Anti-wear Properties Research Articles

Synergistic lubricating behaviors of Zn-MOF/[P88814]DEHP composite used as lubricating oil additive

Use of the synergistic effect between nanomaterials and ionic liquids is of great significance for designing high-performance lubricating materials. In this work, Zn-MOF/[P88814]DEHP (zinc complexes with 2-aminoterephthalic acid nanosheets/trioctyltetradecylphosphonium bis (2-ethylhexyl) phosphate) composites were successfully synthesized by grinding the mixture of [P88814]DEHP and Zn-MOF with different mass ratios and evaluated as a new kind of the white oil additive using a four-ball testing machine. Results demonstrate that the optimal mass ratio of Zn-MOF to [P88814]DEHP was 1:1 and the Zn-MOF/[P88814]DEHP composite with 2.0 wt% addition amount into the white oil significantly reduced friction coefficient and wear. Such obvious friction-reducing and outstanding anti-wear properties of Zn-MOF/[P88814]DEHP composite could be attributed to the synergistic lubrication between Zn-MOF and [P88814]DEHP. This work investigated the synergistic lubrication between MOFs and ILs, which provided a new idea for designing and preparing new lubricating oil additives.

Tribological Properties of Attapulgite Nanofiber as Lubricant Additive for Electric-Brush Plated Ni Coating

In order to expand the application field of attapulgite in tribology, the tribological properties of attapulgite as a lubricant additive on electric-brush plated Ni coating were investigated using the ball-disc contact mode of a SRV-IV friction and wear tester. The worn surfaces were characterized and analyzed via scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). Results indicated that the friction-reducing and antiwear properties of 150 SN lubricating oil on the Ni coating were remarkably improved by an appropriate amount of attapulgite. Tribofilm mainly composed of Ni, NiO, SiO2, Al2O3, graphite, and organic compounds was formed on the worn surface under the action of attapulgite, which was responsible for the reduction of friction and wear.

Tribological Performance of Gd-DLC and Eu-DLC Coatings in the Presence of Synthetic Oils Containing Ionic Liquid Additives

The lubrication of gadolinium-doped diamond-like carbon (Gd-DLC) and europium-doped diamond-like carbon (Eu-DLC) coatings with trihexyltetradecylphosphonium bis(2-ethylhexyl) phosphate ([P66614][DEHP]) ionic liquid (IL) as 1 wt% additive in polyalphaolefin (PAO) 8 was studied. The results of the friction tests under boundary lubrication conditions showed that Gd-DLC and Eu-DLC coatings in the presence of the IL exhibit a friction reduction, especially with the high atomic concentration of doped metal. Later, the surface observation after the long-term wear test indicated that Gd-DLC coatings have less abrasive wear and higher anti-wear properties compared to Eu-DLC coatings due to the enhanced formation of tribofilms derived from the phosphorus of the IL on the steel ball as the counter body. From these results, we have concluded that the friction reduction and the anti-wear property in the presence of the IL can be improved by changing the type and the concentration of the doped metals. This clearly shows that the novel lubrication system combining the Gd-DLC and Eu-DLC coatings with the IL allows for guiding future research and development.Graphical abstract

Tribological Behavior and Wear Protection Ability of Graphene Additives in Synthetic Hydrocarbon Base Stocks

Graphene carbon materials show good tribological properties due to their unique layered structures. In this work, the tribological properties of graphene (GN) and fluorinated graphene (FGN) were studied in two kinds of synthetic hydrocarbon base stocks at different working conditions. Firstly, the structures of GN and FGN were characterized comparatively using FT-IR, Raman, XRD, and TGA. Secondly, the tribological properties of GN and FGN as the lubrication additives both in PAO6 and CTL6 were studied on a four-ball tester. Finally, the surfaces of friction counterparts, before and after tribological tests, were analyzed to disclose the lubrication mechanism using UV, micro-Raman, and EDS. The results show that GN and FGN can be stably dispersed in the selected synthetic hydrocarbon base stocks with 1 wt.% T161 as the dispersant, and the optimal addition of graphene additive is 100 ppm, which shows better friction reducing and anti-wear properties. GN and FGN also show better tribological performance at a higher load (not less than 392 N), and their compatibility with PAO6 is better. The worn surface analysis shows that the graphene additive participates in the lubrication film formation during friction by frictional chemical reaction with friction counterparts, which could improve the stability and tribological performance, resulting in an increased application temperature of synthetic hydrocarbon base stock by at least 10 °C.

ОЦЕНКА АНТИКОРРОЗИОННЫХ, ПРОТИВОИЗНОСНЫХ СВОЙСТВ СОСТАВОВ МАСЕЛ ДЛЯ КОНСЕРВАЦИИ ДВИГАТЕЛЕЙ ЗЕРНОУБОРОЧНЫХ КОМБАЙНОВ

Works on conservation of the internal cavities of internal combustion engines and, first of all, cylinder liners are carried out before placing combine harvesters for off-season storage, for which equipment manufacturers recommend using special conservation technologies and specialized conservation oils. These measures to protect machines from corrosion are practically not used in real operation, primarily because of the high costs of their implementation. A low-cost resource-saving technology for protecting combine harvester engines from corrosion-mechanical wear is being developed at FSBNU VNIITiN by developing a conservation oil composition based on used engine oil. A method for cleaning waste oil from contaminants has been developed. Studies have been carried out to determine the rational composition of the oil, including the use of polymerized rapeseed oil and gun grease as additives that increase anti-wear and anti-corrosion properties. The optimal oil polymerization time has been established to be at least 20 hours, which makes it possible to increase the viscosity of the oil and increase the parameters of the protective film being formed. PVK gun grease is considered as a corrosion inhibitor in the composition of conservation oil. A small amount (3 l) of purified motor oil M-10G2 is taken for mixing PVC with base oil, the mixture is heated to 100°C and mixed for 20 minutes. The resulting enriching mixture of purified oil with dissolved polymerized rapeseed oil and PVC lubricant was added to the main volume of purified oil at a concentration of 3%, 6%, 9%. Based on the studies carried out, the dependences of the change in viscosity were obtained. It has been determined that a 6% additive is a rational concentration for adding an enriching mixture. An assessment of the possibility of precipitation of oil components during their storage showed acceptable values for the thickness of the sediment layer, not exceeding 1 mm. As a first approximation, a new oil composition has been developed, which is easily accessible for production under the conditions of agricultural enterprises of the agroindustrial complex.

Anti-wear (AW) and extreme-pressure (EP) behavior of jojoba oil dispersed with green additive CaCO3 nanoparticles

Lubricating approaches involving nanoparticles have a significant role in reducing friction and wear. Reducing friction is crucial for preserving energy, minimizing emissions, and protecting the environment. The present experimental study investigates green nano-lubricants prepared by dispersing various concentrations of CaCO3 nanoparticles in jojoba oil. The aim of the study is to assess the usability of a bio-sourced alternative nanolubricant to depleting conventional lubricants. The role of nanoparticle concentration and thermo-physical properties in improving the lubrication properties of jojoba oil was thoroughly investigated in the present study. The anti-wear and extreme-pressure behavior of jojoba oil dispersed with CaCO3 nanoparticles were evaluated as per the ASTM D4172 and ASTM D2783 test standards. The coefficient of friction, wear scar diameter, last non-seizure load, initial seizure load, weld point load, and load wear index of each sample were assessed. Compared with pure jojoba oil, the addition of CaCO3 nanoparticles in jojoba oil revealed remarkable anti-wear and extreme-pressure properties with significant improvements in the last non-seizure load, initial seizure load, weld point load, and load wear index, the average friction coefficient and the average wear scar diameter of the steel balls decreased by as much as 34.1% and 40.2%, respectively.

Nano-tribological behavior of CuCoCrFeNi high-entropy alloys at cryogenic temperature: A molecular dynamics study

High-entropy alloys exhibit great potential for cryogenic applications. This study investigates the nano-scratching behavior of CuCoCrFeNi high-entropy alloy at a cryogenic temperature (77 K) using molecular dynamics. Results show that compared with the single-grain model, the average friction coefficient (AFC) increases for all three polycrystalline models with different grain sizes d, but the anti-wear property can be improved by 28.5%, when grain size d = 10.7 nm. The smaller friction on the scratching surface of the single-grain model (AFC is 15.5% less than that of the model with d = 8.2 nm), which makes the overall temperature rise lower compared to that of the polycrystalline models. However, due to the stress concentration released when a complete stacking fault tetrahedron is produced, the single-grain model cannot significantly harden the surface and subsurface to a greater degree. In the polycrystalline models, dislocations are blocked at grain boundaries (GBs). However, the introduction of GBs changes the von Mises stress distribution. Finally, an attempt was made to reveal the role of yield pressure H3/E2 (H—hardness, E—elastic modulus) in friction-reducing and anti-wear properties.

Electrochemical deposition multi-walled carbon nanotube coatings on the surface of Ti6Al4V alloy for enhancing its biotribological properties

Ti6Al4V alloys have potential applications as bone implants. However, their poor biotribological performances affected the service life. In this work, carboxylic multi-walled carbon nanotubes (CMWNT) coatings were grafted on the surface of Ti6Al4V alloys by electrochemical deposition for enhancing the biotribological properties. The CMWNT coatings showed lower coefficient of friction and wear rates, with the reduction of wear rates of 6% in dry condition and 90% under simulated body fluid (SBF) lubrication. This result might be ascribed to the transfer of friction behavior from sliding friction to rolling friction. In addition, the tribological regularity of CMWNT coating with the frequency and load were discussed. Under dry friction, with the increase of frequency and the decrease of normal load, the COF of the CMWNT coating decreased. In SBF lubrication, the COF decreased and the wear rate increased with the increase of frequency. Moreover, the excellent anti-wear properties were observed at the below of 10 N. These findings indicate that the CMWNT coating has an excellent protective effect on titanium alloy, and has a certain application potential in the biomedical field.

Synthesis of Zirconium(IV) Oxyacrylate Complexes with Polypyridine Ligands and Their Application as Precursors of Nanomaterials with Antiwear Properties

Synthesis of Zirconium(IV) Oxyacrylate Complexes with Polypyridine Ligands and Their Application as Precursors of Nanomaterials with Antiwear Properties

Synthesis of Oil Soluble Boron Esters and Obtaining Lubricant Additive Packages with Anti-wear and Extreme Pressure Properties

The purpose of this work is synthesis and characterization of pryridin-yl-borate esters and investigation of tribological performance as additive. The syn-thesis of dialkyl-(2-(pyridin-2-yl) ethyl) borate esters both in the literature and the novel synthesis of dialkyl 2-(methyl (pyridin-2-yl) borate esters and dialkyl 2- (5-ethylpyridin-2-yl) ethyl borate esters were carried out. The boron esters to be obtained were characterized by using IR, 1H NMR,13C NMR spectroscopic methods as well as physical methods such as TAN and corrosion tests. The fric-tion-reducing and anti-wear properties of the synthesized lubricant additives were measured with a four-ball friction and wear tester. As a result of these stud-ies, it has been shown that the friction coefficient is reduced by about 30-40 % compared to the base oil and the wear is also reduced. In the tribological analysis performed using synthesized four molecules within the scope of the study, it was found that resistance to oxidation is increased when the synthesized molecules were added to group I base oil at 0.5 % and 1% w/w concentration. The novel synthesis of dialkyl 2-(methyl (pyridin-2-yl) borate esters and dialkyl 2- (5-ethylpyridin-2-yl) ethyl borate esters were carried out and tribological perfor-mances in base oil were analysed first time.

Study of the Anti-Wear Properties of Motor Oil during Thermostatization

Study of the Anti-Wear Properties of Motor Oil during Thermostatization

TRIBOLOGICAL TESTING OF ENVIRONMENTALLY FRIENDLYLUBRICANTS

This paper compares the properties of mineral oil with glycerol and water-based oil, and rapeseed-based oil.The obtained research results showed that the friction coefficient for mineral oil has similar characteristics forboth loads (25 N/50 N). Minimal differences were also observed for the rapeseed-based oil. However, the mostsignificant difference was obtained for oil based on glycerol and water, where the friction coefficient increasedby more than 23% under the load of 50 N compared to 25 N. The tests showed very good characteristicsof the oils based on rapeseed oil and the oil based on glycerol and water with additives reducing friction,depending on the applied load. For lower loads, the oil based on glycerol and water has very good anti-wearproperties, whereas the oil based on rapeseed oil has very good anti-wear properties for higher loads. Thus,environmentally friendly oils have similar or better lubricating properties under appropriate conditions thantoxic oils with high additive contents. Hence, they have the potential to replace the commonly used mineraloil.

Mechanical and tribological performance of AlCr0.5NbTaxTi4–x (x = 0, 0.5, 1) refractory high-entropy alloys

The tribological behavior of AlCr0.5NbTaxTi4–x (x = 0, 0.5, and 1) refractory high-entropy alloys was systematically investigated from room temperature to 800 °C. The relationship between the alloy composition, microstructure, mechanical properties, and tribological performance was analyzed. The results show that all three alloys have a body-centered cubic (bcc) single-phase structure. The Ta addition enhances solid solution strengthening and increases the melting point that would resist high-temperature thermal softening. As a result, high-temperature strength is enhanced considerably, the coefficients of friction (COF) and wear rates of the alloys are reduced considerably at elevated temperatures, demonstrating excellent friction-reducing and anti-wear properties, e.g., the COF and wear rate of AlCr0.5NbTaTi3 alloy at 800 °C are 0.34 and 4.40 × 10–7 mm3 N–1 m–1, respectively. The excellent wear resistance at high temperatures can be attributed to the formation of an oxide-tribo layer (Ta2O5 and TiO2) with ultrafine-grained layers and good high-temperature mechanical properties.

Application of Nano-Crystalline Diamond in Tribology.

Nano-crystalline diamond has been extensively researched and applied in the fields of tribology, optics, quantum information and biomedicine. In virtue of its hardness, the highest in natural materials, diamond outperforms the other materials in terms of wear resistance. Compared to traditional single-crystalline and poly-crystalline diamonds, nano-crystalline diamond consists of disordered grains and thus possesses good toughness and self-sharpening. These merits render nano-crystalline diamonds to have great potential in tribology. Moreover, the re-nucleation of nano-crystalline diamond during preparation is beneficial to decreasing surface roughness due to its ultrafine grain size. Nano-crystalline diamond coatings can have a friction coefficient as low as single-crystal diamonds. This article briefly introduces the approaches to preparing nano-crystalline diamond materials and summarizes their applications in the field of tribology. Firstly, nano-crystalline diamond powders can be used as additives in both oil- and water-based lubricants to significantly enhance their anti-wear property. Nano-crystalline diamond coatings can also act as self-lubricating films when they are deposited on different substrates, exhibiting excellent performance in friction reduction and wear resistance. In addition, the research works related to the tribological applications of nano-crystalline diamond composites have also been reviewed in this paper.

Synthesis of Multi-butylnaphthalene Base Oils Catalyzed by Trifluoromethanesulfonic Acid and Its Lubricating Properties

Alkylnaphthalene as base oils are widely applied in the production of high-performance lubricating oils. Here, we report the synthesis of multi-butylnaphthalenes by alkylation of naphthalene and n-butene with trifluoromethanesulfonic acid as catalyst. Trifluoromethanesulfonic acid exhibited excellent catalytic performance with naphthalene conversion, as high as 98.5%, and the multi-butylnaphthalenes selectivity of 98.8% under optimum conditions. To investigate the effects of the side-chain numbers on naphthalene on the lubrication performance, two kinds of alkylnaphthalenes were obtained by controlling catalyst dosage, denoted as MBN-1 (90.3% mono/di-butylnaphthalenes) and MBN-2 (98.2% tri/tetra/penta/hexa-butylnaphthalenes), respectively. The primary physiochemical properties of the synthetic oils were tested, and their tribological performance was evaluated. MBN-2, with more side chains on naphthalene, displayed more effective friction reduction and anti-wear properties than MBN-1 and the commercial alkyl naphthalene base oil AN5.

Optimization and wear behaviors of 316L stainless steel laser cladding on rail material

Laser cladding is a potential technology for repairing the rail with side wear. The laser processing parameters should be optimized and the wear behaviors of clads should be analyzed before its application. Therefore, single-pass and multi-pass laser cladding experiments of 316L stainless steel powder with different laser powers, scan speeds, scan modes (directions), and numbers of layers are conducted on the U71Mn rail to optimize the processing parameters. After that, sliding wear tests are conducted on different depths in clad to explore the wear behaviors. The results show that with the increase in laser power, the clad width is increased, the height is increased first and then decreased. With the increase in scan speed, both the clad height and width are decreased. Scan mode 1# produces the thinnest clads, the mode 3 produces the thickest ones. The microstructure of clad is composed of dendritic grains. With the increase in depth in clad, the grain size decreases and the hardness increases. The grain size is increased with laser power and decreased with scan speed, and the hardness is increased with the power and speed. Smallest grains and highest hardness are produced using mode 1#, and largest grains and lowest hardness using mode 3#. The Cr and Ni elements from clad permeate into the heat affected zone of U71Mn rail material. Wear depth of clad has a positive relationship with the grain size and a negative relationship with the post hardness. A wear resistance coefficient, Xphv2.55/Xgs1.56,where Xphv refers to the post hardness and Xgs refers to the grain size, is proposed to characterize the inherent anti-wear property of 316L stainless steel clad on U71Mn rail.

Superior lubricity and corrosion-resistance response of solvated ionic liquids containing lithium and borate

In this work, a method was developed for the in-situ formation of novel solvated ionic liquid containing lithium boron (B-LiIL). Lithium bis (oxalic acid) borate (LiBOB) and lithium bis(mandelate)-borate (LiBMB) were synthesized by in-situ coordinated with polyethylene glycol, which overcame the disadvantages of conventional ILs, such as high expense, serious corrosion, and poor compatibility with base oils. Except for the strength of unique stability, economy, and easily available, these solvated B-LiILs also perform very well in friction-reduction and anti-wear properties on steel/steel contacts even under more demanding test conditions (high temperature and load). Moving on, the solubilization and tribological mechanism are systematically revealed and investigated to rich the design and mechanism exploration of lubricating molecule in this work.

Poly(tannic acid)-functionalized onion-like carbon nanoparticles derived from candle soot serving as potent lubricant additives

Spheroidal onion-like carbon (OLC) nanoparticles exhibit heliocentric graphitic layers are known to possess excellent lubricating properties. Herein, tannic acid (TA) was assembled in-situ onto the onion-like carbon material with Tris (2-aminoethyl) amine (TAEA) to form poly(tannic acid)-functionalized onion-like carbon nanoparticles (P(TA-TAEA)@OLC) via Schiff-base reaction and/or Michael addition. Subsequently, the commercial lubricating additive dialkyl dithiophosphate (DDP) was introduced via Michael addition to bond with the poly(tannic acid) of P(TA-TAEA)@OLC nanoparticles in Tris aqueous solution, to obtain DDP-functionalized onion-like carbon (DDP@OLC) nanoparticles. The as-obtained DDP@OLC nanospheres in the role of lubricating additives demonstrated remarkable friction reduction and wear resistance. With addition of 1 wt % DDP@OLC nanoparticles, the coefficient of friction reduced from 0.17 to 0.10, while the corresponding wear volume loss decreased by 96 %, and the loading capacity reached 600 N from 100 N. The outstanding tribological performance of these as-obtained nanoparticles can be attributable to the formation of a graphitic layer exfoliated from OLC nanoparticles under a high load, and the protective film derived from tribochemical reactions via N, P and S elements of DDP@OLC. Meanwhile, the DDP@OLC nanoparticles can also act as spacers and ball bearings between sliding surfaces, facilitating the enhancement of anti-wear and friction reduction properties.

Viscosity Variations and Tribological Performances of Oleylamine-Modified Fe3O4 Nanoparticles as Mineral Oil Additives

In order to improve the flowabilities and anti-friction and anti-wear properties of lubricants, the viscosity variations and tribological performances of oleylamine-modified Fe3O4 nanoparticles as mineral oil additives were systematically investigated via rotational parallel plate rheometer, ball–disc reciprocating tribometer, non-contact three-dimensional surface profiler, scanning electron microscope, energy dispersive X-ray spectrometer and X-ray photoelectron spectroscopy. Spherical monodisperse Fe3O4 nanoparticles were synthesized and dispersed into mineral oils to obtain lubricants with mass fractions of 1%, 3%, 5%, 8%, 10% and 20%, respectively. These lubricants have excellent stabilities within 12 months. Interestingly, the dynamic viscosity and kinematic viscosity of the lubricants first decrease and then increase with the increase in Fe3O4 content, and the lubricants’ viscosity is at a minimum when the mass concentration is 5%. The tensile curves also show that with the mass fraction increase, the lubricants’ tackiness and adhesion have the same change law, and both reach the lowest point when the mass concentration is 5%. Meanwhile, Fe3O4 nanoparticles can improve the tribological properties of the base oils. It is worth noting that the maximum reduction in the wear volume at 25 °C is up to 93.8% compared with base oils when the additive concentration of the Fe3O4 nanoparticles is 5 wt%.

‘Triangle Ester’ Molecules as Blending Components in Mineral Oil: A Theoretical and Experimental Investigation

The present work explored the use of fatty acid ‘Triangle ester’ molecules (Epoxidized Ester (EE), and Thiirane Ester (TE)) as antifriction and antiwear additives at varying levels for Group I and Group II mineral base oils using the standard ASTMD-4172B four-ball test. Relative to neat base oil, EE blends showed improved antifriction by ~61% and ~42% and antiwear properties by ~32% and ~41% in Group I and Group II base oils, respectively, while the TE blends showed friction reduction by ~65% and ~40% and wear reduction by ~93% and ~50% relative to the same neat base stock. Time evolution of the ‘Triangle ester’ molecules and their blends with mineral oil (modeled as hexadecane) w.r.t. conformational changes, adsorption energy, intermolecular energy, and effect of the applied stress were estimated theoretically using MD simulations. Further, optimized levels of these additives were explored for their effectiveness as a blending component for commercial engine oil (CEO) and could reduce the friction and wear of CEO by ~50% and ~30%, respectively.