Lube-Tech PUBLISHED BY LUBE: THE EUROPEAN LUBRICANTS INDUSTRY MAGAZINE
PAO 40 based bentonite clay greases, treated with same additive systems, show high rates of evaporation and thermal degradation (Figure 7) right from the beginning of test. Thermo-oxidative degradation quickly generates high amounts of hard deposit, leaving approximately 60% residue.
The curves also confirm the evaporation/decomposition profile is related to the chemistry of base fluid rather than additive system.
No.95 page 6
Use of an oligomer-based additive for stabilizing a lubricating composition for a conveyor chain, patent US 8492321 B2, Gérard Goujon, Florence Severac, Marc Borel-Garin, NYCO.
(2) Prediction of high temperature grease life using a decomposition kinetic model, In-Sik Rhee, Presented at the NLGI 76th Annual Meeting, Tucson, Arizona, USA, June 13-16, 2009.
Figure 7. PAO 40 and ester based greases, thermogravimetric analysis, 230°C Conclusion
By selecting a specifically designed thermally stable ester, treating it with a high performance anti-oxidant system, and thickening it with a carefully selected bentonite clay, it is possible to produce a mechanically stable NLGI 1 grease. This grease shows remarkably low evaporation rates and unchanged consistency up to its induction time, measured at 2100 min at 230°C and 400 min at 250°C on TGA equipment under oxygen flow. It leaves very little residue after decomposition. These results suggest such a grease could be used at operating temperatures of 180°C to 230°C. We can confirm it should perform well where PAO based greases stop being suitable, and should be able to replace silicone/fluorinated fluid based products over a wider than initially expected temperature range.
Acknowledgements: I would like to thank the following people for their contribution to this work: Marc Emo, who generated and collected all technical data Gérard Goujon, for his technical guidance.
For further information please contact info@nycofr.
LINK
www.nyco.fr
(1) Use of an oligomer-based additive for stabilizing a lubricating composition for a conveyor chain, patent EP 2350241 A1, Gérard Goujon, Florence Severac, Marc Borel-Garin, NYCO.
36 LUBE MAGAZINE NO.123 OCTOBER 2014
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