ammcs using stir casting

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Kandpal, et al., International Journal of Advanced Engineering Technology E-ISSN 0976-3945

Int J Adv Engg Tech/IV/III/July-Sept.,2013/26-29

Research PaperMANUFACTURING OF AMMCS USING STIR CASTING

PROCESS AND TESTING ITS MECHANICAL PROPERTIESAjay Singh, Love Kumar, Mohit Chaudhary, Om Narayan, PallavSharma, Piyush

Singh, *Bhaskar Chandra Kandpal, Som Ashutosh Address for Correspondence

Department of Mechanical Engineering, Inderprastha Engineering College, Ghaziabad, Uttar Pradesh

ABSTRACTAluminum alloys are widely used in aerospace and automobile industries due to their low density and good mechanical

properties, better corrosion resistance and wear, low thermal coefficient of expansion as compared to conventional metalsand alloys. The excellent mechanical properties of these materials and relatively low production cost make them a veryattractive candidate for a variety of applications both from scientific and technological viewpoints. The aim involved indesigning aluminum based metal matrix composite materials is to combine the desirable attributes of metals and Ceramics.Present work is focused on the study of behavior of Aluminum Cast Alloy (6063) with alumina (Al 2O3) composite produced

by the stir casting technique. Different % age of alumina powder is used as reinforcement phase in this AMMC. Variousmechanical tests like tensile test, Hardness Test, Impact test are performed on the samples of AMMC to evaluate themechanical properties of this aluminum based metal matrix composite.KEYWORDS- composite, alumina (Al 2O3), metal matrix composite (MMC), aluminum metal matrix composite (AMMC)

1. INTRODUCTIONThe aim involved in designing metal matrixcomposite materials is to combine the desirableattributes of metals and ceramics. The addition ofhigh strength, high modulus refractory particles to aductile metal matrix produce a material whosemechanical properties are intermediate between thematrix alloy and the ceramic reinforcement.Aluminium metal matrix composite (AMMCs) referto the class of light weight high performancealuminium centric material systems. Thereinforcement in AMMCs could be in the form ofcontinuous/discontinuous fibres, whisker or

particulates, in volume fractions ranging from a few percent to 70%. Properties of AMMCs can be tailoredto the demands of different industrial applications bysuitable combination of matrix, reinforcement and

processing routes. There are various types of AMMCslike Al/SiC, Al/ Al 2O3, Al. TiC, etc. which arecommonly used in automotive and defense. TheseAMMCs have greater demand because of theiradvanced properties like greater strength, improvedstiffness, reduced density, improved high temperature

properties, controlled thermal expansion coefficient,enhanced and tailored electrical properties, improvedabrasion and wear resistance, control of mass,improved damping capabilities.1.1. Processing of MMCSAccordingly to the temperature of the metallic matrixduring processing the fabrication of MMCs can beclassified into three categories: (a)Liquid phase

processes, (b) solid state processes, and (c) Two phase (solid-liquid) processesStir Casting Process -Stir Casting is a liquid statemethod of composite materials fabrication, in which adispersed phase (ceramic particles, short fibers) ismixed with a molten matrix metal by means ofmechanical stirring. The liquid composite material isthen cast by conventional casting methods and mayalso be processed by conventional Metal formingtechnologies. The Stir Casting set up is shown inFigure 1.1.2 Literature review related to MMC and AMMCThe main concept of composite is that it containsmatrix materials. In composite material thereinforcements can be fibers, particulates or whiskers,and the matrix materials can be metals, plastics, orceramics. The reinforcements can be made from

polymers, ceramics and metals. [1].

Fig.1- Stir casting (1)Some automotive companies using MMC for disc

brakes also. Honda Company used AMMC forcylinder liners in some of their engines like F20C,F22C and H22A. In recent years considerabledevelopment has occurred in nonferrous compositesand attention is now being given to make iron basedcomposites. The paper [2] reviews the ongoing

research and interaction between iron based materialsand reinforcements including wetting and spreadingof iron melts on ceramic materials. The paper

provides insight into the evolution of the processesthat are used to manufacture iron based composites,and the applications that benefit from their uniquecharacteristics. In order for ferrous based compositematerials to find applications in productionenvironments, consistent and controlled mechanicaland physical characteristics are required. Ultimately,industry standards need to be written defining thematerial design parameters. Over the past thirty yearsMetal Matrix Composites (MMCs) have [3] emerged

as an important class of material within theengineering industry. At present, MMCs offerattractive performance or weight-saving alternativesfor a wide range of applications within the sportindustry, from Formula 1 racing components to golfclub shafts. This paper briefly reviews the advantagesof MMCs, and presents a study of the effects ofadditional treatments (heat and surface) which

produce beneficial characteristics in monolithic andalloy materials, but whose effects become morecomplex when applied to composites. The materialused for this study was 2124 Al alloy matrix,reinforced with particulate silicon carbide having amean particle size of around 3 µm treatment. Theinfluence of machining parameters [4] such as cuttingforces and surface roughness on the machinability ofLM6/ SiCp metal matrix composites at differentweight fraction of SiCp discussed in this paper. It isobserved that the depth of cut and the cutting speed at

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constant feed rate affects the surface roughness andthe cutting forces during dry turning operation of castMMCs. It is also observed that higher weight

percentage of SiCp reinforcement imparts a highersurface roughness and needs high cutting forces. Thisexperimental analysis and test results on themachinability of Al/SiC-MMC will provide essentialguidelines to the manufacturers. A detailed study [5]on the processing of Al-metal matrix composites cites

with the reinforcement of different particulates suchas SiC, TiN and TiO 2 was carried out. The results ofthe present studies show that the Al based composites

prepared through various techniques exhibitsexcellent mechanical, physical and tribological

properties and could emerge as promising materialsfor defense, aerospace and other engineeringapplications. With concern [6] increasing overenvironmental issues, reduction in automobile weighthas become more important and has been proved to

be effective for improving fuel efficiency. MetalMatrix Composites (MMC) are expected to be usefulto cope with these problems. The authors havedeveloped a new aluminium engine block which hasthe cylinder bore surface structure reinforced withshort hybrid fibres of alumina and carbon. Thedevelopment of aluminum metal matrix composites(Al-MMC) brake rotor and pad was discussed [7].Theimprovement in fuel consumption rate requires areduction in vehicle weight. In this study, wedeveloped aluminum metal matrix composites brakerotor and pads, which have equivalent braking effectsand wear resistance to those of the conventional castiron rotor, by optimization of the quantities and the

particle diameter ratio of hard particles used for the

rotor and the pad. Metal matrix composites [8] offerconsiderable potential for widespread application inmost aerospace fields. The potential for the use ofthese materials in civil aircraft is largely dependent oncosts and currently these are too high. However, bythe use of appropriate design and manufacturingtechnology this intrinsic high cost can be overcome tounlock their potential 1.3 Alumina as reinforcementAluminum oxide, commonly referred to as alumina,

possesses strong ionic inter atomic bonding givingrise to its desirable material characteristics. It canexist in several crystalline phases which all revert to

the most stable hexagonal alpha phase at elevatedtemperatures. Its high hardness, excellent dielectric

properties, refractoriness and good thermal properties make it the material of choice for a widerange of applications.1.4 Effect of particle sizeThe deformation and fracture behavior of thecomposite revealed the importance of particle size. Areduction in particle size is observed to increase the

proportional limit, yield stress and the ultimate tensilestress. It is well established that large particles aredetrimental to fracture toughness due to theirtendency towards fracture. It would be highlydesirable to have a composite system where thereinforcing particles are relatively fine (4µm or less)so as to get the stiffness benefits of a compositewithout significantly lowering fracture toughness. 1.5 Effect of reinforcement distribution

Apart from the reinforcement level, thereinforcement distribution also influences theductility and fracture toughness of the MMC andhence indirectly the strength. A uniformreinforcement distribution is essential for effectiveutilization of the load carrying capacity of thereinforcement. Non-uniform distributions ofreinforcement in the early stages of processing wasobserved to persist to the final product in the forms of

streaks or clusters of uninfiltrated reinforcement withtheir attendant porosity, all of which loweredductility, strength and toughness of the material. 2. EXPERIENTIAL PROCEDURE2.1 Preparation of aluminum based metal matrixcomposite (AMMC)The most important aspects of the microstructure isthe distribution of the reinforcing particles, and thisdepends on the processing and fabrication routesinvolved. The oxides of reinforcing particles used inthe composites have a varying density. Density ofthe particles is one of the important factorsdetermining the distribution of the particles inmolten metal. Particles having higher density thanmolten metal can settle at the bottom of the bathslowly and particles of lower density can segregateat the top. During subsequent pouring of thecomposite melt, the particle content may vary fromone casting to another or even it can vary in the samecasting from one region to another. Thereforeuniform distribution of the particles in the melt is anecessary condition for uniform distribution of

particles in the castings. The properties ofcomposites are finally dependent on the distributionof the particles. Hence the study of the distribution

of the particles in the composite is of greatsignificance. Aluminum Alloy 6061 was melted in acrucible by heating it in a muffle furnace at 800°Cfor three to four hours. The Alumina particles were

preheated at 1000 ºC and 900 oC respectively for oneto three hours to make their surfaces oxidized. Thefurnace temperature was first raised above theliquidus temperature of Aluminum near about 750 ºCto melt the Al alloy completely and was then cooleddown just below the liquidus to keep the slurry inSemi solid state. Automatic stirring was carried outwith the help of radial drilling machine for about 10minutes at stirring rate of 290 RPM. At this stage,the preheated Alumina particles were addedmanually to the vortex. In the final mixing processesthe furnace temperature was controlled within 700 ±10ºC. After stirring process the mixture was pour inthe other mould to get desired shape of specimen asshown in Figure. The presence of reinforcementthroughout the specimen was inspected by cuttingthe casting at different locations and undermicroscopic examination. Same process was used forspecimens with different compositions of Alumina.Compositions of samples are shown in Table 1:

Table 1- Compositions of samplesS.No

Sample composition(%of alumina in

ammc)

Aluminiumalloy 6063( grams)

Aluminiumoxide

( grams)1 2.5 1950 502 5 1900 1003 7.5 1850 1504 10 1800 200

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2.2 Preparation of Patterns design aIn this step we have prepared patters

various mechanical tests.

Fig.2 -Pattern Drawing of various test

Fig 3- Torsionpattern

Fig 4 -Fatatter

Fig 5- Tensile pattern

2.3 Mould Making ProcessIn this step we have prepared moulspecimen of various mechanical teststest, hardness test, torsion test, etc.

Fig 6- Mould Making2.4 Casting ProcessIn this step we have first prepared alucomposite material in the open heardiscussed in above section to castvarious mechanical tests.

ional Journal of Advanced Engineering Technology

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d patternof wood for

specimens

gue

for castinglike tensile

minum basedh furnace asspecimens of

Fig 7- Casting

2.5 Casted samples of aluminumatrix composite

Fig8 - Sample of impact

Fig9 - Sample of fatigue2.6 Mechanical testing of casted AAfter casting samples of various meAMMC material, following mechcarried out to check the check

properties of composite material.done on various mechanical testinuniversal testing machine, Vickersmachine, impact testing machine assection. 2.6.1 Impact Test The Charpy impact test, also knowV-notch test, is a standardized highwhich determines the amount of enea material during fracture. This absomeasure of a given material's toughn

Fig.10 – Impact testing machWith the increase in Al2O3 constrength is increases w.r.t. base met

proper dispersion of Al2O3 into theinterfacial bonding in between theAlumina interfaces.2.6.2 Hardness test A Vicker hardness tester machinhardness measurement of composite

Fig 11. – Vickers testing

-ISSN 0976-3945

m based metal

test

testMC

chanical test ofnical tests arehe mechanicalhese tests aremachines like

ardness testingiscussed in this

as the Charpystrain- rate test

rgy absorbed byrbed energy is aess.

ine (10) stituent Impactl. This is due tomatrix or strongAl alloy 6063&

e used for thematerial.

(10)

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Kandpal, et al., International Journal of Advanced Engineering Technology E-ISSN 0976-3945

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The results predict that uniform increase in hardnessis also seen. This is due to increase in resistance todeformation by adding Alumina as reinforcement in6063 alloy.2.6.3 Tensile test Tensile tests were used to assess the mechanical

behavior of the composites and matrix alloy.The composite and matrix alloy rods were machinedto tensile specimens with a diameter of 6mm and

gauge length of 30 mm. As the reinforcement wt. %increases, UTS is also increases. This happens may be due to dispersion of Alumina which createshindrance to dislocation motion. This may resultsincrease in tensile strength of reinforced Al 6063alloy.All these mechanical tests are done properly as perthe standards given in various material testing books.For these tests we observed improved in mechanical

properties of newly manufactured AMMC materialusing stir casting as compared to aluminum alloy6063 and aluminum oxide.

Figure12 – Universal testing machine (10)CONCLUSION The conclusions drawn from the presentinvestigation are as follows:

• The results confirmed that stir formed Al alloy6063 with Al2O3 reinforced composites isclearly superior to base Al alloy 6063 in thecomparison of tensile strength, Impact strengthas well as Hardness.

• Dispersion of Al2O3 particles in aluminummatrix improves the hardness of the matrixmaterial.

• It is found that elongation tends to decreasewith increasing particles wt. percentage, whichconfirms that alumina addition increases

brittleness.• Aluminum matrix composites have been

successfully fabricated by stir castingtechnique with fairly uniform distribution ofAl2O3 particles.

• It appears from this study that UTS and Yieldstrength trend starts increases with increase inweight percentage of Al2O3 in the matrix.

ACKNOWLEDGEMENTSThe authors would like to acknowledge the supportof, in particularly Department of MechanicalEngineering, Inderprastha Engineering College,Ghaziabad, U.P funding the current research in thisarea.REFERENCES

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