scholarly journals The Investigation on Rheology and Microstructure for Lithium Complex Grease

2019 ◽  
Vol 2 (2) ◽  
pp. p54
Author(s):  
Mao Jingjing ◽  
Li Jianming ◽  
Qiu Jianwei ◽  
Liu Lijun ◽  
Wang Yue ◽  
...  
Keyword(s):  
Rheological Properties ◽  
Rheological Characteristic ◽  
Damping Factor ◽  
Fiber Structure ◽  
Characteristic Parameters ◽  
Lithium Grease ◽  
Lithium Complex ◽  
Complex Lithium ◽  
Constant Shear Rate ◽  
Transition Index

The rheological characteristic parameters of five lithium complex lubricating greases were determined. The comparison of rheological characteristic parameters and microstructure of the five greases was made. The results showed that the knowledge of the rheological properties of lubricating greases may contribute to reflect the change of the thickener structure. The flow transition index characterized the breaking behavior of inner structure of grease, the greater this index, the better that soap fiber structure of grease; The damping factor was shifted from a medium range towards a lower value which resulted in brittle character of sample. At a constant shear rate, the soap fiber structure of complex lithium grease is dense and uniform, apparent viscosity decline rate is small. In this sense, it is relevant to understand how the development of the soap fiber structures in the grease contributes to several functional and rheological properties of lubricating greases.

Polycarbonate Nanocomposites via Melt Compounding: The Relation between Compatibility and Rheological Properties

2013 ◽  
Vol 739 ◽  
pp. 117-122
Author(s):  
Hojjatollah Sadeghipour ◽  
Farshid Ghorbani ◽  
Mohammad Reza Jafari Felavarjani ◽  
Hassan Ebadi-Dehaghani ◽  
Davoud Ashouri ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Shear Rate ◽  
Rheological Properties ◽  
Cupric Oxide ◽  
Damping Factor ◽  
Cole Plot ◽  
Rotational Mode ◽  
Melt Compounding ◽  
Dynamic Rheological Properties ◽  
Low Shear

The effect of several types of nanoparticles on the rheological properties of polycarbonate (PC) was compared. Four polycarbonate nanocomposites containing 5 wt% of layered silica (SiO2), Iron oxide (Fe3O4), Iron oxide (α-Fe2O3), cupric oxide (CuO) nanoparticles were prepared via melt compounding at 260 °C. Compression molded samples were prepared and the dynamic rheological properties of the nanocomposites were investigated. The incorporation of the nanoparticles increased the storage modulus and consequently decreased the damping factor. In the Cole-Cole plot, PC filled layered silica and Fe2O3 nanoparticles showed more semi-circle pattern comparing to that of other nanocomposites implied more compatibility between PC and layered silica and also Fe2O3 nanofillers. While other nanocomposites showed more deviation from this pattern. Rotational mode in rheological studies showed that at low shear rate the viscosities of nanocomposites are higher than that of pure Polycarbonate. While at higher shear rate the viscosity of filled samples tend to approach the viscosity of pure PC.

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.

Comparison of Several Common Types of Grease Performance Based AR 2000ex Remoter

2014 ◽  
Vol 620 ◽  
pp. 254-262
Author(s):  
Chun Xia He ◽  
Su Zheng Wu ◽  
Hang Song Yang ◽  
Jian Xiu Liu
Keyword(s):  
Rheological Properties ◽  
Work Situation ◽  
Flow Curves ◽  
Lithium Grease ◽  
Impact Performance ◽  
Shear Sensitivity ◽  
Continuous Shear ◽  
The Stability ◽  
The Impact ◽  
Grease Composition

Different substrates grease composition due to differences in their varying degrees of change in viscosity after shearing studied the rheological properties of three different substrates grease. Used AR2000ex rheometer, investigated the effects of different sessions on the rheological properties of the grease. It was found that the stability of lithium grease from the grease either stops working, or their work situation by cutting lubrication properties, are superior to calcium-based grease and urea-based grease. Urea-based grease on the shear sensitivity is smaller relatively than lithium and the recovery of viscosity after being subjected to continuous shear weak, easily lost during use based the grease flow curves with Herschel-Bulkley model, and the impact performance of the grease thixotropic grease is yield stress.

Antioxidant behavior and tribological performance of a novel multifunctional additive in complex lithium grease

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mianran Chao ◽  
Ming Jin ◽  
Peiwei Gong ◽  
Duyi Shen ◽  
Lili Zhu
Keyword(s):  
Tribological Performance ◽  
Friction Reduction ◽  
Esterification Reaction ◽  
Copper Strip ◽  
Multifunctional Additive ◽  
Lithium Grease ◽  
Content Type ◽  
Complex Lithium ◽  
Hindered Phenol ◽  
Ball Test

Purpose This paper aims to contrastively investigate the antioxidant behavior and tribological performance of a novel multifunctional additive (PBT) and dialkyldithiophosphate (ZDDP) in complex lithium grease (CLG). Design/methodology/approach PBT was successfully synthesized through esterification reaction. The antioxidant behavior of PBT and ZDDP was investigated by thermal analysis, and meanwhile, their tribological performance was evaluated by Optimol SRV-IV oscillating reciprocating friction and wear tester (SRV-IV test) and MRS-1J four-ball tester (Four-ball test). Furthermore, their anticorrosion ability was determined by copper strip corrosion test. Findings Four-ball tests showed that the extreme pressure property of PBT was a little inferior to that of ZDDP. Besides, all the other results demonstrated that PBT showed more superior antioxidation stability, friction-reduction and antiwear ability, as well as anticorrosion performance than ZDDP. Originality/value This work provides a study of hindered phenol derivative as a multifunctional additive in lubricant grease, which can contribute to the development of substitution of ZDDP.

Investigation of the Interaction, Rheological and Tribological Properties of Bis(pinacolato)diboron with Lithium Grease During Mechanical Aging

2021 ◽  
Author(s):  
Jia Ren ◽  
Kuiliang Gong ◽  
Gaiqing Zhao ◽  
Xinhu Wu ◽  
Xiaobo Wang
Keyword(s):  
Lewis Acid ◽  
Lewis Base ◽  
Mechanical Degradation ◽  
Fiber Structure ◽  
Acid Base ◽  
Lithium Grease ◽  
Base Complex ◽  
Structure Strength ◽  
Base Grease ◽  
Mechanical Aging

Abstract In this article, Lewis acid–base complex of lithium 12-hydroxystearate (LHS) with diboron compound is formed by the introduction of bis(pinacolato)diboron (B2Pin2) into lithium grease. The interaction between Lewis acid B2Pin2 and Lewis base RCO2− of LHS is characterized by various techniques. Moreover, the rheological and tribological behaviors of the base grease are evaluated at low and moderate temperature, and the results indicate that the addition of B2Pin2 noticeably enhanced the rheological, friction-reducing, and anti-wear (AW) properties of the base grease, which likely owing to the fact that the formation of Lewis acid–base complex is beneficial for improving the soap fiber structure strength, helping to prevent the mechanical degradation of the lithium grease during mechanical aging process.

scholarly journals Binary mixtures of two anionic polysaccharides simulating the rheological properties of oxidised starch

2017 ◽  
Vol 31 (1) ◽  
pp. 117-128
Author(s):  
Marek Sikora ◽  
Anna Dobosz ◽  
Greta Adamczyk ◽  
Magdalena Krystyjan ◽  
Stanisław Kowalski ◽  
...  
Keyword(s):  
Rheological Properties ◽  
Xanthan Gum ◽  
Binary Systems ◽  
Potato Starch ◽  
Hysteresis Loops ◽  
Chemical Reagents ◽  
Structural Recovery ◽  
Anionic Polysaccharides ◽  
Modified Starches ◽  
Constant Shear Rate

Abstract Modifications of starches are carried out to improve their industrial usefulness. However, the consumers prefer natural products. For this reason, various methods of starch properties modification are applied to replace those requiring the use of chemical reagents. The aim of this study was to determine whether it is possible to use binary pastes, containing normal potato starch and xanthan gum, as substitutes of chemically modified starches (with oxidised starch E 1404 pastes as an example). Flow curves with hysteresis loops, apparent viscosity at constant shear rate of 50 s−1 and in-shear structural recovery test with pre-shearing were applied to study the rheological properties of the pastes. It was found that two anionic hydrocolloids, potato starch and xanthan gum, can form binary systems with thickening properties, provided that their proportions are adequately adjusted. Some of the binary pastes under investigation exhibited rheological properties resembling pastes of starch oxidised with hypochlorite (E 1404). The way of tailoring the binary pastes properties is presented.

RELATION BETWEEN SHEAR STRESS AND SHEARING TIME IN SELECTED LUBRICANT COMPOSITIONS

Tribologia ◽  
2018 ◽  
Vol 279 (3) ◽  
pp. 25-33 ◽  
Author(s):  
Ryszard CZARNY
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Rheological Properties ◽  
Tribological Properties ◽  
Shear Stresses ◽  
Test Results ◽  
Molybdenum Disulphide ◽  
Lithium Grease ◽  
Lubricant Composition ◽  
Rate Test

The paper presents the results of studies of the influence of fillers introduced into lubricating greases on changes in values of shear stresses in resulting lubricant compositions. These fillers were powders of graphite, molybdenum disulphide, and PTFE. They are added to grease to improve their tribological properties. They also impact the rheological properties of lubricating compositions, especially on the course of the shear stress, whose value decreases with the duration of the flow of these compositions. Knowledge of changes in the value of this stress is essential in designing central lubrication systems in which these compositions may be used. Tests were performed on lithium grease without fillers as well as on a composition of this grease with the fillers mentioned above. Measurements were carried out using a Rheotest 2.1 rheometer by changing the shearing time at selected gradients of shear rate. Test results have shown that both the kind of filler and the shearing time have an impact on the value of shear stress in the tested lubricant composition.

scholarly journals Investigation on Rheological Properties of Water-Based Novel Ternary Hybrid Nanofluids Using Experimental and Taguchi Method

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 28
Author(s):  
Jalal Mohammed Zayan ◽  
Abdul Khaliq Rasheed ◽  
Akbar John ◽  
Mohammad Khalid ◽  
Ahmad Faris Ismail ◽  
...  
Keyword(s):  
Shear Stress ◽  
Taguchi Method ◽  
Rheological Properties ◽  
Volume Concentration ◽  
Solid Particles ◽  
Hybrid Nanofluid ◽  
Damping Factor ◽  
Water Based ◽  
Hybrid Nanofluids ◽  
The Impact

This study presents the rheological behavior of water-based GO-TiO2-Ag and rGO-TiO2-Ag ternary-hybrid nanofluids. The impact of nanoparticles’ volumetric concentration and temperature on the rheological properties were studied. All experiments were performed under temperatures ranging from 25 to 50 °C in the solid volume concentration range of 0.5–0.00005%. The data optimization technique was adopted using the Taguchi method. The types of nanomaterials, concentration, temperature, and shear rate were chosen to optimize the viscosity and shear stress. The effect of shear stress, angular sweep, frequency sweep, and damping factor ratio is plotted. The experimental results demonstrated that the rheological properties of the ternary hybrid nanofluid depend on the ternary hybrid nanofluid’s temperature. The viscosity of ternary hybrid nanofluids (THNf) change by 40% for GO-TiO2-Ag and 33% for rGO-TiO2-Ag when temperature and shear rates are increased. All the ternary hybrid nanofluids demonstrated non-Newtonian behavior at lower concentrations and higher shear stress, suggesting a potential influence of nanoparticle aggregation on the viscosity. The dynamic viscosity of ternary hybrid nanofluid increased with enhancing solid particles’ volume concentration and temperature.

scholarly journals Rheological Properties of HDPE based Thermoplastic Polymeric Nanocomposite Reinforced with Multidimensional Carbon-based Nanofillers

2021 ◽  
Vol 12 (4) ◽  
pp. 5709-5715
Keyword(s):  
Rheological Properties ◽  
Storage Modulus ◽  
Loss Modulus ◽  
Complex Viscosity ◽  
Damping Factor ◽  
Equal Weight ◽  
Functional Elements ◽  
Weight Percentage ◽  
Potential Applications ◽  
Rheological Test

The present investigation focused on the evaluation of rheological properties HDPE reinforced with equal weight percentage (i.e., 0.1 wt. %) of Nano-diamond (0D), Carbon nanotubes (1D), and Graphite Nano-platelets (2D) multidimensional nanofillers. The results like storage modulus, loss modulus, Tan delta, and complex viscosity results expounded from the rheological test with a frequency sweep from 10-1 to 102 rad/s. The highest storage modulus was perceived by 0.1 CNT-based composites, i.e., 18408 Pa, which decreased to 19, 52, and 85 % for 0.1 GNP, 0.1 ND, and pure, respectively. A similar trend was observed for loss modulus and damping factor results. The shear-thinning behavior observed in viscosity results and the addition of ND nanofillers improve the viscosity to a large amount. The potential applications of the composites include polymer gears, landing mats, cams, and various functional elements.

Sign in / Sign up

Export Citation Format

Share Document