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[August 2005]
Instant Petrified Wood Yields Super Ceramics
Materials scientists at the US Department of Energy's Pacific Northwest National Laboratory have developed a chemical process that adds a promising new dimension to the search for advanced catalyst technologies, as well as to cutting tools, abrasives and coatings.
Researchers used the process, which is now available for licensing, to create two new ceramic materials that are laboratory versions of petrified wood. These materials combine the hardness of metal with the high surface area of carbon to form metal carbides that are stronger than steel and which can withstand temperatures up to 1400°C.
"The original cellulose structure of the wood acts as a template," said Yongsoon Shin, the PNNL scientist who invented the process. Using a simple chemical process, Shin soaked the wood in acid, then infused it with a source of either titanium or silicon and baked it in an argon-filled furnace.
The result is instant petrified wood in which the silica and titanium take up permanent residence with the carbon left in the cellulose to form the ceramics SiC or TiC.
"The innovations here are the use of a wood template for the formation of a novel-structured SiC or TiC and the use of wood as the carbon source," said Eric Lund, PNNL Commercialization Manager. "The newly formed SiC or TiC exactly duplicates the intricate hierarchical cellulose structure of the wood. It is also possible to create the 'negative' of the wood structure by adjusting the initial acid treatment of the wood."
ENDS