1. A Project Work on
MECHANICAL BEHAVIOUR OF Al ALLOY
REINFORCED WITH Al2O3/RICE HUSK ASH PARTICLES
SYNTHESIZED BY STIR CASTIING
University VOC College of
Engineering
Tuticorin Campus

2. PROJECT MEMBERS
S. Marimuthu @ Mathavan [953211114021]
P. Pon Rajesh Kumar [953211114032]
R. Sivagaminathan [953211114049]
M. Vignesh [953211114055]

3. PROJECT GUIDE : Mr. S. AMAL BOSCO JUDE(Ph.D), AP/MECH
PROJECT CO-GUIDE : Mr. P. VENKALAKUMAR, TF/MECH

4. ABSTRACT
 In the past few years the global need for low cost, high
performance and good quality materials has caused a shift in
research from monolithic to composite materials.
 Present work is focused on the study of behavior of
Aluminum Alloy (AA6061) with Alumina and rice husk ash
particulate composite fabricated by double layer feeding stir
casting technique.
 Different wt% of alumina powder and rice husk ash is used as
reinforcement phase in this AMMC.
 The mechanical behaviour of these composites with different
wt% of alumina and rice husk ash are investigated by Tensile
Test, Hardness Test, Flexural Test, Density Measurement and
Microstructural Behaviour.

5. PROBLEM DEFINITION
 In India, we are mostly using coal based fuel cars which is non-
conventional source of energy.
 So fuel economy became dominant while designing cars in India.
 One approach to increase an automobile’s fuel economy by
reducing vehicle weight and friction loss simultaneously is to remove
the cast iron cylinder block and replace them with a lighter more
thermally efficient material.

6. INTRODUCTION TO HYBRID MMC
 Composites – mixture of two/more constituents
insoluble in each other.
 Properties better than sum of their constituents.
 Hybrid Composites - Incorporation of several different
types of particulates into single matrix.
 Advantages of Aluminum Matrix Composite (AMC)
• Low density
• High Strength
• Superior creep resistance
• High damping resistance
• Good dimensional stability

7. METHODOLOGY
MATERIALS
Aluminum Alloy
Alumina
Powder
Rice Husk Ash
(After
Pretreatment)
FABRICATION
(Stir Casting)
AMC with 2 wt% of
Alumina & RHA
AMC with 4 wt% of
Alumina & RHA
TESTING
(Density Measurement,
Tensile Test, Hardness Test,
Flexural Test)

8. ALUMINIUM ALLOY
The aluminum alloy used in our project work is AA 6061, which has
major composition of magnesium and silica.
The Chemical Composition of AA 6061 is given below
Element Mg Fe Si Cu Mn V Ti Al
Weight % 1.08 0.17 0.63 0.32 0.52 0.01 0.02 Remainder

9. Alumina Powder
The reinforcement of Alumina (Al2O3) with the average
size of 25µm into aluminum matrix improves
 Hard, Wear Resistant
 Resist alkali attacks at high temperature
 Good thermal conductivity
 High Strength and Stiffness

10. Rice Husk Ash (RHA)
 The second particulate reinforcement is RHA obtained from Rice
Husk
 Rice Husk is used in small boilers for heat generation
 The RHA obtained is rich in silica and carbon content, when
disposed in environment causes pollution.
 In order to used RHA as a reinforcement in
Aluminum matrix Composite, it has to be
pretreated to remove carbonaceous material.

11. Pretreatment of RHA
 The Rice Husk is thoroughly washed with water to remove dust
and dried at room temperature for 1 day.
 Heated to 200˚C for 1h to remove moisture and volatile
materials.
 Heated to 600˚C for 5h to remove carbonaceous material.
 It was observed that colour of ash changes from black to grayish
white.
 The change in colour is due to removal of carbonaceous material.
 The end product is Silica rich RHA.

12. Before heat treatment After heat treatment

13. XRD pattern of heat treated RHA
Chemical composition of heat treated RHA

14. FABRICATION OF ALUMINUM MATRIX COMPOSITES
 Stir casting (Melt stirring) process, which is one of the liquid
metallurgy technique is used to AMC.
 The advantages of using this techniques are
 wide selection of materials
 better matrix-particle bonding
 easier control of matrix structure
 simple and less expensive
 flexibility
 However some problems with stir casting includes
 poor wettability
 porosity
 heterogeneous distribution

15. Improve Wettability
• Molten matrix cannot wet the surface of reinforcement material
• Hence alumina and RHA particles donot mix with aluminum
matrix, instead float on melt surface due to
1. Surface tension
2. Large specific surface area
3. Oxide films on melt surface
• To eradicate this problem 1 wt% MAGNESIUM is added to the
composites.
• The addition of magnesium improves wettability of
reinforcements.
• The reinforcements are also preheated before processing to
remove adsorbed gases in the particle surface.

16. MAGNESIUM POWDER

17. Reduce Porosity
 Porosity is due to presence of insoluble gases such as hydrogen
present in the molten aluminum alloy.
 The insoluble gases can be remove with the help of degassing tablet.
 The degassing tablet is Hexa Methyl Formate which is an organic
compound that removes insoluble gases from the molten aluminum
alloy.
Degassing Tablet

18. Homogeneous Distribution
 The next problem is distribution of reinforcement in the molten matrix
 After Wetting particles tends to float or sink according to density
difference between matrix reinforcements and matrix alloy melt
 Thus leading to high tendency for clustering
 To accompany uniform distribution, the following factors has to be
considered
 The number of blades in the stirrer should be 4
 The blade angle must be 45˚ or 60˚
 Blade should 20mm above the bottom of the crucible
 The feed rate of reinforcements must be uniform
 The flow pattern of reinforcements should from outward to
inward
 The metal pouring rate should be constant to avoid bubble
formation.

19. Hand Stirrer Mechanical Stirrer Setup
Blades of Mechanical Stirrer

20. STIR CASTING EQUIPMENT

21. STIR CASTING PROCEDURE
Aluminum alloy is
weighed and cut into
pieces and placed in
graphite crucible
Preheating of weighed
Alumina & RHA to
200˚C for 1h
Al alloy melted in
furnace at 800˚C
Addition of degassing
tablet
Addition of 1 wt% Mg
powder
Addition of preheated
Alumina to crucible
Addition of
preheated RHA to
crucible
Mechanical Stirring at
950rpm
Final casting poured to
preheated mould

22. Sample
Matrix [ A6061
Alloy ]
Reinforcements
Alumina Rice Husk
Ash
1. 100 0 0
2. 96 2 2
3. 92 4 4
Composition of Samples

23. AA 6061 pieces in Graphite Crucible of furnace Weighing of Alumina
Weighing of
RHA

24. Hand Stirring
Mechanical Stirring
Pouring of Casting to mould Finished Product

25. RESULTS AND DISCUSSION
The Aluminum Matrix composites with 2 and 4 wt% of Alumina
& RHA is subjected to following measurements to evaluate its
mechanical properties
 Tensile Test
 Hardness Test (Brinell’s Hardness)
 Flexural Test
 Density Measurement
 Micro-structural Behaviour using SEM

26. Tensile Test
 The specimen for tensile test were prepared according to ASTM E8
standard
 This is used to determine elastic limit, elongation, proportional limit,
and reduction in area, ultimate tensile strength, yield point and yield
strength
 The Ultimate Tensile Strength (UTS) and percentage elongation of the
specimen are tabulated

27. 80 84
96
60
80
100
Pure 2% 4%
UTSMPa
Wt% of RHA and Al2O3
Ultimate Tensile Strength (UTS) of fabricated samples
14
6.84 4.8
0
10
20
Pure 2% 4%
%elongation
Wt% of RHA and Al2O3
% elongation of fabricated samples

28. Hardness Test
Hardness of the hybrid composites were measured using a
standard Brinell’s Hardness tester as per ASTM E10 standards.
Where F is the applied load, D is the diameter of the steel
ball and d is the size of the indent.

29. 33
57 61
0
50
100
Pure 2% 4%
HardnessBHN
Wt% of RHA and Al2O3
Hardness of Fabricated Samples

30. Flexural Test
 The transverse bending specimen is employed in which a rod specimen
having a rectangular cross section is bent until fracture using three-point
loading technique.
 The stress at failure is known as flexural strength.
 The Flexural strength is calculated for the unreinforced and A6061/
Al2O3 /RHA composites using 3 point loading technique.

31. Test piece after flexural test
164
281
407
0
500
Pure 2% 4%
Flexural
StrengthMPa
Wt% of RHA and Al2O3
Flexural Test of Fabricated Samples

32. Density Measurement
 Density measurement is carried out on base material and reinforced
sample using Archimedes principle.
 The formulae used to calculate density is given below
ρmmc = mρw/(m-m1)
where
m is the mass of the composite sample in air
m1 is the mass of the same composite sample in distilled water
ρw is the density of the distilled water.
The density of distilled water at 20 ◦C is 998 kg/m3.

33. 2755
2710
2690
2650
2700
2750
2800
Pure 2% 4%
Density(Kg/m3)
Wt% of RHA and Al2O3
Density of Fabricated
Samples

34. Microstructural Behaviour
 The SEM is a microscope that uses electrons instead of light
to form an image.
 Good retention of rice husk ash particles was clearly seen in
the microstructures of A6061/ Al2O3 /RHA composites.
I. SEM picture of A6061/2% Al2O3 &RHA Composites
II.SEM picture of A6061/4% Al2O3 &RHA Composites

35. Mechanical Properties of Matrix and hybrid
composites
S.
no.
Sample
Hardness
BHN
UTS
MPa
%
elongatio
n
Flexura
l Test
MPa
Density
Kg/m3
1. AA 6061 33 80 14 164 2755
2.
AA 6061 with
2wt% of RHA and
Al2O3
57 84 6.84 281 2710
3.
AA 6061 with
2wt% of RHA and
Al2O3
61 96 4.8 407 2690

36. Discussions
 The results confirmed that stir formed AA 6061 with RHA / Al2O3
reinforced composites is clearly superior to base AA 6061 in the comparison of
tensile strength, Flexural strength as well as Hardness.
 Dispersion of RHA / Al2O3 particles in aluminum matrix is investigated
using SEM image.
 It appears from this study that UTS starts increases with increase in weight
percentage of RHA and Al2O3 in the matrix.
 The Hardness increases after addition of RHA / Al2O3 particles in the
matrix.
 Stir casting process, stirrer design and position, stirring speed and time,
particle- preheating temperature, particle incorporation rate etc. are the
important process parameters.

37. Conclusions
The results confirmed that the stir formed Al alloy with
Al2O3&RHA reinforced composites is clearly superior to base Al alloy in the
comparison of Ultimate Tensile Strength, Hardness and Flexural Strength.
Dispersion of Al2O3&RHA particles in the aluminum matrix
improves hardness and reduce density of the matrix material.
Aluminum matrix composites have been successfully fabricated by
stir casting technique with fairly uniform distribution of Al2O3&RHA
particles.

38. ACKNOWLEDGEMENTS
We convey our sincere thanks to
 Dr.S.SANKARAN, Ph.D., Associate Professor, Department of Metallurgical &
Materials Engineering, IIT Madras
 Mr.N.THIRUNAVUKARASU, Sr. Technician, Department of Metallurgical &
Materials Engineering, IIT Madras
 Mr.N.SANKARESWARAN,M.E.,(Ph.D), AP/Mech, Anna University – Tirunelveli
Region
We are indeed very thankful to our
 Dean, Dr.N.SHENBAGA VINAYAGA MOORTHI, M.E, Ph.D.
 HOD, Dr.R.A.MALAIRAJAN,M.E.,Ph.D.,M.B.A., AP/Mech
 Guide, Mr. S. AMAL BOSCO JUDE, M.E.,(Ph.D), AP/Mech
 Co-Guide, Mr.P.VENGALAKUMAR, M.E., TF/Mech
 Project Co-ordinator, Mr.A.KARTHIKEYAN, M.E.,(Ph.D), AP/Mech

39. References
1. Autar K.Kaw (2013) ‘Mechanics of Composite Materials’, CRC press.
2. Balasubramanian R (2010) ‘callister’s Material Science and Engineering’,
Wiley-India (P) Ltd.
3. Rajeshkumar Gangaram Bhandare et al, 2013. Preparation of
Aluminum Matrix Composite by using Stir Casting Method,
IJEAT, ISSN:2249-8958, Volume-3, Issue-2.
4. Atunaya, C.U., Aigbodicon, V.S., 2014. Evaluation of Al-Cu-Mg
alloy / bean pod ash nanoparticles synthesis by double layer
feeding-stir casting method. Elsevier Ltd.
5. Himanush Kala, Mer, K.K.S., Sandeep Kumar, 2014. A Review on
Mechanical and Tribological Behaviors of Stir Cast Aluminum
Matrix Composites. 2211-8128, Elsevier Ltd.

40. THANK YOU