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1.
In this study, nanomachining is utilized to investigate the abrasive wear mechanism that produces a nano scale groove on a
bulk material. Two different tools (Berkovich and Conical) with the same tip radius (100 nm) but different edge geometries
were used for machining both Cu- and Ni-coated materials with a nanoindenter that was equipped with a nano scratching attachment.
It was found that the generated forces (normal and cutting) increased with the increase of depth of cut; however, the generated
normal force at the minimum depth of cut (50 nm) was more than the critical force for all machining conditions. Therefore,
at the minimum depth of cut, groove formation started with the ploughing mode of abrasive wear mechanism, then the cutting
mechanism activated along with the ploughing mechanism above a 100 nm depth of cut. The percentage values of these two mechanisms
were determined and utilized to determine the dominant mode of the abrasive wear mechanism for producing a nano scale groove
on a metal surface and, to correlate this, abrasive wear mechanism with the co-efficient of friction (μ) at different machining conditions. The results also showed that the co-efficient of friction (μ) increased when ploughing was the dominant mode of abrasive wear mechanism to produce a nano scale groove. Thus, μ was found to be proportional to the ploughing mode of abrasive wear mechanism in nanomachining. 相似文献
2.
Adhesion and friction studies of a nano-textured surface produced by spin coating of colloidal silica nanoparticle solution 总被引:1,自引:0,他引:1
This paper presents the results of adhesion and friction studies on a nano-textured surface. The nano-textures were produced
by spin coating colloidal silica nanoparticle solution on a flat silicon substrate. Surface morphology was characterized by
environmental scanning electron microscopy (ESEM) and scanning probe microscopy (SPM). Adhesion and friction studies were
conducted using a TriboIndenter employing diamond tips with 5 μm and 100 μm nominal radii of curvature. The results show that
the adhesion forces and coefficients of friction of the nano-textured surface measured by the 100 μm tip were reduced up to
98 and 88%, respectively, compared to those of a baseline silicon oxide film surface. 相似文献
3.
Miki Nakano Koji Miyake Atsushi Korenaga Shinya Sasaki Yasuhisa Ando 《Tribology Letters》2009,35(2):133-139
The tribological properties of patterned surfaces were investigated under lubricated conditions. Micropatterns were fabricated
on a Si surface using a combination of photolithography and plasma etching. NiFe film with a 150 nm thickness was then deposited
on the patterned Si surface. We prepared four kinds of patterned surfaces: dimple, grating, bump, and mesh patterns. The dimensions
of the patterns were: size 30–40 μm, pitch 120 μm, and depth 10–12 μm. Friction tests were carried out using a pin-on-plate
tribometer. The pin specimen was made of cast iron and had a flat end. The normal load was varied from 9.8 to 98 mN, and the
average sliding speed from 1.0 to 5.0 mm s−1. Slideway lubricating oils or a gear oil were used as the lubricant, and the ISO viscosity grades of these oils were VG32,
VG68, and VG320. The results showed that the friction coefficients of the two reverse patterns showed very similar tendencies
and that circular patterns had a lower friction coefficient than did the rectangular patterns at a high bearing characteristic
number. The surface geometry of the Si surface did not affect the friction coefficients at a low bearing characteristic number. 相似文献
4.
The substrate protection and self-healing capability of a cationic polymer lubricant (CPL) on a silicon oxide surface were
tested with a pin-on-disc tribometer and atomic force microscopy (AFM). CPL was made of low molecular weight polydimethylsiloxane
(PDMS) containing covalently attached quaternary ammonium cations and iodide counter-anions. CPL was spin-coated on the silicon
oxide surface to form a 3–4 nm thick bound-and-mobile lubricant layer. The CPL film capable of binding to the SiO2 surface through ionic interactions is superior in substrate protection than the neutral PDMS film which cannot form the bound
layer. The mobile component in the CPL film readily flows into the lubricant-depleted sliding contact region from the surrounding
film. The self-healing capability of CPL via lateral flow is slightly enhanced in humid environments due to water uptake in
the film. The 3–4 nm thick CPL film on silicon oxide takes 30–40 s to flow into a ~50 μm wide track, which corresponds to
an apparent spreading rate of 2–3 × 10−11 m2/s. 相似文献
5.
Nicolas Argibay James H. Keith Brandon A. Krick D. W. Hahn Gerald R. Bourne W. Gregory Sawyer 《Tribology Letters》2010,40(1):3-9
Following the pioneering work of Prof. James Lauer, the ability to provide continuous solid lubrication through vapor phase
delivery of carbonaceous gases has been successfully demonstrated on a pin-on-disk contact at the temperatures of 650 °C.
Results from tribological experiments under 2 N normal load and 50 mm/s sliding speed showed an over 20× reduction in friction
coefficient. The samples were silicon nitride (pin) versus CMSX-4 (disk) and the experiments when run in a nitrogen environment
with acetylene admixtures. Two repeat experiments gave average friction coefficients of μ = 0.03 and μ = 0.02. The process
was robust and provided low friction for the entire 500 m of sliding. Using focused ion-beam milling, high-resolution transmission
electron microscopy, and confocal Raman spectroscopy, the resulting solid lubricant was found to be oriented microcrystalline
graphite. 相似文献
6.
Friction and wear on PbS(100) surfaces have been investigated on the atomic scale as a function of temperature with atomic
force microscopy. At room temperature and above, the PbS(100) surface exhibited low friction (μ < 0.05) in contact with a silicon nitride probe tip, provided that interfacial wear was not encountered. In the absence of
wear, friction increased exponentially with decreasing temperature, transitioning to an athermal behavior near 200 K. An Arrhenius
analysis of the temperature dependence of friction yielded an activation energy ∆E = 0.32 ± 0.02 eV for the sliding contact of a silicon nitride tip on PbS(100). 相似文献
7.
Yasuhisa Ando Yosuke Inoue Kazuo Kakuta Takashi Igari Shigeyuki Mori 《Tribology Letters》2007,27(1):13-20
The effects of a self-assembled monolayer (SAM) coating on the friction and pull-off forces were determined by using two-dimensional
asperity arrays on silicon wafers. The arrays were coated with SAM composed of one of five different alkylchlorsilanes. First,
two-dimensional asperity arrays were created by using a focussed ion beam (FIB) system to mill patterns on silicon plates.
Each silicon plate had different patterns of equally spaced asperities. Each pattern (5 × 5 μm2) had a different radius of curvature of the asperity peaks, ranging from about 200 to 2500 nm. Then, each silicon plate was
immersed in a solution of a different alkylchlorsilane in hexane (either hexyltrichlorosilane, octyltrichlorosilane, dodecyltrichlorosilane,
tetradecyltrichlorosilane, or octadecyltrichlorosilane), thus coating the asperity arrays with SAM. The friction and pull-off
forces on the SAM-coated arrays were measured by using an atomic force microscope (AFM) that had a square flat probe. The
pull-off force for SAM-coated silicon was roughly proportional to the radius of curvature of the asperity peaks. The magnitude
of the pull-off force corresponded approximately to the capillary force calculated by using the contact angle of water on
the surface of SAM. The friction coefficient correlated with the inverse of the alkyl-chain length of the SAM. 相似文献
8.
N.P. Hung Y.Q. Fu 《The International Journal of Advanced Manufacturing Technology》2000,16(12):871-876
This paper investigates the effect of crystallographic orientation in ductile-regime (DR) machining of (100) silicon wafers.
Single crystalline diamond tools with 10-40 nm edge sharpness were used to machine the wafers at either constant depths of
cut, or a taper mode to vary the depths of cut up to 1<<<:956>>>m. The feedrates were normalised as percentages of tool nose
radii, and the machining process was performed using an ultraprecision machining system. The surface and subsurface integrity
were then characterised with an atomic force microscope, a phase shift interferomter, and an ion beam system. The measured
surface roughness of silicon was compared with those of copper alloys, and the calculated values.
A ductile-regime was achieved when machining along the <110> directions when the maximum chip thickness of less than 05 χm.
Machining conditions that formed thicker chips led to pitting, microcracks and slip lines. Such defects, which could be more
than 1 χm deep, were found along the <110> directions and occasionally along the <100> directions. Surface roughness below
10nm was measured in a DR areas, but was as high as 170nm in pitted areas. When the depth of cut was of the magnitude of the
tool edge sharpness, the surface finish was degraded by radial cracks in the lateral plane owing to rubbing between the tool
and the workpiece. The surface finish of the silicon, therefore, was rougher than that of copper alloys that were machined
using similar parameters. 相似文献
9.
The effect of surface textures on the friction of a poly(dimethylsiloxane) (PDMS) elastomer has been investigated at both
macro and microscales using a nanoindentation-scratching system. Friction tests were conducted by a stainless-steel bearing
ball with a diameter of 1.6 mm (macroscale tests) and a Rockwell diamond tip with a radius of curvature of 25 μm (microscale
tests) under normal loads of 5, 10, and 25 mN and with a sliding speed of 1 μm/s. Coefficient of friction (COF) on the pillar-textured
surface was found to be much lower than that on the smooth surface of the same material, and it was reduced by about 59% at
the macroscale tests and 38% at the microscale tests. The reduction of COF can be attributed to the reduced contact areas.
The use of the JKR model revealed that the adhesion force has less effect on contacts under higher normal loads. COFs in different
sliding directions on the groove-textured surfaces were compared, and a friction anisotropic behavior was identified and analyzed. 相似文献
10.
Nanotribological properties of NbSe2 are studied using an atomic friction force microscope. The friction force is measured as a function of normal load and scan
speeds ranging from 10 nm s−1 to 40 μm s−1 under two atmospheres (air and argon). At low speed, no effect of atmosphere is noticed and a linear relationship between
the friction and normal forces is observed leading to a friction coefficient close to 0.02 for both atmospheres. At high speed,
the tip/surface contact obeys the JKR theory and the tribological properties are atmosphere dependent: the shear stress measured
in air environment is three times lower than the one measured under argon atmosphere. A special attention is paid to interpret
these results through numerical data obtained from a simple athermal model based on Tomlinson approach. 相似文献
11.
In the present work, the effect of grain size on the friction and wear behavior of a copper (Cu) samples under different lubricant
conditions was studied. The structural evolution of Cu subsurface layers under friction in different lubricant conditions
was considered. All friction tests were conducted under laboratory conditions using a block-on-ring rig. The effects of sliding velocity and load on the friction coefficient and wear rate of Cu with different grain size (1, 30,
and 60 μm) were analyzed. The Cu samples with the average grain size of 1 μm were obtained due to severe plastic deformation
(SPD) by equal channel angular pressing (ECAP). The Stribeck curves for Cu samples with different virgin grain sizes were
considered. Elasto-hydrodynamic lubrication (EHL) and boundary lubrication (BL) regions were mainly studied in the present
work. Similar Stribeck curves were found out for Cu samples with different virgin grain size. A load of the transition from
the EHL to BL region was increased with a decrease of the grain size. While the friction coefficients were similar in the
EHL and BL regions for the samples with different grain sizes, the wear rate was increased remarkably with an increase the
virgin grain size. Flow localization during friction in the BL region led to formation of the vortex structure in subsurface
layers. Based on the dependence of the microhardness upon the depth, the degree of hardening (H) was evaluated. A correlation between the coefficient of wear and the deformation hardening of Cu samples with different
virgin grain sizes was revealed. In order to take into account the effect of the grain size and to predict the Stribeck curve,
a parameter, K, as the ratio between hardness of tested and annealed samples, was incorporated into the lubricant number. The theoretical
values of the Stribeck curve calculated for preliminary deformed Cu samples (d = 1 μm) and annealed samples (d = 60 μm) were well coincided with the experimental results. 相似文献
12.
13.
We study the friction, wear, and aging of a model boundary lubricant, an alkoxy monolayer covalently bonded to a Si(111) surface,
using an interfacial force microscope with a spherical diamond probe. The robust alkoxy bond creates a film that effectively
lubricates and prevents wear of Si at stresses comparable to those found in microelectromechanical systems devices. Sliding
on the monolayer over 50 nm produced friction approximately three times greater than that of sliding over molecular length
scales (∼2 nm); this is attributed to deformation dynamics of the experiment. By repeated scanning over the same location,
we observed wear on a level that reduces the friction by thinning and/or reordering the monolayer film. 相似文献
14.
On the Use of Calcium Fluoride as an Infrared-Transparent First Body for In Situ Temperature Measurements in Sliding Contact 总被引:1,自引:0,他引:1
This article presents an investigation of the temperature changes in dry sliding contact for braking applications. An original
metrology method was developed using a special pad with a calcium fluoride ‘window’ in its centre. As calcium fluoride is
transparent to infrared radiation (up to 92% in 1–5 μm spectra), it allows access to the disc surface during friction for
estimating its temperature using a two-colour pyrometer. Using this set-up, the surface temperature of the disc was successfully
determined during friction. In addition, the temperature in the contact area was compared to that measured immediately outside
the contact area; the difference between them proved to be very minimal (<5%). The effect of introducing a calcium fluoride
‘window’ on friction was also studied, and the results show that its use does not affect the friction coefficient. Finally,
the wear mechanisms of the calcium fluoride were studied through the characterisation of the worn surfaces using several techniques. 相似文献
15.
Zhao Qingliang Brinksmeier Ekkard Riemer Oltmann Rickens Kai 《Frontiers of Mechanical Engineering in China》2007,2(3):350-355
In this paper, a novel conditioning technique using copper bonded diamond grinding wheels of 91 μm grain size and electrolytic
in-process dressing (ELID) is first developed to precisely and effectively condition a nickel-electroplated monolayer coarse-grained
diamond grinding wheel of 151 μm grain size. Under optimised conditioning parameters, the super abrasive diamond wheel was
well conditioned in terms of a minimized run-out error and flattened diamond grain surfaces of constant peripheral envelope.
The conditioning force was monitored by a force transducer, while the modified wheel surface status was in-situ monitored
by a coaxial optical distance measurement system. Finally, the grinding experiment on BK7 was conducted using the well-conditioned
wheel with the corresponding surface morphology and subsurface damage measured by atomic force microscope (AFM) and scanning
electric microscope (SEM), respectively. The experimental result shows that the newly developed conditioning technique is
applicable and feasible to ductile grinding optical glass featuring nano scale surface roughness, indicating the potential
of super abrasive diamond wheels in ductile machining brittle materials.
__________
Translated from Chinese Journal of Mechanical Engineering, 2006, 42(10): 95–101 [译自: 机械工程学报] 相似文献
16.
The friction behavior of two different materials, mica and ultra-high molecular weight polyethylene (UHMWPE), was evaluated
at the nanoscale with an atomic force microscope and with a custom-built ball-on-flat microtribometer at the microscale. The
same counterface (Si3N4 probe), environmental conditions (25 °C, RH < 10%), and similar load ranges were maintained for all experiments. The friction-force
data obtained were analyzed for contact-area dependence. Friction force between silicon nitride and mica at the nanoscale
showed initial non-linearity with normal load up to a certain load, beyond which surface damage was observed resulting in
a linear dependence of friction force on normal load. At the microscale, the friction force of the mica–silicon nitride interface
exhibited linear dependence on normal load. Friction force between silicon nitride and UHMWPE exhibited non-linearity with
normal load at both the length scales, for the applied load ranges of our experiment. An appropriate contact mechanics theory
was applied to calculate an interfacial shear strength value for the material pair at both the scales. The values at both
the scales were similar, when the conditions were carefully maintained to be the same across scales. 相似文献
17.
A dynamic tribometer has been successfully developed utilizing torsional Kolsky bar (TKB) technique for tribo pairs subjected
to dynamic compression and shear. The dynamic tribometric responses of ground finish (R
a
= 0.17 μm) and polished finish (R
a
= 0.10 μm) surfaces of silicon carbide (SiC) under compression loading up to 1.5 GPa and shear-sliding velocity to 3.8 m/s
have been measured. The experimental results show Coulomb friction behavior. Hardening of shear response is found on both
the ground and polished surfaces. Repeating tests on the same tribo-pair demonstrate that steady state shear response on polished
surfaces can be achieved by cumulating shear-sliding distance. SEM observation of the tested surface shows that the tested
surfaces are microscopically shear-damaged. The similar surface conditions after a relative longer shear-sliding distance
on polished surfaces lead to the same steady state frictional coefficient, 0.61, for both finishing surfaces. 相似文献
18.
This article presents the results of nanoscale friction and adhesion of nanoparticle-textured surfaces (NPTS) using atomic
force microscope (AFM). The effects of coverage ratio, texture height, and packing density on the adhesion and friction of
the NPTS were investigated. The nano-textured surfaces were produced by self-assembling Au nanoparticles (NPs) with diameters
of 20 nm and 50 nm on the silicon (100) surfaces, respectively. Surface morphology of the NPTS was characterized by field
emission scanning electron microscopy and AFM. The results show that the NPTS significantly reduced the adhesive force compared
to the smooth surface. The adhesion of NPTS is mainly dependent on the coverage ratio of NPs rather than the texture height
and higher coverage ratio resulted in smaller adhesive force. The reduced adhesion of textured surfaces was attributed to
the reduced real area of contact. The friction of NPTS is mainly dependent on the spacing between asperities. The lowered
frictional force was obtained when the spacing between asperities is less than the size of AFM tip, because of the effectively
reduced real area of contact between the AFM tip and the NPTS surface. 相似文献
19.
A review of focused ion beam sputtering 总被引:1,自引:0,他引:1
Mohammad Yeakub Ali Wayne Hung Fu Yongqi 《International Journal of Precision Engineering and Manufacturing》2010,11(1):157-170
This paper reviews the applications of focused ion beam (FIB) sputtering for micro/nano fabrication. Basic principles of FIB
were briefly discussed, and then empirical and fundamental models for sputtering yield, material removal rate, and surface
roughness were presented and compared. The empirical models were more useful for application compared to fundamental models.
Fabrication of various micro and nano structures was discussed. Trimmed atomic force microscope (AFM) tips were tested in
measurement and imaging of high aspect ratio nanopillars where higher accuracy and clarity were observed. Micromilling tool
fabricated using FIB sputtering was used to machine microchannels. Slicing and dwell time control approaches on FIB sputtering
were presented for the fabrication of three dimensional microcavities. The first approach is preferred for practical applications.
The maximum aspect ratio of 13:1 of the microstructures was achieved. The minimum size of the nanopore was in the range of
2–10 μm. Cavities of microgear of 70 μm outside diameter were sputtered with submicrometer accuracy and 2–5 nm average surface
roughness. The microcavities were then filled with polymer in a subsequent micromodling process. The replicated microcomponents
were inspected with scanning electron microscope where faithful duplication of accuracy and surface texture of the cavity
was observed. 相似文献
20.
This article deals with the tribology of lipid coatings that resemble those found on human skin. In order to simulate the
lipidic surface chemistry of human skin, an artificial sebum formulation that closely resembles human sebum was spray-coated
onto mechanical skin models in physiologically relevant concentrations (5–100 μg/cm2). Water contact angles and surface free energies (SFEs) showed that model surfaces with ≤25 μg/cm2 lipids appropriately mimic the physico-chemical properties of dry, sebum-poor skin regions. In friction experiments with
a steel ball, lipid-coated model surfaces demonstrated lubrication effects over a wide range of sliding velocities and normal
loads. In friction measurements on model surfaces as a function of lipid-film thickness, a clear minimum in the friction coefficient
(COF) was observed in the case of hydrophilic, high-SFE materials (steel, glass), with the lowest COF (≈0.5) against skin
model surfaces being found at 25 μg/cm2 lipids. For hydrophobic, low-SFE polymers, the COF was considerably lower (0.4 for PP, 0.16 for PTFE) and relatively independent
of the lipid amount, indicating that both the mechanical and surface-chemical properties of the sliders strongly influence
the friction behaviour of the skin-model surfaces. Lipid-coated skin models might be a valuable tool not only for tribologists
but also for cosmetic chemists, in that they allow the objective study of friction, adhesion and wetting behaviour of liquids
and emulsions on simulated skin-surface conditions. 相似文献