STUDIES ON CHARACTERIZATION OF AL 6061/ MOS 2 · PDF fileCh.V.S.ParameswaraRao Professor,...

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International Journal of Mechanical Engineering and Technology (IJMET) Volume 8, Issue 8, August 2017, pp. 998–1003, Article ID: IJMET_08_08_108

Available online at http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=8&IType=8

ISSN Print: 0976-6340 and ISSN Online: 0976-6359

© IAEME Publication Scopus Indexed

STUDIES ON CHARACTERIZATION OF AL

6061/ MOS2 METAL MATRIX COMPOSITE

M. Geeta Rani

Research Scholar, Department of Mechanical Engineering, K L University,

Vijayawada, Andhra Pradesh, India

Ch.V.S.ParameswaraRao

Professor, Department of Mechanical Engineering, Narayana Engineering College,

Guduru, Andhra Pradesh, India

K .Rama Kotaiah

Professor, Department of Mechanical Engineering, KKR & KSR Institute of Technology and

Sciences, Vinjanampadu, Guntur, Andhra Pradesh, India

ABSTRACT

The investigations on the characterization of Al 6061 base metal matrix composite

(MMC) reinforced with Molybdenum disulphide (MoS2) samples are reported in this

paper. Aluminium MMC prepared with MoS2 powder of particle size of less than 2µm,

with weight ratios of 1, 2, 3, 4, 5 & 5.5 %. These composites were prepared by using

stir casting technique. A series of tests were conducted to evaluate mechanical

properties such as tensile strength, yield strength, impact strength and hardness for

the specimen. The results were compared with base alloy. The results are revealing

that the hardness and tensile strength increased with increase in wt. % of

reinforcement particles in the matrix up to 4% and the hardness and tensile strength

decreased for 5 % , 5.5% addition of reinforcement in the matrix. Investigations show

that the MMC with 4% of MoS2 have better mechanical properties i.e. hardness and

tensile strength yield strength.

Keywords: Al-6061, Mechanical properties, MMC, MoS2 powder, Stir casting

Cite this Article: M. Geeta Rani, Ch.V.S.ParameswaraRao and K .Rama Kotaiah,

Studies on Characterization of Al 6061/ Mos2 Metal Matrix Composite, International

Journal of Mechanical Engineering and Technology 8(8), 2017, pp. 998–1003.

http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=8&IType=8

1. INTRODUCTION

In the last two decades, research has shifted to composite materials to meet the global

demands. This led to the concept of combining different materials. Metal matrix composites

(MMCs) are increasingly becoming attractive materials for advanced aerospace applications

Studies on Characterization of Al 6061/ Mos2 Metal Matrix Composite


because their properties can be tailored through the addition of selected reinforcements [1-2].

Composite material is a material composed of two or more distinct phases are

combined. MMC is prepared with the help of introducing reinforcement

particles in the matrix of any metal. These particles increases the properties like abrasive

wear resistance, hardness, strength to weight ratio, stiffness and many thermal properties. [3].

The commonly used metallic matrices include Al, Mg, Ti, Cu, Si and their alloys. These

alloys are preferred matrix materials for the production of MMCs. The reinforcements being

used are fibers, whiskers, and particulates [4].

In the present investigation Aluminium 6061 alloy was used as the matrix material.

Among the various Aluminium alloys, Aluminium 6061 alloy is typically characterized by

properties such as fluidity, corrosion resistance, cast ability, and high strength-weight ratio.

[5]. Due these good properties Al 6061 is used in construction of aircraft structures, such as

wings and fuselages and SCUBA tanks.

The chemical composition of Al6061 is shown in Table 1.

Table 1 Chemical Composition of Al 6061

Component Si Mg Fe Cu Cr Mn Ti Zn Al

Weight % 0.679 0.309 0.218 0.183 0.094 0.041 0.047 0.048 Balance

2. EXPERIMENTATION

2.1 Molybdenum Disulfide Reinforcement

MoS2 is a new graphene which is having attractive layered structure. It is very strong and light

weight. It gained interest in the scientific community as a potential replacement for silicon.

2.2 Preparation of the metal matrix composite:

Al-6061 was used as the matrix and molybdenum disulphide (MoS2) as reinforcement. The

metal matrix composites were prepared using stir casting technique (fig.1), by varying the

MoS2 in wt.% of 1%, 2%, 3%, 4%, 5% and 5.5% of 2µm particle size.

Figure 1 Molten metal in the furnace

Appropriately estimated amount of Aluminium alloy was fed into the electric furnace and

was melted at 700o c. An appropriate amount of (1% of the wt. of base metal) MoS2 particles

were added slowly to the molten Aluminium metal.

The MoS2 powder was pre-heated up to 500o c to remove the moisture (if any) and then it

was added to the molten metal. The stirring process takes place at a speed of 300 rpm with a

M. Geeta Rani, Ch.V.S.ParameswaraRao and K .Rama Kotaiah


stirrer. Then the mixture is transferred to a die casting mould to get the required specimens

shown in fig.4. The same procedure was followed to get the MMCs of other wt. % i.e. 2 %, 3

%, 4 %, 5% and 5.5%

2.3 Testing of the Material

The specimens were tested for their mechanical properties i.e. tensile strength, Impact

strength and hardness and also tested for electrical conductivity for 4% MMC

2.3.1. Hardness Test

The hardness test was carried out on the base metal and metal matrix samples by using Brinell

Hardness Testing Machine.

2.3.2. Impact Test

The specimens were subjected to Charpy impact test to measure the impact strength.

(figure 2)

Figure 2 1% MoS2 2% MoS2 3% MoS2 4% MoS2 5% MoS2

2.3.3. Tensile Testing

Test was carried out on a computerized UTM. The tested specimens were shown in fig.3

Figure 3 Al 6061/ MoS2 MMC tested specimens

3. RESULTS AND DISCUSSIONS

3.1 Microstructure

The microstructure of the specimen was observed by using computerized microscope. The

structures were shown in Fig.4 for different compositions of MoS2.

Microstructure studies clearly reveal that the distribution of MoS2 in the matrix in fig 4(a),

4(b) is poor. It is observed from the fig 4(c) and 4(e), the reinforced particles are in the form

of small lumps. Figure 4 (d) clearly reveal that there is fairly uniform distribution of MoS2

throughout the MMC. From the microstructures it is observed that Al 6061 is able to dissolve

MoS2 particles up to 4% with effectively. There after by increasing the wt % Al 6061 is

having less capability of dissolving the MoS2



Figure 4 (a) MMC with 1% MoS2 under 100X (b) MMC with 2% MoS2 under 100X

(c) MMC with 3% MoS2 with 100X (d) MMC with 4 % MoS2with 100X

(e) MMC with 5 % MoS2 with 100X

4.2 Tensile strength:

The tests revealed that, the ultimate tensile strength gradually increased by the increase in wt

% of the reinforcement added to the metal matrix. The maximum tensile strength of 96.7

N/mm2

was observed at 4 % MoS2. The increasing trend of ultimate tensile strength is shown

in figure 5.

Al 6061 1 %MoS2 2 % MoS2 3 % MoS2 4 % MoS2 5 % MoS25.5 % MoS2

0

20

40

60

80

100

Ten

sile

Str

eng

th (

N / m

m2)

Material

Al 6061 1 % MoS2 2 % MoS2 3 % MoS2 4 % MoS2 5 % MoS2 5.5 % MoS2

0

10

20

30

40

50

60

70

80

Yie

ld S

treng

th

Material

Figure 5 Tensile strength of MMC Figure 6 Tensile Yield strength of MMC

M. Geeta Rani, Ch.V.S.ParameswaraRao and K .Rama Kotaiah


Al 6061 1 % MoS2 2 % MoS2 3 % MoS2 4 % MoS2 5 % MoS2 5.5 % MoS2

0

10

20

30

40

50

60

Impact S

tren

gth

(N

/ m

m2)

Material

Al 6061 1% MoS2 2% MoS2 3% MoS2 4% MoS2 5% MoS25.5% MoS2

0

5

10

15

20

25

30

Hard

ness

Material

Figure 7 Impact strength of MMC Figure 8 Hardness of MMC

4.3 Tensile Yield Strength:

The test results reveal that the tensile yield strength is highest at 4% of MoS2 reinforcement of

the particles. From the microstructure it is observed that the distribution of reinforcement is

good at 4 % of MoS2. For the remaining wt % the distribution shows some voids. Due to this,

there is decrement in the Tensile Yield Strength (figure 6).

4.4 Impact strength:

The test results reveal that the impact strength is highest at 4% of MoS2 reinforcement of the

particles. From the microstructure it is observed that the distribution of reinforcement is good

at 4 % of MoS2. For the 1%, 2%, 3%, 5% and 5.5% the distribution of reinforcement particles

are not uniform. Due to this, the variations in the Impact strength is observed in figure 7.

4.5 Hardness:

The tests revealed that, the hardness of the composite specimen had increased gradually with

increase in the wt % of MoS2 powder incorporated in the MMC up to 4 %, and then decreased

on further increment of reinforcement i. e 5 % and 5.5%.. The trend of increase in hardness is

shown in fig 8. This is due to the reinforcement of MoS2 particles are not uniformly

distributed.

4. CONCLUSIONS

The present work deals with the preparation and characterization of Al- MoS2 Metal Matrix

composite. The following conclusions are made from the study.

1. Al 6061 / MoS2 MMCs were successfully fabricated.

2. The hardness of the MMC is found to be maximum for 4% MoS2.

3. The tensile strength of the MMC is found to be maximum for 4% MoS2.

4. MMC with 4% MoS2 is found to be the best material based on the characterization of

the mechanical properties.

ACKNOWLEDGEMENT

The authors expressing profuse gratitude to Linsons Alloys Pvt. Ltd. Hyderabad and

Raghavendra Spectro analysis , Hyderabad for extending their facilities to cast the MMC

specimens as well for testing.



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STUDIES ON CHARACTERIZATION OF AL 6061/ MOS 2 · PDF fileCh.V.S.ParameswaraRao Professor,...

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