Review on Fabrication Methods of in situ

Metal Matrix CompositesBy:

1. LAW MEI LIN B050810007 4BMFB1

2. MOHD AQHAIRI BIN BAHARI B050810175 4BMFB2

3. MOHAMAD IZZUDIN BIN ABDUL HAMID B050810048 4BMFB1

4. NOOR AYUHAAN BINTI ABD LAH B050910310 4BMFB1

5. RIANAH BINTI JIREN B050910060 4BMFB2

6. SITI SAINILLAH BINTI SULAIMAN B050910279 4BMFB1

7. NADIAH BINTI JAAFAR B050910296 4BMFB1

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What is In Situ?

In situ is a Latin phrase which translates literally to 'In position'.

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What is in situ techniques?

Involve a chemical reaction resulting in the formation of a very fine and

thermodynamically stable reinforcing ceramic phase within a metal matrix.

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Advantages of in situ techniques

1. There is thermodynamic compatibility at the matrix-reinforcement interface.

2. Also, the reinforcement surfaces are likely to be free of contamination.

~ Therefore, stronger matrix- dispersion bond can be

achieved.

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Technologies

1. Powder Metallurgy Method (Fabrication of in situ Fe/TiC)

2. Liquid-Gas Reaction(Fabrication AlN/Al composite)

3. Solid-Gas-Liquid Reaction Method(Formation of fine single crystal TiC platelets in the Al based matrix )

4. In situ – Processed by Ingot Metallurgy(Fabrication of Al-TiC composites)

5. Plasma Metallurgy Method

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In situ – Processed by Ingot Metallurgy

What it means?in which the solidification process where the reinforcing particles are formed in situ in the

molten alloy.

Attractiveness:1.Simplicity2.Economy3.Flexibility

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In situ – Processed by Ingot Metallurgy

1. Tong and Fang (1998) fabricated Al-TiC composites:

• with refined microstructure,

• enhanced dispersion hardening of the reinforcing phases

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Process

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Ingot Metallurgy (Synthesis of composites)Al (99.9%) +

Ti (99.7%)Graphite powder

(40-50 μm)

Heated1100 °C – 1200°C

1h

1300 °C – 1400°C10 minutes

Mixture direct chill cast into ingot bars

Melt in graphite-lined

induction furnace with

argon gas flow.

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Diagram

Example of Ingot Metallurgy10

Rapid solidification(by chill block melt spinning)

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Video(chill block melt spinning)

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Ribbon shape

Chemical Analysis

• The analysis of master ingots was done by the wet method.

• Carbon was determined by using automatic combustion apparatus.

1. Sample is combusted in a stream of oxygen and the carbon of specimen is converted into CO2.

2. The CO2 is fed into a measuring chamber where the concentration peak is detected with nondispersive spectrometer.

3. The linear signal is integrated and displaced digitally after weight compensation and blank correction.

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Stream of

oxygen

Chamber Detection with a

nondispersive spectrometer

AUTOMATIC COMBUSTION APPARATUS

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Applications

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As a general….

IN SITU MMC APPLICATIONS

Rapid Solidification Process Ex : TiC

particulate-reinforced Al

Vapor phase Infiltration

Ex : Silica base aerogel/transition metal composite

Controlled crystallization Ex : magnetic device such

as choke coils & transfomers

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APPLICATIONS OF IN SITU1) AerospaceIn the aerospace industry, equipment on-board aircraft must be tested in situ, or in place, to confirm everything functions properly as a system

2) Petroleum productionIn situ refers to recovery techniques which apply heat or solvents to heavy oil or bitumen reservoirs beneath the earth's crust.

3) Experimental PhysicsIn situ refers to a method of data collection or manipulation of a sample without exposure to an external environment.

4) BiologyIn situ means to examine the phenomenon exactly in place where it occurs (i.e. without moving it to some special medium).

Additional Information

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In-Situ Polymerization

• In-situ polymerization has been used to prepare nanocomposites.

• Inorganic nano-particles are dispersed in monomer, followed by heat or other treatment of the reaction mixture to induce polymerization.

• Advantages of in-situ polymerization technique:

1. Uniform CNT dispersion in monomers

2. Polymer chains grafted onto the convex walls of carbon nanotubes during in-situ; thus CNT homogeneously dispersed in polymer matrix.

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• Advantages: (cont.)

3. Important for the preparation of insoluble and thermally unstable polymer composites, which cannot be processed by solution or melt processing.

4. For preparation of polymer composites with high nanotube loading, in-situ provides very good miscibility with almost any types of polymers.

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• In-situ polymerization methods used to fabricate CNT-PMMA composites by incorporating CNTs during the course of polymerization of MMA.

•Basic starting materials:1. Nanotubes

2. MMA monomer

• Method: In-situ free radical polymerization method involves polymerization of monomer using a radical initiator such as 2.2´-azobisisobutyronitrile (AIBN).

• CNTs are dispersed through ultrasonication in the prepolymer.

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In-Situ Polymerization Processing

• Adding CNT at prepolymer provides good dispersion in the low viscosity of the prepolymer.

• As the polymerization progresses, the viscosity of the solution increases and the polymer grows and wraps around the dispersed CNTs.

• Benefits:

a) Higher interfacial strengths as CNTs interact with the growing polymer, thus forming stronger CNT-polymer bonds via non-covalent or covalent interactions.

b) Composites with enhanced mechanical, electrical and tribological were obtained.

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• For another research of MWCNT-PMMA composites synthesized by in-situ bulk polymerization usig AIBN as free radical initiator, the microstructure are shown in Figure A below.

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Figure A: Microstructure of the in-situ facricated MWCNT-PMMA composite. The bright masses indicates CNTs wrapped with PMMA layers

Q & A

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1. What is the criteria for reinforcement selection?

In general, There are necessary criteria or conditions that must be satisfied for the selection of a ceramic as

reinforcement in the manufacture of good and standard metal matrix composites.

In general, There are necessary criteria or conditions that must be satisfied for the selection of a ceramic as

reinforcement in the manufacture of good and standard metal matrix composites.

Such criteria include density, melting temperature, size and shape, elastic modulus, tensile strength, thermal

stability, compatibility with matrix material, coefficient of thermal expansion, and cost.

Such criteria include density, melting temperature, size and shape, elastic modulus, tensile strength, thermal

stability, compatibility with matrix material, coefficient of thermal expansion, and cost.

2. Why choose Ti and Al for the In-situ processed by Ingot metallurgy?

2. Why choose Ti and Al for the In-situ processed by Ingot metallurgy?

In general, selection of metal or its alloy as matrix for production of MMC depends on the type, required properties and the kind of application where such

composite is required.

In general, selection of metal or its alloy as matrix for production of MMC depends on the type, required properties and the kind of application where such

composite is required.

From this experiment, Al based and Ti based metal matrix composites have a high potential for advanced structural applications when high specific strength as well as good

elevated temperature resistance.

From this experiment, Al based and Ti based metal matrix composites have a high potential for advanced structural applications when high specific strength as well as good

elevated temperature resistance.

3. Why the particulate reinforced MMCs are more interesting due to their ease of fabrication, low costs, and isotropic properties?

Answer : The properties of MMCs are controlled by the size and volume fraction of the reinforcement phase as well by the nature of the matrix reinforcement interface

4. In traditional MMCs, wetting between molten metal and reinforcements is often poor. How this problem can be treated?

Answer : This problem can be treated through a strongly reactive alloying addition, such as Mg and Li and through reinforcement coating.

5) How do we know if MMC is a hybrid composite?

6) What do you have in mind about in situ hybrid composite?

A metal matrix composite (MMC) is composite material with at least two constituent parts, one being a metal. 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.

Scientist do hybrid to pick up good qualities. So there are 2 things better in something they try to mix and make a best item. For e.g. some flower have good looks but no smell and other have great smell but dull look so they mix and try to make a flower with great look and smell together.

The authors suggest that it may name as in situ hybrid composite because:1)It can be achieved in a short processing time2)Many kinds of ceramic powder can be put into alloy liquid