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Effect of applied pressure on densification of monolithic ZrCx ceramic by reactive hot pressing

Rangaraj, Lingappa and Chakrabarti, Tamoghna and Kannan, Rajaguru and Jayaram, Vikram (2016) Effect of applied pressure on densification of monolithic ZrCx ceramic by reactive hot pressing. In: JOURNAL OF MATERIALS RESEARCH, 31 (4). pp. 506-515.

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Official URL: http://dx.doi.org/10.1557/jmr.2016.30

Abstract

The effect of applied pressure on reactive hot pressing (RHP) of zirconium (Zr):graphite (C) in molar ratios of 1:0.5, 1:0.67, 1:0.8, and 1:1 was studied at 1200 degrees C for 60 min. The relative density achievable increased with increasing pressure and ranged from 99% at 4 MPa for ZrC0.5 to 93% for stoichiometric ZrC at 100 MPa. The diminishing influence of pressure on the final density with increasing stoichiometry is attributed to two causes: the decreasing initial volume fraction of the plastically deforming Zr metal which leads to the earlier formation of a contiguous, stress shielding carbide skeleton and the larger molar volume shrinkage during reaction which leads to pore formation in the final stages. A numerical model of the creep densification of a dynamically evolving microstructure predicts densities that are consistent with observations and confirm that the availability of a soft metal is primarily responsible for the achievement of such elevated densification during RHP. The ability to densify nonstoichiometric compositions like ZrC0.5 at pressures as low as 4 MPa offers an alternate route to fabricating dense nonstoichiometric carbides.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the CAMBRIDGE UNIV PRESS, 32 AVENUE OF THE AMERICAS, NEW YORK, NY 10013-2473 USA
Keywords: ceramic; densification; hot pressing
Department/Centre: Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Depositing User: Id for Latest eprints
Date Deposited: 07 Apr 2016 07:22
Last Modified: 07 Apr 2016 07:22
URI: http://eprints.iisc.ac.in/id/eprint/53623

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