Artificial diamond coatingsthin layers that are almost as tough as real rockhave a number of industrial applications, but they have proved too expensive to use in some cases. Until now, scientists made such nano-crystalline diamond coatings by extracting silicon from silicon carbide under very high pressure or in a high-energy plasma jetboth costly undertakings. In today's issue of Nature, however, Yuri Gogotsi of Drexel University and his colleagues describe a new way to run the same reaction at normal atmospheric pressures in a furnace. Because the new process is more affordable, they suggest that diamond coatings may soon find many new uses.
To create a super-tough film of crystalline carbon, the researchers passed a mixed gas of chlorine and hydrogen over silicon carbide at 1,000 degrees Celsius. The chlorine reacts with the silicon, leaving behind carbon atoms rearranged into an array of forms: nanometer-scale diamond domains, graphite, nanotubes, onion-like carbon and lonsdaliete, which occurs naturally only under meteorite impact craters. The film is porous and conducts electricity and, based on its unusual structure, may well possess other valuable properties. "This is a groundbreaking approach to diamond coating," Robert Hauge of Rice University told Nature Science Update. "It's amazing."