Stones at stones' worth

Industrial diamonds can now be produced cheaply

Published: Saturday 30 June 2001

a new process to make diamonds, which are not only the woman's best friend, but also of immense use in industrial processes, could cut the cost of producing the stone drastically. Industries use diamonds as tips of boring bits, among other things, as it is the hardest substance on Earth.

Diamond, a form of carbon, is the hardest substance known to us. It can be used to make a host of things from oil drill bits to brake pads. But making industrial quality diamonds is an expensive process using high pressure and high temperature to convert another form of carbon into diamond. A unique crystalline arrangement of carbon atoms in diamond gives it hardness and lustre to it. Now, researchers at the Drexel University in Texas, usa , have developed a method to produce diamond films that could be used in coating brake pads or other devices. They used silicon carbide as the basic raw material to produce diamonds. Though other processes of conversion have been known, all of them require extreme conditions, thus adding to the costs of producing diamonds. The diamonds produced by this method are minute -- each crystal is only about five nanometres (one nanometre is a billionth of a metre) in size. The new technique operates at ordinary pressures and thus could be used extensively.

Y Gogotsi and colleagues passed a mixture of hydrogen and chlorine gas at about 1,000C over silicon carbide. The chlorine reacted with the silicon and the carbon rearranged into small nanometer-sized diamond crystals and other forms of carbon like graphite ( Nature , Vol 411, p283).

This carbon film has many properties that make it suitable for applications requiring diamond films. It is conducting and porous because of its unusual crystalline structure. Though the technique is still not suitable for largescale production, the researchers are hopeful that it would be easily scaled up for industrial production of diamond-like coating.

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