Nanotechnology applied to glass surface protection.

Generally, we are accustomed to consider glass an inert and durable material with high chemical stability. In addition to its apparent inertia, glass has a lot advantageous properties, such as its transparency or the ability to take any color as the result of the addition of small amounts of transition metals. In fact it has been extensively used, thanks to its unique mechanical and chemical–physical properties, from ancient until modern times. Before describing the structure of glass it is important to define the term “glass”. The definition given by the American Society for Testing and Material is: “Glass, is an inorganic product of fusion which has cooled to a rigid condition without crystallizing”. In particular we are concerned with oxide glasses based on silica: the alkali-alkali earth-silica family of glasses. The first theory of the structure of glass to become widely accepted was that of Zachariasen (1932), called the random network theory. This theory explains many characteristics of glassy state such as: a) The optical isotropy of glasses results from the random atomic arrangement. b) In a random network no two atoms occupy exactly identical sites and so the lack of abrup