This research was aimed to the elaboration of a new technology for heavy-loaded machine elements, lubricated with ecological oils without or with very limited amount of usually harmful AW/EP additives used in gear oils. The main objective of the study was the investigation of the effect of DLC coatings on scuffing resistance of coated gears. Three kinds of DLC coatings were tested: a-C:H:W, a-C:Cr and a-C:H. The gear tests were preformed using FZG A/8.3/90 method, employing the T-12U gear testing rig. The gears were lubricated with eco-oil. For the a-C:H:W coated gears, lubricated with ecological oil, the oil temperature was lower by 20 °C, and the friction was lowered by 20% compared with uncoated steel gears, lubricated with high-performance GL-5 gear oil. Thus it has been shown here that under extreme pressure conditions low friction coatings can take over the functions of AW/EP additives and make it possible to use ecological oils for lubrication.
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20. DIN 51 354. Teil 2. FZG - Zahnrad - Verspannungs - Prüfmaschine. Prüfverfahren A/8,3/90 für Schmieröle.
21. IP 334/86. Load-carrying capacity tests for oils (FZG gear machine).
