Glass Ceramics

 

glass ceramicsglass ceramics

Image Credit: Macor | ceramics.org

 

Glass ceramics are ceramics that can be fused and then molded, formed, ground, or machined using conventional glass fabrication techniques. After part fabrication, the glass ceramics' structure is transformed by a partial controlled crystallization or devitrification process to form precipitating a crystalline phase or phases in vitreous matrix. Obsidian is a naturally occurring form of glass-ceramic. Glass ceramics are also known as vitrocerams, pyrocerams, vitrocerâmicos, vitroceramiques and sittals. Some vitreous bonds or glass matrix will still be present between the ceramic crystal phases or grain.

 

Glass-ceramics can have zero or very low porosity, high homogeneity, low dielectric constant, low or negative thermal expansion coefficients, low dielectric loss, transparent to opaque appearances, high mechanical strength, and high abrasion resistance. Cerabone®, Bioverit® and other bioactive glass-ceramic can also have a high degree of chemical durability and biocompatibility, which is leading to the use of glass-ceramic teeth and other implant applications. The microstructure or nanostructure of glass-ceramics can be tailored.

 

Types of Glass Ceramics 

The major glass-ceramic system or composition used today include:

  • Li2O x Al2O3 x nSiO2-System (LAS-System)
  • MgO x Al2O3 x nSiO2-System (MAS-System)
  • ZnO x Al2O3 x nSiO2-System (ZAS-System)
  • Lithium disilicate
  • Phlogopite-based materials (a form of mica)
  • MACOR® is widely applied glass ceramic with a fluorine rich glass composition approaching trisilicic fluorphlogopite mica (KMg3AlSi3O10F2). MACOR®is a trademarked proprietary material of Corning Corporation.
  • Ceran®, Ceramat®, Robax®and Zerodur® are widely-applied proprietary glass ceramics from Schott Glass Corporation.
  • Sittal is a glass-ceramic originating from the Russia (Soviet Union) from the Lytkarino Optical Glass Factory.
  • Firelite and Neoceram glass ceramics are produced by the Nippon Electric Glass Company from Japan.
  • Kerablack glass ceramic is a brand of the Eurokera company based in France.