PROCESSING OF ALUMINIUM METAL MATRIX COMPOSITES...

IPASJ International Journal of Mechanical Engineering (IIJME) Web Site: http://www.ipasj.org/IIJME/IIJME.htm

A Publisher for Research Motivation........ Email: [email protected] Volume 2, Issue 12, December 2014 ISSN 2321-6441

Volume 2, Issue 12, December 2014 7

ABSTRACT Composite material is a combination of two or more materials having compositional variations and depicting properties distinctively different from those of the individual materials of the composite. During the past decade, considerable research effort has been directed towards the development of in situ Metal Matrix Composites (MMCs), in which the reinforcements are formed in situ by exothermal reactions between elements or between elements and compounds. Using this approach, MMCs with a wide range of matrix materials (including aluminum, titanium, copper, nickel and iron), and second-phase particles (including borides, carbides, nitrides, oxides and their mixtures) have been produced. In the present work, the elemental TiC powders are mixed with aluminum molten metal to produce the Al-TiC MMC. The proposed investigation is to deal with development of aluminium based composite through casting route. Synthesis, characterization, hardness and tensile strength are proposed to be investigated. By its improved mechanical characteristics the new material is expected to replace existing composites applicable to light weight structural and automotive industries. KEYWORDS: - Composites, Aluminium, Metal Matrix Composites, Stir casting, SEM and XRD

1.INTRODUCTION After iron, Aluminium is now the second most widely used metal in the world. This is because aluminium has a unique combination of attractive properties. Low weight, high strength, superior malleability, easy machining, excellent corrosion resistance and good thermal and electrical conductivity are amongst aluminium’s most important properties. Aluminium is also very easy to recycle. 1.1 COMPOSITE A combination of two or more materials (reinforcing elements, fillers, and composite matrix binder), differing in form or composition on a macro scale. The constituents retain their identities, that is, they do not dissolve or merge completely into one another although they act in concert. Normally, the components can be physically identified and exhibit an interface between one another. Examples are cermets and metal-matrix composites.

Figure 1: Composite Material

PROCESSING OF ALUMINIUM METAL MATRIX COMPOSITES (AMMC)

THROUGH STIR CASTING ROUTE

R.Kumar1. , J.Jegan2, L.Initha3

1, 3. Assistant Professor

2P.G.Scholar, SNS College of Engineering, Coimbatore-641107



Volume 2, Issue 12, December 2014 Page 18

1.2 NEED OF COMPOSITE MATERIAL Composites, compared to metals, have certain unique properties that make them ideal for many applications. Composites to replace traditional materials in industrial, technological and socially relevant applications. Composites can replace metals in areas where they are more efficient and cost-effective. Specialty composites for extreme and special environments. We live in an environment of one bar pressure with an atmospheric temperature of 7 to 45º C. Modern technology has created many extreme environments for which traditional materials are unsuitable. Composites play major roles in creating products for such environments.

2. CLASSIFICATION OF COMPOSITES ON BASIS OF MATRIX MATERIAL

Figure 2: Classification of composites on basis of matrix material

2.1 Metal Matrix Composites (MMC) Metal Matrix Composite are composed of a metallic matrix (aluminum, magnesium, iron, cobalt, copper) and a dispersed ceramic or metallic (lead, tungsten, molybdenum) phase. 2.2 Ceramic Matrix Composites (CMC) Ceramic Matrix Composites are composed of a ceramic matrix and embedded fibers of other ceramic material (dispersed phase). 2.3 Polymer Matrix Composites (PMC) Polymer Matrix Composites are composed of a matrix from thermoset (Unsaturated Polyester (UP), Epoxy (EP) or thermoplastic Polycarbonate (PC), Polyvinylchloride, Nylon Polystyrene) and embedded glass, carbon, steel or Kevlar fibers (dispersed phase).

3.REINFORCEMENT The reinforcement material is embedded into the matrix. The reinforcement does not always serve a purely structural task (reinforcing the compound), but is also used to change physical properties such as wear resistance, friction co-efficient, or thermal conductivity. The reinforcement can be either continuous, or discontinuous. Discontinuous MMCs can be isotropic, and can be worked with standard metalworking techniques, such as extrusion, forging or rolling. In addition, they may be machined using conventional techniques, but commonly would need the use of polycrystalline diamond tooling (PCD).

Figure 3: Model reinforcement process in steel manufacturing




4.PROPERTIES OF ALUMINIUM It has a unique and unbeatable combination of properties that make it into a versatile, highly usable and attractive

construction material. It is light with a density one third that of steel, 2.700 kg/m3. It is strong with a tensile strength of 70 to 700 MPa depending on the alloy and manufacturing process. Extrusions

of the right alloy and design are as strong as structural steel. The Young’s modulus for aluminium is a third that of steel (E =70,000 MPa). This means that the moment of

inertia has to be three times as great for an aluminium extrusion to achieve the same deflection as a steel profile. It has a good formability, a characteristic that is used to the full in extruding. Aluminium can also be cast, drawn

and milled. It is very easy to machine. Ordinary machining equipment can be used such as saws and drills. Aluminium is also

suitable for forming in both the hot and the cold condition. It can be joined using all the normal methods available such as welding, soldering, adhesive bonding and riveting. A thin layer of Oxide is formed in contact with air, which provides very good protection against corrosion even in

corrosive environments. This layer can be further strengthened by surface treatments such as anodizing. The thermal and electrical conductivities are very good even when compared with copper. Furthermore, an

aluminium conductor has only half the weight of an equivalent copper conductor. It has a relatively high coefficient of linear expansion compared to other metals. This should be taken into account

at the design stage to compensate for differences in expansion. It is not poisonous and is therefore highly suitable for the preparation and storage of food. It is a good reflector of both light and heat.

4.1 APPLICATION AND USE OF ALUMINIUM Aluminum in Buildings Aluminum is used in windows and doors: besides windows and doors , also curtain walls, frames, shutters, false

windows, insect screens, verandas, handrails, fencing, gates, eaves, sun breakers, sun blinds, Venetian blinds, prefabricated buildings, radiators and heat exchangers, metal sheeting for false ceilings, solar panels, roofing, etc.

Aluminium in Transport Its high strength/weight ratio, aluminium is used in the manufacture of engines, pumps, pistons, wheels,

connecting rods, hubs, valves, frames and trimmings, bumpers, truck sides, fans, parts for bodywork, radiators and heat exchangers. The transport sector is one of the major aluminium users, equal to about one third of all the metal consumed in Europe. One of the main reasons is that it costs to move a weight.

Aluminium in Production engineering Aluminium is used in the manufacture of machines and equipment. Printing machines, textile machines,

woodworking machines, office equipment and computers, scientific instruments. Aluminium in Electronics Aluminium is the chief material competing with copper, thanks to its very good electrical conductivity. The most

widely recognized application is that of overhead electricity distribution lines, almost all based on aluminium cables.

Aluminium in the Household Aluminium is used in many household products: cooking utensils, electrical household appliances, ladders, shower

screens, furnishing, lighting fixtures, furniture components, equipment for sports and leisure. There are really only a few application sectors where aluminium is not used. Use is expected to grow as its

properties are especially appreciated by designers, architects and engineers as well as by the manufacturers and end users of the product. Moreover the environmental impact of aluminium is very favorable. None of its production processes involves significant risks for health or the environment. In fact the aluminium industry has been much concerned over the years to reduce pollution and the effects on the environment.




Figure 4: Application and use of aluminium

5.STIR CASTING

In a stir casting process, the reinforcing phases are distributed into molten matrix by mechanical stirrer. Stir casting of metal matrix composites was initiated in 1968, when S. Ray introduced alumina particles into aluminium melt by stirring molten aluminum alloys containing the ceramic powders. Mechanical stirring in the furnace is a key element of this process. The resultant molten alloy, with ceramic particles, can then be used for die casting, permanent mold casting, or sand casting. Stir casting is suitable for manufacturing composites with up to 30% volume fractions of reinforcement. The cast composites are sometimes further extruded to reduce porosity, refine the microstructure, and homogenize the distribution of the reinforcement. A major concern associated with the stir casting process is the segregation of reinforcing particles which is caused by the surfacing or settling of the reinforcement particles during the melting and casting processes. The final distribution of the particles in the solid depends on material properties and process parameters such as the wet condition of the particles with the melt, strength of mixing, relative density, and rate of solidification .The distribution of the particles in the molten matrix depends on the geometry of the mechanical stirrer, stirring parameters, placement of the mechanical stirrer in the melt, melting temperature, and the characteristics of the particles added. An interesting recent development in stir casting is a two-step mixing process. In this process, the matrix material is heated to above its liquids temperature so that the metal is totally melted. The melt is then cooled down to a temperature between the liquids and solidus points and kept in a semi-solid state. At this stage, the preheated particles are added and mixed. The slurry is again heated to a fully liquid state and mixed thoroughly. This two-step mixing process has been used in the fabrication of aluminum metal matrix composite. Among all the well-established metal matrix composite fabrication methods, stir casting is the most economical. For that reason, stir casting is currently the most popular commercial method of producing aluminum based composites.

Fig 5:Stir casting




6.X-RAY DEFRACTİON ANALYSIS

X-rays are electromagnetic radiation of wavelength about 1 Å (10-10 m), which is about the same size as an atom. They occur in that portion of the electromagnetic spectrum between gamma-rays and the ultraviolet. The discovery of X-rays in 1895 enabled scientists to probe crystalline structure at the atomic level. X-ray diffraction has been in use in two main areas, for the fingerprint characterization of crystalline materials and the determination of their structure. Each crystalline solid has its unique characteristic X-ray powder pattern which may be used as a "fingerprint" for its identification. Once the material has been identified, X-ray crystallography may be used to determine its structure, i.e. how the atoms pack together in the crystalline state and what the interatomic distance and angle are etc. X-ray diffraction is one of the most important characterization tools used in solid state chemistry and materials science.

Figure 6: XRD analysis for Al+5%TiC Composite

6.1 APPLICATIONS OF XRD

XRD is a nondestructive technique.

To identify crystalline phases and orientation.

To determine structural properties.

Lattice parameters, strain, grain size, expitaxy, phase composition, preferred orientation order – disorder transformation, thermal expansion.

To measure thickness of thin films and multilayer’s.

To determine atomic arrangement.

7.SEM ANALYSIS Scanning Electron Microscope (SEM), type of electron microscope, designed for directly studying the surfaces of solid objects that utilizes a beam of focused electrons of relatively low energy as an electron probe that is scanned in a regular manner over the specimen. The signals that derive from electron-sample interactions reveal information about the sample including external morphology (texture), chemical composition, and crystalline structure and orientation of materials making up the sample. Areas ranging from approximately 1 cm to 5 microns in width can be imaged in a scanning mode using conventional SEM techniques (magnification ranging from 20X to approximately 30,000X, spatial resolution of 50 to 100 nm). The design and function of the SEM is very similar to the EPMA and considerable overlap in capabilities exists between the two instruments. 7.1 PRINCIPLES OF SEM Accelerated electrons in an SEM carry significant amounts of kinetic energy, and this energy is dissipated as a variety of signals produced by electron-sample interactions when the incident electrons are decelerated in the solid sample. These signals include secondary electrons (that produce SEM images), backscattered electrons (BSE), diffracted backscattered electrons (EBSD that are used to determine crystal structures and orientations of minerals), photons




(characteristic X-rays that are used for elemental analysis and continuum X-rays), visible light (cathodoluminescence--CL), and heat. As the excited electrons return to lower energy states, they yield X-rays that are of a fixed wavelength (that is related to the difference in energy levels of electrons in different shells for a given element). Thus, characteristic X-rays are produced for each element in a mineral that is "excited" by the electron beam. SEM analysis is considered to be "non-destructive"; that is, x-rays generated by electron interactions do not lead to volume loss of the sample, so it is possible to analyze the same materials repeatedly

Figure 7: Morphology of Al+5%TiC composite

Figure 8: Morphology of Al+10%TiC composite

8.TENSILE TEST PROCEDURE Select the suitable dimension of tensile specimen for each standard. The allotted test bar to be machined turned appropriately. Centre of the test specimen bar has to be marked and initial diameter (d1) has to be measured. Marking to be made on the either side of the centre in accordance with standard & initial length (L1) has to be measured. Record the identify number, Serial no and measured dimension. Hold the test specimen bar in jaws of the universal testing machine. Close the inlet / outlet valves and switch on the machine. Apply the load slowly by opening the inlet valve. Note down the load when the pointer needle deflects (yield load –YL). Start increasing the load by opening the inlet valve. Note down the load when the bar breaks (ultimate tensile load – UTL). The final diameter (d2) and final length (L2) are measured by joining the two broken specimen. Calculate the yield & ultimate strength and record the same in Mechanical Observation. 8.1 TENSILE TEST RESULTS The following table 1 shows the tensile test results on various composites




Table 1:Tensile Test Results S.NO COMPOSITES MAX

STRESS (0.2) N/mm2

MAX STRESS N/mm2

ELONGATION In mm

1 A1 175 245 16 2 A1+5%TiC

182 242 11

3 A1+10%TiC 210 258 7

Figure 9: Tensile Stress versus (Al+0%TiC, Al+5%TiC & Al+10%TiC) composites

Figure 10: Elongation versus Weight % of TiC (Al+0%TiC, Al+5%TiC & Al+10%TiC)

Figure 11: Compressive strength versus wt. % of TiC (Al+0%TiC, Al+5%TiC & Al+10%TiC)

9.HARDNESS TEST PROCEDURE Brinell hardness tests: The diameter of the hardened steel or tungsten carbide indenter is 10 mm. Applied Loads= 500-3000 kg.The diameter of resulting indentation on the surface is measured using a special low power microscope. the measurement is converted to hardness number.




Figure 12: Properties of prepared metal matrix composites

10.ROCKWELL HARDNESS TEST THE FOLLOWING TABLE 2 SHOWS THE ROCKWELL HARDNESS TEST ON VARIOUS COMPOSITES. D: 16×25.4=1.5875mm

Table 2: Rockwell Hardness Test

S.NO COMPOSITES HARDNESS 1 A1 26 2 A1+5%TiC 34 3 A1+10%TiC 42

Figure 13: Hardness versus composites (Al+0%TiC, Al+5%TiC & Al+10%TiC)

11.CONCLUSION The processing of stir casting route is done with TiC powders and are mixed with Aluminium molten metal to produce the Al-TiC. The Mechanical properties of Al-TiC such as Tensile strength, Hardness, Compressive strength are studied.

REFERENCES [1] Akdogan, A.Ozben, T., 2001. Investigation of the mechanical properties of produced squeeze casting melted with

SiC-P reinforced metal matrix composite materials. In; proceeding of the 2nd mechanical engineering materials and manufacturing technologies symposium Turkey, pp: 358-367.

[2] A.R chambers and S.E Stephens, machining of Al-5mg reinforced with 5 vol % saffil and 15 vol % SiC. Journal of materials science and engineering A 135 (1991) 2878.

[3] M.J. McGinty and C.W Preuss, machining ceramics fiber metal matrix composites. Proc. High productivity machining materials and processes. USA, 1985 pp. 231-242.

[4] M.C. Shaw, Metal cutting principles, Clarendon Oxford, 1984. [5] A.R. Chambers, the machinability of light alloy MMCs, composites: part A (1996) 143-147.ssss [6] Troegercp, Starke EA, Micro structural and mechanical characterization of a super plastic 6XXX aluminium alloy,

Mater SciEng A 2000; 277; 102-113. [7] Ricci W.S., machining Metal Matrix Composites, MR87-827, SME Technical paper, 1987.




[8] Lane, c., the effect of different reinforcements on PCD tool life for aluminium composites. In machining of composites materials. Ed T.S. Srivatsan and D.M. Barden. ASM International, Materials Park. Ohio, 1992 pp: 17-27.

[9] P.Rohatgi Advanced in cast MMCs, Adv. Material process. 2 (1990). 38-44. [10] Rajeshkumar Gangaram Bhandare, Parshuram M.Sonawane, Preparation of Aluminium Matrix Composite by Stir

casting method,IJEAT,Volume-3,Issue-2.

AUTHORS

R. KUMAR completed his degree in B.E Mechanical Engineering from Alagappa Chettiyar College of Engineering, Karaikudi, Tamilnadu and M.E Manufacturing Engineering from Chendhuran College of Engineering and Technology, Pudukkottai, Tamilnadu.His Teaching Experience is 9.5 years. And now he is working as a Assistant Professor in SNS College of Engineering, Saravanampatti, Coimbatore, Tamilnadu.

J. JEGAN completed his degree in B.E Mechanical Engineering (Manufacturing) from Annamalai University, Chidambaram, Tamilnadu. And, now he is pursuing his M.E Manufacturing Engineering in SNS College of Engineering, Saravanampatti, Coimbatore, Tamilnadu. L. INITHA completed her degree in B.E Mechanical Engineering from Government College of Engineering, Tirunelveli, Tamilnadu and M.E Industrial Engineering from P.S.G College of Technology, Coimbatore Tamilnadu. Her Teaching Experience is 13 years. And now she is working as a Assistant Professor in SNS College of Engineering, Saravanampatti, Coimbatore, Tamilnadu.

PROCESSING OF ALUMINIUM METAL MATRIX COMPOSITES...

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