The Tribofilm Formation of ZDDP Under Reciprocating Pure Sliding Conditions

Shimizu, Yasunori; Spikes, H. A.

doi:10.1007/s11249-016-0776-6

Cited by 39 publications

(27 citation statements)

References 22 publications

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“…However it can be seen that ZDDP film formation rate is much slower with 0.1 wt% N dispersant concentration. These results also confirm the rapid formation of sulphide in the film in pure sliding, reciprocating contact, as noted by Shimizu et al [28].…”

Section: Influence Of Dispersant On Zddp Reaction Ratesupporting

confidence: 91%

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Influence of Dispersant and ZDDP on Soot Wear

et al. 2018

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Diesel engines and gasoline direct injection (GDI) engines both produce soot due to incomplete combustion of the fuel and some enters the lubricant where it accumulates between drain intervals, promoting wear of rubbing engine components. Currently the most favoured mechanism for this wear is that the anti-wear additives present in engine oils, primarily zinc dialkyldithiophosphates (ZDDPs), react very rapidly with rubbing surfaces to form relatively soft reaction products. These are easily abraded by soot, resulting in a corrosive-abrasive wear mechanism. This study has explored the impact of engine oil dispersant additives on this type of wear using combinations of dispersant, ZDDP and carbon black, a soot surrogate. It has been found that both the concentration and type of dispersant are critical in influencing wear. With most dispersants studied, wear becomes very high over an intermediate dispersant concentration range of ca 0.1-0.4 wt% N, with both lower and higher dispersant levels showing much less wear. However a few dispersants appear able to suppress high wear by ZDDP and carbon black over the whole concentration range. A series of experiments have been carried out to determine the origin of this behaviour and it is believed that high levels of dispersant, and, for a few dispersants, all concentration levels, protect the iron sulphide tribofilm initially formed by ZDDP from abrasion by carbon black.

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Section: Influence Of Dispersant On Zddp Reaction Ratesupporting

confidence: 91%

“…The MTM was also used in reciprocating, pure sliding mode to study the influence of dispersants on initial ZDDP film formation [28]. A stationary MTM ball is loaded at 20 N against an MTM disc that rotates back and forth at 20 Hz over a stroke length of 4 mm.…”

Section: Reciprocating Mtm To Study Initial Zddp Film Formationmentioning

confidence: 99%

Influence of Dispersant and ZDDP on Soot Wear

et al. 2018

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“…The mini traction machine-space layer imaging (MTM-SLIM), PCS Instrument is a well-known and useful method to monitor ZDDP tribofilm growth in situ, and its use to study the kinetics of ZDDP tribofilm growth has been reported widely [11][12][13][14][15][16][17][18][19][20][21][22]. In this paper, MTM-SLIM has been used to monitor ZDDP tribofilm formation and wear on the ferrous counter-surface rubbed against Al-Si alloys.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Aluminium–Silicon Alloy on ZDDP Tribofilm Formation on the Counter-Surface

Shimizu

Spikes

2017

Tribol Lett

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In order to reduce vehicle weight and thus improve fuel economy, aluminium (Al) alloys have been increasingly adopted as contact surfaces such as piston skirts and cylinder liners in current engines. In general, hypereutectic Al-Si alloys are used, in which hard silicon grains are embedded in a softer Al-Si single phase matrix. It is reported that after rubbing, the matrix is removed to leave silicon grains protruding from the surface. However, the response of the counter-surface by these silicon grains is rarely investigated. In this study, mini traction machinespace layer imaging (MTM-SLIM) has been used to monitor tribofilm formation in situ and investigate the evolution of both surfaces in the contact of a steel ball on an Al-Si disc lubricated by ZDDP solution. In low-load conditions, the top layer of aluminium on the Al-Si disc is removed physically to leave silicon grains protruding from the surface, while ZDDP tribofilm pads are formed mainly on the grains. On the counter-surface (steel ball), ZDDP tribofilms are formed and build up with no wear scars. In high-load conditions, deep gaps are observed to form initially round the silicon grains on the disc. During rubbing, these become shallower, while the silicon grains start to protrude. On the steel ball, ZDDP tribofilm is generated initially over the whole rubbing track, but then the tribofilm in the middle of the track is almost completely removed by rubbing against the protruding silicon grains. Wear of the underlying steel surface then ensues.

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“…In fact, Shimizu and Spikes found that initial tribofilm formation on Fe alloys is S rich, and subsequently becomes more Zn and P rich. [31] However, it is reasonable to expect that S will have stronger bonding interactions with Fe than the Si-O terminated substrate utilized here. This could explain why our films initially grow more Zn and P rich.…”

Section: Resultsmentioning

confidence: 90%

Local chemo-mechanical insights into the efficacy of ZDDP additives from in situ single asperity growth and mechanical testing

Liu

Tang

Hao

et al. 2017

Tribology International

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This work combines nanoscale tribological wear methods, used to prepare zinc dialkyldithiophosphate (ZDDP) tribofilms under conditions of controlled loading, with site specific nanopillar compression testing to derive a relationship between the ZDDP growth conditions and resultant mechanical properties. The key finding is that ZDDP films grown at higher loads exhibit lower yield strengths, which correlate with differences in tribofilm chemistry. We hypothesize that the load sensitivity tribofilm properties may underlie the efficacy of ZDDP in suppressing wear by functioning as a hard coating at low loads while exhibiting enhanced lubricity at high loads.

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The Tribofilm Formation of ZDDP Under Reciprocating Pure Sliding Conditions

Cited by 39 publications

References 22 publications

Influence of Dispersant and ZDDP on Soot Wear

Influence of Dispersant and ZDDP on Soot Wear

The Influence of Aluminium–Silicon Alloy on ZDDP Tribofilm Formation on the Counter-Surface

Local chemo-mechanical insights into the efficacy of ZDDP additives from in situ single asperity growth and mechanical testing

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