On Monitoring Physical and Chemical Degradation and Life Estimation Models for Lubricating Greases

Rezasoltani, Asghar; Khonsari, M. M.

doi:10.3390/lubricants4030034

Cited by 32 publications

(27 citation statements)

References 42 publications

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“…Two degradation mechanisms of greases are described in the literature: physical degradation and the chemical one [5][6][7][8]. Physical degradation includes mechanical degradation of the thickener structure as a result of shear stress, separation of base oil and thickener, evaporation of base oil, and grease contamination by pollutants and debris.…”

Section: Degradation Systems Of Greasesmentioning

confidence: 99%

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The Effect of Addition of Nanoparticles, Especially ZrO2-Based, on Tribological Behavior of Lubricants

Rylski

Siczek

2020

Lubricants

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The aim of the paper was to discuss different effects, such as, among others, agglomeration of selected nanoparticles, particularly those from zirconia, on the tribological behavior of lubricants. The explanation of the difference between the concepts of ‘aggregation’ and ‘agglomeration’ for ZrO2 nanoparticles is included. The factors that influence such an agglomeration are considered. Classification and thickeners of grease, the role of additives therein, and characteristics of the lithium grease with and without ZrO2 additive are discussed in the paper. The role of nanoparticles, including those from ZrO2 utilized as additives to lubricants, particularly to the lithium grease, is also discussed. The methods of preparation of ZrO2 nanoparticles are described in the paper. The agglomeration of ZrO2 nanoparticles and methods to prevent it and the lubrication mechanism of the lithium nanogrease and its tribological evaluation are also discussed. Sample preparation and a ball-on disc tester for investigating of spinning friction are described. The effect of ZrO2 nanoparticles agglomeration on the frictional properties of the lithium grease is shown. The addition of 1 wt.% ZrO2 nanoparticles to pure lithium grease can decrease the friction coefficient to 50%. On the other hand, the agglomeration of ZrO2 nanoparticles in the lithium grease can increase twice the friction coefficient relative to that for the pure grease.

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Section: Degradation Systems Of Greasesmentioning

confidence: 99%

“…Rezasoltani and Khonsari [8] described other mechanisms of grease degradation, such as grease flow resulting in its starvation. However, this should be considered as a malfunction of the lubrication system rather than the mechanism of degradation of the grease itself.…”

Section: Degradation Systems Of Greasesmentioning

confidence: 99%

The Effect of Addition of Nanoparticles, Especially ZrO2-Based, on Tribological Behavior of Lubricants

Rylski

Siczek

2020

Lubricants

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“…At present, the most widely used and effective oil monitoring technologies are lubricant's physical and chemical index analysis [37,38] and wear particle analysis [39]. The physical and chemical index analysis of lubricants is to monitor the lubrication status of the equipment by monitoring the degree of changes in the physicochemical properties of the oil due to the loss of additives and the decay of the base oil.…”

Section: Main Monitoring Methods For the Suspended Particles In Lubrimentioning

confidence: 99%

Research Progress on Monitoring and Separating Suspension Particles for Lubricating Oil

et al. 2018

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Lubricant failure or irrational lubrication is the root cause of industrial equipment failure. By monitoring the distribution of the suspended particles in lubricants, it is possible to discover hidden lubrication problems. After taking the lubricating oil samples of industrial equipment, the oil monitoring technology is used to analyze the particle size distribution and the type and content of the abrasive particles by electrical, magnetic, and optical monitoring techniques. It is necessary to separate the suspended particles in oils with impurities by some method to eliminate potential safety hazards and ensure the reuse efficiency of the lubricant. In this paper, the principles, advantages, and disadvantages of several important oil monitoring methods are described, and new developments in various methods are analyzed. Several typical methods for separation of the suspended particles in purified oils were introduced. The advantages and disadvantages of each process were summarized. The development direction of lubricant monitoring technology was pointed out, and guidance was provided for the separation and online monitoring of the suspended particles in lubricants. Finally, compared with similar review papers, this paper specifically figured out that ultrasonic separation method has the advantages of real time, high efficiency, and no pollution and has important application value for micron-scale particle separation of large precision machines.

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“…Grease degradation can be broken down into two regimes: physical degradation and chemical degradation [5][6][7][8]. Physical degradation includes mechanical degradation of the thickener structure due to shearing, separation of the base oil and thickener, evaporation of the base oil, and contamination of the grease by foreign particles.…”

Section: Introductionmentioning

confidence: 99%

The Use of Entropy in Modeling the Mechanical Degradation of Grease

Gurt

Khonsari

2019

Lubricants

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Recent theoretical developments linking degradation to the thermodynamic concept of entropy have allowed a new approach to modeling all types of degradation. The theory has been successfully applied to wear, fatigue, and numerous other forms of degradation and experimentation has confirmed its applicability to modeling the mechanical degradation of lubricating grease. This paper overviews the mechanical degradation of grease, discusses past and present modeling techniques, shows how new techniques can be used to predict grease life, and provides suggestions for future research.

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On Monitoring Physical and Chemical Degradation and Life Estimation Models for Lubricating Greases

Cited by 32 publications

References 42 publications

The Effect of Addition of Nanoparticles, Especially ZrO2-Based, on Tribological Behavior of Lubricants

The Effect of Addition of Nanoparticles, Especially ZrO2-Based, on Tribological Behavior of Lubricants

Research Progress on Monitoring and Separating Suspension Particles for Lubricating Oil

The Use of Entropy in Modeling the Mechanical Degradation of Grease

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