Formulation, rheology and thermal aging of polymer greases—Part II: Influence of the co-thickener content

Gonçalves, David; Marques, R. Pitanga; Graça, Beatriz; Campos, A.; Seabra, Jorge; Leckner, Johan; Westbroek, Renéx

doi:10.1016/j.triboint.2015.01.012

Cited by 24 publications

(9 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Hurley et al studied the thermal aging problem of grease at 120℃. The results proved that the soap fiber will be destroyed under long exposure in high temperature and the properties of grease will be affected [28][29][30] .…”

Section: Introductionmentioning

confidence: 94%

Effect of temperature on rheological properties of lithium-based magnetorheological grease

Wang

Zhang

et al. 2019

Smart Mater. Struct.

View full text Add to dashboard Cite

This paper investigates the impact of temperature on the rheological properties of magnetorheological (MR) grease containing carbonyl iron suspended in lithium-based grease within the temperature range from 10℃ to 70℃under influence of temperature, i.e. from 10℃ to 70℃. Lithium-based MR grease with 70% weight fraction of carbonyl iron has beenis firstly prepared by mechanical mixing. The apparent viscosity and shear stress as a function of shear rate under different temperatures and magnetic field strengths are measured and discussed. It is found that the influence of temperature on apparent viscosity is reducingreduces with the increase of magnetic field strength. In addition, in the presence of magnetic field, maximum yield stress gets demonstrates an increase as temperature increases from 50℃ to 60℃. The dynamic properties of MR grease are obtained under oscillatory shear test. The influences of strain amplitude, driving frequency and magnetic field on the dynamic properties of MR grease at different temperature are discussed. The results demonstrate that the enhancement of temperature leads to the increase of storage modulus and the reduction of the loss factor. Microstructural variation of grease matrix at different temperature is proposed as an explanation of the rheological changes of MR grease.

show abstract

Section: Introductionmentioning

confidence: 94%

Effect of temperature on rheological properties of lithium-based magnetorheological grease

Wang

Zhang

et al. 2019

Smart Mater. Struct.

View full text Add to dashboard Cite

show abstract

“…This work focused only on the very recent polymer-thickened greases [18,27,28,[32][33][34] and the very common-and already proven-good performance, multi-purpose, lithium-thickened greases [4,35,36]. The experimental tests shown here should be extended to different thickener-base oil combinations to determine whether the observed phenomena could be generally applied to different formulations.…”

Section: Discussionmentioning

confidence: 99%

“…This behaviour is attributed to the thickener material crossing the contact, and the scatter can be considerably high in this region. Upon reaching a certain minimum value, the film thickness starts to increase at a slope of U 0.67 , typical of oil lubrication [25][26][27][28][29]. Not all greases show this behaviour under the same temperature or speed range.…”

Section: Central Film Thickness Measured With Varying Entrainment Speedmentioning

confidence: 99%

An Experimental Study on Starved Grease Lubricated Contacts

2018

Self Cite

View full text Add to dashboard Cite

The film thickness of a ball-on-disc contact lubricated with four greases of different formulations was measured under different operating conditions until starvation. Two polymer-thickened greases and two lithium-thickened greases, formulated with base oils of different nature and/or viscosity, were tested. The central film thickness was measured under constant operating conditions (load, temperature, slide-to-roll ratio) varying only the entrainment speed. In a separate test, the film thickness was measured over time with all operating conditions set to constant. Pictures of the film thickness profile across the contact area were also registered. The results were compared with the fully flooded results. The coefficient of friction (COF) was measured in a ball-on-disc contact under equal operating conditions and the results were correlated with the film thickness findings. The different grease formulations and the influence of the operating conditions on the film thickness and COF were discussed. The polymer thickened the greases, promoting lower COF and higher film thickness, especially when there is thickener material crossing the contact which happens quite often for these greases.

show abstract

“…W kolejnych publikacjach (Gonçalves et al, 2015a(Gonçalves et al, , 2015b(Gonçalves et al, , 2016 opisano zmiany zachodzące podczas starzenia smarów polimerowych i litowych, odwzorowując warunki pracy smarów w łożyskach tocznych. Próbki smarów w postaci cienkiej warstwy o grubości 1 mm nałożono na tarcze stalowe i umieszczono na 5 dni w piecu o temperaturze 120°C.…”

Section: Modyfikacja Stabilności Termooksydacyjnej Smarówunclassified

Stabilność termooksydacyjna smarów plastycznych

Skibińska¹,

Badawczy²

2021

View full text Add to dashboard Cite

This review article deals with a particular property of lubricating greases – resistance to oxidation. This property, also referred to as oxidative or thermal oxidation stability, has a decisive influence on the quality and duration of lubricating greases service life in friction nodes, bearings and lubrication systems. Lubricating greases are colloidal systems in which the thickener creates an elastic three-dimensional network, maintaining the liquid phase. The structure of lubricating greases, division of greases into types, depending on the thickener used, is presented. The basic additives in lubricating greases are described, and the group of used antioxidant additives is discussed in detail. Under operating conditions, the grease is subject to factors that cause its destruction – shear stress, pressure, loads, changing operating conditions, especially temperature changes. The types of lubricating greases degradation are presented, as well as methods and techniques of aging processes evaluation. During operation, the grease fulfilling its basic functions in the lubrication system is primarily exposed to high temperatures. The predominant aging process which directly affects the service life of the grease is oxidation. The oxidation process is discussed, with the specification of its four stages: initiation, propagation, chain branching and termination. One of the methods of preventing the oxidation process is the selection of appropriate improvers. Thermal oxidation stability of greases can be modified by introducing appropriate antioxidants, the selection of which depends on the type of grease thickener and the operating temperature of the grease. The published literature review from over the last ten years shows how diverse are the ways of modifying thermal oxidation stability of greases and the methods of assessing this property.

show abstract

Formulation, rheology and thermal aging of polymer greases—Part II: Influence of the co-thickener content

Cited by 24 publications

References 16 publications

Effect of temperature on rheological properties of lithium-based magnetorheological grease

Effect of temperature on rheological properties of lithium-based magnetorheological grease

An Experimental Study on Starved Grease Lubricated Contacts

Stabilność termooksydacyjna smarów plastycznych

Contact Info

Product

Resources

About