Tribochemical wear occurs due to chemical reactions between contacting surfaces that are accelerated by friction and heat. It is a complex wear mechanism that involves both mechanical and chemical processes. Flash temperatures generated during sliding can significantly increase reaction kinetics and lead to oxidation. Tribochemical wear can produce both protective surface layers that reduce wear, as well as abrasive debris. Effective ways to prevent tribochemical wear include using lubricants, hard coatings like DLC that form protective layers, and increasing the hardness of materials.
This book offers fundamentals and a comprehensive overview of tribology in sever conditions. It addresses a comprehensive coverage of classical tribology of solid contacts, friction mechanics, wear mechanisms and lubrication technologies. Characteristics of tribological systems operating under extreme conditions involving extraordinary loads, temperatures, speeds, and vacuum are discussed. Surface coating, surface treatment, and lubrication are argued considering the cutting-edge researches. In addition, tribology of automotive components is presented, as are tribological applications in many practical situations. The tribology of polymer composites, MEMS and NEMS are explored. A basic understanding of failure in tribological systems is covered. Various test methods used in evaluating wear are reviewed. Diverse techniques applied in predicting wear behavior by mathematical models, FE modeling and ANN approach are discussed.
Degradation of an object occurs as a result of the interaction between the environment or with the materials that form the object however, in the case of ceramics, environmental factors are the major cause. There are several ways in which ceramics break down physically and chemically.
Tribology assignment regarding the fundamentals of friction, containing: Introduction
Rules of Friction
Exceptions
Mechanism
Cases of Friction
Friction of common materials
& Conclusion
The objective of this course is to provide a basic overview of failure analysis. It will include discussion of failure mechanisms, analytical techniques and case histories
• To provide you with a clear understanding of terms used so that you can ask the right questions and interpret common observations with ease
Types of failures
Failure modes
How to conduct failure analysis
Analyze data
Failure mechanism
Prevention of Failures
Failures examples
Wear is a process of removal of material from one or both of two solid surfaces in solid state contact, occurring when these two solid surfaces are in sliding or rolling motivation
This seminar provides a very comprehensive and up-to-date overview of the rapidly expanding field of tribology. First friction, wear, and lubrication including a brief historical evolution of tribology over millennia will be introduced and described in detail. Progressively, the properties and main characteristics of tribological surfaces where friction, wear, and lubrication take place will be addressed, also various methods used for measuring surface roughness, mechanical, chemical, and physical properties all of which are critically important for the tribological performance of all moving mechanical systems will be described. A section on friction and wear introduces basic concepts, theories, mechanisms involved and in minimizing friction and wear. The friction and wear of specific material groups or classes are presented to further emphasize the fact each material type or coating can differ from one another in their friction and wear behaviors mainly because of the stark differences in their structural, chemical, mechanical, and physical properties.
The seminar will then focus on the topic of tribology in extreme environmental conditions. Space tribology as one of the tribology challenges in such working conditions will be overviewed. Characteristics of tribological systems operating under extreme conditions involving extraordinary temperatures, speeds, and vacuum are discussed.
This book offers fundamentals and a comprehensive overview of tribology in sever conditions. It addresses a comprehensive coverage of classical tribology of solid contacts, friction mechanics, wear mechanisms and lubrication technologies. Characteristics of tribological systems operating under extreme conditions involving extraordinary loads, temperatures, speeds, and vacuum are discussed. Surface coating, surface treatment, and lubrication are argued considering the cutting-edge researches. In addition, tribology of automotive components is presented, as are tribological applications in many practical situations. The tribology of polymer composites, MEMS and NEMS are explored. A basic understanding of failure in tribological systems is covered. Various test methods used in evaluating wear are reviewed. Diverse techniques applied in predicting wear behavior by mathematical models, FE modeling and ANN approach are discussed.
Degradation of an object occurs as a result of the interaction between the environment or with the materials that form the object however, in the case of ceramics, environmental factors are the major cause. There are several ways in which ceramics break down physically and chemically.
Tribology assignment regarding the fundamentals of friction, containing: Introduction
Rules of Friction
Exceptions
Mechanism
Cases of Friction
Friction of common materials
& Conclusion
The objective of this course is to provide a basic overview of failure analysis. It will include discussion of failure mechanisms, analytical techniques and case histories
• To provide you with a clear understanding of terms used so that you can ask the right questions and interpret common observations with ease
Types of failures
Failure modes
How to conduct failure analysis
Analyze data
Failure mechanism
Prevention of Failures
Failures examples
Wear is a process of removal of material from one or both of two solid surfaces in solid state contact, occurring when these two solid surfaces are in sliding or rolling motivation
This seminar provides a very comprehensive and up-to-date overview of the rapidly expanding field of tribology. First friction, wear, and lubrication including a brief historical evolution of tribology over millennia will be introduced and described in detail. Progressively, the properties and main characteristics of tribological surfaces where friction, wear, and lubrication take place will be addressed, also various methods used for measuring surface roughness, mechanical, chemical, and physical properties all of which are critically important for the tribological performance of all moving mechanical systems will be described. A section on friction and wear introduces basic concepts, theories, mechanisms involved and in minimizing friction and wear. The friction and wear of specific material groups or classes are presented to further emphasize the fact each material type or coating can differ from one another in their friction and wear behaviors mainly because of the stark differences in their structural, chemical, mechanical, and physical properties.
The seminar will then focus on the topic of tribology in extreme environmental conditions. Space tribology as one of the tribology challenges in such working conditions will be overviewed. Characteristics of tribological systems operating under extreme conditions involving extraordinary temperatures, speeds, and vacuum are discussed.
Study of sliding wear rate of hot rolled steel specimen subjected to Zirconia...IJERA Editor
Wear is nothing but loss of material by usage. In a mechanical industry mechanical components will operate
under severe load, temperature and high speeds. Under such a type of situation, when metal to metal contact take
place the surfaces that comes in contact is subjected to wear. These should be considered as a serious affair in an
industry because if the process of wear continues it can reduce service life of the component and also to the
entire mechanical system to which the component has been used. In the light of the above the present work
mainly deals with the study of wear behavior of hot rolled steel with and without zirconia coating on the contact
surface and the effect of zirconia coating with varying thickness.
Friction and wear are two key factors that are detrimental at the nanoscale, because they are linked with surface forces. It is important to understand their mechanisms and to find ways to overcome them. At the macroscale lubricant are classically used to do so and are well understood. However, those lubricants cannot be readily used at the nanoscale and other lubrication methods must be found. In this paper I will focus on two new potential lubricants that were tested in Microelectromechanical Systems (MEMS): ionic liquid films and alcohol vapor. They are both very different and are not used in the same situations but they both show great potential. In fact, thanks to the alcohol vapor lubricant a device did not show signs of wear after 11 days of operation, whereas it failed within minutes in the absence of alcohol. No signs of wear were seen after 100 cycles of operation of a device with ionic liquid film but were observed in an uncoated device.
Lec3 failure.pptx introductionto fialure types and causesssuserac3f5b
define the term failure. types of failures and mechanisms, failure modes. failure mode and criticality analysis.
Failure mechanisms are physical, chemical, or other processes which lead or have led to failure.
A CRITICAL REVIEW ON DIFFERENT TYPES OF WEAR OF MATERIALSIAEME Publication
Many mechanical equipments are subjected to sliding contact in real time applications. Pumps, valves, belt drives, bearings, machinery guide ways, piston- cylinder arrangements etc. are the few important sliding components which are continuously subjected to sliding wear. Much mechanical equipment’s failure occurred due to wear related problems.
Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
NO1 Uk best vashikaran specialist in delhi vashikaran baba near me online vas...Amil Baba Dawood bangali
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CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
Hierarchical Digital Twin of a Naval Power SystemKerry Sado
A hierarchical digital twin of a Naval DC power system has been developed and experimentally verified. Similar to other state-of-the-art digital twins, this technology creates a digital replica of the physical system executed in real-time or faster, which can modify hardware controls. However, its advantage stems from distributing computational efforts by utilizing a hierarchical structure composed of lower-level digital twin blocks and a higher-level system digital twin. Each digital twin block is associated with a physical subsystem of the hardware and communicates with a singular system digital twin, which creates a system-level response. By extracting information from each level of the hierarchy, power system controls of the hardware were reconfigured autonomously. This hierarchical digital twin development offers several advantages over other digital twins, particularly in the field of naval power systems. The hierarchical structure allows for greater computational efficiency and scalability while the ability to autonomously reconfigure hardware controls offers increased flexibility and responsiveness. The hierarchical decomposition and models utilized were well aligned with the physical twin, as indicated by the maximum deviations between the developed digital twin hierarchy and the hardware.
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
1. FUNDAMENTALS OF TRIBOCHEMICAL WEAR
TRIBOLOGY OF MATERIALS (CR-4102)
ASSIGNMENT
Submitted By:- Course Mentor:-
Sanket Kumar Dani Prof. Debasish Sarkar
118CR0673
Department of Ceramic Engineering
National Institute of Technology, Rourkela, 769008
2. INTRODUCTION:-
WEAR:-
It is defined as the continuous removal of materials from contacting surfaces in relative motion.
It actually results due to friction and occurs at the zone of contact.
The process of this wear can occur in a wide range of substances i.e metals ,non-oxides,ceramics and polymer.
Basically ,wear can be of three types based on the intensity of its damage and quality of material lost by an active
element;
• Mild wear:- It is one of the basic types of wear which has less loss or damage or we can say impact on the
materials.In this type of wear mechanism ,it involves the reaction with environment as a result of which there is
formation of oxides in the wear. In this the system is worn away very little , surface remains smooth and particles
have dimensions in order of micrometer.
• Severe wear :-In this type of wear the intensity of damage of materials is much more than normal wear ,which can
be calculated finally from the wear rate value. Also in this the body surfaces are changed and the size of particle
even exceed 100 micrometer.
• Catastrophic wear :- In this type of wear particularly life expectancy of the particle is reduced exponentially.
3. Wear rate :-
o It can be defined as the volume worn per unit load per unit traversed distance from contacting surfaces in relative
motion.
o Its unit is m3/Nm .
wear rate= (volume loss * hardness) / (sliding distance * applied load).
Factors that influences the level of wear are as follows :-
(i) Force of contact
(ii) Temperature
(iii) Area of contact between the contacting surfaces
(iv) Physio – Chemical state of surfaces in friction
(v) Crystallographic structure and material properties of materials ,one of them being the hardness.
Wear can proceed in several way in the materials ;that can be through plastic deformation in which there is creation ,
displacement of dislocations,impacts ,scratches will occur Or it can take the form of fracture as well in brittle materials
by intiation,accommodation,progression and propagation.
4. Origin of wear :-
Archard’s Experimental Law :-
According to Archard experimental law , the wear volume is proportional to the normal load , the sliding distance and
inversely proportional to the hardness of the contact materials.
Archard wear equation which is used to gain insight on wear is based on the theory of asperity contact.
where, Q or It can also be denoted as (Wv) = Total volume of wear produced
k= wear coefficient
W = Normal force or load
L = sliding distance or distance traversed
H = Hardness of the contacting surface
5. Types of wear mechanism :-
(i) Adhesive wear
(ii) Abrasive wear
(iii) Oxidative wear
(iv) Fretting wear
(v) Erosive wear
(vi) Tribochemical wear
-> For any technological applications , not single but combination of wear mechanisms are used.
-> Of the above mentioned wear mechanisms, one or more even maybe operating in one particular piece
of machinery. In many cases even these type of scenario arises where the wear is initiated by one
mechanism and it then proceed to other wear mechanisms which ultimately leads to complicacy in failure
analysis of wear.
6. TRIBOCHEMICAL WEAR :-
Frictional heating modifies the kinetics of chemical reaction.
Tribochemical wear is one of the most complex type of wear.
Tribochemistry can be defined as the chemistry that deals with the chemistry of chemical reactions by friction that
actually occur between the lubricant and the surface under boundary condition.
And the wear governed by these kinda reactions is called tribochemical wear.
Due to the result of mostly the friction in the chemical reactions , the extent of reactions of sliding bodies increased
as a resut of which reactions occurs at a higher temperature than normal temperature which is the main reason of
arise of this type of wear.
The most common method or mechanism by which friction increases the rate of chemical reactions is by producing
heat at contacting surface of asperities.
Tribochemical wear also results in oxidative wear of ceramics,metals and development of friction polymer films.
Tribochemical reaction is due to the chemical reactions but initiation may take place due to adhesive or abrasive
wear or other mechanical wear.
7. The interface temperature produced at the asperity contact during sliding of two counterbodies which is known as flash
temperature.
This temperature is basically responsible for thermal oxidation and produce oxide fims in the range of nanometer to several
micrometer.
At low temperature oxidation occurs at asperity contacts from frictional heating
Here the low temperature means the environmental temperature not the flash temperature.
Whereas,at high temperature generally the oxidation of entire surface occurs and affects wear .
Example – of tribochemical
wear of ceramic
cutting tool.
(a) Schematic drawing showing a tribologically induced transfer layer on the contact surface of the ceramic sample,
(b) SEM image of a cross section showing Tribochemical wear products on the ceramic contact tip.
8. A Tribological system basically consists of surface of two components that are in contact with one another or each other
and surrounding while moving .So, the progress, type and the extent of wear are determined by the materials and finishes
of the components ,any intermediate materials , influence of surrounding and the operating conditions.
Tribological System :-
(i) Base body
(ii) Opponent body
(iii)Influence of surrounding such as ;
Temp. , Relative humidity , pressure
(iv) Intermediate materials ; Oil , grease
water , contaminants , particles
(v) Load
(vi) Motion
9. In tribochemical wear mostly there is synergetic effect of chemistry as well as the mechanical wear ,that’s how it got its name
of tribochemical wear.
These chemical reactions in these wear are often not expected or feasible under the same temperature and static load
conditions;
Tribochemical reactions are also different from normally observed thermochemical reaction with respect to their kinetics as
this wear normally results from the removal of reaction products formed in situ from contacting surfaces.
Tribochemical wear Examples :-
• Tight fitting surfaces are particularly endangered with this type of wear.
• Tribochemical wear mostly observed in;
(i) Between race and shaft/ Housing and roller bearing
(ii) Bevel-wheels
(iii) Rivoted joints and clutches
(iv) Links of chain
(v) Plate springs etc.
10. Mechanisms of Tribochemical wear:-
The products that are formed during the chemical reactions of tribochemical wear are resulted mostly from the reaction of
solid surfaces with enivironment or between the mating materials.
If we take the instance of a metallic material system, the metallic contact of the surface asperities leads to removal of metal
due to adhesion.
Then the protective surface layer that is formed due to chemical reaction of metals with the environment will result in
reduction of metallic contact.
Then due to excess locally high pressure ,there is cracking of protective surface layer.
Metalic and non metallic wear debris may act as abrasive and roughen the contacting surface.Then finally formation of
protective layer may lead to smoothening of surfaces again.
11. Hong and its Co- workers developed a model for quantifying the wear loss due to tribochemical reactions (oxidation) .
where,
V or Wv = wear volume
A = Area of contact
Ai = Arrhenius Constant
Q = Activation energy
Rg = Molar Gas constant
Tf = Flash Temperature
p0 = Average density of the oxide in contact
fo = Mass fraction of the oxide
Ts = Sliding Time
12. Not always these tribochemical reactions are having negative impact on wear; there are also several times when these
tribochemical reactions are having positive impact on wear and those are mostly associated and designed for surface
protection and friction reduction.
These tribochemical layers also act as load bearing surfaces which posses low shearing strength, that results in low friction
and low wear.
Prevention from Tribochemical wear :-
o These tribochemical wear cannot be completely prevented but by effective process it can be reduced to certain extent and
for this lubricating and coating the surfaces are among the best methods.
o Generally the conventional lubricants that are essentially made for steel surfaces are mostly used for lubricating machine
surfaces or component surfaces having protective coating such as DLC’s( Diamond like carbon) .DLC’s comes under the
hard coatings which are still extensively used due to their relatively low friction and superior wear resistance compared to
other hard coatings. Oil and Grease are most commonly used for the purpose which helps in keeping the surfaces apart
from each other that helps in prevention of these wear.
o Another one of the conventional method of this wear reduction is by simply changing the material properties eg. By
hardening as we know that wear volume is inversely proportional to hardness.