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| Researchers clear way to stronger glass Researchers at the University of Wisconsin-Madison have developed a new glass-making technique. With the new technology they created a novel glass that is stronger and more stable than glass made in traditional ways. When considered at the molecular level, most solid materials can be described as either crystals or glasses, explains lead author Mark Ediger, a UW-Madison chemistry professor. The difference lies in the degree of internal organization of their constituent molecules. Just as levels of messiness can range from cluttered to chaotic, levels of molecular disorder can vary between different types of glass. Glasses composed of more organized molecules are more stable and durable, while glasses with haphazard molecular assemblies are less stable and may degrade over time. Conventional glasses are relatively disordered and molecularly unstable because of how they are made. Glass ingredients are melted, then cooled and allowed to harden. Normally, a piece of glass is allowed to cool all at once and the inner molecules, unable to move freely, tend to be trapped in disarray. Ediger and his team designed a new technique that gives all the molecules a chance to arrange themselves a little more neatly. They build glass layer by layer using a method called 'vapor deposition'. Glass is heated to the point of evaporation and allowed to condense on a cold surface, where the vapor forms an ultrathin liquid film. By adding layers to the surface one at a time, each sheet of particles can move into a more organized arrangement before solidifying. Though the new glasses do not reach the precision of crystals, they are denser and far stronger than traditional glass. Ediger estimates that the more stable glass would take at least 10,000 years to make using conventional technology, because the liquid glass would have be cooled extremely slowly. With the new vapor deposition method, it takes about an hour. For now, the Wisconsin researcher has no expectations of using the method for large items like window glass. The microscopic scale of the layering technique makes it best suited for thin films and small products. write your comments about the article :: © 2006 Construction News :: home page |