Spectrometric Analysis of Used Oils

Wright, B.R.

doi:10.4271/690776

Cited by 14 publications

(7 citation statements)

References 5 publications

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“…The stressful environment, into which lubricating oils are forced to operate, favors their degradations over time. This loss of performance is a result of a complex tribo-chemical (tribo-chemistry refers to chemical reactions taking place between lubricant (and/or environment) with surfaces in motion under lubrication conditions [4]) process (es) occurring within the engine [5]. Due to their active sites (functional groups) and conditions existing within the engine, additives are likely to degrade through a series of chemical reactions which invariably results in loss of their primary functions.…”

Section: Co-polymers Of Polyalkylmethacrylatesmentioning

confidence: 99%

Modeling and Forecasting of Depletion of Additives in Car Engine Oils Using Attenuated Total Reflectance Fast Transform Infrared Spectroscopy

2014

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On average, additives make up to 7% of a typical lubricant base. Commonly, they are blended with lube oils to enhance specific features thereby improving their qualities. Ultimately, additives participate in the performance of car engine oils. Using an analytical tool, attenuated total reflectance fast transform infrared spectroscopy, various grades of car engine oils, at different mileages, were analyzed. Sulfate oxidation and wear were found to trigger chemical processes which, in the long run, cause lubricant degradation while carbonyl oxidation was observed to occur only at a slow rate. Based upon data obtained from infrared spectra and using a curve fitting technique, mathematical equations predicting the theoretical rates of chemical change due to the aforementioned processes were examined. Additive depletions were found to obey exponential regression rather than polynomial. Moreover, breakpoint (breakpoint is used here to denote the initiation of deterioration of additives) and critical mileage (critical mileage defines the distance at which the lubricant is chemically unusable) of both samples were determined.

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Section: Co-polymers Of Polyalkylmethacrylatesmentioning

confidence: 99%

Modeling and Forecasting of Depletion of Additives in Car Engine Oils Using Attenuated Total Reflectance Fast Transform Infrared Spectroscopy

2014

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“…FTIR and EDS provided complimentary data on the chemical structure and elemental composition of PSMO deposits during their transition from nascent polymeric films to dark carbonaceous deposits. Specifically, EDS mapped the elemental composition of lubricant deposits across the PSMO test sequence, while FTIR‐attenuated total reflectance measured changes in hydroxyl, carbonyl and paraffinic functional groups …”

Section: Resultsmentioning

confidence: 95%

“…Alkyl or paraffinic (sp 3 ) C―H bonds absorb IR wavelengths of ~2922 cm −1 . Analysis of FTIR results revealed intensity changes in the alkyl and carbonyl stretching modes as a function of deposit age, as summarised in Figure . Monitoring these two regions for both the oil phase and the deposit film enables a direct comparison of the deposit chemistry formed during the PSMO relative to that of the degrading base oil.…”

Section: Resultsmentioning

confidence: 99%

“…Specifically, EDS mapped the elemental composition of lubricant deposits across the PSMO test sequence, while FTIR-attenuated total reflectance measured changes in hydroxyl, carbonyl and paraffinic functional groups. 25 Various absorption peaks evolved in intensity over the course of deposition and were attributed to characteristic functional groups formed during the oxidative degradation of base lubricants. 26 According to transition frequencies, their assignments to specific chemical groups are shown in Figure 5.…”

Section: Bmentioning

confidence: 99%

“…28 Analysis of FTIR results revealed intensity changes in the alkyl and carbonyl stretching modes as a function of deposit age, as summarised in Figure 6. 29 Monitoring these two regions for both the oil phase and the deposit film enables a direct comparison of the deposit chemistry formed during the PSMO relative to that of the degrading base oil. Specifically, the degree of carbonisation of PSMO-produced deposits was determined by monitoring the concentration of carbonyl and sp 3 hybridised carbon species across age.…”

Section: Bmentioning

confidence: 99%

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Deposit formation from lubricant degradation: a uniform layer deposition model

Kouame

Wal

Perez

2013

Lubrication Science

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Reported is a new model describing deposit formation and ageing along the so-called universal mass deposition curve. The penn state micro-oxidation (PSMO) apparatus produced model deposits at varied test durations in order to study the ageing mechanism of thin film deposits from mineral base oil. Along the 'universal' mass deposition curve, mass deposition rates were correlated to film chemistry. Formed by concerted oxidation-polymerisation reactions, chemical group and elemental content analyses were performed by Fourier transformed infrared spectroscopy-attenuated total reflectance and energy dispersive spectroscopy, respectively. The results showed that deposit formation initiates as a film -uniform in composition. After an induction period, the film growth accelerates then slows and eventually falls off, with a decrease in mass often observed. These stages reflect underlying physical and chemical changes as the deposit progresses from an initial polymeric, lacquer-type deposit, towards a final dark, carbonaceous deposit, along the universal mass deposition curve. Carbonyl, hydroxyl and sp 3 hybridised carbon were identified as the main functional groups found across all deposit types albeit at different levels. Correlative behaviour was observed between changes in functional group infrared intensities and O-atom and C-atom content. These trends are interpreted as reflecting concerted deoxygenation and dehydrogenation processes, throughout the deposit, over the course of ageing, thus providing a foundation for the uniform layer model.

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Investigation of subsequent deposit growth on pre‐existing lubricant deposits: a substitutional growth model

Kouame

Wal

Perez

2016

Lubrication Science

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The Penn State Micro-Oxidation (PSMO) test was used in an inverse manner to pre-cover metallic pan surfaces with polymeric, transitioning and carbonaceous films. These pre-coated pans were then used as the initial test specimen/surface upon which fresh lubricant samples were aged. The effects of predeposits of varied ages were gauged against the baseline of a virgin metallic surface to decouple the lubricant-deposit system towards resolving their effect upon further deposit growth. From such data, a uniform deposition model describing deposit formation and aging was developed. Chemical characterisation of PSMO deposits by Fourier transform infrared-attenuated total reflectance and energy-dispersive X-ray spectroscope analyses provide additional supporting evidence of changes in chemical bonding (alkyl C-H and carbonyl C=O bond stretching vibrations) and composition (C-and O-atom content) as the deposits undergo deoxygenation and dehydrogenation reactions. Across different aged oils and films, the substitution tests show a declining activity towards mass deposition with film age, interpreted as decline in reactivity.

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Spectrometric Analysis of Used Oils

Cited by 14 publications

References 5 publications

Modeling and Forecasting of Depletion of Additives in Car Engine Oils Using Attenuated Total Reflectance Fast Transform Infrared Spectroscopy

Modeling and Forecasting of Depletion of Additives in Car Engine Oils Using Attenuated Total Reflectance Fast Transform Infrared Spectroscopy

Deposit formation from lubricant degradation: a uniform layer deposition model

Investigation of subsequent deposit growth on pre‐existing lubricant deposits: a substitutional growth model

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