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nitrogen stainless steel, Acta Metall. Sin., 52 (2016), 233–240,
doi:10.11900/0412.1961.2015.00282
16 A. Al-Hashem, P. G. Cacere, A. Abdullah, H. M. Shalaby, Cavitation
corrosion of duplex stainless steel in seawater, Corrosion, 53 (1997),
103–113, doi:10.5006/1.3280438
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erosion and corrosion of various engineering alloys in 3.5% NaCl
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tation on corrosion behavior of 20SiMn low-alloy steel in 3% sodium
chloride solution, Corrosion, 59 (2003), 597–605, doi:10.5006/
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22 B. Vyas. I. L.H. Hansson, The cavitation erosion-corrosion of
stainless steel, Corro. Sci., 30 (1990), 761–770, doi:10.1016/0010-
938X(90)90001-L
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25 S. Hong, Y. P. Wu, J. Zhang, Y. G. Zheng, J. Lin, Synergistic effect
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Y. X. QIAO et al.: CAVITATION EROSION PROPERTIES OF A NICKEL-FREE HIGH-NITROGEN Fe-Cr-Mn-N STAINLESS STEEL
938 Materiali in tehnologije / Materials and technology 51 (2017) 6, 933–938
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967–2017) – 50 LET/50 YEARS
D. R. PONNUSAMY RAJARATHNAM, M. JAYARAMAN: INVESTIGATION OF THE WEAR BEHAVIOUR OF AN AISI 1040 ...
939–944
INVESTIGATION OF THE WEAR BEHAVIOUR OF AN AISI 1040
FORGED STEEL SHAFT WITH PLASMA-SPRAY
CERAMIC-OXIDE COATINGS FOR SUGAR-CANE MILLS
RAZISKAVA OBRABE AISI 1040 KOVANE JEKLENE GREDI S
KERAMI^NIMI OKSIDNIMI PREVLEKAMI ZA MLINE ZA
MLETJE SLADKORNEGA TRSA
Duraisamy Revathi Ponnusamy Rajarathnam1, Murugesan Jayaraman2
1Paavai Engineering College, Department of Mechanical Engineering, Namakkal District, India
2Velalar College of Engineering and Technology, Department of Mechanical Engineering, Erode District, India
drprajamalathi@yahoo.co.in
Prejem rokopisa – received: 2017-03-27; sprejem za objavo – accepted for publication: 2017-05-19
doi:10.17222/mit.2017.035
In this investigation, ceramic oxide powders, alumina, titania, chromia, alumina-titania, alumina-chromia and titania-chromia,
were coated for a thickness of 200 μm on an AISI 1040 forged steel substrate by means of an atmospheric plasma spraying
method. Ni-Cr was used as an intermediate bond coat of thickness 20 μm over the substrate to improve the coating adhesion.
Pin-on-disc apparatus was employed for a dry wear test as per the American Society for Testing and Materials G99 standards for
a constant load of 10 N, at different sliding distances of 1000 m, 2000 m and 3000 m, respectively. The investigation shows that
the microstructure, coating thickness, porosity, surface roughness and hardness influence the wear rate. Before and after the
wear tests, surface roughness measurements were carried out by using a talysurf instrument on the specimens. It is shown that
the highest value (20.89 μm) was obtained for the coating of alumina-titania. The practical results show that the pure chromia
coated specimen has a very good wear-resistance property compared to the ceramic oxides. This suggests that surface coating
with pure chromia on the top mill roll shaft of sugar industries enhanced the wear resistance.
Keywords: alumina, titania, chromia, atmospheric plasma spray, pin-on-disc, wear, Talysurf profilometer
V raziskavi so bili oksidni pra{ki: glinica, titan, krom, aluminijev oksid, aluminij-krom, prevle~eni z 200 μm na AISI 1040
podlago kovanega jekla z metodo napr{evanja s plazmo. Ni-Cr smo uporabili kot vmesni vezni premaz z debelino 20 μm nad
podlago za izbolj{anje oprijemljivosti prevleke. Pin-on-disk aparat je bila uporabljen za preskus suhe obrabe, v skladu s
standardi G99 Ameri{kega zdru`enja za testiranje in materiale, s konstantno obremenitvijo 10 N, na razli~nih drsnih razdaljah
1000 m, 2000 m in 3000 m. Preiskava je pokazala, da so mikrostruktura, debelina prevleke, poroznost, povr{inska hrapavost in
trdota vplivali na stopnjo obrabe. Pred in po testih obrabe, so bile meritve vzorcev povr{inske hrapavosti izvedene z uporabo
Talysurf instrumenta. Izkazalo se je, da je najve~ja vrednost (20,89 μm), pridobljena s prevleko iz aluminijevega
oksida-titanovega dioksida. Prakti~ni rezultati ka`ejo, da ima s ~istim kromom prevle~en vzorec zelo dobro odpornost na obrabo
kot tisti s kerami~nimi oksidi. Ka`e, da povr{inska prevleka s ~istim kromom na zgornji gredi mlina v sladkorni industriji
pove~a odpornost proti obrabi.
Klju~ne besede: aluminij, titan, krom, atmoferski plazma sprej, spoj na disk, obraba, Talysurf profilometer
1 INTRODUCTION
In many sugar industries, the top mill roller shaft,
used to crush sugarcane, is made up of AISI 1040 forged
carbon steel as this medium carbon, tensile steel shows
good strength, toughness and wear resistance. The roller
shaft has to operate under critical working conditions
such as heavy load, high speed, temperature and chemi-
cal environment, while it crushes the raw sugar cane to
extract the sugar cane juice. Hence, surface hardening of
the shaft is a must to improve the wear resistance as they
suffer from various types of degradation. Generally, the
shaft diameter will decrease due to continuous rotation
with a speed of 4 min–1 and accumulation of various im-
purities such as bagasse, ferrous and non-ferrous metals
and also due to improper lubrications in between the
journal bearing and the shaft. Hence, the shaft surface at
the pinion end should be coated with ceramic materials
with a good wear-resistance property.
The coating layer is very important because it
enhances the wear resistance of the metal substrate of
AISI 1040 forged steel to increase its life and efficiency.
Some of the most commonly used ceramic materials in
industrial applications are alumina (Al2O3), titania
(TiO2), Chromia (Cr2O3). S.-H. Yao1 studied nanostruc-
tured Al2O3 with 13 % of mass fractions of TiO2 coatings
and found that they showed better performance in
hardness and wear. Y. Sert et al.2 studied the wear resis-
tance of the plasma sprayed alumina – titania, titania,
chromia and chromia – titania and found the effect of
TiO2 content on Al2O3–TiO2 and Cr2O3–TiO2 coatings on
Al-based substrate, and concluded that hardness, coating
density and wear resistance changed with the TiO2
content.
Materiali in tehnologije / Materials and technology 51 (2017) 6, 939–944 939
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967–2017) – 50 LET/50 YEARS
UDK 620.1:620.193.95:669.1.017:621.926 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 51(6)939(2017)
B. A. Khan et al.3 studied the microstructural, surface
roughness and tribological properties of a coated spe-
cimen with alumina, titania and alumina-titania coating
materials and the results showed that pure alumina has
better wear properties than other coating materials, and it
was observed that the thermal barrier coating decreases
the wear rate compared to the parent metal. M. H.
Korkut et al.4 studied the wear behaviour of the ceramic
surfaces over different test durations on AISI 1040 mild
steel and found that the pure chromium III oxide (Cr2O3)
has a higher wear resistance than pure Al2O3 and its
compositions with TiO2, they concluded that wear
resistance decreased with an increase in the percentage
of TiO2 powder in Al2O3 mixture.
S. Islak et al.5 investigated the effect of TiO2 rate in
an Al2O3–TiO2 composite coating on SAE 1040 steel and
observed that the phase transformations take place from
stable -Al2O3 and anatase TiO2 to metastable -Al2O3,
rutile TiO2 and Al2TiO5 phase and as a result the micro-
hardness value was found to be 3 to 4.5 times higher than
that of SAE 1040 steel substrate materials due to a de-
crease in pore content when the TiO2 powder rate in-
creased in the composition. S. Salman et al.6 investigated
the thermal shock resistance of various ceramic oxides
coated on a cast iron substrate and found that zirconia
coated samples deformed at 1040 °C after 37 s when
compared to Cr2O3 which deformed at 960 °C after 33 s.
It was concluded that the Al2O3 coated specimen has less
thermal shock resistance since it deformed at 920 °C in
31 s.
M. S. Kumar et al.7 analyzed the tribological proper-
ties of thermally sprayed WC – 12 % of mass fractions
of Co and Al2O3 – 13 % of mass fractions of TiO2 on
AISI 1040 steel used in the automobiles and found that
the wear failure mechanism gets influenced more at
higher temperatures around 600 °C. It was also observed
that a carbide coating exhibited denser microstructured
and higher hardness than ceramic oxide coatings.
G. Bolleli et al.8 investigated the wear behaviour of
plasma-sprayed ceramic coatings (Al2O3, Al2O3 – 13 %
of mass fractions of TiO2 and Cr2O3) and found that the
Cr2O3 coating was the hardest and most anisotropic
among the other plasma-sprayed ceramics due to the low
interlamellar cohesion, whereas the Al2O3 – 13 % of
mass fractions of TiO2 was less hard and tough due to the
formation of a glassy phase and turns out to be quite
brittle.
A. Prasad et al.9 investigated the hardness of a
Ni/La2O3 composite powder that was cladded over AISI
1040 steel through microwave irradiation to improve the
wear resistance and observed the averaged Vickers
microhardness was about 319HV. It was further stated
that the hardness value depends upon the particle size,
microwave power and microwave exposure time. M. S.
Gök10 studied the microstructure and abrasive wear per-
formance of an AISI 1040 steel surface coated with
different ceramic materials and observed that a higher
rate of Cr2O3 in the composition produced a better and
higher microhardness value than other ceramic coating
materials. They also showed that increasing the propor-
tion of TiO2 in the composition affects the microhardness
value of the specimen.
P. Gadhari et al.11 studied the wear behaviour of a
N-P-Al2O3 composite coating on AISI 1040 steel and
showed that a change in the parameters like higher
annealing temperature 500 °C and reducing agent con-
centration (25 g/L) improved the wear resistance of the
coating. The amount of alumina content affects the wear
resistance property of the composite coating. M. Yunus
et al.12 investigated the wear behaviour of ceramic coat-
ings on a mild-steel substrate which has vast applications
in aerospace, gas turbine engines and power generators.
The result showed that the partially stabilized zirconia
(PSZ) has more thermal barrier and thermal cycling
resistance than alumina-titania and alumina. The coating
temperature (1000 °C), types of coating and thickness of
coating affect or influence the thermal barrier against the
ceramic coating materials.
2 EXPERIMENTAL PART
2.1 Substrate preparation
AISI 1040 forged steel was used as a substrate
material provided by M/s.Coimbatore Metal Mart. The
substrate AISI 1040 forged steel was made into circular
pins of 8 mm diameter and 30 mm length by performing
turning and facing operations in the lathe machine from
its original dimension of 30 mm diameter and 40 mm
length. Three types of coating materials were used:
ceramic oxide powders (99 % of mass fractions) Al2O3
as fused, primarily -phase with particle -325 mesh size,
(99 % of mass fractions) TiO2 traces metal basis with
particle – 325 mesh size, (98 % of mass fractions) Cr2O3
with particle size 5 μm provided by Sigma Aldrich Che-
micals Pvt Ltd, Bangalore, India. The mixtures formed
with six different compositions are shown in Table 1.
D. R. PONNUSAMY RAJARATHNAM, M. JAYARAMAN: INVESTIGATION OF THE WEAR BEHAVIOUR OF AN AISI 1040 ...
940 Materiali in tehnologije / Materials and technology 51 (2017) 6, 939–944
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967–2017) – 50 LET/50 YEARS
Figure 1: Schematic picture of plasma spray coating
Table 1: Chemical compositions (w/%) of ceramics for surface coat-
ing
Specimen No. Al2O3 TiO2 Cr2O3
S1 99 - -
S2 - 99 -
S3 - - 99
S4 45 55 -
S5 55 - 45
S6 - 45 55
Before spraying, the substrate was cleaned with ace-
tone. In the present work NiCr bond coat of 20 μm thick-
ness was deposited on the substrate surface materials so
as to compose an intermediate surface for the purpose of
best adhesion property and the coating thickness with
200 μm was deposited by plasma spraying process as
shown in Figure 1.
2.2 Thermal spraying equipment
Sulzer Metco 3 MB spraying guns were used for the
deposition of ceramic oxide layers provided by M/s.
SprayMet Technologies Pvt Ltd, Bangalore, India. The
parameters used for the deposition of ceramic oxide
coatings by thermal spraying process are shown in the
Table 2.
Table 2: Guidelines of plasma spray process
Gun METCO 3MB
Nozzle GH
Arc flow rate 80–90 L/min
Arc pressure 100–120 psi
Auxiliary gas flow rate 20–35 L/min
Auxiliary gas pressure 100 psi
Spray rate 2.0–6.5 kg/h
Arc voltage 60–70V
Arc current 490–590A
Spray distance 3–5 inches
Powder feed 40–50 grams/min
2.3 Characterization of coatings
The microstructures of the specimens coated with
Al2O3, TiO2, Cr2O3 and other compositions were charac-
terized under a Scanning Electron Microscope (SEM) to
study the microstructure of the substrate.
2.4 Microhardness of the ceramic oxide coatings
Hardness measurements were carried out to find the
microhardness value of the AISI 1040 steel substrate and
coated samples. The hardness test was carried out on the
top surface of the coatings with a load of 250 g and
dwell time period of 10 s and the average of three read-
ings are shown in the Table 3.
Table 3: Hardness value of the specimen
Specimens Vickers hardness number(HV)
AISI 1040 230
Al2O3 776
TiO2 340
Cr2O3 960
45 % Al2O3 + 55 % TiO2 448
55 % Al2O3 + 45 % Cr2O3 560
45 % TiO2 + 55 % Cr2O3 652
2.5 Surface roughness measurements
Talysurf instrument schematic sketch shown in Fig-
ure 2 was used to measure the surface roughness of the
specimens before and after wear tests. The cut-off length
was chosen as 0.8 mm for the instrument and a mean
value of five readings was calculated.
2.6 Wear test and evaluation
Ceramic oxide coated specimens were subjected to
dry wear tests by using a pin-on-disc wear testing device
as per ASTM G99-04 standards. The 8 mm diameter and
30 mm length cylindrical pin samples coated with alu-
mina, titania, chromia and combination of 45 % Al2O3 +
55 % TiO2, 55 % Al2O3 + 45 % Cr2O3, and 45 % TiO2 +
D. R. PONNUSAMY RAJARATHNAM, M. JAYARAMAN: INVESTIGATION OF THE WEAR BEHAVIOUR OF AN AISI 1040 ...
Materiali in tehnologije / Materials and technology 51 (2017) 6, 939–944 941
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967–2017) – 50 LET/50 YEARS
Figure 2: Schematic diagram of Talysurf instrument Figure 3: Pin-on-disc geometry
B. A. Khan et al.3 studied the microstructural, surface
roughness and tribological properties of a coated spe-
cimen with alumina, titania and alumina-titania coating
materials and the results showed that pure alumina has
better wear properties than other coating materials, and it
was observed that the thermal barrier coating decreases
the wear rate compared to the parent metal. M. H.
Korkut et al.4 studied the wear behaviour of the ceramic
surfaces over different test durations on AISI 1040 mild
steel and found that the pure chromium III oxide (Cr2O3)
has a higher wear resistance than pure Al2O3 and its
compositions with TiO2, they concluded that wear
resistance decreased with an increase in the percentage
of TiO2 powder in Al2O3 mixture.
S. Islak et al.5 investigated the effect of TiO2 rate in
an Al2O3–TiO2 composite coating on SAE 1040 steel and
observed that the phase transformations take place from
stable -Al2O3 and anatase TiO2 to metastable -Al2O3,
rutile TiO2 and Al2TiO5 phase and as a result the micro-
hardness value was found to be 3 to 4.5 times higher than
that of SAE 1040 steel substrate materials due to a de-
crease in pore content when the TiO2 powder rate in-
creased in the composition. S. Salman et al.6 investigated
the thermal shock resistance of various ceramic oxides
coated on a cast iron substrate and found that zirconia
coated samples deformed at 1040 °C after 37 s when
compared to Cr2O3 which deformed at 960 °C after 33 s.
It was concluded that the Al2O3 coated specimen has less
thermal shock resistance since it deformed at 920 °C in
31 s.
M. S. Kumar et al.7 analyzed the tribological proper-
ties of thermally sprayed WC – 12 % of mass fractions
of Co and Al2O3 – 13 % of mass fractions of TiO2 on
AISI 1040 steel used in the automobiles and found that
the wear failure mechanism gets influenced more at
higher temperatures around 600 °C. It was also observed
that a carbide coating exhibited denser microstructured
and higher hardness than ceramic oxide coatings.
G. Bolleli et al.8 investigated the wear behaviour of
plasma-sprayed ceramic coatings (Al2O3, Al2O3 – 13 %
of mass fractions of TiO2 and Cr2O3) and found that the
Cr2O3 coating was the hardest and most anisotropic
among the other plasma-sprayed ceramics due to the low
interlamellar cohesion, whereas the Al2O3 – 13 % of
mass fractions of TiO2 was less hard and tough due to the
formation of a glassy phase and turns out to be quite
brittle.
A. Prasad et al.9 investigated the hardness of a
Ni/La2O3 composite powder that was cladded over AISI
1040 steel through microwave irradiation to improve the
wear resistance and observed the averaged Vickers
microhardness was about 319HV. It was further stated
that the hardness value depends upon the particle size,
microwave power and microwave exposure time. M. S.
Gök10 studied the microstructure and abrasive wear per-
formance of an AISI 1040 steel surface coated with
different ceramic materials and observed that a higher
rate of Cr2O3 in the composition produced a better and
higher microhardness value than other ceramic coating
materials. They also showed that increasing the propor-
tion of TiO2 in the composition affects the microhardness
value of the specimen.
P. Gadhari et al.11 studied the wear behaviour of a
N-P-Al2O3 composite coating on AISI 1040 steel and
showed that a change in the parameters like higher
annealing temperature 500 °C and reducing agent con-
centration (25 g/L) improved the wear resistance of the
coating. The amount of alumina content affects the wear
resistance property of the composite coating. M. Yunus
et al.12 investigated the wear behaviour of ceramic coat-
ings on a mild-steel substrate which has vast applications
in aerospace, gas turbine engines and power generators.
The result showed that the partially stabilized zirconia
(PSZ) has more thermal barrier and thermal cycling
resistance than alumina-titania and alumina. The coating
temperature (1000 °C), types of coating and thickness of
coating affect or influence the thermal barrier against the
ceramic coating materials.
2 EXPERIMENTAL PART
2.1 Substrate preparation
AISI 1040 forged steel was used as a substrate
material provided by M/s.Coimbatore Metal Mart. The
substrate AISI 1040 forged steel was made into circular
pins of 8 mm diameter and 30 mm length by performing
turning and facing operations in the lathe machine from
its original dimension of 30 mm diameter and 40 mm
length. Three types of coating materials were used:
ceramic oxide powders (99 % of mass fractions) Al2O3
as fused, primarily -phase with particle -325 mesh size,
(99 % of mass fractions) TiO2 traces metal basis with
particle – 325 mesh size, (98 % of mass fractions) Cr2O3
with particle size 5 μm provided by Sigma Aldrich Che-
micals Pvt Ltd, Bangalore, India. The mixtures formed
with six different compositions are shown in Table 1.
D. R. PONNUSAMY RAJARATHNAM, M. JAYARAMAN: INVESTIGATION OF THE WEAR BEHAVIOUR OF AN AISI 1040 ...
940 Materiali in tehnologije / Materials and technology 51 (2017) 6, 939–944
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967–2017) – 50 LET/50 YEARS
Figure 1: Schematic picture of plasma spray coating
Table 1: Chemical compositions (w/%) of ceramics for surface coat-
ing
Specimen No. Al2O3 TiO2 Cr2O3
S1 99 - -
S2 - 99 -
S3 - - 99
S4 45 55 -
S5 55 - 45
S6 - 45 55
Before spraying, the substrate was cleaned with ace-
tone. In the present work NiCr bond coat of 20 μm thick-
ness was deposited on the substrate surface materials so
as to compose an intermediate surface for the purpose of
best adhesion property and the coating thickness with
200 μm was deposited by plasma spraying process as
shown in Figure 1.
2.2 Thermal spraying equipment
Sulzer Metco 3 MB spraying guns were used for the
deposition of ceramic oxide layers provided by M/s.
SprayMet Technologies Pvt Ltd, Bangalore, India. The
parameters used for the deposition of ceramic oxide
coatings by thermal spraying process are shown in the
Table 2.
Table 2: Guidelines of plasma spray process
Gun METCO 3MB
Nozzle GH
Arc flow rate 80–90 L/min
Arc pressure 100–120 psi
Auxiliary gas flow rate 20–35 L/min
Auxiliary gas pressure 100 psi
Spray rate 2.0–6.5 kg/h
Arc voltage 60–70V
Arc current 490–590A
Spray distance 3–5 inches
Powder feed 40–50 grams/min
2.3 Characterization of coatings
The microstructures of the specimens coated with
Al2O3, TiO2, Cr2O3 and other compositions were charac-
terized under a Scanning Electron Microscope (SEM) to
study the microstructure of the substrate.
2.4 Microhardness of the ceramic oxide coatings
Hardness measurements were carried out to find the
microhardness value of the AISI 1040 steel substrate and
coated samples. The hardness test was carried out on the
top surface of the coatings with a load of 250 g and
dwell time period of 10 s and the average of three read-
ings are shown in the Table 3.
Table 3: Hardness value of the specimen
Specimens Vickers hardness number(HV)
AISI 1040 230
Al2O3 776
TiO2 340
Cr2O3 960
45 % Al2O3 + 55 % TiO2 448
55 % Al2O3 + 45 % Cr2O3 560
45 % TiO2 + 55 % Cr2O3 652
2.5 Surface roughness measurements
Talysurf instrument schematic sketch shown in Fig-
ure 2 was used to measure the surface roughness of the
specimens before and after wear tests. The cut-off length
was chosen as 0.8 mm for the instrument and a mean
value of five readings was calculated.
2.6 Wear test and evaluation
Ceramic oxide coated specimens were subjected to
dry wear tests by using a pin-on-disc wear testing device
as per ASTM G99-04 standards. The 8 mm diameter and
30 mm length cylindrical pin samples coated with alu-
mina, titania, chromia and combination of 45 % Al2O3 +
55 % TiO2, 55 % Al2O3 + 45 % Cr2O3, and 45 % TiO2 +
D. R. PONNUSAMY RAJARATHNAM, M. JAYARAMAN: INVESTIGATION OF THE WEAR BEHAVIOUR OF AN AISI 1040 ...
Materiali in tehnologije / Materials and technology 51 (2017) 6, 939–944 941
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967–2017) – 50 LET/50 YEARS
Figure 2: Schematic diagram of Talysurf instrument Figure 3: Pin-on-disc geometry
55 % Cr2O3 oxides of coating thickness 200 μm were
used as test materials. Counter face material made from
hardened steel was used as a disc. For each sample dry-
sliding wear tests were carried out three times against a
constant load of 10 N for a sliding speed of 260 min–1,
525 min–1 and 790 min–1 under a sliding distance of
1000 m, 2000 m and 3000 m respectively. The corres-
ponding weight losses of the coated specimens were
calculated by means of an electronic weighing balance.
The microstructural characteristics and wear behaviour
were identified by means of the wear scars observed by
using SEM for both the coated and uncoated specimens.
The pin-on-disc geometry was shown in Figure 3.
3 EXPERIMENTAL RESULTS AND DISCUSSION
3.1 Microstructure of ceramic oxide coating
Scanning Electron Microscope (SEM) images of the
AISI 1040 forged steel substrate and ceramic oxide
powder samples at 200× magnification are shown in
Figure 4. Figure 4a shows various elements present in
AISI 1040 forged steel substrate and the increase of the
ferrite grain size at the inner regions and ferrite, for
example, similar to white regions and perlite, for exam-
ple, similar to dark side regions were found. Figures 4b
to 4d represent the morphological structure of the Al2O3,
TiO2 and Cr2O3 particles. The Al2O3 and TiO2 powders
have distinctive grain sizes, exhibited an irregular mor-
phology and were sharp edged because of the agglo-
meration of essential particles.The alumina particles are
generally nano-sized and the shape of particle is non-
spherical. Particle density or true density gives data
about the sort of material present in the sample. A
particle density higher than 1.0 g/cc is attributed to a
high alumina content in the sample rather than the orga-
nic matter. The porosity is likewise sensibly high as
expected.13 It demonstrates that the chromium oxide is in
pure form and the particles are white colored nano-
particles that are almost rhombohedral and isolated.
Photographic images of the ceramic oxide coated
specimens on AISI 1040 forged steel substrate are shown
in Figure 5. Figure 5a to 5f show that the Al2O3, TiO2,
Cr2O3, 45 % Al2O3 + 55 % TiO2, 55 % Al2O3 + 45 %
Cr2O3 and 45 % TiO2 + 55 % Cr2O3 particles are
homogenously distributed with less porosity present on
the surface of the specimens. An examination of these
images revealed that the substrate surface layer and the
ceramic coating layer were homogenously fused and
there were no pores, cracks, and spaces on the coating
area.
3.2 Surface-roughness measurement
The surface roughness (Ra) values were higher for
both the coated and uncoated samples before the wear
test, whereas the Ra values were lower for both the
coated and uncoated samples after the wear test. The re-
corded values are shown in Figure 6. The specimen
coated with 55 % Al2O3 + 45 % Cr2O3 and having a
coating thickness of 200 μm is shows a smaller Ra value
before the wear test when compared to other values of
coated and uncoated specimens.The specimen coated
with (99 % of mass fractions) TiO2 and having a coating
thickness of 200 μm shows a lower Ra value after the
wear test when compared to the other values of the
coated and uncoated specimens after the wear test.
D. R. PONNUSAMY RAJARATHNAM, M. JAYARAMAN: INVESTIGATION OF THE WEAR BEHAVIOUR OF AN AISI 1040 ...
942 Materiali in tehnologije / Materials and technology 51 (2017) 6, 939–944
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Figure 6: Surface roughness of coated and uncoated specimens
Figure 4: SEM images of steel substrate and ceramic oxides at 200×
magnification: a) AISI 1040 forged steel, b) Al2O3, c) TiO2, d) Cr2O3
Figure 5: Photographic image of a) Al2O3, b)TiO2, c) Cr2O3 d) 45 %
Al2O3 + 55 % TiO2, e) 55 % Al2O3 + 45 % Cr2O3 and f) 45 % TiO2 +
55% Cr2O3
3.3 Microhardness values of ceramic oxide coating
Figure 7 shows the recorded microhardness values
for different ceramic oxide coated and bare specimens.
From the recorded values, the 99 % Cr2O3 coated
specimen has the highest microhardness value when
compared to the other coated and uncoated specimens.
3.4 Wear-rate performance of ceramic oxide coated
specimens
By using a pin-on-disc apparatus, dry-sliding wear
tests were carried out on the ceramic oxide coated and
uncoated AISI 1040 specimens according to the ASTM
G99-04 standard wear test. The effect of sliding distance
in the wear loss of the uncoated and coated specimens at
a constant load of 10 N for the different composition
coating powder is shown in Figure 8.
The specimen coated with 99 % Cr2O3 and having a
thickness 200 μm has comparatively less wear loss for all
the sliding distances rather than the uncoated AISI 1040
forged steel specimen and other combinations of cera-
mic-oxide-coated specimens. The specimen coated with
Al2O3-55 % TiO2 shows a higher wear loss at all the
sliding distances when compared to all the other coated
specimens. SEM images of ceramic oxide coated speci-
mens and AISI 1040 forged steel after wear test under a
constant load of 10 N are shown in Figures 9. From
Figure 9a to 9f it was observed that the Al2O3-55 % TiO2
coated specimen experienced serious wear condition
described by shearing and plastic distortion and the
surface of the substrate has turned out to be rough and
D. R. PONNUSAMY RAJARATHNAM, M. JAYARAMAN: INVESTIGATION OF THE WEAR BEHAVIOUR OF AN AISI 1040 ...
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Figure 8: Effect of sliding distance on the wear loss for 200 μm
Figure 9: SEM microstructure after wear test of: a) Al2O3, b) TiO2, c) Cr2O3, d) 45 Al2O3+55 TiO2, e) 55 Al2O3 + 45 Cr2O3, f) 45 TiO2 + 55
Cr2O3, g) AISI 1040 forged steel
Figure 7: Microhardness of coated specimens and bare AISI 1040
forged steel
55 % Cr2O3 oxides of coating thickness 200 μm were
used as test materials. Counter face material made from
hardened steel was used as a disc. For each sample dry-
sliding wear tests were carried out three times against a
constant load of 10 N for a sliding speed of 260 min–1,
525 min–1 and 790 min–1 under a sliding distance of
1000 m, 2000 m and 3000 m respectively. The corres-
ponding weight losses of the coated specimens were
calculated by means of an electronic weighing balance.
The microstructural characteristics and wear behaviour
were identified by means of the wear scars observed by
using SEM for both the coated and uncoated specimens.
The pin-on-disc geometry was shown in Figure 3.
3 EXPERIMENTAL RESULTS AND DISCUSSION
3.1 Microstructure of ceramic oxide coating
Scanning Electron Microscope (SEM) images of the
AISI 1040 forged steel substrate and ceramic oxide
powder samples at 200× magnification are shown in
Figure 4. Figure 4a shows various elements present in
AISI 1040 forged steel substrate and the increase of the
ferrite grain size at the inner regions and ferrite, for
example, similar to white regions and perlite, for exam-
ple, similar to dark side regions were found. Figures 4b
to 4d represent the morphological structure of the Al2O3,
TiO2 and Cr2O3 particles. The Al2O3 and TiO2 powders
have distinctive grain sizes, exhibited an irregular mor-
phology and were sharp edged because of the agglo-
meration of essential particles.The alumina particles are
generally nano-sized and the shape of particle is non-
spherical. Particle density or true density gives data
about the sort of material present in the sample. A
particle density higher than 1.0 g/cc is attributed to a
high alumina content in the sample rather than the orga-
nic matter. The porosity is likewise sensibly high as
expected.13 It demonstrates that the chromium oxide is in
pure form and the particles are white colored nano-
particles that are almost rhombohedral and isolated.
Photographic images of the ceramic oxide coated
specimens on AISI 1040 forged steel substrate are shown
in Figure 5. Figure 5a to 5f show that the Al2O3, TiO2,
Cr2O3, 45 % Al2O3 + 55 % TiO2, 55 % Al2O3 + 45 %
Cr2O3 and 45 % TiO2 + 55 % Cr2O3 particles are
homogenously distributed with less porosity present on
the surface of the specimens. An examination of these
images revealed that the substrate surface layer and the
ceramic coating layer were homogenously fused and
there were no pores, cracks, and spaces on the coating
area.
3.2 Surface-roughness measurement
The surface roughness (Ra) values were higher for
both the coated and uncoated samples before the wear
test, whereas the Ra values were lower for both the
coated and uncoated samples after the wear test. The re-
corded values are shown in Figure 6. The specimen
coated with 55 % Al2O3 + 45 % Cr2O3 and having a
coating thickness of 200 μm is shows a smaller Ra value
before the wear test when compared to other values of
coated and uncoated specimens.The specimen coated
with (99 % of mass fractions) TiO2 and having a coating
thickness of 200 μm shows a lower Ra value after the
wear test when compared to the other values of the
coated and uncoated specimens after the wear test.
D. R. PONNUSAMY RAJARATHNAM, M. JAYARAMAN: INVESTIGATION OF THE WEAR BEHAVIOUR OF AN AISI 1040 ...
942 Materiali in tehnologije / Materials and technology 51 (2017) 6, 939–944
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Figure 6: Surface roughness of coated and uncoated specimens
Figure 4: SEM images of steel substrate and ceramic oxides at 200×
magnification: a) AISI 1040 forged steel, b) Al2O3, c) TiO2, d) Cr2O3
Figure 5: Photographic image of a) Al2O3, b)TiO2, c) Cr2O3 d) 45 %
Al2O3 + 55 % TiO2, e) 55 % Al2O3 + 45 % Cr2O3 and f) 45 % TiO2 +
55% Cr2O3
3.3 Microhardness values of ceramic oxide coating
Figure 7 shows the recorded microhardness values
for different ceramic oxide coated and bare specimens.
From the recorded values, the 99 % Cr2O3 coated
specimen has the highest microhardness value when
compared to the other coated and uncoated specimens.
3.4 Wear-rate performance of ceramic oxide coated
specimens
By using a pin-on-disc apparatus, dry-sliding wear
tests were carried out on the ceramic oxide coated and
uncoated AISI 1040 specimens according to the ASTM
G99-04 standard wear test. The effect of sliding distance
in the wear loss of the uncoated and coated specimens at
a constant load of 10 N for the different composition
coating powder is shown in Figure 8.
The specimen coated with 99 % Cr2O3 and having a
thickness 200 μm has comparatively less wear loss for all
the sliding distances rather than the uncoated AISI 1040
forged steel specimen and other combinations of cera-
mic-oxide-coated specimens. The specimen coated with
Al2O3-55 % TiO2 shows a higher wear loss at all the
sliding distances when compared to all the other coated
specimens. SEM images of ceramic oxide coated speci-
mens and AISI 1040 forged steel after wear test under a
constant load of 10 N are shown in Figures 9. From
Figure 9a to 9f it was observed that the Al2O3-55 % TiO2
coated specimen experienced serious wear condition
described by shearing and plastic distortion and the
surface of the substrate has turned out to be rough and
D. R. PONNUSAMY RAJARATHNAM, M. JAYARAMAN: INVESTIGATION OF THE WEAR BEHAVIOUR OF AN AISI 1040 ...
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MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967–2017) – 50 LET/50 YEARS
Figure 8: Effect of sliding distance on the wear loss for 200 μm
Figure 9: SEM microstructure after wear test of: a) Al2O3, b) TiO2, c) Cr2O3, d) 45 Al2O3+55 TiO2, e) 55 Al2O3 + 45 Cr2O3, f) 45 TiO2 + 55
Cr2O3, g) AISI 1040 forged steel
Figure 7: Microhardness of coated specimens and bare AISI 1040
forged steel
debris formed because of the wear. The Al2O3-coated
specimen had a wear mechanism on the surface in the
form of flaky micro-cracks. This could be attributed to
the high hardness values of the specimens. Micro-cracks
occur if a critical value is exceeded in loading and
abrasive wear also takes place in relation to the fracture
toughness of the abraded material. The TiO2-coated
specimen showed that the wear mechanism on the
surface formed micro-cutting of various widths along
with plastic deformation because of micro crackings.
Figure 9g reveals that the transfer of the materials that
occurred from the pin to the disc. The debris produced
throughout the test was deposited on both sides of the
wear track. Over the wear track a few patches of the
initial surface are observed, indicating that the trans-
ferred steel film was detached as a result of a fatigue
process.
4 CONCLUSIONS
The AISI 1040 forged steel substrate was coated with
alumina, titania, chromia individually and again with
different combinations of ceramic oxides such as 45 %
Al2O3 + 55 % TiO2, 55 % Al2O3 + 45 % Cr2O3, and 45 %
TiO2 + 55 % Cr2O3 by using a plasma-spraying process
with an intermediate bond coat of NiCr, SEM tests were
carried out to determine the surface roughness and
adhesion of the coating onto the AISI 1040 substrate.
The specimen coated with 99 % Cr2O3 has higher
microhardness values among all the ceramic-oxide-
coated specimens, which was followed by 99 % Al2O3,
45 % TiO2 + 55 % Cr2O3, 55 % Al2O3 + 45 % Cr2O3. The
lowest hardness value was obtained from the ceramic
oxide coating surface with a mixture proportion of 45 %
Al2O3 + 55 % TiO2.
The chromia-coated specimen showed excellent wear
property when compared to other coating materials due
to its excellent adhesion to the base metal.
The increase in the weight percentage of TiO2 in the
Al2O3 ceramic material affects the microhardness value
of the specimens in a decreasing manner.
The microhardness values of the coated specimens
influence the wear loss. The specimens having higher
microhardness also have a higher wear resistance and
cause less wear loss.
If the weight percentage of TiO2 in Cr2O3 ceramic
materials increases, this decreases the microhardness
value of the specimens.
From the experimental results it can be concluded
that the pure 99 % Cr2O3 coated AISI 1040 forged steel
specimen showed better wear resistance property due to
dense, compact, defects free and good adhesion charac-
teristics, while compared to other coating materials.
Hence, it is recommended for surface coating on the top
mill roll shafts used in sugarcane industries to increase
the wear resistance of the shaft.
Acknowledgement
The research work was supported by my father Mr.
D. Ponnusamy and my spouse Mrs B. Malathi. Special
thanks to Professor Dr. K. K. Ramasamy and Dr. M.
Premkumar from Paavai Engineering College, Nama-
kkal, India, for their valuable help.
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Al2O3-TiO2-Cr2O3 coating, Mater. Technol., 47 (2013) 2, 181–183
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behaviour of a plasma – sprayed Al2O3-TiO2 coating on Al-6082T6
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Gok, Effect of the abrasive grit size on the wear behaviour of
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(2013) 6, 695–699
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Stokes, M. Saleem Hashmi, Effect on microstructure of TiO2 rate in
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6 S. Salman, R. Kose, L. Urtekin, F. Findik, An investigation of
different ceramic coating thermal properties, Mater. Des., 27 (2006)
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of thermally sprayed ceramic oxide coatings, Wear, 261 (2006),
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9 A. Prasad, D. Gupta, M. R. Sankar, A. N. Reddy, Experimental
investigations of Ni/La2O3 composite micro-cladding on AISI 1040
steel through microwave irradiation, 5th Int. & 26th All India
Manufacturing Techno., Des. and Res. Conference, 2014, 55–61
10 M. S. Gok, The effect of different ceramics on the abrasive wear
behavior of coating surface produced by the plasma process, Int. J. of
the Phy. Sci., 5 (2010) 5, 535–546
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Ni–P–Al2O3 composite coating by optimizing process parameters
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adsorption data, J. Am. Chem. Soc ., 70 (1948) 4,1405–1410
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944 Materiali in tehnologije / Materials and technology 51 (2017) 6, 939–944
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M. BOROUNI et al.: SYNTHESIS AND CHARACTERIZATION OF AN IN-SITU MAGNESIUM-BASED ...
945–951
SYNTHESIS AND CHARACTERIZATION OF AN IN-SITU
MAGNESIUM-BASED CAST NANO COMPOSITE VIA NANO-SiO2
ADDITIONS TO THE MELT
SINTEZA IN KARAKTERIZACIJA IN SITU NANOKOMPOZITA NA
OSNOVI MAGNEZIJA Z NANO-SiO2 DODATKOM ZA TALJENJE
Mansour Borouni1, Behzad Niroumand2, Ali Maleki3
1Isfahan University of Technology, Pardis College, Materials Engineering Group, Isfahan 84156-83111, Iran
2Isfahan University of Technology, Department of Mechanical Engineering, Isfahan, 84156-83111, Iran
3Isfahan University of Technology, Research Institute for Steel, Isfahan, 84156-83111, Iran
m.borouni@pa.iut.ac.ir
Prejem rokopisa – received: 2017-04-01; sprejem za objavo – accepted for publication: 2017-05-12
doi:10.17222/mit.2017.036
In this study, AZ91C magnesium matrix in-situ nano-composites reinforced with oxide particles were produced by the addition
of 2 % of mass fractions of silica nanoparticles to the melt using the stir-casting method. For this purpose, nano-silica powder
was mixed in molten AZ91C by a special procedure and stirred for 15 min at 750 °C and cast in a preheated die at 720 °C.
Control samples were also cast under the same conditions. Improved microstructure, reduced porosity and increased hardness,
tensile strength and yield strength of the composite sample were revealed by microstructural and mechanical investigations. The
hardness, yield strength and tensile strength values increased from 65 BHN, 82 MPa and 165 MPa for the monolithic samples to
77 BHN, 97 MPa and 175 MPa for the in-situ formed cast composites. Microstructural and EDS analyses suggested the in-situ
formation of Al2O3, MgAl2O4 and MgO oxide particles by in-situ reaction of the Al, Mg and SiO2 in the melt.
Keywords: AZ91C alloy, in-situ cast nano-composite, silica nanoparticles, mechanical properties
V {tudiji so bili izdelani AZ91C nanokompoziti in situ, na podlagi magnezijeve matrike in oja~ani z oksidnimi delci z dodatkom
2 % nanodelcev silicija za topljenje, z uporabo metode litja z me{anjem. Za ta namen je bil nanosilicijev prah zme{an v
raztopljen AZ91C s posebno metodo in nato 15 min me{an na 750 °C in lit v predogretem modelu na 720 °C. Preizku{anci so
bili ravnotako liti v enakih pogojih. Izbolj{ana mikrostruktura, zmanj{ana poroznost in pove~ana trdota, napetostna trdnost in
napetost vzorcev kompozita so bili odkriti s preiskavami mikrostrukture in z mehanskimi preiskavami. Vrednosti trdote,
napetosti te~enja in natezne napetosti so se pove~ali iz 65 BHN, 82 Mpa in 165 MPa in za monolitne vzorce na 77 BHN, 97
MPa in 175 MPa za in situ formirane lite kompozite. Mikrostrukture in EDS-analize so predlagale in situ formacijo Al2O3,
MgAl2O4 in MgO oksidne delce z in situ reakcijo Al, Mg in SiO2 v topljenem.
Klju~ne besede: AZ91C zlitina, in situ litje nanokompozitov, nanodelci silicija, mehanske lastnosti
1 INTRODUCTION
Besides extensive applications in automobile and
aerospace industries, magnesium and its alloys have had
considerable growth in three markets of communica-
tions, computer and video and photography cameras.
Magnesium is the lightest industrial metal with a density
of 1.74 g/cm3. Magnesium has a high specific strength
and therefore it is used extensively as the metal matrix in
the manufacturing of composites. Among the alloys of
magnesium, Mg-Al-Zn alloys, specifically the AZ91
alloy, have extensive applications in various industries.
Corrosion resistance and relatively high strength are the
particular properties of the AZ91 alloy compared to
other magnesium alloys. The AZ91 alloy is one of the
most common magnesium alloys to produce magne-
sium-matrix composites.1–5
For producing magnesium-matrix composites, rein-
forcing materials with different shapes, sizes and
materials are used. Micron-sized ceramic reinforcements
including carbides, borides and oxides are the most
common.2,5 Various studies are carried out in the field of
magnesium-matrix composites reinforced with ceramic
particles. For instance, in 2008, Hassan and Gupta pro-
duced a magnesium composite reinforced with Al2O3
particles with 0.3-micron sizes using disintegrated melt
deposition method and reported improved yield strength,
tensile strength and flexibility by 2 % of mass fractions
increase of Al2O3 particles.6
By changing the scale of the reinforcing particles
from micrometer to nanometer, their specific surface is
increased significantly and the impact of the properties
of the surface of the particles become more important.
Since one of the mechanisms to increase the properties
of the composites is the load transfer in the interface of
the matrix and reinforcement particles, using nano-
particles, the surface of the reinforcement which is in
contact with the matrix is increased and higher increases
in the properties are expected.7 In a research in 2012,
AZ91D-TiB2 nano-composites were manufactured using
ultrasonic mixing and their sub-structure and mechanical
properties were studied. For AZ91D nano-composites
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UDK 67.017:620.3:621.74:669.721 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 51(6)945(2017)