CNT & CNTs NANOCOMPOSITESFABRICATION

BY: UDAY PRADHANREG.NO:2014129002

DEPTT:CMSNT(MTECH)

Carbon nano tube• CNTs are allotropes of carbon with a cylindrical

nanostructure.• Nanotubes have been constructed with L/D ratio of

up to 132,000,000:1• The walls formed by one-atom-thick sheets of carbon,

called Graphene.• These sheets are rolled at specific and discrete ("

chiral") angles, • The combination of the rolling angle and radius

decides the nanotube properties (metal or semiconductor)

From the picture,

-SinƟ = (h/n a1)-Sin(180-120-θ)-Sin(60-θ)=sin60.cos θ-cos60.sin θ-n sinƟ = (h/a1) .............. (i)

-[(3^.5/2)cosƟ+(1/2)sinƟ ..... (ii)

We have a1 =a2= (3)^.5*dccdcc=bond length

From equation (i) & (ii) we equate both

(n/m)sinƟ = {(3^.5)/2}cosƟ-(1/2)sinƟ

[(n/m)+(1/2)] sinƟ = {(3^.5)/2}cosƟ

{(2n+m)/2m}sinƟ = {(3^.5)/2}cosƟ

tanƟ = m{(3^.5)/2}/(2n+m)

a1a2

x

y

(0,0) (1,0) (2,0) (3,0)

(1,1) (2,1)

Zigzag

Armchair

(2,2)

(4,0) (5,0) (6,0)

(3,1) (4,1) (5,1)

(3,2) (4,2) (5,2)

(7,0) (8,0) (9,0)

(6,1) (7,1) (8,1)

(6,2) (7,2) (8,2)

(10,0) (11,0)

(9,1) (10,1)

(9,2) (10,2)

(3,3) (4,3) (5,3) (6,3) (7,3) (8,3) (9,3)

(4,4) (5,4) (6,4) (7,4) (8,4) (9,4)

(5,5) (6,5) (7,5) (8,5)

(6,6) (7,6) (8,6)

(7,7)

a1a2

x

ya1

a2x

y

(0,0) (1,0) (2,0) (3,0)

(1,1) (2,1)

Zigzag

Armchair

(2,2)

(4,0) (5,0) (6,0)

(3,1) (4,1) (5,1)

(3,2) (4,2) (5,2)

(7,0) (8,0) (9,0)

(6,1) (7,1) (8,1)

(6,2) (7,2) (8,2)

(10,0) (11,0)

(9,1) (10,1)

(9,2) (10,2)

(3,3) (4,3) (5,3) (6,3) (7,3) (8,3) (9,3)

(4,4) (5,4) (6,4) (7,4) (8,4) (9,4)

(5,5) (6,5) (7,5) (8,5)

(6,6) (7,6) (8,6)

(7,7)

Armchair geometry shows metallic behavior

Zig-zag geometry shows semiconducting behavior

The conductivity of chiral CNT’s varies depending on the chirality

A CNTs can be viewed as a rolled Graphene sheet along its circumferential direction, is determined by its chiral vector (Ch)

The chiral vector is defined as Ch = na1 + ma2.

• tan Ɵ = m{(3^.5)/2}/(2n+m) { here Ɵ= chiral angle} • If the chiral angle is 0°,m=0 CNTs is classified as zig-zag• If the chiral angle is 30°, m=n, CNTs classified as armchair• All other angles between 0° and 30° are referred to as chiral

nanotubes.

STM can determine the chirality of the structure and STM, AFM can determine the diameter

Armchair arrangement of carbon atomsZig-zag arrangement of carbon atoms

Chiral arrangement of carbon atoms

CNTs/ METAL MATRIX COMPOSITE

MWCNTs(passivated by elastomer)

Aluminum powder

mixing by hot press

353 K

CNT/AL MATRIX COMPOSITE

• The process comprises two steps: 1) A precursor in which CNTs were uniformly

dispersed in an elastomer (natural rubber and ethylene-propylene rubber) matrix was prepared;

• The elastomer matrix was displaced by Ala)EPDM matrix b) NR matrix

MOLECULAR LEVEL MIXING PROCESSThis process enables CNTs to be mixed and react

with ions of inorganic matrix in molecular level overcoming agglomeration

Mixing of CNTs and matrix material done in solution instead of conventional powder mixing

Homogeneous mixing distribution of CNTs and high interfacial strength between CNT and inorganic matrix obtained

STEPS OF FABRICATION

MOLECULAR LEVEL MIXING

CNTs passivated by functional group

A soluble salt containing matrix ion

Mixing

CNT/Metal Nanocomposite

DISINTEGRATED MELT DEPOSITION (DMD) METHOD

• To fabricate the Mg nanocomposites containing 0.3, 1.3, 1.6 and 2 weight percentage of carbon nanotubes (CNTs) respectively

• Matrix :Elemental magnesium of >99.9% purity• Reinforcement : CNTs• Involved heating Mg and CNTs placed in alternate

layers to 750°C under Ar gas atmosphere.

Impeller coated with ZIRTEX 25 (86% ZrO2, 8.8% Y2O3, 3.6% SiO2, 1.2% K2O and Na2O and 0.3% trace inorganics) to avoid iron contamination to the molten metal.

Fabrication process

(DMD) METHOD

Magnesium>99.99% purity CNTs

AT 720 C, Ar gas

Stirred by impeller at 450 rpm for 5 min

Cooled in metallic mould

Mg /CNTnanocomposite

Electroless plating processCNTs/Ni-P nanocomposites

• Electroless plating method can deposit many metals on almost any substrates regardless of size &shape

• Functionalization of CNTs : oxidized by 0.38M potassium bichromate and 4.5M sulfuric acid at 60 ℃for 30 min

• Electroless plating solution: nickel sulfate(15 kg/m3), sodium hypophosphite(16 kg/m3), lactic acid(8 kg/m3), sodium acetate(10 kg/m3), potassium antimony tartrate(0.001 kg/m3) & 0.005 kg/m3 surfactant (cetyltrimethylamine bromide)

• Condition: 85±1 and 4.67±0.1(pH) for 2hrs℃

ELECTROLESS PLATING PROCESS

CNTs ultrasonically dispersed

Functionalization of CNTs

CNTs/SiC MATRIX NANOCOMPOSITES

FUNCTIONALIZATION OF THE CNTS 10%wt

SiC nanoparticles

Hot pressing2272k

CNTs/SiC MATRIX NANOCOMPOSITES