Special Issue "Lubricant Additives"

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Chemistry".

Deadline for manuscript submissions: closed (5 March 2017).

Special Issue Editor

Prof. Ichiro Minami
E-Mail Website
Guest Editor
Division of Machine Elements, Luleå University of Technology, 97187 Luleå, Sweden
Interests: chemical structure of surface; chemical analysis f surface; chemical reactions to deposit a coating; mechanical properties (lubrication) of surface
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Special Issue Information

Dear Colleagues,

Lubricants play significant roles in machine elements through reducing friction and wear, in order that they function efficiently. The phenomenon of improved lubricity using additives was first reported mid-20th Century. Since then, R&D activities for lubricant additives have been performed on a trial and error basis. Today, various additives are applied in lubricants to improve the total performances of lubrication systems. Different types of additives are well-combined in an empirical way, to achieve the multi-functionalities in practical applications. This Special Issue focuses on recent challenges in additive technologies of lubricants using specific scientific approaches toward advanced lubricant chemistry. Mechanistic investigations on optimal molecular designs of additives are also within the scope of the issue. We look forward to receiving your original work having clear strategies with scientific tools and/or theorem for additive technologies.

Prof. Dr. Ichiro Minami
Guest Editor

Manuscript Submission Information

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Keywords

  • tribology,
  • tribo-chemistry,
  • lubricant chemistry,
  • lubrication mechanism,
  • molecular design,
  • extreme pressure additives,
  • antiwear additives,
  • friction modifiers,
  • viscosity modifiers,
  • antifoams,
  • detergents,
  • dispersants,
  • antioxidants,
  • corrosion/rust inhibitors

Published Papers (3 papers)

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Research

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Open AccessFeature PaperArticle
Formation of Boundary Film from Ionic Liquids Enhanced by Additives
Appl. Sci. 2017, 7(5), 433; https://doi.org/10.3390/app7050433 - 26 Apr 2017
Cited by 5
Abstract
Room temperature ionic liquids (RTILs) have several properties that make them interesting candidates as base fluids for extreme conditions. However, a lack of compatibility with tribo-improving additives combined with an often overly aggressive nature is limiting their use as base fluids. To overcome [...] Read more.
Room temperature ionic liquids (RTILs) have several properties that make them interesting candidates as base fluids for extreme conditions. However, a lack of compatibility with tribo-improving additives combined with an often overly aggressive nature is limiting their use as base fluids. To overcome these drawbacks, hydrocarbon-imitating RTIL base fluids have recently been developed. In this study, the effects of several common additives in the novel RTIL (P-SiSO) were examined by laboratory tribotesting. A reciprocating steel-steel ball-on-flat setup in an air atmosphere was used, where the lubricant performance was evaluated over a range of loads and temperatures. Surface analyses after testing were carried out using optical profilometry, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Neat P-SiSO displayed high performance in the tribotests. At an elevated load and temperature, a shift in lubrication mode was observed with an accompanying increase in friction and wear. Surface analysis revealed a boundary film rich in Si and O in the primary lubrication mode, while P was detected after a shift to the secondary lubrication mode. An amine additive was effective in reducing wear and friction under harsh conditions. The amine was determined to increase formation of the protective Si–O film, presumably by enhancing the anion activity. Full article
(This article belongs to the Special Issue Lubricant Additives)
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Open AccessArticle
Oxidation Products of Ester-Based Oils with and without Antioxidants Identified by Stable Isotope Labelling and Mass Spectrometry
Appl. Sci. 2017, 7(4), 396; https://doi.org/10.3390/app7040396 - 16 Apr 2017
Cited by 4
Abstract
As lubricants with a high thermo-oxidative stability such as synthetic esters are gaining more importance in the lubricant market, a detailed knowledge regarding their oxidative degradation behaviour is of high importance. In order to reveal their degradation products and processes, a novel approach [...] Read more.
As lubricants with a high thermo-oxidative stability such as synthetic esters are gaining more importance in the lubricant market, a detailed knowledge regarding their oxidative degradation behaviour is of high importance. In order to reveal their degradation products and processes, a novel approach combining artificial alteration, isotope labelling based on oxidation with 16O2 and 18O2, and mass spectrometry (MS), was applied to a bis(2-ethylhexyl) adipate base oil. The degradation products such as 2-ethylhexanol and its monoesters with short-chain fatty acids pinpointed the C–O ester bond as the site prone to oxidative attack, allowing the collection of information about the oxidation mechanisms. Furthermore, the influence of the antioxidant (AO) 4,4′-methylene-bis(2,6-di-tert-butylphenol) as an additive on the oxidation behaviour and resulting products was studied: blends containing AO showed a remarkably higher resistance against oxidation. However, similar degradation products were obtained after AO depletion and without AO. AO cleavage occurred at the carbon atom that bridges the phenols to give 2,6-di-tert-butyl-p-benzoquinone and 3,5-di-tert-butyl-4-hydroxybenzoic acid. By applying the isotope labelling approach, sites of preferential oxidative cleavage and hence differentiation of the origin of oxygen atoms—either from the atmosphere or from base oil components—can be unambiguously related in oxygen-containing base oils, as well as in blends with additives. Full article
(This article belongs to the Special Issue Lubricant Additives)
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Review

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Open AccessReview
Molecular Science of Lubricant Additives
Appl. Sci. 2017, 7(5), 445; https://doi.org/10.3390/app7050445 - 28 Apr 2017
Cited by 22
Abstract
This review aims at introducing an engineering field of lubrication to researchers who are not familiar with tribology, thereby emphasizing the importance of lubricant chemistry in applied science. It provides initial guidance regarding additive chemistry in lubrication systems for researchers with different backgrounds. [...] Read more.
This review aims at introducing an engineering field of lubrication to researchers who are not familiar with tribology, thereby emphasizing the importance of lubricant chemistry in applied science. It provides initial guidance regarding additive chemistry in lubrication systems for researchers with different backgrounds. The readers will be introduced to molecular sciences underlying lubrication engineering. Currently, lubricant chemistry, especially “additive technology”, looks like a very complicated field. It seems that scientific information is not always shared by researchers. The cause of this is that lubrication engineering is based on empirical methods and focuses on market requirements. In this regard, engineering knowhow is held by individuals and is not being disclosed to scientific communities. Under these circumstances, a bird’s-eye view of lubricant chemistry in scientific words is necessary. The novelty of this review is to concisely explain the whole picture of additive technology in chemical terms. The roles and functions of additives as the leading actors in lubrication systems are highlighted within the scope of molecular science. First, I give an overview of the fundamental lubrication model and the role of lubricants in machine operations. The existing additives are categorized by the role and work mechanism in lubrication system. Examples of additives are shown with representative molecular structure. The second half of this review explains the scientific background of the lubrication engineering. It includes interactions of different components in lubrication systems. Finally, this review predicts the technical trends in lubricant chemistry and requirements in molecular science. This review does not aim to be a comprehensive chart or present manufacturing knowhow in lubrication engineering. References were carefully selected and cited to extract “the most common opinion” in lubricant chemistry and therefore many engineering articles were omitted for conciseness. Full article
(This article belongs to the Special Issue Lubricant Additives)
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