Tribological properties of nanometer Al2O3 and nanometer ZnO as additives in lithium-based grease

2018 ◽  
Vol 70 (6) ◽  
pp. 953-960 ◽  
Author(s):  
Qiang He ◽  
Zhigang Wang ◽  
Anling Li ◽  
Yachen Guo ◽  
Songfeng Liu
Keyword(s):  
Tribological Properties ◽  
Wear Scar ◽  
Composite Nanoparticles ◽  
Wear Testing ◽  
Wear Scar Diameter ◽  
Lithium Grease ◽  
Content Type ◽  
Wear And Friction ◽  
Friction Reducing ◽  
Base Grease

Purpose Nanoparticles as the grease additives play an important role in anti-wear and friction-reducing property during the mechanical operation. To improve the lubrication action of grease, the tribological behavior of lithium-based greases with single (nanometer Al2O3 or nanometer ZnO) and composite additives (Al2O3–ZnO nanoparticles) were investigated in this paper. Design/methodology/approach The morphology and microstructure of nanoparticles were characterized by means of transmission electron microscope and X-ray diffraction. Tribological properties of different nanoparticles as additives in lithium-based greases were evaluated using a universal friction and wear testing machine. In addition, the friction coefficient (COF) and wear scar diameter were analyzed. The surface morphology and element overlay of the worn steel surface were analyzed by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS), respectively. Findings The results show that the greases with nanometer Al2O3 or nanometer ZnO and the composite nanoparticles additives both exhibit lower COFs and wear scar diameters than those of base grease. And the grease with Al2O3–ZnO composite nanoparticles possesses much lower COF and shows much better wear resistance than greases with single additives. When the additives contents are 0.4 Wt.% Al2O3 and 0.6 Wt.% ZnO, the composite nanoparticles-based grease exhibits the lowest mean COF (0.04) and wear scar diameter (0.65 mm), which is about 160% and 28% lower than those of base grease, respectively. Originality/value The main innovative thought of this work lies in dealing with the grease using single or composite nanoparticles. And through a serial contrast experiments, the anti-wear and friction-reducing property with different nanoparticles additives in lithium grease are evaluated.

Experimental investigation on the tribological properties of modified carbon nanotubes as the additive in castor oil

2018 ◽  
Vol 70 (3) ◽  
pp. 499-505
Author(s):  
Shanhua Qian ◽  
Hongyue Wang ◽  
Chuanhui Huang ◽  
Yongwu Zhao
Keyword(s):  
Carbon Nanotubes ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
Castor Oil ◽  
Friction And Wear ◽  
Engineering Application ◽  
Wear Scar ◽  
Wear Scar Diameter ◽  
Content Type ◽  
Modified Carbon Nanotubes

Purpose This paper aims to modify carbon nanotubes with oleic acid, and to study the tribological properties of castor oil with modified carbon nanotubes additives. The proper additives are sought for the future engineering application of castor oil. Design/methodology/approach Tribological properties of the castor oils mixed with the modified carbon nanotubes of four mass percentages were investigated using a four-ball testing rig. Coefficient of friction and wear scar diameter were obtained in each test, and the mechanism of modified carbon nanotubes and castor oil was discussed. Findings The results indicated that modified carbon nanotubes had better dispersion in castor oil. Coefficient of friction first increased, then decreased and finally grew stable with the time, and wear scar diameter of steel surface functioned as a first reduced then increased change with the additive mass percentage of modified carbon nanotubes. The minimum of average coefficient of friction and wear scar diameter occurred at 0.02 Wt.% modified carbon nanotubes. Originality/value A small amount of modified carbon nanotubes could improve properties of the castor oil, and the mixed castor oil with 0.02 Wt.% modified carbon nanotubes would be most possibly used in engineering applications.

Quantitative structure tribo-ability relationship of ultra-high molecular weight polyethylene modified by inorganic compounds

2018 ◽  
Vol 70 (1) ◽  
pp. 182-190 ◽  
Author(s):  
Xinlei Gao ◽  
Tingting Wang ◽  
Zhong Cheng
Keyword(s):  
Molecular Weight ◽  
Tribological Properties ◽  
Dry Friction ◽  
Inorganic Compounds ◽  
Quantitative Structure ◽  
Predictive Capability ◽  
Content Type ◽  
Wear And Friction ◽  
Friction Reducing ◽  
Ultra High Molecular Weight

Purpose Ultra-high molecular weight polyethylene (UHMWPE) has an excellent performance and application value; however, as a tribological material, its main drawback is its poor performance under dry friction, impacting its ability to work in high-speed dry friction conditions. Modification of UHMWPE can be carried out to overcome these issues. A significant number of inorganic materials have been used to modify UHMWPE and provide it with good tribological performance. However, thus far, there has been no systematic investigation into the methodology of modifying UHMWPE. The authors take a quantitative approach to determine the structure tribo-ability relationship and basic principles of screening of inorganic compounds suited to modify UHMWPE. Design/methodology/approach The tribological properties of modified UHMWPE using a series of inorganic additives have been qualitatively studied by the authors’ research group previously. In this study, basic quantitative structure tribo-ability relationships (QSTRs) of inorganic additives for modifying UHMWPE were studied to predict tribological properties. A set of 15 inorganic compounds and their tribological data were used to study the predictive capability of QSTR towards inorganic additives properties. Findings The results show that the anti-wear and friction-reducing properties of these inorganic compounds correlate with the calculated parameters of entropy and dipole moment. Increased entropy and smaller dipole moment can effectively improve the anti-wear and friction-reducing ability of inorganic compounds as UHMWPE additives. Additives with larger molecular weight, lower hardness and lower melting and boiling points provide good tribological properties for UHMWPE. For inorganic compounds to act as UHMWPE additives, the chemical bond should be less covalent and have more ionic character. Research limitations/implications Only 15 inorganic compounds and their tribological data were used to study the predictive capability of QSTR towards inorganic additives properties. If the samples number is more than 30, the other QSTR methodology can be used to study the modified UHMWPE, and the models finding can be more precise. Practical implications A QSTR model for modified UHMWPE has been studied systematically. While the results are not more precise and detailed, the model provides a new way to explore the modified UHMWPE characteristics and to reveal new insight into the friction and wear process. Social implications Because the method of studying tribological materials is entirely different from others, the authors want to present the works and discuss it with colleagues. Originality/value The paper presents a new method to study the modified UHMWPE. A QSTR is used to study the tribology capability of compounds from calculated structure descriptors. This study uses the Hartree–Fock ab initio method to establish a QSTR prediction model to estimate the ability of 15 inorganic compounds to act as anti-wear and friction-reducing additives for UHMWPE.

Effect of electromagnetic field on tribological properties of two lubricating oils containing zinc dithiophosphate

2018 ◽  
Vol 70 (5) ◽  
pp. 878-887 ◽  
Author(s):  
Zeqi Jiang ◽  
Jianhua Fang ◽  
Fei Chen ◽  
Boshui Chen ◽  
Kecheng Gu
Keyword(s):  
Electromagnetic Field ◽  
Tribological Properties ◽  
Photoelectron Spectroscopy ◽  
Energy Dispersive Spectrometer ◽  
Content Type ◽  
Lubricating Oils ◽  
Wear And Friction ◽  
Zinc Dithiophosphate ◽  
Friction Reducing ◽  
Worn Surfaces

Purpose This paper aims at understanding tribological properties of lubricating oils doped with zinc dithiophosphate(ZDDP) with and without electromagnetic field impact. Design/methodology/approach The friction and wear properties of the oils formulated with zinc butyloctyl dithiophosphate (T202) or zinc dioctyl dithiophosphate (T203) under electromagnetic field or nonelectromagnetic field were evaluated on a modified four-ball tribotester. The characteristics of the worn surfaces obtained from electromagnetic or nonelectromagnetic field conditions were analyzed by scanning electronic microscopy, energy dispersive spectrometer and X-ray photoelectron spectroscopy. This paper focuses on understanding influence of electromagnetic field on lubrication effect of the ZDDP-formulated oils. Findings The electromagnetic field could effectively facilitate anti-wear and friction-reducing properties of the oils doped with T202 or T203 as compared to those without electromagnetism affection, and the T203-doped oils were more susceptible to the electromagnetic field. The improvement of anti-wear and friction-reducing abilities of the tested oils were mainly attributed to the promoted tribochemical reactions and the modification of the worn surfaces (forming Zn-Fe solid solution) induced by the electromagnetic field. Originality/value This paper has revealed that tribological performances of ZDDP-doped oils could be improved by the electromagnetic field and discussed its lubrication mechanisms. Investigating tribological properties of additives from the viewpoint of electromagnetics is a new attempt, which has significance not only for the choose and designing of additives in electromagnetic condition but also for development of tribological theories and practices.

scholarly journals Tribological Properties of Al2O3 Nanoparticles as Lithium Grease Additives

Lubricants ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 9
Author(s):  
Ahmed Nabhan ◽  
Ahmed Rashed ◽  
Nouby M. Ghazaly ◽  
Jamil Abdo ◽  
M. Danish Haneef
Keyword(s):  
Tribological Properties ◽  
Wear Scar ◽  
Al2o3 Nanoparticles ◽  
Lithium Grease ◽  
Pin On Disc ◽  
Scar Width

The tribological properties of Lithium grease specimens with different concentrations of Al2O3 nanoparticles were investigated using a pin on disc apparatus under different sliding speeds and normal loads. Results showed that Al2O3 nanoparticles enhanced the tribological properties of lithium grease and reduced the COF and wear scar width by approximately 57.9% and 47.5% respectively.

scholarly journals Tribochemistry and EP Activity Assessment of Mo-S Complexes in Lithium-Base Greases

2008 ◽  
Vol 2008 ◽  
pp. 1-6 ◽  
Author(s):  
Tarunendr Singh
Keyword(s):  
Electron Spectroscopy ◽  
Auger Electron ◽  
Wear Scar ◽  
Extreme Pressure ◽  
Flash Temperature ◽  
Wear Scar Diameter ◽  
Activity Assessment ◽  
Temperature Parameter ◽  
Ball Test ◽  
Base Grease

The blends of bis(1,5-diaryl-2,4-dithiomalonamido)dioxomolybdenum(VI) complexes in lithium-base grease are evaluated for their extreme pressure activity in a “four-ball test” using 12.7 mm diameter alloy steel ball specimen. The additive, bis(1,5-di-p-methoxyphenyl-2,4-dithiomalonamido)dioxomolybdenum(VI) and bis(1,5-di-p-chloro-phenyl-2,4-dithiomalonamido)dioxomolybdenum(VI) exhibited lower values of wear-scar diameter at higher load and higher values of weld load, flash temperature parameter, and pressure wear index as compared with lithium-base grease without additives. The greases fortified with the developed additives prevent rusting and corrosion of bearings while grease containing no additives did not pass these tests as per the standard tests. These greases have also better oxidation protection as compared to the grease that has no additive. The topography and tribochemistry of the wear-scar surface are carried out by means of scanning electron microscopy and Auger electron spectroscopy techniques, respectively.

Tribological and rheological properties of nanorods–Al2O3 as additives in grease

2018 ◽  
Vol 233 (4) ◽  
pp. 605-614 ◽  
Author(s):  
He Qiang ◽  
Tao Wang ◽  
Hongwen Qu ◽  
Yong Zhang ◽  
Anling Li ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Rheological Properties ◽  
Steel Surface ◽  
Wear Scar ◽  
Protective Film ◽  
Wear Scar Diameter ◽  
Lithium Grease ◽  
Rheological Behaviors

In this paper, the tribological and rheological behaviors of nanorods–Al2O3 as an additive in lithium grease at different concentrations were investigated. The morphology of the additive was determined. The improvement in the rheological properties after adding the nanorods was studied and illustrated by measuring the wear of the tested surfaces. The results showed that nanorods–Al2O3 can greatly improve the lubricating effect of grease. The grease with a 0.3 wt% content of nanorods–Al2O3 exhibited the lowest average friction coefficient and wear scar diameter. The worn steel surface was smooth and showed few furrows and grooves. Moreover, a correlation was found between the tribological and rheological properties of lithium grease. By increasing the temperature continuously, a chemical protective film was produced leading to the reduction in the friction coefficient of grease.

Preparation and tribological properties of attapulgite – bentonite clay base grease

2014 ◽  
Vol 66 (4) ◽  
pp. 538-544 ◽  
Author(s):  
Tiedan Chen ◽  
Yanqiu Xia ◽  
Zhilu Liu ◽  
Zeyun Wang
Keyword(s):  
Tribological Properties ◽  
Bentonite Clay ◽  
Solid Particles ◽  
Lubricating Grease ◽  
Content Type ◽  
Base Oil ◽  
Dropping Point ◽  
Attapulgite Clay ◽  
Surface Modified ◽  
Base Grease

Purpose – The mixture of attapulgite and bentonite was used as a thickener, and polyalphaolefin was used as the base oil to prepare the new lubricating grease. Some solid particles such as Polytetrafluoroethene (PTFE), MoS2, nano-calcium carbonate and graphite were added in the new lubricating grease as anti-wear additives to investigate the tribological sensitivity. Design/methodology/approach – The new lubricating grease was evaluated by optimol-SRV reciprocating friction and wear tester, and the wear volumes were determined using a MicroXAM-3D. At the same time, the dropping point and the cone penetration were investigated and analyzed. The tribological properties of the new lubricating grease and the sensitivity of some solid lubricating additives to the new lubricating base grease were investigated; pure organic-bentonite and pure organic-attapulgite base grease were used as contrast. Findings – The new lubricating grease based on the surface-modified bentonite/attapulgite clay base grease was synthesized with a relatively high dropping point, and the mass ratio is 25/75 bentonite/attapulgite clay base grease, having a better tribological performance. MoS2 was used as an anti-wear additive that has good tribological sensitivity to the new lubricating base grease. Originality/value – The main innovative thought of this work lies in the mixture of attapulgite and bentonite used as thickener. A relevant report is not available at present.

Effect of MWCNTs/Talc powder nanoparticles on the tribological and thermal conductivity performance of calcium grease

2019 ◽  
Vol 72 (1) ◽  
pp. 9-14 ◽  
Author(s):  
Ahmed Mobasher ◽  
Alaa Khalil ◽  
Medhat Khashaba ◽  
Tarek Osman
Keyword(s):  
Thermal Conductivity ◽  
Tribological Properties ◽  
Power Efficiency ◽  
Friction Reduction ◽  
Wear Testing ◽  
Mechanical Equipment ◽  
Content Type ◽  
Transmission Electron ◽  
Nano Additives ◽  
Pin On Disk

Purpose The purpose of this paper is to evaluate the influence of nanoparticles as an additive on the tribological properties of calcium grease. Design/methodology/approach The nano additives in this research are with different concentration of multi carbon nanotubes (MWCNTs) and Talc powder (1, 2, 3, 3 and 5 per cent). The ratio of MWCNTs to Talc powder is 1:1. The tribological properties of hyper MWCNTs/Talc powder to calcium grease were evaluated using a pin-on-disk wear testing. The results show that the nano additives MWCNTs/Talc to calcium grease exhibit good performance in anti-wear and friction reduction. The action mechanism was estimated through analysis of the worm surface with x-ray diffraction and transmission electron microscope. Findings The result indicates that boundary film mainly composed of MWCNT and Talc powder, and other organic compound was formed on the worm surface during the friction test. In addition, the wear rate and coefficient of friction of nanogreases have shown excellent improvement about 80.62 and 63.44 per cent, respectively, at 4 Wt.% of MWCNTs/Talc powder. Moreover, the thermal conductivity of nanogrease increased about 51.72 per cent. Originality/value This study describes the inexpensive and simple fabrication of nanogrease for improving properties of lubricants, which improve power efficiency and extend lifetimes of mechanical equipment.

3D texture parameters for wear scars after severe regime

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Lorena Deleanu ◽  
Traian Florian Ionescu ◽  
George Catalin Cristea ◽  
Cornel Camil Suciu ◽  
Constantin Georgescu
Keyword(s):  
Rapeseed Oil ◽  
Wear Scar ◽  
Roughness Parameters ◽  
Wear Scar Diameter ◽  
Content Type ◽  
Functional Parameters ◽  
3D Texture ◽  
Texture Parameters ◽  
Practical Implications ◽  
Worn Surfaces

Purpose This paper aims to present an analysis of several 3 D texture parameters for the entire wear scars obtained in severe regime, on a four-ball tester. The aim of this analysis is to correlate the tribological parameter as wear scar diameter to texture parameters. Design/methodology/approach Tested lubricants were rapeseed oil, rapeseed oil additivated with 1% Wt nano TiO2 and rapeseed oil additivated with 1%Wt nano ZnO. The severe regime was applied for 1400 rpm and for loads increasing in steps of 50 N, from 500 to 900 N. Several analyzed roughness parameters (height parameters and functional ones) could be related to the evolution of a wear parameter, the wear scar diameter. Comparing the values for neat rapeseed oil and additivated variants, the texture parameters allow for evaluating if the additives protect or not the worn surfaces. Findings Measurements pointed out two groups of roughness parameters: one that has an evolution depending on wear scar diameter (WSD) and load (Sa, St, functional parameters) and one including Ssk that has shown no dependence on load and WSD. Also, the functional parameters Spk and Svk follow in a similar manner the wear parameter, WSD, but Sk is the least dependent on load. For the highest load, amplitude parameters such as Sa and St are following the tendency of WSD. Each lubricant has its particular correlation between wear parameters and texture quality, expressed by the help of a set of roughness parameters. Research limitations/implications Such studies help tribologists to rank lubricants based on a combined analysis with wear parameters and texture parameters. Practical implications The results allow for evaluating new formulated lubricants. Originality/value The study on the quality on worn surfaces introduces the original idea of analyzing the entire wear scar surface (approximated by an ellipse with the axes as those experimentally measured) by the help of a set of 3 D roughness parameters.

Frictional Performance of an Ionic Liquid/Graphene Composite Additive in Lubricating Oil

NANO ◽  
2021 ◽  
pp. 2150111
Author(s):  
Shengli You ◽  
Ming Zhou ◽  
Mingyue Wang ◽  
Xin Chen ◽  
Long Jin ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Friction Pair ◽  
Testing Machine ◽  
Steel Ball ◽  
Wear Scar ◽  
Wear Testing ◽  
Lubricating Oil ◽  
Wear Scar Diameter ◽  
Base Oil ◽  
Frictional Performance

In this study, we used a four-ball friction and wear testing machine to test the tribological properties of [HPy]BF4 ionic liquids (ILs), low-layer graphene (G), and IL and G compounds (IL/G) as lubricant additives at variousconcentrations, loads, and speeds. The morphology of the wear scar was characterized by a white-light interferometer and a scanning electron microscope (SEM). The results showed that the optimal concentrations of IL and G were 0.10[Formula: see text]wt.% and 0.05[Formula: see text]wt.%, respectively. When the IL concentration was 0.10[Formula: see text]wt.%, the friction coefficient and the wear scar diameter (WSD) reduced by approximately 18% and 8%, respectively, compared to the base oil. When the concentration of G was 0.05[Formula: see text]wt.%, the friction coefficient and WSD reduced by approximately 23% and 12%, respectively, compared to the base oil. After adding the optimal concentration of the IL/G composite additive under the same test conditions, the average friction coefficient of the steel ball reduced by approximately 30%, and the average WSD reduced by approximately 18%. IL/G nanoadditives could be easily attached to the pit area on the friction surface of the steel ball, which made the contact surface of the friction pair smoother and the area of the oil film bearing the load larger, compared to those using the base oil. These two combined phenomena promoted synergistic antifriction and antiwear effects, which significantly improved the frictional performance of the base oil.

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