aluminum wetting of carbon nano-tubes...aluminum wetting of carbon nano-tubes ayman ahmed, nathan...
TRANSCRIPT
Carbon Nanotubes (CNTs) are known for their extraordinary strength and efficiency in heat conduction. In fact, CNTs are the stiffest and strongest known fibers to man. The high surface area and the perfect architecture of these CNTs are responsible for their amazing qualities. The ease of growth of these CNTs has led to some advanced research in this field. This project deals with infusing the great qualities of the CNTs into a very versatile metal such as aluminum. Aluminum is lighter than steel but lacks the rigidity of iron. Proper wetting of aluminum into CNTs would lead to a nano-composite which is extremely tough, durable and highly heat conductive. Hence, we look at the potential wetting properties of CNT forests decorated with metal nano-particles produced through laser ablation. Copper and nickel nano-particles being two metals that were tested.
SETUP:
Aluminum Wetting of Carbon Nano-tubes
Ayman Ahmed, Nathan Hordy, Prof. Jean-Luc Meunier and Prof. Raynald Gauvin
EXPERIMENTAL PROCEDURE:
Substrate Cleaning 20 min with acetone
in ultrasonic bath
Heating Heat to 700° C
for 30 min in Argon
C2H2 Injection 4 min C2H2 injection (45 sccm) at 700° C
Al melting on CNT
700/750/800° C for 0/15/30/60 mins
Laser Ablation Decoration with Cu or Ni nano-particles
CNT Growth 30 min growth
at 700° C in Argon
CONCLUSION: High quality CNTs can be created on Stainless Steel 316 at 700° C with 4 mins of C2H2 injection and 30 mins
growth time. Cu and Ni coating on the CNTs does not make a difference in terms of Al wettability. Al foil (97% Al) on CNT does not readily melt at its M.P. of 660.4° C due to the CNTs acting as a superb heat sink. At least 15 mins at 750° C is required for the proper melting process. Although Al foil falls off the CNTs, under SEM small clumps of Al are seen stuck onto the CNTs. EDS analysis reveals that these are primarily Aluminum oxide. These clumps reduce drastically in amount on 30 min of heating at 750°C and beyond. Further analysis needs to be done to see if a contact angle can be measured from the clumps to calculate wettability and also to observe the Al/CNT interface through electron microscopy. Denser metallic nano-particle decoration or full metallic coating around each CNT from PVD can also be possible alternatives. Special thanks to Mark McArthur
RESULTS: CNTs survive even at high temperatures like
800° C and heating for 60 mins
Al foil (small circles) always sticks to the SS 316 (big silver circles) after heating but it always falls off from the CNTs (big black circles). The
heating causes the Al foil to shrink up and wrinkle
After heating
Although Al foil falls off, under the SEM, small clumps are seen at random places
Using Energy-dispersive X-ray spectroscopy (EDS) these clumps are found to be Al and O being present in almost 1:1 ratio, suggesting there is a pure Al core surrounded by Al2O3
POTENTIAL APPLICATIONS:
• Al based engine blocks
• Light car chassis
• Strong plane bodies
• More durable submarines
• Aerospace technology
• Power transmissions
cables
• Excellent radiators and
heat sinks
• Efficient cooling fins for
electronics
• Brushes for commercial
electric motors
• Robust weapons
• Body armour
• Sports equipment
• Alternative to steel/iron
...to name a few