The performance and durability of advanced, high temperature foil air bearings are evaluated under a wide range (10-50 kPa) of loads at temperatures from 25 to 650 deg C. The bearings are made from uncoated nickel based superalloy foils. The foil surface experiences sliding contact with the shaft during initial start/stop operation. To reduce friction and wear, the solid lubricant coating, PS 304, is applied to the shaft by plasma spraying. PS304 is a NiCr based Cr2O3 coating with silver and barium fluoride/calcium fluoride solid lubricant additions. The results show that the bearings provide lives well in excess of 30,000 cycles under all of the conditions tested. Several bearings exhibited lives in excess of 100,000 cycles. Wear is a linear function of the bearing load. The excellent performance measured in this study suggests that these bearings and the PS 304 coating are well suited for advanced high temperature, oil-free turbomachinery applications.

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.

This fully updated Second Edition provides the reader with the solid understanding of tribology which is essential to engineers involved in the design of, and ensuring the reliability of, machine parts and systems. It moves from basic theory to practice, examining tribology from the integrated viewpoint of mechanical engineering, mechanics, and materials science. It offers detailed coverage of the mechanisms of material wear, friction, and all of the major lubrication techniques - liquids, solids, and gases - and examines a wide range of both traditional and state-of-the-art applications. For this edition, the author has included updates on friction, wear and lubrication, as well as completely revised material including the latest breakthroughs in tribology at the nano- and micro- level and a revised introduction to nanotechnology. Also included is a new chapter on the emerging field of green tribology and biomimetics.