The chemical composition of ordinary glass is Na2SiO3, CaSiO3, SiO2 or Na2O CaO 6SiO2, etc. The main component is silicate double salt, which is an amorphous solid with irregular structure. Widely used in buildings, used for wind and shading, belonging to a mixture.
Extended data:
Characteristics of glass:
1, no fixed melting point
Because glass is a mixture, it is amorphous and has no fixed melting point. The transition of glass from solid to liquid is carried out in a certain temperature range (that is, the softening temperature range), which is different from crystalline substances and has no fixed melting point. The softening temperature range is Tg~T 1, Tg is the transition temperature, and T 1 is the liquidus temperature.
2. Metastability
Generally speaking, glassy substances are obtained by rapid cooling of the melt. When the melt is transformed into glassy, the viscosity increases sharply during the cooling process, so that the particles can not be arranged regularly to form crystals, and the latent heat of crystallization can not be released. Therefore, glassy substances contain higher internal energy than crystalline substances, and their energy is between molten and crystalline substances, which belongs to metastable state.
3. Progressive reversibility
The process of glassy substances from molten state to solid state is gradual, and the changes of their physical and chemical properties are also continuous and gradual. This is obviously different from the crystallization process of melt. During the crystallization process, new phases will inevitably appear, and many properties will suddenly change near the crystallization temperature.
However, the transition of glassy substances from molten state to solid state is completed in a wide temperature range. With the gradual decrease of temperature, the viscosity of glass melt gradually increased, and finally solid glass was formed, but no new phase was formed in the process. On the contrary, the process of heating glass into melt is also gradual.