THE AGING PROCESS OF MOTOR OILS DURING OPERATION

Аннотация

During the aging process, the composition of the oil becomes more complicated due to the accumulation of impurities in it, thermal or thermo-chemical decomposition of hydrocarbons and additives. These products enter into physical and chemical interactions with each other and with pollutants. There is also evaporation of light fractions of oil, the activation of additives, contamination with various mechanical impurities, water. To ensure minimal wear of engine parts, we suggest using oils of higher viscosity for hot climatic conditions. KEYWORDS: Oil aging, high temperature, oxidizing environment, engine oils, deposits, viscosity, loads in the friction unit, oil film, carbon deposits. INTRODUCTION environment, external contaminants, catalysts (wear products of metal surfaces) and other The working oil continuously changes under factors. A set of processes accompanied by a the influence of high temperature, oxidizing change in the composition and properties of “THE AGING PROCESS OF MOTOR OILS DURING OPERATION” P age 166 | 4 the working oil in an unfavorable direction is enter into physical and chemical interactions called oil aging. with each other and with pollutants coming from outside. It is not possible to study in The aging of the oil occurs due to its detail and trace all the diversity and multi- contamination by atmospheric dust, wear stage transformations of all the components products, gas formation, liquid and solid of the starting oil. Therefore, usually the whole particles formed during the combustion of set of aging processes of diesel oils operating fuel, as well as a result of chemical and in diesel lubrication systems is conditionally physico-chemical changes in the hydrocarbons divided into several main integrally evaluated of the base oil and the components of processes. additives introduced into these oils. Oil aging (which in turn leads to the formation of high- These include: and low-temperature deposits on engine - oxidation; parts) can cause: - evaporation; - coking of piston rings, their burning and complete loss of mobility (jamming in the - thermal or thermo-oxidative decomposition piston grooves) of hydrocarbons that form the basis of the oil; - temperature increase due to deterioration of - contamination by fuel and oil combustion the heat sink products, dust, wear products; - jamming of valves in guide bushings - consumption of additives or depletion of their action due to the neutralization of - burnout of valves inorganic acids, thermal decomposition, - reduction of the passage section of the intake entrainment from the working oil into deposits and exhaust tracts on oil filters, chemical reactions of interaction with oxidation products of oil and fuel, etc.; - contamination of the walls of the oil receivers of pumps, filters and oil channels of the - watering of oil as a result of condensation of lubrication system, drainage holes in the oil water and gases breaking into the crankcase, rings and the piston or violation of the tightness of the cooling system; - increase in oil viscosity and corrosion wear of cylinder-piston group parts - dilution of oil by fuel due to malfunctions of the high-pressure fuel pump, injectors, - increased corrosion of bearing alloys and violation of the tightness of the fuel supply iron-containing parts system or prolonged idle operation. - abrasive wear of parts by solid particles of The chemical composition of oils and their contaminants. operational properties change dramatically During the aging process, the composition of during operation — under the influence of the oil becomes more complicated due to the high temperatures, air oxygen, products of accumulation of impurities in it coming from incomplete combustion of fuel, condensing the outside, as well as oxidation products of water, crankcase gases, catalytic action of thermal or thermo-chemical decomposition of metals and old oxidation products. hydrocarbons and additives. These products “THE AGING PROCESS OF MOTOR OILS DURING OPERATION” P age 167 | 4 In addition, evaporation of light oil fractions surfaces such as pistons and piston rings), occurs, additives are triggered, contamination low—temperature deposits - sludge, corrosion with various mechanical impurities, water. and destruction of metals, for example, bearing liners formed by acidic products. The oil's resistance to oxidation by oxygen in the air (chemical stability) is one of the most To ensure minimal wear of engine parts, it is important factors determining the behavior of better to use oils of higher viscosity. However, oil in friction units during operation, as well as such an increase in viscosity, especially for its service life before replacement. Oxidation engines that are not heated to operating leads to the formation of varnish and temperature, causes starting wear and carbonaceous deposits (especially on hot deterioration of fuel and economic indicators. Defective indicators of working oils Values of oil indicators