The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
This paper outlines a procedure for the calibration of the lateral force applied to a triangular cantilever tip by means of a lateral force microscope. The force is directed perpendicular to the cantilever major axis. The lateral force results in a torsion of the cantilever. The torsion signal is monitored as a voltage on a four-sector photodiode. The conversion from a torsion signal to a lateral...
Impressive strides have recently been made in the field of tribology through molecular dynamics (MD) simulations. A convergence of MD and experiment has led to optimism in scientific circles that the mechanisms of friction and boundary lubrication, studied for centuries, can soon be understood and predicted by first principles. However, from the engineering point of view, practical predictive ability...
Previously we showed that the abrasiveness of a coating is closely related to its hardness. In the present work we use a ball-on-disk apparatus to examine the abrasive characteristics of a tungsten-containing diamondlike carbon coating and a metal-free diamondlike carbon coating deposited on steel coupons. We find that roughness with horizontal dimensions on the nanometer-scale is strongly correlated...
Atomic force microscopy/friction force microscopy (AFM/FFM) techniques are increasingly used for tribological studies of engineering surfaces at scales ranging from atomic and molecular to microscales. These techniques have been used to study surface roughness, adhesion, friction, scratching/wear, indentation, detection of material transfer, and boundary lubrication and for nanofabrication/nanomachining...
A theory is firstly developed of the noncontact friction forces between the sliding nanoasperity and substrate. The linear force-velocity dependence is substantiated. We differ two principally distinct types of the friction forces: the static force, independent of the tip velocity V, being of adhesive nature, and the dynamical one, proportional to V. Several mechanisms have shown to contribute the...
Fe-N/Ti-N magnetic multilayers with different thickness of Fe-N layers were deposited on Si (111) wafer by using magnetron sputtering technique. For comparison, Fe-N and Ti-N thin films were also prepared under the same conditions. Microhardness and reduced modulus of the multilayer were measured by using a nanoindenter with a diamond tip in conjunction with an atomic force microscope (AFM). Microfriction...
A thin water film present on surfaces plays a central role in defining the micro- and nanotribological properties of a system. This paper presents a quantitative examination of the nanotribological effects of thin water films in ultra high vacuum (UHV) on OH-terminated (hydrophilic) and bare (no OH terminations, hydrophobic in vacuum) silicon oxide surfaces. Water film thickness was controlled by...
In this paper, the effect of surface topography on the frictional behavior is investigated at micro/nano-scale in order to better understand the influence of asperity contact angle on friction. Experiments were performed to observe the variation in the frictional force as a spherical ball slides across a grooved surface. Specimens with single and multiple grooves of tens of micrometers in width were...
The nanotribological properties of amorphous carbon (a-C) films of thickness in the range of 5-85nm sputtered on Si(100) substrates were investigated with a surface force microscope (SFM), using a Berkovich diamond tip of nominal radius of curvature approximately equal to 200nm and contact (normal) loads between 10 and 1200μN. The dependence of the friction and wear behaviors of the a-C films on normal...
The recent emergence and proliferation of proximal probes, in particular scanning probe microscopies (the scanning tunneling microscope and the atomic force microscope), the surface force apparatus, and of computational techniques for simulating tip-surface interactions and interfacial properties, have led to the appearance of the new field of nanotribology, which pertains to experimental and theoretical...
A molecular dynamics simulation is used to investigate the effect of surface roughness on the nano-rheology of ultra-thin films confined between two solid walls. The results show that friction is sensitive to the confining surface morphology and the fluid molecules near the two confining surfaces are in a layering solid-like structure. At a high shear rate, the interfacial layers of the film stick...
A new rapid method of nano-scale wear testing was applied to a matrix of 150nm amorphous C and Cr doped amorphous C coatings in order to investigate a nano-wear process under conditions which are applicable to MEMS and similar devices. The nano-wear test involved adding a method of controlled oscillation to the sample mounting of a nanoindentation system utilising a spherical ruby counter-body. At...
A sample oscillation module linked to a nanoindentation unit was used to perform nano-scale wear testing on a series of sputtered Cr doped amorphous C films deposited over a range of thicknesses (10, 20, 50, 150, and 2000nm) under conditions relevant to MEMS and micro-scale engineering devices. A ruby sphere was used as the counter-body. Specific wear rates (defined as volume of worn material per...
With an atomic force microscopy, the tangential nanofretting behaviors of monocrystalline silicon (100) were investigated by using spherical diamond tips under atmosphere and vacuum conditions, respectively. Different from fretting, the nanofretting damage of silicon may successively experience two progresses, the generation of hillocks and grooves, with the increase in normal load. The critical contact...
We studied the wear behavior of gold (Au) and silver (Ag) against a single crystal silicon (Si) within a highly localized area. The nanowear was generated at the tip of an atomic force microscope (AFM) and was chemically activated by Si during sliding. AFM tips were coated with gold or silver thin films. During experiments, the coated AFM tip slided against the surface of a Si wafer. It was found...
A nanoscale study of the abrasive wear behaviour of a ductile monophasic metallic alloy (the stainless steel AISI 316L) is presented. By using atomic force microscopy (AFM) based techniques, particularly a diamond tip mounted on a stiff steel cantilever, the contact of a single abrasive asperity was simulated, and it was possible to determine accurately the load threshold below which no measurable...
The cross-sections formed by the contact asperities of two rough surfaces at an interference are actually island-shaped, rather than having the commonly assumed circular or elliptic contour. These island-shaped contact area contours show fractal behavior with fractal dimension D s of the two-dimensional profile. The three-dimensional surface fractal dimension for the topography of asperity...
We introduce a technique for measuring wear on the nano-scale by combining friction force and dynamic force microscopy. By measuring the resonance frequency of the cantilever after scratching over a sample surface we are able to detect the increase or decrease of the tip’s worn mass down to some picograms. Applying a recently developed technique to attach a small sphere to the upper end of the cantilever’s...
Using an atomic force microscope, the friction-induced hillocks of 0.5–7.1nm in height were observed on Si(100) surface under both atmosphere and vacuum conditions. Larger hillocks can be produced by either higher loads or more scratch cycles. Detailed surface analyses on the hillocks revealed that the thickness of oxidation layer formed during scratching was 1.2nm in vacuum and 1.5nm in atmosphere,...
A molecular dynamic simulation result is obtained for a nanoscale sliding layer system, with an emphasis on lattice structural changes and temperature variation induced by friction. A model for a stationary and moving layer of aluminum is analyzed at different sliding speeds. The model shows that the average temperature of the molecular structure increases rapidly during the transient period. The...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.