Structure and Hardness Characteristics of 50 Cr-50AT Coating Prepared by Mechanical Alloying Technique: Effect of Heat Treatment Temperature
TEKNOLOGI INDONESIA
ISSN: 0126-1533
Akreditasi: 590/AU31P2Ml-LIPII0312015
EDlTORSIREFEREES
1. Tarzan Sembi ring. Prof. Dr. .
Microbiology. Biochemistry & Environmental Technology
2. Tjandra Setiadi. Prof. Dr.
Biotechnology & Chemical Engineering
3. Totok M.S. Soegandl. Prof. Dr.
Physics and Electronics
4. TImbangen Sembiring. Prof. Dr.
Material Science and Kristallography
5. Tigor Nauli
Theory and Computational Chemistry
6. Supartono 5oediatno
Communication and Informatic Technology
7. Soenarto Goenadi. Dr.DEA.
Hydrology and Environmental Science
S. Soemanto Imam Khasani. Prof. Dr.
Chemical Analysis and Safety
9. Rudi Subagja. Dr.
Extractive Metalurgy
10. Masno Ginting. Prof. Dr.
Solid State Physics. Electronica and Mechanis
11. Mochamad !chwan. Dr.-Ing
Mechanical Engineering. Energy Conversion
and Material Science
12. Linar Z. Udin. Dr.
Biochemistry
13. L Broto 5. Kardono. Prof. Dr.
Pharmacology and Biochemistry of Drugs
14. Kreshna Amurwabumi. Prof. Dr.
Magnetics. Non Destructive Testing Appropiate
Technology
15. Kapti Rahayu. Prof. Dr.
Microbiology and Food Technology
16. Johny Wahyuadi. Prof. Dr.
Metalurgy and Corrosion
17. Goib Wiranto. Dr.
Microelectronic and Microengineering
lS. Fauzan Ali, Dr.
Limnology
19. Fatimah Z.S. Padmadinata. Dr.
Quality Management and System
20. Ellin Yulinah Sukandar, Prof. Dr.
Pharmacology and Toxicology
21. Elan Djaelani
Electronic Engineering
22. Edy Supriyanto. Dr.
Semiconductor and Nanotechnology
23. Bambang Sunarko. Dr.rer.nat
Microbiology
24. Agus Maryono. Dr.-Ing.
Civil and Environmental Engineering
25. Adiseno. Dr.
Information and Communication
26. Adrin Tohari, Dr.
Geoteehnology
Environmental Working Group-UP!
Departemen Chemical Engineering Bandung Institute of
Technology
Research Center for Electronics and Telecomunication-UPI
University of North Sumatra
Research Center for Informatics
Faculty of Electronic Engineering
Christian Maranatha University. Bandung
Faculty of Agricultural Technology Gadjah Mada university
Research Center for Chemistry-UP!
Research Center for Metalurgy-UP!
Research Center for Physics-UP!
Research Center for Electrical Power and Mechatronies-UPI
Research Center for Chemistry-UP!
Research Center for Chemistry UPI
Research Center for Physlcs-UPI
Faculty of Agultural Gadjah Mada University
Departement of Material and Metalurgy
University of Indonesia
Research Center for Electronics and Telecomunication-UPI
Research Center for Limnology-UP!
Research Center for Quality System and
Testing Technology-UP!
Bandung Institute of Technology
Research Center for Informatics-UP!
University of Jember
Research Center for Biology-UP!
Faculty of Civil Engineering Gadjah Mada University
Research Center for Electronics and Telecomunication-UP!
Reserach Center for Geotechnology-UP!
SIT
No.I046/SKlDi\ien PPG/SIT/ 1986
LIPI Press
Kala kUllci: 50Cr-50AI, pemaduan mekanik. heat treamn~
INTRODUCTION
The low carbon steels have been widely used for
many structural applications since they are cheap
to produce and good mechanical properties as
well. However, the application of the materials
156
struktur. kekerasan.
tends to limit due to their poor resistance against
oxidation and corrosion at high temperature.
Thus. their properties need to be improved.II-'l ln
general, there are two methods that can be applied
to improve resistance to oxidation, corrosion, and
TOlD Sudiro, Perdamean Sebayang. Didik Aryanlo. April Imelda J.H.. and Kerista Sebayang I StrucTUre and Hardness ,..
wear of metals and aUoys as alloy enrichment or
coating. When used to improve the oxidation and
corrosion resistance, however, the first approach
often leads to reducing the inechanical properties
of the alloy. Accordingly, in order to maintain
the mechanical properties of alloy steel, coating
deposition is commonly used to improve the
resistance of alloy against oxidation, corrosion,
and wear."J
It was noteworthy that Cr and AI are important elements for improving the oxidation
and corrosion resistance of alloy and coating
because they can act as reservoir for the formation of protective oxide scale ofCr,0 3andAJ,O"
respectively, to retard the diffilsion of oxygen to
the alloy substrates as Fe and Ni-based alloys.
[HI The microstructure, mechanical properties,
and high temperature oxidation and corrosion
resistance ofCT-based coating as NiCr,r6J FeCr{7J
and AI-based coating as NiAI,£2-l· 8-9J FeAlp·IOJ
TiAl['· II-I'J were studied and discussed. The high
temperature oxidation and corrosion resistance
of NiCr-CrAI has been studied by Ren et aI.[1l]
However, the report on CrAI coating is rare. In
general, there are some requirements that must
be met before the material is tested at high temperatures, i.e. coating uniformity and coating!
substrate compatibility. Accordingly, clarification
of coating before high temperature oxidation test
is particularly important for coating development.
Currently, mechanical alloying technique was
utilized to reduce the powder size from micro to
nano scale. This technique was also used to deposit
Fe-AI,[IJ NiAI,['-3J and Ti-AI coatings[II-I'J on low
carbon steel. The basic principle of this technique
for deposition of coating is that the collision of
ball and powder on surface of the substrate during
mechanical alloying process results in the deposition of coating powder on steel substrate.l'-3. 12J
In order to obtain a uniform coating structure
and enhance the bonding of coating-substrate,
further process, i.e. annealing or heat treatment
is required. In writers' previous work, they have
prepared varying composition of Cr-AI coatings
as 1aOAl, SOCrSOAl, 87 .SCr 12.SAI, 100Cr and
heat treated each composition at 800"C to study
the structure of the coating. (I4J In the present
study, the writers focus on investigating the ef-
fect of annealing or heat treatment temperature
on the structure and hardness characteristic of
SOCr-SOAI coating. The results are presented and
discussed in this paper.
MATERIALS AND METHODS
The samples and coatings were prepared using
the same method as presented in writers' previous study.["J The commercial low carbon steel
was used as substrate. The steel plate was cut to
rectangular specimens with a dimension of about
10 x 8 x 3 mm. Before coating, the surface of
the specimen was poLished mechanically using
SiC papers for upto No. 1200 and ultrasonically
cleaned in an ethanol solution.
For deposition of the coating, Cr and Al
powders with nominal composition of 50:50
at% and grain size of about 75 11m and 300 11m,
respectively, were used as starting material. The
powders were mixed by high speed shaker mill
for 2 h in steel chamber with steel balls to powder
ratio of 10 to I. Three specimens were then put
and charged into the vial with approximate volume of70 ml. This mechanical alloying process
was carried out for I h in ambient air atmosphere.
The collisions of steel balls and powder on the
surface oflow carhon steel lead to d.eposition of
coating powder on the steel surface. The coated
sample was heat treated in a vacuum of5.6 Pa at
four different temperatures of 600, 700, 800, and
900°C for 2h, separately. Hereafter, the specimens
were cooled down to room temperature.
The phase compositions of the coating before and after heat treatment were analyzed by
X-ray di1Iraction (SmartLab Rigaku) with Cu
Ka radiation at 40kV and 30mA. The coating
morphologies were characterized by means of
scanning electron microscope equipped with
energy dispersive X-ray spectrometer (SEM
Hitachi SU 3500-EDX).
The hardness of Cr-Al coatings before and
after heat treatment was measured across the
cross-sectional of the coating using a Vickers
hardness technique (Leco Microhardness Tester
LM I OOAD. The specimen indentation was carried out under load of 500 kgf for 15 s.
157
Teknologi [ndonesia 38 (3) 2015
.1
,.
- •
'f
".,
•
*~
l
$
,
... - - -.
..
:,
-=!
.:
~
-.
"
-I:
ld)
II
•
•
•
•
•
lei
•I
~
..
,J,__.....-'._ _ _ _
,1,_ ...+
".,..
~
-:: ...#au: .. '. 4;e«:
I'" . .! 4
~.,
' \Dgl~
(') f l!
VAl
¢ Ct
feAl
· it
t gs
1
p'
~
t!
18 (~)
.... AltCts • AICI,
•
Al ~ O .
Figure 1. X-ray Diffraction Patterns of Substrate (a), 50Cr-50Al Coatings Before (b) and After Heat Treatment at
Temperatures of (c) 600°C, (d) 700°C, (e) 800°C, and (f) 900°C for 2 h
158
Toto Slldiro. Perdamean Sebayang, Didik Aryanto. April Jmelda J.H. . and Kerisla Sebayallg I Strucmre and Hardlless ...
RESULTS AND DISCUSSIONS
Phase composition of the coating
X-ray diffraction patterns of 50Cr-50AI coatings before and after heat treatment at elevated
temperatures of 600, 700, 800, and 900°C for 2
bare sbown in Figure 1.
According to result ofXRD cbaracterization,
low carbon steel is mainly composed of Fe-phase
(Figure l a). As shown in Figure I (b), before beat
treatment, X-ray diffraction analysis shows the Cr
and Al diffractions in the coating. This indicates
that Cr and Al were successfully deposited on the
;teel substrate and mechanical alloying did not
lead to the formation ofCr-AI intennetallic com~oun
ds.
Meanwbile, after heat treatment (Figs.
l(c)-(1)), intermetallie phases as AIBCr" AlCr"
FeAI, Fe,AI phases are fonned, depending on the
leat treatment temperature. At 600 and 700°C,
K-ray diffraction still observes the reflection of
::r. The Cr diffraction peak intensity decreases
Nith increase in heat treatment temperature. The
:r diffraction is not found after heat treatment at
temperature of 800 and 900°C. At 900°C, new
phases as FeAl and Fe~
are detected. The results
ofXRD characterization also reveal that as heat
treatment temperature increases, the diffraction
peak of AlCr, increases and AlaCr, decreases.
However, after heat treatment at 900"C for 2 h,
AI,0, reflection is detected. This suggests that Al
is oxidized to form Al,O,. A different in the pbase
of composition of the coating before and after
heat treatment may affect the coating hardness.
Cross-section micrograph of the coatings
In this study, the writers carried out tbe erosssectional observation of the coating, before and
after beat treatment at elevated temperatures
of 800 and 900"C. The typical cross-sectional
micrographs and corresponding EDX element
distribution maps ofCr,AI and Fe of coated samples before and after heat treatment at elevated
temperatures of 800 and 900· C are shown in
Figure 2 (a), (b) and (c), respectively.
Igure 2. Cross-sectional Images of 5OCr-50AI Coatings and Corresponding EDX Element Distribution Maps of
'r. AI and Fe of Coated Low Carbon Steel Before
ISSN: 0126-1533
Akreditasi: 590/AU31P2Ml-LIPII0312015
EDlTORSIREFEREES
1. Tarzan Sembi ring. Prof. Dr. .
Microbiology. Biochemistry & Environmental Technology
2. Tjandra Setiadi. Prof. Dr.
Biotechnology & Chemical Engineering
3. Totok M.S. Soegandl. Prof. Dr.
Physics and Electronics
4. TImbangen Sembiring. Prof. Dr.
Material Science and Kristallography
5. Tigor Nauli
Theory and Computational Chemistry
6. Supartono 5oediatno
Communication and Informatic Technology
7. Soenarto Goenadi. Dr.DEA.
Hydrology and Environmental Science
S. Soemanto Imam Khasani. Prof. Dr.
Chemical Analysis and Safety
9. Rudi Subagja. Dr.
Extractive Metalurgy
10. Masno Ginting. Prof. Dr.
Solid State Physics. Electronica and Mechanis
11. Mochamad !chwan. Dr.-Ing
Mechanical Engineering. Energy Conversion
and Material Science
12. Linar Z. Udin. Dr.
Biochemistry
13. L Broto 5. Kardono. Prof. Dr.
Pharmacology and Biochemistry of Drugs
14. Kreshna Amurwabumi. Prof. Dr.
Magnetics. Non Destructive Testing Appropiate
Technology
15. Kapti Rahayu. Prof. Dr.
Microbiology and Food Technology
16. Johny Wahyuadi. Prof. Dr.
Metalurgy and Corrosion
17. Goib Wiranto. Dr.
Microelectronic and Microengineering
lS. Fauzan Ali, Dr.
Limnology
19. Fatimah Z.S. Padmadinata. Dr.
Quality Management and System
20. Ellin Yulinah Sukandar, Prof. Dr.
Pharmacology and Toxicology
21. Elan Djaelani
Electronic Engineering
22. Edy Supriyanto. Dr.
Semiconductor and Nanotechnology
23. Bambang Sunarko. Dr.rer.nat
Microbiology
24. Agus Maryono. Dr.-Ing.
Civil and Environmental Engineering
25. Adiseno. Dr.
Information and Communication
26. Adrin Tohari, Dr.
Geoteehnology
Environmental Working Group-UP!
Departemen Chemical Engineering Bandung Institute of
Technology
Research Center for Electronics and Telecomunication-UPI
University of North Sumatra
Research Center for Informatics
Faculty of Electronic Engineering
Christian Maranatha University. Bandung
Faculty of Agricultural Technology Gadjah Mada university
Research Center for Chemistry-UP!
Research Center for Metalurgy-UP!
Research Center for Physics-UP!
Research Center for Electrical Power and Mechatronies-UPI
Research Center for Chemistry-UP!
Research Center for Chemistry UPI
Research Center for Physlcs-UPI
Faculty of Agultural Gadjah Mada University
Departement of Material and Metalurgy
University of Indonesia
Research Center for Electronics and Telecomunication-UPI
Research Center for Limnology-UP!
Research Center for Quality System and
Testing Technology-UP!
Bandung Institute of Technology
Research Center for Informatics-UP!
University of Jember
Research Center for Biology-UP!
Faculty of Civil Engineering Gadjah Mada University
Research Center for Electronics and Telecomunication-UP!
Reserach Center for Geotechnology-UP!
SIT
No.I046/SKlDi\ien PPG/SIT/ 1986
LIPI Press
Kala kUllci: 50Cr-50AI, pemaduan mekanik. heat treamn~
INTRODUCTION
The low carbon steels have been widely used for
many structural applications since they are cheap
to produce and good mechanical properties as
well. However, the application of the materials
156
struktur. kekerasan.
tends to limit due to their poor resistance against
oxidation and corrosion at high temperature.
Thus. their properties need to be improved.II-'l ln
general, there are two methods that can be applied
to improve resistance to oxidation, corrosion, and
TOlD Sudiro, Perdamean Sebayang. Didik Aryanlo. April Imelda J.H.. and Kerista Sebayang I StrucTUre and Hardness ,..
wear of metals and aUoys as alloy enrichment or
coating. When used to improve the oxidation and
corrosion resistance, however, the first approach
often leads to reducing the inechanical properties
of the alloy. Accordingly, in order to maintain
the mechanical properties of alloy steel, coating
deposition is commonly used to improve the
resistance of alloy against oxidation, corrosion,
and wear."J
It was noteworthy that Cr and AI are important elements for improving the oxidation
and corrosion resistance of alloy and coating
because they can act as reservoir for the formation of protective oxide scale ofCr,0 3andAJ,O"
respectively, to retard the diffilsion of oxygen to
the alloy substrates as Fe and Ni-based alloys.
[HI The microstructure, mechanical properties,
and high temperature oxidation and corrosion
resistance ofCT-based coating as NiCr,r6J FeCr{7J
and AI-based coating as NiAI,£2-l· 8-9J FeAlp·IOJ
TiAl['· II-I'J were studied and discussed. The high
temperature oxidation and corrosion resistance
of NiCr-CrAI has been studied by Ren et aI.[1l]
However, the report on CrAI coating is rare. In
general, there are some requirements that must
be met before the material is tested at high temperatures, i.e. coating uniformity and coating!
substrate compatibility. Accordingly, clarification
of coating before high temperature oxidation test
is particularly important for coating development.
Currently, mechanical alloying technique was
utilized to reduce the powder size from micro to
nano scale. This technique was also used to deposit
Fe-AI,[IJ NiAI,['-3J and Ti-AI coatings[II-I'J on low
carbon steel. The basic principle of this technique
for deposition of coating is that the collision of
ball and powder on surface of the substrate during
mechanical alloying process results in the deposition of coating powder on steel substrate.l'-3. 12J
In order to obtain a uniform coating structure
and enhance the bonding of coating-substrate,
further process, i.e. annealing or heat treatment
is required. In writers' previous work, they have
prepared varying composition of Cr-AI coatings
as 1aOAl, SOCrSOAl, 87 .SCr 12.SAI, 100Cr and
heat treated each composition at 800"C to study
the structure of the coating. (I4J In the present
study, the writers focus on investigating the ef-
fect of annealing or heat treatment temperature
on the structure and hardness characteristic of
SOCr-SOAI coating. The results are presented and
discussed in this paper.
MATERIALS AND METHODS
The samples and coatings were prepared using
the same method as presented in writers' previous study.["J The commercial low carbon steel
was used as substrate. The steel plate was cut to
rectangular specimens with a dimension of about
10 x 8 x 3 mm. Before coating, the surface of
the specimen was poLished mechanically using
SiC papers for upto No. 1200 and ultrasonically
cleaned in an ethanol solution.
For deposition of the coating, Cr and Al
powders with nominal composition of 50:50
at% and grain size of about 75 11m and 300 11m,
respectively, were used as starting material. The
powders were mixed by high speed shaker mill
for 2 h in steel chamber with steel balls to powder
ratio of 10 to I. Three specimens were then put
and charged into the vial with approximate volume of70 ml. This mechanical alloying process
was carried out for I h in ambient air atmosphere.
The collisions of steel balls and powder on the
surface oflow carhon steel lead to d.eposition of
coating powder on the steel surface. The coated
sample was heat treated in a vacuum of5.6 Pa at
four different temperatures of 600, 700, 800, and
900°C for 2h, separately. Hereafter, the specimens
were cooled down to room temperature.
The phase compositions of the coating before and after heat treatment were analyzed by
X-ray di1Iraction (SmartLab Rigaku) with Cu
Ka radiation at 40kV and 30mA. The coating
morphologies were characterized by means of
scanning electron microscope equipped with
energy dispersive X-ray spectrometer (SEM
Hitachi SU 3500-EDX).
The hardness of Cr-Al coatings before and
after heat treatment was measured across the
cross-sectional of the coating using a Vickers
hardness technique (Leco Microhardness Tester
LM I OOAD. The specimen indentation was carried out under load of 500 kgf for 15 s.
157
Teknologi [ndonesia 38 (3) 2015
.1
,.
- •
'f
".,
•
*~
l
$
,
... - - -.
..
:,
-=!
.:
~
-.
"
-I:
ld)
II
•
•
•
•
•
lei
•I
~
..
,J,__.....-'._ _ _ _
,1,_ ...+
".,..
~
-:: ...#au: .. '. 4;e«:
I'" . .! 4
~.,
' \Dgl~
(') f l!
VAl
¢ Ct
feAl
· it
t gs
1
p'
~
t!
18 (~)
.... AltCts • AICI,
•
Al ~ O .
Figure 1. X-ray Diffraction Patterns of Substrate (a), 50Cr-50Al Coatings Before (b) and After Heat Treatment at
Temperatures of (c) 600°C, (d) 700°C, (e) 800°C, and (f) 900°C for 2 h
158
Toto Slldiro. Perdamean Sebayang, Didik Aryanto. April Jmelda J.H. . and Kerisla Sebayallg I Strucmre and Hardlless ...
RESULTS AND DISCUSSIONS
Phase composition of the coating
X-ray diffraction patterns of 50Cr-50AI coatings before and after heat treatment at elevated
temperatures of 600, 700, 800, and 900°C for 2
bare sbown in Figure 1.
According to result ofXRD cbaracterization,
low carbon steel is mainly composed of Fe-phase
(Figure l a). As shown in Figure I (b), before beat
treatment, X-ray diffraction analysis shows the Cr
and Al diffractions in the coating. This indicates
that Cr and Al were successfully deposited on the
;teel substrate and mechanical alloying did not
lead to the formation ofCr-AI intennetallic com~oun
ds.
Meanwbile, after heat treatment (Figs.
l(c)-(1)), intermetallie phases as AIBCr" AlCr"
FeAI, Fe,AI phases are fonned, depending on the
leat treatment temperature. At 600 and 700°C,
K-ray diffraction still observes the reflection of
::r. The Cr diffraction peak intensity decreases
Nith increase in heat treatment temperature. The
:r diffraction is not found after heat treatment at
temperature of 800 and 900°C. At 900°C, new
phases as FeAl and Fe~
are detected. The results
ofXRD characterization also reveal that as heat
treatment temperature increases, the diffraction
peak of AlCr, increases and AlaCr, decreases.
However, after heat treatment at 900"C for 2 h,
AI,0, reflection is detected. This suggests that Al
is oxidized to form Al,O,. A different in the pbase
of composition of the coating before and after
heat treatment may affect the coating hardness.
Cross-section micrograph of the coatings
In this study, the writers carried out tbe erosssectional observation of the coating, before and
after beat treatment at elevated temperatures
of 800 and 900"C. The typical cross-sectional
micrographs and corresponding EDX element
distribution maps ofCr,AI and Fe of coated samples before and after heat treatment at elevated
temperatures of 800 and 900· C are shown in
Figure 2 (a), (b) and (c), respectively.
Igure 2. Cross-sectional Images of 5OCr-50AI Coatings and Corresponding EDX Element Distribution Maps of
'r. AI and Fe of Coated Low Carbon Steel Before