Title

Reaction Sintering and the Α-Si₃N₄/β′-sialon Transformation for Compositions in the System Si-Al-O-N

Editor(s)

Carter, C. B.

Abstract

The reaction sintering of three powder compositions corresponding to points near theβ′-phase line in the region of z=0.75 has been studied using apparatus which allowed the continuous monitoring of the densification kinetics. The powder compositions were prepared from mixtures ofα-Si3N4, Al2O3 and AIN, and the weight changes in the compacts could be kept to less than ∼ 1% over a two hour period. The densification rate is sensitive to small changes in powder composition and decreases markedly as theβ∼'-sialon phase is approached from the oxygen-side. Theα-Si3N4 toβ′-sialon conversion rate, on the other hand, is almost independent of the powder composition. The sintering and transformation kinetic data, combined with surface area measurements and observations on the microstructure of the sintered compacts, indicate that the sintering behaviour is controlled by at least two processes, namely the vapour phase transport of material and a solution-diffusion-reprecipitation process involving a grain boundary liquid phase. Both processes result in the conversion ofα-Si3N4 toβ′-sialon and result in microstructural coarsening but only the second process leads to overall densification in the powder compact.

Department(s)

Materials Science and Engineering

Keywords and Phrases

Polymer Sciences; Industrial Chemistry/Chemical Engineering; Characterization and Evaluation Materials; Mechanics; Continuum Mechanics and Mechanics of Materials; Crystallography

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 1981 Springer Verlag, All rights reserved.


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