Title

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

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.

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)

222461

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 1999 Kluwer Academic Publishers, All rights reserved.

Link to Full Text


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