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Homayoun, M.-R., Golchin, A. & Emami, N. (2018). Effect of Hygrothermal Ageing on Tribological Behaviour of PTFE-Based Composites. Lubricants, 6(4), Article ID 103.
Open this publication in new window or tab >>Effect of Hygrothermal Ageing on Tribological Behaviour of PTFE-Based Composites
2018 (English)In: Lubricants, E-ISSN 2075-4442, Vol. 6, no 4, article id 103Article in journal (Refereed) Published
Abstract [en]

The present study investigates the influence of hygrothermal ageing on the tribological behaviour of polytetrafluoroethylene (PTFE) polymer composites. Three PTFE composites along with unfilled PTFE were tested in sliding contact against Inconel 625 (a Ni-based alloy) plates in both dry and water-lubricated conditions, utilising a unidirectional pin-on-disc tribometer. The tribo-tests were performed at a constant sliding speed of 0.13 m/s with a normal load of 84N providing an apparent contact pressure of 5 MPa. Hygrothermal conditioning was carried out at two different temperatures, and the water absorption evolution and kinetic parameters were estimated. Various characterisation methods were used to identify the wear mechanisms and influence of hygrothermal ageing on the degradation of the filler/matrix. The different tribological behaviour for different PTFE composites was observed within the ageing timeframe. The wear resistance of the fibre-filled samples was reduced compared to the non-aged ones over the ageing timeframe. However, the friction and wear resistance of the bronze-filled PTFE were enhanced by hygrothermal ageing.

Place, publisher, year, edition, pages
MDPI, 2018
Keywords
hygrothermal ageing, PTFE, friction, wear
National Category
Mechanical Engineering Materials Engineering Composite Science and Engineering Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-71930 (URN)10.3390/lubricants6040103 (DOI)000455618500019 ()2-s2.0-85059383793 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-02-01 (inah)

Available from: 2018-12-06 Created: 2018-12-06 Last updated: 2019-02-01Bibliographically approved
Vadivel, H., Golchin, A. & Emami, N. (2018). Tribological behaviour of carbon filled hybrid UHMWPE composites in water. Tribology International, 124, 169-177
Open this publication in new window or tab >>Tribological behaviour of carbon filled hybrid UHMWPE composites in water
2018 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 124, p. 169-177Article in journal (Refereed) Published
Abstract [en]

In this study, newly developed hybrid composites with Ultra High Molecular Weight Polyethylene (UHMWPE) as base polymer and Graphene Oxide (GO), Nano Diamonds (ND) and Short Carbon Fibres (SCF) as fillers were manufactured. The tribological performance of these composites in a water lubricated sliding contact and the effect of inclusion of the fillers on the mechanical and thermal properties of the composites were investigated. The resulting hybrid composite formed by using the fillers and the base polymer displayed low friction coefficient and high wear resistance. Compared to unfilled UHMWPE, composite with all the fillers incorporated had 21% smaller friction coefficient and 15% less wear.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-68231 (URN)10.1016/j.triboint.2018.04.001 (DOI)000432769800015 ()2-s2.0-85045421012 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-04-16 (andbra)

Available from: 2018-04-06 Created: 2018-04-06 Last updated: 2018-06-13Bibliographically approved
Ytrehus, J. D., Taghipour, A., Golchin, A., Saasen, A. & Prakash, B. (2017). The Effect of Different Drilling Fluids on Mechanical Friction. Journal of energy resources technology, 139(3), Article ID 034502.
Open this publication in new window or tab >>The Effect of Different Drilling Fluids on Mechanical Friction
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2017 (English)In: Journal of energy resources technology, ISSN 0195-0738, E-ISSN 1528-8994, Vol. 139, no 3, article id 034502Article in journal (Refereed) Published
Abstract [en]

A very important aspect in highly inclined wellbores is the mechanical friction. For extended reach drilling (ERD) and through tubing extended reach drilling (TTERD) this can be a limiting factor. Friction caused by the contact between the drill string and the well casing or borehole is dependent on the drilling weight and fluid properties. Drilling fluids play an important role in determining mechanical friction. The use of oil-based drilling fluids with higher lubricity can reduce torque and drag behavior and minimize stick and slip. Reducing mechanical friction will improve drilling efficiency in general, and will in particular enable longer reach for ERD wells. This paper presents results from experimental laboratory tests where the mechanical friction has been investigated. Friction behavior was investigated for different drilling fluids; water-based and oil-based drilling fluids both with and without solid particles. A pin on disk setup was used for these experiments where a spherical ended steel pin was slid against a rotating disk made of granite. The test results show that the mechanical friction in general is smaller with oil-based than water-based drilling fluids in the presence of solid particles.

Place, publisher, year, edition, pages
The American Society of Mechanical Engineers, 2017
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-63243 (URN)10.1115/1.4035951 (DOI)000399077300026 ()2-s2.0-85020882541 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-05-05 (andbra)

Available from: 2017-05-05 Created: 2017-05-05 Last updated: 2018-11-20Bibliographically approved
Golchin, A., Villain, A. & Emami, N. (2017). Tribological Behaviour of Nanodiamond Reinforced UHMWPE in Water-Lubricated Contacts. Tribology International, 110, 195-200
Open this publication in new window or tab >>Tribological Behaviour of Nanodiamond Reinforced UHMWPE in Water-Lubricated Contacts
2017 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 110, p. 195-200Article in journal (Refereed) Published
Abstract [en]

In this study, the tribological behaviour of nanodiamond reinforced UHMWPE composites was investigated in water-lubricated sliding contacts. A significant reduction of 72% in wear and 24% in friction of UHMWPE was observed with incorporation of 1 wt% nanodiamond in the polymer matrix. Various bulk and surface characterization techniques were utilised to reveal the main mechanisms involved in the friction and wear response of the polymeric materials. The improved tribological behaviour of UHMWPE upon incorporation of various loadings of nanodiamond in the polymer matrix was mainly attributed to the boundary lubricating action of nanodiamonds and the polishing effect of the nanodiamond reinforced UHMWPE composites on the counter surfaces in water-lubricated sliding contacts.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-61456 (URN)10.1016/j.triboint.2017.01.016 (DOI)000398871700021 ()2-s2.0-85013778906 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-03-09 (andbra)

Available from: 2017-01-16 Created: 2017-01-16 Last updated: 2018-09-13Bibliographically approved
Vadivel, H., Golchin, A. & Emami, N. (2017). Tribological performance and thermal characteristics of UHMWPE multifunctional hybrid composites. In: : . Paper presented at 6th European Conference on Tribology, ECOTRIB.
Open this publication in new window or tab >>Tribological performance and thermal characteristics of UHMWPE multifunctional hybrid composites
2017 (English)Conference paper, Poster (with or without abstract) (Refereed)
National Category
Materials Engineering Composite Science and Engineering Mechanical Engineering
Identifiers
urn:nbn:se:ltu:diva-71937 (URN)
Conference
6th European Conference on Tribology, ECOTRIB
Available from: 2018-12-06 Created: 2018-12-06 Last updated: 2018-12-06
Golchin, A., Wikner, A. & Emami, N. (2016). An Investigation into Tribological Behaviour of Multi-Walled Carbon Nanotube/Graphene Oxide Reinforced UHMWPE in Water Lubricated Contacts (ed.). Paper presented at . Tribology International, 95, 156-161
Open this publication in new window or tab >>An Investigation into Tribological Behaviour of Multi-Walled Carbon Nanotube/Graphene Oxide Reinforced UHMWPE in Water Lubricated Contacts
2016 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 95, p. 156-161Article in journal (Refereed) Published
Abstract [en]

In this study, the influence of incorporation of carbon based nano fillers, namely multi-walled carbon nanotubes and graphene oxide on the tribological behaviour of ultra-high molecular weight polyethylene was investigated in water lubricated sliding contacts. Further investigations were carried out to study the influence of γ-irradiation and hygrothermal aging on the friction and wear response of the polymeric materials. It was found that regardless of the treatment, GO/MWNT reinforced composites consistently exhibited a lower friction and higher wear resistance in comparison to the unfilled UHMWPE. This was mainly attributed to the lubricating action of the carbonaceous nano fillers in water lubricated sliding contacts.

National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-11815 (URN)10.1016/j.triboint.2015.11.023 (DOI)000371103400018 ()2-s2.0-84948781740 (Scopus ID)ad495bba-91f4-4cac-8ac3-1aa4eefe38cf (Local ID)ad495bba-91f4-4cac-8ac3-1aa4eefe38cf (Archive number)ad495bba-91f4-4cac-8ac3-1aa4eefe38cf (OAI)
Note
Validerad; 2015; Nivå 2; 20151119 (aragol)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Golchin, A., Friedrich, K., Noll, A. & Prakash, B. (2015). Influence of Counter Surface Topography on the Tribological Behaviour of Carbon-filled PPS Composites in Water (ed.). Paper presented at International Tribology Conference : 16/09/2015 - 20/09/2015. Paper presented at International Tribology Conference : 16/09/2015 - 20/09/2015.
Open this publication in new window or tab >>Influence of Counter Surface Topography on the Tribological Behaviour of Carbon-filled PPS Composites in Water
2015 (English)Conference paper, Oral presentation only (Refereed)
Abstract [en]

This study is aimed at investigating the influence of counter surfaces’ topography on tribological behaviour of several carbon-filled polyphenylene sulfide (PPS) composites in water lubricated contacts. The results of this study showed significant increase in wear rate of pure, graphite and/or multi-walled carbon nanotubes filled PPS composites with increase in mean slope of profile along the sliding direction (Δαy). This is while short carbon fiber (SCF) filled PPS composites exhibited 1-3 orders of magnitude lower wear rate with little dependence on counter surface roughness characteristics. Among the roughness parameters studied, Rpk and lay orientation played a more significant role in friction, and Rpk and Δαy were found to correlate best with the wear rate of the composites not containing SCF in their matrices.Keywords: Polyphenylene sulfide, Roughness; Polymer; Friction; Wear.

National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-27038 (URN)05823144-fd72-4400-bcec-46a42038fe8a (Local ID)05823144-fd72-4400-bcec-46a42038fe8a (Archive number)05823144-fd72-4400-bcec-46a42038fe8a (OAI)
Conference
International Tribology Conference : 16/09/2015 - 20/09/2015
Note
Godkänd; 2015; 20150923 (aragol)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-05-28Bibliographically approved
Golchin, A., Friedrich, K., Noll, A. & Prakash, B. (2015). Influence of counter surface topography on the tribological behaviour of carbon-filled PPS composites in water (ed.). Paper presented at . Tribology International, 88, 209-217
Open this publication in new window or tab >>Influence of counter surface topography on the tribological behaviour of carbon-filled PPS composites in water
2015 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 88, p. 209-217Article in journal (Refereed) Published
Abstract [en]

This study is aimed at investigating the influence of counter surfaces’ topography on tribological behaviour of several carbon-filled polyphenylene sulfide (PPS) composites in water lubricated contacts. The results of this study showed significant increase in wear rate of pure, graphite and/or multi-walled carbon nanotubes filled PPS composites with increase in mean slope of profile along the sliding direction (Δαy). This is while SCF filled PPS composites exhibited 1–3 orders of magnitude lower wear rate with little dependence on counter surface roughness characteristics. Among the roughness parameters studied, Rpk and lay orientation played a more significant role in friction, and Rpk and Δαy were found to correlate best with the wear rate of the composites not containing SCF in their matrices.

National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-5532 (URN)10.1016/j.triboint.2015.03.023 (DOI)000355571500024 ()2-s2.0-84926648052 (Scopus ID)3a9335c1-5f6f-4870-9b88-366d02bc13e5 (Local ID)3a9335c1-5f6f-4870-9b88-366d02bc13e5 (Archive number)3a9335c1-5f6f-4870-9b88-366d02bc13e5 (OAI)
Note
Validerad; 2015; Nivå 2; 20150325 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Golchin, A. (2015). Polymeric Materials for Bearing Applications: Tribological Studies in Lubricated Conditions (ed.). (Doctoral dissertation). Paper presented at . : Luleå tekniska universitet
Open this publication in new window or tab >>Polymeric Materials for Bearing Applications: Tribological Studies in Lubricated Conditions
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

One of the most important demands in hydropower and other industries today stems from the emphasis on preserving the environment. Usage of mineral and synthetic oils in sliding bearings of hydropower plants raises concerns about the environmental impact of these lubricants in case of spillage into downstream water. These concerns have led to attempts in using water as lubricant and the concept of oil-free systems in hydropower generation. Realization of this concept however poses many challenges including the choice of bearing materials and this necessitated research pertaining to the tribological behaviour of polymers in lubricated conditions. In this work, several studies have been carried out in order to obtain an insight into polymers’ tribological performance and associated mechanisms in the presence of lubricants.Extensive tribological studies on several unfilled polymers in water lubricated contacts demonstrated the superior wear resistance of UHMWPE. It was also found that the frictional behaviour of the unfilled polymers was influenced by their water contact angle and relative energy difference with regard to water.Studies on the effect of counter surface roughness characteristics on tribological behaviour of polymeric materials revealed their significant influence on friction and wear behaviour of polymer-metal contacts. Using a small scale journal bearing configuration, it was found that dynamic friction of polymer bearings can be significantly reduced using a shaft of reduced surface roughness. However, depending on the bearing material, this can adversely affect the material’s breakaway frictional response and thereby increase the torque required for machine start-up; a critical issue in applications such as pumped storage hydropower plants. Further studies using a pin on plate configuration revealed that variations in surface roughness characteristics of the metallic counter surfaces can significantly alter the wear resistance of the polymeric materials which cannot modify the topography of the counter surfaces in a tribological contact.Investigations regarding the influence of incorporation of various micro/nano carbon based fillers/reinforcements in the polymer matrix revealed their great potential for enhancing the friction and wear behaviour of the polymer composites. However these effects have been found to be strongly influenced by presence/absence of other reinforcements in the polymer matrix and/or by alterations in the operating conditions.Application of polymers as bearing lining materials also exhibits the potential of enhancing the performance of oil lubricated bearings. Therefore a part of this work was aimed at investigating the tribological characteristics of several polytetrafluoroethylene based materials at the onset of sliding (breakaway) at various pressures and temperatures. The results of this study showed dramatic reduction in breakaway friction using PTFE based materials in comparison to the conventional Babbitt (white metal) bearing lining material utilized in oil-lubricated sliding bearings of hydropower plants.

Place, publisher, year, edition, pages
Luleå tekniska universitet, 2015
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-17415 (URN)351ad789-ed1c-4d6f-8b02-e25a766913e4 (Local ID)978-91-7583-296-8 (ISBN)978-91-7583-297-5 (ISBN)351ad789-ed1c-4d6f-8b02-e25a766913e4 (Archive number)351ad789-ed1c-4d6f-8b02-e25a766913e4 (OAI)
Note
Godkänd; 2015; 20150401 (aragol)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-05-28Bibliographically approved
Ytrehus, J. D., Taghipour, A., Golchin, A., Prakash, B. & Saasen, A. (2015). The effect of different oil based drilling fluids on mechanical friction (ed.). In: (Ed.), (Ed.), Proceedings of the ASME 34th International Conference on Ocean, Offshore and Arctic Engineering - 2015: presented at ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering; May 31 - June 5, 2015, St. John's, Newfoundland, Canada. Paper presented at ASME International Conference on Ocean, Offshore and Arctic Engineering : 31/05/2015 - 05/06/2015. New York: American Society of Mechanical Engineers, 10 : Petroleum technology, Article ID OMAE2015-41896.
Open this publication in new window or tab >>The effect of different oil based drilling fluids on mechanical friction
Show others...
2015 (English)In: Proceedings of the ASME 34th International Conference on Ocean, Offshore and Arctic Engineering - 2015: presented at ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering; May 31 - June 5, 2015, St. John's, Newfoundland, Canada, New York: American Society of Mechanical Engineers , 2015, Vol. 10 : Petroleum technology, article id OMAE2015-41896Conference paper, Published paper (Refereed)
Abstract [en]

A very important aspect in highly inclined wellbores is the mechanical friction. For extended reach drilling (ERD) and through tubing extended reach drilling (TTERD) this can be a limiting factor. Friction caused by the contact between the drill string and the well casing or borehole is dependent to the drilling weight and fluid properties. Drilling fluids play an important role on mechanical friction and using oil based drilling fluids with higher lubricity can reduce torque and drag behavior and minimize stick and slip. Reducing mechanical friction will improve drilling efficiency in general, and will in particular enable longer reach for ERD wells.This paper presents results from experimental laboratory tests where mechanical friction has been investigated. The experiments have been conducted as part of a project in the Tribolab at Luleå University of Technology in cooperation with Det norske Oljeselskap.Friction behavior has been investigated for different drilling fluids; water based and oil based drilling fluids both with and without solid particles. A pin on disc setup was used for these experiments where a spherical steel pin was sliding on a rotational disc made of granite. Friction force has been measured in constant sliding speed and in presence of particles in wet condition. The test results show that mechanical friction in general is smaller with oil based than water based drilling fluids in the presence of solid particles. In addition, the friction coefficient increases when solid particles were added to the lubricants.Such experiments in a tribology laboratory are important to identify the effect of drilling fluids on mechanical friction from a basic point of view and isolated from all other wellbore parameters. It is interesting to monitor if the results from this setup can have quantitative relevance also for field situations and such comparison should be done as follow up. Test results and the experimental approach could therefore be of value for any one working with drilling and well construction.

Place, publisher, year, edition, pages
New York: American Society of Mechanical Engineers, 2015
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-34999 (URN)10.1115/OMAE2015-41896 (DOI)9575267d-aafc-4272-a8e4-598d32836dd1 (Local ID)978-0-7918-5658-1 (ISBN)9575267d-aafc-4272-a8e4-598d32836dd1 (Archive number)9575267d-aafc-4272-a8e4-598d32836dd1 (OAI)
Conference
ASME International Conference on Ocean, Offshore and Arctic Engineering : 31/05/2015 - 05/06/2015
Note
Validerad; 2016; Nivå 1; 20150609 (aragol)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-05-28Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-8285-9841

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