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Performan
适用范围
Zinc di--alkyl dithio--phosphate (ZnDTP) compounds are widely used in engine and transmission oils both as
anti--oxidants and as anti--wear additives. However, recent work has shown that many anti--wear additives
appear to have a detrimental effect on the resistance of gears and other contacting components to various
types of rolling contact fatigue, including micropitting. In the present paper we examined the effect of the
presence of a secondary C6 ZnDTP in a low viscosity synthetic base oil on the resistance to micropitting and
wear of carburised steel rollers, using a triple--contact disk tester.
It was found that the additive caused severe micropitting and associated wear, whereas the pure base oil did
not give rise to any micropitting. It was further found that the additive was not detrimental unless it was present
during the first 100 000 cycles of the test when it was found to exert a strong effect on the development of
roughness on the counter--rollers. It is concluded that the additive is detrimental to micropitting resistance
because it retards wear--in of the contact surfaces, favouring the development of damaging fatigue cracks.
This contrasts with some earlier speculation that suggested a direct chemical effect could be responsible.