scholarly journals Analysis of surface structure of zirconia crystals in case of friction against steel

2020 ◽  
Vol 329 ◽  
pp. 02008
Author(s):  
Valery Alisin ◽  
Mikhail Borik ◽  
Alexey Kulebyakin ◽  
Elena Lomonova ◽  
Irina Suvorova
Keyword(s):  
Dry Friction ◽  
Friction Surface ◽  
Friction Pair ◽  
Base Material ◽  
Electron Microscopic Examination ◽  
Third Body ◽  
Electron Microscopic ◽  
The Third ◽  
Transfer Films ◽  
Friction Surfaces

The article considers the formation of the third body during dry friction of the nanostructured zirconia crystals partially stabilized with yttria against steel. The assumption is substantiated that the tribological properties of the studied friction pair are determined by the properties of the films formed on the surface of the crystals. Friction tests under sliding conditions were performed according to the “disk-finger” scheme. The results of electron microscopic examination of the friction surfaces of crystals are presented. The elemental composition was determined, and the phase composition of the transfer films of various sections of the crystal friction surface was calculated. At high magnifications, it was found that the friction surface of samples with 2-4 mol.% of Y2O3 has the sufficiently homogeneous structure of the films with traces of boundaries of smaller particles of the transferred material. Destruction of the friction surface of a sample with a Y2O3 content of 8 mol.% occurs at a deeper level and affects not only the layer of secondary structures, but also the underlying layers of the base material.

scholarly journals STRUCTURE AND DEVELOPMENT OF VIRUSES AS OBSERVED IN THE ELECTRON MICROSCOPE

1962 ◽  
Vol 116 (4) ◽  
pp. 553-564 ◽  
Author(s):  
Councilman Morgan ◽  
Konrad C. Hsu ◽  
Harry M. Rose
Keyword(s):  
Influenza Virus ◽  
Viral Antigen ◽  
Electron Microscopic Examination ◽  
Serial Passage ◽  
Electron Microscopic ◽  
The Third ◽  
Magnus Effect ◽  
Viral Particles ◽  
Membrane Bound ◽  
Cytoplasmic Processes

Chicken embryos were infected by the chorioallantoic route with influenza virus, PR8 strain, in the form of undiluted chorioallantoic fluid. Electron microscopic examination 24 hours after infection revealed that membrane-bound fragments of cytoplasm appeared to be in process of release from entodermal cells of the chorioallantois. The number of such fragments was greatly increased in proportion to the number of typical viral particles after the third serial passage, which was accompanied by a reduction of the infectivity-hemagglutinin ratio (von Magnus effect). The lack of recognizable internal components, together with the presence of surface structure which closely resembled that of the virus and frequently contained viral antigen, suggested that many of these fragments were incomplete viral particles. It is proposed that concentrated inocula damage the cells and interfere with differentiation of the virus, but do not inhibit formation and detachment of cytoplasmic processes. Under these circumstances the accumulation of viral antigen at the surface of the cell will result in the predominant formation of incomplete virus.

Friction Coefficient as a Macroscopic View of Local Dissipation

2007 ◽  
Vol 129 (4) ◽  
pp. 829-835 ◽  
Author(s):  
D. Richard ◽  
I. Iordanoff ◽  
Y. Berthier ◽  
M. Renouf ◽  
N. Fillot
Keyword(s):  
Friction Coefficient ◽  
Dry Friction ◽  
Three Dimensional ◽  
Third Body ◽  
The Third ◽  
Dynamic Friction Coefficient ◽  
Approaches To Study ◽  
Set Up ◽  
Method Approach ◽  
Simple Interaction

This paper presents an overview of a discrete element method approach to dry friction in the presence of a third body. Three dimensional computer simulations have been carried out to show the influence of the third body properties (and more specifically their adhesion) on friction coefficient and profiles of dissipated power. Simple interaction laws and a cohesive contact are set up to uncouple the key parameters governing the contact rheology. The model is validated through a global energy balance. As it is shown that dynamic friction coefficient can be explained only in terms of local energy dissipation, this work also emphasizes the fact that mechanism effects and third body rheology have important consequences on the energy generation and dissipation field. Therefore, asymmetries can arise and the surface temperature of first bodies can be significantly different even for the same global friction coefficient value. Such investigations highlight the fact that friction coefficient cannot be considered in the same way at the mechanism scale as at the contact scale where the third body plays a non-negligible role, although it has been neglected for years in thermal approaches to study of surfaces in contact.

Engagement of Oil Immersed Multi-Disc Clutches

1992 ◽  
Author(s):  
Bengt Jacobson
Keyword(s):  
Simple Model ◽  
Dry Friction ◽  
Friction Surface ◽  
Friction Torque ◽  
Oil Film ◽  
Return Spring ◽  
Simulation Results ◽  
Friction Surfaces

Abstract Oil immersed clutches are often treated without respect to the oil being present, i.e. the torque is assumed to be a pure dry friction torque, directly controlled by the actuating force. However, during the engagement this is sometimes not enough. The oil film acts in two ways: Firstly, the oil has to be squeezed out before dry friction can be developed. Secondly, before the friction surfaces have reached contact, the torque is viscous. This work proposes equations that take these phenomena into account. A simple model for the transition from viscous to dry friction is used. Compensation for grooves in the friction surface is made. Also the hydraulic actuating equipment (piston, return spring, orifice etc.) is modelled. Simulation results are verified by experiments.

Friction Coefficient as a Macroscopic View of Local Dissipation

2007 ◽  
Author(s):  
I. Iordanoff ◽  
D. Richard ◽  
M. Renouf ◽  
Y. Berthier
Keyword(s):  
Friction Coefficient ◽  
Dry Friction ◽  
Three Dimensional ◽  
Global Scale ◽  
Contact Interface ◽  
Third Body ◽  
The Third ◽  
Dynamic Friction Coefficient ◽  
Set Up ◽  
Method Approach

This paper presents an overview of a Discrete Element Method approach used to study the dry friction (global scale) taking into account local discontinuity with the presence of third body at the contact interface. Three dimensional computer simulations have been carried out to show the influence of the third body properties (and more specifically its adhesion) on the resulting friction coefficient as well as the dissipated power profiles. The physics of the interface is described by a simple cohesive contact law which is set up to uncouple the key parameters governing the contact rheology. The model is validated through a global energy balance. As it is shown that dynamic friction coefficient can be explained in term of local energy dissipation, the work also emphasizes the fact that mechanism effects and third body rheology have important consequences on the energy generation and dissipation field. The friction coefficient cannot be considered the same way at the mechanism scale than at the contact one where the third body plays a non-negligible role despite the fact that it has been neglected for years in thermal approaches of the contact.

Third Body Concept and Wear Particle Behavior in Dry Friction Sliding Conditions

2015 ◽  
Vol 640 ◽  
pp. 1-12 ◽  
Author(s):  
Jean Denape
Keyword(s):  
Dry Friction ◽  
Friction And Wear ◽  
Wear Particle ◽  
Phenomenological Approach ◽  
Wear Particles ◽  
Third Body ◽  
Practical Applications ◽  
The Third ◽  
Body Concept ◽  
Synthetic View

The third body concept is a pragmatic tool for analyzing and understanding the friction and wear of sliding materials. This approach is based on the dominating role played by the wear particles under dry sliding conditions. These particles constitute the major part of what is called the third body. The third body concept was introduced by Maurice Godet in the middle of the 70’s and developed by Yves Berthier since the end of the 80’s who added complementary conceptual tools as the tribological triplet, the accommodation mechanisms and the tribological circuit. The aim of this paper is to give a synthetic view of these concepts, which involves mechanical, material and physicochemical subjects. Concrete examples and case studies from various practical applications are given to illustrate the validity and the efficiency of such a phenomenological approach.

Investigation of Changing of Chemical and Phase Composition of the Friction Surface Fe-Mn-C-B-Si-Ni-Cr

2018 ◽  
Vol 759 ◽  
pp. 65-68
Author(s):  
Mykhaylo Paszeczko ◽  
Klaudiusz Lenik ◽  
Krzysztof Dziedzic ◽  
Marcin Barszcz
Keyword(s):  
Phase Composition ◽  
Electron Microscope ◽  
Photoelectron Spectroscopy ◽  
Dry Friction ◽  
Friction Surface ◽  
X Ray ◽  
Pin On Disc ◽  
Xps Study ◽  
Friction Surfaces ◽  
Scanning Electron

The paper presents the results of a SEM/EDS and XPS study of changing of chemical and phase composition of the friction surfaces Fe-Mn-C-B-Si-Ni-Cr hardfacing coatings depend on depth. The tribological examination was conducted in a pin-on disc system with unitary pressure of 10 MPa under dry friction conditions. A scanning electron microscope SEM/EDS as well as X-Ray photoelectron spectroscopy (XPS) were used to examine the structures on the friction surface and depend on depth 5, 10, 15, 20, 50, 100, 200, 6000 nm. The presence of compounds such as oxides (B2O3, SiO2, Cr2O3), carbides (Fe3C, Cr7C3), borides (FeB, Fe2B).

Friction and Wear Behaviors of GCr15 Steel under Dry Friction and Grease Lubrication

2015 ◽  
Vol 1096 ◽  
pp. 132-135
Author(s):  
Bing Su ◽  
Shuo Zhang
Keyword(s):  
Dry Friction ◽  
Friction Surface ◽  
Friction And Wear ◽  
Sliding Friction ◽  
Friction Pair ◽  
Sem Analysis ◽  
Grease Lubrication ◽  
Gcr15 Steel ◽  
Scanning Electron ◽  
Ball On Disc

The sliding friction and wear behaviors of GCr15 steel against GCr15 steel under dry friction and grease lubrication were investigated on a reciprocating friction and wear tester consisting of a ball-on-disc friction pair. The morphologies of the worn surfaces of discs were analyzed by means of scanning electron microscopy (SEM). The result shows that GCr15 steel friction coefficient decreases with the increase of load, and the wear rate decreases with the time going by. There exist larger wear volumes on the friction surface under dry friction, while the wear volumes are relatively minor under grease lubrication. The SEM analysis agree with such results.

Effect of Incremental Copper Powders Third Body on Friction Properties of Q235 Steel

2011 ◽  
Vol 148-149 ◽  
pp. 1567-1571 ◽  
Author(s):  
Hua Li Liu ◽  
Fei Gao ◽  
Wan Hua Nong ◽  
Rong Fu
Keyword(s):  
Composite Materials ◽  
Friction Surface ◽  
Third Body ◽  
Q235 Steel ◽  
The Third ◽  
Copper Powders ◽  
Effect Of Copper ◽  
Frictional Coefficients ◽  
Pin On Disk

To understand the effects of the third body of copper in the copper-based composite materials on the friction properties, the effect of copper powders on the friction properties of Q235 steel is studied by using the pin-on-disk tester and adding copper powders third body. The results show that when the friction speed at 500-3000 r/min, due to the incremental copper powders, the depth of the furrows on the friction surface was reduced and the adhesion and spalling process of surface third body were intensified, which results that the frictional coefficients of the Q235 steel are increased 0.2-0.35 comparing with that of without adding copper powders. The reason is that incremental copper third body plays the role of increasing the meshing of the asperity and the actual friction area.

Electron microscopic studies on ultrathin frozen sections of lactating mouse mammary gland

1978 ◽  
Vol 36 (2) ◽  
pp. 46-47
Author(s):  
Jan Zarzycki ◽  
Joseph Szroeder
Keyword(s):  
Mammary Gland ◽  
Protein Denaturation ◽  
Chemical Constituents ◽  
Freeze Substitution ◽  
Electron Microscopic Examination ◽  
Mouse Mammary Gland ◽  
Electron Microscopic ◽  
Preparation Methods ◽  
Microscopic Studies ◽  
Ultrathin Frozen Sections

The mammary gland ultrastructure in various functional states is the object of our investigations. The material prepared for electron microscopic examination by the conventional chemical methods has several limitations, the most important are the protein denaturation processes and the loss of large amounts of chemical constituents from the cells. In relevance to this,one can't be sure about a degree the observed images are adequate to the realy ultrastructure of a living cell. To avoid the disadvantages of the chemical preparation methods,some autors worked out alternative physical methods based on tissue freezing / freeze-drying, freeze-substitution, freeze-eatching techniqs/; actually the technique of cryoultraraicrotomy,i,e.cutting ultrathin sections from deep frozen specimens is assented as a complete alternative method. According to the limitations of the routine plastic embbeding methods we were interested to analize the mammary gland ultrastructure during lactation by the cryoultramicrotomy method.

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