Page 23 - Handbook of Surface Improvement and Modification

18 Scratch and Mar Resistance

2.2.5 NANODIAMOND & DIAMOND-LIKE CARBON

GENERAL INFORMATION
Name: nanodiamond CAS #: 7782-40-3 EC #: 231-953-2
Active ingredient, wt%: 98-99.9
PHYSICAL PROPERTIES
State: powder Odor: none Color: white to light green
o
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Melting point, C: 3727 Specific surface area, m /g: 280-400
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Particle size, nm: 4-60 Density, kg/m : 3005-3500
HEALTH & SAFETY
o
Autoignition, C: 420 Rat oral LD50, mg/kg: 2000
ECOLOGICAL PROPERTIES
Aquatic toxicity, Daphnia magna, 96-h, LC50: >100
Biodegradation probability: not readily degradable
USE & PERFORMANCE
Outstanding properties: very high hardness, improvement of scratch resistance, chemical resis-
tance, biocompatibility
Recommended for polymers: acrylics
Recommended for products: clearcoat, biomedical application, sunscreens, fluorescent labels
Concentrations used, wt%: 0.5-1.5
Two types of nanodiamond produced by detonation or non-detonation synthesis were used
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as reinforcement phase to increase scratch resistance of polyacrylic-based clearcoat. A
strong effect of heat treatment on scratch resistance of coatings was noted (diamond parti-
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cles were heat treated at 450 C for 2 h in air to eliminate nanodiamond carbons and pro-
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duce functional groups on their surfaces). The effect of heat treatment was more
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pronounced for nanodiamonds obtained by detonation synthesis. The surface-functional-
ized nanodiamonds with oleyamine had better dispersion in the polymeric matrix, result-
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ing in an increase in scratch resistance.
The laser surface texturing and diamond-like carbon film deposition reduced poly-
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etheretherketone wear. A 2 μm thick diamond-like carbon film was deposited on the tex-
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tured polyetheretherketone surface.
The enhanced scratch resistance properties were observed in the microcrystalline
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diamond coating in comparison to nanocrystalline diamond coating. The reason for dif-
ferent adhesive characteristics was attributed to the microstructure of the respective coat-
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ings. High tensile stresses were observed in the regions of critical failure which strongly
depended on the magnitude of stress and nature of deformation during the scratch test of
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nanocrystalline and microcrystalline diamond coatings.
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Further details can be found in a review publication.