Properties Of Vetrosa
No fixed melting point: Because the glass is a mixture, not a crystal, so there is no fixed melting point. Glass from solid to liquid is a certain temperature area (that is, the softening temperature range), it is different from crystalline matter, there is no fixed melting point. The softening temperature range is tg~t1, TG is the transition temperature, T1 is the liquid phase line temperature, the corresponding viscosity is $number. 4 Dpa·s, 104~6dpa·s.Vetrosa
Metastable: Glassy matter is generally obtained by the rapid cooling of the melt, from the molten state to the glass state, during the cooling process, the viscosity increases sharply, the particles have no time to do the regular arrangement to form crystals, no crystallization latent heat is released, so the glassy matter is higher than the crystalline matter, and its energy is between the molten state and the crystalline state, which belongs to the metastable state. From the point of view of mechanics, glass is a kind of unstable high energy state, such as the trend of low energy state transformation, that is, crystallization tendency, so, glass is a metastable solid material.Vetrosa
Degenerate reversibility: The process of glassy matter from molten state to solid state is gradual, and its physical and chemical properties are continuous and gradual. This is obviously different from the crystallization process of the melt, the crystallization process must appear new phase, in the vicinity of crystallization temperature point, many properties will occur. And the glassy matter from the melting state to the solid state is done in the wider temperature range, as the temperature gradually decreased, the glass melt viscosity gradually increased, the final formation of solid glass, but there is no new phase formation. Conversely, the process of heating the glass into a melt is also gradual.Vetrosa
Isotropic: The molecular arrangement of glass is irregular, and its molecule has statistical uniformity in space. In ideal condition, the physical and chemical properties of homogeneous glass (such as refractive index, hardness, elastic modulus, thermal expansion coefficient, thermal conductivity, conductivity, etc.) are the same in all directions.