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Book Applied Mechanics Reviews

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1994 with total page 1036 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Dynamic and Quasi static Contact and Scratch Analysis of Micro nanoscale Thin Solid Films with Application to Magnetic Storage Hard Disk Drives

Download or read book Dynamic and Quasi static Contact and Scratch Analysis of Micro nanoscale Thin Solid Films with Application to Magnetic Storage Hard Disk Drives written by Raja Ramakanth Katta and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: With current demand for decreased size of micro/nanoscale systems, coupled with increased mobility, critical understanding of the ensuing contact or impact related behavior of thin solid films used in these systems is of paramount importance for improved design and reliability. In modern micro/nanodevice technologies significant emphasis has to be placed on the design of thin-films which can provide the required contact and scratch resistance. To aid this endeavor, scientific studies of the contact and scratch processes in these systems, both static and dynamic are needed to provide the tools necessary to help the advancement of these technologies. One such problem is the impact contact or quasi-static contact and scratch of the slider and disk in magnetic storage hard disk drives (HDD). Similar contact problems are encountered during the operation of other micromechanical systems like RF-MEMS switches where surface damage is observed after cyclic contact. One of the most critical elements of multilayer contact analysis is proper determination of the nanomechanical properties of each thin-film on the multilayer system. In the first part of this work the method of determining the mechanical properties using the Oliver and Pharr (O-P) nanoindentation technique is described. For nanometer sized thin-films where the O-P technique gives incorrect results, an improved method is used. Later a dimensional analysis-based method to obtain the mechanical properties from the nanoindentation data is implemented for magnetic storage films. A direct comparison of the properties obtained from conventional O-P nanoindentation technique to this new technique is presented. In the second part of this work, the effect of dynamic contact or impact on multilayer thin films specific to magnetic storage hard disk drives is presented. Since there are no impact models available for multilayer thin films in the literature, a new contact mechanics-based (CM) semi-analytical model of a rigid sphere (representing a slider corner) impacting an elastic-plastic (E-P) multilayer thin-film half-space was proposed for the first time to examine the potential damage to a magnetic storage head disk interface (HDI). A dynamic 3D finite element analysis (FEA) model was also developed to examine the impact damage in more detail and validate the impact model. To characterize the plastic deformation and frictional energy losses associated with the impact damage, a comprehensive oblique elastic impact coefficient of restitution (COR) model was proposed for elastic-plastic impacts for the first time and validated using FEA. A method to decouple the oblique impact parameters into normal impact COR and tangential impact COR was formulated. Since, in microsystems, the geometry of the impacting bodies is not limited to spherical bodies, a new contact mechanics-based (CM) model of a rigid cylinder with a finite length impacting an elastic-plastic homogeneous disk was also proposed and includes a novel method of estimating the residual depth after impact. Based on elastic unloading, an improved coefficient of restitution model was also proposed. This new impact model was applied to study a practical case of a cylindrical feature on the slider of a magnetic storage hard disk drive impacting the disk to predict various critical impact contact parameters. The CM model was validated using a plane strain FEA-based model and it was found that a cylindrical feature with longer length results in a substantial alleviation of impact damage. The final part of this work involved the investigation of the performance of thin-film multilayers while under the influence of much milder quasi-static contact scratch. A 2D plane strain FEA model of a rigid cylinder sliding over a multilayered thin-film half space was developed. The effects of different contact parameters such as applied normal load, friction coefficient and radius of curvature of the cylinder on the critical stresses in the multilayer system were analyzed. Later, for direct experimental comparison a full-blown 3D quasi-static FEA-based nanoscratch model of the multilayer thin-film system was also developed. The FEA scratch results were compared to nanoscratch experiments performed on actual magnetic disks. Consequently, the 3D FEA scratch model was used to quantitatively correlate the subsurface plastic deformation to the magnetic erasures typically found in HDDs due to scratch for the very first time.

Book Tribology and Mechanics of Magnetic Storage Devices

Download or read book Tribology and Mechanics of Magnetic Storage Devices written by Bharat Bhushan and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 1035 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetic recording is presently a $50 billion industry. It spans audio, video, and digi tal applications in the form of tapes and disks. The industry is expected to grow by a factor of five or more in the next decade. This growth will be accompanied by dramatic improvements in the technology, and the potential exists for magnetic-recording den sities to improve by at least one order of magnitude! Magnetic-recording process is accomplished by relative motion between a mag netic head and a magnetic medium. Types of magnetic media for digital recording are: flexible media (tapes and floppy disks) and rigid disks. Physical contact between head and medium occurs during starts and stops and hydrodynamic air film develops at high speeds. Hying heights (mean separation between head and medium) are on the order of 0. 1 micrometer comparable to surface roughness of the mating members. Need for higher and higher recording densities requires that surfaces be as smooth as possible and flying heights be as low as possible. Smoother surfaces lead to increased static/ kinetic friction and wear. In the case of magnetic tapes, in order to have high bit capac ity for a given size of a spool, we like to use as thin a tape substrate as possible. Thinner tapes are prone to local or bulk viscoelastic deformation during storage. This may lead to variations in head-tape separations resulting in problems in data reliability.

Book Friction and Wear Micromechanisms of Carbon coated Thin film Magnetic Rigid Disks and Application of Ion Beam Technology in Head media Tribology

Download or read book Friction and Wear Micromechanisms of Carbon coated Thin film Magnetic Rigid Disks and Application of Ion Beam Technology in Head media Tribology written by Bo Wei and published by . This book was released on 1994 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Metals Abstracts

Download or read book Metals Abstracts written by and published by . This book was released on 1998 with total page 1076 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Tribological Behaviour of Ti Based Thin Films

Download or read book Tribological Behaviour of Ti Based Thin Films written by Aslihan Sayilan and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The nature of interface in contact with skin, clothes or joints is one of the prime interests in the field of metallic biosensors. This interface can be enhanced through PVD processes in terms of chemistry and microstructure. Furthermore, dynamic evaluation of the contact interface at the early stage is essential to better understand the wear mechanism and to anticipate the efficient service life of the corresponding bio-device. Therefore, within this thesis, a laboratory-made micro-tribometer was developed and presented. This particular reciprocating ball-on-disk stage is coupled with an environmental SEM (eSEM) to characterise, at small scale, the tribological behaviour of the system under realistic in situ conditions. To express the proof of concept, a preliminary analysis was performed with a conventional TiN PVD hard coatings, used as a model surface. The testing procedure for the dynamic approach during the run-in period throughout 100 cycles was defined in the controlled atmosphere in eSEM chamber (both in high vacuum and 50% relative humidity (RH)). When the tribological tests were performed, the wear track of the films was examined in situ after every 10 cycles, while the ball track was analysed in post mortem mode. Once validated, the mini-tribometer stage was applied for a more realistic metal used in biosensor systems: titanium. Indeed, this metal presents a high biocompatible character, coupled with interesting mechanical properties. The wear character of pure Ti film is still an issue, due to its columnar microstructure, which can be modified with an addition of proper alloying elements. In this sense, silver is an outstanding material to be alloyed with titanium for bio-sensor applications regarding its anti-bacterial character and ductile nature, as well its remarkable sliding behaviour in nanoparticle form. Within this thesis, Ti-Ag films were deposited with magnetron sputtering PVD process with several Ag contents. Various types of multiscale characterization (microstructural, chemical, electrical, mechanical) were performed to analyse the effect of Ag in the film composition. It was shown that increasing Ag content led to a denser microstructure with Ag-based nano-/micro-meter sized clusters distributed into the film matrix. Moreover, from a functional point of view, it also provided a slight improvement on hardness, Young's modulus and electrical conductivity of the films. During the in situ tribological analysis, the small-scale strategy of characterization that was specifically developed in this PhD, has highlighted a strong influence of the contact environment on its tribological behaviour. In particular, the effect of the humidity rate of the contact region on the tribological behaviour was deeply investigated, and the effect of Ag content on tribological behaviour of Ti-Ag films was studied. It was seen that temperature change to modify the humidity affects the tribological behaviour of polymer counter-face and Ag.

Book Ultrathin Carbon Based Overcoats for Extremely High Density Magnetic Recording

Download or read book Ultrathin Carbon Based Overcoats for Extremely High Density Magnetic Recording written by Reuben Jueyuan Yeo and published by Springer. This book was released on 2017-07-03 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the latest research in ultrathin carbon-based protective overcoats for high areal density magnetic data storage systems, with a particular focus on hard disk drives (HDDs) and tape drives. These findings shed new light on how the microstructure and interfacial chemistry of these sub-20 nm overcoats can be engineered at the nanoscale regime to obtain enhanced properties for wear, thermal and corrosion protection – which are critical for such applications. Readers will also be provided with fresh experimental insights into the suitability of graphene as an atomically-thin overcoat for HDD media. The easy readability of this book will appeal to a wide audience, ranging from non-specialists with a general interest in the field to scientists and industry professionals directly involved in thin film and coatings research.

Book An Acoustic Emission Study of the Wear Mechanisms of Magnetic Oxide Rigid Disks

Download or read book An Acoustic Emission Study of the Wear Mechanisms of Magnetic Oxide Rigid Disks written by Matthew Mark Besen and published by . This book was released on 1988 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Digests of Intermag

Download or read book Digests of Intermag written by and published by . This book was released on 1998 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Tribology of Contact near contact Recording for Ultra High Density Magnetic Storage

Download or read book Tribology of Contact near contact Recording for Ultra High Density Magnetic Storage written by C. Singh Bhatia and published by . This book was released on 1996 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: These eight papers focus on fundamental issues related to tribology of the head/media interface in magnetic storage devices. The papers address scientific challenges which will enable higher area storage densities through closer spacing between the head/disk interface. These challenges include under