Guest Writer - Gastautor - Gast Schrijver


Akira SAWAOKA

President, Daido Institute of Technology and Project
Leader, Japan Aerospace Exploration Agency (JAXA)

 

 

Inspiration from outer space
Synthesizing artificial diamonds using shock pressure


Since ancient times, man has imagined an unknown world when looking up at the starlit sky. As observational technologies developed, however, space went from being an imagined world to a scientific one, as well as a source of discoveries and new ideas.

The universe has also provided a reason for Prof. Sawaoka to become enthusiastic about researching diamonds when he was studying the synthesizing of substances by using shock pressure. Hexagonally structured diamonds made from graphite under high pressure generated by a meteorite impact were found in a meteor crater. He had another inspiration from space, specifically Jupiter, the huge planet made of hydrogen and helium gases. Theoretical physics predicts that hydrogen is in the metallic state at the core of the planet under several tens of millions of atmospheric pressure. All substances including diamonds can be metallized under such high pressure, according to calculations based on theoretical physics. If it is realized, novel properties may be discovered.

Prof. Sawaoka says, "When it was said in 1969 that one would win a Nobel Prize if one could create metal diamonds, I decided to make the idea come true." His goal was to create metal diamonds by using shock pressure. All he succeeded in doing in his laboratory, however, was to create very small diamond particles with 50 to 100 nm in diameter. He said, "I didn't think these small diamonds could be used in actual applications." He tried to use them as industrial materials by consolidating them. Ordinary diamonds are very hard but tend to cleave when force is applied to them in a certain direction. But carbonade, a type of natural diamond mined mainly in Brazil, is a tough aggregate composed of very small diamond crystals and thus it is more suitable for machine tools. He came up with the idea of consolidating powdered diamonds with shock pressure to produce golf ball-sized diamond aggregates. He expected that these could be used as rock drills for digging oil wells and tunnels. But this was not an easy task. Diamond powder cannot be consolidated easily and becomes graphite again with increasing its temperature to consolidate. His attempt failed although he tried various methods including changing temperature, pressure, shock pressure and other conditions. Whenever he tried to enlarge the aggregates to a certain size, they cracked.

But his research on synthesizing diamonds with shock pressure led to the production of fine diamond powder called "SCM Diamond," made from graphite. He succeeded in producing diamond powder by using only 30 to 50 kg of explosives, compared with 1,000 to 2,000 kg of explosives used in other methods. In his method, the volume of explosive used can be reduced by maintaining high pressure longer through reflecting shock waves of the explosion. In 2000, half of all diamonds produced globally with shock pressure were synthesized using his method.

Prof. Sawaoka has been involved in experimental projects of the National Space Development Agency of Japan (now the Japan Aerospace Exploration Agency) since 1979. He is now the leader of the agency's applied research project being conducted in the International Space Station. He says, "Space development is a history of failures and delays. It has never moved forward as planned. The development involves long-term efforts by people involved in it, who come and go.
A senior person who has been participating in space development for many years and who has much knowledge about the history of this development is needed." He has also been saying openly that he will become an astronaut. He says, "I want to be rewarded for working behind the scenes for many years. My goal is not just a dream; it will come true." It may not be long before we will see the Japan's oldest astronaut travel to space.
(Interviewer: Yu Tatsukawa, Cosmopia Inc.)

For more information,
http://www.nanonet.go.jp/english/mailmag/2004/024a.html


Akira SAWAOKA