Microstructure and mechanical properties of porous Si3N4–SiO2 ceramics fabricated by a process combining carbothermal reduction and sol–gel infiltration–sintering

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 601; pp. 111 - 115
• Main Authors: Cai, Yaohui, Li, Xiangming, Dong, Jiahui
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 17.04.2014; Elsevier
• Subjects: Carbothermal reduction; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Methods of nanofabrication; Physics; Porous; Porous materials; granular materials; Si3N4; SiO2; Sol–gel; Specific materials; Si3N4; Carbothermal reduction; Sol–gel; SiO2; Porous; Carbothermy; Porous materials; Sol-gel; Carbon; Silica; N; Pore size; Sintering; Si; Flexural strength; SiO; Infiltration; Property structure relationship; Porosity; Microstructure; Sol-gel process; Nanomaterial synthesis
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2014.01.087

Porous Si3N4–SiO2 ceramics were fabricated at low–cost by combining carbothermal reduction and sol–gel infiltration–sintering. Using nano–sized diatomite grains as a silica source and dextrin as a carbon source, highly porous Si3N4 ceramics with micron–sized pores were fabricated by carbothermal reduction of diatomite preforms. Si3N4 ceramics fabricated from 20wt% dextrin preforms at 1450°C had the highest flexural strength (13.4MPa), high porosity (80.1%) and small pore size (0.8μm). Using the obtained porous Si3N4 ceramics as preforms, porous Si3N4–SiO2 ceramics were fabricated by silica sol–gel infiltration–sintering. These porous Si3N4–SiO2 ceramics possessed high flexural strength (48.7MPa), high porosity (43.5%) and small pore size (0.4μm).