What Are Graphitized Carbon Nanotubes?

Graphitized multi-walled carbon nanotubes are produced by annealing standard MWCNT powders under inert atmosphere (argon or nitrogen) at 2,400-2,800C for approximately 20 hours. This high-temperature treatment eliminates structural defects in the graphene lattice — sp3 carbon bonds, vacancies, and amorphous carbon deposits — transforming defective walls into near-perfect graphitic structure. The result is the highest crystallographic order achievable in a carbon nanotube, with electrical conductivity approaching graphite and ignition temperatures in air reaching 800C.

How Graphitization Changes MWCNT Properties

Property	Standard MWCNTs	Graphitized MWCNTs
Raman D/G Ratio	0.8-1.2 (high defect)	0.1-0.3 (low defect)
Electrical Conductivity	10^3-10^5 S/m	10^5-10^7 S/m
Ignition Temperature (air)	400-600C	750-800C
Interlayer Spacing	0.342-0.348 nm	0.335-0.338 nm (approaching graphite)
Thermal Conductivity (axial)	~1,500 W/m·K	Up to 3,000 W/m·K
Catalyst Residue	1-10%	<1% (burned off during annealing)

The key tradeoff: graphitization reduces BET surface area (defect sites close, inner pores seal) from 200-400 m2/g to 100-250 m2/g. For applications requiring maximum conductivity, oxidation resistance, or crystallographic perfection, graphitized MWCNTs are clearly superior. For applications depending on high surface area, standard MWCNTs may be preferred.

Applications of Graphitized Carbon Nanotubes

High-Conductivity Polymer Composites

Graphitized MWCNTs provide 10-100x lower percolation threshold compared to standard MWCNTs, due to higher intrinsic conductivity. At 0.5-2 wt% loading in thermoplastics or epoxy resins, graphitized MWCNTs achieve composite conductivities of 10-100 S/m — sufficient for ESD protection, EMI shielding, and through-thickness heating. This is the dominant commercial application.

Thermal Interface Materials

The near-perfect graphitic lattice gives graphitized MWCNTs axial thermal conductivities approaching 3,000 W/m·K — the theoretical maximum. In thermal interface materials (TIMs) for CPUs, power electronics, and LED assemblies, graphitized MWCNTs outperform standard MWCNTs at equivalent loading. Vertically aligned arrays are particularly effective.

High-Temperature Applications

Graphitized MWCNTs are the only CNT grade suitable for prolonged air exposure above 500C. Their oxidation onset at 750-800C — 200C higher than standard MWCNTs — makes composites viable for brake components, aerospace thermal protection, and high-temperature filtration where conventional MWCNTs would oxidize.

Electrochemical Applications

For batteries, supercapacitors, fuel cells, and electrocatalysis, graphitized MWCNTs serve as superior conductive supports. Reduced defect density minimizes parasitic redox reactions from sp3 carbon sites, improving Coulombic efficiency and cycle life in Li-ion battery cathodes over 500+ cycles.

Tribological Coatings

The near-frictionless graphitic surface makes graphitized MWCNTs exceptional solid lubricant additives. In polymer coatings and metallic lubricant formulations, graphitized CNTs reduce wear rates by 30-50% vs. standard MWCNTs. Reduced surface reactivity also improves chemical compatibility in harsh environments.

Selecting a Grade

Available in outer diameters from 8-15 nm to >50 nm, and in COOH/OH functionalized grades. Smaller diameters offer higher aspect ratio; larger diameters are easier to disperse. Cheap Tubes provides TGA and Raman data on request to confirm crystallographic quality. Pricing starts at $2.80/g. Contact us for volume pricing and lot-specific characterization data.