Oil Lubrication Research Articles

Investigation of tribological analysis of safflower oil and 15W40 engine lubrication oil and their blends

In this study, 15W40 engine oil and Safflower oil were blended at 10% (A10), 20% (A20), 50% (A50) ratios. A total of 5 lubrication oil samples were obtained by adding the samples of pure safflower oil (A100) and lubrication oil with no safflower (A0). Viscosity and density tests of A100, A50, A20, A10 and A0 samples were carried out. Wear diameter test was performed on a four-ball testing machine to examine wear and friction properties, and welding load test was performed to examine extreme pressure properties. 
 We also had a study in the safflower oil industry where it can be used as an engine oil additive, especially in internal combustion engines. Since safflower oil is of vegetable origin, its use in engine oils will be environmentally friendly.
 As a result of the examinations, it was determined that as the safflower ratio in the samples increased, the performance increased in terms of viscosity under cold working conditions. When the wear and friction performance was evaluated, it was concluded that there was an improving performance in 15W40 engine oil in A10, A20 and A50 samples in which safflower was used as an additive. When these samples were evaluated in terms of performance, there was little variation between them. For this reason, it is concluded that when Safflower is used as an additive in general, it exhibits positive performance in wear and friction performance. Considering that bio-lubricants are environmentally friendly, it can be said that the A50 sample is the most suitable lubrication oil among the samples, since it contains more vegetable oil than other samples. 
 As a result of this study, it is seen that the use of Safflower oil as an additive in engine oil is a positive result in terms of improving and clean environment.

Sol–gel-assisted synthesis of ultra-fine porous SiO2 nanoparticles for investigation of lubricity and rheological properties of eco-friendly bio-lubricant oil

Sol–gel-assisted synthesis of ultra-fine porous SiO2 nanoparticles for investigation of lubricity and rheological properties of eco-friendly bio-lubricant oil

Effect of applied load on tribological behaviour of Ti–48Al–2Cr–2Nb alloy under oil-lubricated condition

With their low weights and excellent mechanical properties, TiAl alloys are expected to be applied in pistons to achieve energy savings and emissions reductions in internal combustion engines. The tribological behaviours of the Ti–48Al–2Cr–2Nb alloy against the QT600-3 material at different applied loads under oil-lubricated conditions were investigated in this study. The results showed that as the load increased, the friction coefficient and wear-scar volume significantly decreased. The wear surface of the TiAl alloy was analysed using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The wear mechanism of the TiAl alloy under oil lubrication conditions was mainly the combined effect of adhesive wear and oxidation wear, different from the wear mechanism under dry-friction conditions. Furthermore, by observing the cross-sectional morphology of the TiAl alloy after focused ion beam, it was found that the QT600-3 wear debris had compacted and accumulated on the surface of the TiAl alloy, preventing further contact between the TiAl alloy and the QT600-3. This study has the potential to accelerate the application of the Ti–48Al–2Cr–2Nb alloy in lightweight pistons.

Development of Russian lubricants market under sanction pressure

The oil and gas sector is one of the key sectors in the structure of the economy of the Russian Federation, as well as petroleum products industry, and particularly oil lubricants and components for their production. According to official statistics, the share of exports of petroleum products in monetary terms was 29 % in 2021, and in some years the figure was more than 50 %. Because of global events in recent years, including the impact of the COVID-19 pandemic and the consequences of sanction pressure, significant changes have occurred in the global and Russian lubricants markets, which have led to the emergence of turbulence in the markets, and resulted in uncertainty about the further development. The main purpose of this study is to identify the main trends in the development of the lubricants market in Russia in 2023. Within the framework of the study, the concept of “oil lubricants” and the main technological features of their composition and production process are determined. The analysis of the main geopolitical events and changes that occurred in 2022 and their impact on the lubricants market was carried out. In particular, the influence of the latter on the market dynamics of the main raw material component to produce lubricants, as well as its cost both in retrospect and 2023 expectations (taking into account expected consumption volumes in the domestic and foreign markets) was studied. The study gives a brief description of the market segments, as well as analyzes the main brands that were present on the Russian market in 2022 and changes in their composition due to recent events in the industry. Based on the results of investigation, a comprehensive conclusion about the state of Russian lubricants market at the current time and the prospects for its development in 2023 was formulated.

ОХЛАЖДАЮЩИЕ И ТРИБОТЕХНИЧЕСКИЕ ХАРАКТЕРИСТИКИ МАСЛЯНЫХ СОЖ

The paper presents the results of studies aimed at defining the effect of the cooling properties of oil lubricants used in various metalworking processes. The design and a brief description of the installation are given, which allows to obtain temperature-time, temperature-velocity dependencies of various liquids. The use of this installation gives the opportunity to select lubricants according to its cooling properties, depending on the temperature range required by the process. The assessment results of lubricant cooling properties at UZS-2 installation, manufactured according to the requirements of international standards ISO 9950, ASTM D6200 - 01 and ASTM D6482 – 06 are presented. The dependences of tribo-engineering properties of the tested oil lubricants on their cooling characteristics are found out. It is shown that with an increase in the temperature at which the maximum cooling rate of the lubricant is provided, its extreme pressure and anti-wear properties determined according to GOST on a four-ball friction machine increase.

Synthesis of polyelectrolyte-decorated polydopamine nanoparticles via surface reconstruction for enhancing oil-based lubrication

Polydopamine nanoparticles (PDA NPs) show bright prospects in the field of lubricant additives due to their high interface adhesion and reaction properties. However, the synthesis of PDA NPs with excellent dispersibility and lubricity in lubricating oils remains a great challenge. In this work, a class of polyelectrolyte-decorated PDA NPs (PPDA NPs) were synthesized by surface reconstruction of PDA NPs. The lipophilic PPDA NPs can be stabilized in PEG200 base oil without any sediments over 6 months. Compared with PEG200 base oil, the PPDA NPs (1.0 wt%)/PEG200 dispersion not only reduced the friction coefficient (COF) by 37.3 % and wear volume by 51.6 % but also performed well under heavy loads, high speeds, and long duration. Wear surface analyses confirmed that the structural evolution from PPDA NPs to nanosheets induced the formation and deposition of hybrid tribofilm with robust tribological behaviors, enabling desirable oil lubrication. Overall, the synergistic effects between PDA cores and PPDA shells contributed to the superior lubricity of PPDA NPs. This study provides a promising protocol for designing and synthesizing oil-dispersible PPDA NPs, brightening the application prospect of organic polymer NPs in tribology.

A lubrication model for bubbly oil lubrication with interfacial effect and thermal effect using the theory of multiphase mixtures

Bubbly oil lubrication is a type of lubrication method. However, the lubrication model of the bubbly oil has not been thoroughly considered. This paper aims to investigate the modelling for bubbly oil lubrication considering the interfacial effect and thermal effect, and a theoretical model is established based on the theory of multiphase mixtures. The interfacial and thermal effects on the static characteristics of a thrust bearing are analyzed. A test rig for the thrust bearing is developed to measure the static characteristics of the bearing under bubbly oil lubrication. The results show that the bearing static characteristics, i.e. bearing temperature rise, film thickness, friction torque, and volume flow, increase with consideration of three interfacial effects; the bearing temperature rise increases but the film thickness, friction torque, and volume flow rate decrease with consideration of the three thermal effects; the thermal effect on the bearing static characteristics is greater than the interfacial effect.

Tribological responses of steels to different surface films generated in oil lubricants

PurposeThe aim of this study is to experimentally analyze the friction and wear responses of different steels to different surface films generated in oil-lubricated tribological contacts.Design/methodology/approachTribological experiments were conducted using a 100Cr6 bearing ball sliding against a V155 carbon steel disk and 316L stainless steel disk, respectively. Lubricants with additives known to form zinc dialkyl-dithiophosphate (ZDDP) or Ca tribofilms were used.FindingsBoth of the ZDDP and Ca tribofilms helped stabilize the friction coefficient of the carbon steel and stainless steel. The ZDDP tribofilm could effectively protect the carbon steel from wear, in contrast to the stainless steel, whereas the wear of both carbon steel and stainless steel could be significantly reduced by the Ca tribofilm. In the case of neither ZDDP nor Ca tribofilms formation, the 100Cr6 ball was worn by the V155 disk and generated a special surface topography. A polishing wear mechanism was proposed to explain the wear of the 100Cr6 ball.Originality/valueThis study clearly shows the different friction and wear responses of steels to the different surface films and the response is dependent on the tested steel.

A Polytetrafluoroethylene@Polyacrylonitrile core-shell composite with high tribological performance

As a lubricating additive, polytetrafluoroethylene (PTFE) exhibited poor wear resistance, high wear rate and weak adhesion strength, which restricted its application in the area of lubrication and wear protection. In this paper, we prepared a PTFE-based core-shell composite (PTFE@PAN) composed of PTFE core and polyacrylonitrile (PAN) shell through an emulsion polymerization method. The PTFE core with diameter of about 80–100 nm was wrapped by the PAN shell with the thickness of about 50–60 nm. The PTFE@PAN core-shell composite present better dispersion stability in lubricating oil (poly-α-olefin 6, PAO6) than PTFE. Additionally, the PTFE@PAN composite dispersed in PAO6 exhibited significantly reduction in friction coefficient and wear scar width up to 50 % and 25 % compared to PTFE, respectively. Meanwhile, the wear volume of PTFE@PAN composite under a load of 200 N was 4.855 × 104 μm3, was merely one twenty-seventh of that of PTFE (130.6 × 104 μm3). In comparison to conventional oil lubricants, this enhanced tribological properties of PTFE@PAN composite were conducive to a homogeneous transfer film composed of the dual-phase hard polymer (PAN) and soft PTFE polymer (PTFE). Compared with PTFE, the lower surface hardness and better flexibility of PAN shell led to deformation and gap filling with the entanglement and motion of the molecular chains, which could reduce the scratches and decline the abrasive wear of the rubbing surface significantly in the course of the friction process on a rough surface under the high load. That results also suggested that the PTFE@PAN core-shell composite will be a potential lubricating and wear-resistant additive.

Cavitation erosion resistance and tribological performance of PAI/PI/EP soft coating on 20CrMo

A polyamide-imine/polyimide/epoxy resin polymer coating is prepared on the surface of 20CrMo steel by liquid spraying technology which is used to replace the CuPb24Sn copper alloy in valve plates for pumps. Tribological and anti-cavitation erosive experiments of the polymer coating, 20CrMo steel and CuPb24Sn copper alloy are carried out under oil, oil + seawater + silt mixed environment and seawater + silt environment. The results demonstrate that the deposition coating on 20CrMo steel can effectively replace copper alloy for the valve plate of the pump under oil lubrication, oil + seawater + silt environment. Under oil lubrication, the coating exhibits adhesive wear and its average frictional coefficient is 36.63 % and 8.57 % lower than that of the steel and copper alloy, respectively. Likewise, the coating mainly exhibits abrasive wear under the complex working conditions of seawater + silt + oil and seawater + silt. The soft coating reduces the three-body wear and the three-body frictional loss due to the embeddability. Under the complex conditions of seawater + silt + oil, the cavitation mass loss of the coating is 20 % and 35.48 % lower than that of the steel substrate and copper alloy, respectively. In addition, the cavitation mass loss of the coating is 53.6 % and 62.09 % lower than that of the steel and copper alloy under the condition of seawater + silt, respectively. The main influencing factors of the aforementioned results are the lipophilicity of the coating, the large ratio of hardness to elastic modulus (H/E) and the good corrosion resistance.

Effect of Friction Reducers with Unreinforced PEEK and Steel Counterparts in Oil Lubrication

The increasing adoption of PEEK (polyetheretherketone) in many industrial applications has promoted intense research to optimize its lubrication along with the development of friction reducers (FRs), additives that help in reducing fuel consumption and, consequently, CO2 emissions. In this study, the effect of FRs in improving the lubrication of PEEK–steel couplings was evaluated and their mechanism studied using the Mini Traction Machine (MTM) tribometer. Different types of FRs (such as Molybdenum dithiocarbamate, glycerol monooleate, amine and polymeric derivatives) and coupling combinations (steel/steel, steel/PEEK and PEEK/steel) were considered. The oil samples were evaluated as fresh and after a rubbing time considering different operative conditions (from high to low T, fixed load and type of contact motion), and a measurement of the tribofilm was acquired. The experimental campaign showed a ranking among FRs friction-reducing behavior and, in some cases, a synergistic effect was noted between the tribofilm containing the friction modifier and the PEEK surface. Comparing the top performing FRs with reference oil showed a reduction in friction of 22%, 21% and 37%, respectively, in steel–steel, PEEK–steel and steel–PEEK couplings, while in the standard steel–steel coupling, two out of four FRs did not reduce the friction. After conditioning in the presence of PEEK, all friction-modifier additives reduced the friction effectively. This demonstrates the promising performance of PEEK, its compatibility with friction-reducing additives, and its applicability to sliding machine parts in order to improve efficiency and thus reduce CO2 emissions.

Enhancing the Performance of Rapeseed Oil Lubricant for Machinery Component Applications through Hybrid Blends of Nanoadditives

Bio-lubricants have demonstrated promising tribological and physical properties, suggesting their potential advantages in the lubrication of critical machinery components. This study investigates the impact of using blended individual and hybrid nanoadditives, such as graphene nanoplatelets, ZnO, and an ionic liquid (IL) of Trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl)phosphinate, on the rheological, tribological, and physical characteristics of rapeseed oil. A commercial cutting fluid (BLASER Vasco 6000) (VB 6000) is used for comparison. The results revealed a substantial improvement in viscosity index (VI) values for mixtures containing graphene nanoplatelets, reaching up to 150%, as compared to VB 6000. Regarding the tribological behavior, the friction coefficient achieved a reduction of up to 20% at room temperature (RT) and 26% at 60 °C for the hybrid containing all three nanoadditives (H3), outperforming the commercial fluid. Moreover, H3 demonstrated the most substantial reductions in wear volume (84%) and surface roughness (60%). The wettability of H3 benefited from the combined mechanisms of the applied nanoadditives; its application the contact angle decreased by 63%, revealing its outstanding spreadability. The results reveal the high potential of the H3 hybrid as a competitive and green metal working fluid that can replace hostile and toxic ones in industrial applications.

Wear mechanism and evolution of tribofilm of ceramic on steel pairs under ester oil lubrication in wide temperature range

The ceramic-steel-pentaerythritol ester system has a broad application prospect under high temperature conditions, which are respectively in the fields of aviation, aerospace and advanced equipment manufacturing. However, a comprehensive understanding of the friction and wear mechanisms of this system across a broad temperature range remains elusive. The tribological properties of the system at 25–475 °C were studied. With the increase of temperature, the evolution of the tribofilm follows the sequence: discontinuous tribofilm → uniform tribofilm → tribofilm removal. At 200–300 °C, an approximately 100 nm thick amorphous PxOy compound tribofilm is formed, and its nanohardness and modulus are reduced by 81.33 % and 54.02 %, respectively, compared with base steel. The tribofilm effectively reduces shear resistance by blocking friction pair contact. When the temperature exceeds 300 °C, it will lead to high-temperature coking, which adversely affects the lubrication performance. It is worth noting that the system can endure short-term service at a maximum temperature of 475 °C. Therefore, this research can help achieve continuous, stable operation of high-temperature resistant systems, as well as short-term use under extreme conditions encountered by complex equipment.

Effect of Mo Content on Friction and Wear Properties of Fe-Mn-Al-C Alloys Under Different Working Conditions

For this study, Fe-25Mn-9Al-8Cr-1C-xMo alloys (x = 0, 0.1, 0.2, 0.3, 0.4 wt%) were prepared by mechanical alloying combined with vacuum hot-pressing sintering. The corresponding microstructure, mechanical properties, and friction and wear properties under different working conditions (dry friction, oil lubrication and sulfur-containing boundary lubrication) of materials were studied. The results show that the Fe-25Mn-9Al-8Cr-1C alloy is mainly composed of the austenite phase, Cr7C3 phase, and a small amount of a-Al2O3 phase. After adding Mo element, the Fe2MoC phase appears. With the increase of Mo content, the tensile strength and elongation of the alloys increase first and then decrease. In particular, when the Mo content is 0.3 wt%, an excellent combination of strength and toughness is obtained. The product of strength and elongation of the Fe-25Mn-9Al-8Cr-1C-0.3Mo alloy reaches a maximum value of 3.69 GPa·%, which is improved by 158.04% compared with the matrix alloys. With the increase of Mo content, the average friction coefficient and volume wear rate of the alloys show a trend of first decreasing and then increasing under different working conditions. Also, the average friction coefficient and volume wear rate of the alloy with 0.3 wt% Mo reach a minimum value, especially under the condition of sulfur-containing boundary lubrication. The average friction coefficient and volume wear rate of Fe-25Mn-9Al-8Cr-1C-0.3Mo alloy are 0.051 and 0.222 × 10−4 mm3·N−1·m−1, respectively, which are 40.69% and 46.38% lower than those of the matrix alloys.

Tribological Characteristics of Rotary Vane Steering Gear Seals Under the Oil With Different Abrasive Particle Sizes

Abrasive particles often cause wear of the rotary vane seals during an operation process, and lead to seal failure and mechanical fault. Focusing on the wear mechanisms and extracting the tribological information during the friction are the prerequisites for extending the service life and carrying out the fault diagnosis prediction of rotary vane seals. Four different sizes of iron particles were selected to mix with the same volume of hydraulic oil to explore the effect of lubricating oil containing abrasive particles on the wear behaviors of the seal. The tribological behaviors during friction were comprehensively analyzed, including the coefficient of friction (COF), wear volume, surface topography, vibration, noise, and other information. The results demonstrated that the wear characteristics of the seal’s contact surfaces changed obviously. The wear morphologies, coefficients of friction, surface roughnesses, and vibration signals increased with the increase of the abrasive particles’ size, with the wear state gradually worsening. When the iron particle size reached 160 μm, the COF increased by 0.047, and the peak vibration signal increased from 4.31 to 36.97 m/s2, compared with pure hydraulic oil lubrication. This tribological information could disclose the wear mechanisms of thermoplastic polyurethanes (TPU) and reveal the TPU wear states. Determining the tribological information for the rubbing pairs was a potential and effective way for evaluating or predicting the rotary vane steering gear seals’ wear states or failure modes. This study lays the foundation for understanding the wear mechanisms and the fault diagnosis of steering gear seals.

A Review on Oil-Soluble Polyisobutylene-Based Dispersant for Colloidal Stabilization

Oil soluble polymeric-based dispersants have been extensively used in engine oil lubrication formulation due to their inherent properties, such as modifiable viscosity, compatibility, and effectiveness. However, the underlying mechanism of how the dispersant stabilizes soot particles in engine oil is still not fully understood, and discovering this mechanism is crucial for engine oil formulation technology. This review discusses the interactions between colloidal particles induced by two PIBSA-derived dispersants, namely PIBSI and PIBSAE. The effectiveness of these dispersants in stabilizing colloidal particles in oil systems depends on the chemical functional groups present on the main chain. The spectrum of colloidal interactions, ranging from Derjaguin, Landau, Verwey and Overbeek (DLVO) to non-DLVO theory, is predominantly influenced by the equilibrium between dispersant concentration and the overall system viscosity. This phenomenon can eventually reverse colloidal stabilization and result in more serious issues, such as engine wear and tear.

Remarkable lubricity of CNTs microspheres as additives in oil lubricant for ceramic components

Severe wear was often caused by adhesive wear and tribo-chemical reaction for ceramic components. In view of this situation, potentials of carbon nanotubes (CNTs) used as oil additives were explored for lubrication of ceramic/steel tribo-components. Microscopic morphology and dispersion stability of the prepared CNTs were characterized. CNTs microspheres were formed and this might because of their aggregation that also lead to the weak dispersion stability. Additionally, nano-fluids containing various concentration of CNTs microspheres were prepared for exploring the optimum concentration, where their lubricating behavior for ceramic/steel tribo-components was investigated to determine the relation between CNTs microspheres and tribological properties. The results indicated that the optimum concentration was 0.2 wt%, where 53.1 % of friction reduction and 50.7 % of wear resistance were achieved at high contact stress of 1.35 GPa. The superior lubricity of CNTs microspheres might be attributed to their rolling movement and formation of protective film.

Effect of Bi Content on the Microstructure, Mechanical and Tribological Properties of Cu-Sn Alloy.

To reduce the use of the toxic Pb element in the Cu-Sn alloy with high friction performance, Cu-xBi-10Sn alloys with different Bi contents were prepared by gravity casting, and the effect of Bi content on the microstructure, mechanical properties and wear property of Cu-Sn alloys were studied. The results showed that the Bi element was distributed in bands or long strips on the dendritic arms and did not form compounds with other elements. With the increase in Bi content, the hardness and tensile strength of Cu-xBi-10Sn alloys present a trend of increasing first and then decreasing. When the Bi content was 7 wt.%, the maximum hardness value was obtained, and the ultimate tensile strength was close to that of Cu-10Pb-10Sn alloy. Compared with Cu-10Pb-10Sn alloy, Cu-7Bi-10Sn alloy also possessed better friction reduction and wear resistance under the oil lubrication condition.

Influence of Oil Viscosity on the Tribological Behavior of a Laser-Textured Ti6Al4V Alloy.

Laser texturing with a dimple pattern was applied to modify a Ti6Al4V alloy at the micro level, aiming to improve its friction and wear resistance in combination with oil lubrication to optimize the performance in demanding industrial environments. The tribological analysis was performed on four different dimple-textured surfaces with varying dimple size and dimple-to-dimple distance and under lubrication with three different oils, i.e., T9, VG46, and VG100, to reflect the oil viscosity's influence on the friction/wear of the laser-textured Ti6Al4V alloy. The results show that the surfaces with the highest texture density showed the most significant COF reduction of around 10% in a low-viscosity oil (T9). However, in high-viscosity oils (VG46 and VG100), the influence of the laser texturing on the COF was less pronounced. A wear analysis revealed that the laser texturing intensified the abrasive wear, especially on surfaces with a higher texture density. For low-texturing-density surfaces, less wear was observed for low- and medium-viscosity oils (T9 and VG46). For medium-to-high-texturing densities, the high-viscosity oil (VG100) provided the best contact conditions and wear results. Overall, reduced wear, even below the non-texturing case, was observed for sample 50-200 in VG100 lubrication, indicating the combined effect of oil reservoirs and increased oil-film thickness within the dimples due to the high viscosity.

A lubrication model and static characteristics analysis for bubbly oil lubricated journal bearings based on theory of multiphase mixtures

A bubbly oil lubrication model is established in this paper. Interface effect is included in this new model. Two single-component coupled nonlinear generalized Reynolds-type equations are derived based on the theory of multiphase-mixture flow and the second law of thermodynamics. The static characteristics of the finite journal bearings with bubbly oil lubrication are predicted using this theoretical model. The results show that the friction torque is significantly reduced compared to pure oil lubrication at a higher initial bubble volume fraction, and the sidle leakage are significantly increased compared to pure oil lubrication.