UNIVERSITI TEKNIKAL MALAYSIA MELAKA

FABRICATION OF STRONTIUM FERRITE

MAGNETIC MATERIAL THROUGH WET

PROCESSING

Thesis submitted in accordance with the partial requirements of the

Universiti Teknikal Malaysia Melaka for the Bachelor

Of Manufacturing Engineering (Engineering Materials) with Honours

By

Nik Norzaliza binti Long Hassan

Faculty of Manufacturing Engineering

May 2008

UTeM Library (Pind.1/2007)

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

BORANG PENGESAHAN STATUS LAPORAN*

JUDUL: Fabrication of Strontium Ferrite Magnetic Material through Wet

Processing.

SESI PENGAJIAN: 2007/2008

Saya Nik Norzaliza Binti Long Hassan

mengaku membenarkan tesis (PSM/Sarjana/Doktor Falsafah) ini disimpan di Perpustakaan Universiti Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat kegunaan seperti berikut:

1. Tesis adalah hak milik Universiti Teknikal Malaysia Melaka dan penulis.2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan untuk tujuan pengajian sahaja dengan izin penulis.3. Perpustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran antara institusi pengajian tinggi.4. **Sila tandakan (√)

SULIT

TERHAD

TIDAK TERHAD

(Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia yang termaktub di dalam AKTA

RAHSIA RASMI 1972)

(Mengandungi maklumat TERHAD yang telah ditentukan oleh organisasi/badan di mana penyelidikan dijalankan)

(TANDATANGAN PENULIS)

Alamat Tetap: Lot 506, Kampong Kemasin, Perupok,

16300 Bachok, kelantan

Tarikh: _______________________

Disahkan oleh:

(TANDATANGAN PENYELIA)

Cop Rasmi:

Tarikh: _______________________

** Jika tesis ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan dengan menyatakan sekali sebab dan tempoh tesis ini perlu dikelaskan sebagai SULIT atau TERHAD.

FAKULTI KEJURUTERAAN PEMBUATAN

Rujukan Kami (Our Ref) : 20 Mei 2008Rujukan Tuan (Your Ref):

Pustakawan Perpustakawan Universiti Teknikal Malaysia MelakaUTeM, No 1, Jalan TU 43, Taman Tasik Utama, Hang Tuah Jaya, Ayer Keroh, 75450, Melaka

Saudara,

PENGKELASAN TESIS SEBAGAI SULIT/TERHAD- TESIS SARJANA MUDA KEJURUTERAAN PEMBUATAN (Department of Materials Engineering): Nik Norzaliza Binti Long Hassan.TAJUK: Fabrication of Strontium Ferrite Magnetic Material through Wet Processing.

Sukacita dimaklumkan bahawa tesis yang tersebut di atas bertajuk “Fabrication of Strontium Ferrite Magnetic Material through Wet Processing” mohon dikelaskan sebagai terhad untuk tempoh lima (5) tahun dari tarikh surat ini memandangkan ia mempunyai nilai dan potensi untuk dikomersialkan di masa hadapan.

Sekian dimaklumkan. Terima kasih.

“BERKHIDMAT UNTUK NEGARA KERANA ALLAH”

Yang benar,

.........................DR AZIZAH SHAABANPensyarah, Fakulti Kejuruteraan Pembuatan (Penyelia Bersama)No telefon: 06-2332122Email : azizahs@utem.edu.my

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

Karung Berkunci 1200, Ayer Keroh, 75450 Melaka

Tel: 06-233 2421, Faks : 06 233 2414 Email: fkp@kutkm.edu.my

DECLARATION

I hereby declare that this report entitled FABRICATION OF STRONTIUM FERRITE

MAGNETIC MATERIAL THROUGH WET PROCESSING is the result of my own

research except as cited in the references.

Signature : ……………………………………Author’s Name : Nik Norzaliza Binti Long HassanDate : 20.05.2008

ii

APPROVAL

This report is submitted to the Faculty of Manufacturing Engineering of UTeM as a

partial fulfillment of the requirements for the degree of Bachelor of Manufacturing

Engineering (material engineering). The members of the supervisory committee are as

follow:

…………………………..

Dr Azizah Shaaban (Main Supervisor)

iii

ABSTRACT

The purpose of doing this project is to evaluate the phase composition for

calcined ferrite using SEM-EDX and XRD and to evaluate microstructure effects on

calcined materials. The raw material used in this study is strontium ferrite which is

combination between strontium carbonate and iron oxide. The material was mill and

mixed with ethanol during ball milling process. The next process continues with

calcined in 12500C of temperature and followed by crushing process. First sample is

sintered at 12500C and second sample sintered at 12700C. Then the calcined powder is

mixed by using 2 different percentages of Nickel using Tambling mixing. Third sample

consist of 1% of Nickel and 99% of calcined powder and fourth sample is consisting 2%

of Nickel and 98% of calcined powder. Both of third and fourth samples are sintered at

12700C. The grains size of ferrite is analysis with Scanning Electron Microscope (SEM)/

EDX and XRD. Backscattered image is carried out from the EDX to evaluate the

chemical analysis and morphology. Physical analysis of the sample is carried out using

Electronic densimeter to measure the density. The main phase compositions in calcined

powder are strontium ferrite and Fe2O3. SEM indicated that a continuous network of

pores exist in the microstructure make the value of density low. Besides, it could be

observed that there were small amount of Nickel on the surface of grains boundaries.

Addition of Nickel as additive strongly affects the structural and morphological of the

samples.

iv

ABSTRAK

Projek ini adalah bertujuan untuk menilai komposisi fasa pengkalsinan ferrite

dengan menggunakan SEM-EDX dan XRD dan untuk menilai kesan pengkalsinan ke

atas struktur mikro bahan. Bahan mentah yang di gunakan dalam kajian ini ialah

strontium ferrite di mana terhasil daripada kombinasi antara strontium carbonate dan

iron oxide. Bahan ini mesti di kisar dan dicampur dengan ethanol semasa proses

pengisar bebola. Proses di ikuti dengan pengkalsian pada suhu 12500C dan seterusnya

dengan proses penggempuran. Sampel pertama disinter pada 12500C dan sampel kedua

disinter pada suhu 12700C. Kemudian bahan pengkalsinan di campur dengan dua jenis

peratusan Nikel yang berbeza secara ‘tambling’. Sampel ketiga terdiri daripada 1%

Níkel dan 99% serbuk pengkalsinan. Sampel keempat pula terdiri daripada 2% Nickel

dan 98% serbuk pengkalsinan. Sampel ketiga dan keemapat kemudiaanya di sinter pada

suhu 12700C. Saiz butiran ferit di analisis dengan mengunakan Scanning Electron

Microscope (SEM)/ EDX dan XRD. Imej backscattered dilakukan dengan EDX untuk

manjalankan analisis kimia dan morfologi. Analisis fizik sampel dijalankan

menggunakan Elektronik densimeter untuk mengukur ketumpatan. Fasa utama yang

terdapat dalam serbuk pengkalsinan adalah stontium feritte dan Fe2O3. SEM

menunjukkan rangkaian liang-liang yang wujud dalam mikrostruktur menyebabkan nilai

ketumpatan menjadi rendah. Selain itu, boleh diperhatikan terdapat unsur Nikel di

permukaan sempadan butir tapi hanya dalam jumlah yang kecil. Secara jelasnya

penambahan Nikel sebagai bahan tambahan dalam serbuk pengkalsinan menjejaskan

struktur dan mofologikal sampel.

v

ACKNOWLEDGEMENT

I would like to express my appreciation to the individuals who had played a part

in ensuring a successful occurrence and flow of activities throughout the duration of my

final year project. Endless appreciation and gratitude to my supervisor, Dr Azizah

Shaaban and to my first panel Dr Warikh for their encouragement and support and for

spending quite some time with myself, providing a lot of guidance and ideas for my

project research. Their knowledge and experience really inspired and spurred myself. I

truly relished the opportunity given in working with them. Last but not least, my

appreciation to Mr. Mohd Azhar Shah b. Abu Hassan , Mr. Hairulhisham b. Rosnanm Mr

Mahader bin Muhamad, Mr Sarman and all technicians involved to complete this project.

Finally, my sincere appreciation is dedicated to my parents and family and as well as the

friends for their priceless assistance and patronage throughout the process of data

gathering.

vi

TABLE OF CONTENT

DECLARATION iiAPPROVAL iiiABSTRACT ivABSTRAK vACKNOWLEDGEMENT viTABLE OF CONTENTS viiLIST OF FIGURES xiLIST OF TABLES xvLIST OF ABBREVIATIONS, SYMBOLS,

SPECIALIZED NOMENCLATURES

xvi

CHAPTER 1 INTRODUCTION1.1 Background of the project 11.2 Problem Statement 11.3 Objectives 21.3 Introduction on Magnetic material 2

1.4.1 Ceramic material 21.4.2 Ceramic magnet 31.4.3 Properties of magnetic material 41.4.4 Application of magnetic material 6

CHAPTER 2 LITERATURE REVIEW2.1 Type of magnetism 7

2.1.1 Diamagnetism 72.1.2 Paramagnetism 82.1.3 Antiferromagnetism 82.1.4 Ferrimagnetism 82.1.5 Ferromagnetism 92.2 Type of ferrites 102.2.1 Hard ferrite 112.2.2 Soft ferrite 122.2.3 Other type of magnetic materials 12

2.3 Starting material for strontium ferrite 15 2.3.1 Strontium carbonate 15

vii

2.3.2 Iron oxide 15 2.3.3 Ethanol 16 2.3.4 Nickel 162.4 Previous research on strontium ferrite 17

2.4.1 Process parameter selection for strontium

ferrite sintered magnets using Taguchi L9

orthogonal design.

17

2.4.2Barium and Strontium ferrite perpendicular

thin film media with a sendust soft

magnetic underlayer.

18

2.4.3Fine powders of SrFe12O19 with SrTiO3

additive prepared via a quasi-dry

combustion synthesis route

19

2.4.4 Microstructure of pre-sintered

permanent magnetic strontium ferrite

powder

19

CHAPTER 3 METHODOLOGY3.1 Powder processing 21

3.1.1 Milling and mixing 223.1.2 Calcinations 243.1.3 Crushing 253.1.4 Sieving 253.1.5 Mixing 263.1.6 Compact 263.1.7 Sintering 28

3.2 Sample Characterization 28 3.2.1 Sample preparation for microstructure

evaluation

28

3.2.2 Microstructure evaluation 303.2.1.2 Optical microscope 303.2.1.2 Scanning Electron Machine

(SEM)

32

3.2.3 Phase analysis 343.2.4 Density measurement 35

viii

CHAPTER 4 RESULT AND DISCUSION4.1 Observation on powder 37 4.1.1 As-received material 37

4.1.1.1 Iron Oxide 374.1.1.2 Strontium carbonate 384.1.2 Milled powder 39

4.1.3 Calcined powder 404.2 Composition Study on Strontium Ferrite 414.3 Sintered Strontium Ferrite 43

4.3.1 Final Specimens 444.3.2 Optical Observation

4.3.3 SEM observation

45

4.3.3.1 Strontium ferrite sinter at 1250oC 464.3.3.2 Strontium ferrite sinter at 1270oC 484.3.3.3 Strontium ferrite + 1% Nickel

sintered at 1270oC

49

4.3.3.4 Strontium ferrite + 2% Nickel

sintered at 1270oC

50

4.3.4 EDX microstructure4.3.3.2 Strontium ferrite sinter at 1270oC 514.3.3.3 Strontium ferrite + 1% Nickel

sintered at 1270oC

52

4.3.3.4 Strontium ferrite + 2% Nickel

sintered at 1270oC

53

4.3.5 Phase analysis 54 4. 3.6 Physical properties 56

4.3.6.1 Mass and Volume measurement 574.3.6.2 Density measurement 57

4.4 Defect on sample 58

CHAPTER 5 CONCLUSION AND RECOMMENDATION 60REFERENCES 62APPENDIX A 65APPENDIX B 67APPENDIX C 69APPENDIX D 71APPENDIX E 71

ix

LIST OF FIGURES

Figure 1.1(a) Ceramic Blocks 3

Figure 1.1(b) Ceramic Discs 3

Figure 1.1(c) Ceramic Rings 3

Figure 1.2 Generic hysteretic plot of magnetization as a

function of magnetic material. 5

Figure 2.1 Ferrite magnet 11

Figure 3.1 Processing Flow 21

Figure 3.2 Ball milling machine 23

Figure 3.2.1(a) mixing process 24

Figure 3.2.1(b) filtration 24

Figure 3.2.1(c) Powder after filtration and drying 24

Figure 3.3(a) Powder in aluminum bowl 25

Figure 3.3(b) Furnace 25

Figure 3.4 Alumina mortar 25

Figure 3.6(a) Oil strainer 26

Figure 3.5(b) Oil strainer observation by Axioscope using 26

10x magnification.

Figure 3.6 Tambling mixing 27

xi

Figure 3.7 Hydraulic Press Machine 27

Figure 3.8 Sintering profile 28

Figure 3.9 Diamond cutter 29

Figure 3.10 Figure shows steps for sample preparation. Figure 30

shows sinter specimens; (a) grinding and (b) etching

Figure 3.11(a) Optical microscope 31

Figure 3.11(b) Schematic diagram of the optical micrograph 31

Figure 3.12(a) SEM component 33

Figure 3.12(b) SEM operating 33

Figure 3.13 Electronic Densimeter 35

Figure 4.1 Figure shows SEM image for as-received Iron oxide 37

with different magnification; (a) 500x (b) 2500x.

Figure 4.2 Figure shows SEM image for as-received 38

Strontium carbonate with different magnification;

(a) 500x (b) 2500x.

Figure 4.3 Figure shows SEM image of Strontium ferrite after 39

milled with different magnification; (a) 500x (b) 2500x

Figure 4.4 SEM image of strontium ferrite powder after 40

calcined; (a) particles size (b) microstructure

with 2500 x magnification. Yellow circle indicates

powder agglomeration.

Figure 4.5 XRD patterns of strontium ferrite calcined 41

xii

at.1250oC 50C/min

Figure 4.6 Figure shows for all specimens after mounting; 44

(a) Strontium ferrite + 1% Ni sinter at 1270,

(b) Strontium ferrite sinter at 1270,

(c) Strontium ferrite + 2% Ni sinter at 1270,

(d) Strontium ferrite sinter at 1250

Figure 4.7 All figure shows the observation using optical 45

microscopy using 20 X magnification

(a) Strontium ferrite sinter at 1250

(b) Strontium ferrite sinter at 1270 oC

Figure 4.8 Figure shows SEM image for Strontium ferrite 47

sintered at 1250oC with different magnification

(a) 800x (b) 1500x (c) 5000x.

Figure 4.9 Figure shows SEM image for Strontium ferrite 48

sintered at 1270 oC with different magnification;

(a) 1500x ( b) 2500x (c) 5000x.

Figure 4.10 Figure shows SEM image for Strontium ferrite + 49

1% Nickel sintered at 1270 oC with different

magnification; (a)1500x (b) 2500x (c) 5000x.

Figure 4.11 Figure shows SEM image for Strontium ferrite + 50

2% Nickel sintered at 1270 oC with different

magnification; (a)1500x (b) 2500x (c) 5000x.

Figure 4.12 EDX result for Strontium ferrite sinter at 1270 oC 51

xiii

Figure 4.13 EDX result of Strontium ferrite + 1% Nickel 52

sintered at 1270 oC

Figure 4.14 EDX result of Strontium ferrite + 2% Nickel 53

sintered at 1270 oC

Figure 4.3.15(a) SEM Backscattered image of strontium ferrite 54

sintered at 1270 without nickel with 2500 x magnification.

Figure 4.3.15(b) SEM Backscattered image of strontium ferrite + 55

1 % Nickel sintered at 1270 oC with 2500 x magnification

Figure 4.3.15(c) SEM Backscattered image of strontium ferrite + 56

2 % Nickel sintered at 1270 oC with 2500 x magnification.

Figure 4.16(a) Specimen after sinter at 1250oC 58

Figure 4.16(b) Strontium ferrite sinter at 1270 oC 58

Figure 4.16(c) Strontium ferrite + 1% Nickel sinter at 1270oC 58

Figure 4.16(d) Strontium ferrite + 2% Nickel sinter at 1270oC 58

xiv

LIST OF TABLES

Table 1.1 Typical Magnetic and Physical Properties

of ferrite Magnet Material 5

Table 2.1 Magnetic Material Classification 7

Table 2.2 Summary of different types of magnetic behavior 9

Table 2.3 Physical Properties of hard ferrite 12

Table 2.4 Selected process parameters and their respective

levels in the present experimental design. 18

Table 4.1 Data of mass and volume 57

Table 4.2 Data of Density measurements 57

xv

LIST OF ABBREVIATIONS, SYMBOLS, NOMENCLATURES

SEM - Scanning Electron MachineEDX - Energy Dispersive X-ray AnalysisXRD - X-ray diffraction

xvi

CHAPTER 1

INTRODUCTION

1.1 Background of the project

The fabrication of the strontium ferrite magnetic material through wet

processing is doing by mixing the strontium carbonate with iron oxide powder in

wet milling. Wet milling is the grinding of materials with sufficient liquid to form

slurry. The mixing of both as received powder is doing in ball mill machine and

then calcined at certain temperature. The calcined powder is mix with the different

percentage of additives and then sintered at certain temperature. The

microstructure effect and the phase composition of the samples are evaluated using

SEM-EDX and XRD.

1.2 Problem statement

The objectives of this project are to evaluate microstructure effect and the

phase composition of the samples using SEM-EDX and XRD. The interaction of

Nickel powder as additive material in calcined material influence the grains size of the

sample after sintered. This evaluation will focus on three areas. First, microstructure

evaluation using SEM-EDX and phase analysis by XRD. Second, the percentages of

nickel powder as additives and the effect of the percentage of additives material on the

grains size of sintered samples. Lastly, the effect of different sintered temperature to

density value.

1

1.3 Objectives

The objectives of this project are:

i. To evaluate the phase composition for calcined ferrite using SEM-EDX

and XRD

ii. To evaluate microstructure effects on calcined materials.

1.4 Introduction on Magnetic material

Materials may be classified according to some of their basic magnetic properties,

particularly whether or not it is magnetic and how behave in the vicinity of an external

magnetic field. When a material is placed within a magnetic field, the magnetic forces of

the material's electrons will be affected. This effect is known as Faraday's Law of

Magnetic Induction. However, materials can react quite differently to the presence of an

external magnetic field. This reaction is dependent on a number of factors, such as the

atomic and molecular structure of the material, and the net magnetic field associated with

the atoms. The magnetic moments associated with atoms have three origins. These are

the electron orbital motion, the change in orbital caused by an external magnetic field and

the spin of the electrons. In most atoms, electrons occur in pairs. Electrons in a pair spin

in opposite directions. So, when electrons are paired together, their opposite spins cause

their magnetic fields to cancel each other. Therefore, no net magnetic field exists.

Alternately, materials with some unpaired electrons will have a net magnetic field and

will react more to an external field

1.4.1 Ceramic material

Ceramics is a singular noun referring to the art of making things out of ceramic

materials. The technology of manufacturing and usage of ceramic materials is part of the

field of ceramic engineering. Many ceramic materials are hard, porous and brittle.

Ceramic materials are usually ionic or covalently-bonded materials, and can be

crystalline or amorphous. A material held together by either type of bond will tend to

2

fracture before any plastic deformation takes place, which results in poor toughness in

these materials. Additionally, because these materials tend to be porous, the pores and

other microscopic imperfections act as stress concentrators, decreasing the toughness

further, and reducing the tensile strength. These combine to give catastrophic failures, as

opposed to the normally much more gentle failure modes of metals. These materials do

show plastic deformation. However, due to the rigid structure of the crystalline materials,

there are very few available slip systems for dislocations to move, and so they deform

very slowly. With the non-crystalline (glassy) materials, viscous flow is the dominant

source of plastic deformation, and is also very slow. It is therefore neglected in many

applications of ceramic materials.

1.4.2 Ceramic magnet

Ferrite magnets are combination between strontium, barium or plumbum

carbonate and iron oxide. They are charcoal gray in color and usually appear in the forms

of discs, rings, blocks, cylinders, and sometimes arcs for motors. Figure 1.1(a), (b) and

(c) below are the type of form of ceramic magnetic.

Figure 1.1(a): Ceramic Blocks

Figure 1.1(b): Ceramic Discs

3

Figure 1.1(c): Ceramic Rings

Sources: http://www.allmagnetics.com/ceramic.htm

Attributes of Ceramic Magnets:

• High intrinsic coercive force

• Tooling is expensive

• Least expensive material compared to alnico and rare earth magnets

• Limited to simple shapes due to manufacturing process

• Lower service temperature than alnico, greater than rare earth

• Finishing requires diamond cutting or grinding wheel

• Lower energy product than alnico and rare earth magnets

• Most common grades of ceramic are 1, 5 and 8 (1-8 possible)

• Ceramic grade 8 shown in Table 1.1 is the strongest ceramic material available.

1.4.3 Properties of magnetic material.

When ferromagnetic materials are magnetized, demagnetized, and re-magnetized,

they exhibit a hysteretic behavior illustrated as shown in Figure 1.2. Important and often

quoted features of these graphs are the saturation magnetization Ms, remanent

magnetization Mr, coercivity Hc, and saturating field Hs. With these parameters,

ferromagnetic materials can be divided into so-called soft magnetic materials (i.e., with a

small coercivity and low saturation field) and hard magnetic materials (i.e., with a large

coercivity and high saturation field).

4

Figure 1.2: Generic hysteretic plot of magnetization as a function of magnetic material.

Sources: Judy and Myung (2001)

Table 1.1: Typical Magnetic and Physical Properties of ferrite Magnet Material

Magnetic

Materials

Density

Maximum

Energy

Product

BH (max)

Residual

Induction

Br

Coercive

Force

Hc

Intrinsic

Coercive

Force

Hc

Normal

Maximum

Operating

Temp.

Curie

Temp.

lbs/in g/cm MGO Gauss Oersteds Iersteds F° C° F° C°Ceramic 1 0.177 4.9 1.05 2300 1860 3250 842* 450 842 450Ceramic 5 0.177 4.9 3.4 3800 2400 2500 842* 450 842 450

Ceramic 8 0.177 4.9 3.5 3850 2950 3050 842* 450 842 450

Sources: http://www.allmagnetics.com/ceramic.htm

All magnet materials demonstrate reversible strength loss as they approach Maximum

operating temperature.

* NOTE: Unshielded open circuit ceramic magnets should not be subjected to more than

400°F.

5

1.4.4 Application of magnetic material

Applications of ferrite Magnets are Speaker magnets, DC brushless motors,

Magnetic Resonance Imaging (MRI), Magnetos used on lawnmowers and outboard

motors, DC permanent magnet motors (used in cars), Separators (separate ferrous

material from non-ferrous), Used in magnetic assemblies designed for lifting, holding,

retrieving, and separating.

6

CHAPTER 2

LITERITURE REVIEW

2.1 Type of magnetism

Magnetic materials can be classified according to their magnetic susceptibility χ =

M / H and relative permeability μr = (χ / μ0 + 1) into several categories: ferromagnetic,

ferrimagnetic, antiferromagnetic, paramagnetic, diamagnetic, and superconducting

materials. Listed in Table 2.1 are the typical ranges of χ / μ0 for each category of

magnetic material and examples of each are identified (Parker 1989).

Table 2.1: Magnetic Material Classification

Category χ/μ0 ExamplesFerromagnetic 107 to 102 Ni, Fe, Co, NiFe, NdFeBFerrimagnetic 107 to 101 Fe3O4 Ferrite, garnetsAntiferromagnetic small MnO, NiO, FeCO3Paramagnet 10-3 to 10-6 Al, Cr, Mn, Pt, Ta, Ti, WDiamagnetic 10-6 to -10-3 -Ag, Au, C, H, Cu, Si, ZnSources from Parker(1989)

2.1.1 Diamagnetism

If the net magnetic moment of each atom in a material is zero because of mutually

canceling electronic movement within the atom, then the net flux density within the

material, due to an applied external field, is slightly less than i t would be in space

for the same field. Such a material is term diamagnetic. Examples are Cu, Bi, Pb and Ga.

Bismuth is the most pronounced diamagnetic element known (Parker 1989).

2.1.2 Paramagnetism

7