D B. Marshall, J.B. Davis Current Opinion in Solid State and Materials Science 5(2001)283-20 of High-Temperature Materials, New York: Oxford University YAG with fugitive carbon phase and with black glass matrix. Press,1999:229-243. La-hexaluminate coatings degrade tow strengths(40%) but help 140 Davis JB, Marshall DB, Oka Ks, Housley RH, MorgaN otect the fibers from reaction with the matrix. YAg coatings die Ceramic composites for thermal protection systems. Composites: Part A1999;30:483-8 [48] Boakye E, Hay RS, Petry MD, Parthasarathy TA. Sol-gel [*41 Davis JB, Marshall DB, Morgan PED, Oka Ks, Barney AO, thesis of zircon-carbon precursors and of Nextel Hogenson PA. Damage tolerant thermal protection systems, in 720TM fiber tows. Ceram Eng Sci Proc 65-72,A Proc Space 2000, American Institute of Aeronautics and As- ircon-carbon precursor was continuously tronautics, Long Beach, CA, 2000. Infiltration and heat treatmen 720TM fibers using a sol-gel method. Zircon formation was f fiber tows and fabrics with monazite slurries and solution tarded by the presence of carbon. recursors. Strength degradation observed for solution precursor [49 Keller KA, Mah Tl, Parthasarathy TA et al. Fugitive interfacial atings for oxide/oxide composites. J Am Ceram Soc arries of monazite powder, giving 53: 329-36, Comparison of effect of interface gap in com monazite matrix. Retained strengths =: with dense and porous matrices [50] Peters PWM, Daniels B, Clemens F et al. Mechanical characteri- 442] Boakye E, Hay RS, Petry MD Continuous coating of oxide fiber ation of mullite-based ceramic matrix composites at test tem tows using liquid precursors: monazite coatings on Nextel 720. J up to 1200C. J Eur Ceram Soc 2000: 20: 53 1-5, Nextel 610 Ceram Soc 1999: 82- 2321-31. Seven different fibre-reinforced mullite-based matrix with a 0. 1-Hm thick carbon ethanolic precursors were used to coat monazite on Nextel 720 oating on fibers. Tensile strength decreased rapidly at tempera- fiber tows using the immiscible liquid displacement method to minimize bridging of coating between filaments. Coatings were [ Halverson HG, Curtin WA pture of Nextel 610/alumina cured in-line at 1200-1400C. Tensile strengths measured from yttria composites. Ceram Eng Sci Proc 2000: 21:559-66, HT individual coated fibers showed significant degradation. strength, stress-rupture, and creep of composite with porous [] Hay Rs, Boakye E, Petry MD. Effect of coating deposition natrix/interface: large decreases in rupture stress at 1050"C mperature on monazite coated fiber. J Eur Ceram Soc [52] Mackin TJ, Roberts MC. Evaluation of damage evolution in 2000: 20: 589-97, Further studies as in previous reference and ceramic-matrix composites using thermoelastic stress analysis microstructural analysis. Tensile strengths of coated fibers de Am Ceram Soc 2000: 83: 337-43, Thermoelastic stress analysis creased with increasing deposition temperature and with time at from several composites, including Al, O3 /Al,O,(c-coating on temperature after deposition. Possible reasons for the strength fibers). The Al, O, /AL,O, composite showed notch insensitivity decrease are discussed milar to other composites. [*44] Boakye EE, Petry MD, Hay RS, Douglas LM. Monazite coatings [53 Cinibulk MK. Hexaluminates as a cleavable fiber-matrix inter on Nextel 720, 610, and Tyranno-SA fiber tows: effects of phase: synthesis, texture development, and phase compatibility, J recursors on fiber strength. Ceram Eng Sci Proc 2000: 21: 229- Eur Cer Soc 2000: 20: 569-82, Review of current state of research Further studies previous two references, with three on hexaluminate as a potential cleavable oxide fiber-matrix ifferent precursors and curing in-line at temperatures betweer 900 and 1300C. Fibers with coatings formed from colloidal 54] Cinibulk MK. Effect of divalent cations on the synthesis of rhabdophane particles showed higher strengths than ed citrate-gel-derived lanthanum hexaluminate powders and films. J fibers after 100 h at 1200C. Discussion of potential Mater Res 1999; 14: 3581-93, Achieved improved [0001] texture gaseous species and coating porosity of thin films. However, degree of basal texture achieved at 145 Holmquist M, Lundberg R, Sudre O, Razzell AG, Molliex L, sufficiently low temp to coat polycrystalline fibers is very lot Benoit J, Adlerborn J Alumina/alumina composite with a porous [55] Callender RL, Barron AR. Facile synthesis of aluminum irconia interphase ocessing,properties and componen taining mixed metal oxides doped carboxylate-alumoxane testing. J Eur Ceram Soc 2000: 20: 599-606, Composite consisting nanoparticles. J Am Ceram Soc 2000: 83: 1777-89 of sapphire fibers with porous zirconia coating in an alumina 56 Callender RL, Barron AR. A new route to hexaluminate ceramics matrix. Moderate strength(100-130 MPa), but retained compo- via a novel transmetalation reaction. Ceram Eng Sci Proc site properties at high temperatures and after aging(1000 h at 1999;20:27-34 1400C). Combustor tiles were manufactured and successfully [57] Saruhan B, Schneider H, Komarneni S, Abothu IR. Electro- tested in a rig at temperatures>1260.C and up to 46 cycles statically deposited surface seeding and promotion of allia. [46] Holmquist M, Adlerborn J, Razzell T, Sudre O, Molliex L tion of sol-gel derived La All1018 coating on oxide J EL Processing and properties of oxide matrix/oxide fibre composite Ceram Soc1999;192427-35 Br Ceram Trans 2000- 99: 266-9 [58] Hay RS, Hermes EE. Sol-gel coatings on continuous ceramic [47] Cinibulk MK, Parthasarathy TA, Keller KA, Mah T-l. Porous fibers. Ceram Eng Sci Proc 1990, 11: 1526-38 are-earth aluminate fiber coatings for oxide-oxide composites. 59] Kerans RJ, Hay RS. Parthasarathy TA. Structural ceramic cor Ceram Eng Sci Proc 2000: 21: 219-28, Strengths of tows and posites. Current Opinion in Solid State Materials Science inicomposites with porous coatings of La-hexaluminate and 99;4:45-51D.B. Marshall, J.B. Davis / Current Opinion in Solid State and Materials Science 5 (2001) 283–289 289 of High-Temperature Materials, New York: Oxford University YAG with fugitive carbon phase and with black glass matrix. Press, 1999: 229–243. La-hexaluminate coatings degrade tow strengths (40%) but help [40] Davis JB, Marshall DB, Oka KS, Housley RH, Morgan PED. protect the fibers from reaction with the matrix. YAG coatings did Ceramic composites for thermal protection systems. Composites: not degrade the tow strengths. Part A 1999;30:483–8. [48] Boakye E, Hay RS, Petry MD, Parthasarathy TA. Sol–gel [**41] Davis JB, Marshall DB, Morgan PED, Oka KS, Barney AO, synthesis of zircon-carbon precursors and coatings of Nextel Hogenson PA. Damage tolerant thermal protection systems, in: 720TM fiber tows. Ceram Eng Sci Proc 1999;20:165–72, A Proc Space 2000, American Institute of Aeronautics and As- zircon–carbon precursor was continuously coated on Nextel tronautics, Long Beach, CA, 2000. Infiltration and heat treatment 720TM fibers using a sol–gel method. Zircon formation was of fiber tows and fabrics with monazite slurries and solution retarded by the presence of carbon. precursors. Strength degradation observed for solution precursors. [*49] Keller KA, Mah TI, Parthasarathy TA et al. Fugitive interfacial Highest strengths were achieved by infiltration with aqueous carbon coatings for oxide/oxide composites. J Am Ceram Soc slurries of monazite powder, giving composites with a porous 2000;83:329–36, Comparison of effect of interface gap in com￾monazite matrix. Retained strengths higher than uncoated control posites with dense and porous matrices. specimen [50] Peters PWM, Daniels B, Clemens F et al. Mechanical characteri- [**42] Boakye E, Hay RS, Petry MD. Continuous coating of oxide fiber sation of mullite-based ceramic matrix composites at test tempera￾tows using liquid precursors: monazite coatings on Nextel 720. J tures up to 12008C. J Eur Ceram Soc 2000;20:531–5, Nextel 610 Am Ceram Soc 1999;82:2321–31, Seven different aqueous or fibre-reinforced mullite-based matrix with a 0.1-mm thick carbon ethanolic precursors were used to coat monazite on Nextel 720 coating on fibers. Tensile strength decreased rapidly at tempera- fiber tows using the immiscible liquid displacement method to tures above 8008C. minimize bridging of coating between filaments. Coatings were [51] Halverson HG, Curtin WA. Stress-rupture of Nextel 610/alumina cured in-line at 1200–14008C. Tensile strengths measured from yttria composites. Ceram Eng Sci Proc 2000;21:559–66, HT individual coated fibers showed significant degradation. strength, stress-rupture, and creep of composite with porous [*43] Hay RS, Boakye E, Petry MD. Effect of coating deposition matrix/interface: large decreases in rupture stress at 10508C. temperature on monazite coated fiber. J Eur Ceram Soc [52] Mackin TJ, Roberts MC. Evaluation of damage evolution in 2000;20:589–97, Further studies as in previous reference and ceramic-matrix composites using thermoelastic stress analysis. J microstructural analysis. Tensile strengths of coated fibers de- Am Ceram Soc 2000;83:337–43, Thermoelastic stress analysis creased with increasing deposition temperature and with time at from several composites, including Al O /Al O (c-coating on 23 23 temperature after deposition. Possible reasons for the strength fibers). The Al O /Al O composite showed notch insensitivity 23 23 decrease are discussed. similar to other composites. [**44] Boakye EE, Petry MD, Hay RS, Douglas LM. Monazite coatings [*53] Cinibulk MK. Hexaluminates as a cleavable fiber-matrix inter￾on Nextel 720, 610, and Tyranno-SA fibert tows: effects of phase: synthesis, texture development, and phase compatibility. J precursors on fiber strength. Ceram Eng Sci Proc 2000;21:229– Eur Cer Soc 2000;20:569–82, Review of current state of research 36, Further studies as in previous two references, with three on hexaluminates as a potential cleavable oxide fiber-matrix different precursors and curing in-line at temperatures between interphase. 900 and 13008C. Fibers with coatings formed from colloidal [54] Cinibulk MK. Effect of divalent cations on the synthesis of rhabdophane particles showed higher strengths than uncoated citrate-gel-derived lanthanum hexaluminate powders and films. J fibers after 100 h at 12008C. Discussion of potential effects of Mater Res 1999;14:3581–93, Achieved improved [0001] texture gaseous species and coating porosity. of thin films. However, degree of basal texture achieved at [*45] Holmquist M, Lundberg R, Sudre O, Razzell AG, Molliex L, sufficiently low temp to coat polycrystalline fibers is very low. Benoit J, Adlerborn J. Alumina/alumina composite with a porous [55] Callender RL, Barron AR. Facile synthesis of aluminum con￾zirconia interphase — processing, properties and component taining mixed metal oxides using doped carboxylate-alumoxane testing. J Eur Ceram Soc 2000;20:599–606, Composite consisting nanoparticles. J Am Ceram Soc 2000;83:1777–89. of sapphire fibers with porous zirconia coating in an alumina [56] Callender RL, Barron AR. A new route to hexaluminate ceramics matrix. Moderate strength (100–130 MPa), but retained compo- via a novel transmetalation reaction. Ceram Eng Sci Proc site properties at high temperatures and after aging (1000 h at 1999;20:27–34. 14008C). Combustor tiles were manufactured and successfully [57] Saruhan B, Schneider H, Komarneni S, Abothu IR. Electro￾tested in a rig at temperatures.12608C and up to 46 cycles. statically deposited surface seeding and promotion of crystalliza- [46] Holmquist M, Adlerborn J, Razzell T, Sudre O, Molliex L. tion of sol–gel derived La Al11018 coating on oxide fibers. J Eur Processing and properties of oxide matrix/oxide fibre composite. Ceram Soc 1999;19:2427–35. Br Ceram Trans 2000;99:266–9. [58] Hay RS, Hermes EE. Sol–gel coatings on continuous ceramic [47] Cinibulk MK, Parthasarathy TA, Keller KA, Mah T-I. Porous fibers. Ceram Eng Sci Proc 1990;11:1526–38. rare-earth aluminate fiber coatings for oxide-oxide composites. [59] Kerans RJ, Hay RS. Parthasarathy TA. Structural ceramic com￾Ceram Eng Sci Proc 2000;21:219–28, Strengths of tows and posites. Current Opinion in Solid State & Materials Science minicomposites with porous coatings of La-hexaluminate and 1999;4:445–51