Phosphonium-based ionic liquids as additives in calcium/lithium greases

• Type: Article in International Scientific Journal
• Date: 2021

Authors

Tuero, AG (Author) Other; Bartolome, M (Author) Other; Goncalves, D (Author) Other; Viesca, JL (Author) Other; Fernandez Gonzalez, A (Author) Other; Jorge Seabra (Author) FEUP; Battez, AH (Author) Other

Journal

Title: Journal of Molecular Liquids

Vol. 338

ISSN: 0167-7322

Publisher: Elsevier

Indexing

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Other information

Authenticus ID: P-00V-2A2

DOI: 10.1016/j.molliq.2021.116697

Abstract (EN): This work studies the performance of three phosphonium-based ionic liquids ([P-6,P-6,P-6,P-14][BEHP], [P-6,P-6,P-6,P-14] [TCM] and [P-6,P-6,P-6,P-14][DEC]) when used separately as additives on the thermal conductivity, thermal stability and tribological properties of two non-additised greases (a lithium-based and a calcium-based grease). The main results confirmed that the [P-6,P-6,P-6,P-14][TCM] improved the thermal stability of both greases. Only the mixtures G1 + 5%[P-6,P-6,P-6,P-14][BEHP] and G2 + 5%[P-6,P-6,P-6,P-14][TCM] showed a slight increase in thermal conductivity. In general, the addition of the ILs to the lithium-based grease increased the friction coefficient in both the four-ball tests and the reciprocating tests, while the friction coefficient decreased with the addition of the ILs to the calcium-based grease in the four-ball tests. The addition of the [P-6,P-6,P-6,P-14][BEHP] and [P-6,P-6,P-6,P-14][TCM] improved the antiwear behavior of the lithium-based grease under both tribological tests, whereas all the ionic liquids worsened the antiwear behavior of the calcium-based grease in the four-ball tests. The [P-6,P-6,P-6,P-14][BEHP] had the best antiwear behavior due to the higher interaction of phosphorous with the metal surface. A possible interference of the calcium thickener with the ionic liquid-metal surface interaction was found, resulting in lower antiwear behavior of the mixtures with the calcium-based grease. (C) 2021 The Author(s). Published by Elsevier B.V.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 11