**3. Results and discussion**

## **3.1. Friction and wear characterization**

Fig. 3 show the pins wear as a function of sliding time for various Jatropha oil blended biolubricants. At the operating condition of 2000 rpm and 30 N loads, the linear pin wear varied from 0.02 to 0.05 mm. It is observed that the maximum wear occurred in the beginning of the experiment using biolubricants. It can be seen form the Fig. 3, that the maximum wear was occurred for JBL40 while the minimum wear was observed for JBL10. The results can be attributed to the maximum ability of the JBL 10 biolubricant film to protect metal to metal contact and keep consistency throughout the operation time while this ability is least for JBL40. It can also be seen that the rate of wear throughout the time is almost identical for the biolubricants whereas, the reducing trend is observed for the base lubricant. At the beginning of the test, the wear rate was very fast for few minutes which are known running-in period. During this period, the asperities of the sliding surface are cut off and the contact area of the sliding surface grows to an equilibrium size. After certain period of time, equilibrium wear condition between pins and disc surface was established and thereby the wear rate became steady. It can be identified from the Fig. 3 that the biolubricants JBL 30, JBL 40 and JBL 50 showed high wear while base lubricant, JBL 10 and JBL 20 impart low pin wear and their values are nearly same with each other.

Fig. 4 sows the loos of material from the pin for different percentage of biolubricant samples. It seems quite clear that the loos of material from the pins are highest for 50% biolubricant and that is least for base lubricant. It can also be interpreted that the loos of material from JBL 10 is almost similar with base lubricant and this loos of material is increasing with increasing biolubricant percentages.

**Figure 3.** The linear pin wear as a function of sliding time for various Jatropha oil biolubricants.

**Figure 4.** Loos of material form the pin for various biolubricant percentages

#### **3.2. Coefficient of friction**

138 Tribology in Engineering

specimen

**2.4. Lubricant analyses** 

**3. Results and discussion** 

**3.1. Friction and wear characterization** 

for both 40°C and 100°C controlled bath temperatures.

Pin Disc

**Figure 2.** Schematic diagram of the experimental set up and dimensions geometry's of pins and disc

Multi element oil analyzer (MOA) was used to measure the wear elements in the lubricants by Atomic Emission Spectroscopy (AES). Whereas, for viscosity measurement the automatic Anton Paar viscosity meter was used with standard ASTM D 445. Viscosity was measured

Fig. 3 show the pins wear as a function of sliding time for various Jatropha oil blended biolubricants. At the operating condition of 2000 rpm and 30 N loads, the linear pin wear varied from 0.02 to 0.05 mm. It is observed that the maximum wear occurred in the beginning of the experiment using biolubricants. It can be seen form the Fig. 3, that the maximum wear was occurred for JBL40 while the minimum wear was observed for JBL10. The results can be attributed to the maximum ability of the JBL 10 biolubricant film to protect metal to metal contact and keep consistency throughout the operation time while this ability is least for JBL40. It can also be seen that the rate of wear throughout the time is almost identical for the biolubricants whereas, the reducing trend is observed for the base lubricant. At the beginning of the test, the wear rate was very fast for few minutes which are known running-in period. During this period, the asperities of the sliding surface are cut off and the contact area of the sliding surface grows to an equilibrium size. After certain period of time, equilibrium wear condition between pins and disc surface was established and thereby the wear rate became steady. It can be identified from the Fig. 3 that the biolubricants JBL 30, JBL 40 and JBL 50 showed high wear while base lubricant, JBL 10 and

JBL 20 impart low pin wear and their values are nearly same with each other.

Fig. 4 sows the loos of material from the pin for different percentage of biolubricant samples. It seems quite clear that the loos of material from the pins are highest for 50% biolubricant and that is least for base lubricant. It can also be interpreted that the loos of material from Fig.5 shows the friction coefficient plotted against the sliding time for various Jatropha oil biolubricants. The results of the figure depict that the lubricant regime that occurred during the experiment were the boundary lubrication with the value of friction coefficient for boundary lubricant in the range of 0.001 to 0.2 except for 50% of Jatropha oil biolubricant. For JBL 0, it can be seen that the coefficient of friction is highest at the beginning and then it fell down rapidly and became least with compared to all tested samples after half of the operation time. The biolubricant percentage from 10 to 40% showed likely to be similar coefficient of friction (µ) which is almost 0.15. Whereas, the 50 % added Jatropha oil showed the coefficient of friction value of ~ 0.225 throughout the operation time. The fatty acid component of biolubricants formed multi and mono layer on the surface of the rubbing zone and make stable film to prevent the contact between the surfaces.

Development of Eco-Friendly Biodegradable Biolubricant Based on Jatropha Oil 141

of temperature is high while the changing rate is low for second half of the operation time. It can be explained that during second half of the operation time heat produced in the lubricant

Viscosity is the measure of resistance to flow [18]. Table 2 shows the viscosity grade requirement for the lubricants set by International standard organization (ISO), while Fig. 7 shows the viscosity of tested different biolubricant samples. The comparison of the results of the Fig.7 with that of ISO grade illustrates that in case of 40°C, the biolubricants JBL 40 and JBL 50 did not meet the ISO VG100 requirement. On the other hand all other biolubricants meet the entire ISO grade requirement as well. It can also be noted that the viscosity of

Kinematic viscosity ISO VG32 ISO VG46 ISO VG68 ISO VG100 @ 40°C >28.8 >41.4 >61.4 >90 @ 100°C >4.1 >4.1 >4.1 >4.1

due friction and the heat dissipated to the outside is nearly equilibrium.

biolubricants are much higher than standard requirements

**Figure 7.** The viscosity of various percentages of biolubricants at 40°C and 100°C

The aim of the elemental analysis by using Multi Element Oil Analyzer (MOA) is to determine the kinds and amount of metal contain in the lubricating oil. Table 3 shows the elemental analysis of tested lubricant sample by using MOA before and after the test. From the Table 3, it can be noticed that the base lubricant contains higher Silver (Ag), Zinc (Zn), Phosphorus (P), Magnesium (Mg) and Boron (B) with in high percentage compared to other element while, in pure Jatropha oil, Calcium (Ca) and Silicon (Si) are the higher element compared with other element. Some of the elements are used as additive in the lubricant to ameliorate the lubricants tribological properties. From the results, increasing number of iron

0 10 20 30 40 50 60

**40°C 100°C**

Biolubricant percentages (%)

**Table 2.** ISO Viscosity grade requirement [19]

0

50

100

Viscosity (cSt)

150

200

**3.5. Elemental analysis** 

**3.4. Viscosity** 

**Figure 5.** The Coefficient of friction as a function of sliding time for various Jatropha oil biolubricants

#### **3.3. Lubricants temperature**

Fig.6 shows the relationship of the averages oil temperature of varies percentage of Jatropha oil biolubricants with the sliding time. The rise of temperature during the running hour (1 h) for JBL 10 is least while the highest change is occurred for JBL 40 which is 11.77°c and 25.49°C respectively. The temperature rises of other samples are of 12.8°C, 18.65°C and 13. 66°C for 20% 30% and 50% Jatropha oil added biolubricants respectively. The results of the Fig. 6 show that the JBL 10 has the highest potentiality to retain its property without much changing its temperature. From the figure it can also be interpreted that up to 30 minutes rate of change

**Figure 6.** The Lubricant Temperature as a function of sliding time for various Jatropha oil biolubricants

of temperature is high while the changing rate is low for second half of the operation time. It can be explained that during second half of the operation time heat produced in the lubricant due friction and the heat dissipated to the outside is nearly equilibrium.

#### **3.4. Viscosity**

140 Tribology in Engineering

**3.3. Lubricants temperature** 

0

10

20

30

Temperature (°C)

40

50

60

0

0.05

0.1

0.15

COF (

)

0.2

0.25

0.3

component of biolubricants formed multi and mono layer on the surface of the rubbing zone

JBL 0 JBL 10 JBL 20 JBL 30 JBL 40 JBL 50

JBL 0

JBL 10

JBL 20

JBL 30

JBL 40

JBL 50

**Figure 5.** The Coefficient of friction as a function of sliding time for various Jatropha oil biolubricants

0 600 1200 1800 2400 3000 3600

Time (sec.)

Fig.6 shows the relationship of the averages oil temperature of varies percentage of Jatropha oil biolubricants with the sliding time. The rise of temperature during the running hour (1 h) for JBL 10 is least while the highest change is occurred for JBL 40 which is 11.77°c and 25.49°C respectively. The temperature rises of other samples are of 12.8°C, 18.65°C and 13. 66°C for 20% 30% and 50% Jatropha oil added biolubricants respectively. The results of the Fig. 6 show that the JBL 10 has the highest potentiality to retain its property without much changing its temperature. From the figure it can also be interpreted that up to 30 minutes rate of change

**Figure 6.** The Lubricant Temperature as a function of sliding time for various Jatropha oil biolubricants

0 1000 2000 3000 4000

Time (sec**.)**

and make stable film to prevent the contact between the surfaces.

Viscosity is the measure of resistance to flow [18]. Table 2 shows the viscosity grade requirement for the lubricants set by International standard organization (ISO), while Fig. 7 shows the viscosity of tested different biolubricant samples. The comparison of the results of the Fig.7 with that of ISO grade illustrates that in case of 40°C, the biolubricants JBL 40 and JBL 50 did not meet the ISO VG100 requirement. On the other hand all other biolubricants meet the entire ISO grade requirement as well. It can also be noted that the viscosity of biolubricants are much higher than standard requirements


**Table 2.** ISO Viscosity grade requirement [19]

**Figure 7.** The viscosity of various percentages of biolubricants at 40°C and 100°C

#### **3.5. Elemental analysis**

The aim of the elemental analysis by using Multi Element Oil Analyzer (MOA) is to determine the kinds and amount of metal contain in the lubricating oil. Table 3 shows the elemental analysis of tested lubricant sample by using MOA before and after the test. From the Table 3, it can be noticed that the base lubricant contains higher Silver (Ag), Zinc (Zn), Phosphorus (P), Magnesium (Mg) and Boron (B) with in high percentage compared to other element while, in pure Jatropha oil, Calcium (Ca) and Silicon (Si) are the higher element compared with other element. Some of the elements are used as additive in the lubricant to ameliorate the lubricants tribological properties. From the results, increasing number of iron


Development of Eco-Friendly Biodegradable Biolubricant Based on Jatropha Oil 143

(Fe) and aluminum (Al) molecules are observed with increasing percentages of Jatropha oil in the base lubricants. The source of Fe and Al are mainly cast iron plate and aluminum plate. Due to lower hardness of the aluminum pin the extraction of aluminum molecule form the pin is much higher than cast iron plate. The changes of other elements were observed before and after the test. It is clear from the elemental analysis that, most of elements were decreased after

There are various types of wear in the mechanical system, such that abrasive wear, adhesive wear, fatigue wear and corrosive wear. Since the lubricant regime occurred in this experiment was boundary lubrication thereby, abrasive wear, adhesive wear, fatigue wear and corrosive wear were observed in to the rubbing zone. All these wears mechanisms found in this experiments but the mostly the wear phenomenon were abrasive and adhesive wear. This is because of an existence of straight grooves in the direction of the sliding direction. These grooves exist because the asperities on the hard surface (disc) touched the soft surface (pins) and hade a close relationship with the thickness of lubrication film. The optical images of the tested cast iron plate using various types of biolubricants are shown in Fig. 8. Referring to the Fig. 8, it is found that the wear increases with increasing percentage of Jatropha oil in the biolubricants. Reduction of lubricant film thickness leads to the

**Figure 8.** Optical image of the surface of the cast iron plate for different biolubricants (magnification 30

the test, by oxidizing and the chemical interaction among the elements.

surfaces to come closer to each other and cause higher wear.

(a) (b (c)

(d) (e) (f)

×): (a): JBL 0, (b): JBL10, (c): JBL 20, (d): JBL 30, (e): JBL 40, (f): JBL 50

**3.6. Surface texture analysis** 

\*All values are in ppm

**Table 3.** Elemental analysis of tested lubricant sample

#### 142 Tribology in Engineering

(Fe) and aluminum (Al) molecules are observed with increasing percentages of Jatropha oil in the base lubricants. The source of Fe and Al are mainly cast iron plate and aluminum plate. Due to lower hardness of the aluminum pin the extraction of aluminum molecule form the pin is much higher than cast iron plate. The changes of other elements were observed before and after the test. It is clear from the elemental analysis that, most of elements were decreased after the test, by oxidizing and the chemical interaction among the elements.

#### **3.6. Surface texture analysis**

142 Tribology in Engineering

\*All values are in ppm

**Table 3.** Elemental analysis of tested lubricant sample

There are various types of wear in the mechanical system, such that abrasive wear, adhesive wear, fatigue wear and corrosive wear. Since the lubricant regime occurred in this experiment was boundary lubrication thereby, abrasive wear, adhesive wear, fatigue wear and corrosive wear were observed in to the rubbing zone. All these wears mechanisms found in this experiments but the mostly the wear phenomenon were abrasive and adhesive wear. This is because of an existence of straight grooves in the direction of the sliding direction. These grooves exist because the asperities on the hard surface (disc) touched the soft surface (pins) and hade a close relationship with the thickness of lubrication film. The optical images of the tested cast iron plate using various types of biolubricants are shown in Fig. 8. Referring to the Fig. 8, it is found that the wear increases with increasing percentage of Jatropha oil in the biolubricants. Reduction of lubricant film thickness leads to the surfaces to come closer to each other and cause higher wear.

**Figure 8.** Optical image of the surface of the cast iron plate for different biolubricants (magnification 30 ×): (a): JBL 0, (b): JBL10, (c): JBL 20, (d): JBL 30, (e): JBL 40, (f): JBL 50
