Alfano, Davide

Monteverde, Frederic

Savino, Raffaele

Sciti, Diletta

Silvestroni, Laura

English

Engineering Conferences International

Engineering Conferences InternationalECI Digital ArchivesUltra-High Temperature Ceramics: Materials ForExtreme Environmental Applications II ProceedingsSpring 5-14-2012Fabrication, properties, and arc-jet testing ofZrB2-based composites Containing short SiCfibersFrederic MonteverdeISTEC-CNR, ItalyDiletta ScitiISTEC-CNR, ItalyLaura SilvestroniISTEC-CNR, ItalyDavide AlfanoItalian Research Aerospace CentreRaffaele SavinoUniversity of NaplesFollow this and additional works at: http://dc.engconfintl.org/uhtcPart 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 Environmental Applications II by an authorized administrator of ECI Digital Archives. Formore information, please contact franco@bepress.com.Recommended CitationFrederic Monteverde, Diletta Sciti, Laura Silvestroni, Davide Alfano, and Raffaele Savino, "Fabrication, properties, and arc-jet testing ofZrB2-based composites Containing short SiC fibers" in "Ultra-High Temperature Ceramics: Materials For Extreme EnvironmentalApplications II", W. Fahrenholtz, Missouri Univ. of Science & Technology; W. Lee, Imperial College London; E.J. Wuchina, NavalService Warfare Center; Y. Zhou, Aerospace Research Institute Eds, ECI Symposium Series, (2013). http://dc.engconfintl.org/uhtc/6www.istec.cnr.itFabrication, properties and arc-jet testing ofZrB2-based composite containing short SiC fibersDIASUltra-High Temperature Ceramics: Materials for Extreme Environment Applications IIMay 14th 2012, Hernstein (Austria)Frédéric MONTEVERDE*, Diletta SCITI*, Laura SILVESTRONI*Davide ALFANO #, Raffaele SAVINO ^(*) National Research Council of Italy - Institute of Science and Technology for Ceramics(#) Italian Research Aerospace Centre(^) Dept. of Aerospace Engineering – University of Naples Re-entry flight trajectoriesUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012To re-enter Earth’s atmosphere in an alternative way, flying with lower aerodynamicdrag, larger cross range and better maneuverability along more gentle trajectoriesslender vehicles with sharp edges flying at moderate angles of attack are necessary.The reduced leading edge’s curvature radius implies surface temperature higher thanthat of the actual blunt vehicles and that could not be withstood by the conventionalthermal protection system materials.Refractory and oxidation resistant aero-surfaces (with sharp profile) ARE REQUIREDUltra-high temperature ceramicsMelting point range of UHTCs (nitrides, borides and carbides of Zr, Hf, Ta)UHTCs are currently investigated as TPSof fuselage nosecone and wing leading edgesUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012Key requisites for materialsThermal requisites: high thermal conductivity, high emittance, low catalytic efficiency, high resistance to oxidation Mechanical requisites: high resistance to thermal shock, high fracture toughnessMB2 (M=Zr, Hf) ceramics alone possess high temperature capabilities and high thermal conductivity poor oxidation resistance low fracture toughnessUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012Add SiC (particle, whiskers, fibers)Aim of this workStudy of the effects of SiC chopped fibers on ZrB2–based massive ceramic properties resistance to oxidation under static conditions stability under aerothermal heatingUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012Raw materials• ZrB2 - (H.C. Starck) grade B• Si3N4 – Baysind• SiC – HI Nicalon (COI Ceramics)• length: 0.5-1 mm + debris• density: 2.74 g/cm3• composition: 55% β-SiC crystallites (2 nm), 5% C,   embedded in 40% Si-C-O  intergranular phaseUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012Production of ZrB2-15%SiCF Starting composition (vol%): ZrB2 + 15% SiCFiber + 5 % Si3N4 (s.a) Material processing1) Batching of powders3) Drying andde-agglomeration2) Homogenization of the slurry in EtOH6) Hot-pressingFully dense pellet φ 40 mm5.3 g/cm34) Cold linear pressing5) Debonding in ArUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012ZrB2-15 SiCF: microstructure and propertiesPolished section, by SEMmax fiber length: ~ 0.3 mm0.5 mmView plan ⊥ applied PProperty Method Specimen size Notes Mean value (±1s.d)Elastic modulus Resonance frequency 30 x 8 x 0.8 mm RT 402 GPaFlexure strength 4-pt bending 25 x 2.5 x 2 mm RT (453± 19) MPaFlexure strength 4-pt bending 25 x 2.5 x 2 mm 1200°C air (336 ± 29) MPaFracture toughness Chevron notched beam 25 x 2.5 x 2 mm RT (5.3±0.05) MPa√m(∆KIc 50%)Thermal shockresistanceWater quenching method25 x 2.5 x 2 mm RT 400-500°C(in progress)Thermal conductivityLaser flash Φ 12.7 mm RT - 1500°C 65 - 50 W/m KUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012Resistance to oxidation in static airBottom-up loading furnaceIso-thermal run for 30 min at 1700°CSpecific mass change (w/S)(7.5 ±0.1) mg/cm2UHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012Visual appearance before oxidationVisual appearance after oxidationResistance to oxidation in static airIso-thermal run for 30 min at 1700°C0.5 mmPolished cross-section of oxidized bar (SEM micrograph)UHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012Resistance to oxidation in static airIso-thermal run for 30 min at 1700°CBubbles in the outermost glassy coating100 µmPolished cross-section: details of the external oxide scale(SEM micrograph)UHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012Oxidized layersResistance to oxidation in static airoutermost glassy coatingmixed oxide scaleIso-thermal run for 30 min at 1700°C35 µm (depends on the position)45 µm30 µmUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012SiCF - partially depleted ZrB2 regionun-oxidized bulk60 µmArc-jet testingEnergized flow field heats sample’s surface• Simulate re-entry conditions in a ground-based facility• Heat a test gas (air) to plasma temperature by an electric arc, then accelerate into a pressure-controlled chamber, and onto a stationary test articleConvectively            Chemically                RadiativelyIn a re-entry environment:• Oxygen and Nitrogen may be dissociated, thus their recombination adds to surfaceheating• stagnation pressure may be below 1 atm, thus active oxidation of SiC plays an important roleUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012Arc-jet testing in high enthalpy supersonic flowsMain Technical Specifications- Mean free stream total enthalpy (MJ/kg) 3  - 35- Stagnation-point pressure (Pa) 500 – 10000- Mach number up to 5- Mass flow rate (g/s) 0.5  - 5- Gas mixtures air, Ar, N2, CO2- Nozzle exit diameter (mm) 22, 60- Model size (mm) up to 40Main Measurement Techniques- Total enthalpy energy balance- Stagnation-point pressure water-cooled Pitot probe- Stagnation-point heat flux Gardon gauges and slug calorimeters- Pressures precision vacuum transducers- Mass flowthermal mass flowmeters- Surface temperatures IR thermography, pyrometerDept. of Aerospace Engineering - University of Naples “Federico II”, ItalySmall Planetary Entry SimulatorUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012Arc-jet testing_setupHolderNozzle exitPLASMA JETHolder• M ≈ 3 (supersonic regime)• 1 g/s of 80%N2+ 20% O2 (air)• static chamber pressure  ≈ 200 Pa• maximum stagnation point pressure 8.5-10 kPa Two UHTC hemispheres (nominal R= 5 mm)were machinedUHTC hemisphereTwo arc-jet tests were executed1st test:  max H0= 13 MJ/kg for 350 s2nd test: max H0= 17 MJ/kg for 270 sUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012Arc-jet testing_setup• After conventional machining, UHTC hemispheres were cleaned, and weighed before and after arc-jet testing (precision 10-4 g)• The profile of the curved surface was measured before and after arc-jet test using an contact-stylus profilometer• Best fitted R* was estimated along two orthogonal directionsUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012As-machined                    1st test                                   2nd test Visual appearance of hemispheres after• Max H0: 13 MJ/kg, duration (t): 350 s• Equilibrium temperature (by two-color pyrometer)1500°C at t0s 1505 °C at t350s • Spectral emissivity at 1 µm (ε1µm)t0s= 0.86 , t350s = 0.82HolderTwo-color pyrometer1st arc-jet test_resultsUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012As-cut cross section of the hemisphere, by OMε1µm                                                    ε1µm 0.86                                         0.821st arc-jet test_results• Mass change (∆m/m0): 0.4% (all modifications upon the curved surface)• R* (best fitted radius of curvature) change: + 0.007 mm (profilometer)Profile of the round hemispheric surfaceUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012R*=5.007 mm                                                               R*=5.014 mmbefore arc-jet                                                 after arc-jet test• Max H0: 13 MJ/kg, duration: 350 s• Equilibrium temperature range (by two-color pyrometer): 1500 - 1505 °C1st arc-jet test_resultsUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012Polished cross section, by SEM, near the stagnation pointoxide scale thickness 60-65 µm3 mm 1st arc-jet test_results• Max H0: 13 MJ/kg, duration: 350 s• Equilibrium temperature range (by two-color pyrometer): 1500 - 1505 °C65 µmUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012Polished cross section, by SEM: the external oxide layersthickness of zirconia scale 60-65 µm; thickness of glassy coating 4-8 µm50 µm1st arc-jet test_results• Max H0: 13 MJ/kg, duration: 350 s• Equilibrium temperature range (by two-color pyrometer): 1500 - 1505 °CUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 201220 µmSE mode                                                                             BSE modePolished cross section, by SEM: details on the fibers inside the oxide scaleSE: secondary electron, BSE: backscattered electron1st arc-jet test_results• Max H0: 13 MJ/kg, duration: 350 s• Equilibrium temperature range (by two-color pyrometer): 1500 - 1505 °CUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 201220 µmSE mode                                                                             BSE modePolished cross section, by SEM: details on the fibers inside the oxide scaleThe partially –consumed SiC fibers via mechanism of active oxidationSE: secondary electron, BSE: backscattered electron1st arc-jet test_results• Max H0: 13 MJ/kg, duration: 350 s• Equilibrium temperature range (by two-color pyrometer): 1500 - 1505 °CEDS analysis, Au coated surfaceEHT 6 keVUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 201210 µmDetail of a partially oxidized SiC fiber, by BSE-SEMCC SiCooling rate860°C/minSiC + ½ O2(g) = C(s) + SiO(g)SiC + O(g) = C(s) + SiO(g)SiC + O2(g) = SiO(g) + CO(g)SiC + 2O(g) = SiO(g) + CO(g)• Max H0: 17 MJ/kg, duration: 270 s• Equilibrium temperature (by two-color pyrometer)t0-360 = (1800-1820 )°C• Spectral emissivity at 1 µmt0= 0.72 , t270s = 0.68HolderTwo-color pyrometer2nd arc-jet test_resultsUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012As-cut cross section of the hemisphere, by OMε1µm                                                            ε1µm 0.72                                             0.68• Mass change (∆m/m0): + 0.145 % (all modifications upon the curved surface)• R* (best fitted radius of curvature) change: - 0.02 mm (profilometer)before arc-jet                                                 after 2nd arc-jet test2nd arc-jet test_resultsUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012Profile of the round hemispheric surface• R*= 5.013 mm                            R* = 4.993 mm• Max H0: 17 MJ/kg, duration: 270 s• Equilibrium temperature range (by two-color pyrometer): 1800-1820 °C2nd arc-jet test_resultsUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012Polished cross section, by SEM, near the stagnation pointoxide scale thickness 280-170 µm ; no external glassy coating was observed6 mm 2nd arc-jet test_results• Max H0: 17 MJ/kg, duration: 270 s• Equilibrium temperature range (by two-color pyrometer): 1800-1820 °CUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012Zoomed views near (left) and far (right) from the stagnation point(polished cross section, by SE-SEM)100 µm2nd arc-jet test_results• Max H0: 17 MJ/kg, duration: 270 s• Equilibrium temperature range (by two-color pyrometer): 1800-1820 °CUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012Residue of the SiC fiber inside the zirconia scale(polished cross section, by SE-SEM)10 µm2nd arc-jet test_results• Max H0: 17 MJ/kg, duration: 270 s• Equilibrium temperature range (by two-color pyrometer): 1800-1820 °CEXUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012SiC fiber across the reaction interface(polished cross section, by SE-SEM)2 µmSiC fibers near the reaction interface TERIORUn-oxidizedboride inner bulkOxide scalePolished cross section, by SE-SEM2nd arc-jet test_results• Max H0: 17 MJ/kg, duration: 270 s• Equilibrium temperature range (by two-color pyrometer): 1800-1820 °CUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012SiC fiber just below the reaction interface(polished cross section, by SE-SEM)SiC fibers near the reaction interfaceUn-oxidizedboride inner bulkOxide scalePolished cross section, by SE-SEM2 µmArc-jet test_comparison65 µm270 µm65 µm1st test                                         2nd testUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 201250 µmComparison of the external oxide scale (by SE-SEM) near the stagnation point20 µmSummary• ZrB2-15% SiCF were fully densified by hot pressing and characterized• In simulated aero-thermal heating the material withstood rather well the severe environment• The chopped SiCF behaved differently depending on the temperature regimes: in all cases provided a significant benefit to the overall resistance to oxidationUHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012Work in progress• Use more stable SiC fibers• Optimize the max SiC fiber length• CFD modeling to calculate equilibrium temperature map upon the surface (and inside the bulk) UHTC: Materials for extreme environment applications II – Schloss Hernstein, May 13-18 2012F. Monteverde, R. Savino, Dynamic oxidation of ultra-high temperature ZrB2–SiC under high enthalpy supersonic flows, Corrosion Science 53 (2011) 922

Fabrication, properties, and arc-jet testing of ZrB2-based composites Containing short SiC fibers

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Fabrication, properties, and arc-jet testing of ZrB2-based composites Containing short SiC fibers

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