Influence of acid-base and adsorptive characteristics of disperse aluminum modified by ammonium compounds on antifriction effect in lubricant

25th International Conference on Vacuum Technique and Technology

Syrkov, A.G.^1 ; Silivanov, M.O.^1 ; Kabirov, V.R.^1 ; Pleskunov, I.V.^2

Department of General and Technical Physics, Saint Petersburg Mining University, Saint Petersburg

199106, Russia^1

Representative Office of IMC Montan Company in the Republic of Belarus, IMC Montan, Minsk

220005, Belarus^2

关键词: Acid dissociation constants;    Antifriction effect;    Distribution curves;    Hydrocarbon radicals;    Oil based lubricant;    Quaternary ammonium compound;    Spectrophotometric analysis;    Water-repellent properties;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/387/1/012076/pdf
DOI  :  10.1088/1757-899X/387/1/012076

来源: IOP

【 摘 要 】

The article analyses the acid-base and adsorptive characteristics of the metal samples obtained using method of layering of different-sized molecules of quaternary ammonium compounds (QAC). The method allows to vary the hydrophilic-lipophilic, antifriction and other properties of commonly used disperse metals. The method includes the process of adsorption of reagents such as QAC based triamon (C1-C2) and alkamon (C16-C18), which have very different in length hydrocarbon radical at nitrogen atom. The acid-base properties of modified disperse aluminum were studied using Hammett indicator method and it has been established that there is a change in the quantity of the donor-acceptor centers of the powder caused by the adsorption of QAC. Spectrophotometric analysis of surface centers was performed using the Hammett indicators within the range of pKa values from -0.3 to 14.2. The distribution curves of the active adsorption centers of aluminum-based powders were plotted against the acid dissociation constant (acid strength - pKa) of the indicators. A sharp decrease is observed in the number of centers in the Lewis acid sites region for the Al/(A+T) sample with co-adsorbed alkamone (A) and triamon (T). In addition, significant decrease in antifriction and water-repellent properties of the sample Al/T/A (consistent treatment of metal in vapor of T and A) in comparison with sample Al/(A+T) is explained by the increase of Bronsted base centers with pKa = 9.5 and less intense interaction of QAC with Lewis acid centers with pKa = 14.2.The following pattern was revealed: increase in the antifriction effect of oil based lubricants is accompanied by reduction of the Bronsted centers content and as a rule by the decrease of acidity function (H) of the surface of the QAC-modified Al-powder which was added to the lubricant.