Nanodiamonds Particles as Additives in Lubricants

2009 ◽  
Vol 1203 ◽  
Author(s):  
Ivanov G. Michail ◽  
Pavlyshko V. S ◽  
D. M. Ivanov ◽  
Igor Petrov ◽  
Gary McGuire ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Failure Load ◽  
Aggregate Size ◽  
Sharp Decrease ◽  
Colloidal Dispersions ◽  
Test Results ◽  
Extreme Pressure ◽  
Wear Spot ◽  
Pressure Failure ◽  
Ball Test

AbstractIn the current work we report results of tribological testing of stable colloidal dispersions of detonation nanodiamond (DND) and polytetrafluoroethylene (PTFE) in mineral oil based greases as well as in polyalphaolefin (PAO) oil. Testing has been performed on these formula-tions using ring-on-ring, shaft/bushing and four ball test techniques. The test results demon-strated significant improvements for tribological characteristics (friction coefficient, extreme pressure failure load and diameter of wear spot) for certain formulations. A strong synergistic effect when using a combination of DND/PTFE additives was observed by a sharp decrease of friction coefficient. It was also demonstrated that using DND with smaller aggregate size (10nm versus 150nm) resulted in better lubricating performance of PAO-based composition.

An improved nonlinear model considering relative velocity for the friction behavior between untwisted glass-fiber tow and roller

2021 ◽  
pp. 004051752110308
Author(s):  
Yang Liu ◽  
Zhong Xiang ◽  
Xiangqin Zhou ◽  
Zhenyu Wu ◽  
Xudong Hu
Keyword(s):  
Friction Coefficient ◽  
Glass Fiber ◽  
Relative Velocity ◽  
Friction Model ◽  
Woven Fabric ◽  
Test Results ◽  
Application Process ◽  
Friction Behavior ◽  
Improved Model

Friction between the tow and tool surface normally happens during the tow production, fabric weaving, and application process and has an important influence on the quality of the woven fabric. Based on this fact, this paper studied the influence of tension and relative velocity on the three kinds of untwisted-glass-fiber tow-on-roller friction with a Capstan-based test setup. Furthermore, an improved nonlinear friction model taking both tension and velocity into account was proposed. According to statistical test results, firstly, the friction coefficient was found to be positively correlated with tension and relative velocity. Secondly, tension and velocity were complementary on the tow-on-roller friction behavior, with neither being superior to the other. Thirdly, an improved model was found to present well the nonlinear characteristics between friction coefficient and tension and velocity, and predicational results of the model were found to agree well with the observations from Capstan tests.

scholarly journals Comparison Between the Action of Nano-Oxides and Conventional EP Additives in Boundary Lubrication

Lubricants ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 54
Author(s):  
Valdicleide Silva Mello ◽  
Marinalva Ferreira Trajano ◽  
Ana Emilia Diniz Silva Guedes ◽  
Salete Martins Alves
Keyword(s):  
Friction Coefficient ◽  
Boundary Lubrication ◽  
Friction And Wear ◽  
Film Formation ◽  
Environmental Issues ◽  
Protective Film ◽  
Extreme Pressure ◽  
Extreme Pressure Additives ◽  
Environmental Requirements ◽  
Lubrication Conditions

Additives are essential in lubricant development, improving their performance by the formation of a protective film, thus reducing friction and wear. Some such additives are extreme pressure additives. However, due to environmental issues, their use has been questioned because their composition includes sulfur, chlorine, and phosphorus. Nanoparticles have been demonstrated to be a suitable substitute for those additives. This paper aims to make a comparison of the tribological performance of conventional EP additives and oxides nanoparticles (copper and zinc) under boundary lubrication conditions. The additives (nanoparticles, ZDDP, and sulfur) were added to mineral and synthetic oils. The lubricant tribological properties were analyzed in the tribometer HFRR (high frequency reciprocating rig), and during the test, the friction coefficient and percentual of film formation were measured. The wear was analyzed by scanning electron microscopy. The results showed that the conventional EP additives have a good performance owing to their anti-wear and small friction coefficient in both lubricant bases. The oxides nanoparticles, when used as additives, can reduce the friction more effectively than conventional additives, and displayed similar behavior to the extreme pressure additives. Thus, the oxide nanoparticles are more environmentally suitable, and they can replace EP additives adapting the lubricant to current environmental requirements.

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.

scholarly journals Study on Change Rules of Factors Affecting Gas Loss during Coalbed Air Reverse Circulation Sampling

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Demin Chen ◽  
Wei Long ◽  
Yanyan Li ◽  
Rui Zhang
Keyword(s):  
Particle Size ◽  
Sharp Decrease ◽  
Experimental System ◽  
Gas Content ◽  
Impact Factors ◽  
Extreme Pressure ◽  
Factors Affecting ◽  
Reverse Circulation ◽  
Gas Loss ◽  
Skew Distribution

The gas loss in sampling is the root of coalbed gas content measurement error. The pressure and particle size have a significant impact on the gas loss. Using the self-developed coal particle pneumatic pipeline transportation experimental system, this study investigated the pressure and particle size changes in the sampling pipeline. It is found that the sampling process can be divided into four stages: no flow field stage, sample outburst stage, stable conveying stage, and tail purging stage. The extreme pressure in the sampling pipeline appears at the sample outburst stage; and the pressure in the pipeline has levelled off after sharp decrease in the stable conveying stage. It is also found that the extreme pressure increases first and then decreases with the increase of particle size. The duration of outburst stage is negatively correlated with particle size, and that of stable conveying stage is positively correlated with particle size. In addition, the results show that the loss rate of 1–3 mm particles is the smallest after the test but that particles less than 1 mm increase by about two times and particles greater than 3 mm decrease by more than three times. The study also shows that the particle size distribution of coal samples is a single peak with left skew distribution, and the gas reverse circulation sampling test does not change the location of the peak but makes it higher and sharper. The single size coal sample is more likely to collide than the mixture. This study can help to advance the understanding of impact factors on gas loss during reverse circulation sampling.

scholarly journals Prediction Model of Asphalt Content of Asphalt Mixture Based on Dielectric Properties

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Yanhui Zhong ◽  
Yilong Wang ◽  
Bei Zhang ◽  
Xiaolong Li ◽  
Songtao Li ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Prediction Model ◽  
Room Temperature ◽  
Asphalt Mixture ◽  
Aggregate Size ◽  
Asphalt Pavements ◽  
Test Results ◽  
Wide Range ◽  
Asphalt Content ◽  
Ground Penetrating

The rapid detection of asphalt content in asphalt mixture is of great significance to the quality evaluation of asphalt pavement. Based on the dielectric properties of an asphalt mixture, the prediction model of asphalt content is deduced theoretically using three types of dielectric models: Lichtenecker-Rother (L-R) model, Rayleigh model, and Bottcher equation. Under the condition of laboratory mixing at room temperature (about 20–25°C), a dielectric test of asphalt mixture is conducted to verify the applicability of the model. The test results indicate that the dielectric constant of the asphalt mixture is inversely proportional to the asphalt content and directly proportional to the aggregate size of the mixture. Among the models, the Rayleigh model has a wide range of applications and exhibits a high accuracy, with an average relative error of only 1.86%. The results provide a theoretical basis for the nondestructive testing of asphalt pavements using ground-penetrating radar.

Theoretical Assessment of FRP Tendon Wedge Anchorage System

2010 ◽  
Vol 168-170 ◽  
pp. 1006-1009
Author(s):  
Ping Zhuge ◽  
Su Wei Hou ◽  
Shi Zhong Qiang ◽  
Ming Hu Liu
Keyword(s):  
Friction Coefficient ◽  
Carrying Capacity ◽  
Fiber Reinforced Polymer ◽  
Transverse Displacement ◽  
Test Results ◽  
Working Mechanism ◽  
System Effect ◽  
Reinforced Polymer ◽  
Anchorage System ◽  
Theoretical Assessment

In order to improve designing and well understanding the working mechanism for fiber reinforced polymer (FRP) tendon wedge anchorage system (FWAS), a theory for solving the anchorage system was presented in this paper. A designing guidelines of anchorage system was established. The theory was checked by comparing the analytical and test results of a Carbon FRP tendon anchrage system. Effect of presetting load and friction coefficient of sleeve-FRP tendon interface on anchorage performance were evaluated by the theory. The results show that, The theory was proved to be correct, it can be used to predict the carrying capacity of FWAS, and it can calculate the stress and transverse displacement of any point of the anchorage system. The presetting load and friction coefficient of sleeve-FRP tendon interface have great impact to anchorage performance.

The ability of high performance concrete to resist high temperature

2017 ◽  
Vol 8 (4) ◽  
pp. 392-401 ◽  
Author(s):  
Hassan A.M. Mhamoud ◽  
Jia Yanmin
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Mass Loss ◽  
High Performance ◽  
Elevated Temperatures ◽  
High Performance Concrete ◽  
Sharp Decrease ◽  
Test Results ◽  
Content Type ◽  
Chinese Standard

Purpose This study aims to focus on the resistance to elevated temperatures of up to 700ºC of high-performance concrete (HPC) compared to ordinary Portland concrete (OPC) with regards to mass loss and residual compressive and flexural strength. Design/methodology/approach Two mixtures were developed to test. The first mixture, OPC, was used as the control, and the second mixture was HPC. After 28 days under water (per Chinese standard), the samples were tested for compressive strength and residual strength. Findings The test results showed that at elevated temperatures of up to 500ºC, each mixture experienced mass loss. Below this temperature, the strength and the mass loss did not differ greatly. Originality/value When adding a 10 per cent silica fume, 25 per cent fly, 25 per cent slag to HPC, the compressive strength increased by 17 per cent and enhanced the residual compressive strength. A sharp decrease was observed in the residual flexural strength of HPC when compared to OPC after exposure to temperatures of 700ºC.

scholarly journals Mechanical Behavior of a Composite Lightweight Slab, Consisting of a Laminated Wooden Joist and Ecological Mortar

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2575
Author(s):  
Carmelo Muñoz-Ruiperez ◽  
Francisco Fiol Oliván ◽  
Verónica Calderón Carpintero ◽  
Isabel Santamaría-Vicario ◽  
Ángel Rodríguez Sáiz
Keyword(s):  
Laboratory Test ◽  
Mechanical Behavior ◽  
Failure Load ◽  
Full Scale ◽  
Recycled Concrete ◽  
Test Results ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Laboratory Test Results ◽  
Lightweight Mortar

The investigation reported in this paper is an evaluation of the mechanical behavior of full-scale ecological mortar slabs manufactured with a mixture of expanded clay and recycled concrete aggregates. The composite mortars form a compressive layer over laminated wooden joists to form a single construction unit. To do so, full-scale flexural tests are conducted of the composite laminated wood-ecological mortar slabs with different types of mortar designs: reference mortar (MR), lightweight mortar dosed with recycled concrete aggregates (MLC), and lightweight mortar dosed with recycled mixed aggregates (MLM). The test results showed that the mortar forming the compression layer and the laminated wooden joists worked in unison and withstood a higher maximum failure load under flexion than the failure load of the wooden joists in isolation. Moreover, the laboratory test results were compared with the simulated values of the theoretical model, generated in accordance with the technical specifications for structural calculations contained in the Spanish building code, and with the results calculated by a computer software package. From the analysis of the results of the calculation methods and the full-scale laboratory test results, it was concluded that the safety margin yielded by the calculations validated the use of those methods on this type of composite slab. In this way, a strong mixed wood–mortar slab was designed, contributing little dead-load to the building structure and its manufacture with recycled aggregate, also contributes to the circular economy of construction materials.

scholarly journals Experimental Investigation on Flexural Behavior of Granite Stone Slabs with Near Surface Mounted CFRP Bars and Screw-Thread Steels

2018 ◽  
Vol 2018 ◽  
pp. 1-30
Author(s):  
Xiaopeng Gao ◽  
Zhongfan Chen ◽  
Xiaomeng Ding ◽  
Erxiang Dong
Keyword(s):  
Failure Load ◽  
Ductile Failure ◽  
Flexural Behavior ◽  
Screw Thread ◽  
Test Results ◽  
Cracking Behavior ◽  
Near Surface ◽  
Four Point Bending ◽  
Calculation Results ◽  
Near Surface Mounted

An experimental study that investigates the behavior of stone slabs strengthened in fixure with near surface mounted (NSM) technique using screw-thread steels and carbon fiber-reinforced polymer (CFRP) bars is presented. A total of ten full-scale stone slabs were tested under a four-point bending loading to investigate the effect of groove dimension, reinforcement ratios, and reinforcement materials on the flexural performance of stone slabs. The test results included failure characteristics, yield and ultimate capacities, deflection of midspan, and cracking behavior of stone slabs. The test results indicate that with the increase of groove height and groove width, cracking load and middeflection decrease by 6.4%–14.18%; however, failure load and middeflection increase by 4.7%–41.2%. Cracking load, failure load, and failure displacement of stone slabs adopting NSM screw-thread steels increased by 10.9%, 167%, and 617%, respectively, under the maximum reinforcement ratios of 0.629% over the control slab without NSM bars. Meanwhile, with the increase of reinforcement ratios, the failure mode transforms from brittle failure to ductile failure. The calculation results of strength are in agreement with the experimental results. Finally, it can be concluded that NSM CFRP bars are more effective than NSM screw-thread steels to improve flexural capacity with the same reinforcement ratios.

scholarly journals Effect of Polyvinyl Acetate Stabilization on the Swelling-Shrinkage Properties of Expansive Soil

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Jin Liu ◽  
Yong Wang ◽  
Yi Lu ◽  
Qiao Feng ◽  
Faming Zhang ◽  
...  
Keyword(s):  
Laboratory Tests ◽  
Polyvinyl Acetate ◽  
Expansive Soil ◽  
Aggregate Size ◽  
Soil Improvement ◽  
Linear Shrinkage ◽  
Test Results ◽  
Pore Filling ◽  
Sem Images ◽  
Particle Encapsulation

Polyvinyl acetate constitutes a class of polymers that can entirely dissolve in water to form a solution. In this study, polyvinyl acetate as a nontraditional chemical stabilizer was used in soil improvement. Laboratory tests were carried out to evaluate the effect of polyvinyl acetate on swelling-shrinkage properties of expansive soil. A series of shrink/swell tests were performed with adding polyvinyl acetate as amendment at a concentration 3 g/cm3 to four aggregate sizes in the range of 0–0.5 mm, 0.5–1 mm, 1-2 mm, and 2–5 mm and five concentrations 1.5 g/cm3, 3 g/cm3, 4.5 g/cm3, 6 g/cm3, and 9 g/cm3 to soils with aggregate size in the range of 0.5–1 mm for comparison of results with those of untreated soils. The results show that all the linear swelling ratio (LSWR) and linear shrinkage ratio (LSHR) values of the treated specimens decrease. SEM images and the test results indicate the achieved reduction in volume change of the soil tested using soil pore filling and particle encapsulation.

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