Tuesday, September 12, 2006

Fire and Soot

A little heat is often all that is needed to soften metal and make it easy to bend and shape. The oxy-acetylene torch produces a very hot flame that will melt most metals very easily, and works on the principle of a hydrocarbon (acetylene gas) mixed under pressure with an oxidant (oxygen gas) which together result in a very fast, high energy combustion that makes lots of heat.

Here the torch is being used to bend some kind of prototype shock mount for a microphone.

Acetylene is also useful for making carbon nanotubes. Being a hydrocarbon, acetylene will decompose into individual carbon atoms - like a carbon gas - without burning, if you remove all the air from a heated chamber and introduce the acetylene carefully and slowly. I would imagine that an explosion could result if someone forgot to get rid of the oxygen first though I have not heard of any accidents like that in the nano-world, yet.

The heated carbon vapor will just deposit itself as a soot inside the chamber unless it has somewhere specific to go, and that's the trick to making carbon nanorods and nanotubes - you have to have a "seed" for the carbon atom to stick to. Then, amazingly, other carbon atoms seems to line up, almost all by themselves, into a neat circle and stay there, then more carbon atoms go around and around the circle, forming a tube that grows taller and taller.

It's called Self Assembly

So carbon nanotubes are, essentially, soot. Millions of chimneys probably have trillions of carbon nanotubes in them,. But it is a very special, organized soot that has a useful shape that can be used as an antenna, a sensor, a way to deliver a drug or chemical, even a way to strengthen other materials, like microphone ribbons. 

We are in the middle of The Combustion Age.  Combustion Age economics dominate our planet and our technology, the way we eat, move about, and live.

Precursor and early-stage Combustion Age practices and industrialization stimulate rapidly accelerated human population growth. Late-stage Combustion Age practices are severe and brief survival responses to population explosions on this planet.   The need for energy to power things is nearly universal, and a simple way to release stored energy for heat is to burn it.  The consequences of basing an industrialized society primarily upon Combustion are just starting to be realized by a few groups and thought leaders on Earth, but political democracies cannot much influence the root cause of accelerated combustion, which is overpopulation and resource depletion.

robert j crowley

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