H. Hadraba et al /Ceramics International 30 (2004)853-863 le-component deposits [11] e-FGM-transversal direction E00u29°-u VOLUME CONCENTRATION OF ZIRCONIA [ % Fig. 11. Dependence of fracture toughness of functionally gradient material FGM HP/Y-5 on zirconia volume concentration in depo the layers with predominant Al2O3 of higher green density Acknowledgements here appeared compression stresses that were closing the crack and this was reflected in the higher value of fracture This work was supported by the Czech Ministry of Edu toughne cation by the grant no. VZ CEZ: J22/98 4. Conclusion References Layered composite materials were prepared by alter- [M.P. Harmer, H.M. Chan, G.A. Miller, Unique opportunities for mi- lating deposition from isopropanol suspensions of Al2O3 structural engineering with duplex and laminar ceramic compos- and ZrO2 and subsequent sintering. The particles at the s,J.Am. Ceram.Soce.75(1992)1715-1728 layer interface were properly sintered and the layer inter- [2JE.M. Deliso, J. Kowalski, J.W.R. Cannon, Application of electroki- face did not contain an increased amount of pores. Thanks netic properties to the fabrication of an alumina-zirconia composite, Adv Ceram. Mater. 3(1988)407-410 to this strong bond between layers and thanks to residual [3]Z Wang, P. Xiao, J. Shemilt, Fabrication of composite coatings using stresses introduced into the material in the course of dry a combination of electrochemical methods and reaction bonding ing, sintering and cooling from the sintering temperature process, J. Eur. Ceram Soc. 20(2000)1469-1473 here occurred changes in the propagation of cracks in the []T. Uchikoshi, K. Ozawa, B D. Hatton, Y. Sakka, Dense, bubble-free composite, which makes the material interesting from the amic deposits from aqueous suspensions by electrophoretic depo- sition, J. Mater. Res. 16(2001)321-324. viewpoint of possible increase in fracture toughness and []B. Ferrari, A.J. Sanchez-Herencia, R. Moreno, Aqueous elec- strength trophoretic deposition of Al] O3/ZrO2 layered ceramics, Mater. Lett. Using electrophoretic deposition of a mixture of Al2O3 35(1998)370-374 and ZrO2 from isopropanol suspensions stabilized with [6]P Sarkar, X. Haung, P.S. Nicholson, Structural ceramic microlami- monochloroacetic acid it was possible to prepare particle ates by electrophoretic deposition, J. Am. Ceram. Soc. 75(1999) composite materials with a constant controlled Al2O3/Zro2 [7O. Prakash, P. Sarkar, P.S. Nicholson, Crack deflection in ce ratio. Thanks to the similar electrophoretic mobility of amic/ceramic laminates with strong interfaces, J. Am. Ceram. Soc. Al]O3 and Zro2 particles in the suspension the composite 78(1995)1125-1127 composition was constant throughout the whole deposit [8]B. Hatton, P.S. Nicholson, Design and fracture of layered volume Am. Ceram.Soc.84(2001)571-576 Functionally gradient materials with a smooth concentra [9]C. Hillman, Z Suo, F.E. Lange, Cracking of laminate tion transition from Al2O3 to ZrO2 were prepared by elec axial tensile stresses, J. Am. Ceram. Soc. 79(1996) 2133 trophoretic deposition of suspensions whose composition ihlarova, H. Hadraba, Influence of was changed in the course of deposition. The deposit com- electrophoretic behavior of alcoholic suspensions of alumina and position copied the suspension composition and the deposi zirconia, submitted for publicatio [11]K Ma Hadraba, J. Cihlar, Electrophoretic deposition of alumina tion kinetics corresponded to the theoretical models derived d zirconia-l. Sing ponent systems, Ceram. Int. 30(2004) for one-component deposits862 H. Hadraba et al. / Ceramics International 30 (2004) 853–863 Fig. 11. Dependence of fracture toughness of functionally gradient material FGM HP/3Y-5 on zirconia volume concentration in deposit. the layers with predominant Al2O3 of higher green density there appeared compression stresses that were closing the crack and this was reflected in the higher value of fracture toughness. 4. Conclusion Layered composite materials were prepared by alter￾nating deposition from isopropanol suspensions of Al2O3 and ZrO2 and subsequent sintering. The particles at the layer interface were properly sintered and the layer inter￾face did not contain an increased amount of pores. Thanks to this strong bond between layers and thanks to residual stresses introduced into the material in the course of dry￾ing, sintering and cooling from the sintering temperature, there occurred changes in the propagation of cracks in the composite, which makes the material interesting from the viewpoint of possible increase in fracture toughness and strength. Using electrophoretic deposition of a mixture of Al2O3 and ZrO2 from isopropanol suspensions stabilized with monochloroacetic acid it was possible to prepare particle composite materials with a constant controlled Al2O3/ZrO2 ratio. Thanks to the similar electrophoretic mobility of Al2O3 and ZrO2 particles in the suspension the composite composition was constant throughout the whole deposit volume. Functionally gradient materials with a smooth concentra￾tion transition from Al2O3 to ZrO2 were prepared by elec￾trophoretic deposition of suspensions whose composition was changed in the course of deposition. The deposit com￾position copied the suspension composition and the deposi￾tion kinetics corresponded to the theoretical models derived for one-component deposits. Acknowledgements This work was supported by the Czech Ministry of Edu￾cation by the grant no. VZ CEZ: J22/98. References [1] M.P. Harmer, H.M. Chan, G.A. Miller, Unique opportunities for mi￾crostructural engineering with duplex and laminar ceramic compos￾ites, J. Am. Ceram. Soc. 75 (1992) 1715–1728. [2] E.M. Deliso, J. Kowalski, J.W.R. Cannon, Application of electroki￾netic properties to the fabrication of an alumina–zirconia composite, Adv. Ceram. Mater. 3 (1988) 407–410. [3] Z. Wang, P. Xiao, J. Shemilt, Fabrication of composite coatings using a combination of electrochemical methods and reaction bonding process, J. Eur. Ceram. Soc. 20 (2000) 1469–1473. [4] T. Uchikoshi, K. Ozawa, B.D. Hatton, Y. Sakka, Dense, bubble-free ceramic deposits from aqueous suspensions by electrophoretic depo￾sition, J. Mater. Res. 16 (2001) 321–324. [5] B. Ferrari, A.J. Sánchez-Herencia, R. Moreno, Aqueous elec￾trophoretic deposition of Al2O3/ZrO2 layered ceramics, Mater. Lett. 35 (1998) 370–374. [6] P. Sarkar, X. Haung, P.S. Nicholson, Structural ceramic microlami￾nates by electrophoretic deposition, J. Am. Ceram. Soc. 75 (1999) 2907–2909. [7] O. Prakash, P. Sarkar, P.S. Nicholson, Crack deflection in ce￾ramic/ceramic laminates with strong interfaces, J. Am. Ceram. Soc. 78 (1995) 1125–1127. [8] B. Hatton, P.S. Nicholson, Design and fracture of layered Al2O3/TZ3Y composites produced by electrophoretic deposition, J. Am. Ceram. Soc. 84 (2001) 571–576. [9] C. Hillman, Z. Suo, F.F. Lange, Cracking of laminates subjected to biaxial tensile stresses, J. Am. Ceram. Soc. 79 (1996) 2127–2133. [10] J. Cihlar, Z. Cihlarova, H. Hadraba, Influence of weak acids on electrophoretic behavior of alcoholic suspensions of alumina and zirconia, submitted for publication. [11] K. Maca, H. Hadraba, J. Cihlar, Electrophoretic deposition of alumina and zirconia—I. Single-component systems, Ceram. Int. 30 (2004) 843–851