Effect of BPO₄-B₂O₃ Composite Additive on Crystallization and Sintering of Silica Ceramics

Abstract

BPO₄-B₂O₃ composite additive enhanced silica ceramics were successfully prepared by solid phase sintering. The effects of BPO₄-B₂O₃ addition and sintering temperature on the microstructure and phase composition and mechanical properties of silica ceramics were analysed by scanning electron microscopy and X-ray diffraction techniques. The results showed that at 1200°-1400°C, BPO₄-B₂O₃ composite additive formed a glass phase in the sample, filled the pores, and improved the sintering densification of the sample. In addition, the addition of 9 wt% BPO₄-B₂O₃ successfully inhibited the crystallization of fused silica, which significantly improved the mechanical strength of silica ceramics. After sintering at 1200°C for 3 h, the apparent porosity of silica ceramics with 9 wt% BPO₄-B₂O₃ was only 1.33%, and the cold modulus of rupture reached a maximum of 60.99 MPa, which was about 35 times that of pure silica ceramics. It is shown that adding BPO₄-B₂O₃ composite additive provides a feasible method for preparing silica ceramics with good mechanical properties.

GRAPHICAL ABSTRACT

Keywords:

• Fused silica
• BPO₄-B₂O₃
• Crystallization
• Sintering