Chater, Richard

Gasparrini, Claudia

Lee, W.E.

English

Engineering Conferences International

Engineering Conferences InternationalECI Digital ArchivesUltra-High Temperature Ceramics: Materials forExtreme Environment Applications III ProceedingsSpring 4-15-2015An oxidation kinetic analysis of hot pressedzirconium carbide at high temperatureClaudia GasparriniCentre for Nuclear Engineering, Dpt. Materials, Imperial College London (UK)W.E. LeeCentre for Nuclear Engineering, Dpt. Materials, Imperial College London (UK)Richard ChaterDepartment of Materials, Imperial College London (UK)Follow this and additional works at: http://dc.engconfintl.org/uhtc-iiiPart of the Materials Science and Engineering CommonsThis Conference Proceeding is brought to you for free and open access by the Proceedings at ECI Digital Archives. It has been accepted for inclusion inUltra-High Temperature Ceramics: Materials for Extreme Environment Applications III by an authorized administrator of ECI Digital Archives. Formore information, please contact franco@bepress.com.Recommended CitationClaudia Gasparrini, W.E. Lee, and Richard Chater, "An oxidation kinetic analysis of hot pressed zirconium carbide at high temperature"in "Ultra-High Temperature Ceramics: Materials for Extreme Environment Applications III", G. Franks and C. Tallon, University ofMelbourne Eds, ECI Symposium Series, (2015). http://dc.engconfintl.org/uhtc-iii/9Oxidation ofHot Pressed Zirconium Carbide between 800 – 1000 ˚CClaudia Gasparrini a, Richard Chater b  and W.E. Lee aa Centre for Nuclear Engineering, Dpt. Materials, Imperial College London (UK)b Department of Materials, Imperial College London (UK)UHTC: Materials for Extreme Environment  Applications III April 12 – 16 2015, Gold Coast, AustraliaIntroductionMicroscopic cross-section of Triso fuel particles (Image: INL) http://www.world-nuclear-news.org/ENF-Triso_fuel_triumphs_at_extreme_temperatures-2609137.htmlZirconium Carbide has• extremely high melting point (3420 ˚C)• high thermal conductivity (35 W/m · K at 1000 ˚C)• good stability at high temperature and under vacuumThese properties make ZrC a candidate for use in extreme environment applications suchas hypersonic vehicles and as coating materials in nuclear fuels.However a drawback of this material is its low resistance towards oxidation.ZrCcarbide coating material in TRISO particleIts oxidation behaviour can affect the integrity of the material in case of an accident UHTC: Materials for Extreme Environment  Applications III April 12 – 16 2015, Gold Coast, Australia 2Previous ZrC oxidation studiesSystematic study required to get full understanding ofmechanism of ZrC oxidationStarting material ZrCRange of T (K)O2 pressure (kPa)Ea(kJ/mol)Kinetic data Ref Electron beam melted ZrC(99.5% pure)827 – 925 ~ 100 ~ 70 Linear oxidation Kuriakose and Margrave (1964)Zone refined bars (11.2%C)1130 - 2165 0.4 - 44 - Intercrystalline growth and fractureBerkowitz (1967)Hot pressed cylindrical ZrC (0.1% excess C)773 - 1473 21.2 - Effect of porosity on oxidation ratesVoitovich and Pugach(1973)Commercial ZrC 653 - 873 1.3 – 7.9 138 (T<743)180 (T>743)Kinetic data analysis: parabolic diffusion of O2 in ZrShimada et al. (1990)ZrC powder 750 – 810 550 – 1300 5, 20, 5020131.8116Kinetic data, non parabolic diffusion, mechanistic modelRama rao and Venugopal(1994)Zone floated single crystal ZrC0.97873 - 1773 0.02 - 2 - Oxide carbide interface observationsShimada et al. (1995)3UHTC: Materials for Extreme Environment  Applications III April 12 – 16 2015, Gold Coast, AustraliaLiterature controversy3Production of ZrC pelletsSample Atm. Temperature (ºC)Dwell time (h)Pressure (MPa)Dimensions: diameter –height (mm)Density (g/cm3)Relative Density(%)Mean grain size (µm)Batch - 1 Ar 185010(ºC/min)1 50 40 - 5 6,39 96.2 3 - 8Batch - 2 Ar 200010(ºC/min)1 50 40 - 10 6.59 - -Chemical analysis using combustion analysers on crushed and ground hot pressed samples:Zr 0.48 % atomicC 0.47 % atomicO 0.03 % atomicN 0.01 % atomicUHTC: Materials for Extreme Environment  Applications III April 12 – 16 2015, Gold Coast, Australia 4Oxidation of ZrC pellets: chamber lift furnace experimentsOxidation performed at 800 – 900 - 1000 ⁰C (quenching at 0 – 15 – 45 – 60 – 120 – 240 – 360)Fully developed Maltese Cross shape formsWhat is the mechanism of reaction causing this characteristic volume expansion?UHTC: Materials for Extreme Environment  Applications III April 12 – 16 2015, Gold Coast, Australia 5(Zr, C, O) (Zr, C) (Zr, C, O) Furnace oxidation at 800 ⁰COxidation of ZrC pellets: furnace experimentsCross sectional SEM reveals dense pore - free interfaceUHTC: Materials for Extreme Environment  Applications III April 12 – 16 2015, Gold Coast, Australia 6TEM analysis on interface: sample oxidized 1h at 800⁰CSAED pattern suggests monoclinic zirconia at the interface ZrC ZrO2UHTC: Materials for Extreme Environment  Applications III April 12 – 16 2015, Gold Coast, Australia 7TEM specimen taken from ZrC – ZrO2 interface, bright field images reveal nanoclusters which may be the start of the oxidation processTEM analysis on interface: sample oxidized 1h at 800⁰CUHTC: Materials for Extreme Environment  Applications III April 12 – 16 2015, Gold Coast, Australia 8Principle of Focused Ion Beam - Secondary Ion Mass Spectrometry (FIB - SIMS)Secondary Ion Mass Spectrometryhttp://www.nature.com/nrmicro/journal/v5/n9/fig_tab/nrmicro1714_F2.htmlUHTC: Materials for Extreme Environment  Applications III April 12 – 16 2015, Gold Coast, Australia 9PRIMARY ION BEAM Gallium liquid metal ion source SIMS detector measure the mass to charge ratio (m/z) of ions giving the COMPOSITIONof the sampleThe focused beam (Ga+) can be used for IMAGING of the surface or for MILLINGSECONDARY IONS sputtered from the surface are collected and sent to the detectorFIB sputtering analysis : sample oxidized 1h at 800⁰CFIB milling has enhanced the morphology of the interface. SE image after FIB sputtering SE image of ground and polished surfaceUHTC: Materials for Extreme Environment  Applications III April 12 – 16 2015, Gold Coast, Australia 10SIMS - FIB characterization : sample oxidized 1h at 800⁰CSIMS analysis on a clean surface (sputtered via FIB), the chemical composition of these 11 regions have been analysed via FIB – SIMS and EDXZrO2ZrCZrC ZrO2UHTC: Materials for Extreme Environment  Applications III April 12 – 16 2015, Gold Coast, Australia 11SIMS - FIB characterization : sample oxidized 1h at 800⁰CZrO2ZrCUHTC: Materials for Extreme Environment  Applications III April 12 – 16 2015, Gold Coast, Australia 12-50 -40 -30 -20 -10 0 10 20 30 40 500.00.20.40.60.81.0cps/cpsZrC - ZrO2 C norm O norm Zr normCompositional analysis of the interface Normalized signals of Carbon – Oxygen and Zirconium Secondary  IonsEDX analysis on FIB milled area : sample oxidized 1h at 800⁰CZrO2ZrC-50 -40 -30 -20 -10 0 10 20 30 400102030405060708090100% atomicZrC - ZrO2 C % atomic O % atomic Zr % atomicUHTC: Materials for Extreme Environment  Applications III April 12 – 16 2015, Gold Coast, Australia 13Compositional analysis of the interface Carbon – Oxygen and Zirconium  atomic % Conclusions• The oxidation of ZrC has been investigated through a hierarchical level of analysis :MACROSCALE MICROSCALE NANOSCALEoptically SEM / FIB TEMMaltese cross ZrC – ZrO2 Interface m – ZrO2 Oxide Clusters• The interface region where the oxidation reaction occurs has been identified by FIB –SIMS and SEM and its characterization is ongoing via TEM.• No evidence for an oxycarbide intermediate phase is reported, evidence of clusteringof small oxide particles is shown near the interface.• The driving force for the volume expansion seems to be the zirconium diffusiontowards the oxide region.UHTC: Materials for Extreme Environment  Applications III April 12 – 16 2015, Gold Coast, Australia 14AcknowledgementsAnd many thanks to ..Dr Robert Harrison for his help through the workEcaterina Ware for the help in the TEM sample preparationGarry Stakalls for the manufacturing of samplesThanks for your attention!UHTC: Materials for Extreme Environment  Applications III April 12 – 16 2015, Gold Coast, Australia

An oxidation kinetic analysis of hot pressed zirconium carbide at high temperature

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An oxidation kinetic analysis of hot pressed zirconium carbide at high temperature

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