The glass is an amorphousbody with mechanical properties similar to a solid, as a result of supercooled molten materials, mainly minerals and other inorganic raw materials, without crystallization. The lack of order structures in the area of liquid glass approaching, rigidity and fragility – for solids. A condition in which there is a glass (vitreous), is a condition that a thermodynamically (after a long time can lead to crystallization, by weight, of the ingredients in the glass, which leads to the deterioration of its mechanical parameters).
The construction glass properties
Good glass transmits visible radiation (80-90%), has a high compressive strength, but little on the bending and stretching, it is fragile. Glass does not have a specific melting point but the heating within a range of temperatures will soften gradually, going from fragility to chewy, and finally liquid state. This specific property is used in the formation of the glass with both usable (glassware, bottles, etc.).
The basic parameters of construction glass according to PN-EN 571-1:2005 are as follows:
- the density at 18 ° c: ρ = 2500 kg/m3
- hardness: 6 on the Mohs scale
- Young’s module: E = 70 GPa
- Poisson number: µ = 0,2
- specific heat: c = 720 J/(kg • K)
- coefficient of linear expansion: α = 9 • 10-6 K-1
- thermal conductivity: λ = 1/(m • K)
- the average refractive index: n = 1.5
The types of glass
Flat glass construction may be produced using one of the three basic methods. Depending on the method produces the following types of glass:
- Float glass is produced one of the most modern methods of forming, which consisted in the fact that melted Fritos is solid on the surface of the molten metal (pewter), located in the hot tub flotacyjnej and heated the atmosphere. On the surface of the metal hot Fritos, influenced by the forces of gravity and surface tension, takes the form of plates almost parallel planes. The glass float method produced give very small deformation of the image suitable for modifying layer deposition. Today, most of the glass used in housing and in public buildings is float glass.
- Drawn glass is a glass produced an older method, consisting in the fact that in the tub Fritos to a suitable viscosity is the “pull-out” by the system. In the process of drawing is glass, material is cooling down and annealing, creating a glass plate. The main disadvantage of glass drawn is waviness, and what goes with it distortion of watching through the glass of the picture. This defect prevents the use of glass drawn to produce modern glass particle spray. Before distributing the production of insulating glass was drawn massively used for glazing of Windows, currently used for glazing of industrial buildings, greenhouses, etc.
- Rolled glass is created by passing the glass mass between the counterrotating rollers. Currently, this method produced glass reinforced (a metal grid), patterned glass, ornamental glass and glass profiled.