The document provides an overview of metal matrix composites (MMCs). It discusses that MMCs consist of a metal matrix reinforced with ceramic particles or fibers. The reinforcement improves the composite's properties over the unreinforced metal, such as increased strength and stiffness. The document also examines the important interfaces between the matrix and reinforcement, which influence the composite's performance. It describes various bonding mechanisms at the interface like mechanical, chemical, and diffusion bonding. Finally, the document outlines common processing techniques for fabricating MMCs, including powder metallurgy where metal powders are compacted and sintered to form the final composite material.
Composite Materials are widely used in day today life and as well as in automotive and aerospace industry which are monolithic composites.but most of the monolithic composites are not able to achieve required mechanical properties,so to achieve those mechanical properties Metal Matrix composites widely used in different sectors.some of Compiled information on MMC are presented in this presentation.
Metal matrix composites (MMCs) possess significantly improved properties including highspecific strength; specific modulus, damping capacity and good wear resistance compared to unreinforced alloys. There has been an increasing interest in composites containing low density and low cost reinforcements. Among various discontinuous dispersoids used, fly ash is one of the most inexpensive and low density reinforcement available in large quantities as solid waste by-product during combustion of coal in thermal power plants. Hence, composites with fly ash as reinforcement are likely to overcome the cost barrier for wide spread applications in automotive and small engine applications.
Composite Materials are widely used in day today life and as well as in automotive and aerospace industry which are monolithic composites.but most of the monolithic composites are not able to achieve required mechanical properties,so to achieve those mechanical properties Metal Matrix composites widely used in different sectors.some of Compiled information on MMC are presented in this presentation.
Metal matrix composites (MMCs) possess significantly improved properties including highspecific strength; specific modulus, damping capacity and good wear resistance compared to unreinforced alloys. There has been an increasing interest in composites containing low density and low cost reinforcements. Among various discontinuous dispersoids used, fly ash is one of the most inexpensive and low density reinforcement available in large quantities as solid waste by-product during combustion of coal in thermal power plants. Hence, composites with fly ash as reinforcement are likely to overcome the cost barrier for wide spread applications in automotive and small engine applications.
Metal matrix composites with high specific stiffness and strength could be used in applications in which saving weight is an important factor. Included in this category are robots, high-speed machinery, and high-speed rotating shafts for ships
or land vehicles. Good wear resistance, along with high specific strength, also favors MMC use in automotive engine and brake parts. Tailorable coefficient of thermal expansion and thermal conductivity make them good candidates for lasers, precision machinery, and electronic packaging.
However, the current level of development effort appears to be inadequate to bring about the commercialization of any of these in the next 5 years, with the possible exception of diesel engine
pistons.
Image result for metal matrix composites
www.slideshare.net
A metal matrix composite (MMC) is composite material with at least two constituent parts, one being a metal necessarily, the other material may be a different metal or another material, such as a ceramic or organic compound. When at least three materials are present, it is called a hybrid composite.
LARGE PARTICLE REINFORCED COMPOSITE ,,,An Overview
Seminar done as a part of METALLURGY AND MATERIAL SCIENCE.
Good PPT to study,
included most of the points to study
HASEEB KM
S3 ME
MUTHOOT INSTITUTE OF TECHNOLOGY AND SCIENCE, COCHIN
The important points of composite materials are mentioned. This file includes, what is composite materials, its classifications, applications, advantages and disadvantages.
The fabrication methodology of a composite part depends mainly on three factors:
(i) the characteristics of matrices and reinforcements,
(ii) the shapes, sizes and engineering details of products, and
(iii) end uses.
The composite products are too many and cover a very wide domain of applications ranging from an engine valve to an aircraft wing.
The fabrication technique varies from one product to the other.
Metal matrix composites with high specific stiffness and strength could be used in applications in which saving weight is an important factor. Included in this category are robots, high-speed machinery, and high-speed rotating shafts for ships
or land vehicles. Good wear resistance, along with high specific strength, also favors MMC use in automotive engine and brake parts. Tailorable coefficient of thermal expansion and thermal conductivity make them good candidates for lasers, precision machinery, and electronic packaging.
However, the current level of development effort appears to be inadequate to bring about the commercialization of any of these in the next 5 years, with the possible exception of diesel engine
pistons.
Image result for metal matrix composites
www.slideshare.net
A metal matrix composite (MMC) is composite material with at least two constituent parts, one being a metal necessarily, the other material may be a different metal or another material, such as a ceramic or organic compound. When at least three materials are present, it is called a hybrid composite.
LARGE PARTICLE REINFORCED COMPOSITE ,,,An Overview
Seminar done as a part of METALLURGY AND MATERIAL SCIENCE.
Good PPT to study,
included most of the points to study
HASEEB KM
S3 ME
MUTHOOT INSTITUTE OF TECHNOLOGY AND SCIENCE, COCHIN
The important points of composite materials are mentioned. This file includes, what is composite materials, its classifications, applications, advantages and disadvantages.
The fabrication methodology of a composite part depends mainly on three factors:
(i) the characteristics of matrices and reinforcements,
(ii) the shapes, sizes and engineering details of products, and
(iii) end uses.
The composite products are too many and cover a very wide domain of applications ranging from an engine valve to an aircraft wing.
The fabrication technique varies from one product to the other.
Seminar on tribological behaviour of alumina reinfoeced composite material na...Sidharth Adhikari
THIS SEMINAR IS ON TRIBOLOGY BEHAVIOR OF ALUMINA REINFOCED COMPOSITE MATERIAL AND BRAKE DISK MATERIAL
MTECH SECOND SEMESTER SEMINAR ,CENTRE FOR ADVANCE POST-GRADUATE STUDIES,BPUT,ROURKELA
If we mix a group of oils with insect repellent nature with some of the pungent smell of plants and the formation of a homogeneous mixture of them will be able to repel insects with the preservation of the environment and the security of the human.
Fabrication and Wear Behavior of Particulate Reinforced Metal Matrix Composit...IOSRJMCE
The composites refer to the material consisting of two or more individual constituents, in that the reinforcing particulates are embedded to the base matrix to form composite materials by improving the mechanical and tribological properties. Different types of composite materials are available and these are increasing because of their good enhanced properties, among these Metal Matrix Composites (MMCs) finds its applications in various aspects like aerospace, automotive, defense, and marine etc. These improved properties are obtained from different form of particulates which are different in their aspect ratio are mixed with base material to provide good bonding and strength between them. To obtain these enhanced properties different manufacturing techniques are followed to prepare the composites. This paper presents an overview of types of composites, different fabrication techniques available to prepare the composites and also wear behavior of particulates reinforced MMC’s by studying different types of wear mechanism.
EFFECT OF NANO RUBBER ADDITIONS ON WEAR AND MECHANICAL PROPERTIES OF EPOXY GL...paperpublications3
Abstract: The use of polymer fiber reinforced composite materials is growing day by day in all types of engineering structures such as aerospace, automotive, aircraft, chemical, constructions etc. because of their tailorable properties. Through these materials are tailorable, improvement in tribological properties is demanded.Keywords:epoxy glass fiber composites, nano nitrile butadiene rubber particles.
EFFECT OF NANO RUBBER ADDITIONS ON WEAR AND MECHANICAL PROPERTIES OF EPOXY GL...paperpublications3
Abstract: The use of polymer fiber reinforced composite materials is growing day by day in all types of engineering structures such as aerospace, automotive, aircraft, chemical, constructions etc. because of their tailorable properties. Through these materials are tailorable, improvement in tribological properties is demanded.Keywords:epoxy glass fiber composites, nano nitrile butadiene rubber particles.
Design Fabrication and Static Analysis of Single Composite Lap Jointijsrd.com
Mechanically fastened joints are critical parts in composite aircraft structures. The composite structural members are highly used in the following applications such as aerospace, automobiles, marine, architecture etc., In the past decades, Adhesive bonding is a practical joint method for joining composite materials which provide low shear and Tensile strength .To improve the strength material joint is to be used in the work. A Glass fibre Epoxy composite is to be fabricated by hand lay-up method. And experimentally results are to be obtained. The Experimental results are to be compared with Analytical and Numerical results. For numerical analysis ANSYS software is to be used.
Review of Effective Parameters of Stir Casting Process on Metallurgical Prope...iosrjce
IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of mechanical and civil engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in mechanical and civil engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Damping Of Composite Material Structures with Riveted JointsIJMER
Vibration and noise reduction are crucial in maintaining high performance level and
prolonging the useful life of machinery, automobiles, aerodynamic and spacecraft structures. It is
observed that damping in materials occur due to energy release due to micro-slips along frictional
interfaces and due to varying strain regions and interaction between the metals. But it was found
that the damping effect in metals is quite small that it can be neglected. Damping in metals is due to
the micro-slips along frictional interfaces. Composites, however, have better damping properties
than structural metals and cannot be neglected. Typically, the range of composite damping begins
where the best damped metal stops.In the present work, theoretical analysis was done on various
polymer matrix composite (glass fibre polyesters) with riveted joints by varying initial conditions.
Strain energy loss was calculated to calculate the damping in composites. Using FEA model, load
variation w.r.t time was observed and the strain energy loss calculated was utilised in finding the
material damping for Carbon fibre epoxy with riveted joints. Various simulations were performed in
ANSYS and these results were utilised to calculate the loss factor, Rayleigh‘s damping constants
and logarithmic decrement.
IMPACT OF AL-COMPOSITES IN THE MANUFACTURING INDUSTRY: A NECCESSITYIAEME Publication
In the engineering sector today, the need to substitute for orthodox materials like
wood, aluminium, steel and concrete, has led to the invention of raw materials that
meet specific needs like hardiness-to-mass ratio, i.e. increased strength and light
weight, increased strength of impact, dimensional constancy and resistance to
corrosion. These materials are called composites. In this paper, we have assessed
several articles by a number of researchers on the impact of composites in the
manufacturing industry, making aluminium composites our focus. This review studied
the properties, behaviours, applications, advantages and setbacks, of aluminium
composites. From this study, it was observed that the automotive industry makes the
most use of aluminium composites, for the manufacture of parts like pistons and
connecting rods. However, processing of Al-dependent MMC’s is costlier than other
raw materials. And this is a major setback in the use of aluminium composites in the
manufacturing industry
IMPACT OF AL-COMPOSITES IN THE MANUFACTURING INDUSTRY: A NECCESSITYIAEME Publication
In the engineering sector today, the need to substitute for orthodox materials like wood, aluminium, steel and concrete, has led to the invention of raw materials that meet specific needs like hardiness-to-mass ratio, i.e. increased strength and light weight, increased strength of impact, dimensional constancy and resistance to corrosion. These materials are called composites. In this paper, we have assessed several articles by a number of researchers on the impact of composites in the manufacturing industry, making aluminium composites our focus. This review studied the properties, behaviours, applications, advantages and setbacks, of aluminium composites. From this study, it was observed that the automotive industry makes the most use of aluminium composites, for the manufacture of parts like pistons and connecting rods. However, processing of Al-dependent MMC’s is costlier than other raw materials. And this is a major setback in the use of aluminium composites in the manufacturing industry.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Fabrication, charecterization and development of high damping materials for n...eSAT Journals
Abstract Aluminum matrix composites are early inventions during 60’s. Presently these are used as railroad equipment and aerospace components. Their application has shown no further growth during the last decade due to lack of toughness. The non-compatibility between the matrix and the reinforcement and lack of good interface among these led to the reduced ductility levels. The limited solubility leads to the alloy formation passing solid solution strengthening while the un dissolved particles help achieving dispersion strengthening. Instead of taking ceramic particulates as reinforcements, metallic reinforcements were dispersed in aluminium matrix. Damping characteristics were calculated for the alloy and composites. Suitable heat treatment enhances the properties of the composite further. The expected mechanical properties will be higher than the regular alloys, which can be useful for various components in naval applications where high damping is required. Keywords: Dispersion Strengthening, Damping.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
2. CONTENTS.
INTRODUCTION
Composite
Classification of Composites
Metal Matrix Composites (MMC)
INTERFACES COMPOSITEs
Mechanical bonding
Electrostatic bonding
Chemical bonding
Reaction or interdiffusion bonding
PROCESSING OF METAL MATRIX COMPOSITES
Powder metallugry 2
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3. INTRODUCTION
Composites are composed of two or more different materials
to obtain a combination of properties not available in either
of the materials.
Usually one material forms a continuous matrix while the
other provides the reinforcement.
The two materials must be chemically inert with respect to
each other so no interaction occurs on heating until one of
the components melts.
An exception to this condition is a small degree of
interdiffusion at the reinforcement-matrix interface to
increase bonding.
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5. Functions of the Matrix Material
Provides the bulk form of the part or product made of
the composite material
Holds the imbedded phase in place, usually enclosing
and often concealing it
When a load is applied, the matrix shares the load with
the secondary phase, in some cases deforming so that
the stress is essentially born by the reinforcing agent
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6. Functions of the Reinforcing Phase
Function is to reinforce the primary phase
Imbedded phase is most commonly one of the following
shapes:
Fibers
Particles
Flakes
In addition, the secondary phase can take the form of an
infiltrated phase in a skeletal or porous matrix – Example:
a powder metallurgy part infiltrated with polymer
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7. Metal Matrix Composites (MMCs)
Materials consisting of metallic matrices, reinforced with
ceramic particles or fibers, are known as metal matrix
composites or MMCs
The volume fraction of the reinforcement is typically in the
range 10-70%.
MMCs can offer a range of property enhancement over
monolithic alloys.
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8. Metal Matrix Composites (MMCs)
A metal matrix reinforced by a second phase
Reinforcing phases:
Particles of ceramic (these MMCs are commonly called
cermets)
Fibers of various materials: other metals, ceramics, carbon,
and boron
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9. Metal Matrix Composites (MMCs)
Metal matrix composite materials have found application in
many areas of daily life for quite some time.
Materials like cast iron with graphite or steel with a high
carbide content, as well as tungsten carbides, consisting of
carbides and metallic binders, also belong to this group of
composite materials.
Metal matrix composites become interesting for use as
constructional and functional materials, if the property profile
of conventional materials either does not reach the increased
standards of specific demands, or is the solution of the
problem.
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10. Metal Matrix Composites (MMCs)
The reinforcement of metals can have many different objectives;
Increase in yield strength and tensile strength at room
temperature and above while maintaining the minimum ductility
or rather toughness,
Increase in creep resistance at higher temperatures compared to
that of conventional alloys,
Increase in fatigue strength, especially at higher temperatures,
Improvement of thermal shock resistance,
Improvement of corrosion resistance
Increase in Young’s modulus,
Reduction of thermal elongation.
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12. Classification of Metal Matrix Composites
Metal Matrix
Composites(MMCs)
Dispersion
hardened and
particles
Layer
composites
Fiber
composites
Infiltration
composites
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13. Reinforcements for Metal Matrix
Composites
These demands can be achieved only by using non-metal
inorganic reinforcement components. For metal reinforcement
ceramic particles or, rather, fibers or carbon fibers are often used.
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14. Interfaces (Bonding)
There is always an interface between constituent phases in a
composite material †
For the composite to operate effectively, the phases must bond
where they join at the interface
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Interfaces between phases in a composite material: (a) direct
bonding between primary and secondary phases; (b) addition of a
third ingredient to bond the primary phases and form an interphase.
15. Interfaces (Bonding)
Interphase consisting of a solution of primary and secondary
phases
Interfaces and interphases between phases in a composite
material: (c) formation of an interphase by solution of the
primary and secondary phases at their boundary.
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15
16. Interfaces (Bonding)
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16
Why are Reinforcement matrix interfaces important?
Such large differences are shared through the interface.
Stresses acting on the matrix are transmitted to the fiber across the
interface.
The interfacial bond can influence
• Composite strength
• Modes of failure
• Young’s modulus
• Interlaminar shear strength
• Compressive strength
• Environmental resistance
• Structural stability at elevate temperatures
• Fracture and fatigue behavior
17. Interfaces (Bonding)
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17
Wettability
Is defined the extent where a liquid will spread over a solid
surface
During the manufacturing process, the matrix is often in the
condition where it is capable of flowing or its behavior is like a
liquid
Good wettability means that the liquid (matrix) will flow over
the reinforcement, covering every ‘bump’ and ‘dip’ of the rough
surface of reinforcement and displacing all air.
Wetting will only occur if the viscosity of the matrix is not too
high.
Interfacial bonding exists due to the adhesion between the
reinforcement and the matrix (wetting is good)
18. Interfaces (Bonding)
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18
All surfaces have an associated energy and the free energy per
unit area of the solid-gas, liquid-gas and solid-liquid are γSG,
γLG and γSL,
θ is called the contact angle. May be used as a measure of the
degree of the wettability
19. Interfaces (Bonding)
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19
Types of interfacial bonding at interface
Mechanical bonding
Electrostatic bonding
Chemical bonding
Reaction or inter-diffusion bonding
20. Interfaces (Bonding)
Depending on degree of roughness of fiber surface †
Larger surface area may also increase strength of chemical
bond.
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20
Mechanical bonding
21. The bond formed between chemical groups on the reinforcement
surfaces and compatible groups in the matrix
Strength of chemical bonding depends on the number of bonds per
unit area and the type of bond
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21
Interfaces (Bonding)
Chemical bonding
22. Diffusion and entanglement of molecules
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22
Interfaces (Bonding)
Reaction or interdiffusion bonding
23. Occur when one surface is positively charged and the other is
negatively charge (refer to the figure)
Interactions are short range and only effective over small
distances of the order of atomic dimensions
Surface contamination and entrapped gases will decrease the
effectiveness of this bonding
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23
• Electrostatic bonding
Interfaces (Bonding)
24. Processing of Metal Matrix
Composites
Metal matrix composites materials can be produced by
many different techniques.
The focus of the selection of suitable process engineering
is the desired kind, quantity and distribution of the
reinforcement components (particles and fibers), the matrix
alloy and the application.
By altering the manufacturing method, the processing and
the finishing, as well as by the form of the reinforcement
components it is possible to obtain different characteristic
profiles, although the same composition and amounts of
the components are involved.
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26. Solid-State Processes
Powder Processing
• Powder metallurgy: Science of producing metal powders
and making finished /semifinished objects from mixed or
alloyed powders with or without the addition of nonmetallic
constituents
• Steps in powder metallurgy : Powder production,
Compaction, Sintering, Secondary operations
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27. 11/3/2016
27
Elemental or Alloy
metal powders
Additives
(lubricants or binders)
Blending and
Mixing
Compacting
Sintering
Optional Secondary
Finishing
Optional Secondary
Manufacturing
Finished Powder
Metallurgy Product
29. Production of powders
• Cheapest of the powder production methods.
• These methods involve using mechanical forces such as
compressive forces, shear or impact to facilitate particle size
reduction of bulk materials. Ex: Milling
• Milling: During milling, impact, attrition, shear and
compression forces are acted upon particles
• Impact : Striking of one powder particle against another
occurs.
• Attrition : The production of wear debris due to the rubbing
action between two particles.
• Shear: Cutting of particles resulting in fracture.
• Compression :The particles are broken into fine particles by
squeezing action in compression
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Mechanical methods
30. Production of powders
• Main objective of milling: Particle size reduction (main
purpose), Particle size growth, shape change, agglomeration
(joining of particles together), solid state alloying,
mechanical or solid state mixing, modification of material
properties.
• Mechanism of milling: Changes in the morphology of
powder particles during milling results in the following
events.
• Micro forging
• Fracture
• Agglomeration
• Deagglomeration
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31. Production of powders
• Micro forging: Individual particles or group of particles are
impacted repeatedly so that they flatten with very less change
in mass
• Fracture : Individual particles deform and cracks initiate and
propagate resulting in fracture
• Agglomeration : Mechanical interlocking due to atomic
bonding or vande Waals forces
• Deagglomeration : Breaking of agglomerates
• The different powder characteristics influenced by milling are
shape, size, texture, particle size distribution, crystalline size,
chemical composition, hardness, density, flowability,
compressibility, sinterability, sintered density
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32. Production of powders
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The particle are work hardened, the fracture mechanism are
predominate the cold weld, thus particles size decreased
the particles weld together due to the impacts of grinding balls to
form larger particle
The start power are soft, easy flattened as flake
33. 11/3/2016
33
Blending and Mixing
• Blending : mixing powder of the same chemical
composition but different sizes.
• Mixing : combining powders of different chemistries.
• Blending and mixing are accomplished by mechanical
means:
34. Blending and Mixing
• Except for powders, some other ingredients are usually
added:
Lubricants: to reduce the particles-die friction
Binders: to achieve enough strength before sintering
Deflocculants : to improve the flow characteristics
during feeding
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35. Compaction
• Blended powers are pressed in dies under high pressure to form
them into the required shape. The work part after compaction is
called a green compact or simply a green.
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36. Compaction
• As a result of compaction, the density of the part, called the
green density is much greater than the starting material density,
but is not uniform in the green. The density and therefore
mechanical properties vary across the part volume and depend on
pressure in compaction.
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37. Sintering
• Compressed metal powder is heated in a controlled-
atmosphere furnace to a temperature below its melting
point, but high enough to allow bounding of the particles:
• Purpose : to increase strength & hardness of a green
compact
• Principal variables : temperature ( generally within 70 –
90% of the melting point of metal or alloy), time (10 min.
– 8 hours) & furnace atmosphere
• Sintering process is concerned with
• diffusion (surface of particles as temperature rises)
• densification (decreases porosity, increases particle contact area)
• recrystallization & grain growth (between particles at the contact
area)
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38. Sintering
• The primary driving force for sintering is not the fusion
of material, but formation and growth of bonds between
the particles, as illustrated in a series of sketches showing
on a microscopic scale the changes that occur during
sintering of metallic powders.
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40. FINISHING / SECONDARYOPERATIONS
1.Sizing : cold pressing to improve dimensional accuracy
2.Coining or pressing :
• cold working process, to press details into surface
• condensation of sintered product
3.Impregnation:
• impregnation with heated oil (self lubricated bearings)
• oil fills the pores of the part
4.Infiltration:
• placement of slug of a lower melting point metal against the
sintered part
• infiltration of molten metal by capillary action
• pores are filled with a molten metal
5.Heat treatment , Plating, Painting
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41. Advantages
• Elimination/reduction of machining
• High production rates
• Complex shapes can be produced
• Wide composition variations are possible
• Wide property variations are possible
• Scrap is eliminated or reduced
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42. Disadvantages
• High cost of powder material & tooling
• Less strong parts than wrought ones
• Less well known process
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