Tribological response of fresh and used engine oils 1
1. INDIAN INSTITUTE OF TECHNOLOGY (ISM),
DHANBAD
SEMINAR PRESENTATION ON
TRIBOLOGICAL RESPONSE OF FRESH AND USED
ENGINE OILS:
THE EFFECT OF SURFACE TEXTURING,
ROUGHNESS AND FUEL TYPE.
Presented by: Nagesh Dewangan
M.Tech. 1st Year, MET
Admn. No.:17MT001503
2. Introduction
Internal Combustion Engines (ICEs) are significant source of friction.
Engines are becoming more powerful due to improvement in oil formulation, surface
finishing and development of new materials but friction losses are still high 11.5%.
Major part of friction occurs in bearing (60%) and remaining (40%) in cam, gear and
differential etc.
Boundary Lubrication cause significant loss..
Fig 1: Specific film thickness and Speed vs stroke length
3. Literature Survey
As in case of boundary lubrication, solid lubricants are used such as MoS2, PTFE, Carbon,
Diamond etc.
Surface properties were used to evaluate the effect of surface roughness and texture on
MoS2 formation.
MoS2 is dispersed in the oil as MoDTC.
Formation of MoS2 requires nascent metal surfaces.
Different lubricating oils were used for the experiment.
4. Literature Gap
As simply using Base Oil tries to increase friction due to increase in plasticity.
So, we have to add some material into it so as to reduce friction.
Other oils such as gasoline and ethanol tries to reduce friction but its oxidation is
high.
5. Objective
To find the best lubricant for the lubrication purpose.
To evaluate the effect of new and used oil on engine lubrication.
To find effect of surface texture on lubrication.
6. Method and Material
Tribotests
Oil analysis is done using an Optical Instrument (Ball on Disk arrangement).
Test is carried out for 20min with 3ml of oil on the surface of disc.
Temperature is about 40 OC with 35N of force.
Reciprocating motion of 5mm stroke and 10Hz frequency.
Fig 2: Tribometer Ball on Disk
7. Method and Material
Test Specimens
Ball – AISI 52100 Bearing Steel, Disk – AISI H13 Tool Steel
Smooth and Rough surface finishing of disk.
2D profile within a Hertzian Contact Width (┴ and ═) on the lay.
Tested Lubricants
Base Oil, a Commercial engine oil (5W30-SM),
Used Oils (5W30E22 and 5W30E100).
Main properties are Kinematic viscosity,
Plasticity Index, Specific film thickness, TAN,TBN.
Oil is analysed using Atomic Emission Spectroscopy.
8. Results
Lubrication and Contact Mechanics
Hertzian Contact take place where maximum contact pressure for ideally smooth surface are
under surface hardness. PO=1.51GPa, H=6.42GPa.
Oil Analysis
SM generation oils are tested for fuel economy test.
FEI is tested with reference oil (Base Oil).
Fig. 4. FTIR spectra of 5W30, 5W30E100, 5W30E22,
E100 and E22.
Fig. 3. Real area of contact vs. plasticity index.
9. Results
Friction Coefficient Measurement
COF vs Test Time at temperature 40 OC for smooth and rough surfaces.
Fig 5: Smooth surface: COF versus time Fig 6: Rough surface: COF versus time
10. Discussion
Friction Response: Rough Surface
Mechanism of friction mechanism depends primarily on the roughness geometry of the harder
material, which represents the mean asperity slope.
Friction Response: Smooth Surface
Adhesion component of friction increases as plasticity index decreases.
Effect of Texture Direction on additive activation
The higher asperity deformation allows for the removal of surface oxides.
Oxide free surfaces, as stated before, have been indicated as a requirement to the reaction by which
MoDTC forms MoS2.
11. Conclusion
For very low specific film thickness values(Λ⪡1) and high plasticity index (ψ⪢1)(rough surface),
the friction values depend on the harder body.
Formation of MoS2 films were shown to be dependent on the sliding direction of anisotropic
surfaces; resulting in friction reduction of E 100%.
Aged oils showed COF values similar to those obtained with base oil. This behavior is attributed
to MoDTC depletion or oxidation.
Gasoline contaminated oils were more oxidized than the ones contaminated with ethanol.
Scope
• There is no evidence of high copper and lower Fe and Al in 5W30E22.
• Reason for formation of MoS2.
• Hematite and Magnetite are found in 5W30E100 and Base oil.
• What is the effect of texture on MoS2 formation.
12. Reference
Tiago Cousseau, Amilton Sinatora, Brazil ” Tribological response of
fresh and used engine oils: The effect of surface texturing, roughness
and fuel type” ,Tribology International, Volume 2016 (60–69).