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2 Applied Mechanics and Engineering

2 1999

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Tribological properties of PTFE bonded lamella solid lubricants

Kawamura M., Mogami A., Takeichi Y., Uemura M.

Applied Mechanics and Engineering

1999

Vol. 4, no spec.

231-236

Polytetrafluoroethylene (PTFE) is generally used in conjunction with fiber filler and common lamella solid lubricants to enhance tribological performance. In order to clarify the interaction between PTFE and lamella solid lubricants, we conducted friction tests under vacuum and normal air conditions, and the results were combined with a surface analysis to estimate the physical and chemical changes that occurred on the sliding surface. According to our study, the coefficient of friction of the tested sheet material increased as speed increased under a low load, while it decreased as speed increased under a high load. We assume that the friction_al properties of PTFE were predominant under a low load: those of lamella solid lubricant were predominant under a high load. The sliding surface was subjected to a surface analysis, the density of PTFE at the top-most portion of the sliding surfaces of both ring and sheet specimens were higher than those of the under layer.

The thickness effects of copper interlayer on frictional properties of lead-tin thin film

Takeichi Y., Ariga N., Li C. S., Uemura M., Dzimko M.

Applied Mechanics and Engineering

1999

Vol. 4, no spec.

189-194

The effects of the thickness of copper interlayer on frictional properties of lead-tin thin films were investigated. Thin film and interlayer were formed by vacuum deposition. The thickness of lead-tin film was about 0.06, 0.09, 0.19 and 0.43 žm. Ball-on-disk type friction test was carried out in vacuum. The load was increased and decreased for the range of about 0.1 to 0.6 N in the "variable load friction test". The thin film with thicker interlayer (~ 30 nm) showed higher friction coefficient as compared to the results for the thin film with thinner interlayer (~ 3 nm). However, abrupt increase in friction coefficient by break down of thin film was not observed for the thin film with thicker interlayer. Moreover, longer endurance life was attained for the thin film with thicker interlayer in the "endurance life friction test". Adhesion of copper to glassy material is greater than that of lead or tin. Also copper would bind tightly with tin by migration. Therefore durability of thin film with thicker copper interlayer would be prolonged although friction coefficients were increased because of the higher shearing strength for copper as compared with that for lead or tin.