
    Details
    ISSN: 1572-8978
    Keywords: Plasma polymerization ; surface modification ; nitrile rubber ; vinylidene fluoride ; friction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Radio frequency plasma polymerization of vinylidene fluoride was used to modify the surface properties of nitrile rubber. The chemistry and frictional properties of the plasma films were characterized. FTIR transmission spectra and EDX analysis of plasma polymer films deposited on NaCl windows showed that the degree of fluorination of the plasma polymers increased as plasma power was increased from 25 to 50 W, and then decreased monotonically at higher powers. An estimation of the actual F/C ratio from EDX data indicated that the plasma polymer films contained approximately one fluorine atom for every 2–5 carbon atoms. Sliding friction tests on a Delrin countersurface showed that the coefficient of friction of the plasma treated rubbers was lower than untreated rubber, but slighly higher than rubber coated with silicone oil. Repetitive sliding friction testing showed that silicone oil treated samples had a longer lubricating lifetime than plasma treated samples. However, cyclic friction tests conducted with nitrile rubber o-rings yielded similar frictional behavior and lubricating lifetimes for silicone oil and plasma treatments. There was no correlation between chemical composition and the frictional and wear properties of the plasma films. Environmental scanning electron micrographs showed that the plasma films were brittle and tended to crack and flake off during wear testing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/B:PAPO.0000005943.19927.a8
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  • 7
    Electronic Resource
    Electronic Resource
    Friction properties of new porous carbon materials: Woodceramics (1995)
    Springer
    Journal of porous materials 2 (1995), S. 237-243 
    Details
    ISSN: 1573-4854
    Keywords: woodceramics ; porous carbon ; friction ; friction coefficient
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Woodceramics are new porous carbon materials obtained from wood or woody materials impregnated with phenol resin, and carbonized in a vacuum furnace at high temperature. Woodceramics have several superior characteristics from the viewpoints of engineering materials and ecological materials: they are hard and strong, have porous structure and low density, are made from natural resources, do not cause environmental pollution, and are cheap to manufacture. This paper describes the fundamental friction properties of Woodceramics in sliding contact with several materials. Woodceramics made of medium density fiberboard (MDF) and beech impregnated with phenol resin and carbonized in a vacuum furnace at 800°C and 2000°C were rubbed against alumina, silicon nitride, bearing steel and diamond by using a reciprocating friction apparatus. Experiments were carried out unlubricated in air, impregnated with base oil and in water, at several normal loads and sliding velocities. The following principal results were obtained: (1) The friction coefficient is around 0.15, under all three lubrication conditions; (2) The friction coefficient slightly decreases and then stays constant with increasing normal load; (3) The friction coefficient is not affected by sliding velocity; (4) Woodceramics have a good self-lubricity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00488114
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  • 8
    Electronic Resource
    Electronic Resource
    Waer of composite thin-walled structural elements with consideration of thermal effects (1999)
    Springer
    Mechanics of composite materials 35 (1999), S. 213-222 
    Details
    ISSN: 1573-8922
    Keywords: friction ; wear ; contact problem ; thermoelastic characteristics ; anisotropy of properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The contact problem on interaction of rigid stamps with anisotropic plates with regard to wear and the corresponding frictional heating is considered. The procedure developed is based on the reduction of the governing equation to a system of Volterra integral equations of the second kind. The numerical analysis allows us to study the effects of both the anisotropic thermoelastic characteristics of materials and the nature of the interaction of the contact-pair elements on the wear process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02257251
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  • 9
    Electronic Resource
    Electronic Resource
    The effects of methane-debris molecules on the frictional properties of diamond (1995)
    Springer
    Tribology letters 1 (1995), S. 109-119 
    Details
    ISSN: 1573-2711
    Keywords: friction ; wear ; diamond ; tribochemistry ; debris
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Molecular dynamics simulations have been used to examine the friction between two surfaces placed in sliding contact. These simulations show that the presence of methane-debris molecules squeezed between two hydrogen-terminated diamond (111) surfaces significantly reduces the friction compared to the same two surfaces in the absence of debris. These findings are in agreement with macroscopic experiments that have examined the friction of diamond on diamond in the presence of debris. In addition, the friction coefficients are significantly lower compared to the same system with methyl groups chemisorbed to one of the diamond surfaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00209766
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  • 10
    Electronic Resource
    Electronic Resource
    Surface chemistry-controlled tribological behavior of silicon and diamond (1996)
    Springer
    Tribology letters 2 (1996), S. 173-187 
    Details
    ISSN: 1573-2711
    Keywords: tribometry ; high temperature ; single-crystal silicon ; polycrystalline silicon ; vacuum ; surface chemistry ; dangling bonds ; reconstruction ; adsorbates ; friction ; wear
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract SEM tribometric experiments were performed with Si(100) vs. Si(100) interfaces in mode-rate vacuum to 850°C. The results are compared with similar tests previously completed with fine-cauliflowered PCD (PCDfcf) mated against itself, and polished C(100)-textured polycrystalline diamond (PCDC(100)) sliding against Si(100). All data agree with a hypothesis connecting the thermal desorption of adsorbates and wear with the generation of dangling bonds on the sliding surfaces. Linking of the counterfaces by the free radicals appears to be the main cause of high adhesion and friction. The high friction can be drastically reduced by dissociative chemisorption of certain passivating gaseous species condensing at sufficiently low surface temperatures. Strong circumstantial evidence continues to mount for the incremental reduction in high temperature friction being caused by surface reconstruction. Deconstruction of the sliding surfaces and the reemergence of high friction eventually occurs on discontinued heating, until the adsorbates chemisorb on the cooled surfaces. There, the friction drops to a level determined by the characteristic shear strength of the interfaces and the wear-induced increase in the real area of contact. The maximum friction measured at high temperatures in vacuum, indicative of the most intensive interaction of dangling bonds at the interface, scaled only approximately with the 1.8 times strength of the C-C versus the Si-Si bonds. The 1.6 experimental ratio is lower than the theoretical, reflecting the broad distribution of dangling bond energies (densities of surface trap states) for PCD and even for polished Si(100). The wear rate of Si(100) sliding against itself is about four-orders-of-magnitude higher (~ 2 × 10-12 m3/(Nm)) than that of unpolished PCDfcf vs. itself (4 × 10-16 m3/(Nm)) or rough and unpolished PCDC(100) wearing its polished version (8.5 × 10-16 m3/(Nm)).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00160974
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  • 11
    Electronic Resource
    Electronic Resource
    Triboelectrochemistry on a nanometre scale (1996)
    Springer
    Tribology letters 2 (1996), S. 287-312 
    Details
    ISSN: 1573-2711
    Keywords: AFM ; STM ; electrochemistry ; electrode potential ; friction ; iron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Atomic force microscopy was used to measure the spatial distribution of friction on iron electrodes under controlled electrode potentials in alkaline electrolytes. Electrochemical oxidation greatly decreased the mean friction values, which were further diminished by addition of octanoic acid, due to the anodic formation of iron oxide and octanoate phases, respectively. While the application of a potential step to oxidising conditions produced a relatively homogeneous spatial distribution of friction, potential cycling between oxidising and reducing conditions resulted in inhomogeneities at the 100 nm scale.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173134
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  • 12
    Electronic Resource
    Electronic Resource
    Energy dissipation in scanning force microscopy-friction on an atomic scale (1996)
    Springer
    Tribology letters 2 (1996), S. 327-343 
    Details
    ISSN: 1573-2711
    Keywords: friction ; nanotribology ; scanning force and friction microscopy ; stick-slip
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Stick-slip behaviour for a typical scanning force microscope setup operated in the wearless friction regime is modelled. Not only the deflection of the cantilever but also the local elastic deformation of tip and sample are taken into account. The combined effect of macroscopic spring and microscopic elastic deformation is a key feature to the scanning motion of the tip. Within this model, energy dissipation arises naturally due to mechanical instabilities either of the macroscopic cantilever or of the microscopic tip-sample contact. Our model reproduces all features of atomically resolved friction loops, which can be calculated from interatomic potentials. Moreover, a general scheme is introduced which allows the exact response of the tip-sample system to be calculated from the different interacting potentials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00156906
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  • 13
    Electronic Resource
    Electronic Resource
    The friction and wear behavior of 2-(n-alkyldithio)-benzimidazole as additives in liquid paraffin (1999)
    Springer
    Tribology letters 7 (1999), S. 27-30 
    Details
    ISSN: 1573-2711
    Keywords: wear ; friction ; lubrication ; XPS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Three 2-(n-alkyldithio)-benzimidazoles were synthesized. The friction and wear behavior of the synthetic compounds as additives in liquid paraffin were examined with a four-ball machine, with emphasis on revealing the relationship between the chain length of the additive and the friction-reducing ability and lubricating mechanism of the additives. The film formed by the additive during the sliding process was investigated by using X-ray photoelectron spectroscopy. It was found that the synthetic compounds as additives in liquid paraffin had good antiwear performance. The longer the chain length of the synthetic compound, the more stable or less volatile is the compound and the more effective it is in improving wear resistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019104916833
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  • 14
    Electronic Resource
    Electronic Resource
    Adhesion, deformation and friction for self‐assembled monolayers on Au and Si surfaces (1999)
    Springer
    Tribology letters 7 (1999), S. 103-107 
    Details
    ISSN: 1573-2711
    Keywords: friction ; self‐assembled monolayers ; hysteresis ; alkanethiols ; alkylsilanes ; nanoindentation ; IFM ; aging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Using interfacial force microscopy (IFM), we investigated the tribological behavior of hexadecanethiol monolayers on Au and films of octadecyltrichlorosilane (ODTS), perfluorodecyltrichlorosilane (PFTS) and dodecane on Si. We observe a strong correlation between hysteresis in a compression cycle (measured via nanoindentation) and friction. Additionally, we suggest that the amount of hysteresis and friction in each film is related to its detailed molecular structure, especially the degree of molecular packing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019109117742
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  • 15
    Electronic Resource
    Electronic Resource
    Adhesion and friction properties of hydrogenated amorphous carbon films measured by atomic force microscopy (1995)
    Springer
    Tribology letters 1 (1995), S. 233-246 
    Details
    ISSN: 1573-2711
    Keywords: atomic force microscopy ; adhesion ; friction ; amorphous carbon films ; hydrogen effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Atomic force microscopy has been used to measure adhesion and friction forces at the interface between an oxidized metal probe tip and amorphous carbon films of varying hydrogen contents (12.3–39.0 atomic percent hydrogen). The interface of an oxide surface and a hard carbon coating models the unlubricated head-disk interface of current hard disk products. Adhesion forces normalized by the radius of curvature of the contacting tip range from 1.09 to 8.53 N/m. Coefficients of friction values, measured as the slope of the friction versus load plot, range from 0.33 to 0.87. A trend of increasing adhesion forces and coefficients of friction is observed for increasing hydrogen content in the films. We attribute the increase in adhesion and friction to increases in the surface free energy of the carbon films with the incorporation of hydrogen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00209778
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  • 16
    Electronic Resource
    Electronic Resource
    Tribological behavior of polycrystalline and single-crystal silicon (1996)
    Springer
    Tribology letters 2 (1996), S. 355-373 
    Details
    ISSN: 1573-2711
    Keywords: tribometry ; single-crystal silicon ; Si(100) ; Si(111) ; polycrystalline diamond ; vacuum ; high temperature ; surface chemistry ; dangling bonds ; reconstruction ; adsorbates ; friction ; wear
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract SEM tribometric experiments were performed with polycrystalline silicon (poly-Si) vs. poly-Si and Si(111) vs. Si(111) interfaces in moderate vacuum to 850°C, complementing similar recent experiments on Si(100) vs. Si(100). All friction data agree with a hypothesis associating the wear- and thermal desorption-induced generation and cooling-induced adsorptive passivation of dangling bonds on the sliding surfaces with high and low adhesion and friction, respectively. Strong additional evidence is given for a surface re- and deconstruction-induced, temporary reduction in high temperature friction. The wear rate of the various Si vs. Si specimens (on the order of 10-12 m3 /(N m)) specific to the wide temperature range vacuum test regimen is about 104 times higher than that of unpolished PCD films sliding against themselves under multi-GPa unit loads and similar environmental conditions. In contrast, the characteristic load-carrying capacity of the high-wearing Si, regardless of its crystal structure, was found to be only ∼ 1 MPa. The wear mechanism of the various Si crystallinities was heavily influenced by the agglomeration and plowing of the wear debris particles trapped in the contact zone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00156908
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  • 17
    Electronic Resource
    Electronic Resource
    Friction force microscopy investigations of potassium halide surfaces in ultrahigh vacuum: structure, friction and surface modification (1998)
    Springer
    Tribology letters 5 (1998), S. 91-102 
    Details
    ISSN: 1573-2711
    Keywords: force microscopy ; alkali halide ; KCl ; KBr ; KF ; friction ; wear ; surface structure ; nanotribology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Friction force microscopy measurements on the vacuum‐cleaved (001) surfaces of KF, KCl and KBr have been carried out. All surfaces exhibit atomically flat terraces with monatomic steps aligned preferentially along low‐index lattice directions. Stick‐slip lateral forces with the lattice periodicity are observed on all surfaces. Tip‐sample contact creates higher friction domains on the terraces of all three materials. The structure, topography and degree of friction force contrast of these domains is material dependent. The dependence of friction upon load generally does not coincide with the behavior expected for an elastic contact. We propose that the observed domains result from surface structural changes created by low load tip‐sample contact on these relatively soft materials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019112901870
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  • 18
    Electronic Resource
    Electronic Resource
    The decomposition mechanisms of a perfluoropolyether at the head/disk interface of hard disk drives (1998)
    Springer
    Tribology letters 5 (1998), S. 203-209 
    Details
    ISSN: 1573-2711
    Keywords: perfluoropolyether ; ZDOL ; head/disk interface ; friction ; catalysis ; decomposition mechanisms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The decomposition mechanisms of a perfluoropolyether (ZDOL) at the head/disk interface under sliding friction conditions were studied using an ultra‐high vacuum tribometer equipped with a mass spectrometer. Chemical bonding theory was applied to analyze the decomposition process. For a carbon coated slider/CNx disk interface, the primary decomposed fragments are CFO and CF2O, caused by the friction decomposition and electron bombardment in the mass spectrometer. For an uncoated Al2O3–TiC slider/CNx contact, CF3 and C2F3 fragments appear in addition to CFO and CF2O, resulting from the catalytic reactions and friction decomposition, indicating that the decomposition mechanism associated with friction leads to the breaking of the main chain of ZDOL and forms CF2=O, which reacts with Al2O3 to produce AlF3, and the rapid catalytic decomposition of ZDOL on the AlF3 surface follows. Moreover, the effects of frictional heat, tribocharge, mechanical scission and Lewis acid catalytic action, generated in friction process, on the decomposition of ZDOL are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019145809139
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  • 19
    Electronic Resource
    Electronic Resource
    Tribological characterization of thin hard coatings by reciprocating sliding tests (1995)
    Springer
    Tribology letters 1 (1995), S. 265-276 
    Details
    ISSN: 1573-2711
    Keywords: coatings ; reciprocating sliding ; humidity ; friction ; wear
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Thin hard coatings on metal or ceramic surfaces offer a large spectrum of improvements of the friction and/or wear behaviour of tribosystems. The development of coatings and the tailoring of their properties require test methods providing information about their friction and wear behaviour. A new wear test standard (ASTM) is under development for the evaluation of friction and wear quantities for sliding motions using the reciprocating sliding mode. The applicability of this test method to coated specimens was checked by testing uncoated and coated steel specimens in contact with alumina balls, whereby lower loads were used than in the ASTM proposal for bulk materials. Additionally, the influence of the relative humidity of the surrounding air at room temperature on friction and wear results was examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00174254
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  • 20
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    Mechanical and tribological properties of amorphous carbon films (1998)
    Springer
    Tribology letters 5 (1998), S. 25-39 
    Details
    ISSN: 1573-2711
    Keywords: hydrogenated ; non‐hydrogenated ; amorphous carbon ; thin films ; friction ; wear ; lubrication ; environment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The mechanical and tribological properties of amorphous carbon films have been studied in more detail in recent years because these films (a) can be deposited near room temperature, thus allowing film deposition on common engineering alloys (i.e., aluminum and steel) without altering their mechanical properties, and (b) are smooth and conform to surface roughness of the substrate, thus requiring no post deposition processing. In addition, amorphous carbon films exhibit low unlubricated sliding friction in contact with steel and ceramics which is comparable to that of steel against steel in a lubricated contact. The wear resistance of these films is also better than Ti‐based hard coatings. Further improvement in film tribological properties can be achieved by modifying film chemical composition. Because of these attractive features, amorphous carbon films have been evaluated in several applications including automotive, electronic and biomedical engineering. However, environmental factors such as oxygen and humidity have been found to influence tribological properties significantly. This paper reviews the current understanding of the tribological properties of both hydrogenated and non‐hydrogenated amorphous carbon films, the mechanisms responsible for low friction coefficient and identifies areas that require further research.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019152515982
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  • 21
    Electronic Resource
    Electronic Resource
    Effect of pin specimen contact length in the sliding direction on tribological results of pin-on-disc tests (1998)
    Springer
    Tribology letters 4 (1998), S. 49-58 
    Details
    ISSN: 1573-2711
    Keywords: pin geometry ; contact length ; friction ; wear ; pin-on-disc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Tribological properties of a material depend on a wide range of parameters/conditions. While some of them are obvious, some are quite subtle. One of these subtle parameters has been identified and reported here. Under sliding conditions, whenever surface layers are formed due to the interaction at the sliding interface (e.g., tribochemical interaction), the resultant tribological response has been conjectured to depend upon the relative length of the pin, parallel to the sliding direction, with respect to the corresponding length of the disc track. The results obtained from the experiments reported in this paper as well as those reported by different researchers in the past, furnish evidence to support this conjecture. It can be considered as a general parameter because of this wide spectrum of applications. It is shown in this paper that this parameter helps in selecting the optimum contact geometry of the pin under various experimental conditions. This might reduce the observed scatter in tribological test results. Such a study leads to the conclusion that, for tribological testing, a square/rectangular contact configuration of pin is preferable to a circular one.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019122314648
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    Tribology of a polystyrene polymer film investigated with an AFM (1998)
    Springer
    Tribology letters 4 (1998), S. 75-80 
    Details
    ISSN: 1573-2711
    Keywords: polystyrene ; friction ; AFM ; LFM ; polymer disentanglement ; friction on polymers ; amorphous polymer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Sliding experiments were performed on polystyrene (PS) with a nanotip. Several molecular weights were investigated. The friction coefficients were found to be between 0.2 and 0.45, i.e., friction coefficients very close to the ones measured with a tribometer. Thus, in the case of these amorphous PS films, it appears that the friction coefficient is scale-independent. The velocity dependence was also investigated, but only slight effects, if any, were measured. The most striking effect was the variation of the force at which the tip unsticks during a sliding experiment as a function of the molecular weight. The available lowest externally applied force increases as the molecular weight decreases. Also, evidence of the influence of the M w on the coefficient of friction was observed. These results suggest that disentanglement of the macromolecules plays a role in describing the rupture of the contact.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019130516466
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    Frictional characteristics of ceramics under water‐lubricated conditions (1998)
    Springer
    Tribology letters 5 (1998), S. 303-308 
    Details
    ISSN: 1573-2711
    Keywords: ceramics ; water ; friction ; contact pressure ; sliding velocity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Friction experiments were conducted on four kinds of ceramics (SiC, Si3N4, Al2O3 and ZrO2) against themselves in water under different contact pressures and sliding velocities. The variations of friction coefficients as a function of sliding distance, and the effects of mean contact pressure and sliding velocity on friction coefficients were shown. Friction coefficients lower than 0.03 were observed under a certain combination of mean contact pressure and sliding velocity for each material. The friction coefficient suddenly increased when the mean contact pressure was above a threshold value, which depended on both sliding velocity and the material of sliding pairs. SiC had a higher threshold value than the other three ceramics at every sliding velocity investigated.
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    URL: http://dx.doi.org/10.1023/A:1019174615499
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    Atmospheric effects of friction, friction noise and wear with silicon and diamond. Part III. SEM tribometry of polycrystalline diamond in vacuum and hydrogen (1999)
    Springer
    Tribology letters 6 (1999), S. 103-112 
    Details
    ISSN: 1573-2711
    Keywords: polycrystalline diamond ; (100)-texture ; polishing ; tribometry ; vacuum ; hydrogen ; high temperatures ; friction ; friction noise ; noise reduction ; wear ; dangling bonds ; adsorbates ; desorption ; chemisorption ; re(de)construction ; tribocatalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In this part III of a multi-part paper series, the results of additional SEM tribometric experiments are described, performed with polished, mostly C(100)-oriented polycrystalline CVD diamond film [PCDC(100) vs. PCDC(100)] counterfaces sliding in $$\sim 1 \times 10^{ - 5}$$ Torr and in 0.1–0.3 Torr partial pressures of pure hydrogen gas. These tests were completed under a 28 g (0.27 N) normal load, under standard and slow thermal ramping conditions at temperatures ranging from room temperature to 1000°C. The friction data were examined per the computer logging and analysis techniques described in part I. The treatment of the data is similar to that of Si in part II: the maximum and the average coefficients of friction (MAX.COF and COF) and their ratios (the friction noise FN) are employed to measure possible lubricative interaction of the diamond surfaces with rarefied hydrogen. The results indicate that excited species of molecular hydrogen enter into tribothermally catalyzed reactions not only with Si but with PCDC(100) surfaces as well. Similar to the behavior of Si, the most beneficial friction-reducing regime occurs in a temperature range just before the thermal desorption of adsorbates. The general magnitudes of MAX.COF, COF and the FN are significantly lower than those of the Si crystallinities, in both vacuum and $$P_{{\text{H}}_{\text{2}} }$$ . The wear rate of the PCDC(100) film characteristic of the standard thermal ramping test procedure performed mostly in $$P_{{\text{H}}_{\text{2}} }$$ is around $$4 \times 10^{ - 16} {\text{m}}^3 /({\text{Nm)}}$$ , in good agreement with the wear rate previously measured in vacuum for unpolished, fine-cauliflowered diamond films. The data indicate that smooth polycrystalline diamond is a significantly better bearing material for miniaturized moving mechanical assembly applications than Si.
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    URL: http://dx.doi.org/10.1023/A:1019147304112
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    Friction‐generated surface deposits (1999)
    Springer
    Tribology letters 7 (1999), S. 129-135 
    Details
    ISSN: 1573-2711
    Keywords: friction polymers ; carbon ; selective transfer ; Raman spectroscopy ; magnetic storage media ; catalytic decomposition of hydrocarbons ; catalytic generation of hydrocarbons from carbon oxides ; polymers ; polytetrafluoroethylene ; perfluoropolyethers ; alumina–titania sliders ; exhaust gases ; boundary lubricants ; boundary lubrication ; silicon nitride ; boron carbide ; silicon carbide ; boric acid ; silicic acid ; surface chemistry ; transfer films ; friction ; lubrication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Recent publications are reviewed that illustrate friction and wear reductions by friction‐generated surface coatings in a number of applications. The emphasis is on surface chemistry. Topics included are the friction of polymers with and without fillers, the friction of metals and ceramics, friction and wear related to computer disk and tape drives, friction and wear reduction in atmospheres of carbonaceous gases, and chemical reactions between tribological surfaces with and without lubricants.
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    URL: http://dx.doi.org/10.1023/A:1019177505446
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    Normal and lateral modulation with a scanning force microscope, an analysis: implication in quantitative elastic and friction imaging (1999)
    Springer
    Tribology letters 7 (1999), S. 199-212 
    Details
    ISSN: 1573-2711
    Keywords: scanning force microscope ; lateral force microscope ; force modulation ; normal and lateral modulation ; elasticity ; friction ; contact stiffness ; Young modulus ; shear modulus ; modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Results and an analysis are presented on elastic and friction imaging by indirect force modulation with a scanning force microscope. Two techniques are compared, normal modulation (Z-modulation, perpendicular to the surface of the sample) and lateral modulation of the contact (X-modulation in the plane of the sample, perpendicular to the axis of the cantilever). Theoretical and experimental results show that lateral modulation offers great advantages compared to normal modulation: the images are free of artifacts and can be easily quantified.
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    URL: http://dx.doi.org/10.1023/A:1019142025011
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    A new calibration method of the lateral contact stiffness and lateral force using modulated lateral force microscopy (1999)
    Springer
    Tribology letters 7 (1999), S. 213-220 
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    ISSN: 1573-2711
    Keywords: scanning force microscopy ; lateral force modulation ; contact stiffness ; elasticity ; friction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract We describe a new calibration method for lateral contact stiffness using modulated lateral force microscopy, a technique that offers some advantages with respect to the more classical friction force microscopy currently used for characterizing the friction properties of materials. The calibration method is based on the study of the lateral contact stiffness versus applied load and on the use of elasticity contact theories to determine by fit the calibration coefficient, allowing the scaling of experimental data. The method is tested by measuring the friction coefficient and shear strength of silicon and mica samples, respectively, and compared with results from the literature.
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    URL: http://dx.doi.org/10.1023/A:1019150226828
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    Friction and slip of a simple liquid at a solid surface (1999)
    Springer
    Tribology letters 7 (1999), S. 147-152 
    Details
    ISSN: 1573-2711
    Keywords: slip ; lubrication ; friction ; lyophobic ; liquid–solid interface
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract We report a novel experimental technique using total internal reflection – fluorescence recovery after photobleaching (TIR‐FRAP) to probe the velocity of a liquid near a wall with a resolution of the order of 100 nm. As an example of use, we have investigated the boundary condition of the liquid velocity during lubricated friction and studied the influence of a classical additive (stearic acid) in a base oil (hexadecane), and demonstrate that simple Newtonian fluids can develop slip at the wall.
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    URL: http://dx.doi.org/10.1023/A:1019161101812
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    A study of 2-(n-alkyldithio)-benzoxazoles as novel additives (1999)
    Springer
    Tribology letters 7 (1999), S. 173-177 
    Details
    ISSN: 1573-2711
    Keywords: wear ; friction ; lubrication ; XPS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The syntheses of 2-(n-alkyldithio)-benzoxazoles are described. Their wear and friction performances are examined in liquid paraffin using a four-ball machine. The synthesized products have been found to exhibit appreciable antiwear capability. The effect of additive chain length on wear scar diameter and friction coefficient is investigated under different test conditions. The film formed by the additive during the sliding process was investigated by using X-ray photoelectron spectroscopy.
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    URL: http://dx.doi.org/10.1023/A:1019194009081
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    Friction and elasticity on a molecular scale (1995)
    Springer
    Tribology letters 1 (1995), S. 247-252 
    Details
    ISSN: 1573-2711
    Keywords: microscopy ; AFM ; SFM ; FFM ; friction ; elasticity ; anisotropy in friction ; cohesive energy ; molecular scale elasticity ; lipid film ; Langmuir-Blodgett films ; ultrathin films
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A molecular scale atomic force microscopy study of friction and elasticity is presented on a one-component lipid bilayer system - a model boundary lubricant. With a real area of contact on the order of the lattice spacings of the sample, the elastic compliances of single lipid molecules are recorded - the first report of a molecularly resolved elasticity map. The anisotropic and highly ordered structure of the lipid bilayer has been observed to cause contrast information in friction on molecularly flat areas, and to be dependent on the sliding direction. This anisotropic behavior of friction has been measured to be independent of normal elastic compliances. Only asymmetric indentation which causes in-plane compliances leads to heterogeneities in the elasticity map. In this fundamental study of friction, the effects of adhesion and elasticity are discussed.
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    URL: http://dx.doi.org/10.1007/BF00209779
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    Effect of surface contamination on the UHV tribological behavior of the Cu(111)/Cu(111) interface (1995)
    Springer
    Tribology letters 1 (1995), S. 201-210 
    Details
    ISSN: 1573-2711
    Keywords: friction ; adhesion ; ultrahigh vacuum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Friction and adhesion measurements have been made using two Cu(1 11) samples modified by the presence of atomic adsorbates. Copper surfaces with 10–15 Å thick contaminant films resulting from exposure to the atmosphere exhibited a static friction coefficient of μs = 0.75 ± 0.18. A sharp increase in the friction coefficient was observed when the contaminant layer was reduced to submonolayer thickness by sputtering and for the cleanest Cu(111) surfaces studied the static friction coefficient was μs = 4.4 ± 1.3. To further investigate the tribological effect of submonolayer coverages of surface contamination adhesion experiments were performed using surfaces modified with sulfur adsorbed at coverages in the range θs = 0.0–0.39 ML (saturation). The adhesion coefficient of the clean surfaces (μad = 0.69 ± 0.20) was markedly reduced by the presence of 0.05 ML of sulfur and decreased monotonically with increasing sulfur coverage to a limiting value of μad = 0.26 ± 0.07 at θs = 0.39.
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    URL: http://dx.doi.org/10.1007/BF00209774
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    Friction force microscopy as a probe of molecular relaxation on polymer surfaces (1995)
    Springer
    Tribology letters 1 (1995), S. 253-264 
    Details
    ISSN: 1573-2711
    Keywords: force microscopy ; friction ; relaxation ; glass ; gelatin ; polymer ; network
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The scan-velocity dependence of friction force microscopy (FFM) is characterized on nominally-dry gelatin films and related to the rate dependence of dissipative molecular relaxations. For a range of scanning-parameter values the measurement itself affects the frictional characteristics of the films: imparted frictional energy populates molecular conformations from which more dissipative relaxations occur. Variations in frictional dissipation tens of nanometers in lateral size are quantified as histograms of the number of image pixels versus frictional force. Histogram breadth and symmetry apparently reflect the energy dispersion of molecular relaxations.
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    URL: http://dx.doi.org/10.1007/BF00209780
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    Some stressing and environmental parameters related to phosphate-stearate coating performance in cold forging of steel (1996)
    Springer
    Tribology letters 2 (1996), S. 55-70 
    Details
    ISSN: 1573-2711
    Keywords: cold forging ; phosphate coating ; soap settling ; lubrication ; friction ; seizure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A friction-seizure test procedure is proposed to analyze phosphate/stearate coating performance in relation to stressing conditions. Test results, including the occurrence of hydrodynamic lubrication, mixed lubrication and seizure at the slider/specimen coated interface, are related to effective phosphate bonding and to lubricant reactive effects. The soap settling process is analyzed in terms of seizure sensitiveness and coating aging is studied in relation to moisture content and temperature. The effects of coating surface temperature on the occurrence of lubrication type and seizure are also analyzed for reactive and unreactive soaps. Stressing conditions such as sliding velocity and contact pressure are studied and a coating behaviour law for seizure is finally proposed.
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    URL: http://dx.doi.org/10.1007/BF00182548
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    A treatment of interfacial cracks in the presence of friction (1998)
    Springer
    International journal of fracture 94 (1998), S. 371-382 
    Details
    ISSN: 1573-2673
    Keywords: Interfacial cracks ; friction ; fracture toughness ; energy release rate fiber pull-out and push-out.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Frictional sliding on interface crack surfaces results in weak crack tip stress singularity and zero strain energy release rate. A fracture criterion based on finite extension strain energy release rate, is proposed to capture the intrinsic fracture toughness. The finite extension strain energy release rate is shown to represent the magnitude of the singular stress field. Numerical simulations of a center crack in a bimaterial infinite medium under remote shear as well as fiber pull-out and push-out in composite materials are presented to illustrate the frictional effect in both small and large scale contacts near the crack tip.
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    URL: http://dx.doi.org/10.1023/A:1007526830000
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    Surface chemistry-mechanical property relationship of low density polyethylene: an IR+visible sum frequency generation spectroscopy and atomic force microscopy study (1998)
    Springer
    Tribology letters 4 (1998), S. 231-235 
    Details
    ISSN: 1573-2711
    Keywords: sum frequency generation (SFG) ; vibrational spectroscopy ; atomic force microscopy (AFM) ; elastic modulus ; friction ; additives ; polyethylene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Surface-specific IR+visible sum frequency generation (SFG) spectroscopy was used to obtain chemical composition of two polymer surfaces. The SFG surface vibrational spectrum of pure low density polyethylene and that of a commercial sample of the same kind of polymer, which contains additives, are markedly different. This correlates well with the very different surface mechanical properties, i.e., stiffness (indicative of the elastic modulus) and friction, which were measured by atomic force microscopy (AFM) on the same polymer surfaces. The surface of CLDPE is dominated by methoxy (−OCH3) contained additives, segregated from the bulk, which explains a lower stiffness, adhesion and friction of the surface, as measured by AFM.
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    The respective role of oxygen and water vapor on the tribology of hydrogenated diamond-like carbon coatings (1998)
    Springer
    Tribology letters 4 (1998), S. 259-265 
    Details
    ISSN: 1573-2711
    Keywords: diamond-like carbon ; tribochemistry ; friction ; ultrahigh vacuum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The tribological behavior of diamond-like carbon coatings (DLC) strongly depends on the chemical nature of the test environment. The present study proposes to explore the influence of water vapor and oxygen on the friction behavior of a hydrogenated DLC coating exhibiting ultralow friction in ultrahigh vacuum (friction coefficient below 0.01). Using a UHV tribometer, reciprocating pin-on-flat friction tests were performed in progressively increasing or decreasing partial pressures of pure oxygen and pure water vapor. The maximum gaseous pressures of oxygen and water vapor were 60 hPa and 25 hPa (1 hPa = 100 Pa), respectively, the second value corresponding to a relative humidity (RH) of 100% at room temperature. It was found that, for the pressure range explored, oxygen does not change the ultralow friction behavior of DLC observed in UHV. Conversely, water vapor drastically changes the friction coefficient at pressures above 0.5 hPa (RH = 2%), from about 0.01 to more than 0.1. Electron energy loss spectroscopy and in situ Auger electron spectroscopy have been performed to elucidate the friction mechanisms responsible for the tribological behaviors observed with the two different gaseous environments. In all cases no significant oxidation has been observed either inside the wear scars or in the wear debris particles. Ultralow friction is systematically associated with a homogeneous carbon-based transfer film. The higher friction observed at partial pressure of water vapor higher than 0.5 hPa, is associated with a thinner transfer film. Consequently friction seems to be controlled by the transfer film whose kinetics of formation strongly depends on the partial pressure of water vapor.
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    Atmospheric effects of friction, friction noise and wear with silicon and diamond. Part II. SEM tribometry of silicon in vacuum and hydrogen (1999)
    Springer
    Tribology letters 6 (1999), S. 87-102 
    Details
    ISSN: 1573-2711
    Keywords: silicon ; tribometry ; vacuum ; hydrogen ; high temperatures ; friction ; friction noise ; noise reduction ; wear ; dangling bonds ; adsorbates ; desorption ; chemisorption ; re(de)construction ; tribothermal catalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Scanning electron microscope (SEM) tribometric data on polycrystalline silicon (poly-Si) vs. poly-Si, Si(100) vs. Si(100) and Si(111) vs. Si(111) interfaces, obtained in $$\sim 1 \times 10^{ - 5}$$ Torr and in 0.2 Torr partial pressure of hydrogen gas ( $$P_{{\text{H}}_{\text{2}} }$$ ) from room temperature to 850°C, were performed under standard and much slower thermal ramping rates. The friction data were analyzed per the methodology described in part I of this paper series. The results indicate a highly beneficial friction- and wear-reducing regime within a relatively narrow thermal region. This desirable region coincides with some chemisorption of excited species of molecular hydrogen just before the mass thermal desorption of surface hydrides. These data represent the tribochemical equivalent of a method routinely used in electronics, whereby deep electron traps (dangling Si bonds) are passivated by baking in molecular hydrogen. The $$P_{{\text{H}}_{\text{2}} }$$ also exerts a moderating influence on the size of the friction noise at all test temperatures. However, the general level of friction beyond the beneficial thermal region is high. In parallel, the general wear rate of Si representative of the entire range of standard thermal ramping in both atmospheric environments is in the extremely high 10-12m3/(N m) range. Operating strictly in the beneficial, low-friction thermal regime resulted in a several orders-of-magnitude reduction in the wear rate over those measured under standard thermal ramping conditions. Although the results confirm previous findings that Si is not a good material of construction for miniaturized moving mechanical assemblies (e.g., microbearings and gears), there seems to be some limited possibility of gas-phase lubrication of Si micromechanisms with rarefied hydrogen at surface temperatures between 100 and 300°C.
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    Effect of humidity on wear of M-50 steel with a branched perfluoropolyalkylether lubricant (1999)
    Springer
    Tribology letters 6 (1999), S. 123-127 
    Details
    ISSN: 1573-2711
    Keywords: perfluoropolyalkylether ; polyether ; PFPAE ; relative humidity ; friction ; wear ; Krytox
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Humidity is an uncontrolled variable in many tribology tests. This report shows that changes in relative humidity can affect wear for all perfluoropolyalkylethers regardless of their molecular structure. Using a Cameron–Plint tribometer under controlled environmental conditions, wear of M-50 steel with a Krytox (a branched perfluoropolyalkylether) lubricant was studied under boundary lubrication conditions at 150°C in air with relative humidity ranging from 1 to 95%. Both wear and friction decreased sharply as humidity was increased from 1 to 20%, then were constant as the humidity was increased to 95%. Thus, wear is highly dependent on humidity when relative humidity is less than 20%. The similar effect of humidity on wear previously observed for Fomblin Z, a linear perfluoropolyalkylether containing difluoroacetal groups, and Demnum S, a linear perfluoropolyalkylether which does not contain difluoroacetal groups, indicates that this may be a general property of all commercially available perfluoropolyalkylethers, branched as well as linear ones.
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    Tribological performance of PFPE and X-1P lubricants at head–disk interface. Part I. Experimental results (1999)
    Springer
    Tribology letters 6 (1999), S. 129-139 
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    ISSN: 1573-2711
    Keywords: lubricant ; friction ; wear ; degradation ; thin-film disks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract X-1P, a cyclic phosphazene lubricant, is studied and compared with polar perfluoropolyether (PFPE) lubricant Z-Dol. Contact angles of lubricants are measured on different solid surfaces. Contact start-stop (CSS), drag, and ball-on-flat tests are performed and the results are discussed. Drag tests under high vacuum are also performed and discussed. Experimental results show that lubricant X-1P exhibits lower static friction and higher durability than lubricant Z-Dol, especially at high humidity. Higher durability is also observed for X-1P under the high vacuum condition compared with lubricant Z-Dol. Diamond-like carbon (DLC) overcoat on the Al2O3–TiC slider surface lowers friction and prolongs durability, especially for lubricant Z-Dol at high humidity, whereas for X-1P, there is no benefit of DLC. X-1P as an additive shows some improvement in durability at high humidity as compared to lubricant Z-Dol.
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    UHV friction of tribofilms derived from metal dithiophosphates (1999)
    Springer
    Tribology letters 6 (1999), S. 171-179 
    Details
    ISSN: 1573-2711
    Keywords: Modtp ; Zndtp ; MoS2 ; selective transfer ; tribochemistry ; antiwear ; friction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The friction‐reduction mechanisms of Modtp and Zndtp were highlighted by submitting tribofilms to friction in ultra‐high vacuum (UHV). The use of an UHV tribometer to understand these phenomena is justified by the fact that the friction coefficient recorded in UHV is close to the friction coefficient obtained in traditional tests in oil. After UHV friction, the transfer films on the pin were analyzed by in situ AES, XPS and AES mapping. Low friction is associated with the transfer to the pin of a sulfur‐rich film. In the case of Modtp, we observe a very thin MoS2 film. The UHV friction coefficient approaches 0.04. In the case of Zndtp, the transfer film contains ZnS together with some phosphates. Because of the poor capacity of ZnS to reduce friction, the UHV friction coefficient recorded is near 0.15. A global model of the action of dithiophosphates in reducing friction is described on the basis of the hard and soft acids and bases (HSAB) principle.
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    Observation of proportionality between friction and contact area at the nanometer scale (1999)
    Springer
    Tribology letters 7 (1999), S. 73-78 
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    ISSN: 1573-2711
    Keywords: nanotribology ; friction ; contact area ; atomic force microscopy ; diamond ; tungsten carbide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The nanotribological properties of a hydrogen‐terminated diamond(111)/tungsten‐carbide interface have been studied using ultra‐high vacuum atomic force microscopy. Both friction and local contact conductance were measured as a function of applied load. The contact conductance experiments provide a direct and independent way of determining the contact area between the conductive tungsten‐carbide AFM tip and the doped diamond sample. We demonstrate that the friction force is directly proportional to the real area of contact at the nanometer‐scale. Furthermore, the relation between the contact area and load for this extremely hard heterocontact is found to be in excellent agreement with the Derjaguin–Müller–Toporov continuum mechanics model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019173404538
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    Friction and lubrication effects in the machining of aluminium alloys (1998)
    Springer
    Tribology letters 5 (1998), S. 117-122 
    Details
    ISSN: 1573-2711
    Keywords: machining ; metal cutting ; lubrication ; friction ; aluminium alloys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Friction between the rake face of a cutting tool and the freshly formed chip surface plays a vital role in influencing both the ease of cutting and the quality of the resultant machined surface. The existence of clean metallic surfaces together with the high local hydrostatic stresses favour the formation of strong adhesion between the cutting tool or insert and the machined component. These adhesive bonds can lead to poor surface integrity although their extent can be limited by the provision of a suitable machining lubricant. In an effort to identify the essential lubricating aspects of fluid activity, as opposed to any role as a coolant, experiments have been carried out involving the orthogonal machining of precipitation‐hardened aluminium alloys, principally Al 2014, in controlled, low‐pressure gas environments in which the feed (i.e., the depth of cut) speed and temperature have been varied while using a variety of tool materials and lubricating species. The results indicate that there can be unexpectedly subtle, but significant, interactions between the metallurgy of the workpiece, the nature of the surface of the tool and the surrounding environment. These are not wholly consistent with conventional theories of vapour phase lubrication in which transport of the lubricant has been assumed to control the effectiveness of the lubricating agent. The implications of these observations for the complex tribological system constituted by the combination of workpiece, tool surface and local environment are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019164918708
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    Microtribological studies of unlubricated sliding Si/Si contact in air using AFM/FFM (1996)
    Springer
    Tribology letters 2 (1996), S. 207-220 
    Details
    ISSN: 1573-2711
    Keywords: silicon ; friction ; pull-off forces ; capillary forces ; humidity effect ; AFM ; FFM ; surface topography ; microtribology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Tribological properties of Si/Si contacts were measured on a microscale by using an atomic force/friction force microscope. Friction forces and pull-off forces between a Si tip and a polished surface of a Si(100) wafer were studied as a function of applied normal load and relative humidity of the surrounding air. The results show that pull-off forces and friction coefficients increased and were strongly influenced by capillary forces with increasing humidity. Tribological interactions during 20 passes of overlapping sliding contact at 50% relative humidity and very small loads of 70 nN were confined to the layer of adsorbates and chemical reactions, without measurable solid damage on the Si(100) wafer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173127
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    Friction and wear of synthetic diamond with and without N+ implantation and CVD diamond coating in air, water and methanol (1996)
    Springer
    Tribology letters 2 (1996), S. 241-246 
    Details
    ISSN: 1573-2711
    Keywords: diamond ; tribology ; friction ; wear ; CVD ; ion implantation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The friction and wear of synthetic diamond with and without N+ implantation and CVD diamond coatings were studied in air, water and methanol. It was shown that water effectively reduced the friction of the synthetic diamond and CVD diamond at lighter loads, but methanol did not. Wear of the diamond was minimal in methanol. N+ ion implantation was less effective at reducing the friction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173130
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  • 45
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    Atmospheric effects of friction, friction noise and wear with silicon and diamond. Part I. Test methodology (1999)
    Springer
    Tribology letters 6 (1999), S. 79-86 
    Details
    ISSN: 1573-2711
    Keywords: SEM tribometry ; silicon ; polycrystalline diamond ; vacuum ; hydrogen ; high temperatures ; friction ; friction noise ; noise reduction ; data analysis ; characteristic frequency ; transducer ringing ; wear ; dangling bonds ; adsorbates ; desorption ; chemisorption ; re(de)construction ; tribothermal catalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This multi-part paper series gives evidence of tribothermally catalyzed, lubricative interactions of low partial pressures of hydrogen, water vapor and oxygen with silicon and polycrystalline diamond employed as bearing materials in moving mechanical assemblies (e.g., miniaturized rotors, bearings and gears) of microelectromechanical systems. In part I a test methodology is described, whereby wide environmental range SEM-tribometric friction data are combined with friction noise analysis and applicable literature information to further assist in interpreting atomic-level interactions governing the macroscopic friction and wear behavior of Si and diamond. To further correlate the wear- and thermal desorption-induced generation, re(de)construction and adsorbate-passivated annihilation of dangling σ bonds with high and low adhesion and friction, previously generated average coefficient of friction (COF) values are complemented with the concept of the associated MAX.COF: the highest coefficient of kinetic friction gleaned from the raw computer-logged friction force data of each oscillatory cycle of an experiment. The MAX.COF/COF ratios are used as measures of the friction noise as a function of temperature and atmospheric environment. These quantities, sampled at the appropriate data logging rate to circumvent test machine-related vibrational disturbances, demonstrated signs of friction- and friction noise-reducing gas-phase interactions of dry hydrogen with silicon (part II) and diamond (part III). Future installments will deal with similar lubricative properties of low partial pressures of wet hydrogen and dry oxygen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019151405021
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    Tribological performance of PFPE and X-1P lubricants at head–disk interface. Part II. Mechanisms (1999)
    Springer
    Tribology letters 6 (1999), S. 141-148 
    Details
    ISSN: 1573-2711
    Keywords: lubricant ; friction ; wear ; degradation mechanism ; thin-film disks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper, with the concepts of hydrogen bonding interaction and tribo-emission, develops a new approach of the mechanism of perfluoropolyether (PFPE) lubricant degradation at the head–disk interface. The role of lubricant X-1P in tribological performance is also described. The mechanism is as follows: (1) at the interface, there exist hydrogen atoms with partial positive charge and oxygen atoms with partial negative charge; (2) hydrogen bonding interactions at the sliding interface result in high friction which depletes the lubricant film at some sites; (3) low energy electrons are emitted from the sites with solid–solid asperity contact, inducing C–O bond scission through the interaction of low-energy electrons with PFPE lubricant molecules. Carbon overcoat on Al2O3–TiC surface passivates the interaction between water and PFPE lubricant molecules. Hydrogen bonding interactions are minimized during the presence of lubricant X-1P. The new approach well explains experimental results in part I of the paper.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019159606838
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    Computer simulation of sliding hydroxylated alumina surfaces (1999)
    Springer
    Tribology letters 7 (1999), S. 153-159 
    Details
    ISSN: 1573-2711
    Keywords: alumina ; sliding surfaces ; molecular dynamics simulations ; stick–slip sliding ; friction ; energy relaxation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A molecular dynamics simulation is performed to investigate the frictional force and energy transfer dynamics associated with sliding hydroxylated alumina surfaces. The calculated coefficient of friction is in good agreement with a recent experimental study. The dynamics of energy transfer from the interface of the sliding surface is investigated by calculating the surface–surface intermolecular potential and the energy in surface hydroxyl groups. The simulations indicate the experimental friction force arises from energy relaxation. A transition from stick–slip to smooth sliding is observed as the sliding velocity is increased.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019121420468
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