Малозольные моторные масла: технологии и тенденции применения
V. A. Zolotov, V. N. Bakunin (FAE «The 25th State Research Institute of Chemmotology of Ministry of Defence of the Russian Federation», «LLC-International», Moscow, Russia)
Keywords: diesel, gasoline engine, engine oils, sulfate ash, properties, specification, test method.
Abstract. Analytical information is presented on the development and implementation of low- and ash-free motor oils in the specifications for promising automotive engines, taking into account global trends in the development of engine building. The technologies of ash-free alkaline number boosters of various composition and structure in motor oils, the features of the use of oils of new categories, including restrictions on the content of sulphate ash in them, are considered. The improvement of the design of these engines, the expansion of the range of their operating conditions determines the specifics of the requirements for the physico-chemical properties of the engine oils used, which in turn provides for changes in the chemical composition of the latter.
The increased content of these elements and sulfate ash has a negative impact on the efficiency of the systems for cleaning and neutralizing harmful exhaust gas particles, and sulfate ash additionally negatively affects the formation of deposits in the zone of the cylinder piston group, on the blades and in the turbocharger nozzle, as well as on valve seats. The necessary neutralizing oil reserve, expressed by the value of its base number, is provided by the use of, in particular, low-ash magnesium sulfonates, amino derivatives of ash-free boosters of various chemical composition and structure in the oil.
During the development of the oil SAE 5w-30, for the first time, the possibilities of using functional additives of domestic production in its composition were taken into account. At the stage of formulation of the additive package, the synergism of the antioxidant action of the ammonium salt of dialkyldithiophosphoric acid with tetra(2-ethylhexyl) thiuram disulfide obtained by oxidation of di(2-ethylhexyl) was established sodiumdithiocarbamate with an aqueous solution of iodine.
A mixture of these heteroorganic compounds in an equimass ratio is recommended as a new high-temperature primary antioxidant. Additional studies have established a sufficient level of anti-wear properties, as well as the inhibitory effect of this mixture in the reactions of accumulation and decomposition of hydroperoxides.