Particle Particle Reinforced Reinforced CompositeComposite

INTRODUCTIONINTRODUCTION

COMPOSITES

Particle-Reinforced Composite

Fiber-Reinforced

Structural

IntroductionIntroduction A particle has no long dimension. A particle has no long dimension. Particle composites consist of particles of Particle composites consist of particles of

one material dispersed in a matrix of a one material dispersed in a matrix of a second material. second material.

Generally spherical, ellipsoidal, polyhedral, Generally spherical, ellipsoidal, polyhedral, or irregular in shape. or irregular in shape.

Added to a liquid matrix that later Added to a liquid matrix that later solidifies in some process. solidifies in some process.

The particles may be treated to be made The particles may be treated to be made compatible with the matrix, or they may compatible with the matrix, or they may be incorporated without such treatment. be incorporated without such treatment.

Particles are most often used to extend Particles are most often used to extend the strength or other properties of the strength or other properties of inexpensive materials by the addition of inexpensive materials by the addition of other materials.other materials.

Types of Particle Reinforced Types of Particle Reinforced CompositeComposite

Large ParticleLarge Particle ““LARGE” indicate that particle-matrix interaction LARGE” indicate that particle-matrix interaction

cannot be treated on the atomic or molecular cannot be treated on the atomic or molecular level.level.

Involves large particles that are harder or stiffer Involves large particles that are harder or stiffer than matrix.than matrix.

The reinforcing particles tend to restrain The reinforcing particles tend to restrain movement of the matrix phase in the vicinity of movement of the matrix phase in the vicinity of each particle each particle

The matrix transfer some of the applied stress to The matrix transfer some of the applied stress to the particles, which bear a friction at the load.the particles, which bear a friction at the load.

Bonding at the interface is necessarily important.Bonding at the interface is necessarily important.

Dispersion-strengthenedDispersion-strengthened Small particles (10 to 100 nm)Small particles (10 to 100 nm) Matrix bears most of the applied loadMatrix bears most of the applied load Particles hinder or impede motion of Particles hinder or impede motion of

dislocationsdislocations Plastic deformation is restrictedPlastic deformation is restricted Improves yield and tensile strength.Improves yield and tensile strength. Most of MMCs fall in this categoryMost of MMCs fall in this category Metal, metallic compound, ceramic Metal, metallic compound, ceramic

particle, whisker or etc., is uniformly particle, whisker or etc., is uniformly dispersed in matrix medium.dispersed in matrix medium.

Types of Particle Reinforced Types of Particle Reinforced CompositeComposite

Orientation and GeometryOrientation and Geometry

Approximately in the same Approximately in the same dimension in all direction. dimension in all direction. (Equiaxed).(Equiaxed).

Uniformly distributedUniformly distributed Generally spherical, ellipsoidal, Generally spherical, ellipsoidal,

polyhedral, or irregular in shapepolyhedral, or irregular in shape

Particle and Fiber variablesParticle and Fiber variables For any composite, regardless of the selection of For any composite, regardless of the selection of

matrix and disperse phase (material and type), there matrix and disperse phase (material and type), there are many optionsare many options that will affect properties:that will affect properties:

Each option will impart different benefits to the

final part.

Also surface coatings on the dispersed phase

Large-Particle vs. Dispersion-Strengthened CompositesLarge-Particle vs. Dispersion-Strengthened Composites

Strong Particle>500 nm

Strong Particle<100 nm

Shear

Dislocation stopped

Stress field of dispersion

Dislocation shears through the dispersion

Dispersion Strengthened

Large-Particle

PROCESSPROCESS

Particulate Particulate Reinforcement Reinforcement

ProcessingProcessing The process where the particulate reinforcement The process where the particulate reinforcement

form being formedform being formed Examples of the particulate processing:Examples of the particulate processing:

A. Powder Processing A. Powder Processing

1. Spray drying processing (Liquid) 1. Spray drying processing (Liquid)

2. Vortex Disintegrator Drying (Semi-solid) 2. Vortex Disintegrator Drying (Semi-solid)

3. Fluid Bed and Flash Drying (Moist powder) 3. Fluid Bed and Flash Drying (Moist powder)

4. Microwave Vaccum Drying (Wet powder)4. Microwave Vaccum Drying (Wet powder)

5. Spray Congealing (Liquid melts)5. Spray Congealing (Liquid melts)

B. GranulationB. Granulation1. Spray Drying Granulation Granulation (Liquid)1. Spray Drying Granulation Granulation (Liquid)2. High Shear Granulation – continuous (Powder)2. High Shear Granulation – continuous (Powder)3. Fluid Bed Granulation (Powder)3. Fluid Bed Granulation (Powder)4. High Shear Granulation- Batch (dry 4. High Shear Granulation- Batch (dry

ingredients )ingredients )

C. PelletizingC. Pelletizing1. Layering from Liquids & Powder1. Layering from Liquids & Powder2. Wet & Melts Granulation Pelletizing 2. Wet & Melts Granulation Pelletizing

D. Others ProcessingD. Others Processing1. Pulverized Process1. Pulverized Process2. Particle size reduction through hammer mill2. Particle size reduction through hammer mill3. Particle size reduction through roller mills3. Particle size reduction through roller mills4. Steam Drying of Fibrous Particulates 4. Steam Drying of Fibrous Particulates

E.g.1: Powder – Spray E.g.1: Powder – Spray DryingDrying

From liquid feedsFrom liquid feeds One of the most important One of the most important

continuous drying continuous drying techniques for converting techniques for converting solutions, emulsions, and solutions, emulsions, and slurries into powders.slurries into powders.

The liquid feed is atomized The liquid feed is atomized into droplets which are into droplets which are directed into a controlled directed into a controlled flow of hot air. flow of hot air.

Particles are formed as Particles are formed as moisture evaporates from moisture evaporates from each droplet.each droplet.

Spray Dryer

E.g. 2: Granulation - Spray Drying E.g. 2: Granulation - Spray Drying GranulationGranulation

From liquid feedFrom liquid feed Is a continuous process where Is a continuous process where

the desired mechanism of the desired mechanism of particle growth is layering and particle growth is layering and simultaneous drying of the simultaneous drying of the liquid feed on the surface of the liquid feed on the surface of the smaller granules and nuclei smaller granules and nuclei particles. particles.

Air temperatures are high to Air temperatures are high to achieve the required drying achieve the required drying rates.rates.

High density, free flowing High density, free flowing granules are produced from granules are produced from solution and slurry feeds. solution and slurry feeds.

most suited for inorganic feeds most suited for inorganic feeds Spray Dryer Granulator

E.g. 3: PelletizingE.g. 3: Pelletizing(A)(A)Layering from liquids Layering from liquids A solution or suspension of the active A solution or suspension of the active

component is sprayed onto inert cores component is sprayed onto inert cores consisting of crystals or non-pareil seeds. consisting of crystals or non-pareil seeds.

Is a multi-layer spray coating process Is a multi-layer spray coating process which can be performed in fluid beds, the which can be performed in fluid beds, the Precision Coater™ or the Roto-Precision Coater™ or the Roto-Processor™.Processor™.

Pellet Processor™ Roto-Processor™

E.g. 4: Size Reduction Through Hammer MillE.g. 4: Size Reduction Through Hammer Mill

Hammer millsHammer mills

is a machine whose purpose is to shred material into fine particles is a machine whose purpose is to shred material into fine particles through impact force.through impact force.

essentially a steel drum: contains a vertical or horizontal cross essentially a steel drum: contains a vertical or horizontal cross shaped rotor on which pivoting hammers are mounted.shaped rotor on which pivoting hammers are mounted.

It reduces the particle size of materials by impacting a slow moving It reduces the particle size of materials by impacting a slow moving target with a rapidly moving hammer. target with a rapidly moving hammer.

Particles produced using a hammer mill will generally be spherical Particles produced using a hammer mill will generally be spherical in shape with a surface that appears polished in shape with a surface that appears polished

Rotor

Hopper

Process Description:Process Description:

The rotor is spun at a high speed inside the The rotor is spun at a high speed inside the drum while material is fed into a feed drum while material is fed into a feed hopper hopper Material is impacted by the hammers on the Material is impacted by the hammers on the ends of the rotating cross and thereby is ends of the rotating cross and thereby is shredded and expelled through screens in shredded and expelled through screens in the drum the drum The design and placement of hammers is The design and placement of hammers is determined by operating parameters such as determined by operating parameters such as rotor speed, motor horsepower, and open rotor speed, motor horsepower, and open area in the screen.area in the screen.

E.g. 5: Pulverized ProcessE.g. 5: Pulverized Process

Is the process where material has been Is the process where material has been pounded, crush, or grind to a powder or dust.pounded, crush, or grind to a powder or dust.

Example of process: Pulverization of coalExample of process: Pulverization of coal

Is a method to improve burning efficiency and Is a method to improve burning efficiency and maximize energy outputmaximize energy output

Typically found in power generation, steel and Typically found in power generation, steel and iron manufacturing, cogeneration, cement drying, iron manufacturing, cogeneration, cement drying, and other industries that employ coal injection and other industries that employ coal injection furnaces.furnaces.

Typical pulverizedTypical pulverizedfuel storage and firing systemfuel storage and firing system

DustCollector

Coal fromBunker toPulverizer

To Furnace

StorageBin

Large-particle CLarge-particle Composites omposites ProcessProcess

Processing methods of Processing methods of Large-Large-particleparticle composites compositesPowder Forging ProcessPowder Forging ProcessCalcinations ProcessCalcinations ProcessCold Pressing ProcessCold Pressing ProcessSintering ProcessSintering Process

Powder Forging ProcessPowder Forging Process A powder blank is pressed to a simple A powder blank is pressed to a simple

shape halfway between that of a forging shape halfway between that of a forging billet and the required finished part.billet and the required finished part.

““Preform” is sintered and then hot forged Preform” is sintered and then hot forged to finished size and shape in a closed die. to finished size and shape in a closed die.

The amount of deformation involved is The amount of deformation involved is sufficient to give a final density very sufficient to give a final density very closely approaching that of the solid closely approaching that of the solid metal, and consequently, the mechanical metal, and consequently, the mechanical properties are comparable with those of properties are comparable with those of material forged from wrought bar. material forged from wrought bar.

Calcinations ProcessCalcinations Process Thermal treatment process applied to ores and Thermal treatment process applied to ores and

other solid materials in order to bring about a other solid materials in order to bring about a thermal decomposition, phase transition, or thermal decomposition, phase transition, or removal of a volatile fraction. removal of a volatile fraction.

Normally takes place at temperatures below the Normally takes place at temperatures below the melting point of the product materials. melting point of the product materials.

Calcination is to be distinguished from roasting, in Calcination is to be distinguished from roasting, in which more complex gas-solid reactions take which more complex gas-solid reactions take place between the furnace atmosphere and the place between the furnace atmosphere and the solids.solids.

It is produced by grinding and intimately mixing It is produced by grinding and intimately mixing clay and lime-bearing minerals in the proper clay and lime-bearing minerals in the proper proportions, and then heating the mixture to proportions, and then heating the mixture to about 1400 °C (2550°F) in a rotary kiln.about 1400 °C (2550°F) in a rotary kiln.

Cold Pressing ProcessCold Pressing Process

Bonding operation in which an assembly is Bonding operation in which an assembly is subjected to pressure without the subjected to pressure without the application of heat or drying air until the application of heat or drying air until the adhesive interface has solidified and adhesive interface has solidified and reached proper shear proportions.reached proper shear proportions.

Used in conjunction with a sintering Used in conjunction with a sintering technique to fabricate metal, filament technique to fabricate metal, filament reinforced metal composites having reinforced metal composites having uniaxially reinforced structures.uniaxially reinforced structures.

Sintering ProcessSintering Process

Bonding together of a porous aggregate of Bonding together of a porous aggregate of particles at high temperature. particles at high temperature.

The thermodynamic driving force is the reduction The thermodynamic driving force is the reduction in the specific surface area of the particles. in the specific surface area of the particles.

The mechanism usually involves atomic transport The mechanism usually involves atomic transport over particle surfaces, along grain boundaries and over particle surfaces, along grain boundaries and through the particle interiors.through the particle interiors.

Resulting densification, depending on the Resulting densification, depending on the predominant diffusion pathway. predominant diffusion pathway.

Used in the fabrication of metal and ceramic Used in the fabrication of metal and ceramic components, the agglomeration of ore fines for components, the agglomeration of ore fines for further metallurgical processing and occurs further metallurgical processing and occurs during the formation of sandstones and glaciers.during the formation of sandstones and glaciers.

Dispersion-strengthened Dispersion-strengthened composites Processcomposites Process

Processing methods of dispersion-Processing methods of dispersion-strengthened compositesstrengthened compositesPowder working processPowder working processMechanical alloying processMechanical alloying processHigh pressure casting processHigh pressure casting processMolten metal processMolten metal processSemi-solidification processSemi-solidification process

Powder working processPowder working process

An alloy as a dispersing medium is pulverized and mixed with a An alloy as a dispersing medium is pulverized and mixed with a dispersion strengthening material which is extruded at adispersion strengthening material which is extruded at ahigh temperature under pressure to form a composites material. high temperature under pressure to form a composites material.

Typical powder metallurgy process:

(1) blending of the gas-atomized matrix alloy and reinforcement in powder form

(2) compacting (cold pressing) the homogenous blend to roughly 80% density

(3) degassing the preform to remove volatile contamination, water vapor and gasses

(4) consolidation by vacuum hot pressing or hot isotactic pressing and subsequently extruded, rolled or forged

Mechanical alloying processMechanical alloying processAn alloy as dispersing medium is pulverized and mixed with aAn alloy as dispersing medium is pulverized and mixed with a

dispersion strengthening material, which is mechanicallydispersion strengthening material, which is mechanically

kneaded to form a composite material.kneaded to form a composite material.

Mechanical alloyingMechanical alloying creates alloy without melting but by violently creates alloy without melting but by violently deforming mixtures of different powders. Inert oxides can be introduced deforming mixtures of different powders. Inert oxides can be introduced uniformly into the microstructure. The elemental powders are uniformly into the microstructure. The elemental powders are milledmilled together to produce solid solutions with uniform dispersions of oxide together to produce solid solutions with uniform dispersions of oxide particles. particles.

The dispersion-strengthened alloyed powders are then consolidated using The dispersion-strengthened alloyed powders are then consolidated using hot-isotactic pressing and extrusionhot-isotactic pressing and extrusion to produce a solid with a very fine to produce a solid with a very fine grain structure.grain structure.

Heat treatmentHeat treatment then induces recrystallisation, either into a coarse then induces recrystallisation, either into a coarse columnar grain structure or into a fine, equiaxed set of grains.columnar grain structure or into a fine, equiaxed set of grains.

1

2

3

1 2 3

High pressure casting processHigh pressure casting process

A molten alloy as a dispersing medium is impregnated into a A molten alloy as a dispersing medium is impregnated into a preform ofpreform ofA dispersion strengthening material under pressure and then A dispersion strengthening material under pressure and then solidifiedsolidifiedTo form a composite material.To form a composite material.

Schematic view of a high pressure die casting machine

Molten metal processMolten metal process

A dispersion strengthened material is added to a A dispersion strengthened material is added to a molten alloy as a dispersing medium and then molten alloy as a dispersing medium and then mixed with stirring to form a composite material.mixed with stirring to form a composite material.

Semisolidification processSemisolidification process

An alloy as a dispersing medium is rendered into a An alloy as a dispersing medium is rendered into a mixed solid-liquid mixed solid-liquid phase slurry and added with a dispersion phase slurry and added with a dispersion strengthening material, whichstrengthening material, whichis mixed with stirring to form a composite material. is mixed with stirring to form a composite material.

PROPERTIESPROPERTIES

Mechanical Properties of Mechanical Properties of Particulate ReinforcementParticulate Reinforcement

High specific stiffness, greater strength, High specific stiffness, greater strength, and good fracture properties:and good fracture properties: Influence by the microstructure of the Influence by the microstructure of the

reinforcement; such as size, shape, and spatial reinforcement; such as size, shape, and spatial distribution of the reinforcement.distribution of the reinforcement.

Good corrosion resistance (for MMC)Good corrosion resistance (for MMC) Lead to formation of interface between the Lead to formation of interface between the

matrix reinforcement, interfacial stresses as matrix reinforcement, interfacial stresses as well as high dislocation density in the matrixwell as high dislocation density in the matrix

Advantages of Particulate Advantages of Particulate ReinforcementReinforcement

Less extensive than fibrous reinforcementsLess extensive than fibrous reinforcements Isotropic propertiesIsotropic properties Improves the machinability of the material. Improves the machinability of the material. Compatible with most metalworking process and Compatible with most metalworking process and

often fabricated to near net shapeoften fabricated to near net shape increase the modulus of the matrixincrease the modulus of the matrix decrease the permeability of the matrixdecrease the permeability of the matrix decrease the ductility of the matrix decrease the ductility of the matrix Support higher tensile, compressive and shear Support higher tensile, compressive and shear

stresses. stresses. Ability to tailor the mechanical properties through Ability to tailor the mechanical properties through

selection of reinforcement type and volume fraction selection of reinforcement type and volume fraction along with the metal alloyalong with the metal alloy

APPLICATIONSAPPLICATIONS

Large-particle CompositesLarge-particle Composites Cermets (not Cermets (not cementscements) are ceramic-metal ) are ceramic-metal

compositescomposites Cermented Carbide—cutting toolsCermented Carbide—cutting tools

WC or TiC particles (incredibly hard)WC or TiC particles (incredibly hard) Metal matrix (Co or Ni)Metal matrix (Co or Ni)

The particles will crack under the high stresses in cutting The particles will crack under the high stresses in cutting applications, so the matrix prevents crack propagation applications, so the matrix prevents crack propagation between particles by separating them.between particles by separating them.

Up to 90 volume percent of particles.Up to 90 volume percent of particles. Polymer/Carbon composites includePolymer/Carbon composites include

TiresTires Elastomer matrix with carbon black particles (15-30 vol%).Elastomer matrix with carbon black particles (15-30 vol%). Improved tensile strength, tear and abrasion resistance, and Improved tensile strength, tear and abrasion resistance, and

toughness.toughness. Small particles are optimal, <50 nm.Small particles are optimal, <50 nm.

Ceramic-ceramic composites includeCeramic-ceramic composites include Concrete is: Concrete is:

~70 vol% sand and gravel particles (different sizes ~70 vol% sand and gravel particles (different sizes promotes better packing).promotes better packing).

Portland cement (ceramic/ceramic composite) is the Portland cement (ceramic/ceramic composite) is the binder once water is added.binder once water is added.

Improved tensile, compressive, and shear response Improved tensile, compressive, and shear response by by reinforcingreinforcing with steel rods, bars (rebar), wires, or with steel rods, bars (rebar), wires, or wire mesh (ceramic-ceramic-metal composite).wire mesh (ceramic-ceramic-metal composite). Steel is selected for thermal expansion coefficientSteel is selected for thermal expansion coefficient Not corroded during cement hardeningNot corroded during cement hardening Strong composite/matrix bond is possible, especially if Strong composite/matrix bond is possible, especially if

the steel surface is contouredthe steel surface is contoured Pre stressingPre stressing

Large-particle Reinforced Large-particle Reinforced CompositesComposites

• Examples:Adapted from Fig. 10.10, Callister 6e. (Fig. 10.10 is copyright United States Steel Corporation, 1971.)

Spheroidite steel

matrix: ferrite () (ductile)

particles: cementite (Fe3C) (brittle)

60m

Adapted from Fig. 16.4, Callister 6e. (Fig. 16.4 is courtesy Carboloy Systems, Department, General Electric Company.)

WC/Co cemented carbide

matrix: cobalt (ductile)

particles: WC (brittle, hard)Vm:

10-15vol%! 600m

Adapted from Fig. 16.5, Callister 6e. (Fig. 16.5 is courtesy Goodyear Tire and Rubber Company.)

Automobile tires

matrix: rubber (compliant)

particles: Carbon Black (stiffer)0.75m

Dispersion-strengthening Dispersion-strengthening CompositeComposite Thoria dispersed nickel (Ni with up to 3 vol% Thoria dispersed nickel (Ni with up to 3 vol%

ThOThO22 particles) particles) Sintered aluminum powder (Al matrix with AlSintered aluminum powder (Al matrix with Al22OO33

coated Al flakes)coated Al flakes) Nanometer AlNanometer Al22OO3 3 / Cu composite/ Cu composite Particle aluminum metal matrix composites Particle aluminum metal matrix composites

(PAMMCs)(PAMMCs) Oxides dispersion strengthened (ODS) alloysOxides dispersion strengthened (ODS) alloys

~ austenitic (Ni-based) alloys, which is strengthened by oxide dispersion ~ austenitic (Ni-based) alloys, which is strengthened by oxide dispersion

and by alpha phase precipitatesand by alpha phase precipitates

~ ferritic (Fe-based), strengthened by an oxide dispersion, which are ~ ferritic (Fe-based), strengthened by an oxide dispersion, which are

suitable for gas turbine chambers, high temperature sensors and heaters, suitable for gas turbine chambers, high temperature sensors and heaters,

diesel engine components, and components of advanced energy diesel engine components, and components of advanced energy

conversion systems. conversion systems.

FINISHFINISH