Effect of AlN and Al₂O₃ Additions on the Phase Relationships and Morphology of SiC. Part I. Compositions and Properties

Author

Greg Hilmas, Missouri University of Science and TechnologyFollow
Tsengying Tien

Abstract

X-ray diffraction was utilized to follow the transformation from β-SiC (3C) to the various α-SiC polytypes in the presence of AlN and Al₂O₃ additives after hot pressing from 1700 to 2100⁰C. The 2H- and 6H-polytypes of α-SiC were the predominate polytypes with additions of only AlN or Al₂O₃, respectively. The amount of 2H- and 6H-polytypes, and subsequently the microstructural morphology of the SiC materials, were found to be controlled by varying the amount of AlN and Al₂O₃. Improvements in fracture toughness to approx. 9 MPa-√m were achieved with flexural strengths ranging from 600 to 900 MPa. These results suggest that accurate control of the polytypic make-up of SiC-based materials, along with their mechanical properties, can be achieved through AlN and Al₂O₃ additions.

Recommended Citation

G. Hilmas and T. Tien, "Effect of AlN and Al₂O₃ Additions on the Phase Relationships and Morphology of SiC. Part I. Compositions and Properties," Journal of Materials Science, vol. 34, no. 22, pp. 5605 - 5612, Kluwer Academic Publishers, Nov 1999.

The definitive version is available at https://doi.org/10.1023/A:1004793302482

Department(s)

Materials Science and Engineering

Keywords and Phrases

Alumina; Aluminum compounds; Bending strength; Crystal microstructure; Fracture toughness; Hot pressing; Mechanical properties; Morphology; Phase transitions; Temperature measurement; X ray diffraction analysis; Aluminum nitride; Polytypes; Silicon carbide

International Standard Serial Number (ISSN)

0022-2461

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 1999 Kluwer Academic Publishers, All rights reserved.

Publication Date

01 Nov 1999