Hydrolytic stability of S‐hydroxyethyl N,N‐dialkyl dithiocarbamate‐derived borates and their tribological behavior as additives in PAO

Abstract

Purpose

The purpose of this paper is to investigate the hydrolytic stability of several S‐hydroxyethyl N,N‐dialkyl dithiocarbamate‐derived borates SNB1, SNB2, and SNB3, to evaluate their tribological performances used as additives in polyalpha olefins (PAO), and to explore the tribochemical action mechanism.

Design/methodology/approach

First, the three additives are synthesized and characterized. Second, the hydrolytic stabilities of the three compounds are investigated. As the third step, they are, respectively, added to PAO and a series of samples with different concentrations of the additives in PAO are prepared, respectively. Their tribological properties are evaluated with two types of four‐ball machines, and then the wear scars were observed using a JSM‐5600LV scanning electron microscope. Finally, the elements on the worn surface are analyzed with a X‐ray photoelectron spectroscope (XPS).

Findings

The three novel compounds possess relatively good hydrolytic stabilities, excellent anti‐wear (AW) performances, friction reduction properties, and load‐carrying capacity. There is an optimum concentration of each of the three additives for their AW properties. According to the XPS analytical results, a boundary lubrication protective film has formed during friction consisting of FeSO₄ film, Fe₂O₃ film, and the complicated adsorption film composed of N‐containing organic compounds. In the protective films, a large quantity of compounds containing element B is not found.

Research limitations/implications

The antioxidation performances and the anticorrosion properties are not estimated.

Practical implications

Three novel AW/extreme pressure (EP) additives are synthesized, and may be they have the potential industrial application as AW/EP additives in lubricating oil.

Originality/value

The present work provides a research method of N,S‐containing organic borates as lubricating oil additives.

Citation

Sun, Y., Hu, L. and Xue, Q. (2010), "Hydrolytic stability of S‐hydroxyethyl N,N‐dialkyl dithiocarbamate‐derived borates and their tribological behavior as additives in PAO", Industrial Lubrication and Tribology, Vol. 62 No. 2, pp. 70-77. https://doi.org/10.1108/00368791011025601