Mechanism and Kinetics of Oxidation of ZrN Ceramics

Robert W. Harrison, William Edward Lee

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Oxidation of ZrN ceramics from 973–1373 K under static conditions reveals parabolic rate behavior, indicative of a diffusion-controlled process. In-situ high temperature powder XRD found the oxidation mechanism begins with destabilization of ZrN through formation of a ZrN1−x phase with oxide peaks initially detected at around 773 K. The zirconium oxide layer was found to be monoclinic by in-situ XRD with no evidence of tetragonal or cubic polymorphs present to 1023 K. Bulk ceramic samples oxidized at 1173 and 1273 K underwent slower oxidation than those oxidized at 973 and 1073 K. This change in oxidation rate and hence mechanism was due to formation of a denser c-ZrO2 polymorph stabilized by nitrogen defects. This N-doped dense ZrO2 layer acts as a diffusion barrier to oxygen diffusion. However, at an oxidation temperature of 1373 K this layer is no longer protective due to increased diffusion through it resulting in grain boundary oxidation.
Original languageEnglish
Pages (from-to)2205-2213
Number of pages9
JournalJournal of the American Ceramic Society
Volume98
Issue number7
Early online date7 Apr 2015
DOIs
Publication statusPublished - Jul 2015
Externally publishedYes

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