Barium Aluminosilicate Reinforced <i>In Situ</i> with Silicon Nitride

Abstract

Advanced ceramic composite materials that exhibit high strength and toughness with good thermal shock resistance are needed for emerging high‐temperature engineering applications. A recently developed in situ reinforced barium aluminosilicate glass‐ceramic shows promise of meeting many of the requirements for these types of applications with the added benefit of low‐cost fabrication through densification by pressureless sintering. The material is toughened through in situ growth of rodlike β‐Si 3 N 4 grains resulting from the α–β silicon nitride phase transformation. Microstructural development and material properties for temperatures up to 1400°C are discussed. When compared to monolithic barium aluminosilicate, barium aluminosilicate reinforced with 70% by volume of Si 3 N 4 shows a significant increase in flexural strength (from 80 to 565 MPa) and fracture toughness (from 1.8 to 5.74 MPa·m 1/2 ) with a high resistance to thermal shock.