Author: Hong LiPublisher:
ISBN:
Category :
Languages : en
Pages : 306
Book Description
Study of Tribological Behaviour of Thin-film Magnetic Hard Disks Using Scratch Tests and Acoustic Emission
Author: Hong LiDeposition, Characterization and Tribological/magnetic Studies of Diamond-like Carbon and Magnetic Thin Films
Author: Geng WangApplied Mechanics Reviews
Author: Dynamic and Quasi-static Contact and Scratch Analysis of Micro-nanoscale Thin Solid Films with Application to Magnetic Storage Hard Disk Drives
Author: Raja Ramakanth KattaPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
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.
The Preparation, Characterization and Tribological Study of RF Sputtered Thin Films for Magnetic Memory Disk
Author: Chengyea LeuEnvironmental Effects on the Friction, Wear and Durability of Thin-film Magnetic Hard Disks
Author: Kathryn Jean WahlPublisher:
ISBN:
Category : Magnetic recorders and recording
Languages : en
Pages : 166
Book Description
Tribology and Mechanics of Magnetic Storage Devices
Author: Bharat BhushanPublisher: Springer Science & Business Media
ISBN: 1468403354
Category : Technology & Engineering
Languages : en
Pages : 1035
Book Description
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.
Metals Abstracts
Author: Experimental and Numerical Investigations of the Magnetic Head/tape Interface
Author: Sanwu TanPublisher:
ISBN:
Category : Magnetic recorders and recording
Languages : en
Pages : 450
Book Description
Author: Tse-an Yeh