Material properties of vacuum glass

    From the perspective of vacuum technology, vacuum glass can be roughly divided into three categories: quartz glass, hard glass, and soft glass.

     The softening temperature of quartz glass is as high as 1500℃, and the linear expansion coefficient is only 5.8x10^-7/K. However, quartz glass is expensive and has a high helium permeability. It is only used in high-temperature equipment and vacuum equipment that requires ultraviolet light transmission.

     Soft glass has a low softening temperature (490~610℃) and a large linear expansion coefficient (82~92) x10^-7/K. Soft glass is cheap and has low helium permeability. It is often selected as the shell material of the electron tube. This type of glass can be sealed with platinum wire and Dumet wire.

     Hard glass has a higher softening temperature (555~806℃) and a smaller linear expansion coefficient (35~50) x10^-7/K. According to different expansion coefficients, it can be divided into tungsten group glass and molybdenum group glass. Hard glass has a moderate softening temperature, which is convenient for processing and baking and degassing. It has good temperature resistance and is the most commonly used glass in vacuum technology.

(huiputech)