Fahrenholtz, W.G.

Hilmas, G.E.

English

Engineering Conferences International

Engineering Conferences InternationalECI Digital ArchivesUltra-High Temperature Ceramics: Materials ForExtreme Environmental Applications II ProceedingsSpring 5-14-2012Ultra-High Temperature Ceramics: HistoricPerspectives and Recent ProgressW.G. FahrenholtzMissouri University of Science and TechnologyG.E. HilmasMissouri University of Science and TechnologyFollow 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 CitationW.G. Fahrenholtz and G.E. Hilmas, "Ultra-High Temperature Ceramics: Historic Perspectives and Recent Progress" in "Ultra-HighTemperature Ceramics: Materials For Extreme Environmental Applications II", W. Fahrenholtz, Missouri Univ. of Science &Technology; W. Lee, Imperial College London; E.J. Wuchina, Naval Service Warfare Center; Y. Zhou, Aerospace Research InstituteEds, ECI Symposium Series, (2013). http://dc.engconfintl.org/uhtc/2Ultra-High Temperature CeramicsHistoric Perspective and Recent ProgressW.G. Fahrenholtz and G.E. HilmasMissouri University of Science and TechnologyRolla, MO 65409 USAHistoric Context• Boride and carbide synthesis noted as far back as mid 1800s• Moisson studied transition metal carbides in the late 1800s– Developed specialized electric arc furnace– Pioneer in SiC research (artificial diamond) • Reactive processing of ZrB2– Tucker and Moody, Proc. Chem. Soc. 17, 129 (1901).“Although many of the refractory materials displayed capabilities for leading-edge and nose applications, some development efforts would be required to produce satisfactory components from these materials”E.B. Mathauser, “Materials for Application to Manned Reentry Vehicles,” pp. 559-570 in U.S. Air Force and NASA Joint Conference on Lifting Hypervelocity and Reentry Vehicles, April 11-14, 1960.UHTC is a Recent Term • Terms from literature of the 1960s and 70s– Refractory transition metal borides– Oxidation resistant diboride materials– Hard metals– Ceramals“Thermal Protection Systems:  Report on the Aspects of Thermal Protection of Interest to NASA and the Related R&D Requirements” NASA Technical Memorandum X-650, 1962.Recommendation 12: “Studies on materials at extreme temperatures and establishment of thermal and other pertinent material properties”UHTC is a Recent Term• Term first used in the open literature in the late 1980s and early 90s– 1989:  AFRL report “Ultra-High Temperature Ceramic Composites by K. Vedula from CWRU– 1991: AFRL report  “Ultra-High Temperature Applications” by Mehrotra from Wright State Univ.– 1993:  “Ultra-High Temperature Assessment Study” by Katz, Kerans, et al.– 1994: NASA report “Ultra-High Temperature Ceramics” by D.J. Rasky and J.D. Bull– NSWC CrB2-NbB2 from NSWC 1997 E.L. Courtright, H.C. Graham, A.P. Katz, and R.J. Kerans, “Ultra-High Temperature Assessment Study-Ceramic Matrix Composites,” WL-TR-91-4061, September 1992.Historic Studies• Projects sponsored by Air Force Materials Lab– Avco and Arthur Little examined thermodynamics and kinetics– ManLabs et al. studied thermomechanical propertiesKaufman, Clougherty, Rhodes, Kalish, Tye, et al.– Aerojet focused on phase equilibriaRudy with Nowotny as a consultant• NASA– Nozzle materials in the 1950s– TPS materials• Russia– All aspects of borides and carbides– >2000 of publications by SamsonovImage from G.S. Upadhaya, “Professor Grigorii ValentinovichSamsonov:  The Complete Materials Scientist,” Science of Sintering, 40, 99-103 (2008).How Do We Define UHTCs?• Melting temperature– Melting temperature above some threshold– 3000°C is commonly cited• Use temperature– Can be used for extended times above some temperature– Extended use vs. short duration– SiC can be used up to 1650°C for short times• Chemistry– Strong covalent bonds, but mixed bond character– Brittle at room temperatureMelting TemperatureS.V. Ushakov and A. Navrotsky, “Experimental Approaches to Thermodynamics above 1500°C,” Journal of the American Ceramic Society in press, DOI: 10.1111/j.1551-2916.2012.05102.xUse TemperatureSubsonic /SupersonicFlightVehiclesTodayHypersonicFlight (Mach 4-5+)- Access to Space- Global ReachFutureSolidPropulsionMissilesRequires new materialswith >2000°C capabilityHypersonic AirbreathersBased on slides by M. Opeka, U.S. Naval Surface Warfare CenterChemistryResearch from the 1960s• Why diborides and carbides?• How were Zr and Hf compounds identified?• What was studied?– Thermochemical properties– Mechanical properties– Thermal properties– Oxidation and environmental studies– Phase equilibria• SummaryWhy Diborides and Carbides?• Oxides found to be unsuitable for these temperatures– Melting temperatures are lower than borides and carbides– Creep is an issue– Resistance to thermal shock is poor– Thermal conductivity is too low• Borides and carbides– Thermodynamically stable– Strong covalent bonding leads to higher strength– Strength is maintained at elevated temperatures– Bonding has metallic character– Thermal shock and creep resistance is higherWhy Diborides?• Thermodynamically stable– AFRL research focused on commercial materials that were further processed– Melted or zone refined using induction heating apparatus• Oxidation behavior– Carbides showed linear kinetics over wide temperature range– Borides had parabolic kinetics at some temperatures and were deemed more promisingL.A. McClaine, “Thermodynamic and Kinetic Studies for a Refractory Materials Program” ASD-TDR-62-204Densification Behavior• Army funded densification studies of B4C, SiC, TiC, and TiN– Pressures up to 120 ksior 850 MPa– Reactive hot pressing– Specimens were 1 inch in diameter• Reported microstructures, strength and hardnessD. Kalish, E.V. Clougherty, and J. Ryan, “Fabrication of Dense Fine Grained Ceramic Materials” AMRA CR 6 7-04(F)Why Zr and Hf Diborides?• Initial study focused on comparing borides and other materials• Part II compared different borides• Ranked oxidation behavior– HfB2 and ZrB2 best– Ta, Ti, and Nb compounds were inferior• Examined impact of metal to boron ratio on densification, oxidation, and physical properties• Temperatures up to 2300°C were needed for densificationL. Kaufman and E.V. Clougherty, “Investigation of Boride Compounds for Very High Temperature Applications” AFML-TR-68-190 Oxidation Behavior• Zr and Hf diborides were identified as the most promising– Lowest oxidation rates• SiC additions improved oxidation rate at intermediate temperatures– Protective SiO2scale• HfB2 was better thanZrB2E.V. Clougherty, R.L. Pober, and L. Kaufman, “Synthesis of Oxidation Resistant Metal DiborideComposites,” Transactions of the Metallurgical Society of AIME, 242(6) 1077-1082 (1968).Mechanical Properties• Strength tested up to 1800°C• Range of relative density values• ZrB2 and HfB2– Nominally pure– SiC additions– Carbon additions• Porosity reduces strength despite a decrease in grain size• SiC reduces grain growth• Carbon improves resistanceto crack propagation and reduceselastic modulusW.H. Rhodes, E.V. Clougherty, and D. Kalish “Research and Development of Oxidation-Resistant Diborides:  Mechanical Properties” AFML-TR-68-190 Part II, Vol IV. 50 ksi ≈ 350 MPaThermal Properties• Thermal conductivity measured 100°C to 1000°C by cut bar method• Thermal diffusivity measured 1000°C to 2000°C by laser flash• Also measured:– CTE– Total emittance 92 W/m•KZrB2– CP– ∆S and ∆H• Built unique equip-ment for their studiesE.V. Clougherty, K.E. Wilkes, and R.P. Tye, “Research and Development of Oxidation-Resistant Diborides:  Thermal, Physical, Electrical, and Optical Properties” AFML-TR-68-190 Part II, Vol V. 84 W/m•K75 W/m•KHigh Velocity Testing• Inductively heated furnaces (cold gas, hot wall)– Low velocity: 1 cm/sec, pO2 range 0.013 atm to 0.2 atm,1 atm total pressure.– High velocity:  100 m/sec, air• Goal was to “bridge the gap” between furnace and arc heater testing• Temperature gradientsimpacted results– Induction heating – Inverse T gradient due toinsulating oxide scaleL. Kaufman and H. Nesor “Stability Characterization of Refractory Materials Under High Velocity Atmospheric Flight Conditions” AFML-TR-69-84 Part II, Vol II. Phase Equilibria• Rudy designed equipment for ultra-high temperature studies– Pirani furnace for melting of refractory materials– Melting points, solidus studies E. Rudy and G. Progulski, “Ternary Phase Equilibria in Transition Metal-Boron-Carbon-Silicon Systems:  Part III, Vol II.  Special Test Procedures” AFRL-TR-65-2• Ta-Hf-C ternary system• No maximum in meltingtemperature between HfC and TaC!Phase EquilibriaE. Rudy, “Ternary Phase Equilibria in Transition Metal-Boron-Carbon-Silicon Systems:  Part II, Vol I.  Ta-Hf-C System” AFRL-TR-65-2Summary of Historic Studies• Detailed fundamental studies were conducted in the 1960s and 70s– AFRL-sponsored research in the U.S.– Samsonov and others in in the U.S.S.R.• Unique equipment was designed and built• Significant advances in fundamental science– Processing and densification– Oxidation– Mechanical behavior– Thermal properties– Phase equilibria and thermochemical propertiesWhat Drove The Resurgence?• Advanced aerospace vehicle concepts– Hypersonic aviation– Reusable atmospheric re-entry vehicles– Air-breathing hypersonic missile systems• Nuclear renaissance– Advanced reactor designs– Fuel cycles to minimize proliferation• Other niche applications– High temperature electrodes– Microelectronics– Molten metal handlingX-43B Hypersonic Concept Image Courtesy of NASA• Strengths have improved due to the ability to produce fine grained, dense ceramics– Historically 300-500 MPa• Monteverde, Sciti, et al. have used silicides as sintering aids– Hot pressing ~800 MPaStrength– Sintering >500 MPa• Chamberlain used attrition milling to reduce particle size– >1000 MPa at room temperature W.H. Rhodes, E.V. Clougherty, and D. Kalish “Research and Development of Oxidation-Resistant Diborides:  Mechanical Properties” AFML-TR-68-190 Part II, Vol IV.A. Balbo and D. Sciti, Mater. Sci. and Eng. A, 475 108-112 (2008)A. Bellosi, F. Monteverde, and D. Sciti, Int. J. Applied Ceram. Technol., 3(1) 32-40 (2006). >0.25wt% O<0.1wt% O• Nominally pure ZrB2– Strength proportional to inverse square root of grain size for dense ceramics• ZrB2-SiC ceramics– Thermal expansion mismatch Mechanical Behaviorresults in residual stresses– ZrB2 in tension– SiC particle size controls strength– Microcracking threshold for SiCparticle sizes around 12 µm J. Watts et al., J. Am. Ceram. Soc., 94(12) 4410-4418 (2011). 2 µm• Nominally pure ZrB2– Historically, relative density >98% not possible with grain size <50 µm– O impurities are critical– Pressureless sintering• ZrB2-SiC compositions– Historically, 2100°C or higherDensification– PS or HP at 1900°C– SPS at 1750°C or higher– Additives and particle sizeW.G. Fahrenholtz et al., J. Am. Ceram. Soc., 91(5) 1398-1404 (2008). OxidationZrB2-SiC with TaB2Solid = 1200°CDotted = 1400°C Dashed = 1500°C• Historic studies– Compared oxygen uptake, mass gain, and scale thickness• Modern studies– Mainly TGA studies and furnace oxidation at ≤1600°C– Modeling to understand mechanismsPeng et al., J. Mater. Res. 24(5) 1855-1867 (2009)Parthasarathay et al.,  Acta Mater, 55, 5999-6010 (2007)– Best performance with silica scale formers plus modifying additivesTesting• Historic studies– Compared oxygen uptake, mass gain, and scale thickness• Modern studies– Arc heater testing– Plasma wind tunnel reports by ISTEC– Torch tests and extreme temperatures from Harbin group– Laser melting by ImperialMonteverde and Savino, J. Am. Ceram. Soc., in pressJ. Han, Compos. Sci. Technol., 68, 799-806 (2008) Summary of Recent Progress• Interest in UHTCs grew in the 1990s– Hypersonics, re-entry, and propulsion• Mechanical behavior has been studied– Improved strength due to finer grain sizes– Strength-limiting features were identified• Densification behavior was improved– Control of surface oxide impurities and starting powder size• Oxidation and testing have continued– Modeling and additive studies– Relevant environment testingKey Issues for Implementation• Fabrication technologiesCan parts be made to near net shape at reasonable cost?• PropertiesIs behavior representative of inherent properties?• PerformanceImprovements needed in resistance to oxidation, thermal shock, thermal cycling, and creep Can we move from concept to an operational hypersonic flight vehicle?X-51 Concept Image Courtesy of NASA X-51 Test VehicleImage Courtesy of NASAThank you!TPS TypesAblativeReusable InsulationShock wave Blunt sampleSharp Leading Edge

Ultra-High Temperature Ceramics: Historic Perspectives and Recent Progress

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Ultra-High Temperature Ceramics: Historic Perspectives and Recent Progress

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