Effect of Seeding on the Microstructure and Mechanical Properties of alpha-SiAlON: II, Ca-alpha-SiAlON

Seeding effects on the microstructure and mechanical properties of single-phase Ca-α-SiAlON ceramics have been investigated. Whereas a small amount of seeds can transform the microstructure from one of fine equiaxed grains to one consisting of many needle-like grains, the highest fracture toughness of 8 MPa . m1/2 is not reached until 8% seeding. This contrasts with the much higher seed efficiency in Y-SiAlON, where the peak toughness is reached at 1% seeding. The difference and the general trend of mechanical properties of seeded α-SiAlONs are discussed in terms of α-SiAlON formation and toughening mechanisms. Comments Copyright The American Ceramic Society. Reprinted from Journal of the American Ceramic Society, Volume 85, Issue 5, May 2002, pages 1260-1267. This journal article is available at ScholarlyCommons: http://repository.upenn.edu/mse_papers/36 Effect of Seeding on the Microstructure and Mechanical Properties of -SiAlON: II, Ca-SiAlON Roman Shuba and I-Wei Chen* Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6272 Seeding effects on the microstructure and mechanical properties of single-phase Ca-SiAlON ceramics have been investigated. Whereas a small amount of seeds can transform the microstructure from one of fine equiaxed grains to one consisting of many needle-like grains, the highest fracture toughness of 8 MPa m is not reached until 8% seeding. This contrasts with the much higher seed efficiency in Y-SiAlON, where the peak toughness is reached at 1% seeding. The difference and the general trend of mechanical properties of seeded -SiAlONs are discussed in terms of -SiAlON formation and toughening mechanisms.