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

Rangaraj, L and Chakrabarti, T and Kannan, R and Jayaram, V (2016) Effect of applied pressure on densification of monolithic ZrCx ceramic by reactive hot pressing. Journal of Materials Research, 31 (4). pp. 506-515. ISSN 08842914

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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 °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: Article
Subjects: CHEMISTRY AND MATERIALS > Chemistry and Materials (General)
Depositing User: Mrs SK Pratibha
Date Deposited: 17 Jul 2018 10:54
Last Modified: 17 Jul 2018 10:54
URI: http://nal-ir.nal.res.in/id/eprint/12899

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