Various Physical Properties Of Vetrosa

    Isotropic: the molecular arrangement of the glass is irregular, and its molecules have statistically uniformity in space. In the ideal state, the physical and chemical properties (such as refractive index, hardness, elastic modulus, thermal expansion coefficient, thermal conductivity, electrical conductivity, etc.) of the homogeneous glass are the same in all directions.Vetrosa

    No fixed melting point: because the glass is a mixture, amorphous, so no fixed melting point. Glass from the solid into a liquid is a certain temperature range (ie softening temperature range) carried out, it is different from the crystalline material, there is no fixed melting point. Softening temperature range Tg ~ T1, Tg for the transition temperature, T1 for the liquidus temperature, the corresponding viscosity were 1013.4 dPa · s, 104 ~ 6dPa · s.Vetrosa

    Metastable: glassy material is generally obtained by the rapid cooling of the melt, from the molten state to the glass transition, the cooling process of rapid increase in viscosity, the particles do not have to do the regular arrangement of crystals, did not release the latent heat of crystallization, Therefore, the glassy matter contains a higher internal energy than the crystalline material, and its energy is between the molten state and the crystalline state, and belongs to the metastable state. From the mechanical point of view, the glass is an unstable high-energy state, such as the existence of low-energy state transition trend, that is, crystallization tendency, so the glass is a metastable solid material.Vetrosa

    Gradual reversibility: The process of the glassy material from the molten state to the solid state is gradual, and its physical and chemical properties are also continuous and gradual. This is obviously different from the crystallization process of the melt, the crystallization process must be a new phase, near the crystallization temperature point, many properties will be mutated. And the glassy material from the molten state to the solid state is completed in a wide temperature range, with the temperature gradually decreased, the glass melt viscosity gradually increased, and finally the formation of solid glass, but the process did not form a new phase. The process of turning the glass into the melt is also gradual.Vetrosa