Synthesis & Characterisation of CNT reinforced Al Nanocomposite
• By: Malik Tayyab with co-member Muhammad Mutahir.This work was conducted as a part of my final year project at NED University of Engineering & Technology during the year 2011 in Karachi, Pakistan.This is a pdf file; since i created the presentation in ppt format(which is obiviously animated) therefore some things you might consider unclear. If you would like to have the ppt file or any other suggestion regarding this topic you can reach me through my email address: firstname.lastname@example.org
Group 2MM 07009 Muhammad MutahirMM07026 Malik TayyabProject Advisor Prof. Dr. Ashraf AliCo-Project Advisor Asst. Prof. M. Sajid Ali Asghar Department of Materials Engineering, NED University of Engineering & Technology.
A nanometer is one billionth of a meter.Nanotechnology is the study of manipulating matter onan atomic and molecular scale.Materials or structures possessing at least one dimensionsized from 1 to 100 nanometers.Currently undergoing extensive development.It has not yet yielded significantly useful commercialproducts. Malik Tayyab Material Engineer
1. Data Storage Devices.2. Sensor units.3. Optical devices.4. Biomedical products.5. Computing and information storage devices.6. Smart materials using Nano- scale devices. Malik Tayyab Material Engineer
Smallest synthetic motor thats ever been made. A gold rotor, nanotube anchors and opposing stators are simultaneously patterned around the nanotubes using electron beam lithography. Malik Tayyab Material Engineer
Bottom-up: Top-down:Products are manufactured one Every product begins with aatomic particle at a time. bulk material process and is subsequently refined down.Seek to have smaller (usually Top-down approaches seek tomolecular) components built up create Nano scale devices byinto more complex assemblies. using larger, externally controlled ones to direct their assembly. Malik Tayyab Material Engineer
Bottom Up Approach refers to the build up of amaterial from the bottom: Atom by Atom, Molecule byMolecule, or cluster –by-clustere.g. Polymer Synthesis Malik Tayyab Material Engineer
i. Zero-Dimensional Nanostructures: Nanoparticles ii. One-Dimensional Nanostructures: Nanowires and Nano rods iii. Two-Dimensional Nanostructures: Thin Films iv. Three-Dimensional Nanostructures: Special Hybrid Structures • Nano Buds • Nano Torus Malik Tayyab Malik TayyabMaterial Engineer
• Structural components with high strength to weight ratios• Batteries with better power output• Abrasion resistant coatings• Automotive Parts Ball bearings made of CNT-Cu Nano composite. Bicycle Crank set made of CNT-Al Nano composite. Malik Tayyab Material Engineer
• Nano composites differ from conventional composite materials due to the exceptionally high surface to volume ratio of the reinforcing phase.• Nano materials may have a significantly lower melting point or phase transition temperature.• Gravity plays no role whatsoever and inertial effects are basically nonexistent because things are just so small. All these and other similar factors give nanomaterials unique properties like: Copper turns transparent from opaque. Gold becomes catalytic. Aluminium becomes combustible. Malik Tayyab Material Engineer
There are two main types of carbon nanotubes thatcan have high structural perfection.• Single-walled nanotubes (SWNTs) consist of a single graphite sheet seamlessly wrapped into a cylindrical tube.• Multi-walled nanotubes (MWNTs) comprise an array of such nanotubes that are concentrically nested like rings of a tree trunk. Arm chair or Metallic Zig Zag Chiral Malik Tayyab Material Engineer
Two techniques selected for production ofNano tubes:• Arc Discharge Process• Flame SynthesisCan be used for the productionof both SWNTs and MWNTs. Malik Tayyab Material Engineer
The most common and perhaps easiest way to produce CNTs. A technique that produces a complex mixture of components, andrequires further purification - to separate the CNTs from the soot andthe residual catalytic metals present in the crude product. Applicable for production of both SWCNTs and MWCNTs. Pressure gauge Gas out Gas in Feed stock cathode Water in Water out Malik TayyabMaterial Engineer Anode
Sonication is the act of applying sound energy toagitate particles in a sample.• Temperature• Solvent(normally ethanol)• Vibrations• Operating time Malik Tayyab Material Engineer
CNTs produced by arc discharge at magnification 6000X. Malik Tayyab CNTs produced by arc discharge at Material Engineer magnification 24000X
Flame SynthesisA wall-stagnation flow burner and its wall was made of catalystmaterial.The reactant gas used for the formation of the flame and thesynthesis of CNTs was ethylene/air premixed gas. Malik Tayyab Malik Tayyab Material Engineer
Source Material Purity Level Mean Diameter F.S. Corp. Aluminum Powder 99.9% 2.7 30 µm Arc Discharge CNT >50-70% 1.95 N/AShenzhen Nanotech CNT >97% 2.1 30 - 40 nm MWNTs were used in this study with diameter 30 nm-40 nm. Malik Tayyab Material Engineer
SEM images of CVD synthesized CNTs (source: (a) Shenzhen Nanotech ) (b) MMD SEM Analysis Malik TayyabMaterial Engineer
SEM images of Aluminium powder at different magnifications. Malik Tayyab Material Engineer
µmHistogram showing the particle size distribution of Aluminium powder. Malik Tayyab Material Engineer
• Laser Particle Size Analysis depends upon analysis of the "halo" of diffracted light produced when a laser beam passes through a dispersion of particles in air or in a liquid.• The angle of diffraction increases as particle size decreases, so that this method is particularly good for measuring sizes between 0.1 and 3,000 μm. Analysis indicated that Aluminium powder has a wide particle size distribution ranging from 10 μm– 200 μm, with average particle size around 30 μm. Malik Tayyab Material Engineer
The following challenges must be met:1. Overcome the huge surface energy, enormous surface area or large surface to volume ratio.2. Ensure all Nano materials with desired size, and provide uniform distribution.3. Interfacial bond strength between CNT and metal matrix.4. Chemical and structural stability of CNTs. Malik Tayyab Material Engineer
Malik Tayyab Material EngineerThis is my owninterpretation; Ihaven’t foundthis in anyresource. Illustration of dislocation interaction in a particulate composite (or age hardened alloy) and carbon nanotube reinforced metal matrix composite.
Malik Tayyab Material EngineerProcessing routes for CNT-MM Nano composites.
• Powder Metallurgy is the most popular & widely applied technique.• Electro deposition & Electro less deposition are the second most important technique for deposition of thin coatings. Malik Tayyab Material Engineer
Basic process steps consist of mixing CNTs with metalpowder by grinding or mechanical alloying, Followed byconsolidation by compaction and sintering. Malik Tayyab Material Engineer
Malik Tayyab Material Engineer CNTs Ultra sonication of CNTs in ethanol for 1 hour. Disentangled CNTs CNT-Al Powder Aluminium Ball Milling Powder Compaction Sintering CNT-Al Nano compositeProcess flow diagram for CNT-Al Nano composite.
Plastic Coupling Agent (PCA, an organic solvent: e.g. ethanol) isadded to vial to avoid excessive welding and straining of theparticles. Malik Tayyab Material Engineer
Ball Mill Vial with Steel Balls(a) Schematic representation of ball mill vialshowing the impact of milling media on powderparticles (b) Ball-powder-ball impact. Malik Tayyab Material Engineer
During milling Al-CNT powder, following set of events occur :-• Particle Deformation or Flattening,• Sandwiching• Particle Welding,• Fracturing causing grain size reduction. Malik Tayyab Malik Tayyab Material Engineer
1 % CNT, 200 RPM, 3 hours2% CNT, 200 RPM, 3 hours5% CNT, 200 RPM, 3 hours Sample # % Composition Weight of CNT/g Weight of Al/g 1 Pure Al - 5 2 1%CNT-Al 0.05 4.95 3 2%CNT-Al 0.10 4.90 4 5%CNT-Al 0.25 4.75 Malik Tayyab Material Engineer
Powder handling was performed in Vacuum Glove Box, Argongas was supplied for inert atmosphere.In order to avoid environmental effects like oxidation ofAluminium powder, moisture adsorption.Aluminium powder is highly reactive, Resources indicate that athin passivation layer of alumina (4 nm thickness) forms in about100 picoseconds on any exposed aluminium surface(AluminiumNano clusters). Malik Tayyab Vacuum Glove Box. Material Engineer
Milled powder samples were compacted by a 100 TonHydraulic press.Compaction pressures were calculated and determinedby trail and error method.In Accordance to ASTM Green density vs. CompactionPressure plot for 601AB Aluminium, 40 M Pa appearedto be the optimum pressure. Malik Tayyab Material Engineer
• Process based on Atomic Diffusion.• Driving force for densification is the change in free energy from the decrease in surface area. Solid state sintering Liquid phase sintering Temperature (°C) 540 °C 0.5 hour Time (hours) Malik Tayyab Material Engineer
Characterisation Technique• Scanning Electron Microscopy• X Ray DiffractionThe dispersion of CNTs in Aluminium matrix was investigated.CNTs were observed at the weld interfaces between Aluminiumparticles. Malik Tayyab Material Engineer
2% CNT-Al Nano composite showing weldsplats of fine Al particles on coarse ones. Malik Tayyab Uniform distribution of CNTs found in the Al Material Engineer matrix.
Figure showing 2% CNT-Al Nano composite showing CNT reinforcement in Al matrix. Malik Tayyab Material Engineer
A perfect view of CNT at the weld interface in 2% CNT-Al Nano composite. Malik Tayyab Agglomerates of CNTs in 5% CNT-Al Nano Material Engineer composite.
CNTs AluminiumIndividual X-Ray diffratograms of CNTs (100% intensity at 26°) and Aluminium Malik Tayyab overlapped. Material Engineer
X-Ray diffraction pattern of 2% CNT-Al Nano composite, no carbon peak observed. Malik Tayyab Material Engineer
• Improper powder handling.• Oxygen pick up by Aluminium powder during processing.• Improper calculation of the plastic coupling agent (PCA). One of the failed sintered compacts. Fractured surface of failed Nano CNTs observed at the fractured surface. composite compact.
Elements Weight % Atomic % CK 13.12 25.33 Al K 86.88 74.67 Totals 100.0Energy Dispersive Spectroscopy confirming the presence of CNTs in Malik Tayyab the 2% CNT-Al Nano composite (Elemental Detection). Material Engineer
Malik Tayyab Material EngineerElements Weight % Atomic % OK 5.67 9.21 Al K 94.33 90.79 Totals 100.00 EDS pattern showing no carbon peaks, Oxides were observed in the matrix.
Malik Tayyab Material Engineer SEM SecondaryMapping Image SEM X Ray ElectronTime provided was not sufficient due to some constraints elsethe nanofiber like image had appeared in the C x-ray map. X-Ray Mapping Images showing the distribution of CNTs in aluminium matrix of 2% CNT-Al Nano composite along with oxide dispersions.
• Ball milling has been proven to be a very promising technique for the dispersion of CNTs in Al matrix. It has also been noticed that this technique excessively strain hardens the matrix as the milling time increases.• CNTs were found to be embedded in the matrix as an interphase at the Aluminium powder particle weld interfaces.• The fractured green compact also revealed CNTs in between the Aluminium crystallites.Future Work and Recommendations• CNT-Al can also be prepared via Electrodeposition; this process gives added benefit for coating surfaces requiring wear resistance.• Pure Al and Aluminium alloys are known to generate hydrogen from alkaline water for Polymer Electrolyte Membrane Fuel Cells. CNT-Al nanocomposites can be used for hydrogen generation as a green renewable energy source.• Hybrid Nano composite comprising of two different Nano reinforcements might be another interesting approach to enhance the mechanical and other physical characteristics of the nanocomposites (CNT/ Dispersed Oxides/ Al Composite or using two different types of CNTs). Malik Tayyab Material Engineer