The document summarizes research on the friction and wear of metals under micro-abrasion and dry/wet sliding conditions. It includes an introduction describing the research objectives to characterize coefficient of friction (CoF) and wear rates of metals under different wear modes. The experimental procedure used a micro-abrasion tester to apply loads to metal samples in contact with a rotating steel ball under various conditions to produce different wear modes. Results found that pure rolling abrasion generated the highest wear rates while dry sliding abrasion produced the lowest wear rates and CoFs. The research concluded the tester was useful for evaluating CoF under different tribological pairs and conditions.

1. LOGO
Friction and wear of metals
under micro-abrasion, wet and
dry sliding conditions
Presented by,
MUZAMMIL HUSSAIN
2020280028

2.  Introduction
 Basic Knowledge
 Basic Terms
 Micro Abrasion Wear Test
 Literature Review
 Experimental Procedure
 Materials & Sample Preparation
 Results & Discussion
 CoF & Wear Rolling Abrasion
 CoF & Wear Under Dry Sliding
 Special Case
 Summary
 Conclusion
 References

3. Basic Knowledge
What is Wear?
Wear is the damaging, gradual removal or deformation of material at
solid surfaces. Causes of wear can be mechanical (e.g., erosion) or
chemical (e.g., corrosion). The study of wear and related processes is
referred to as tribology.
Types of Wear
I. Adhesive wear
II. Abrasive wear
III. Surface fatigue
IV. Fretting wear
V. Erosive wear
VI. Corrosion and oxidation wear

4. Basic Terms
What is Friction?
Friction is the force resisting the relative motion of solid surfaces, fluid
layers, and material elements sliding against each other.
Types of Friction
I. Dry Friction
II. Fluid Friction
III. Lubricated Friction
IV. Skin Friction
V. Internal Friction
Higher CoF: Rubber/ Eraser
Lower CoF: Ice Cube

5. Micro Abrasion Wear Test
INTRODUCTION
This method is used for characterization and evaluation of wear rate and
resistance of wide range of materials under rolling abrasion mechanism.
For Example:
 Metals
Ceramics
Polymers
Thin coatings
Aim: Spherical or ellipsoid geometry ~ 25.4 mm in diameter.
Advantage:
 Formation of defined small wear scars (micro-scale) with rolling
abrasion patterns.
 Plowing or grooving features depending on some testing conditions.

6. Introduction
Research Objectives
 To characterize and compare CoF and wear rates of
some metallic materials under different wear modes
namely micro-abrasion (rolling abrasion & mixed rolling
abrasion/grooving), wet and dry sliding abrasion.
 Wear modes were achieved by conducting test under
muddy environment at different SiC particles conc.
 Wet and dry condition at three different loads using an
instrumented micro-abrasion tester.
 Wear volumes were measured and visualized wear
patterns.
 Wear modes have an effect on CoF and wear rate.

7. Introduction
Rolling Abrasion Plowing or grooving
It is produced by free hard micro-
particles rolling at the sliding interface
promoting commonly numerous micro-
indentations.
Wear feature:
Ductile or brittle behavior in the scar.
It is generated by the sharpness of
hard micro particles fixed at one
counter face sliding against the other.
Wear feature:
Formation of micro-grooves or
scratches inducing the mechanism of
micro-cutting, micro-plowing and
micro-cracking along the scar in the
sliding direction.

8. Literature Review
 Micro-Abrasion Wear Test
 It is introduced by Rutherford and Hutchings in 1996.
 It can be used for friction measurements and corrosion analysis.
 Gee and Wicks in 2000 measured tangential forces (friction force) of
some coatings. They found tester modification to be very effective to
evaluate CoF behavior of those coatings.
 In 2009, Cozza et al. (Ref 31) studied the influence of constant pressures
on the CoF of an AISI H10 steel in a micro-abrasion tester.
 Cozza et al. (Ref 32) investigated the effects of hardness on CoF and
wear rates for TiN and TiC coatings deposited in an AISI D2 steel.
 Peng et al. (Ref 34) used a modified microabrasion tester to evaluate
wear resistance and CoF behavior of a Mn16 steel in simulated iron ore
mill conditions.

9. Experimental Procedure
Materials & Sample Preparation
High ductility/low hardness
Medium ductility/ med hardness
Low ductility/ high hardness

10. Experimental Setup
4mm thickness were cut from 25.4 mm diameter bars of three different
materials.
25.4 mm diameter AISI 52100 Steel balls were used as counter face for all
tests.

11. Experiment
Basically, the test is to load a flat material specimen against a rotating steel ball with
predefined normal force, speed and cycles to produce sliding contact under specific
conditions. Either an abrasive slurry or water are dripped continuously onto the ball and
entrained into the contact interface by the ball rotary effect for the micro-abrasion or wet
conditions, respectively. In the tester, the steel ball sample is clamped between two coaxial
driving shafts rotated by an electric motor. The electric motor is controlled to rotate at
constant speed and specific ball cycles or testing time through an encoder with 0.75 of rotation
precision connected to a USB-6009 data acquisition (DAQ) device.
The load sensor is also connected to the USB-6009 data acquisition (DAQ) device and a
computer for monitoring and acquiring the tangential force generated by friction produced by
the steel ball sample that slides against the flat material sample.
Muddy conditions were conducted by using two slurries with different abrasive particles
concentrations to achieve pure rolling abrasion and rolling abrasion combined with grooving,
respectively.
CoF can be calculated as follows:
Ff is the friction force measured with load cell
N is the normal applied force

12. Results & Discussion!
CoF and Wear under Rolling Abrasion
The following figure shows the average values of CoF and wear rates obtained at 1, 2
and 3 N, and the CoF behaviors for 1 and 3 N for the materials tested under MHC
conditions.

13. Scanning Electron Microscope (SEM) Analysis
Results

14. Special Case
However, the scars generated in the AISI 6061-T6 presented substantial amounts
of embedded SiC particles at 3 N as identified by EDS analyses as shown in
following figure.
It is due to its low hardness promoting easier and deeper SiC indentations and embedment.
The CoF increase obtained for AISI 6061-T6 at 3 N was related to the large amount of SiC
particles embedment. Those embedded particles in the scar do not roll, but they abrade the
steel ball surface in some extent as an effect of two-body-abrasion mechanism generating
higher shear forces. All materials exhibited a wear rate increase with load which was
proportional in some cases.

15. MLC condition

16. Results
MLC conditions

17. CoF & Wear Under Dry Sliding

18. CoF & Wear Under Dry Sliding

19. Special case
The accumulation of debris can be identified at the superior region of a wear scar
contour of the AISI 6061-T6 by EDS analyses, as shown in Fig.

20. Summary
Considering that wear progression in the test samples promotes wear crater
depth increase, it is possible that load applied changes, in some extent, through
the test since the L-shaped arm tends to lose the initial position from the no-
wear initial condition. Measuring load applied dynamically in the micro-
abrasion tester would be valuable for getting deeper tribological analysis which
is subject of further research in our research group.

21. Conclusion
 This research presents that wear mode had an effect on wear rate and CoF
in metallic materials.
 Pure rolling abrasion generated the highest wear rates for all the materials
and loads tested.
 Mixed rolling abrasion/grooving produced higher CoFs, but lower wear
rates than those produced by pure rolling abrasion.
 Dry sliding abrasion generated grooving patterns for all materials and
loads. It also promoted the lowest CoFs and wear rates for all materials and
loads tested.
 The tester used was found to be very useful, practical and appropriated as
an efficient tool for CoF evaluation of different tribo-pairs and conditions.
Consistent reproduction of specific wear modes and good reproducibility
were achieved with relative ease.

22. References
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Resistance of Thermochemically Treated Steels in Aqueous Solutions: Mechanisms,
Maps, Materials Selection, Tribol. Int., 2008, 41, p 141–149
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Abrasion of Y-TZP in Tea, Wear, 2013, 297, p 713–721
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the Wear Resistance of Traditional Ceramic Materials by Means of Micro-Abrasion
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8. 8. M. Sampaio, M. Buciumeanu, B. Henriques, Filipe S. Silva, J.C.M. Souza, and J.R.
Gomes, Comparison Between PEEK and Ti6Al4V

23. THANKS FOR LISTENING