Friction and Wear Characteristics of Calophyllum Inophyllum and

Moringa Oleifera Biodiesel Blends

M. H. Mosarof

, A. S. Silitonga

, A. H. Sebayang

Jassinnee Milano

Abd. Halim Shamsuddin

, H. H. Masjuki

, M. A. Kalam

and Burhanuddin Tarigan

Department of Mechanical Engineering, Faculty of Engineering, University of Malaya,50603, Kuala Lumpur, Malaysia

Department of Mechanical Engineering, Politeknik Negeri Medan, 20155 Medan, Indonesia

Department of Mechanical Engineering, College of Engineering, University Tenaga National, Kajang, Malaysia

Institute of Sustainable Energy, Universiti Tenaga Nasional, Kajang, Malaysia

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

______________________________

https://orcid.org/ 0000-0003-3369-9324

https://orcid.org/0000-0002-0065-8203

https://orcid.org/0000-0002-0810-7625

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

 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

iCAST-ES 2021 - International Conference on Applied Science and Technology on Engineering Science

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

KOH/

D664 0.072 0.22 0.24 0.41 0.19 0.20 0.287

Oxidation stabilit

h EN 15751 35 27.70 25.19 2.53 108.6 91.4 26.4

Flash

oint

℃

D93 68.5 72.3 73.1 92.6 79.5 82.1 150.6

Calorific value MJ/k

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

(

)

×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

Value

Loa

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

40 ℃ Temperature

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

isc

sity

(mm

/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 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

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 eﬀect 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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