scholarly journals Study on Tribological Properties and Mechanisms of Different Morphology WS2 as Lubricant Additives

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1522 ◽  
Author(s):  
Ningning Hu ◽  
Xiuheng Zhang ◽  
Xianghui Wang ◽  
Na Wu ◽  
Songquan Wang
Keyword(s):  
Wear Resistance ◽  
Optimum Condition ◽  
Lubricating Oil ◽  
Stribeck Curve ◽  
Extreme Pressure ◽  
Friction Process ◽  
Wide Range ◽  
The Coefficient Of Friction ◽  
The Relationship ◽  
Better Than

In the present work, the relationship curve of the coefficient of friction (COF) with varying loads of different morphology WS2 lubricating additives in the friction process at various sliding speeds was studied. On this basis, wear marks and elements on the wear surfaces after friction were analyzed, and then the anti-wear and mechanism effects of WS2 of different forms in the lubrication process were discussed. Meanwhile, the Stribeck curve was used to study the lubrication state of the lubricating oil in the friction process. It was revealed that the COF of lubricating oil containing lamellar WS2 decreased by 29.35% at optimum condition and the minimum COF was concentrated at around 100 N. The COF of lubricating oil containing spherical WS2 decreased by 30.24% and the minimum coefficient was concentrated at 120 N. The extreme pressure property of spherical WS2 was better than that of lamellar WS2, and the wear resistance of spherical WS2 was more stable when the load was over 80 N. The different morphology of WS2 additives can play anti-wear and anti-friction roles within a wide range of sliding speeds.

The Wear Behavior of Pulse Current Electroforming Ni-P-SiC Composite Coatings

2007 ◽  
Vol 364-366 ◽  
pp. 358-363 ◽  
Author(s):  
Kung Hsu Hou ◽  
Ming Chang Jeng ◽  
Yung Kang Shen ◽  
Ming Der Ger
Keyword(s):  
Weight Loss ◽  
Wear Resistance ◽  
Pulse Current ◽  
Wear Behavior ◽  
Composite Coatings ◽  
Wear Weight Loss ◽  
Sic Particles ◽  
The Coefficient Of Friction ◽  
Worn Surface ◽  
The Relationship

In this study, the SiC particles with a mean diameter of 300nm were used to be codeposited with Ni-P base to produce Ni-P-SiC composite coatings by means of the pulse current electroforming technology. The relationship between the SiC particles and phosphorous contents in the composite coatings has been constructed. The wear behavior of the Ni-P-SiC composite coatings was examined by that measurements data including the wear weight loss, the coefficient of friction, and the temperature increments under the wear tests, in which were correlated to the observation and analysis of the worn surface of the composite coatings. Experimental results show that the wear resistance of Ni-P-SiC composite coatings is superior to Ni-P composite coatings, if they are under the same level of hardness. In addition, the wear weight loss of Ni-P-SiC composite coatings is even about 62% less than that of Ni-P composite coatings, if they are based on the same production conditions. Further more, both the hardness and wear resistance of Ni-P-SiC composite coatings are superior to pure Ni coating, wherein its wear resistance is even up to 10 times better than that of pure Ni coating.

scholarly journals Evolution of bacterial transformation: is sex with dead cells ever better than no sex at all?

Genetics ◽  
1988 ◽  
Vol 119 (1) ◽  
pp. 213-221
Author(s):  
R J Redfield
Keyword(s):  
Deleterious Mutation ◽  
Fitness Function ◽  
Bacterial Transformation ◽  
Wide Range ◽  
Mean Fitness ◽  
The Mean ◽  
Transforming Cell ◽  
Asexual Populations ◽  
The Relationship ◽  
Better Than

Abstract Computer simulations of bacterial transformation are used to show that, under a wide range of biologically reasonable assumptions, transforming populations undergoing deleterious mutation and selection have a higher mean fitness at equilibrium than asexual populations. The source of transforming DNA, the amount of DNA taken up by each transforming cell, and the relationship between number of mutations and cell viability (the fitness function) are important factors. When the DNA source is living cells, transformation resembles meiotic sex. When the DNA source is cells killed by selection against mutations, transformation increases the average number of mutations per genome but can nevertheless increase the mean fitness of the population at equilibrium. In a model of regulated transformation, in which the most fit cells of a transforming population do not transform, transforming populations are always fitter at equilibrium than asexual populations. These results show that transformation can reduce mutation load.

Study of behaviour of aluminium oxide nanoparticles suspended in SAE20W40 oil under extreme pressure lubrication

2015 ◽  
Vol 67 (4) ◽  
pp. 328-335 ◽  
Author(s):  
Avinash A. Thakre ◽  
Animesh Thakur
Keyword(s):  
Coefficient Of Friction ◽  
Normal Load ◽  
Friction Reduction ◽  
Lubricating Oil ◽  
Extreme Pressure ◽  
Sliding Speed ◽  
Content Type ◽  
Base Oil ◽  
Pin On Disc ◽  
The Coefficient Of Friction

Purpose – The purpose of this paper is to include investigation on extreme pressure lubrication behaviour of Al2O3 nanoparticles suspended in SAE20W40 lubricating oil. Effects of nanoparticles size (40-80 nm) and its concentration (0-1 per cent) on the coefficient of friction is studied using pin-on-disc tribotester. Design/methodology/approach – Taguchi technique is used to optimize the process parameters for lower coefficient of friction. L18 orthogonal array involving six levels for one factor and three levels for remaining three factors is selected for the experimentation. The parameters selected for the study are sliding speed, normal load, nanoparticles size and its concentration in base oil. Findings – It has been found that the presence of nanoparticles in proper concentration shows excellent tribological improvement in frictional characteristics compared to the base oil. The optimal combination of the parameters for minimum coefficient of friction is found to be 0.8 per cent concentration of 60 nm sized Al2O3 nanoparticles, 1,200 rpm sliding speed and 160 N of normal load. The mechanism of friction reduction in presence of nanoparticles is investigated using scanning electron microscopy. Originality/value – This is the original work.

Effective Tribology Testing of Lubricating Oils

2005 ◽  
Author(s):  
Norm Gitis
Keyword(s):  
Friction And Wear ◽  
Normal Load ◽  
Stribeck Curve ◽  
Unified Approach ◽  
Contact Electrical Resistance ◽  
Wide Range ◽  
The Coefficient Of Friction ◽  
Comprehensive Characterization

There are several solutions suggested to develop the unified approach to tribological testing of oils. For evaluation of the coefficient of friction and wear, it is suggested to monitor friction force, normal load, and in-situ wear dynamics, as well as to clearly distinguish the running-in and stable-wear components. Tests on lab-bench testers are recommended to start from obtaining a Stribeck curve in a wide range of loads and speeds. During the tests, monitoring additional parameters of contact acoustic emission and contact electrical resistance is beneficial for sensitive and comprehensive characterization of oils and greases.

scholarly journals Stribeck Curve of Magnetorheological Fluid within Pin-on-Disc Configuration: An Experimental Investigation

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4670
Author(s):  
Jakub Roupec ◽  
Filip Jeniš ◽  
Zbyněk Strecker ◽  
Michal Kubík ◽  
Ondřej Macháček
Keyword(s):  
Coefficient Of Friction ◽  
Magnetorheological Fluid ◽  
Liquid Hydrocarbon ◽  
Stribeck Curve ◽  
Mr Fluid ◽  
Carrier Fluid ◽  
Lubrication Regimes ◽  
Wide Range ◽  
The Coefficient Of Friction ◽  
Disc Configuration

The paper focuses on the coefficient of friction (COF) of a magnetorheological fluid (MRF) in the wide range of working conditions across all the lubrication regimes—boundary, mixed, elastohydrodynamic (EHD), and hydrodynamic (HD) lubrication, specifically focused on the common working area of MR damper. The coefficient of friction was measured for MR fluids from Lord company with concentrations of 22, 32, and 40 vol. % of iron particles at temperatures 40 and 80 °C. The results were compared with a reference fluid, a synthetic liquid hydrocarbon PAO4 used as a carrier fluid of MRF. The results show that at boundary regime and temperature 40 °C all the fluids exhibit similar COF of 0.11–0.13. Differences can be found in the EHD regime, where the MR fluid COF is significantly higher (0.08) in comparison with PAO4 (0.04). The COF of MR fluid in the HD regime rose very steeply in comparison with PAO4. The effect of particle concentration is significant in the HD regime.

Application of TEM to Deformation, Wear, and Fracture of Ceramics

1974 ◽  
Vol 32 ◽  
pp. 472-473
Author(s):  
B. J. Hockey
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Brittle Materials ◽  
High Temperature Strength ◽  
Wide Range ◽  
Corrosive Environments ◽  
Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

The Problem of Identifying and Modeling the Relationship between Monetary Factor and Inflation in the Russian Economy

2008 ◽  
pp. 61-76
Author(s):  
A. Porshakov ◽  
A. Ponomarenko
Keyword(s):  
Money Supply ◽  
Money Demand ◽  
Russian Economy ◽  
Long Run ◽  
Complex Approach ◽  
Wide Range ◽  
Long Time ◽  
The Relationship ◽  
Supply Side Factors

The role of monetary factor in generating inflationary processes in Russia has stimulated various debates in social and scientific circles for a relatively long time. The authors show that identification of the specificity of relationship between money and inflation requires a complex approach based on statistical modeling and involving a wide range of indicators relevant for the price changes in the economy. As a result a model of inflation for Russia implying the decomposition of inflation dynamics into demand-side and supply-side factors is suggested. The main conclusion drawn is that during the recent years the volume of inflationary pressures in the Russian economy has been determined by the deviation of money supply from money demand, rather than by money supply alone. At the same time, monetary factor has a long-run spread over time impact on inflation.

DURCOMET 100

Alloy Digest ◽  
1993 ◽  
Vol 42 (2) ◽  
Keyword(s):  
Fracture Toughness ◽  
Wear Resistance ◽  
Corrosion Resistance ◽  
Mechanical Strength ◽  
Heat Treating ◽  
Corrosion And Wear ◽  
Annealed Condition ◽  
Excellent Corrosion Resistance ◽  
Wide Range ◽  
Very High

Abstract Durcomet 100 is an improved version of Alloy CD-4 MCu with better corrosion and wear resistance. The alloy is used in the annealed condition and possesses excellent corrosion resistance over a wide range of corrosion environments. Mechanical strength is also very high. This datasheet provides information on composition, physical properties, hardness, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as heat treating and joining. Filing Code: SS-540. Producer or source: Duriron Company Inc.

CRUCIBLE CPM S30V

Alloy Digest ◽  
2003 ◽  
Vol 52 (9) ◽  
Keyword(s):  
Fracture Toughness ◽  
Stainless Steel ◽  
Wear Resistance ◽  
Corrosion Resistance ◽  
Physical Properties ◽  
Martensitic Stainless Steel ◽  
Heat Treating ◽  
Corrosion And Wear ◽  
Better Than

Abstract Crucible CPM S30V is a martensitic stainless steel designed with a combination of toughness, wear resistance, and corrosion resistance equal to or better than 440C. This datasheet provides information on composition, physical properties, microstructure, hardness, and elasticity as well as fracture toughness. It also includes information on corrosion and wear resistance as well as heat treating and machining. Filing Code: SS-891. Producer or source: Crucible Service Centers.

Research of the activity and viability of spermatozoa at different concentrations and proportions of diluents after incubation

2020 ◽  
pp. 88-95
Author(s):  
Svitlana Lobchenko ◽  
Tetiana Husar ◽  
Viktor Lobchenko
Keyword(s):  
Plasma Concentration ◽  
Incubation Time ◽  
Coefficient Of Variation ◽  
Incubation Medium ◽  
Wide Range ◽  
Series Of Experiments ◽  
The Subject ◽  
Boar Spermatozoa ◽  
Native Plasma ◽  
Better Than

The results of studies of the viability of spermatozoa with different incubation time at different concentrations and using different diluents are highlighted in the article. (Un) concentrated spermatozoa were diluented: 1) with their native plasma; 2) medium 199; 3) a mixture of equal volumes of plasma and medium 199. The experiment was designed to generate experimental samples with spermatozoa concentrations prepared according to the method, namely: 0.2; 0.1; 0.05; 0.025 billion / ml. The sperm was evaluated after 2, 4, 6 and 8 hours. The perspective of such a study is significant and makes it possible to research various aspects of the subject in a wide range. In this regard, a series of experiments were conducted in this area. The data obtained are statistically processed and allow us to highlight the results that relate to each stage of the study. In particular, in this article it was found out some regularities between the viability of sperm, the type of diluent and the rate of rarefaction, as evidenced by the data presented in the tables. As a result of sperm incubation, the viability of spermatozoa remains at least the highest trend when sperm are diluted to a concentration of 0.1 billion / ml, regardless of the type of diluent used. To maintain the viability of sperm using this concentration of medium 199 is not better than its native plasma, and its mixture with an equal volume of plasma through any length of time incubation of such sperm. Most often it is at this concentration of sperm that their viability is characterized by the lowest coefficient of variation, regardless of the type of diluent used, which may indicate the greatest stability of the result under these conditions. The viability of spermatozoa with a concentration of 0.1 billion / ml is statistically significantly reduced only after 6 or even 8 hours of incubation. If the sperm are incubated for only 2 hours, regardless of the type of diluent used, the sperm concentrations tested do not affect the viability of the sperm. Key words: boar, spermatozoa, sperm plasma, concentration, incubation, medium 199, activity, viability, rarefaction.

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