chemical properties

Glasses consist of a mixture of various components. Their properties, mainly depending on the composition as well as the thermal history of the material.

The common feature of glasses is their isotropic structure associated to the absence of long range order. The improvement of their properties has increased the number of glass applications :

• the optical properties: most of the glasses are transparent because they don't contain transition elements which could interact with incident visible beam.
• the mechanical properties: the glass has an elastic and brittle behaviour
• the chemical properties: the corosion of glass when in contact with aqueous solution requires long time
• the thermal properties : the glass is a good thermal insulator
• the electrical properties: the glass turns into an insulator in low temperature. When heated at high temperature, it shows an ionic conductivity.
• the viscosity : this property is among the main feature of oxide glasses. The glass is "an extremely viscous liquid ". This viscosity varies according to the temperature and has to be known to control the glass processing ( melting, glass blowing, annealing )
• the surface tension plays a significant role during the different stages of glass manufacturing.

a main property of glass to be formed : its viscosity