Amartya Ku Das 118CR0674

1. Influence of RH and temperature in COF and wear
CR4102- Tribology of Materials
TA- Assignment
Submitted By – Amartya Kumar Das
Roll – 118CR0674
Course Instructor – Prof Debasish Sarkar
Department of Ceramic Engineering
National Institute of Technology, Rourkela

2. Contents
1. Introduction
2. COF and Wear
3. Effect of Temperature on COF
4. Effect of Temperature on Wear
5. Effect of Humidity on COF and Wear
6. Effect of Humidity on COF and wear of different materials
7. Reference

3. Introduction
In this assignment we will be studying about two main tribological
properties that is Co-efficient of Friction (COF) and Wear. Tribology is
the study of the science and technology of interacting surfaces in
relative motion, including friction, wear, lubrication, and related design
factors. And we understand how temperature and humidity affect COF
and Wear.

4. COF and Wear
• By definition, friction is the resistance to motion. The material, geometries, and
surface features of the bodies in contact, as well as the operating conditions and
environment, all influence the degree of this resistance. The ratio of the highest
friction force prior to relative motion to the normal load is known as the static
coefficient of friction.
• Wear refers to the loss of materials as a result of sliding. Wear is often
undesirable since it can result in increased friction and, eventually, component
failure. Wear is often reduced by employing a lubricant to separate the two
bodies so that they do not come into direct contact.

5. Effect of Temperature on COF
• With changes in temperature, the friction coefficient of some materials
may increase or decrease noticeably.
• In come materials with rise in temperature the friction coefficient rises ,
though not in a constant rate.
• While in some materials when we increase the friction coefficient shows a
increase and decrease pattern.
• This phenomena was checked by the Temperature rising experiment.
• To verify the effects of temp. on COF two specimens are taken, those are
PC film and Aluminium foil complex.
• The results of this experiment shows how temperature affects COF.
Reference - Material Friction Coefficient and Temperature, labthink instruments co. ltd,(China)

6. Effect of Temperature on COF (contd.)

7. Effect of Temperature on Wear
• Wear is affected by both Load and Temperature.
• Usually a higher temperature leads to a higher wear and lower
temperature leads to lower wear at constant load.
• Wear is highest at higher temperatures and high loads.
• However at very high temperature the chances of error in calculation
increases significantly.
Reference -Investigation of the Effect of Temperature on the Wear Rate and Airborne Noise in Sliding Wear (Kevin Lontin *, Muhammad Khan
and Bander Alharbi)

8. Effect of Humidity on COF and Wear
• The effect of Humidity varies on different materials. There is no one
mechanism to define how relative humidity (RH) will affect a material.
• Studying various Materials we can see how RH affects different
materials differently.
• To understand how it affects materials we study how RH affects few
materials

9. Effect of Humidity on COF and wear of different
materials
1. Effect of Humidity on Advanced Ceramics -
In advanced ceramics it was found that worn surfaces in low humidity
conditions is rough, but it is relatively smoother in higher humidity conditions
due to tribochemical reactions involving the adsorbed water molecules.
2. Effect of Humidity on silicon and silicon oxides –
The water adsorption behaviours of hydrogen-terminated Si-H surface and
native oxide (SiOx) surface are drastically different. The former is hydrophobic
while the latter is hydrophilic. And this leads to inconsistent behaviour towards
humidity.

10. Effect of Humidity on COF and wear of different
materials (contd.)
3. Effect of Humidity on Metals
In metals Although COF did not show a strong humidity
dependence, wear increased drastically when humidity was below
15%.
Hence from the above three examples we understand that RH shows
different behaviour towards different materials.
Reference - Effect of Humidity on Friction and Wear—A Critical Review (Zhe Chen , Xin He , Chen Xiao and Seong H. Kim)

11. Reference
1. http://en.labthink.com/en-us/literatures/material-friction-coefficient-and-temperature.html
2. https://www.mdpi.com/1996-1944/15/3/812/pdf
3. https://www.researchgate.net/publication/327162741_Effect_of_Humidity_on_Friction_and_Wear-
A_Critical_Review