Glass makes up most of the window. Depending on the frame type, the glazing can make up between 60 and 67% of the total opening. Therefore, it is useful to know more precisely what it is made of and what properties it has.
What is double glazing?
We usually call it Double glazing, Chamber glazing or multilayer glazing. For the technical language it is a insulating glass or just UVA. UVA is a glass that consists of two or more parallel panes that are separated from each other by a spacer. Although the windows do not touch, they are connected by a separator that keeps them away and forms a unit with it and the gas that fills the chamber (air or inert gas) that is closed while the windows are being made into a frame. The adjective « insulating » refers to the properties of multiple glazing, especially its ability to dampen cold and street noise.
The composition of the cup
Up to 95% of the glass consists of SiO2, i. H. Silicon sand. The exact ratio depends on the type of glass being made (usually glass, lead glass, borosilicate glass, etc.).
First, silica is mixed with other ingredients, mainly sodium carbonate or oxide (soda) and calcium carbonate or oxide (lime). Soda acts as a stream and lowers the melting point of silica. Lime acts as a stabilizer and gives the end product toughness and chemical resistance.
The mixture was then heated to about 1500 ° C to give an amorphous substance: glass. Once formed, the vitreous substance goes through a controlled cooling process. In this way we get Sodium-Calcium Glass, which is the cheapest and most commonly used to make panes of glass. PVC windows. It’s usually called a regular or commercial mug.
Properties of commercial glass
Some of the most important and interesting properties of ordinary glass would be:
- Density and weight: The density of the glass is 2500 kg / m3. Therefore, one m2 of a 4 mm thick window weighs 10 kg.
- Hardness and compressive strength: The hardness of glass reaches 470 HK. The window can take loads of up to 800 – 1000 MPa. Therefore it is a hard material and due to the compression it is practically unbreakable.
- Flexural strength: they are only 45 MPa. This is why the glass is easily broken when we try to bend it. It is not shockproof, but it is abrasion resistant.
- Thermal conductivity and thermal expansion: The thermal conductivity of glass reaches 0.8 W / mK and the thermal expansion around 9.10-6 K-1. Therefore, although the vitreous parts react poorly to fire, they can be deformed and broken due to heat.
To compensate for these weaknesses, the glass industry is constantly looking for new solutions. One of them is the production of other glassware than commercial glass. For example, 96% quartz glassware is much more resistant to thermal shock and is used as a laboratory material. Another common option in PVC windowsis the use of tempered glass, which, due to special heat or chemical treatment, is more resistant than ordinary glass to knocks and bends, as well as pressure and thermal shocks.
- Chemical properties: Glass is very resistant to water, alkalis, acids and bases. It only has an effect if it is exposed to alkalis in combination with high temperatures or hydrofluoric acid for long periods of time under normal conditions.
As we can see, glass is a tough and durable product that the glass industry and PVC window manufacturers want to make even stronger through various thermal and chemical processes.