Experimental Fig4.1. The molten metal was agitated by use

Experimental
Details

Material
Selection

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Matrix material

            Aluminum 6063 was used as matrix
material owing to its excellent mechanical properties coupled with good
formability and its wide applications industrial sector.The Physical
composition of the material is given in table 1

Sl.No

Property

Value

1

Density

2700 kg/m3

2

Melting Point

600°C

3

Modulus of
Elasticity

69.5 GPa

4

 Electrical Resistivity 

0.035×10-6 ?.m

5

Thermal
Conductivity

200 W/m.K

6

Thermal
Expansion

23.5 x 10-6 /K

Table 1 shows
Physical  composition of Al6063

 

The Chemical composition of the material is given in
table 2

Elements

Si

Fe

Cu

Mn

Mg

Al

%
(max.)

0.2%-0.6%

0.35%
3

0.10%
4

0.8

0.10%

Balance

Table 2 shows chemical composition of Al6063

 

Reinforcement

Silicon
Carbide was chosen as reinforcement owing its high hardness and low
co-efficient of thermal expansion. SiC is highly wear resistant and also has
good mechanical properties, including high temperature strength and thermal
shock resistance. The particle size of the reinforcement used are in range
of  10µm to 20µm.

Preparation of
Composites

            A
batch of 3.5kgs of Aluminum 6063alloy 
was melted using a 6KW electric furnace as shown in Fig4.1. The molten
metal was agitated by use of mechanical stirrer rotating at a speed of 300 rpm
to create a fine vortex.   Preheated SiC
powders (preheated to 700oC for 2 hrs) were added slowly in to the vortex
while continuing the stirring process.  
The stirring duration was 10 min.  
The composites melt maintained at a temperature of 710oc was
then poured in to metallic molds as shown in Fig 2.  The stirrer blades made of stainless steel
and were coated with ceramic material to minimize the iron pickup by the molten
metal.   The amounts of SiC was varied
from 0 to 8wt% in steps of 2 wt%.

Preparation of Samples

The samples were prepared for
hardness test, tensile test, Compressive tests. 
The samples were prepared for the above tests to find mechanical
properties. The photographs of the samples prepared for the above tests are
given below

Fig 3
Preheating of mould

Fig: 4Pouring
of molten material into mould

 

Fig 5 Specimen
prepared for Tensile testing

Fig 6 Specimen
for Compression test

Fig 7 Specimen
for Hardness test

Fig 8 Specimen
attached in UTM for tensile test

 

Fig 9:Output
result of tensile test

 

 

 

Result
and Discussion

Sl.No

%SiC by Weight

Hardness in BHN

Average Hardness in BHN

 

 

Section 1

Section 2

Section 3

 

1

0

28.5

28.5

28.5

28.5

2

2

31

31

32

31.33

3

4

39.5

39

39

39.16

4

6

45

45.5

46

45.5

5

8

58

57.5

58

57.83

The variation of hardness with increase content of
SiC particles in the matrix Al6063 in as cast condition and with reinforcement
varying from 0-8% SiC  is  shown 
in Fig. 10.  It  is 
observed  that  with  
increase in percentage of Silicon carbide the hardness is increaseed

Fig
10: Brinell hardness number for different Wt % of SiC

 

 

Fig
11: Compression strength for different Wt % of SiC

 

The test results reveal that as wt % of SiC is
increased the compressive strength is also decreased there  is a very drastic decrease in compressive
strength for 2% may be due to improper casting or casting defects

Figure 11 shows the test results for
different Weight percentage of Silicon carbide added in Aluminum 6063 there is
a fair result obtained as silicon carbide is ceramic material and it is brittle
in nature the strength has decreased with increase percentage addition to
aluminum 6063 alloy

 

 

 

Fig 12
Load at Yield

Figure
5.3
 shows that the load at which the
yielding started for different weight percentage of Silicon carbide and from
the test results reveals a very fair results, as it is observed from the graph
for 0% of SiC the load at the yield is 5.46, and at 2% the load is increased to
7.3 there is increased in the load carrying capacity of material with increase
in silicon carbide as aluminum is ductile in nature and silicon carbide is
brittle in nature so reinforcing the silicon carbide the load taking ability of
material is increased the table below shows the variation of loads  at yields

L:oad at Yield

0

5.46

2

7.3

4

9.28

6

9.46

8

8.56

 

5.2.2Elongation
at Yield

Fig 13
Elongation at yield

  Figure
5.4  shows that beginning of Elongation as  yielding of specimen starts for different
weight percentage of SiC, as it is observed from the graph for 0% of SiC the
elongation at yield is 13.6 and at 2% elongation is increased to 16.37, at 4%
26.08mm,  there after  there is sudden decrease in elongation with
increase in SiC, the elongation is property of ductile material as SiC is
increased the elongation is decreased as SiC is ceramic material which is very
brittle in nature. table below shows the variation of elongation.

Elongation at Yield

0

13.6

2

16.37

4

26.08

6

20.35

8

13.94

 

 

 

 

 

 

 

5.2.3
Yield Strength

Fig 14 Yield Strength

Figure
5.5
shows that the yield strength at which the yielding started for different
weights percentage of SiC and from the test results. Yielding of material is
nothing but the point where the material just start changing its shape and
size. As it is observed from graph for 0% of SiC i:e Pure Aluminum 6063 alloy
the yield strength is 45.286 and for 2% the yield strength is increased to
60.158. The yield strength of material is increased upto 6% of reinforcement of
SiC there after there is sudden drop in yield strength with is increase in SiC.
Due to improper weight fraction of SiC and aluminum alloy 6063, The table below
shows the values of Percentage variation to yield strength values.

Yield Stress

0

45.286

2

60.158

4

76.229

6

112

8

70.541

 

 

Fig 15 Tensile strength

Figure
5.7
shows the variation of tensile strength for different weight percentage of SiC.
Tensile strength is the major properties in mechanical properties  the material’s tensile property defines about
material strength in tension. The test is conducted for tensile strength for
different weight percentage of SiC  as
reinforcement in Aluminum 6063 alloy in step of 2% from 0%to 8%, in order to
increase the tensile strength of material. The test result reveal a very fair
result, as it is observed from the graph for 0% of Sic the tensile strength is
82.775, at 2% of SiC the tensile strength increases to 75.815 , at 4% of SiC
the tensile again increases to 86.415 at 6% and further there is increase in
the tensile strength to 90.319 at 8%. So its is concluded from the graph with
increase in reinforcement of SiC there is increase in Tensile strength. The
table below shows the values of Weight Percentage variation of SiC to Tensile
strength values.

Tensile
Strength

0

82.775

2

75.815

4

86.415

6

92.288

8

90.319

Percentage Reduction in Area

Fig 16 %
reduction in area

Figure
 shows the percentage reduction in area with
different weight percentage of SiC and from test results reveals a very fair
results, as it is observed from the graph for 0% of SiC the percentage
reduction in area is 5.41 and at 4% of SiC the percentage reduction in area is
4.98 further there is decrease in the percentage reduction in area. The area of
reduction at the point where it breaks. With increase in SiC Deformation of
material reduces as the property of material starts changing from ductile to
brittle. The area calculated is know as Cup and Cone fracture measured where
the fracture takes place.  The table
below shows the values of Weight Percentage variation of SiC to Percentage
reduction in area

 

 

% Reduction Area

0

5.41

2

4.98

4

4.76

6

4

8

3.55

 

 

CONCLUSIONS

 

Silicon carbide particle reinforced
aluminium matrix composite 6063 (AMCs) were prepared by stir-casting with different
particle weight fraction (0%,2%, 4%, 6%, and 8%) the following conclusions can
be drawn:

Ø  The
composites containing 6063Al with 0,2,4,6 and 8wt% of Silicon particulates were
successfully synthesized by melt stirring method using three stages mixing
combined with preheating of the reinforcing particles.

Ø  Hardness
of Al-SiC is much better than the aluminum metal. In case of increased silicon
carbide content, the hardness, and material toughness are enhanced and highest
value is obtained at 8% SiC content.

Ø  Homogenous
dispersion of SiC particles in the Al matrix shows an increasing trend in the samples
prepared by without applying stirring process, with manual stirring

Ø  It
has been inferred that the tensile strength of sample 4 is marginally higher
than other  samples because of its
aluminum content.

Ø  It
has been noted that the Compressive strength of sample 1 is higher than other
samples.

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