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Factorial study of diesel engine oil contamination effects on steel and ceramic sliding contacts

Factorial study of diesel engine oil contamination effects on steel and ceramic sliding contacts
Factorial study of diesel engine oil contamination effects on steel and ceramic sliding contacts
The present work investigates the effects of diesel contaminants and their interaction on tribological properties for bearing steel (En31) and ceramic (Si3N4) sliding contacts using a factorial study. The contaminants are soot, sulphuric acid, moisture and oxidation, and each contaminant has three different level of concentration (low, medium and high) in the test matrix. The factorial test matrix consisted of 20 tests, constructed from a quarter fractional factorial test matrix with four points at the medium values for the contaminants. Results from this matrix required six further tests to elucidate aliased pairs of interactions using Bayesian model selection. A pin-on-disc tribometer was used to carry out all the experiments. All tests were carried out under ambient conditions at 5 m/s sliding speed and contact stress of 1.5–2.05 GPa to simulate a valve-train in a diesel engine with fully formulated heavy-duty diesel engine oil used as lubricant. Four different tribological properties were studied. The factorial study showed that charge was influenced by tribocouple material; the silicon nitride discs produced higher charge than steel discs. However, it was opposite for friction; the silicon nitride disc gave lower friction and the pins showed higher friction than their steel counterparts. For wear scar and temperature, soot contaminant was found to be important. The two important interactions were found for the charge response, with the interaction between sulphuric acid and pin material being more important than sulphuric acid–oxidation interaction. Similarly to charge, an interaction between sulphuric acid and pin material interaction was found for friction.
Bayesian model selection,, ceramic, contamination, factorial design, sliding wear, soot
1350-6501
1-15
Penchaliah, Ramkumar
6dd58dd4-6cb9-4624-8463-888b7708cf4d
Harvey, Terence
3b94322b-18da-4de8-b1af-56d202677e04
Wood, Robert
d9523d31-41a8-459a-8831-70e29ffe8a73
Woods, David
ae21f7e2-29d9-4f55-98a2-639c5e44c79c
Lewis, Susan
a69a3245-8c19-41c6-bf46-0b3b02d83cb8
Rose, Andrew
1688832b-7fec-489a-a330-8252ec3deac5
Penchaliah, Ramkumar
6dd58dd4-6cb9-4624-8463-888b7708cf4d
Harvey, Terence
3b94322b-18da-4de8-b1af-56d202677e04
Wood, Robert
d9523d31-41a8-459a-8831-70e29ffe8a73
Woods, David
ae21f7e2-29d9-4f55-98a2-639c5e44c79c
Lewis, Susan
a69a3245-8c19-41c6-bf46-0b3b02d83cb8
Rose, Andrew
1688832b-7fec-489a-a330-8252ec3deac5

Penchaliah, Ramkumar, Harvey, Terence, Wood, Robert, Woods, David, Lewis, Susan and Rose, Andrew (2018) Factorial study of diesel engine oil contamination effects on steel and ceramic sliding contacts. Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, 1-15. (doi:10.1177/1350650118794730).

Record type: Article

Abstract

The present work investigates the effects of diesel contaminants and their interaction on tribological properties for bearing steel (En31) and ceramic (Si3N4) sliding contacts using a factorial study. The contaminants are soot, sulphuric acid, moisture and oxidation, and each contaminant has three different level of concentration (low, medium and high) in the test matrix. The factorial test matrix consisted of 20 tests, constructed from a quarter fractional factorial test matrix with four points at the medium values for the contaminants. Results from this matrix required six further tests to elucidate aliased pairs of interactions using Bayesian model selection. A pin-on-disc tribometer was used to carry out all the experiments. All tests were carried out under ambient conditions at 5 m/s sliding speed and contact stress of 1.5–2.05 GPa to simulate a valve-train in a diesel engine with fully formulated heavy-duty diesel engine oil used as lubricant. Four different tribological properties were studied. The factorial study showed that charge was influenced by tribocouple material; the silicon nitride discs produced higher charge than steel discs. However, it was opposite for friction; the silicon nitride disc gave lower friction and the pins showed higher friction than their steel counterparts. For wear scar and temperature, soot contaminant was found to be important. The two important interactions were found for the charge response, with the interaction between sulphuric acid and pin material being more important than sulphuric acid–oxidation interaction. Similarly to charge, an interaction between sulphuric acid and pin material interaction was found for friction.

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Factorial study of diesel engine oil contamination effects on steel and ceramic sliding contacts - Accepted Manuscript
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More information

Accepted/In Press date: 24 July 2018
e-pub ahead of print date: 23 August 2018
Keywords: Bayesian model selection,, ceramic, contamination, factorial design, sliding wear, soot

Identifiers

Local EPrints ID: 423839
URI: http://eprints.soton.ac.uk/id/eprint/423839
ISSN: 1350-6501
PURE UUID: 244f826a-e6a6-4750-8635-c9254660564a
ORCID for Robert Wood: ORCID iD orcid.org/0000-0003-0681-9239
ORCID for David Woods: ORCID iD orcid.org/0000-0001-7648-429X

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Date deposited: 02 Oct 2018 16:30
Last modified: 20 Jul 2019 01:19

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