Friction and Wear Characteristics of Calophyllum Inophyllum and
Moringa Oleifera Biodiesel Blends
M. H. Mosarof
1a
, A. S. Silitonga
2b
, A. H. Sebayang
2c
,
Jassinnee Milano
3d
,
Abd. Halim Shamsuddin
4
, H. H. Masjuki
5
, M. A. Kalam
1
and Burhanuddin Tarigan
2
1
Department of Mechanical Engineering, Faculty of Engineering, University of Malaya,50603, Kuala Lumpur, Malaysia
2
Department of Mechanical Engineering, Politeknik Negeri Medan, 20155 Medan, Indonesia
3
Department of Mechanical Engineering, College of Engineering, University Tenaga National, Kajang, Malaysia
4
Institute of Sustainable Energy, Universiti Tenaga Nasional, Kajang, Malaysia
5
Department of Mechanical Engineering, Kulliyyah of Engineering International Islamic University Malaysia,
Kuala Lumpur, Malaysia
abdhalim@uniten.edu.my, masjuki@iium.edu.my, kalam@um.edu.my, burhanuddintarigan05@gmail.com
Keywords: Calophyllum Inophyllum, Moringa Oleifera, Biodiesel, Triborheometer, Tribology.
Abstract: This study is conducted to investigate the friction and wear characteristics of Calophyllum inophyllum and
Moringa oleifera biodiesel-blends using a four-ball triborheometer. The tests were conducted at different loads
(40, 50, 70, and 80 kg) at a constant speed of 1800 rpm and room temperature of 27 °C over a 300-s period.
The average coefficient of friction of diesel is 24.93% higher than that for the blend containing 10 vol% of
Moringa oleifera biodiesel (MB10). Moringa oleifera biodiesel contains 74% of oleic acid, which can reduce
friction from metal contacting surfaces. The biodiesels result in lower frictional energy loss and minimum
wear on the metal surfaces. The blends containing 20 vol% of Calophyllum inophyllum biodiesel and Moringa
oleifera biodiesel (CIB20 and MB10) show the best results with the lowest coefficient of friction, offering
excellent lubricating properties.
1 INTRODUCTION
Friction is a phenomenon that occurs when two
contacting surfaces are in relative motion, which has
a significant effect on fuel efficiency. Friction is of
interest to vehicle and engine manufacturers as well
as lubricant manufacturers because friction leads to
wear, where the minute surface asperities of the two
contacting surfaces become locked and grind against
one another, resulting in the removal of material.
Wear can also occur due to the electromagnetic forces
between the molecules of the two contacting surfaces,
as well as chemical reactions between the contacting
surfaces and the environment. Many studies have
been carried out to reduce friction and thus, minimize
wear of contacting surfaces such as the development
of surface coatings (Arslan et al., 2015),
modifications of the surface textures (Ahmed et al.,
2016; Arslan et al., 2016), the use of lightweight
materials (Quazi et al., 2016), and the improvement
of lubrication formulations.
Lubricant is a substance (which can be solid, liquid,
or gas) used to form a barrier between the asperities
of the contacting surfaces in order to minimize
friction and wear. Various additives have been used
to (1) maintain the temperature sensitivity of the
lubricant viscosity, (2) protect the contacting surfaces
from friction and wear by the formation of a
protective film, (3) reduce solid-to-solid friction by
making the surfaces more slippery, (4) keep the
contacting surfaces clean and free from debris, and
(5) maintain the properties of the lubricant within
acceptable levels. In recent years, lubricant additives
derived from ash in the exhaust stream have become
important in the field of advanced diesel engines
equipped with emission aftertreatment control
systems (Priest and Taylor, 2000).
Friction in internal combustion engines arises from
_
______________________________
a
https://orcid.org/ 0000-0003-3369-9324
b
https://orcid.org/0000-0002-0065-8203
c
https://orcid.org/0000-0002-0810-7625
d
https://orcid.org/0000-0001-7130-072X
Mosarof, M., Silitonga, A., Sebayang, A., Milano, J., Shamsuddin, A., Masjuki, H., Kalam, M. and Tarigan, B.
Friction and Wear Characteristics of Calophyllum Inophyllum and Moringa Oleifera Biodiesel Blends.
DOI: 10.5220/0010957900003260
In Proceedings of the 4th International Conference on Applied Science and Technology on Engineering Science (iCAST-ES 2021), pages 1003-1010
ISBN: 978-989-758-615-6; ISSN: 2975-8246
Copyright
c
2023 by SCITEPRESS Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)
1003
the shearing of oil films between the various working
surfaces such as fuel pumps, reciprocating pistons,
piston cylinders, piston liners, fuel injectors, fuel
depositors, and piston rings. Therefore, lubrication
plays an important role to minimize friction and wear
of engine components (Taylor, 1998). Lubrication
protects the engine components from damage caused
by friction and wear. The frictional energy losses
caused by the moving engine components will
eventually increase the fuel consumption of the
engine and reduce engine life, which indicates the
importance of lubrication (Tung and McMillan,
2004). However, the presence of a lubricant may lead
to undesirable changes in the fuel properties such as
an increase in the fuel kinematic viscosity and
density, which in turn, leads to an increase in the
absorbency of water and corrosion of the engine
components. In addition, lubricant carries solid
contaminants from combustion, some of which
cannot be filtered, and this leads to plugging of the
filters (i.e., the contaminants adhere to and clog the
filters) and coking of the fuel injectors (i.e., the
chemically degraded lubricant components and
combustion products adhere to the surface of the fuel
injectors) (Fazal et al., 2011).
Nowadays, there is great interest in investigating the
lubricity of biodiesels, and not just the potential of
biodiesels as a fossil fuel alternative, which helps
eliminate the use of a lubricant. According to Serrano
et al. (2012), biodiesels provide lubrication to the fuel
pumps and injectors. Dharma et al. (2016) and
Silitonga et al. (2019) found that biodiesels have good
fuel lubricity in addition to good engine perfromance
and lower exhaust emissions compared with diesel.
Likewise, Hu et al. (2005) found that biodiesels have
good lubricity, which helps in ensuring smooth
movement of engine parts. Van Gerpen et al. (1999)
compared the lubrication characteristics of soybean
oil and soybean biodiesel and found that the soybean
biodiesel has favourable tribological characteristics.
Several studies have been carried out to evaluate the
lubricating properties of the biodiesel blends, and
there is a decrease in the coefficient of friction,
depending on the type of biodiesel. Better tribological
characteristics have been observed for blends with
different percentages of additive (Silitonga et al.,
2013). Fazal et al. (2013) investigated the tribological
characteristics of palm biodiesel and its blends (B10,
B20, B50, and B100) at a constant load of 40 kg,
temperature of 75 , and different rotational speeds
(600, 900, 1200, and 1500 rpm). They found that both
friction and wear were reduced with a higher
concentration of biodiesel in the fuel blend. Much
effort has been made to investigate the potential of
using Calophyllum inophyllum biodiesel as a
lubricant despite its higher unsaturated fatty acid
content (Milano et al., 2018), higher viscosity and
density (Ong et al., 2019), lower oxidation stability,
higher acid value, and higher flash point compared
with biodiesels produced from other non-edible plant-
based oils (Mosarof et al., 2016). Calophyllum
inophyllum and Moringa oleifera biodiesels have
been proven to have a higher viscosity, flash point,
and acid value, and better lubricity than diesel and
other biodiesels (Silitonga et al., 2013).
Previous studies (Fazal et al., 2013; Habibullah et al.,
2015) have been carried out to investigate the
tribological characteristics of palm and Calophyllum
inophyllum biodiesel blends. However, to date, there
are no studies focused on the friction and wear
characteristics of Calophyllum inophyllum and
Moringa oleifera biodiesel blends, which is worthy of
investigation. Therefore, the objective of this study is
to investigate the friction and wear characteristics of
Calophyllum inophyllum and Moringa oleifera
biodiesel blends. It is believed that this study will
provide insight on the potential of Calophyllum
inophyllum and Moringa oleifera biodiesel blends as
a lubricant, thereby eliminating the need for an
additional lubricant in diesel engines.
2 MATERIALS AND METHODS
2.1 Biodiesel Production
The crude Callophyllum inophyllum and Moringa
oleifera oils were initially heated in a vessel at ~100
for approximately 15 min order to remove moisture,
which can reduce the biodiesel yield. The crude
Calophyllum inophyllum and Moringa oleifera oils
were then left to cool to below 60 before adding a
catalyst-alcohol solution, which was prepared by
dissolving 1 wt% of potassium hydroxide into 25
vol% methanol for the transesterification reaction.
The transesterification reaction was conducted for 2 h
at a stirring speed of 1000 rpm. After the
transesterification reaction, the mixture was poured
into a separatory funnel. Two layers eventually
formed in the separatory funnel, where the top layer
was biodiesel and the bottom layer was a mixture of
glycerine and other impurities. The bottom layer was
removed by opening the stopcock of the separatory
funnel. The biodiesel was then collected and washed
with distilled water several times to remove the
remaining impurities. The purified biodiesel was then
dried using a rotary evaporator and then filtered with
filter paper. The Calophyllum inophyllum biodiesel
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1004
Table 1: Physicochemical properties of diesel, calophyllum inophyllum biodiesel, moringa oleifera biodiesel, and
calophyllum inophyllum and moringa oleifera biodiesel blends.
Property Unit Standard Diesel CIB10 CIB20 CIB100 MB10 MB20 MB100
Kinematic viscosity
at 40
mm2/s D445 34.926 37.318 37.986 49.762 35.611 36.924 51.338
Density at 15
kg/m3 D4052 857.6 859.5 860.4 887.2 859.1 860.3 877.6
Acid value m
g
KOH/
g
D664 0.072 0.22 0.24 0.41 0.19 0.20 0.287
Oxidation stabilit
y
h EN 15751 35 27.70 25.19 2.53 108.6 91.4 26.4
Flash
p
oint
D93 68.5 72.3 73.1 92.6 79.5 82.1 150.6
Calorific value MJ/k
g
D240 45.6 44.48 43.86 39.17 44.3 43.6 39.8
(CIB100) and Moringa oleifera biodiesel (MIB100)
were then blended with diesel to produce biodiesel
blends. The following blends were prepared: (1)
CIB10 (10 vol% of Calophyllum inophyllum
biodiesel + 90 vol% of diesel), (2) CIB20 (20 vol% of
Calophyllum inophyllum biodiesel + 80 vol% of
diesel), (3) MB10 (10 vol% of Moringa oleifera
biodiesel + 90 vol% of diesel), and (4) MB20 (20
vol% of Moringa oleifera biodiesel + 80 vol% of
diesel).
2.2 Physicochemical Properties of
Biodiesel
The physicochemical properties (kinematic viscosity
at 40 °C, density at 15 °C, flash point, acid value,
oxidation stability, flash point, and calorific value) of
the CIB10, CIB20, MB10, and MB20 blends were
determined according to standard methods and the
results were compared with those for diesel, CIB100,
and MB100, as shown in Table 1.
2.3 Test Procedure
The test fuels were then tested for both sliding and
rolling contacts. The sliding contact tests were
conducted using a four-ball triborheometer (Model:
TR-30H), as shown in Fig. 1. The test balls were
cleaned with toluene to remove oil stains and
impurities and then dried with a clean paper towel.
For each test, 10 mL of the test fuel was poured into
a steel cup to cover the stationary balls and then the
steel cup was placed into the four-ball triborheometer.
The upper steel ball was rotated against the three
lower stationary balls, forming a tetrahedron. The
frictional data were collected using software installed
in a desktop computer. Four loads were used for the
tests: 40, 50, 70, and 80 kg. The speed of the rotating
ball was set at a constant speed of 1800 rpm at room
temperature (27 °C) for 5 min. The operating
conditions were carried out according to ASTM
D2596 and ASTM D2783 standards, as tabulated in
Table 2. The data were used to calculate the
coefficient of friction (CoF) using Eq. 1 (Liaquat et
al., 2013).
Coefficient of friction, µ =
Friction torque
(
kg⋅mm
)
× √6 𝑇√6
=
3×Applied load
(
kg
)
×Distance (mm) 3𝑊𝑟 (1)
where 𝑇 is the frictional torque in kilogramme
millimetres (kg-mm), 𝑊 is the applied load in
kilogrammes (kg) and 𝑟 is the distance measured from
the centre of the lower ball’s surface to the rotation
axis in millimetres (mm). Here, 𝑟 is 3.67 mm.
Figure 1: Four-ball triborheometer.
Friction and Wear Characteristics of Calophyllum Inophyllum and Moringa Oleifera Biodiesel Blends
1005
Table 2: Operating conditions for the four-ball
triborheometer.
2.4 Wear Evaluation
The four-ball triborheometer was used to assess the
lubricity of the Calophyllum inophyllum and
Moringa oleifera biodiesel blends. An optical
microscope (Model: C200, IKA, UK) with a
resolution of 0.01 mm was used to measure the wear
scar diameter of the test balls. The wear scar images
of the test balls were captured, and the wear scar
diameter was measured using the computer software.
After each test, the average wear scar diameters of all
the test balls were determined. Calculating total
magnification of microscope requires knowing the
magnification of the ocular (eyepiece) and of the
objective lens being used. The wear was evaluated for
all of the test balls in this study. The wear scar
diameters of the three stationary balls were measured,
and the average value was determined.
3 RESULTS AND DISCUSSION
3.1 Kinematic Viscosity
The kinematic viscosity of a lubricant is strongly
dependent on its composition, with higher kinematic
viscosity being associated with higher molecular
weight. The lubrication effect on metal contacting
surfaces is determined by the viscosity of the
lubricant. Kinematic viscosity can increase or
decrease during engine operation, which determines
the properties of the lubricant. The products of
condensation and polymerization reactions, which
take place under high thermal stress of the lubricant,
as well as the presence of oxidation products
contributes to the increase in kinematic viscosity. It
shall be noted that high engine speeds enhance fuel
dilution, which leads to a significant decrease in the
kinematic viscosity, resulting in more wear.
However, friction is slightly reduced, which is
probably due to the drop in kinematic viscosity
(Kalam et al., 2012). The wear caused by soot occurs
through abrasive wear mechanism, where the soot
antagonistically interacts with the protective
tribofilms formed by the anti-wear additives and
worsens the wear of engine components. The
kinematic viscosities of the Calophyllum inophyllum
and Moringa oleifera biodiesel blends and diesel at 40
and 100 °C are shown in Fig. 2. The MB100 biodiesel
has a higher kinematic viscosity than diesel and
CIB100 biodiesel. Viscosity and frictional forces can
develop by the shearing of the viscous lubricant.
Corrosive wear can occur on the bearing surfaces due
to the presence of lubrication. Adhesive wear is
possible at the initial and end processes. Corrosive
wear can be reduced through lubricant precipitation
and formation of films on the bearing surface (Serrato
et al., 2007). Therefore, a lower kinematic viscosity
leads to more wear on the sliding surface, whereas a
higher kinematic viscosity causes frictional losses
during sliding of the metal components. From Table
1, the MB100 biodiesel has a higher kinematic
viscosity compared to diesel and other biodiesel
blends. A higher viscosity index indicates less
viscosity variation with respect to changes in
temperature, whereas a lower viscosity index
indicates high changes in viscosity with respect to
temperature. These results can be attributed to the
triglyceride compounds in the vegetable oils while
sustaining stronger intermolecular interactions when
the temperature is rising (Ahmed et al., 2014). Hence,
the Moringa oleifera biodiesel blends in this study are
found to reduce more wear on the metal contacting
surfaces than Calophyllum inophyllum biodiesel
blends. The results indicate that the Moringa oleifera
biodiesel blend is suitable for boundary lubrication
applications.
3.2 Friction
Friction is the force resisting the relative motion of
two mating surfaces in contact with a fluid. The two
sliding surfaces move relative to each other, and the
friction between the mating surfaces converts the
kinetic energy into heat or thermal energy. In this
study, the CoF values are presented with respect to
the running-in period and steady-state condition. The
running-in period is the period where the test balls are
first brought into contact and slid over one another,
and it is a transient event. The CoF values
Machine operating conditions
Paramete
r
Value
Loa
d
40, 50, 70 and 80 k
Speed 1800 rpm
Temperature Ambient (27 °C)
Test duration 5 min
Specifications of the test balls
Materials Carbon-chromium steel (SKF)
Size (𝟇)
12.7 mm
Hardness 62 HRc
Elemental
composition
85.06% Fe, 10.2% C, 0.12% P,
0.45% Si, 1.46% Cr, 0.07% S,
0.42% Mn, 2.15% Zn, 0.06% Ni,
Surface roughness 0.1 µm (centre line average)
iCAST-ES 2021 - International Conference on Applied Science and Technology on Engineering Science
1006
60
50
40
30
20
10
0
40 Temperature
o
C 100
Figure 2: Kinematic viscosities of diesel, Calophyllum inophyllum biodiesel, Moringa oleifera biodiesel, Calophyllum
inophyllum and Moringa oleifera biodiesel blends at a temperature of 40 and 100 °C.
of diesel and Calophyllum inophyllum and Moringa
oleifera biodiesel blends during the running- in period
of 10 s under a load of 80 kg are shown in Fig. 3. The
CoF is one of the key parameters to analyse the
tribological characteristics of the test fuels. It can be
seen that within the 10-s period, the CoF is unstable
and exhibits a higher magnitude. The maximum CoF
values are found to be 0.5454, 0.4933, 0.5126, and
0.4959 for the CIB10, CIB20, MB10, and MB20
blends, respectively. The CoF of the diesel fuel is
0.5316 and the highest CoF is obtained for the CIB10
blend, with a value of 0.5454. The CoF values of the
characteristics of test fuels for steady-state condition
under a load of 80 kg load is shown in Fig. 4. In
steady-state condition, diesel has a higher CoF and
the value eventually stabilizes after 292 s. The CIB20
blend shows a similar CoF trend as diesel. The CoF
trends are similar for the CIB10, MB10, and MB20
blends. In general, the Moringa oleifera blends have
a lower CoF compared with diesel and Calophyllum
inophyllum blends in steady-state condition. The
Calophyllum inophyllum and Moringa oleifera
blends have a lower CoF than diesel. Diesel has a
slightly higher CoF than the CIB10, CIB20, MB10,
and MB20 blends by 13.47, 4.21, 24.93, and 23.48%,
respectively. The MB10 blend has the lowest CoF
compared with the other fuel blends. The lubricating
ability of the fuels due to their very low viscosity is
mostly dependent on their boundary film forming
properties. At the same time, the sensitivity of
biodiesel towards oxidation may vary and is mainly
dependent on the feedstock and presence of natural
antioxidants (Zulkifli et al., 2013). The high oleic acid
content of Moringa oleifera biodiesel is the main
reason for the lower friction characteristics of the
Moringa oleifera blends. The CIB20 blend results in
more friction, especially at a high applied load.
Therefore, biodiesel (which has fatty compounds)
possesses better lubricity than hydrocarbons and the
lubricity somewhat improve with the chain length and
presence of double bonds (Knothe and Steidley,
2005; Kumar et al., 2014). The Moringa oleifera
biodiesel and its blends reduce the friction caused by
two metal contacting surfaces compared with the
diesel and Calophyllum inophyllum blends. The
lubrication performance of Moringa oleifera
biodiesel blends decreases with an increase in the
load applied to the contacting surfaces. Therefore,
Moringa oleifera biodiesel has lower friction
characteristics in running-in period and steady-state
condition under a high applied load. For longer
periods, oxidation may occur, which causes fuel
debasement and results in a higher steady-state CoF.
Biodiesel is susceptible to oxidation due to the
presence of unsaturated fatty acids in its moiety.
These reactions are accelerated in the presence of
oxygen and high temperatures, which may alter the
lubrication characteristics (Agarwal, 1999; Kumar et
al., 2014).
Diesel CIB100 MB10 MB20 MB100
Kin
ematic
v
isc
o
sity
(mm
2
/s)
Friction and Wear Characteristics of Calophyllum Inophyllum and Moringa Oleifera Biodiesel Blends
1007
0,6
0,5
0,4
0,3
0,2
0,1
0
0 2 4 6 8 10
Time (s)
Figure 3: Friction characteristics of diesel and Calophyllum inophyllum and Moringa oleifera biodiesel blends during the
running-in-period.
Figure 4: Friction characteristics of diesel and Calophyllum inophyllum and Moringa oleifera biodiesel blends during steady-
state condition.
3.3 Wear Scar Diameter (WSD)
The wear scar diameter (WSD) was measured by an
optical microscope. The morphologies of the worn
surface reveal that the nanoparticle concentrations
improve the friction and wear properties of liquid
paraffin. The WSDs of the surfaces lubricated with
the test fuels are shown in Fig. 5. The average WSDs
of the CIB10, CIB20, MB10, and MB20 blends are
higher by approximately 9.38, 39.30, 3.36, and
2.27%, respectively, relative to that for diesel. The
smallest WSD is obtained for the CIB20 blend
regardless of load, and the WSD is significantly lower
compared with those for the CIB10, MB10, and
MB20 blends. The result indicates that diesel results
in the largest WSD for all load conditions. In general,
the larger the WSD, the more severe the wear
(Syahrullail et al., 2013). The WSD is determined by
the applied load. The scar will be larger as the load
pressurizing the metal contacting surfaces increases,
resulting in more wear. Biodiesels also have a high
oxygen content, which helps to reduce friction and
wear of the steel contacting surfaces. The
susceptibility of biodiesel to oxidation upon exposure
to oxygen is due to its unsaturated fatty acid chains,
especially those with bis-allylic methylene moieties.
The bis-allylic protons are highly susceptible to
radical attacks and subsequently, the molecules
undergo oxidation. It can be deduced that the
biodiesels enhance the lubrication property through
the development of lubricating films. The efficiency
of the lubricant and the film formed is dependent on
the fatty acid chain length (Havet et al., 2001).
Diesel
MB20
MB10
C
oF
iCAST-ES 2021 - International Conference on Applied Science and Technology on Engineering Science
1008
Figure 5: WSD of biodiesel blends with the variations of load.
4 CONCLUSIONS
Biodiesels can be used as a lubricity enhancer,
hydraulic fluid, cutting fluid, drilling fluid, viscosifier,
and chain oil at moderate temperatures. A four-ball
tribometer is a common research rig used in the
lubricant industry to assist in manufacturing new
lubricants and greases. This study was conducted to
investigate the friction and wear characteristics of
Calophyllum inophyllum and Moringa oleifera
biodiesel blends. The findings of this study raise a
serious question on the utilization of biodiesel blends
in compression-ignition engine parts, especially for
long-term applications. In this regard, it is imperative
to add environmentally friendly modifiers into
biodiesels to mitigate the eect of oxidative
instability. Moreover, the biodiesel blends produce
more abrasive wear whereas diesel produce adhesive
wear. Powertrain manufacturers and additive
suppliers can make use of the findings of this study to
improve powertrain system efficiency, product
performance, and fuel economy. Biodiesels can
improve engine efficiency, powertrain durability, and
vehicle performance in the engine life due to their
lower friction and wear characteristics.
ACKNOWLEDGEMENTS
The authors graciously acknowledge the financial
support provided by the Politeknik Negeri Medan,
Medan, Indonesia (grant no.:
B/188/PL5/TU.01.05/2021). The authors also wish to
express their greatest appreciation to Institute of
Sustainable Energy, Universiti Tenaga Nasional
(UNITEN) for supporting this research.
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