SPG Mid-Tester Equipment

SPG Mid-Tester Equipment

SPG (Shirasu Porous Glass) is a new material that Miyazaki Prefectural Industrial Laboratory developed in 1981 by use mainly of Shirasu that is abundant in South Kyushu.  SPG is applied as multi-function glass because of having innumerable pores of uniform micron size, which can freely be changed.
Base glass of SPG is synthesized from Shirasu, lime and boric acid at about 1350°C, and then formed. When the base glass is heated, a phenomenon called "phase separation" occurs in the fiber structure of the glass. CaO⋅B₂O₃ is a component that is easy to dissolve in acid and, therefore, elutes from the base glass when subjected to acid such as hydrochloric acid. Then a glass porous body composed mainly of Al₂O₃⋅SiO₂ glass is formed.  This is SPG.