By P.vinoD Final Year M.tech(Nano Technology) Department of Metallurgical Engineering

8/14/2019 By P.vinoD Final Year M.tech(Nano Technology) Department of Metallurgical Engineering

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By

P.VINODFinal Year M.Tech(Nano Technology)Department OF Metallurgical Engineering

Andhra university college of engineering (A)Visakhapatnam


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CONTENTS

1 INTRODUCTION

2 OBJECTIVES

3 EXPERIMENTAL DETAILS

4 RESULTS AND DISCUSSIONS

5 CONCLUSIONS


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INTRODUCTION


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1. Nanotechnology literally means any technology performed on a nano

scale that has applications in the real world.

2. The Present Work Considered metal matrix composites reinforced

withNANO sized discrete particles.

3. The term composite broadly refers to a material system which is

composed of a discrete constituent (the reinforcement) distributed in

a continuous phase (the matrix).

4. Conventional stir casting technology has been employed for

producing particulate reinforced metal matrix composites.


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The major problem in this technology is to obtain sufficientwetting of dispersion by the liquid metal and to get a

homogeneous dispersion of the ceramic particles.

In AMCs one of the constituent is aluminum/aluminum alloy,which forms percolating network and is termed as matrix

phase.

The other constituent is embedded in this aluminum/aluminum

alloy matrix and serves as reinforcement,.


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Advantages of AMCs over unreinforced materials

Greater strength Improved stiffness Reduced density (weight)

Improved high temperature properties Controlled thermal expansion coefficient Thermal/heat management Enhanced and tailored electrical performance

Improved abrasion and wear resistance Control of mass (especially in reciprocating applications) Improved damping capabilities.


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OBJECTIVE

The objective of this work is to produce a nanocomposite andobserve the hardness values.

The effects of Sic particle content on the hardness of the

composites were investigated.

Based on experiments, hardness was improved by incorporation

of nano-Sic into matrix.

The improvement in values of hardness was observed in this

experiment is due to small particle size and good distribution of

the Sic particles.


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EXPERIMENTAL WORK


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Materials

1. 1 kg Aluminum ignot(99% purity)2. 60 grams of silicon carbide(197nm)

Practical Equpiment

1. High energy planetary ball milling2. X-ray diftractometer3. Clay-graphite crucible in a resistance furnace.4. Graphite stirrer

5. Muffle furnace


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High energy ball milling

The reduction in particle size of silicon carbide from micron level to the nanolevel was carried out using a high-energy planetary ball mill.

The ball mill was loaded with BPR (Ball to powder weight ratio) of 10:1. The rotation speed of the planet carrier was 200 rev min-1.

First 60 grams of silicon carbide powder was taken and ball mill it for 15 hourswith the 3 mm balls. Another 20 hours milled with 2mm balls.

The sample was taken out after every 5 hours of milling.

After the completion of each 5 hours checked it for crystallize size using XRD


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Vial- Balls- Lid-Gasket Set

High Energy Planetary Ball Mill(Model: Retsch, PM 100, Germany)


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X - RAY DIFFRACTION STUDIES

In order to characterize the silicon carbide powder by using X-RayDiffract meter.

we have to take the silica glass plate and disperse the powder

uniformly on the space providing on it.

Take 10mm divergence slit in order pass the X-rays through the

sample.

The samples were scanned in the range from 15 to 90 degrees 2-

and analyzed for crystallite size, peak height and crystallinity by

using X-Ray Diffractometer


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X-Ray Diffractometer (Model: 2036e201; Rigaku,

Ultima Iv, Japan)


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Closer View of the Set Up


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STIR CASTING OF COMPOSITE

o Thepure aluminum alloy was used as a matrix material.

o Fly-ash powder was added as reinforcement particles.

o All the melting was carried out in a clay-graphite crucible in a resistance furnace.o The furnace temperature was first raised above the liquidus to melt the aluminum

alloy completely.

o At this stage Fly-ash particles were added and mixed manually.

o when the aluminum alloy was in a semi-solid state and then automaticmechanical mixing was carried out for 10 minutes by using an graphite stirrer anaverage stirring rate of 550-650 rpm.


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o In the final mixing processes, the furnace temperature was

controlled to be within 73010 C.

o Mechanical stirring could indeed mix the particles into the melt.

o After the composite preparation the samples are homogenized at the

temperature of 1800c for 30 hours in a muffle furnace.

o For each two hours we have collected the samples and observe the

Rockwell B scale (1/8 inch red indenter) hardness of each sample.


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Schematic Representation of Dispersion Process


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RESULTS AND DISCUSSIONS


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X - RAY DIFFRACTION STUDIES

The X-ray diffraction measurements for ball milled samples were

carried out with the help of a Goniometer model 2036E201 using

Cu Kradiation (K

= 1.54056 A0) at an accelerating voltage of 40

KV and a current of 20 mA.

The samples were scanned in the range from 15 to 75 degrees 2-

and analyzed for crystallite size, peak height and crystallinity by

using X-Ray Diffractometer


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xrd results showing intensity versus 2 theta angle for different samples

which are taken at regular intervals


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sults showing intensity versus 2 theta angle for samples of initial and final sam


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CRYSTALLITE SIZE DETERMENATION

The average crystallite size was determined from the full width at

half maximum (FWHM) of the X ray diffraction peak using

Scherers equation.

Crystallite size = (k) / (FW(S)*cos)

wavelength =1.548 A0

FW(S) ^D=FWHM^D-FW (I) ^D


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No of Hours 2theta FWHM CrystaliteSize(nm)

0 26.617 0.120 197.93

5 26.617 0.128 151.29

10 26.618 0.133 133.29

15 26.617 0.136 124.23

20 26.618 0.138 119

25 26.617 0.151 94.95

30 26.617 0.163 80.61

35 26.602 0.189 61.53


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variation in crystallite size withmilling time.


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HARDNESS TESTING

stir casting samples


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Aluminum metal may be hardened by the uniform dispersion of the2% volume of the in silicon carbide particles of very hard and inert

materials.

Strengthening mechanism involves interaction between the particles

and dislocations within the matrix, as with precipitation hardening.

After completion of the stir casting procedure the samples are

homogenized.

The samples are collected at regular intervals and check hardness

values using Rockwell B scale.


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No Of Hours RockwellHardness

2 22.5

4 386 55.5

8 68.5

10 72

12 74

14 76

16 79

18 82

20 84

22 86

24 86

26 86

28 86

Rockwell hardness values withreference to time.


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Hardness vs.Time.


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CONCLUSIONS


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1. The crystallite size of the silicon carbide powder was reducedfrom 197 nano meters to the 58 nano meters.

2. The Rockwell B scale hardness values are increasing with thehomogenizing time.

3. The values of hardness are initially 22.5 and after homogenizing itfor 28 hours in the muffle furnace.The final value is reached up to

86.

4. the hardness values improved .


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By P.vinoD Final Year M.tech(Nano Technology) Department of Metallurgical Engineering