1. Tribological performance of Cu/CNTTribological performance of Cu/CNT
composites fabricated by Powdercomposites fabricated by Powder
Metallurgical TechniqueMetallurgical Technique
Guide: Asst. Prof. Vishwanath KotiGuide: Asst. Prof. Vishwanath Koti
1. Aggarwal Rohil (1MS12ME016)
2. Ashutosh Singh (1MS12ME033)
3. Karthik Ganeshan (1MS12ME064)
4. Kashyap Balasubramanian (1MS12ME066)

2. Motivation
There is a need for an enhanced material because of
the following short comings:
● High friction coefficient of slidding brushes used in
electric motors.
● Low thermal expansion coefficient of the lighter
materials like aluminium.
● Low electrical and thermal conductance of high
strength Material.

3. Literature Survey
With the rising demands of low weight- high strength materials the need of composite
was figured out which lead to various studies on the same. With the introduction of
CNTs in 1991 the study of composite materials took paradigm turn which resulted
many studies on CNT Composites.
Many studies have been done on Metal Matrix CNT composites that shows
enhancements of the mechanical and tribological properties. Metal Matrix that
attracted most of the searcher is Aluminium and copper.
In the studies researcher have fond out that the properties of the composites are
greatly affected by the manufacturing method carried out for the production of the
same.
Tu et al. (2001) [1] have fabricated Cu/CNT composites through powder metallurgy
technique and have shown that hardness increases with the addition of CNTs . He also
showed that tribological properties of the materials can also be enhanced with the
addition of CNT which reduces COF. Daoush et al. (2010) [2] have reported that yield
strength of the composite increases up to 342.2 MPa for which is 2.85 times higher
than the unreinforced.

4. ● In on the of study by Chai et al. (2008) [3], it has been shown that yield strength and ultimate
strength Cu/CNT can be as high as 420 MPa and 710 MPa respectively by following electro-
deposition method of fabrication.
● In a study by Chai and Chen [4], they have shown a significant improvement in thermal
conductivity (604 Wm-1K-1) of Cu/CNT composites processed by electrochemical deposition
which is 1.5 times that of pure Cu.
● Conclusion:-
● All the literatures have shown a converging results which say that most of the properties can
be enhanced by the addition of CNTs.
● However the studies have given clear evidences that there is a critical vol% of CNTs that could
be added in the matrix and beyond this limit CNTs don’t help in enhancement.
● The studies suggest that the dispersion of CNTs in the metal matrix is very crucial and it
posses a serious issue.
● There is no available literature on Corrosive properties to best of our knowledge.
● The most common method used for fabrication is Powder Metallurgy technique.
● The most efficient method that has shown impressing results is electro-depositing method.
● The problem of porosity in the composites fabricated by powder metallurgy can be overcome
by secondary mechanical process like rolling and extrusion.

5. Potential Applications of Copper
1. Bearings
Copper bearings possess better wear resistant properties when compared
to standard steel bearings. Also Cu possess higher heat dissipation
capabilities than steel or cast iron.
2. Electrical Brushes
High electrical conductivity along with better heat dissipation and
enhanced wear resistant properties makes Cu an ideal choice for bushes.
3. Brakes
Copper makes for a smooth braking experience, transfers heat efficiently
and has high wear resistant properties. Cu also helps brakes' effectiveness
in cold weather.
Thermal conductivity: Cu: 385 W/mK Steel:50.2 W/mK
Electrical Conductivity: Cu: 58.5*10.E6 Siemens/m Steel:10.1*10.E6

6. Use of Cu/CNT
1. Bearings
Adding CNTs to Copper makes the base matrix harder and stronger as strength of the
reinforced matrix becomes comparable to that of steel, thermal conductivity does not
increase however.
2. Electrical Brushes
CNT reinforced Cu enhances the electrical conductivity of the material which is
beneficial for electrical systems like brush. Also the strength of the brushes increases
which can help in making thinner and light weight sections.
3. Brakes
Increased wear resistant properties are observed when CNTs reinforce Copper. This
increases the life of brakes thereby reducing maintenance costs of vehicles. Also
enhanced in thermal conductivity of Cu will help keep the brakes cooler even after
prolonged use and would not decrease it’s effectiveness.

7. Process Plan
● Electroless Plating: Ni coating of CNTs
Activated CNTs using SnCl2 – HCl solution for 30
min are coated using the electroless bath of Ni
Solution for more than 1 hour.
Electroless Bath compositionPlating mechanism

8. ● With Copper powder and Coated CNTs, the composite
would be fabricated via Powder Metallurgical technique
● Ball Milling: The Cu/CNT powders, dispersed in acetone
or an organic liquid, are mixed in a Planetary Ball Mill
for different time durations starting from 30 min.
● Sintering: the Green Compact obtained after ball
milling is sintered at 700 0C for better diffusion of
components
● Extrusion: the 20mm dia sintered billet is extruded to 9
mm dia components by hot extrusion and/or cold
extrusion, maintaining a Extrusion Ratio of 2.25 (2.22)

9. Testing Parameters
● Hardness
● Wear Rate
● Porosity
● Compression

10. Expected Results
The governing equation for the determination of wear rate in a
steady state condition is used to examine the effect of porosity,
hardness.
g1-function of applied load
g3-function of particle diameter d
fv-volume fraction
L-Sliding distance
K-Wear coefficient

11. References
1) Tu, J. P. Yang, Y. Z. Wang, L. Y. Ma, X. C. and Zhang, X. B. (2001) ‘Tribological
properties of carbon-nanotube-reinforced copper composites’, Tribology
Letters, Vol. 10 No.4, pp.225 – 228.
2) Daoush, W. M. Lim, B. K. Mo, C. B. Nam, D. H. and Hong, S. H. (2009) ‘Electrical and
mechanical properties of carbon nanotube reinforced copper nanocomposites
fabricated by electroless deposition process’, Materials Science and Engineering:
A, Vol. 513, pp.247 – 253
3) Chai, G. Sun, Y. and Chen, Q. (2008) ‘Mechanical properties of carbon nanotube–
copper nanocomposites’, Journal of Micromechanics and Microengineering, Vol. 18
No.3, 035013.
4) Chai, G. and Chen, Q. (2010) ‘Characterization study of the thermal conductivity of
carbon nanotube copper nanocomposites’, Journal of composite materials. Chai, G.
and Chen, Q. (2010) ‘Characterization study of the thermal conductivity of carbon
nanotube copper

12. THANK YOUTHANK YOU