High-strength and low-dielectric ZrO2 reinforced fused silica ceramics by gelcasting

• Published in: Ceramics international 2024-12, Vol.50 (24), p.55240-55250
• Main Authors: Yin, Shuang, Sun, Chengyun, Zhang, Yao, Wan, Wei, Cao, Linjun, Min, Huihua, Fang, Xia, Ma, Haiqiang, Xie, Xinchun, Li, Tianyu, Jiang, Xuewen, Xie, Aiwen, Liu, Liqiang, Zhou, Cong, Zuo, Ruzhong
• Format: Article
• Language: English
• Subjects: Dielectric properties; Fused silica ceramics; Gelcasting; Mechanical properties; ZrO2
• ISSN: 0272-8842
• DOI: 10.1016/j.ceramint.2024.10.377

Herein, the fused silica ceramics integrating good mechanical and dielectric properties were successfully prepared by gelcasting and pressureless sintering by introducing ZrO2 as reinforcement phase. After sintering at 1250 °C for 6 h, the introduced m-ZrO2 underwent a displacive phase transformation from m-ZrO2 to t-ZrO2. More importantly, some t-ZrO2 phases were stably retained to room temperature by doping Y2O3. The ZrO2 phases filled the irregular pores formed by micro-scale fused silica particles, which significantly increased the bulk density from 1.56 g/cm3 for pure fused silica ceramics to 2.07 g/cm3 for fused silica ceramics containing 20 wt% ZrO2. By reason of the increasing bulk density, stress-induced phase transformation toughening, microcrack toughening, and dispersion strengthening, the fused silica ceramics containing 16 wt% ZrO2 displayed the highest flexural strength of 110.6 MPa, which was 83.4 % higher than pure fused silica ceramics. Throughout X-band, the prepared fused silica ceramics with different ZrO2 contents showed good dielectric properties. The dielectric constant and dielectric loss tangent were less than 4.0 and 0.01, respectively. This work demonstrates that combining gelcasting and pressureless sintering is a practical approach for fabricating fused silica ceramics possessing good mechanical and dielectric performance through introducing ZrO2 as reinforcement phase.