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This paper examines the effect of dispersant and anti-wear additives on fretting wear in lubricated bearing steel contacts. Reciprocating sliding ball-on-flat fretting tests with a stroke length of 50 μm have been carried out on steel-to-steel contacts in both dry and lubricated conditions. Wear and friction coefficient have been measured, and surface characterisation has been carried out using optical techniques to investigate fretting wear. The presence of base oil reduces fretting wear markedly compared to dry conditions, but fretting damage is still observed at low reciprocation frequencies. As frequency is increased, there is a transition from oxidative to adhesive/scuffing damage. The anti-wear additive ZDDP is effective in forming a tribofilm on the surfaces and reducing visible oxidation and wear. A succinimide dispersant also reduces the accumulation of solid debris but does not alleviate wear damage. The combination of both ZDDP anti-wear additive and dispersant in base oil appears to provide significant protection against fretting wear. [ABSTRACT FROM AUTHOR]

Discusses how the breeding performance of higher predators has often been used to monitor fluctuations in the abundance of important prey stocks in marine ecosystems.

Discusses how variability in the Southern Ocean is frequently reflected in changes in the abundance of Antarctic krill Euphausia superba and subsequent effects on dependent predators. Observation that the nature and consequences of changes in krill population dynamics that accompany fluctuations in its abundance are essentially unknown.