Tape-cast alumina-zirconia laminates: processing and mechanical properties K1c(MPavm) K1c(MPavm FIRST SERIES (SENB) SECOND SERIES ICNI AZ5IAZ5 AZ10/A210 AZ10JAZ5 AAZ10/A210757 15/32/2210/2/2/2 Fig9. Fracture toughness of the diffcrent grades(a)SENB rcsults from Rcf. 2.(b )CN results(cross-head speed=0-01 mm min ') cast materials. The slurry formulation was opti- mized in order to tape cast defect-free samples 80 with a high green density and a good thermocom pression ability 四m5 2/2/2/10/2/2/2 370 360 3/15/ R eferences 350 Hill bounds 340Az10 Amateau, M. F.& Messing, G. L, Laminated ceramic omposites. In international Encyclopedia of Composite 2. Chartier, T, Besson, J. L.& Boch, P, Mechanical prop- 320 erties of ZrO -Al,O, laminated composites. In Advance E ics, Science and Technology of Zirconia Ill. E vol. 24, eds S. Somiya, N. Yamamoto& H. Yanagida m. Ceram Soc., Westerville, Ohio, 1988, pp. I131-1138 3. Boch, P, Chartier, T& Huttepain, M, Tape casting of 00.1020.30.40.50.60.70.80.9 12OyZro, laminated composites, J. Am. Ceram. Soc. Fig. 10. Youngs moduli of the different laminates. The Hill 9(8)(1986)191-19 bounds were drawn for comparison. Voigt and Reuss's curves 4. Chartier, T.& Besson, J. L,, Behaviour of ZrOx-AlO3 are almost superposed due to rather close Young,'s moduli for laminated composites loaded by various A and AZIo rrangements. In Science of Ceramics, vol. 14. ed. D. Tay- lor. The Institute of Ceramics, UK, 1988, pp. 639-644 5. Russo. C.J. Harmer, M. P. Chan, h. M.& miller, G A. Design of laminated ceramic composite for improved composite than for the bulk components. This strength and toughness. J. Am. Ceram. Soc.. 75(12) remarkable improvement is assumed to be essen (1992)3963400 tially related to the presence of thermally induced 6. Harmer, M.P, Chan. H, M.& Miller, G. A, Unique pportunities for microstructural engineering with dupley residual stre which, according to a and laminar ceramic composites. J, Am. Cerum. Soc plane stress model, can be as high as 130 MPa 75(7)(1992)1715-1728 Crack deflection is essentially a consequence of 7. Plucknett. K. P. Caceres. C. H.& Wilkinson. D...Tape sting of fine alumina/zirconia powders for co the residual stresses fabrication, J. Am. Ceram. Soc., 77(8)(1994)2137-2144 Phosphate esters are highly effective dispersants 8. Plucknett, K. P,, Caceres, C. H, Hughes. C.& wilkin- for alumina in MEK/Etoh solvent but their on.D.S, Processing of tape-cast laminates prepared effectiveness is strongly dependent on their charac 77(8)(1994)2145-2153. Powders.J. Am. Ceran. Soc teristics. Four parameters were varied and an 9. Takebe H. Morinaga, K. Fabrication and mechanical improved phospha aving (i)an aliph properties of lamellar AlO3 ceramics. J, Ceram. Soc. Jpn molecule, (ii) a high diester concentration, (ii)a Inter.,96(1988)l122-1128 10. Chartier. T. Merle. D. Besson.I. I. I aminar ceramic high degree of phosphatization and (iv) a high composites. J. Eur. Ceram. Soc., 15(1995)101-10 Hydrophile/ Lypophile Balance was synthesized 11. Mistler, R. E, Shanefield, D. J.& Runk. R. B. Tape The organic components in a slurry play a sting of ceramics. In Ceramic Processing before Firing. ds g. Y. Onada L. L. Hench, John wiley Sons prominent role on the green properties of tape New York. 1978. 411-418Tape-cast alumina-zirconia laminates: processing and mechanical properties 301 Klc (MPa\Tm) Klc (MPaViE) 1 A A/A AZSIAZS AZlO/AZlO AZlOIAZS A A/A AZlO/AZlO 71517 311513 2/2/2/1oi2/2/ (4 04 Fig. 9. Fracture toughness of the different grades (a) SENB results from Ref. 2, (b) CN results (cross-head speed = 0.01 mm min ‘). 390 380 370 340 ( / dL_ 0 --IfQ %k ; 0 A/A 7/5/-l 4 A Hill bounds - AZ10 t 360 350 330 320 310 t 300”“““““““““’ 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 10. Young’s moduli of the different laminates. The Hill bounds were drawn for comparison. Voigt and Reuss’s curves are almost superposed due to rather close Young’s moduli for A and AZIO. composite than for the bulk components. This remarkable improvement is assumed to be essen￾tially related to the presence of thermally induced residual stresses which, according to a simple plane stress model, can be as high as 130 MPa. Crack deflection is essentially a consequence of the residual stresses. Phosphate esters are highly effective dispersants for alumina in MEIUEtOH solvent, but their effectiveness is strongly dependent on their charac￾teristics. Four parameters were varied and an improved phosphate ester having (i) an aliphatic molecule, (ii) a high diester concentration, (iii) a high degree of phosphatization and (iv) a high Hydrophile/Lypophile Balance was synthesized. The organic components in a slurry play a prominent role on the green properties of tape￾cast materials. The slurry formulation was opti￾mized in order to tape cast defect-free samples with a high green density and a good thermocom￾pression ability. References 1. 2. 3. 4. 5. 6. I. 8. 9. 10. 11. Amateau, M. F. & Messing, G. L., Laminated ceramic composites. In International Encyclopedia of Composites, vol. 3, ed. S. M. Lee. VCH New York, 1990, pp. 11-16. Chartier, T., Besson, J. L. & Both, P., Mechanical prop￾erties of Zr02-A120, laminated composites. In Advances in Ceramics, Science and Technology of Zirconia III, vol. 24, eds S. Somiya, N. Yamamoto & H. Yanagida. Am. Ceram. Sot., Westerville, Ohio, 1988, pp. 1131-l 138. Both, P., Chartier, T. & Huttepain, M., Tape casting of Al,O,/ZrO, laminated composites, J. Am. Ceram. Sot., 69(8) (1986) 191-192. Chartier, T. & Besson, J. L., Behaviour of ZrO?-A&O, laminated composites loaded by various mechanical arrangements. In Science of Ceramics, vol. 14, ed. D. Tay￾lor. The Institute of Ceramics, UK, 1988, pp. 639-644. Russo, C. J., Harmer, M. P., Chan, H. M. & Miller, G. A. Design of laminated ceramic composite for improved strength and toughness. J. Am. Ceram. Sot., 75( 12) ( 1992) 3396-3400. Harmer, M. P., Chan, H. M. & Miller, G. A.. Unique opportunities for microstructural engineering with duplex and laminar ceramic composites. J. Am. Ceram. Sot.. 75(7) (1992) 1715-1728. Plucknett, K. P., Caceres. C. H. & Wilkinson, D. S.. Tape casting of fine alumina/zirconia powders for composite fabrication. J. Am. Ceram. Sot., 77(8) (1994) 2137-2144. Plucknett, K. P., Caceres, C. H.. Hughes, C. & Wilkin￾son, D. S., Processing of tape-cast laminates prepared from fine alumina/zirconia powders. J. Am. Ceram. Sot., 77(8) (1994) 2145-2153. Takebe, H. & Morinaga, K., Fabrication and mechanical properties of lamellar A&O, ceramics. J. Ceram. Sac. Jpn Inter., 96 (1988) 1122-l 128. Chartier, T., Merle, D. & Besson, J. L., Laminar ceramic composites. J. Eur. Ceram. Sot., 15 (1995) 101-107. Mistler, R. E., Shanefield, D. J. & Runk, R. B., Tape casting of ceramics. In Ceramic Processing &fore Firing, eds G. Y. Onada & L. L. Hench, John Wiley & Sons, New York, 1978. 411418