Soot characterisation and diesel engine wear

Jao, Tze‐Chi; Li, S.; Yatsunami, Kenji; Chen, Shiahn J.; Csontos, A.; Howe, James M.

doi:10.1002/ls.3010160203

Cited by 40 publications

(23 citation statements)

References 11 publications

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“…Carragher has suggested that carbon black is very soft, with hardness of ca 1 on the Mohs scale [35]. However Jao et al [26] and Yamamoto and co-workers [36] suggest much higher hardness values for soot of between 8 and 10 GPa using quite different measurement methods. Based on this Jao proposed that soot promotes wear by abrading steel surfaces.…”

Section: Discussionmentioning

confidence: 99%

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Antagonistic Interaction of Antiwear Additives and Carbon Black

2009

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SUMMARYIt is well known that the presence of soot in engine oils can lead to an increase in wear of engine parts. This is a growing problem as soot levels in diesel engine oils are rising due to a combination of extended drain intervals and the various methods employed to reduce NOx formation such as retarded ignition and exhaust gas recirculation.Several different mechanisms have been proposed by which soot might lead to an increase in wear in mixed lubrication conditions, of which the most widely favoured is abrasion by soot, either of the rubbing metallic parts in engines or of the antiwear additive films formed on rubbing metal surfaces.In this study it is shown that the combination of mixed alkyl ZDDP and carbon black (used as soot surrogate) is strongly antagonistic in terms of wear. In a lubricant containing carbon black, the presence of ZDDP leads to considerably more wear than if ZDDP is left out. A similar, though less severe antagonism is also seen with primary ZDDP and other antiwear and EP additives. By varying the lubricant film thickness it is shown that the effect of carbon black in ZDDP-containing oils is to promote wear up to quite thick hydrodynamic film conditions, approaching the secondary carbon black particle size.It is proposed that the antagonistic wear effect results from a corrosion-abrasive mechanism in which the reaction film formed by antiwear additive and rubbing metal surface is very rapidly and continually abraded by carbon black. At most carbon black concentrations, wear rate then becomes controlled by the rate of initial antiwear additive film formation, which for secondary ZDDP is very rapid, rather than by the kinetics of the abrasive process.From this understanding, strategies for reducing the impact of engine soot on wear can be deduced.

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Section: Discussionmentioning

confidence: 99%

“…However Bardasz et al concluded that soot aggregates were responsible for abrasion [13]. Jao [26] showed that soot particles were sufficiently hard to abrade metal diesel engine parts. The wear scars caused by soot particles were found to contain grooves equivalent to the carbon primary particle size.…”

Section: Introductionmentioning

confidence: 99%

Antagonistic Interaction of Antiwear Additives and Carbon Black

2009

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“…Carraher [19] reported that CB is very soft with a hardness of ca 1 on the Mohs scale. However, Jao [20], using a different measurement method, suggested a higher value between 8 and 10 GPa.…”

Section: Methodsmentioning

confidence: 96%

Corrosive–Abrasive Wear Induced by Soot in Boundary Lubrication Regime

et al. 2016

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Soot is known to induce high wear in engine components. The mechanism by which soot induces wear is not well understood. Although several mechanisms have been suggested, there is still no consensus. This study aims to investigate the most likely mechanism responsible for soot-induced wear in the boundary lubrication regime. Results from this study have shown that previously suggested mechanisms such as abrasion and additive adsorption do not fully explain the high wear observed when soot is present. Based on the results obtained from tests conducted at varying temperature and soot levels, it has been proven that the corrosive-abrasive mechanism was responsible for high wear that occurred in boundary lubrication conditions.

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“…Mogul L is a low-structure CB; it was chosen because it had an oxidised surface to facilitate dispersion and a mean particle diameter size of 24 nm, which is comparable to primary particle sizes observed for diesel soots. 7,20,21 The CB was ultrasonically dispersed in the oils using the Vibracell (Sonics & Materials, Inc., Newtown, CT, USA) at 20 kHz and 33 W for 5 min. The dispersions appeared stable over weeks.…”

Section: Oil Samplesmentioning

confidence: 99%

Soot–additive interactions in engine oils

O׳Neill

Simko

et al. 2009

Lubrication Science

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Soot is known to cause engine wear. In this work, we focus on how engine oil formulation affects sootrelated wear, and how the lubricant-derived anti-wear fi lm changes when soot is present. Friction and wear experiments of fully and partially formulated diesel engine oils (containing basestock, dispersants and viscosity modifi ers) are conducted with a ball-on-disk rig in the presence of carbon black (CB) as a soot surrogate. The friction coeffi cient was largely unaffected by CB dispersed in the oils, but electrically insulating fi lm formation, an indication of the formation of anti-wear fi lms, was decreased. Wear on the disk was found to either remain the same or decrease when CB was present, depending on the oil formulation. An examination of the lubricant-derived fi lms using Raman and Auger electron spectroscopies found that the presence of more abundant amorphous carbon and lesser amounts of anti-wear fi lm components on the surface was associated with higher wear.

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Soot characterisation and diesel engine wear

Cited by 40 publications

References 11 publications

Antagonistic Interaction of Antiwear Additives and Carbon Black

Antagonistic Interaction of Antiwear Additives and Carbon Black

Corrosive–Abrasive Wear Induced by Soot in Boundary Lubrication Regime

Soot–additive interactions in engine oils

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