Ashless and non-corrosive disulfide compounds as excellent extreme pressure additives in naphthenic oil

Chiu Ling Ong, Xuefeng Jiang, Joon Ching Juan, Nader Ghaffari Khaligh, Thorsten Heidelberg

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

Medium chain chlorinated paraffin (MCCP) and zinc dialkyl dithiophosphate (ZDDP) are widely used as extreme pressure (EP) additives in metalworking fluids (MWFs). Currently, sulfur-based EP additives are found to be more environmentally friendly and biodegradable. Although naphthenic base oil (NBO) is suitable to be used in MWFs due to its low pour point and better emulsified ability, there is a lack of study on the sulfur additives in this type of oil. In this study, two organo disulfides compounds namely dibenzyl disulfide (DBDS) and dioctyl disulfide (DODS) have been synthesized as EP additives. These DBDS and DODS demonstrate an excellent EP performance, non-corrosive, ashless, and good anti-wear (AW) properties in NBO. The DBDS shows 1961 N (EP value) and 6 mm2 (AW scar area) in NBO, which is superior to DODS, MCCP and ZDDP. This is due to the formation of sulfur-based tribofilm on the interface that acts as a protective sulfur layer thus, enhancing the property of EP.

Original languageEnglish
Article number118553
JournalJournal of Molecular Liquids
Volume351
DOIs
StatePublished - 1 Apr 2022

Keywords

  • Ashless
  • Extreme pressure
  • Non-corrosive
  • Sulfur additives
  • Symmetrical disulfide

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