Plastic Lubricants Research Articles

EXPERIMENTAL STUDY OF NON-EQUILIBRIUM RHEOLOGICAL EFFECTS DURING THE FLOW OF PARAFFINIC OILS OF TIMAN-PECHORA BASIN. THIXOTROPY, SUPER ANOMALOUS VISCOSITY, OSCILLATIONS OF SHEAR STRESS

Laboratory experiments were carried out to study the non-stationary and non-equilibrium flow regimes of some paraffinic and high paraffinic crude oils of the Timan-Pechora Basin in a rotational viscometer. The presence of thixotropic properties (shear thinnig and hy steresis loops on the flow curves) is shown. The threshold character of the dependence of the area of the hysteresis loop on the oil tempera ture is demonstrated. Experiments have shown that under certain conditions on the flow curves of the studied oils, there are areas of a decrease in shear stress with an increase in shear rate, similar to areas of a «super anomalous» viscosity (SAV) in plastic lubricants. The shape and size of these areas, i.e. the intensity of the «superanomality» manifestation strongly depends on the experiment conditions and are poorly reproducible from experiment to experiment. In experiments, the SAV phenomenon at temperatures below the gelation temperature was always observed when the sample of paraffinic oil was at rest for a sufficiently long time before deformation. If, however, it was in the gap between the viscometer cylinders after the end of the next measurement cycle for a short time (no more than a few minutes), then at the next cycle of recording the flow curve, the SAV phenomenon can be practically imperceptible, although the hysteresis remains. Experiments show that if a sample of high paraffinic oil is deformed at a constant low shear rate, i.e. constant angular velocity of rotation of the device cylinder, and a temperature below the temperature of gelation, then on the falling curve of the dependence of shear stress on time («shear thinning»), oscillations in shear stress with a period equal to the period of rotation of the viscometer cylinder can be observed.

Износостойкость теплостойких сталей ВКС-7 и ВКС-10 после ионно-плазменного азотирования, вакуумной цементации и вакуумной нитроцементации

Tribotechnical characteristics of martensitic grade steels HSM-7 (16Cr2Ni3MoVNbNAl) and HSM-10 (13Cr3Ni3Mo2VNbNAl) were analyzed. Steels underwent ion plasma nitriding, low-pressure carburizing and low-pressure carbonitriding. The concept of a two-stage hardening technology has been implemented: the creation of a thermally stable finely dispersed state of steel at the first stage and the use of such a state for accelerated and qualitative saturation of the surface layer with nitrogen or carbon at the second stage. To create an ultra-finely divided state in the samples of steels under investigation, the method of intensive plastic deformation (IPD) was used. The method is based on the grinding of the microstructure due to large shear deformations. IPD was performed by the method of warm precipitation in a die with a degree of deformation of 80 % at a temperature of 700 ℃. The wear resistance tests of the samples were carried out on a special stand with reciprocating motion in the medium of a plastic lubricant material of mating samples having flat friction surfaces at a pressure of 10 MPa and an average velocity of 0,19 m/s. It is shown that HSM-7 and HSM-10 steels after ion-plasma nitriding and vacuum cementation have high wear resistance (wear intensity I  10-10). After low-pressure carbonitriding, the values of the wear intensity of the friction pair samples are almost the same and amount to 0,3·10-10, which is ~3,0 times less than after low-pressure carburizing. As a result of ion-plasma nitriding and low-pressure carbonitriding, a nanostructured surface layer is formed on steel surfaces contributing to wear resistance increase. The ideas concerning nitrided steel score resistance increase are given.

Development of new C, S, N-containing plastic lubricants based on products from industrial waste integrated processing

The object of this research is the integrated processing of industrial waste from various industries, which makes it possible to reduce the use of material and energy resources and improve the ecological state of the environment. Waste from the chemical, petrochemical, and machine-building industries was subject to integrated technological processing. The common link that united the investigated complex technological cycles was the use of a regenerated mixed sorbent (activated carbon+kieselguhr), on the surface of which topochemical transformations of chemicals that were part of industrial waste took place. Using a regenerated mixed sorbent, exhausted industrial oil which was the mineral basis of the developed new C, S, N-containing plastic lubricants was purified. In particular, we have established the conditions for obtaining diethyl ammonium chloride from unusable pesticides of the formula R1R2R3R4C6HCOOH∙HN(C2H5)2, whose topochemical interaction on the surface of the mixed sorbent leads to the formation of a sorbed fragment [sorbent (activated carbon+kieselguhr)]∙[(C2H5)2NC(=S)SK]. Subsequent interaction of aqueous solutions containing copper(II) ions with such a fragment leads to the formation of bis–(diethyldithiocarbamate)copper(II) on the surface of mixed sorbent. The resulting substances of the general composition [sorbent (activated carbon + kieselguhr)]∙{[(С2H5)2NC(=S)S]2Cu} were studied as thickeners and active polyfunctional components of the obtained plastic lubricants. Research into the tribological properties of new C, S, N-containing plastic lubricants showed their high anti-wear and heat-resistant properties and the possibility of effective use in highly loaded friction nodes

Lubricants

The article indicates that lubricating materials include lubricating oils and lubricants. The majority of lubricating materials are lubricating oils, of which only 8 % are lubricants. Lubricants are divided into solid, gaseous and grease (semisolid). Of the lubricants, greases are the most widely used. In the production of lubricants as a liquid base various mineral, vegetable and synthetic oils were used. Lubricants are preferred over oils. In some cases plastic lubricants can replace lubricating oils. Analysis of scientific, technical and patent literature showed the main directions in the development of lubricants. These include: widely used “Lithium” lubticants, nanosized particles and graphene as additives to lubricants, high-alkaline calcium lubricants, and others. Research and development work related to lubricants is also underway at the Institute of Chemistry of Additives after acad. A.M. Guliyev.

Influence of Silicon Additives on Tribological and Rheological Test Results for Vegetable Lubricants.

This paper describes an investigation of the effects of silicone-containing additives on the tribological and rheological properties of various lubricant blends. Aerosil® and layered silicate were used to modify lubricants containing rapeseed, linseed and soy oil that were thickened with soap thickener. Tribological tests were carried out using a four-ball concentric contact tester. On the basis of the data obtained from the tribological studies of the selected lubricant blends, it was concluded that the addition of amorphous silica increased the anti-seizure and anti-wear properties of the tested lubricants. The addition of montmorillonite caused a significant increase in the values of the individual parameters determining the level of lubricating properties of the tested lubricants in comparison with the lubricants modified with the silica additive. Based on the results of the rheological tests of the studied lubricants, it was found that the applied additives caused a change in the dynamic viscosity and chemical structure of the tested lubricants, expressed by a change in the values of the G' and G″ indices. The main finding of this manuscript was to demonstrate that the use of montmorillonite and aerosil additives improves the functional properties of vegetable-based plastic lubricants. The performance of tribological and rheological tests is of great scientific importance, as it provides an insight into the interaction of siliceous additives with the results of tribological tests on vegetable-oil-based greases. These findings make it possible to determine the behaviour of the lubricant under load and add to the knowledge of vegetable greases.

Influence of Two Types of Few-Layer Graphite Fragments on Viscoelastic Properties of Plastic Lubricants

Influence of Two Types of Few-Layer Graphite Fragments on Viscoelastic Properties of Plastic Lubricants

CFD analysis of hydrodynamic journal bearing with Bingham plastic lubricant considering roughness

CFD analysis of hydrodynamic journal bearing with Bingham plastic lubricant considering roughness

Complex Sorption Treatment of Industrial Waste and Production of Plastic Lubricants

Complex Sorption Treatment of Industrial Waste and Production of Plastic Lubricants

Receiving of New Carbon-Sulfur-Containing Plastic Lubricants Based on Regenerated Products and Used Sorbents

The work is devoted to the solution of the actual problem of waste management and its use for obtaining useful technical products, in particular, special purpose plastic lubricants. The research has been conducted on the use of spent sorbents after complex adsorption purification of industrial wastewater from Cu2+, S2– and HS–-ions in the composition of plastic lubricants. The composition of the latter includes a solid modified surface of sorbents [(activated carbon + kieselguhr) + CuS + S] and regenerated industrial oil I-40A. High operational properties of plastic lubricants are provided by modification of the solid surface of the components, on which there are active centers for chemisorption. The surface modification of activated carbon has been carried out in order to obtain [Cu(µ-S5)]2 or CuS2 as possible equivalent substitutes for MoS2. It was established that the chemical interaction of the pentasulfide anion and the copper (II) cation ends with the formation of a planar six-coordinated chelate center CuS4(Н2О)2 on the surface, followed by its destruction and the formation of copper (II) sulfide and elemental sulfur. Activated carbon acts not only as a sorbent, but also as an active catalyst of topochemical reactions on a solid surface. Modification of the kieselguhr surface is caused by the presence of active centers on its surface – silanol groups –OH, which are subject to esterification. The developed plastic lubricants provide the necessary operational properties of heat-resistant industrial lubricants.

Development of a method for obtaining import-substituting greases based on regenerated synthetic motor oils of Uzbekistan

The purpose of the study is to increase the efficiency of using used engine oils as a dispersion medium for plastic lubricants. It has been established that the removal of resins, carbenes, carbides and asphaltenes from used synthetic motor oils makes it possible to obtain an oil base close to commercial base oils in terms of basic characteristics; refined oils also have a high margin of operational properties. The composition of lubricants for analogues of Lithol-24 and Solid oil-Zh based on refined used engine oils has been determined. Anticorrosive, adhesive and strength properties of lubricant compositions are considered.

Tribological Characteristics of a Plastic Lubricant Based on Grease and a Polyurea Thickener

Tribological Characteristics of a Plastic Lubricant Based on Grease and a Polyurea Thickener

Study of the electrophysical characteristics of plastic lubricants

Actively developing electric automobile transport assumes the creation of conductive lubricants. We pres­ent a setup designed to study the electrophysical properties of industrially produced and model plastic lubricants, as well as the samples of a similar consistency. The setup operates within the current frequency range from 0.1 to 1 kHz and includes a temperature-controlled measuring cell that allows changes in the sample thickness and temperature in the range from 20 to 120 °C. A method for determination of cur­rent-voltage characteristics with subsequent calculation of the specific electrical conductivity is proposed. The specific electrical conductivity of model plastic lubricants based on medical vaseline added with car­bon nanostructures (few-layer graphite fragments and their modified analogs) was studied using the de­veloped setup. Vaseline was used as a base model lubricant, since its rheological properties are similar to that of plastic lubricants and it does not contain any additional additives that can affect the measurement result. The electrically conductive properties of the dispersions of carbon nanostructures and their modi­fied analogs in vaseline were analyzed. It is shown that the introduction of carbon nanostructures into dielectric vaseline turns it into an electrically conductive material. The developed setup makes it possible to study the specific electrical conductivity of systems simulating plastic lubricants with a sufficient accuracy. The results obtained can be used to improve the methodology for studying the specific electrical conductivity of model and industrially produced plastic lubricants, including those with conductive additives.

Rolling resistance coefficient of belt conveyor rollers as function of operating conditions in mines

The article describes the theoretical and experimental studies into the rolling resistance coefficient of rollers of belt conveyors in mines. The experimental testing based on the theory of similarity and dimensions has produced the relationships of the rolling resistance coefficient, the main structural parameters of bearings and the service properties of plastic lubricants at dynamically varied temperature and different belt speeds and roller loads. The reduction in the rolling resistance force applied to the rollers at the adjusted rolling resistance coefficient makes it possible to increase the operating energy efficiency of belt conveyors in mines due to the rational use of modern plastic lubricants.

Оценка антистатических свойств составов, используемых для консервации техники

The most widespread types of conservation compositions (corrosion inhibitor, wax, polish for chromium, and universal plastic lubricant) used to ensure seasonal equipment storage have been analyzed and their antistatic properties have been determined. It was found out that the use only conservation compositions with the best antistatic properties allowed one to achieve the maximum possible service life after deconservation with minimal work and material costs.

Determination of the dynamic hardness of greases as a characteristic of deformation properties in a tribocontact

The efficiency of plastic oil is determined by the duration of its retention on the surface. Evaluation of the effectiveness of plastic lubricants depends on their mechanical properties. It is proposed to use the dependence of hardness on time when pressing a spherical indenter as one of the basic characteristics of the mechanical properties of plastic oils. The method of determining the function of oil hardness is based on the mechanics of contact interaction of a solid ball and a plane presented in this work, which has the property of creep according to the flow theory. One of the main methods of testing the deformation properties of plastic lubricants is to determine the number of penetrations. The number of oil penetrations is determined by the depth of indentation of the indenter; more informative for such a process is the ultimate pressure (hardness), which actually reflects the phenomenon of resistance to indenter indentation in the material. For uniform distribution of pressure under a spherical indenter the technique of construction of function of dynamic hardness of plastic materials is defined and on the basis of tests results of construction of dynamic hardness are received. Tests on contact creep of plastic lubricants are carried out, functions of dynamic hardness are received and the analysis of influence of character of change of dynamic hardness on wear processes in the presence of lubricants is carried out. To analyze the influence of deformation properties on the tribological properties of lubricants, comparative tests of the two above-mentioned types of lubricants on a four-ball friction device were performed. It was found that Litol-24 oil has the best wear resistance. The nonlinear period of running-in for this oil is practically absent that, obviously, under the given conditions of tests is connected with more stable in time deformation properties.

Combined chemical regeneration of industrial waste of various industries

In this paper has been shown the results of the studies on complex sorption purification of industrial waste of various industries with an obtaining new C,S,N-containing plastic lubricants which provide high performance.The conditions for obtaining diethylammonium salt from the obsolete pesticide Banvel D and its sorption on a mixed sorbent, which consist of activated carbon (AC) and kieselguhr (K), have been established. The conditions for obtaining potassium diethyldithiocarbamateon its surface and then, during subsequent treatment with copper(II) sulfate, bis-(diethyldithiocarbamato)copper(II) sorbed on a solid surface, have been examined. Obtainedsorbed substances of general composition [sorbent (AC+ K)]·[(C2H5)2NS(=S)S]2Cu have been studied as active components of plastic lubricants, which provide their high performance.

ПОВЫШЕНИЕ ЭКСПЛУАТАЦИОННЫХ СВОЙСТВ ПЛАСТИЧНЫХ СМАЗОК ГРАФЕНОВЫМИ ДОБАВКАМИ

It is known that commercial lubricants do not always meet high performance requirements in terms of their tribological characteristics. In particular, it was found that at high loads in worn mechanisms, Litol-24 grease does not always provide high anti-wear properties that help extend the service life of plain bearings. In order to improve the performance properties, studies were carried out on the modification of the lubricant with numerous graphenes and comparative tests were carried out on the MI-1M friction machine. The structure of the carbon film was determined by Raman scattering on a DXR Raman Microscope Thermo Scientific spectrometer. As a result of the research, it was found that the modification of the lubricant with graphenes makes it possible to form a film on the friction surface. At the same time, the wear of parts is reduced from 0.0138 mg on the Litol-24 commercial lubricant to 0.0079 on the graphene-modified lubricant. As a result of spectral analysis, it was determined that the spectrum of the carbon film contains approximately the same intensity G-line - 1565 cm-1 and D-line - 1340 cm-1 and a low-intensity 2D line - 2700 cm-1. This spectrum is identical to the Raman spectrum of amorphous carbon. In the spectrum from the metal surface of the roller, the listed lines of the Raman spectrum are absent. In the process of testing on a friction machine of Litol 24 plastic lubricant with multilayer graphene filler, the destruction of the graphene structure and its transformation into amorphous carbon is observed. As a result of determining the roughness of the roller and the thickness of the carbon film with a profilometer, it was found that the surface roughness with a carbon film is less compared to the clean metal surface of the roller: (0.176 - 0.168 = 0.008 μm) and (0.566 - 0.485 = 0.071 μm), the depth of the profile depressions on the surface with carbon film decreased by 0.116 µm. The height of the protrusions of the profile on the surface with the carbon film increased by 0.161 µm. At the same time, it was determined by calculation that the approximate thickness of the carbon film is 0.138 μm. On the basis of the conducted studies, it can be argued that the modification of Litol-24 commercial lubricant with graphenes contributes to the formation of a protective anti-wear film on the friction surface, thereby reducing wear and increasing the service life of machine parts.

Evaluation of tribotechnical properties of plastic lubricants used in heavy loaded bearing units of agricultural machines

The resource of most of the heavily loaded bearing units of agricultural machines in the agro-industrial complex is limited by the quality of the lubricant. To ensure the operating condition of the bearing assemblies, it is necessary to evaluate the tribological characteristics of greases. The paper investigates the lubricity of greases used in agriculture, according to the criterion “scuffing index”. The studies were carried out using standard and original methods for assessing the lubricity of greases. The paper proposes and substantiates a variant of assessing the tribological characteristics of greases based on the “scuffing index” criterion, which consists in determining the wear spot of balls taking into account their plastic deformation zone. It was found that LITOL and LGRT 2 greases have identical antiwear properties.

THE PRODUCTION OF PLASTIC LUBRICANTS BASED ON REGENERATED SYNTHETIC MOTOR OILS USED IN UZBEKISTAN

The purpose of the study is to increase the efficiency of using used engine oils as a dispersion medium for plastic lubricants. It has been established that the removal of resins, carbenes, carbides and asphaltenes from used synthetic motor oils makes it possible to obtain an oil base close to commercial base oils in terms of basic characteristics; refined oils also have a high margin of operational properties. The composition of lubricants for analogues of Lithol-24 and Solidol-Z based on refined used engine oils has been determined. Anticorrosive, adhesive and strength properties of lubricant compositions are considered.

Determination of the coefficient of friction in a screw joint loaded with a controlled torque

The aim of this article is mechanism description for the measuring the friction coefficient in the threads of threaded joint and consecutive experimental measuring of friction coefficient. The coefficient of friction in the threads of a bolt and nut depends on a number of factors, in particular the roughness of the surfaces, the properties of the lubricating film and the angle of the side of the thread. The coefficient is a function of the heat treatment, the quality of the surface protection substance, the size of the screw load and the pitch angle of the thread. The principal parameters of the measuring was fastening torque, which was choose by the torque wrench, axial strength, measured by axial force sensor, and calculated friction coefficient. The friction coefficient was calculated through the use of exponential equation of the torque balance in the screw. The value of the friction coefficient was examined on the threaded joint of size M20 without the plastic lubricants and with the plastic lubricants. Measured values of friction coefficient was close to values listed in the norm and makes argument that plastic lubricants can decrease the friction coefficient in the threads of threaded joint.