The document summarizes a national conference on materials, manufacturing, and quality control held on February 19-20, 2015. The conference provided an opportunity for researchers, academics, practitioners, and industry professionals to exchange ideas in these fields. Key lectures from eminent researchers explored novel research areas. Authors were invited to discuss challenges and solutions in materials, manufacturing, and quality control. Accepted papers from the reviewed submissions were presented. The proceedings were published with an ISBN number.

1. TEQIP-II Sponsored National Conference on “Latest Developments in Materials, Manufacturing and Quality
Control” on 19-20th
February, 2015 (ISBN 978-93-5196-055-3)
Department of Mechanical Engineering, Giani Zail Singh Punjab Technical University Campus, Bathinda Page i

2. TEQIP-II Sponsored National Conference on “Latest Developments in Materials, Manufacturing and Quality
Control” on 19-20th
February, 2015 (ISBN 978-93-5196-055-3)
Department of Mechanical Engineering, Giani Zail Singh Punjab Technical University Campus, Bathinda Page ii
ABOUT THE CONFERENCE
The department of Mechanical Engineering of GZS PTU is organizing 3rd
National Conference on
„Latest Developments in Materials, Manufacturing and Quality Control‟ from 19-20th
February,
2015. This conference shall be providing a great opportunity where the researchers, academicians,
practitioners and professional from industry meet to exchange their ideas and experiences on
related fields with each other.
Key note lectures and the invited talks by the eminent researchers are arranged in the conference
which will help the delegates from all across the country to explore novel areas of research.
Authors/researchers are invited to exchange ideas and to discuss the practical challenges
encountered and solution adopted in Materials, Manufacturing and Quality Control. The conference
covers the research areas under different themes related to the conference title. The papers received
in the conference will be reviewed by the technical review committee of the conference and the
authors of the accepted papers will be invited for presentation of the papers.
ISBN of Proceedings 978-93-5196-055-3

3. TEQIP-II Sponsored National Conference on “Latest Developments in Materials, Manufacturing and Quality
Control” on 19-20th
February, 2015 (ISBN 978-93-5196-055-3)
Department of Mechanical Engineering, Giani Zail Singh Punjab Technical University Campus, Bathinda Page 294
ROLE OF RARE EARTH ELEMENTS IN THERMAL SPRAY COATINGS
Harkulvinder Singh1
*, Sukhpal Singh Chatha2
, Buta Singh Sidhu3
1,2
Yadavindra College of Engineering, Punjabi University Guru Kashi Campus, Talwandi Sabo, Punjab, India-151302
3
Punjab Technical University, Jalandher, Punjab, India-151302
*Corresponding author email-id harkulvinder84@gmail.com
Abstract: Metals are unable to meet requirement for both
the high temperature strength and the high temperature
corrosion resistance, simultaneously, so protective
coatings are used to counter the latter. The primary aim
of the coating/surface treatment is the ability to
produce a stable,slow-growing surface protective oxide
providing a barrier between the coated alloy and the
environment. The oxidation resistance of alloy coatings
failures caused by the stresses generated in protective
oxide scales.Therefore, the processes of scale cracking
and spalling are the key factor to influence the lifetime
of coatings. In order to improve the adherence &
oxidation resistance of coating rare earth elements (La,
Zr, Ce, Y etc.) are added in the coating composition.It
is concluded that the scale nucleates at the reactive
element oxide particles on the surface; blocks short-
circuit diffusion paths by segregating reactive element
ions and reduces the stresses in oxide scale by altering
the microstructure.
1. INTRODUCTION
With the advancement in science and technology, the
expectations regard the life of the component in
working conditions also increased. Most of the
materials used in the modern industrial components
and systems often subjected to take failure at a
premature stage of their life, when component
subjected under high temperature environment (Singh
& Singh, 2014). Metals are unable to meet requirement
for both the high temperature strength and the high
temperature corrosion resistance, simultaneously, so
protective coatings are used to counter the latter (Sidhu
et al, 2006). Among the available alternatives for
metal surface protection in aggressive environments,
the thermal spray process has been widely researched
and used in recent years. (Brandolt et al, 2014). The
primary aim of the coating/surface treatment is the
ability to produce a stable,slow-growing surface
protective oxide providing a barrier between the
coated alloy and the environment (Chavla et al,
2013). The oxidation resistance of alloy coatings
failures caused by the stresses generated in protective
oxide scales. The stresses mainly consist of growth
and thermal stresses, due to which oxide scale
cracking and spallation take place. Therefore, the
processes of scale cracking and spalling are the key
factor to influence the lifetime of coatings (Yedong
et al, 2013).
The addition of rare-earth (RE) compounds in metals
realizes multiple functions, such as purification,
modification and alloying, and thus can improve a
range of properties of metals to various extents
(Zhang et al, 2008).
In order to improve the adherence & oxidation
resistance of coating rare earth elements (La, Zr, Ce,
Y etc.) are added in the coating composition.Reactive
element act as vacancy sinks to suppress void
formation at the interface of alloy & scale, formation
of oxide pegs at alloy-scale interface, segregation of
reactive element to the alloy-oxide interface to form
a graded seal which strengthens the alloy-scale bond
(kumar et al, 2014). It is concluded that the scale
nucleates at the reactive element oxide particles on the
surface; blocks short-circuit diffusion paths by
segregating reactive element ions and reduces the
stresses in oxide scale by altering the microstructure
(Seal et al, 2007). In this paper, beneficial effects of
rare earth elements discussed in order to better
understand the role of RE in the corrosion process.
2. RARE EARTH COATINGS
Ma et al, 1994 studied the effect of rare earth (RE)
oxides (Y2O3, Gd2O3) on hot corrosion of NiAl
coating deposited on M38G alloy material exposed to
Na2SO4+25wt.%K2SO4 fused salt at 850ºC. It was
found that the RE oxide addition in coating improves
the corrosion resistance and also lighten corrosion
degree of sulfides on the coating through the
formation of stable RE-oxygen sulfides. In another
study Bottino et al, 1995 examined that the oxidation
behaviour of CeO2 coating on AISI 347 grade stainless
steel subjected to non-isothermal and isothermal
oxidation tests at 1273K in dry air in a vertically placed
quartz tube reactor.SEM, EDS, EPMA and XRD results
shows CeO2 significantly improves the oxidation rate
by outward migration of cations to the ingress of
oxidant species and scale adherence to the alloy
substrate due to change grain size of the oxide scale by
pegging mechanism. Bonnet et al, 1996 used CVD
technique to deposit thin oxide films of Cr2O3, Al2O3,

4. TEQIP-II Sponsored National Conference on “Latest Developments in Materials, Manufacturing and Quality
Control” on 19-20th
February, 2015 (ISBN 978-93-5196-055-3)
Department of Mechanical Engineering, Giani Zail Singh Punjab Technical University Campus, Bathinda Page 295
Cr2O3+Nd2O3, Al2O3+ Nd2O3 and Sm2O3+A12O3-
elements on F17Ti steel substrate and exposed tohigh-
temperature oxidation in air at 1273 K for 40 cycles.In
cyclic thermal conditions, the Al2O3 coating appeared to
be better than the Cr2O3 coating. Moreover, it was
confirmed that the presence of a rare earth oxide has a
positive effect on the alloy corrosion resistance, even if
it is not large. Seal et al, 1998 investigated that the low
and high Cr steel samples coated with cerium oxide by
dipped into slurry of CeO2 powder dispersed in ethyl
alcohol and exposed to high temperature oxidation in
dry air at 923 K for 24 h. Outcome results showed that
the presence of Ce on the surface facilitates the
formation of an early Cr2O3 protective layer. Thus, the
ion migration has shifted from outward cation migration
to inward anion ingress and Ce allows transition metal
oxides to be more covalent bond, which improves the
oxide layer‘s ability for slower oxygen uptake to
provide a more protective barrier. In another study
Nacan et al, 2003 observed that TiN coatings with
addition of rare earth element (0.4wt% Ce) deposited
on W18Cr4V high speed steel by means of vacuum
arc ion plating and exposed to Nacl solution at
600ºC. The results reveal that the microhardness of
the coating decreases slightly with the addition of
cerium. Cerium is beneficial to improving oxidation
resistance of the coating, therefore the oxygen atoms
cannot easily pass through the crystal defects or pore
space to contact the substrate.This may prevent the
forming of inner oxidized zone on the substrate
surface.
FeAl based coatings containing various amounts of
CeO2 (2 to 8 wt.%) were deposited onto carbon steel
by HVOF spraying, and exposed to H2S–H2–O2–Ar
environment at 700°C for 300 h.SEM, EDS and XRD
techniques result showed that the sulfidation
resistance of FeAl coating is improved by an addition
of 2–5 wt.% CeO2, which inhibits the outward
diffusion of Fe, acts as traps for sulphur in the splat
boundaries, and slows down the depletion of Al in
the coating (Chen & Xiao et al, 2006).Huiming et al,
2007 evaluated that the isothermal and cyclic
oxidation behaviors of chromium substrate with and
without nanometric CeO2 coating at and subjected to
cyclic oxidation at 900ºC in air. SEM, TEM and
HREM results found that improvement in oxidation
resistance of chromium is believed mainly due to that
ceria coating. CeO2 coating greatly reduced the
growth speed and grain size of Cr2O3. This fine
grained Cr2O3 oxide film might have better high
temperature plasticity. Meanwhile, ceria application
reduced the size and number of interfacial defects
and enhanced the adhesive property of Cr2O3 oxide
scale formed on Cr substrate.
Hot corrosion behaviour of Superfer 800H, Superco
605 and Superni 75 has been investigated after TSC
of Y2O3 in a Na2SO4–60%V2O5 environment at
900°C for 50 cycles. The results revealed that the
Y2O3 coating provide better adhesion of the scale in
all the alloys due to dispersed oxide phases that act
as heterogeneous nucleation sites for oxide grains
thereby reducing the inter-nuclear distance, which
allows more rapid formation of a continuous chromia
film and produces a linear oxide grain size (Singh et
al, 2009). In another work Kamal et al, 2010
investigated that hot corrosion resistance of
detonation-gun-sprayed NiCrAlY + 0.4 wt.% CeO2
coatings on superalloys, namely, superni 75, superni
718, and superfer 800H in molten 40% Na2SO4-60%
V2O5 salt environment at 900ºC for 100
cycles.Coated superfer 800H alloy showed the
highest corrosion resistance among the examined
superalloys.Better performance of coated superfer
800H might be due to uniform, dense, thick scale
formed on the surface mainly consisting oxides of
Cr, Ni, Al, and the spinels of NiCr2O4 and NiAl2O4.
Presence of CeO2 with vanadium across the coating
depicts the formation of CeVO4, which might have
further contributed in reducing hot corrosion attack
as shown in fig.1.
Fig.1. Schematic diagram showing proposed hot corrosion
mechanism of the NiCrAlY + 0.4 wt.% CeO2 coated
superfer 800H at 900ºC in Na2SO4 + 60% V2O5 after 100
cycles (Kamal et al, 2010).
Yttrium was found to be segregated along the grain
boundaries of A12O3 and lowers the scale growth
rates. RE segregate to oxide grain boundaries, where
they can significantly reduce the outward transport of
Al, hence decrease the rate of oxidation and
contributed to the improved scale adherence and
reduced interfacial void formation.

5. TEQIP-II Sponsored National Conference on “Latest Developments in Materials, Manufacturing and Quality
Control” on 19-20th
February, 2015 (ISBN 978-93-5196-055-3)
Department of Mechanical Engineering, Giani Zail Singh Punjab Technical University Campus, Bathinda Page 296
Mahesh et al, 2010 observed that the high temperature
oxidation behaviour of HVOF sprayed ceria (0.4 wt.%)
added NiCrAlY coatings has been studied for bare and
coated Superni 76, Superni 750 and Superfer 800
superalloys in air at 900◦C.The NiCrAlY–0.4 wt. %
CeO2 coated specimen showed negligible microspalling
of the scale. During the initial period of exposure,
oxygen penetrates into the coating through the open
pores and splat boundaries. As the oxidation process
continues, the top surface of the oxidized scale consists
of oxides of nickel, chromium, aluminum and spinel of
nickel and chromium. Oxides of aluminum and
chromium prevent the permeation of the oxidising
species into the coating and substrate superalloy.
Streaks of cerium oxide are found along the splat
boundaries, which assist in enhancing the oxidation
resistance of coatings. Cu-14Al-4.5Fe bronze coating
with and without addition of 0.6wt % Ce were
deposited with the help of atmospheric plasma spraying
on medium-carbon 45# steel substrate.The effects of Ce
on the coating interface bonding strength, coatings and
bonding interface microstructure were investigated by
tensile machine, XRD, SEM and EPMA analysis. The
results showed that small amount of Ce (0.6%) into Cu-
14Al-4.5Fe coating could improve diffusion between
the coatings and substrate, and refined the
microstructure of the coating. The addition of 0.6wt %
Ce tended to improve the metallurgical bonding
between the coatings and the commercial carbon 45#
steel substrate (Wensheng et al, 2011). in another
research Hussein et al, 2012 find out the effect of Al
with and without addition of cerium ( 0.5 wt%) were
simultaneously co-deposited on austenitic stainless
steel (AISI 316L) substrates by pack-cementation
process and exposed to 50wt.%
NaCl+50wt.%Na2SO4 salt environment at 750C° for
120h. The results showed that both coated systems
reveal good cyclic oxidation resistance as compared to
uncoated one. Also, it was evident that cerium
improved the hot corrosion resistance of the silicon
modified aluminide coated 316L substrates. Gond et al,
2012 worked on NiCrAlY(bond coat) and Yttria-
Stabilised Zirconia (top coat) coatings deposited on a
T-91 boiler steel with the help of plasma spray
process. Hot corrosion studies were conducted on
uncoated as well as plasma spray coated specimens
in air as well as salt (75wt. % Na2SO4 + 25wt. %
NaCl) at 900°C under cyclic conditions. XRD,
SEM/EDAX results showed that resistance to
corrosion enhances significantly which can be
attributed to formation of zirconium oxides (ZrO2)
and yttrium oxide (Y2O3). Mudgal et al, 2014
examined that D-gun sprayed Cr3C2-25(NiCr)
coatings deposited on superni 718, superni 600 and
superco 605 substrates with and without the addition
of 0.4wt% ceria powder. Hot corrosion test were runs
in 40%Na2SO4-40%K2SO4-10%Nacl-10%KCl
environment at 900ºC for 100 cycles. FESM, EDS
and XRD techniques result shows that addition of
ceria enhanced the adherence of oxide to the coating
and reduce overall weight gain. Cr3C2-(NiCr) +0.2
wt.% zirconium powder was sprayed on Superni 718
alloy by D-gun technique. The bare and coated alloys
were tested under Na2SO4 + K2SO4 + NaCl + KCl
and Na2SO4 + NaCl environment. It was found that
Cr3C2-NiCr coating proves to be beneficial in providing
better corrosion resistance to Superni 718 under molten
salt environment. Further Addition of 0.2wt.%Zr in
Cr3C2-25%(NiCr) coating greatly reduced the
oxidation rate as well as improved the adherence of
oxide scale to the coating surface during the time of
corrosion (Mudgal et al, 2014).
CONCLUSIONS
It can be concluded that rare earth elements play an
important role in the microstructual properties of the
coating and consequently in its oxidation resistance.
Rare earth elements can improve the apparent thermal
expansion coefficient of the coating and mitigate the
thermal expansion mismatch between the coating and
substrate. Hence, it can decrease the thermal stress, and
thereby improve the spallation resistance and the
durability of coating in high-temperature service. This
can lead to the improvement of fracture toughness and
tolerance to cracking and spallation of coating.
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6. TEQIP-II Sponsored National Conference on “Latest Developments in Materials, Manufacturing and Quality
Control” on 19-20th
February, 2015 (ISBN 978-93-5196-055-3)
Department of Mechanical Engineering, Giani Zail Singh Punjab Technical University Campus, Bathinda Page 297
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