Alumina glass made in bulk

Researchers from 3M's Central Research Laboratory have found a way to make non-silica glasses in bulk.

Non-silica glasses are stronger than traditional silica glasses, but existing manufacturing methods only allow for fibers or thin films. The researchers' process allows them to mold or machine complex shapes while the material is amorphous, then crystallize it into a hard ceramic.

The material does not break as easily as silica glass, is not subject to frosting due to chemical etching, is very resistant to scratching, and has a higher index of refraction and transmits light through a broader spectrum of wavelengths than silica glass. This makes it appropriate for wide range of objects, including cutting tools, medical implants, kitchenware, space-ship tiles, optical signal amplifiers and thin, durable eyeglasses, according to the researchers.

The researchers' made the material by first generating glass beads of about 100 microns in diameter. A micron is one-thousandth of a millimeter. They then sinter the beads into an amorphous material by heating them to a temperature between the glass transition temperature and the glass crystallization temperature.

The result is a glassy, or non-crystal, material containing nanoscale crystals.

The bulk glass material could be produced for practical uses like kitchen tiles within a few years; more complicated optical devices will take longer, according to the researchers. The work appeared in the August 12, 2004 issue of Nature.