Download or read book Atomic Scale Friction and Microfriction of Graphite and Diamond Using Friction Force Microscopy written by and published by . This book was released on 1993 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: Friction of graphite and diamond surfaces against a sharp silicon nitride tip was measured using a friction force microscope (FFM). Atomic-scale friction of a freshly cleaved highly oriented pyrolytic graphite (HOPG) exhibited the same periodicity as that of corresponding topography. However, the peaks in friction and those in corresponding topography profiles were displaced relative to each other. Using Fourier expansion of the interaction potential, we have calculated interatomic forces between the FFM tip and graphite surface. We have shown that the variations in atomic-scale friction and the observed displacement between the peaks in friction and those in corresponding topography can be explained by the variations in interatomic forces in the normal and lateral directions. At large scan sizes (50 nm x 50 nm or larger), the variation of friction for graphite and a single-crystal (IIa) diamond was found to follow the local slope of the sample surface, suggesting that a ratchet mechanism is operative in microscale friction.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 818 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Atomic Scale Friction Measurements Using Friction Force Microscopy Part 2 Application to Magnetic Media written by and published by . This book was released on 1993 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atomic Force/Friction Force Microscopes (AFM/FFM) were used to study tribological properties of metal-particle tapes with two roughnesses, Co-gamma Fe2O3 tapes (unwiped and wiped), and unlubricated and lubricated thin-film magnetic rigid disks (as-polished and standard textured). Nanoindentation studies showed that the hardness of the tapes through the magnetic coating is not uniform. These results are consistent with the fact that the tape surface is a composite and is not homogeneous. Nanoscratch experiments performed on magnetic tapes using silicon nitride tips revealed that deformation and displacement of tape surface material occurred after one pass under light loads (approx. 100 nN). A comparison between friction force profiles and the corresponding surface roughness profiles of all samples tested shows a poor correlation between localized values of friction and surface roughness. Detailed studies of friction and surface profiles demonstrate an excellent correlation between localized variation of the slope of the surface roughness along the sliding direction and the localized variation of friction. Atomic-scale friction in magnetic media and natural diamond appears to be due to adhesive and ratchet (roughness) mechanisms. Directionality in the local variation of atomic-scale friction data was observed as the samples were scanned in either direction, resulting from the scanning direction and the anisotropy in the surface topography. Atomic-scale coefficient of friction is generally found to be smaller than the macro coefficient of friction as there may be less ploughing contribution in atomic-scale measurements.
Download or read book The Atomic scale Origins of Friction written by Rachel J. Cannara and published by . This book was released on 2006 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamental Studies of Friction Lubrication and Wear by Atomic Force Microscopy written by and published by . This book was released on 1993 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: To probe friction, lubrication, and wear on an atomic scale, a capacitance-based ultrahigh vacuum force microscope was developed. It measures both parallel and perpendicular forces between a tip and a surface. Friction between a diamond tip and chemical-vapor-deposited (CVD) diamond films at loads below one micronewton showed a sublinear dependence of friction on load, with the effective friction coefficient varying between 0.2 and 0.8 depending on load and location. Stick-slip behavior resulting from both surface heterogeneity and static/dynamic friction was observed. A CVD process was developed for growing single crystal diamond tips with radii as small as 30 nm. The normal force between these tips and diamond (100) and (111) surfaces agrees with calculated dispersion forces. The frictional force variation on the (100) surface are tentatively associated with a reconstructed geometry convoluted over an asymmetric tip shape, while the (111) surface exhibits features which cannot be simply associated with the surface structure. Friction is approximately 3 nanonewtons independent of loads up to 100 nanonewtons. A field emission technique was developed for continuously observing the motion of individual adsorbed atoms and molecules. The hopping of individual Cs atoms between sites on a tungsten tip was observed with 2 ps and 5 Angstrom resolution.
Download or read book Atomic Scale Friction Measurements Using Friction Force Microscopy Part 1 General Principles and New Measurement Techniques written by and published by . This book was released on 1993 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Friction force measurements using modified atomic force microscopy, called here Friction Force Microscopy (FFM), are becoming increasingly important in the understanding of fundamental mechanisms of friction, wear, and lubrication, and to study interfacial phenomena in micro- and nanostructures used in magnetic storage systems and Microelectromechanical Systems (MEMS). FFMs can be used to study engineering surfaces in dry or wet conditions. A review of existing designs of FFMs and methods of friction force measurements is presented. In terms of friction force measurements, there are important issues related to the basic operation and calibration of these instruments which have not been fully studied. A new method of measuring friction fore using a commercial FFM and a calibration Procedure for conversion of measured data to normal and friction forces are presented. Microscale friction data of selected materials are presented and discussed in light of macrofriction measurements.
Download or read book Atomic scale Friction and Superlubricity written by Martin Dienwiebel and published by . This book was released on 2003 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Atomic Scale Friction Measurements Using Friction Force Microscopy Part II Application to Magnetic Media written by and published by . This book was released on 1993 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atomic Force/Friction Force Microscopes (AFM/FFM) were used to study tribological properties of metal-particle tapes with two roughnesses, Co gamma Fe2O3 tapes (unwiped and wiped), and unlubricated and lubricated thin-film magnetic rigid disks (as-polished and standard textured). Nanoindentation studies showed that the hardness of the tapes through the magnetic coating is not uniform. These results are consistent with the fact that the tape surface is a composite and is not homogeneous. Nanoscratch experiments performed on magnetic tapes using silicon nitride tips revealed that deformation and displacement of tape surface material occurred after one pass under light loads approx. 100 nN). A comparison between friction force profiles and the corresponding surface roughness profiles of all samples tested shows a poor correlation between localized values of friction and surface roughness.
Download or read book Tribology Issues and Opportunities in MEMS written by Bharat Bhushan and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 652 pages. Available in PDF, EPUB and Kindle. Book excerpt: Micro Electro Mechanical Systems (MEMS) is already about a billion dollars a year industry and is growing rapidly. So far major emphasis has been placed on the fabrication processes for various devices. There are serious issues related to tribology, mechanics, surfacechemistry and materials science in the operationand manufacturingof many MEMS devices and these issues are preventing an even faster commercialization. Very little is understood about tribology and mechanical properties on micro- to nanoscales of the materials used in the construction of MEMS devices. The MEMS community needs to be exposed to the state-of-the-artoftribology and vice versa. Fundamental understanding of friction/stiction, wear and the role of surface contamination and environmental debris in micro devices is required. There are significantadhesion, friction and wear issues in manufacturing and actual use, facing the MEMS industry. Very little is understood about the tribology of bulk silicon and polysilicon films used in the construction ofthese microdevices. These issues are based on surface phenomenaand cannotbe scaled down linearly and these become increasingly important with the small size of the devices. Continuum theory breaks down in the analyses, e. g. in fluid flow of micro-scale devices. Mechanical properties ofpolysilicon and other films are not well characterized. Roughness optimization can help in tribological improvements. Monolayers of lubricants and other materials need to be developed for ultra-low friction and near zero wear. Hard coatings and ion implantation techniques hold promise.
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1994 with total page 708 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Surface Coatings Technology written by B. D. Sartwell and published by Elsevier. This book was released on 2016-06-03 with total page 981 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface & Coatings Technology, Volume 61 presents the proceeding of the 20th International Conference on Metallurgical Coatings and Thin Films, held in San Diego, California, on April 19–23, 1993. This book discusses a variety of topics related to surface and coatings technology, including coatings for use at high temperature, hard coatings, and vapor deposition technology. Organized into 141 chapters, this compilation of papers begins with an overview of the coating requirements for long-life bucket protection, how each of these coating systems has performed, and the advantages and disadvantages of each. This text then discusses the gradient-free transition step achieved in the element analysis of the depth profiles. Other chapters consider the metastable yttrium oxide films that are synthesized using reactive sputter deposition. This book discusses as well the use of appropriate copper-based alloy coatings on structural components. The final chapter deals with the particle mechanical and thermal behavior in the process of high velocity oxy-fuel spraying. This book is a valuable resource for chemical engineers and metallurgists.
Download or read book Proceedings of the 7th ASME NDE Topical Conference written by Corinne Darvennes and published by . This book was released on 2001 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Friction and Mechanical Characterization on Nanoscale Using Atomic friction Force Microscopy written by Ashok V. Kulkarni and published by . This book was released on 1996 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ASME Technical Papers written by and published by . This book was released on with total page 506 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paper written by and published by . This book was released on 1993 with total page 502 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government reports annual index written by and published by . This book was released on 199? with total page 1216 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Sliding Friction at the Nanoscale written by Antoine Laine and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this manuscript, we use methodes inherited from Atomic Force Microscopy in order to measure the nanoscale mechanical response of different systems. The focus is put on highlighting the frictional response and dissipation mechanisms taking place at the single asperity level, where soft and hard condensed matter meet.We first present the development of a new experimental tool allowing nanorheology and nanotribology measurement in controlled environment. The study of mechanical properties of nanoconfined RTILs with this apparatus revealed the glassy nature of these dense electrolytes at metallic interfaces.We then study the dissipation phenomena at the ultimate scale for metallic nanojunctions made of a few atoms. The absence of defects rationalizes their unexpected mechanical properties in striking difference with the macroscopic realm.In fine, we focus on the dynamics of a metallic interface made of a few atoms and develop new experimental strategies to probe the frictional response of the interface under harmonic applied stress. Our measurements are quantitatively reproduced numerically and reveal an atomic-scale quantized slip friction mechanism.
