Mario Marchetti
Glenn Research Center
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Featured researches published by Mario Marchetti.
Tribology Letters | 2003
Michael J. Dube; Dennis Bollea; R William JonesJr.; Mario Marchetti; Mark J. Jansen
Synthetic hydrocarbon liquid lubricants (based on polyalphaolefins) have been developed for use in space applications. These materials have been fully characterized and their physical properties reported which include: kinematic and absolute viscosity, viscosity index, vapor pressure, evaporation, specific gravity, pour point, coefficient of thermal expansion, refractive index, and flow activation energy. In addition, tribological properties under ultrahigh vacuum conditions have been determined. These include: lubricated lifetimes using a spiral orbit tribometer (SOT) and vacuum four-ball wear rates. These values are compared to existing state-of-the-art space lubricants.
Tribology Letters | 2002
Mario Marchetti; R William JonesJr.; Kenneth W. Street; Donald R. Wheeler; Duane Dixon; Mark J. Jansen; Hiroshi Kimura
Commercial greases for space applications usually fulfill the requirements imposed by the severe conditions of use (load, ultrahigh vacuum, speed, etc.). The main requirement is their ability to create an elastohydrodynamic lubrication film, boundary film, or both, for the speed, load, and temperature conditions under which the mechanisms will operate. Three greases, all based on a multiply alkylated cyclopentane (Pennzane®) base oil, were studied. The thickeners were an n-octadecylterephthalamate soap, a lithium soap, and a urea derivative. A four-ball tribometer and a spiral-orbit tribometer were employed to evaluate the greases under ultrahigh vacuum. The results indicated that all three greases yielded very low wear rates and extended lifetimes. In addition, routine physical property data are reported for each grease.
Tribology Transactions | 2003
Mario Marchetti; William R. Jones; Stephen V. Pepper; Mark J. Jansen; Roamer E. Predmore
Many of todays spaceraft have long mission lifetimes. Whatever the lubrication method selected, the initial lubricant charge is required to last the entire mission. Fluid lubricant losses are mainly due to evaporation, tribo-degradation, and oil creep out of the tribological regions. In the past, several techniques were developed to maintain the appropriate amount of oil in the system. They were based on oil reservoirs (cartridges, impregnated porous parts), barrier films, and labyrinth seals. Nevertheless, all these systems have had limited success or have not established a proven record for space missions. The system reported here provides to the ball-race contact fresh lubricant in-situ and on demand when the ball bearing is close to failure. The lubricant is stored in a porous cartridge attached to the inner or the outer ring of a ball bearing. The oil is released by heating the cartridge to eject oil, taking advantage of the greater thermal expansion of the oil compared to the porous network. The heating may be activated by torque increases that signal the depletion of oil in the contact. The low surface tension of the oil compared to the ball bearing material is utilized and the close proximity of the cartridge to the moving balls allows the lubricant to reach the ball-race contacts. This oil re-supply system avoided a mechanism failure, reduced torque to an acceptable level, and extended the life of the component.
Tribology Letters | 2004
Kenneth W. Street; Mario Marchetti; R.L. Vander Wal; Aaron J. Tomasek
Lubrication Engineering | 2002
Mario Marchetti; Jacques Sicre; William R. Jones
NLGI spokesman | 2001
Mario Marchetti; William R. Jones; Kenneth W. Street; Stephen V. Pepper; Mark J. Jansen
Archive | 2003
Kenneth W. Street; Mario Marchetti; Randy L. Vander Wal; Aaron J. Tomasek
Archive | 2002
Clifford G. Venier; Edward W. Casserly; William R. Jones; Mario Marchetti; Mark J. Jansen
Archive | 2005
Mario Marchetti; William R. Jones; Stephen V. Pepper; Mark J. Jansen; Roamer E. Predmore
Archive | 2005
Kenneth W. Street; Randy L. VanderWal; Mario Marchetti; Aaron J. Tomasek