CALCIUM OXIDE

Product Description

Calcium oxide (CaO) is most commonly used as a property modifier component in glass composition. Small amounts of magnesium oxide (MgO), zinc oxide (ZnO), strontium oxide (SrO), and barium oxide (BaO) are also added separately based on application requirements. Calcium oxide can help greatly to accelerate the phase separation of borosilicate glasses (Eguchi et al., 1988; Kokubu et al., 1987; Yazawa et al., 1994). It also has a stabilizing effect on acid resistance (Watzke et al., 1998). It has been found that limiting CaO to small amounts reduces the evaporation of highly volatile sodium and potassium borate compounds during hot forming (Peuchert et al., 2004). If the amount of CaO exceeds certain limit, devitrification is likely to take place. Moreover, heat resistance and alkali resistance also deteriorate with high contents of CaO (Kokubu et al., 1987). Eguchi et al. (1988) has proposed using ZnO to promote ZrO₂ retention in the SiO₂ rich phase at a time of phase separation, thereby maximizing ZrO₂ content in the porous silica-rich skeleton for enhanced alkali-durability.