Upload
verinamaris
View
136
Download
0
Embed Size (px)
DESCRIPTION
ferit Keramik adalah bahan magnetik terdiri dari dipilih oksida dengan besi oksida. Yang paling umum komersial lembut bahan magnetik ferit spinel, Mn-Zn dan Ni-Zn ferit memiliki struktur umum AB2O4. The mangan Zinc ferit adalah disukai untuk aplikasi frekuensi yang lebih rendah kurang dari 2 MHz dimana Ni-Zn ferit lebih disukai untuk aplikasi frekuensi yang lebih tinggi umumnya transformator daya, induktor kekuasaan dan kekuasaan umum aplikasi. Struktur mikro dan sifat ferit keramik tergantung secara kritis pada kondisi pengolahan.Sifat fisik dan karakteristik sintering (Mn (1 - x) Znx) Fe2O4 telah dilakukan untuk komposisi equimolar, x = 0.5, pada tiga kondisi sintering, tiga suhu sintering (1100, 1200 & 1300 ° C) dan tiga kali sintering (1 jam, 2 jam dan 3 jam). The Xray analisis difraksi dan Scanning Electron Microscopy digunakan untuk identifikasi fase Mangan Zinc Ferrites. fisik properti, kepadatan dan penyusutan pelet sampel telah dipelajari dengan metode dimensi dan porositas dengan air mendidih Metode.
Citation preview
Material Preparation
Weighing
Wet Mixing
Binder addtion
Sintering
Evaluation
Pressing
XRD, SEM, Physical &
Magnetic properties
1100 oC, 1200
oC, 1300
oC
1hr, 2hr, 3hr
30MPa
3% PVA, 5%PEG
Drying of starting materials
MnO, ZnO, Fe2O3
Abstract—Ceramic ferrites are magnetic materials composed of
selected oxides with iron oxides. The most common commercial soft
magnetic materials are spinel ferrites, Mn-Zn and Ni-Zn ferrites
having general structure AB2O4. The Manganese-Zinc ferrite is
preferred for lower frequency applications less than 2 MHz where as
Ni-Zn ferrite is preferred for higher frequency applications generally
for power transformers, power inductors and general power
applications. The microstructure and properties of ceramic ferrites
depend critically upon the processing conditions.
The physical properties and sintering characteristics of (Mn(1-
x)Znx)Fe2O4 have been carried out for equimolar composition, x =
0.5, at three sintering conditions; three sintering temperatures (1100,
1200 & 1300 °C) and three sintering times (1 hr, 2 hr & 3 hr). The X-
ray diffraction analysis and Scanning Electron Microscopy were used
for phase identification of Manganese Zinc Ferrites. The physical
properties, density and shrinkage of the sample pellets have been
studied by dimensional method and porosity by boiling water
method.
Keywords—Powder Metallurgy, Manganese Zinc ferrite, (Mn(1-
x)Znx)Fe2O4.
I. INTRODUCTION
ODAY, magnetic materials are found in numerous
products around us- home appliances, electronic products,
automobiles, communication equipments and data processing
devices and equipments. These materials have now become a
vital part of everyday life in modern industries. The magnetic
materials used in early applications were metallic magnetic
materials. But for frequencies exceeding MHz, metals and
alloys are generally not suitable as soft magnets, as the eddy
current losses are very high. The development of ferrites since
1946 reported that electrical resistivities of ferrites over a
million times those of metals has an enormous impact in the
application of magnetic materials particularly at high
frequencies. Ferrites are used today in radio and television,
microwave and satellite communication, bubble devices,
audio, video and digital recording and as permanent magnets
[1].
Saw Mya Ni is with Metallurgical Research and Development Center, Nay
Pyi Taw, Myanmar (e-mail: [email protected]).
Kay Thi Lwin, Pro- Rector, is with Technological University (TU)
Thanlyin (e-mail: [email protected]).
II. EXPERIMENTAL PROCEDURE
The experimental procedure of Mn-Zn ferrite is shown with
the schematic flow diagram as follows:
Fig. 1 Flow Diagram of Experimental Procedure
Raw Materials Preparation
Manganese dioxide (MnO2), zinc oxide (ZnO) and ferric
oxide (Fe2O3) were used as raw materials for production of
Mn-Zn ferrite. The starting powers were technical grade of
MnO2, ZnO and Fe2O3 were 93.22%, 84.54%, and 80.33%.
MnO2 is reduced to MnO because manganese oxide (MnO) is
not easily available in local market. MnO2 (-270#) mixed with
high quality coke (-48+ 65#) under reducing atmosphere.
Powder metallurgy method was used for production of Mn-
Zn ferrite. The raw materials (MnO, ZnO, Fe2O3) were dried
and weighed in stiochiometric ratio and then wet mixed in
acetone medium for 1-2 hr to obtain thorough and
homogeneous mixing.
3% PVA solution was added as a binder for improving
compaction to the mixed powder and 5% PEG solution was
added as a lubricant to prevent powders and die friction.
The mixed powder was palletized at 30 MPa pressure by
hydraulic press machine and sintered in a high temperature
Production of Manganese-Zinc Ferrite Cores for
Electronic Applications
Saw Mya Ni, and Kay Thi Lwin
T
World Academy of Science, Engineering and Technology 22 2008
150
10 20 30 40 50 60 70
0
20
40
60
80
100
1200
400
800
1200
16000
400
800
1200
1600
Std(Mn-Zn)Fe2O4
2θ Degree
Fe2O3
Intensity
F - Unreacted Fe2O3
F FFFFFFF
1100 oC, 2hr
10 20 30 40 50 60 70
0
20
40
60
80
100
1200
400
800
1200
16000
400
800
1200
1600
Std(Mn-Zn)Fe2O4
2θ Degree
Fe2O3
Intensity
F
F - Unreacted Fe2O3
FFFFF
FFF
1100 oC, 1hr
10 20 30 40 50 60 70
0
500
1000
1500
2000
2500
30000
500
1000
1500
2000
2500
3000MnO
2θ Degree
MnO2
Intensity
10 20 30 40 50 60 70
0
20
40
60
80
100
120
0
400
800
1200
1600
Std(Mn-Zn)Fe2O4
Intensity
2θ Degree
1100 oC, 3hr
muffle furnace at three different sintering temperature of
1100°C, 1200°C and 1300°C and three sintering time 1hr, 2hr
and 3hr respectively in order to achieve desirable physical
properties and low porosity.
The sintered pellets were characterized by X- ray diffraction
analysis and scanning electron microscopy for phase
identification. The physical properties, the density and
shrinkage were measured by dimensional method. The
porosity was measured by boiling water method.
The electrical and magnetic properties; resistivity, relative
permeability, magnetization, coercive force, remanence,
magnetic flux density, magnetic field intensity and B-H
characteristics were also measured.
III. RESULTS AND DISCUSSION
X-ray diffraction analysis was used for characterization of
phases. MnO phase was confirmed by X- ray diffraction
analysis as shown in Fig. 2.
Fig. 2 XRD Pattern of MnO Compared with that of MnO2 Powder
Pattern
Fig. 3 XRD Pattern of Mn-Zn Ferrite Sintered at 1100oC for 1hr
Compared with that of Standard JCPDF Data and Starting Powder
Pattern
The following graphs are the XRD patterns of manganese
zinc ferrite at different sintering times and temperatures. Fig. 3
shows X- ray diffraction analysis of Mn-Zn ferrite sintered at
1100°C for 1hr. Unreacted Fe2O3 phases were observed at that
sintering condition showing this sintering temperature and time
is not sufficient.
Fig. 4 XRD Pattern of Mn-Zn Ferrite Sintered at 1100o C for 2hr
Compared with that of Standard JCPDF data and Starting Powder
Pattern
Fig. 4 shows X- ray diffraction analysis of Mn-Zn ferrite
sintered at 1100°C for 2hr. At this sintering temperature and
time, unreacted Fe2O3 phases were also observed. This shows
that the sintering 1100ºC and sintering time 2hrs was also not
sufficient.
Fig. 5 XRD Pattern of Manganese Zinc Ferrite Sintered at
1100o C for 3hr Compared with that of Standard JCPDF data
Fig. 5 shows X-ray diffraction analysis of Mn-Zn ferrite
sintered at 1100°C for 3hr. At this sintering temperature and
sintering time, all the starting powders were completely
reacted and spinel phases formation was confirmed.
World Academy of Science, Engineering and Technology 22 2008
151
10 20 30 40 50 60 70
0204060801001200
400800120016002000
0
400800
12001600
20000
400800120016002000
Std(Mn-Zn)Fe2O
4
2θ Degree
1200 oC, 1hr
1200 oC, 2hr
Intensity
1200 oC, 3hr
Fig. 6 XRD Pattern of Mn-Zn Ferrite Sintered at 1200oC for 1hr,
2hr & 3hr Compared with that of Standard JCPDF Data
Fig. 7 XRD Pattern of Mn-Zn Ferrite Sintered at 1300o C for 1hr,
2hr & 3hr Compared with that of Standard JCPDF Data
Fig. 6 shows XRD pattern of manganese zinc ferrite sintered
at constant temperature1200°C by varying the sintering time
for 1hr, 2hr and 3hr. At this temperature, spinel phases were
confirmed for all the sintering time.
Fig. 7 shows XRD pattern of Mn-Zn ferrite sintered at
constant temperature, 1300°C by varying sintering time for
1hr, 2hr and 3hr. The optimum sintering condition for Mn-Zn
ferrite was observed at 1300°C for 3hr from the nature of the
peak of X- Ray pattern.
Fig. 8 Composite XRD Pattern of Mn-Zn Ferrite Sintered at
Optimum Sintering Condition of 1300ºC for 3 hr
Fig. 8 shows the composite XRD pattern of (Mn(1-
x)Zn(x))Fe2O4 for x = 0.5 composition at optimum sintering
condition of 1300ºC and sintering time 3hr. The ferrite pattern
of Mn-Zn ferrite indicates the consistency with that of pure
end member Mn ferrite and Zn ferrite spinels.
Physical Properties
The results of the measurement of physical properties of
Mn-Zn ferrite are presented in Figs. 9 to 12.
The graphs shown in Figure indicate the increasing of the
density and shrinkage of the sintered pellets with increasing of
the sintering conditions; times and temperatures.
But the porosity decreases as the sintering condition
increases as shown in Fig. 12. All these graphs confirm that the
physical properties increase with increasing of the sintering
time and temperature.
The maximum sintering temperature of 1300°C and 3hr
sintering time gives the 94% of theoretical density for (Mn(1-
x)Zn(x))Fe2O4, x = 0.5.
10 20 30 40 50 60 70
0204060801001200
400
800
1200
1600
20000
400
800
1200
1600
20000
400
800
1200
1600
2000
Std(Mn-Zn)Fe204
2θθθθ Degree
1300 oC, 1hr
1300 oC, 2hr
Intensity
1300 oC, 3hr
10 20 30 40 50 60 70
0
750
1500
2250
3000
0
750
1500
2250
3000
0
750
1500
2250
3000
0
750
1500
2250
3000
0
750
1500
2250
3000
Degree (2θ)
X=0
X=0.25
X=0.5
Intensity
X=0.75
(Mn(1-x)
Zn(x))Fe
2O
4
X=1
World Academy of Science, Engineering and Technology 22 2008
152
Fig. 9 Variation of Density with Different Sintering Condition for
Mn-Zn Ferrite
Fig. 10 Variation of Shrinkage in Diameter of Sintered Pellet at
Different Sintering Condition
Fig. 11 Variation of Shrinkage in Thickness of Sintered Pellets at
Different Sintering Condition
Fig. 12 Variation of Porosity with Different Condition for Mn-Zn
Ferrite
Spinel Phase Identification by Scanning Electron
Microscopy
The scanning electron micrographs of manganese zinc
ferrite were given in following figures.
1100 1150 1200 1250 13003.7
3.8
3.9
4.0
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
5.0
Theorectical density - 5.009 g/cm3
Density, g/cm
3
3hr
2hr
1hr
Sintering Temperature, oC
1hr
2hr
3hr
1100 1150 1200 1250 1300
1.4
1.5
1.6
1.7
1.8
1.9
2.0
2.1
ds - Diameter of sintered pellet
dg - Diameter of green pellet
Shrinkage in D
iameter, m
m, (d
g-d
s)
3hr
2hr
1hr
Sintering Temperature,oC
1hr
2hr
3hr
1100 1150 1200 1250 1300
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3hr
2hr
1hr
% Porosity
Sintering Temperature, oC
1hr
2hr
3hr
1100 1150 1200 1250 1300
0.10
0.15
0.20
0.25
0.30
0.35
0.40
Sintering Temperature,oC
3hr
2hr
1hrtg - Thickness of green pellet
ts - Thickness of sintered pellet
Shrinkage in Thickness, mm, t g- t s
1hr
2hr
3hr
World Academy of Science, Engineering and Technology 22 2008
153
Fig. 13 SEM Micrograph of Mn-Zn Ferrite Sintered at 1200oC & 3hr
with 10µ Scale
Fig. 13 shows scanning electron micrograph of manganese
zinc ferrite sintered at 1200°C & 3hr with 10µ scale. Some
pores can be seen this condition. The average grain size is
3.2µm.
Fig. 14 SEM Micrograph of Mn-Zn Ferrite Sintered at 1250oC &
2hr with 10µ Scale
Fig. 14 shows scanning electron micrograph of manganese
zinc ferrite sintered at 1250°C and 2hrs with 10µ scale. The
average grain size is 4µm. Porosity decreases with increasing
sintering time and temperature. The average grain size is 4µm.
Fig. 15 SEM Micrograph of Mn-Zn Ferrite Sintered at 1250oC & 2hr
with 5µ Scale
Fig. 15 shows scanning electron micrograph of manganese
zinc ferrite sintered at 1250°C and 2hrs with 5µ scale just to
enlarge the surface morphology.
Fig. 16 SEM Micrograph of Mn-Zn Ferrite Sintered at 1300oC &
3hr with 10µ Scale
Fig. 16 shows scanning electron micrograph of manganese
zinc ferrite sintered at 1300°C and 3hrs with 10µ scale.
Average grain size is 6.9µm. By increasing sintering time and
temperature, grain growth increases and the average grain size
increases from 3.2µm in Fig. 13 to 6.9µm in Fig. 16.
World Academy of Science, Engineering and Technology 22 2008
154
Magnetic Properties
Fig. 17 The Variation of Electrical Resistivities of Mn-Zn Ferrite
Depending on the Zn Addition
The variation of the electrical resistivity (ρ) with increasing
the composition of zinc ferrite, at room temperature, is
represented in Fig. 17. It is obvious that the electrical
resistivity is decreased rapidly by adding zinc ferrite.
Fig. 18 Variation in Relative Permeability with Different
Compositionfor Mn-Zn Ferrite Spinel
The composition dependence of the relative permeability at
room temperature is represented in Fig. 18. Maximum relative
permeability of (Mn(1-Zn(x))Fe2O4 was observed at ZnFe2O4
composition 0.25.
The typical hysteresis loop of Mn-Zn ferrite using the
measured data with oscilloscope is presented in Fig. 19. The
magnetic properties of manganese zinc ferrite was observed
high permeability, small coercive field, small remanence, small
hysteresis loop, rapid response to high-frequency magnetic
fields and low electrical resistivity.
Fig. 19 Typical Hysteresis Loop of Mn-Zn Ferrite
IV. CONCLUSION
The sintering characteristics, physical properties, X-ray
diffraction analysis and scanning electron microscopy as phase
characterization techniques were studied. The fabrication of
Mn-Zn ferrites (Mn(1-x)Zn(x))Fe2O4 have been studied at
different sintering conditions. The optimum sintering condition
was obtained at 1300ºC and 3h. The density and shrinkage of
the sintered pellets are increased with the increasing of
sintering time and temperature. Maximum relative
permeability of (Mn(1-x)Zn(x))Fe2O4 was observed at ZnFe2O4
composition 0.25. The porosity was decreased with increasing
of sintering time and temperature. The electrical resistivity of
MnFe2O4 is decreased rapidly by adding zinc ferrite. The
magnetic properties of (Mn-Zn) Fe2O4 are more or less in the
range of standard value. The nature of the B-H curve also
agrees with the nature of the standard B-H characteristic of
(Mn-Zn)Fe2O4.
REFERENCES
[1] Heck, C. 1974. Magnetic Materials and their Applications. London:
Butterworths
[2] Donald R. Askeland. 1994. The Science and Engineering of
Materials. 3rd ed.Bostom: PWS Publishing Company.
[3] William .D.Callister, Jr. 1994. Materials Science and Engineering.
[4] Carl A.Keyser. 1986. Materials Science in Engineering
[5] Roberts. J. 1960. High Frequency Application of Ferrites
[6] David Jiles, 1998. Introduction to Magnetism and Magnetic Materials.
2nd ed.U.S.A.: A CRC Press Company.
[7] By Thomas G. Reynolds. No Date. Ferrites.
[8] Kingery. W. D., Bowen. H.K, Uhlmann D.R. 1976. Introduction to
Ceramics.
0.0 0.2 0.4 0.6 0.8 1.0
0
2
4
6
8
10 Sintering temperature at 1300C for 3hr
(Mn(1-x)
Zn(x))Fe
2O
ZnFe2O
4MnFe
2O
4
Electrical Resistivity x 102 (
Ω m
)
XZnFe
2O
4
0.0 0.2 0.4 0.6 0.8 1.0
0.0
0.5
1.0
1.5
2.0
2.5
sintering temperature at 1300oC for 3hr
(Mn(1-x)
Zn(x))Fe
2O
ZnFe2O
4MnFe
2O
4
Relative Perm
eability (
µr)
XZnFe
2O
4
World Academy of Science, Engineering and Technology 22 2008
155