XANES analysis of tribo-chemical and thermal films generating from some organic polysulfides

Abstract

X-ray absorption near edge structure (XANES) spectroscopy has been firstly used to characterize the chemical nature of tribochemical and thermal films generated from alkyl, benzyl and acylcontaining organic polysulfides. It has been found that the thermal films generated from these polysulfides are mainly composed of FeSO 4 , and alkyl disulfides also exist in the subsurface and bulk of thermal films generated from acyl-containing polysulfides. Under tribochemical conditions, the composition of film is dependent on the molecular structure of the additives. Namely, the tribochemical film generated from alkyl polysulfide is composed of alkyl disulfide in the out surface, a mixture of FeSO 4 , FeS 2 and sulfoxide in the subsurface, and FeSO 4 in the bulk; the composition of the tribochemical film for benzyl polysulfide consists of FeSO 4 in the out surface, while the composition in subsurface and bulk is the same as the alkyl polysulfide. For acyl-containing polysulfides, the tribochemical films consist of alkyl disulfide in the out surface, and FeS 2 in the subsurface and bulk.

The tribological study of novel phosphorous–nitrogen type phosphoramidate additives in rapeseed oil

“…[14][15][16][17][18][19] A large number of studies about XANES analysis of tribofilm have been performed by many researchers, especially on phosphorous-and sulfur-containing additives. [19][20][21][22][23] In this study, two novel phosphorous-nitrogen (P-N) type phosphoramidate derivatives, dibutyl octadecylphosphoramidate (coded DBOP) and dimethyl 4-dodecylphenylphosphoramidate (coded DMDP), were synthesized and applied as lubricant additives in RSO. Using a four-ball machine and standard method, the tribological behaviors of these additives in RSO were compared with commercial lubricant additives dodecan-1-aminium butyl 7-methyloctyl phosphate (coded T308B) and dibutyl phosphonate (coded T304).…”

Tribological behaviors of three novel imidazoline-type thiadiazole derivatives as multifunctional lubricant additives in biodegradable lithium grease

“…Generally, the purpose of EP additive is to provide added wear protection and anti-seizing properties to both the metallic surface and the lubricant under higher loads and higher temperatures, and sulfur is one of the most widely used elements in EP lubricant additives. 38 The EP behaviors of grease samples containing these thiadiazole derivatives are presented in Figures 7 and 8, respectively, along with the result of the BG. In comparison with the BG, the P B value is increased using these derivatives as EP additives at a given additive concentration, and the derivative OIB is better than other derivatives in enhancing the maximum non-seizure load of the BG.…”

XANES characteristics of tribofilms generated by dithiophosphate additive in water at different test temperatures and durations

“…The assignment of the fine structure in XANES was obtained by using the spectra of model compounds obtained by the authors or from previously published data. [16,17] …”

“…[16]. The process was as follows: the balls were put into the 5.0% additive-containing lubricant, keeping reaction for 6 h at 40, 60 and 80…”