Wednesday, April 17, 2013

The First Nanomaterial: CorningWare and Controlled Nucleation Grain Growth

Wikipedia, “Nanomaterials is a field that takes a materials science-based approach on nanotechnology. It studies materials with morphological features on the nanoscale, and especially those that have special properties stemming from their nanoscale dimensions.

The recent hub-bub over the sapphire lens cover on the iPhone 5 and proposed use of sapphire as a “coverglass” has the display industry rushing to rediscover the difference between a glass and a crystal, both transparent but not the same thing. In addition to transparent polymers, there is also a class of ceramics that can be transparent as well. The most well-known pyro-ceramic (also called glass-ceramic) is CorningWare. CorningWare is usually visibly white but comes in a transparent version that is trademarked as Visions. In its white version, CorningWare is transparent to radio waves and is commonly used to make “transparencies” for the military and space programs in the form of radomes. Other forms of pyro-ceramics include infrared polarizers widely in use in the telecommunications industry, and two forms of photochromics: one lightens and darken depending on ambient light levels, a second undergoes permanent color changes depending on it's optical exposure during manufacture. All of these products are made possible by a process called controlled nucleation grain growth.

Controlled nucleation grain growth is a process by which a glassy liquid converts to a crystalline form by precise control of the crystallization process. Nano-Crystals are formed in a very controlled manner giving very specific properties to the finished body. This includes extreme hardness and very specific optical properties. These crystals can even be oriented by subsequent processing making the formed part birefringent and enabling its use as a polarizer. Some effort was made to employ the photochromic version as a color filter; however, the process was never able to produce the saturated colors that were necessary. However, this did not stop IBM from filing multiple patents in the area. In addition to cookware and optical products, pyro-ceramics have been investigated as armor for military vehicles and high temperature molds for metal casting. The process was invented in the 1950’s.

That' the ticket Ladie.

1 comment:

  1. The nanocrystaline structure of a pyro-ceram assures that it is both considerably tougher than most glasses and its properties are isotropic. One of the larger problems with a classic crystalline material, such as sapphire, is that the properties are not isotropic. Some planes are stronger than others and the overall properties of a crystalline window depend on which particular plane is cut.


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