Processes
Glass is a non-crystalline material characterised by the vitreous transition phenomenon. Industrial glasses are mainly obtained by maintaining the chaos of the liquid phase structure. This can be referred to as a non-crystalline solid.
Nowadays, industrial glass is almost all silicate glass. This is essentially a mixture of ceramic oxides. These are recyclable materials that have a low impact on the environment. The raw materials used in their composition are widely available. Glass is manufactured starting with a mixture of different ceramic oxides with silica as the main component (SiO2). Other ceramic oxides act as fluxes, forming or modifying the lattice (B2O3, Al2O3, Na2O, K2O, CaO, MgO, PbO, etc.).
Properties
Optical properties: the transparency of the glass is one of the main properties of most compositions available today on the market. The refractive index may vary, according to their composition, from 1.45 to 2. Their colour is obtained by adding transition metal oxides.
Thermal properties: the thermal expansion coefficient of silica is very low, in the region of 0.55 10-6 °C-1. Low thermal expansion coefficients produce glass that has good resistance to thermal shocks, such as Pyrex for example, which is made of borosilicate glass with an expansion coefficient of 3 10-6 °C-1.
Mechanical properties: Glass is still a fragile material with a tensile strength that rarely exceeds 100 MPa. The process of chemical soaking makes it possible to increase the mechanical properties of glass. Due to the absence of any surface defects, the tensile strength of glass fibres can be very high. This property is therefore exploited to produce composite materials.
Applications
Glass is commonly used to make flat glass for the construction industry. It is also used in the electronics industry for creating all types of screens, in the field of optics for manufacturing solid-state lasers, for fibre optics (sending signals over long distances with minimum attenuation), as well as in the dental industry where its transparency is appreciated when seeking aesthetic qualities.
Glass can also be easily welded to metals. This technique is often used for manufacturing light bulbs or in the field of electronics. If the expansion of glass follows that of metal, it can be used as glass solder.