SWCNT synthesis

Fraunhofer IWS

SWCNT synthesis based on pulsed arc process

SWCNT synthesis is possible via physical vapor deposition (PVD) processes. In contrast to the commonly used continuous arc process, IWS engineers use a unique pulsed arc process. A pilot line was set up, which includes numerous in-house developments.

The manufacturing process is continuous and shows the greatest potential for SWCNT mass production compared to alternative approaches (PVD: continuous arc process, laser ablation and chemical vapor deposition (CVD): thermal CVD, high pressure carbon monoxide (HiPCO)-process).

Principle design of the IWS SWCNT manufacturing line based on pulsed arc technology. Right: synthesis reactor with anode and cathode, left: second part of the reactor for functionalization processes.

The IWS process is performed in a dual chamber quartz tube reactor. Both parts are connected via flexile and thermally well-insulated metal adapter. The synthesis reactor (in image right side) is responsible for SWCNT synthesis. The second part of the reactor is used to functionalize the material. The synthesis reactor contains as central elements the anode, which contains graphite and various metal catalyzers, and the cathode made from graphite. An electric voltage is applied to these electrodes. An arc discharge develops, which melts and evaporates the anode target material.

A carrier gas (helium or argon) is injected into the reactor from the right side. The gas transports the evaporated material out of the synthesis zone through the furnace. Additional reaction gases such as CO2 can be injected via nozzles for functionalization purposes.

The second part of the reactor (in image left side) contains cooling fingers. The produced material condenses on these fingers. Most of the material however will only deposit in the then attached gas washer.

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