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Carbon: Introduction
with permission, based on Ian M. Watts book1 and article4
- Density: 2.2gm cm-3
- Melting Point: around 3550°C
- Evaporation Temp.: 2400°C
- Temperature at which a substance has a vapor pressure of 1.33 x 10-2 mbar (arbitrary)
- Average Thickness: 23nm at 5µg cm-2 in nm
- Uses:
- TEM substrates, replicas
- SEM coating of non-conducting samples for x-ray analysis
- EBSD: coating of non-conducting samples with an amorphous layer
- Microprobe: coating of non-conducting samples with highly conductive layer
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Carbon films are uniformly amorphous and highly transparent to electrons because carbon has a low atomic weight. Due to their strongly interconnected three-dimensional network structure, carbon films have remarkable mechanical stability, even when as thin as 1 - 2nm3.
At thicknesses used in electron microscopy from about 2nm upwards carbon films are chemically inert, continuous and basically free from self-structure except for a speckled appearance visible at only the highest magnifications.
Carbon depositions produce a film around the sides and back of specimens without specimen rotation (see EM picture to left). This may be explained by the deflection of light carbon atoms out of straight-line flight by collisions with gas molecules and with the walls or obstructions in a vacuum chamber.
References:
1. Watt IM, 1985. The principles and practice of electron microscopy. Cambridge University Press, ISBN 0-521-25557-0.
2. Bradley DE, 1954. Evaporated carbon films for use in electron microscopy. Br J Appl Phys, 5, 65-66.
3. Hayat MA, 1981. Principles and techniques of electron microscopy, Vol 1 (2nd Ed), University Park Press.
4. Watt IM, November, 1991. Carbon - The electron microscopists most useful element. Microscopy and Analysis, pp 21-23.
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Carbon Rods

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The carbon rods are offered in either spectroscopically pure or technical grades for standard electron microscopy evaporation requirements using carbon coaters. Due to the purification process used all carbon rods we supply have a graphite structure. The purification process removes impurities at a high temperature and causes the carbon to crystallize. The graphite structure has no adverse effects on the carbon coating or the carbon coating process. The user might perceive an additional advantage: the carbon rods (graphite rods) are less brittle than the carbon rods and are easier to handle and easier to shape.
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Technical grade carbon rods have a typical impurity level of around 50ppm or greater.
Typical applications are non critical SEM or SEM/EDS coating of non-conducting samples.
"Spec-Pure" (spectroscopically pure) grade is available for carbon (graphite) rods with
impurities equal or less than 2ppm (single element 1 ppm or less). Typically the impurity
level is more likely 1ppm or less. This grade should be used for TEM, FESEM, FIB, WDS, EBSD, Microprobe
and more critical SEM/EDS applications.
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Sizes of Carbon Rods:

Grade 1 Spec-Pure Carbon Rods
Spectroscopically pure graphite structure carbon rods with an impurity level of 2ppm or less with 1ppm as maximum
level for each element. The rods are all 12" long with three nominal diameters (1/8", 3/16" and 1/4")
to comply with the carbon source used in different high vacuum carbon evaporators. Highly recommended for TEM, FESEM, FIB, WDS, EBSD,
Microprobe and more critical SEM/EDS applications.
| Prod # | Description | Unit | Qty | Price | Order / Quote |
| Carbon Rods, Grade 1 Spec-Pure, 1/8" x 12" (3 x 304mm) | | | |
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| Carbon Rods, Grade 1 Spec-Pure, 3/16" x 12" (4.6 x304mm) | | | |
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| Carbon Rods, Grade 1 Spec-Pure, 1/4" x 12" (6.2 x 304mm) | | | |
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Note: Frequency Specific High Purity Carbon Rods for Cressington coaters
| Prod # | Description | Unit | Price | Order / Quote |
| for 110V, 60 Hz: |
| Carbon Rods, Grade 1 Spec-Pure, 1/4" x 12"(6.15 x 305mm), 60Hz | | |
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| for 220V, 50 Hz: |
| Carbon Rods, Grade 1 Spec-Pure, 1/4" x 12"(6.15 x 305mm), 50Hz | | |
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Grade 2 Carbon Rods, Technical Grade
Technical grade graphite structure carbon rods contain impurities typically equal to or less than 50ppm. However, as an exception some batches can contain impurities up to 200 ppm. The impurities typically consist of: (ppm max.): Ca 20, Fe 20, Cr 10, Si 2-5, Ti 8-10, V 4-4 and traces of other elements. Use this grade for non-critical SEM and SEM/EDS applications.
| Prod # | Description | Unit | Qty | Price | Order / Quote |
| Carbon Rods, Technical Grade, Grade 2, 1/8" x 12" (3 x 304mm) | | | |
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| Carbon Rods, Technical Grade, Grade 2, 3/16" x 12" (4.6 x304mm) | | | |
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| Carbon Rods, Technical Grade, Grade 2, 1/4" x 12" (6.2 x304mm) | | | |
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PELCO® Double-Pointed Carbon Rods - Grade 1
All pointed carbon (graphite) rods are made from spectroscopically pure
(impurities <2ppm, no element more than 1ppm) graphitized carbon.
Pointed carbon rods give improved evaporation procedures and enable consistent carbon coating.
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Double-Pointed Carbon, .120" (1/8") dia. x 2-1/4" long (3.05 x 57.1mm),
Tip: .039" dia. (1.0mm), neck type tips
| Prod # | Description | Unit | Qty | Price | Order / Quote |
| Double-Pointed Carbon Rods, 1/8" dia. x 2-1/4" L (3.05 x 57.1mm) | | | |
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Double-Pointed Carbon, .180" (3/16") dia. x 2-1/2" long (4.6 x 63.5mm),
Tip: .039" dia. (1.0mm), neck type tips
| Prod # | Description | Unit | Price | Order / Quote |
| Double-Pointed Carbon Rods, .180" dia. x 2-1/2" L (4.6 x 63.5mm) | | |
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Double-Pointed Carbon Rods, 1/4" dia. x 2" long (6.4 x 50.8mm),
Tip: .039" dia. (1.0mm), neck type tips
| Prod # | Description | Unit | Price | Order / Quote |
| Double-Pointed Carbon Rods, 1/4" dia. x 2" L (6.4 x 50.8mm) | | |
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Double-Pointed Carbon Rods, 1/4" dia. x 1-1/2" long (6.4 x 38mm),
Tip: .056" dia. (1.4mm), neck type tips
| Prod # | Description | Unit | Qty | Price | Order / Quote |
| Double-pointed Carbon Rods 1/4" dia. x 1-1/2" L (6.4 x 38mm) | | | |
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Double-Pointed Carbon Rods, ø6.2 x 38mm long (ø1/4" x 1-1/2" L),
Tip: 3.8 / 1.6mm (.15 / .066") double neck for Cressingtion carbon coaters
| Prod # | Description | Unit | Price | Order / Quote |
| Pointed Carbon Rods, Double Neck Tip, ø6.2x38mm long (ø1/4"x1-1/2" L), 60Hz | | |
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| Pointed Carbon Rods, Double Neck Tip, ø6.2x38mm long (ø1/4"x1-1/2" L), 50Hz | | |
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| Use Carbon Rod Sharpener, Prod. No. 57-10, for re-sharpening graphite tips |
| Two Step Carbon Rod Sharpener, for 1/4" rods (Cressington 108C & 208C) | | |
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| Replacement Blades for Two Step Carbon Rod Sharpener, for 1/4" rods | | |
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PELCO® Single-Pointed Carbon Rods - Grade 1
spectroscopically pure, <2ppm
no element more than 1ppm
Nominal Diameters:
1/8" (3mm or 0.120" real)
1/4" (6.2mm or 0.242" real)
Rod Length: 2-3/8" (60.3mm)
Neck Length: 0.205" (5.2mm) Neck Diameter: .045" (1.14 mm)
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| Prod # | Description | Unit | Price | Order / Quote |
| Carbon Rods, 1/8" dia. x 2-3/8" L (3 x 60.3mm), neck tip, single point | | |
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| Carbon Rods, 1/4" dia. x 2-3/8" L (6.2 x 60.3mm), neck tip, single point | | |
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Hand Carbon Rod Sharpener
Simple hand tool for sharpening Carbon rods into 1 millimeter cylindrical tips. Rod is inserted into tool and rotated by hand against an adjustable tungsten carbide cutter to the desired length.
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| Prod # | Description | Unit | Price | Order / Quote |
| Hand Carbon Rod Sharpener, for 1/8" size (3mm) rods | | |
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| Hand Carbon Rod Sharpener, for 1/4" size (6.2mm) rods | | |
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| Cutter Replacement for Carbon Rod Sharpener | | |
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Two Step Carbon Rod Sharpener
Hand tool for creating two step carbon rods for the Cressingtion Carbon Coaters.
Graphite rod is inserted into tool and rotated by hand against two pre-set tungsten
carbide cutters to achieve the correct steps. Comes with brass adjustment tool.
| Prod # | Description | Unit | Price | Order / Quote |
| Two Step Carbon Rod Sharpener, for 1/4" rods (Cressington 108C & 208C) | | |
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| Replacement Blades for Two Step Carbon Rod Sharpener, for 1/4" rods | | |
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Three Step Carbon Rod Sharpener
For creating a three level tip on 1/4" size (6.4mm) carbon rods. Offset is adjustable.
| Prod # | Description | Unit | Price | Order / Quote |
| Three Level Carbon Rod Sharpener, for 1/4" size rods | | |
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Possible carbon pointed rod shapes and their setups. The right illustration, with neck rods, is usually preferred.
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Carbon Powder
high purity +/- 2ppm, two types
4 oz. (113g) packages
Fine carbon powder in graphite form. Very high purity with trace elements less than a total of 2 ppm. Trace elements can be Si, Al, Fe, Mg, Ca ro B. Graphite flake size is 200 mesh (75% through 100 mesh). Can be used for pelletizing or mixing with resins or epoxy to make them conductive. Sold in 4 oz. (113g) container.
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| Prod # | Description | Unit | Qty | Price | Order / Quote |
| SP-1 Natural Flake Graphite Powder, good for pelletizing |
| SP-1 Natural Flake Graphite Powder, 200 mesh | | | |
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| SP-2 Synthetic Graphite Mixing Grade |
| SP-2 Synthetic Graphite Powder, 200 mesh | | | |
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Carbon Rod Hand Drill
for making recessed carbon rods
Chrome plated device has an internal, adjustable twist drill for boring out a recessed area in the ends of 1/4" carbon rods. Recessed carbon rods permit the addition of a metal to create a blend of pure graphite/carbon and another appropriate material for shadowing (i.e. Pt). Drill size is #45 (.082"). Drill depth is adjustable and set with a hex nut. Hex key is included.
| Prod # | Description | Unit | Price | Order / Quote |
| Carbon Rod Hand Drill | | |
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Pre-Drilled Carbon Rods
for the addition of another material for shadowing
Recessed carbon rods come in two sizes:
0.120 dia x 2.44" long with a .063" dia x 0.10" deep on both ends
0.244 dia x 2.25" long with a .082" dia x .085 deep on both ends
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| Prod # | Description | Unit | Price | Order / Quote |
| 0.120 dia Pre-Drilled Carbon Rods | | |
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| 0.244 dia Pre-Drilled Carbon Rods | | |
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Page Last Updated: May 21, 2010