Synergism in the Action of a Composition Consisting of Ashless Sulfur-Containing Compounds as an Antiwear Additive to Lu
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rgism in the Action of a Composition Consisting of Ashless Sulfur-Containing Compounds as an Antiwear Additive to Lubricants V. A. Zolotova and V. N. Bakuninb, * a
25th State Research Institute of Chemmotology, Russian Federation Defense Ministry, Moscow, 121467 Russia b All-Russia Research Institute for Oil Refining, Moscow, 111116 Russia *e-mail: [email protected] Received March 11, 20; revised May 6, 2020; accepted May 6, 2020
Abstract—Compositions of ashless thio compounds in mixtures with mineral oil and metal-containing detergents were tested as antiwear additives representing variants of model engine oil compositions. The tribological activity for both fresh and oxidized mixtures, in comparison with the efficiency of the industrial additive zinc dialkyldithiophosphate, was investigated using different tribometers that realize different wear conditions for friction pairs. Synergy is noted in the antiwear action of amine salt compositions of dialkyldithiophosphoric acid and methylene-bis-dibutyldithiocarbamate, which in turn ensures the ecological safety of lubricants—low sulfate ash and phosphorous contents. Keywords: organic element compounds, lubricants, additives, antiwear properties, tribometer, tribolayers, coefficient, wear surface DOI: 10.3103/S1068366620040157
INTRODUCTION The environmental safety of the automobile operation is ensured by observing harmful emission standards for the exhaust gases of internal combustion engines. The level of harmful emissions is reduced by using special equipment that recirculates and catalytically afterburns exhaust gases and filters soot particles. Corresponding requirements are imposed on the composition and properties of motor oils with a minimum permissible content of sulfate ash, phosphorus, and sulfur [1, 2]. The main contribution to the sulfate ash content in oil is determined by the calcium-containing detergents in its composition with zinc dialkyldithiophosphate. An increased sulfate ash content leads to an increase in the amount of deposits in the exhaust gas recirculation system and intensive clogging of pores of the particulate filter; an increased phosphorus content leads to a decrease in the efficiency of the selective neutralizer. Instead of zinc salt of dialkyldithiophosphoric acid as an antiwear additive, the possibility of using compounds not containing metal atoms but having a low content of phosphorus atoms is considered [3]. Objective—to study the antiwear properties of the composition of organic element thio compounds and determine the synergistic effect of their composition as an antiwear additive to motor oils.
MATERIALS AND METHODS The antiwear properties were studied in fresh and transformed compositions as models working as a result of laboratory high-temperature (180°C) catalytic (Cu) oxidation [4]; the compositions contained ashless potential antiwear agents mixed with I-20 oil: a dialkyldithiocarbamic acid derivative—methylene bisdibutyl dithiocarbamate (Additin RC 6340), which contains no phosphorus atoms, and dialkyl dithiophosphori
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