INTELLIGENCE

IN GRAPHITE

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EXPANDED & PROCESSED EXPANDED GRAPHITE.

TECHNICAL INFORMATION

BLACK MAGIC.EXPANDED GRAPHITE AND PROCESSED EXPANDED GRAPHITE Due to the layered structure of graphite, atoms or small molecules can be introduced between the carbon layers (intercalation). During this process a so-called expandable graphite salt or GIC (Graphite Intercalation Compound) is produced. Outstanding expandable graphite grades have a high proportion of intercalated layers. Usually sulphur or nitrogen compounds are used as intercalation agents.

Under the influence of heat the layers separate like an accordion, and the graphite flakes expand. Depending upon the grade of material expansion can commence at as low as 180°C and can occur suddenly and rapidly. In the case of free expansion the final volume can be several hundred times greater than the initial volume.

The properties of expandable graphite, i.e. initial expansion temperature and degree of expansion, are primarily defined by the quality of intercalation (proportion of intercalated layers) and by the intercalation agent.

The volume that results from the thermal expansion process depends on the process temperature. Exfoliated packs of graphite layers are created during the process. They show, compared to the original material, a very low apparent density and a significantly higher surface area. The latter of those properties make this material predestined as an electrically conductive filler for batteries, plastics and ceramics.

EXPANDED GRAPHITE

Natural graphite

Graphite layers with intercalated molecules

INTERCALATION AGENT

Processed expanded graphite (EXG)

Expanded graphite

HEAT

Graphite foil

SC Graphite

PROCESSING

COMPRESSING

PROCESSING

EXPANSION PROCESS

FIELDS OF APPLICATION

Battery systems Coatings, plastic foils Rubber products, e.g. conveyer belts Manufacturing graphite foils Heating and cooling systems Energy storage systems Sealing systems High temperature applications

ADVANTAGES

Halogen free Free of heavy metals Suitable for a wide range of applications Chemically inert Corrosion resistant Not harmful to health Excellent electrical and thermal conductivity Flexible Heat resistant Oxidation resistant

ELECTRICAL CONDUCTIVITY OF SC GRAPHITE

UF 2 99.5 : Natural graphiteSC: Expanded graphite grades

THERMAL CONDUCTIVITY IN POLYPROPYLEN (PP) AND POLYAMID (PA)

RFL : Natural graphiteSC: Expanded graphite grades

Filling level (%)Filling level (%)

Spec

. con

duct

ivit

y (S

/cm

)

Ther

mal

con

duct

ivit

y (W

/mK

) at

25 °

C

EXPANDED GRAPHITE

Graphit Kropfmühl GmbH Langheinrichstr. 1 94051 Hauzenberg GERMANY T: +49(0)8586 609-0 | F: -112 info@gk-graphite.com www.gk-graphite.com

EXPANDED GRAPHITE

EXPANDED GRAPHITE

GRADE CARBON CONTENT IN % SURFACE AREA

EXG 9820 min. 98 > 20 m2/g

EXG 9840 min. 98 40 m2/g

GRADE CARBON CONTENT IN % PARTICLE SIZE

SC 5 O 99.2d10: 2.2 µmd50: 5.1 µm

d90: 10.6 µm

SC 20 OS 99.0d10: < 7.7 µm

d50: 18 - 24 µm d90: < 75 µm

SC 3000 O/SM 99.0 max. 15 % > 2000 µm

SC 4000 O/SM 99.0 max. 20 % > 4000 µm

SC 8000 O/SM-F 99.0 max. 15 % < 1000 µm min. 50 % > 2000 µm

PROCESSED EXPANDED GRAPHITE

EXG 9820 SC 3000 O/SM SC 20 OS