No abstract

It is shown that in the case of the formation of the heterogeneous structure of the dispersed phase (DP) of greases, which includes the soap component in the form of a complex salt of high molecular weight and low molecular weight acids and nanosized particles of the additive, a more branched structural framework of the DP is formed due to the presence of the additional crystallization centers in the form of the additive nanoparticles. This provides the improved colloidal stability, the greater load capacity and the higher dropping point of the lubricant. The additive nanoparticles implanted into the fibers of the soap component of the DP strengthen it and the probability of their aggregation is excluded. Using as an example the complex lithium grease modified by nanosized particles of the diamond-graphite charge ША-А (ShA-A), it is shown that the formation of the DP heterogeneous structure can improve the rheological and tribological characteristics of the grease in comparison with the lubricant of the same component composition, but having a single DP from the lithium complex and modifying nanoparticles ША-А (ShA-A) that are introduced into the dispersion medium (DM) (oil) separately.

The realization of the synergistic effect is shown on the example of creating of the composite liquid lubricant with improved properties using the combined dispersion medium obtained by mixing of the vegetable and mineral oils. The lubricant for the saw chains and the method of its production are developed. The highly purified mineral oil of group III of the NS-4 brand is added to the rapeseed oil in the amount of 20.0…25.0 wt.%, and the complex of the calcium sulfonate with calcium carbonate in the amount of 1.5…2.0 wt.% is used as a multifunctional additive in the manufacture of this lubricant. The developed lubricant has the following characteristics: kinematic viscosity at 40 °C — 61…63 mm2/s; solidification temperature is –29 °C; flash point — 242…246 °C; welding load — 2,764 N; wear index — 0.39…0.41 mm; mass fraction of free organic acids — 1.3...4.7 mg KOH/g; degree of biodegradability — 88–89 %; warranty period of storage in an open container — 12 months.

It is noted that the development of biodegradable lubricants is an integral part of the development of a modern “green” economy. The distinctive features of the proposed method are described for producing a biodegradable grease on a mixed lithium-calcium thickener, providing for the introduction of alkaline initial components of the dispersed phase (lithium hydroxide monohydrate and calcium hydroxide) into the reaction mass not in the form of their aqueous solutions, but in a powdery state, and the exception of prolonged exposure to water and high temperature on a component of a dispersion medium of plant origin (rapeseed oil) in the process of lubricant synthesis. Along with this, it was proposed to use a highly refined oil of group III according to the API (American Petroleum Institute) standard as a mineral component of the dispersion medium. This provides, in aggregate, the higher stability of the rheological and tribological characteristics of the grease (for at least 12 months) at a given level of biodegradability. The experimental-statistical mathematical model of the process of obtaining the biodegradable lithium-calcium grease is developed, which makes it possible to determine the parameters of the component composition (the content of the mixed lithium-calcium thickener in the grease and the content of lithium stearate in the mixed thickener) and the synthesis modes (the heat treatment temperature of the reaction mass) to achieve the given level of the main characteristics of the finished grease (penetration, dropping point) while ensuring its biodegradability of at least 80 %.

The procedure of working out of the component composition of the biodegradable liquid lubricant for the saw chains is shown. The experimental statistical mathematical model is developed for the optimization of the formulation of the main base taking into account the necessary viscosity and temperature parameters. At the same time the kinematic viscosity of the base body at the temperature of 40 °C and its pure point are chosen as the optimization criteria and the following three factors are used as the optimization parameters: the content of vegetable (rapeseed) oil in the composition, the viscosity of mineral oil at the temperature of 40 °C and the content of an adhesive additive in the base composition. The component composition of the lubricant is adjusted to achieve the required level of tribological properties of the saw chain oil and to ensure the stability of all its characteristics during storage (at least 12 months) and operation at a given level of biodegradability (at least 90 %). In particular, the biodegradable calcium sulfonate grease OIMOL KSC BIO was selected as an additive to improve tribological parameters. The special adhesive additive for vegetable oils of the Petrolad 484BD brand is used to increase the sedimentation stability, and the highly refined oil of group III according to the API standard is recommended to use as a mineral component. The developed lubricant has the following characteristics: density at 15 °C — 926 kg/m3, kinematic viscosity at 40 °C — 47.3 mm2/s, kinematic viscosity at 100 °C — 9.9 mm2/s, viscosity index — 202, pour point — –28 °C, flash point — 272 °C, critical load — 872 N, welding load — 1,600 N, wear index at 200 N — 0.39 mm, biodegradability — 93 %.