In-situ lubricating oil condition sensoring method based on two-channel and differential dielectric spectroscopy combined with supervised hierarchical clustering analysis

Gong, Yumei; Guan, Lei; Feng, X.L.; Wang, Liguang; Xin, Yu

doi:10.1016/j.chemolab.2016.09.004

Cited by 15 publications

(8 citation statements)

References 28 publications

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“…CA results at the molecular level were observed to be in good agreement with the changes observed to the physicochemical properties of the samples on the macro level. Gong et al observed that hierarchical CA results based on two-channel and differential dielectric spectroscopy (TD-DES) data were also in good agreement with those based on FT-IR data and proposed using the TD-DES technique to monitor the oil and conduct hierarchical CA [54]. Furthermore, the present study offered a platform for further researching the molecular mechanism of oil sample degradation performance.…”

Section: Ca Of the Oil Samplessupporting

confidence: 75%

“…CA is considered a principal task of data exploration, is a common technique for statistical analysis and chemometric approaches, and is widely used in molecular spectroscopy [51][52][53]. The results of CA were intended to elucidate the compound structure and compositional changes of SHALOs resulting from oxidative high-temperature degradation, allowing detection of the degradation stages of SHALOs and signaling of the need for an oil change when warranted by the oil conditions [54]. Furthermore, the SHALO clusters could be used to detect possible relationships between compound structure and compositional changes at the molecular level and, therefore, facilitate the discovery of physicochemical properties at the macro level.…”

Section: Ca Of the Oil Samplesmentioning

confidence: 99%

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Effect of Temperature on the Composition of a Synthetic Hydrocarbon Aviation Lubricating Oil

et al. 2020

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Synthetic hydrocarbon aviation lubricating oils (SHALOs) gradually degrade over time when subjected to high temperatures, resulting in their composition and properties varying over the operation lifetime. Therefore, understanding the SHALO degradation properties by elucidating the mechanism on a molecular level, as a function of high temperature, is of interest. A SHALO was subjected to thermal treatment (TT) at 180, 200, 230, 250, 270, or 300 °C for 2 h. The chemical compositions of six TT samples and one fresh oil were analyzed by fourier transform infrared F spectroscopy, advanced polymer chromatography, and gas chromatography/mass spectrometry. Furthermore, the physicochemical properties, such as kinematic viscosity, pour point, and acid number, of seven samples were determined. The oil samples were grouped by cluster analysis (CA) using a statistical method. The SHALO was identified to comprise 20 functional groups, including comb-like alkanes, long-chain diesters, amines, phenols, and other compounds. TT at <230 °C caused partial cracking of the SHALO base oils, with a concomitant change in the antioxidant content and type, and the polycondensation reactions were dominant. The observed antioxidant changes were not obvious from TT at >230 °C. A large number of small-molecule compounds were detected, including n-alkanes and olefins. TT at 250 °C was shown to be an important threshold for the kinematic viscosity, pour point, and acid number of the samples. Below 250 °C, the sample properties were relatively stable; but at elevated TT temperatures (>250 °C), the properties were observed to dramatically degrade. As the sample color was highly sensitive to temperature, the TT temperature induced rapid and significant color changes. The CA analysis results for the oil compounds at the molecular level were in good agreement with observed changes in the physicochemical properties at the macro level.

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Section: Ca Of the Oil Samplessupporting

confidence: 75%

Section: Ca Of the Oil Samplesmentioning

confidence: 99%

Effect of Temperature on the Composition of a Synthetic Hydrocarbon Aviation Lubricating Oil

et al. 2020

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“…However, dielectric constant also varies with AC frequency and the variation of dielectric constant of a lubricant with frequency can provide information about the concentration and rotational mobility of its polar and polarisable molecules. The study of how dielectric constant varies with frequency is termed dielectric spectroscopy (DES) [150], which can be used to characterise base oil composition as well as oil degradation [151][152][153]. In practice, EIS and DES are closely related.…”

Section: Non-aqueous Lubricantsmentioning

confidence: 99%

“…Their main practical limitation lies in difficulty of interpretation, since most lubricants are complex blends of polar additives that even without degradation provide a complicated impedance spectrum, which can be interpreted fully only if the formulation composition is already known. The addition of ill-defined degradation products such as oxidation products adds to this complexity so that some developers are applying machine-learning and other expert systems to interpret and correlate electrical measurements with lubricant composition [152,153]. While this difficulty of interpretation limits the value of EIS and related measurements as research tools to study lubricants per se, it does not detract from their value as empirical ways to monitor changes in lubricant electrical properties resulting from ageing during use and that provide a measure of lubricant condition.…”

Section: Non-aqueous Lubricantsmentioning

confidence: 99%

Triboelectrochemistry: Influence of Applied Electrical Potentials on Friction and Wear of Lubricated Contacts

Spikes

2020

Tribol Lett

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Research on the effects of applied electrical potential on friction and wear, a topic sometimes termed “Triboelectrochemistry”, has been reviewed. Historically, most such research has focussed on aqueous lubricants, whose relatively high electrical conductivities enable use of three-electrode electrochemical kinetic techniques, in which the electrode potential at a single electrode | fluid interface is controlled relative to a suitable reference electrode. This has led to identification of several different mechanisms by which applied electrode potentials can influence friction and wear. Of these, the most practically important are: (i) promotion of adsorption/desorption of polar additives on tribological surfaces by controlling the latters’ surface charges; (ii) stimulation or suppression of redox reactions involving either oxygen or lubricant additives at tribological surfaces. In recent years, there has been growing interest in the effects of applied electrical potentials on rubbing contacts lubricated by non-aqueous lubricants, such as ester- and hydrocarbon-based oils. Two different approaches have been used to study this. In one, a DC potential difference in the mV to V range is applied directly across a thin film, lubricated contact to form a pair of electrode | fluid interfaces. This has been found to promote some additive reactions and to influence friction and wear. However, little systematic exploration has been reported of the underlying processes and generally the electrode potentials at the interfaces have not been well defined. The second approach is to increase the conductivity of non-aqueous lubricants by adding secondary electrolytes and/or using micro/nanoscale electrodes, to enable the use of three-electrode electrochemical methods at single metal | fluid interfaces, with reference and counter electrodes. A recent development has been the introduction of ionic liquids as both base fluids and lubricant additives. These have relatively high electrical conductivities, allowing control of applied electrode potentials of individual metal | fluid interfaces, again with reference and counter electrodes. The broadening use of “green”, aqueous-based lubricants also enlarges the possible future scope of applied electrode potentials in tribology. From research to date, there would appear to be considerable opportunities for using applied electrical potentials both to promote desirable and to supress unwanted lubricant interactions with rubbing surfaces, thereby improving the tribological performance of lubricated machine components. Graphical Abstract

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“…Incorporating this pattern recognition, image analysis and information(attributes) retrieval generated, while picking effects and interactions which require to be addressed, offer maintenance decision making support. Cluster analysis has been used in several LCM related studies in the recent past such as [163][164] [165]. CA experiences some limitations that influence the subsequent results such as sampling errors and biasness towards setting the optimal number of clusters due to its heuristic nature as well.…”

Section: Logistics Regression (Lr)mentioning

confidence: 99%

A review on lubricant condition monitoring information analysis for maintenance decision support

Wakiru

Pintelon

Muchiri

et al. 2019

Mechanical Systems and Signal Processing

137

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In-situ lubricating oil condition sensoring method based on two-channel and differential dielectric spectroscopy combined with supervised hierarchical clustering analysis

Cited by 15 publications

References 28 publications

Effect of Temperature on the Composition of a Synthetic Hydrocarbon Aviation Lubricating Oil

Effect of Temperature on the Composition of a Synthetic Hydrocarbon Aviation Lubricating Oil

Triboelectrochemistry: Influence of Applied Electrical Potentials on Friction and Wear of Lubricated Contacts

A review on lubricant condition monitoring information analysis for maintenance decision support

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