L Ceseracciu et al. International Journal of Refractory Metals Hard Materials 23(2005)375-381 4. Conclusions References The alumina surface of Al O3/AlO3+ZrO, lami [1 Fischer-Cripps AC, Lawn BR. Stress analysis of contact nated structure exhibited an apparent fracture tough nation in quasi-plastic ceramics. J Am Ceram Soc 1996 less higher than that of monolithic alumina. Under the explored experimental conditions when this material 2]Moya JS. Layered ceramics. Adv Mater 1995: 7(2): 185-9 3] Harner MP, Chan HM, Miller GA. Unique opportunities for is subjected to cyclic loading, and the resultant surface microstructural engineering with duplex and laminar ceramic damaged produced is compared to a monolithic alumina composites. J Am Ceram Soc 1992: 75(7): 1715-28 with a similar microstructure, two different types of (4 Sanchez-Herencia AJ, James L, Lange FF. Bifurcation in alumina behaviour are observed depending on the number of cy plates produced by a phase transformation in central alumina zirconia thin layers. J Eur Ceram Soc 2000: 20(9): 1297-300 cles: At a low number of cycles, the a/AZ is more resis- 5 Chan HM. Layered ceramics: Processing and mechanical behav tant to the development of ring cracks than the MA r. Annu Rev Mater Sci 1997: 27: 249-82. At high numbers of cycles, a highly damaged surface [6] Mawdsley JR, Kovar D, Halloran JW. Fracture behaviour of appears in the A/AZ This difference is attributed to the enhanced fracture toughness of the A/AZ material, which implied [7 Marshall DB, Ratto JJ, Lange FF. Enhanced fracture toughness a higher resistance to ring and cone cracking. This layered microcomposites of Ce-ZrO2 and Al2O3. J Am Ceram enhanced apparent fracture toughness also implies a 8] Sorensen BF, Horsewell A. Crack growth along interfaces in higher tendency to shear microcracking, that is, to porous ceramic layers. J Am Ceram Soc 2001; 84(9): 2051-9 quasi-plasticity. At very high number of cycles, this [9] Requena J, Moreno R, Moya JS.Alumina and alumina/zirconia microcracking leads to material spallation at the contact 1989:72(8):151l-3 [10] Goretta KC, Gutierrez- Mora F, Picciolo JJ, Routbort JL Joining In previous works [12, 20] the difference in behaviour alumina/zirconia ceramics. Mater Sci Eng A 2003: 341: 158-62. (cone cracking vs quasi-plasticity) was studied as a fune [11]Toschi F, Melandri C, Pinasco P, Roncari E, Guicciardi S, De ion of grain size(which gives a change in toughness) Portu G. Influence of residual stress on the wear behaviour of alumina/alumina-zirconia laminated composites. J Am Ceram However in this study this difference is attributed solely Soc2003;86(9:1547-53 to the presence of residual stress, as microstructure of [12] Lee SK, Lawn BR. Contact fatigue in silicon nitride. J Am Ceram both laminates and monolithic material can be consid- Socl99982(5:128l-8. ered almost similar. This is a novel result that has to [13] Kim DK, Jung Y-G, Peterson IM, Lawn BR. Cyclic fatigue of be taken into account in designing laminated materials intrinsically brittle ceramics in contact with spheres. Acta Mater 999:47(18):4711-25 with residual stresses. Thus, although the A/az materia [14] Fett T, Keller R, Munz D, Ernst E, Thun G. Fatigue of alumina presents a better resistance to the development of dam- under contact loading. Eng Fract Mech 2003: 70: 1143-5 age at low and intermediate numbers of cycles, at high [15] Jimenez-Pique E, Ceseracciu L, Chalvet F, Anglada M, de portu numbers of cycles spallation of the material occurs, in Hertzian G. contact fatigue on alumina/alumina-zirconia lami stead of multiple cone cracking. It is then important nated composites. J Eur Ceram Soc, in press. [16] Fiori C, de Portu G. Tape casting: A technique for preparing and properly use these laminate materials in order to take studying new materials, In: Davidge RW, editor. British Ceramic dvantage in their contact resistance while avoiding sur Proccedings no. 38. Novel ceramic fabrication face chipping, specially if used in a application where tri- applications. Shelton, Stoke-on-Trent, UK, December 1986. p 213 bological and wear properties are important [17 Anstis GR, Chantikul P, Lawn BR. A critical evaluation of indentation techniques for measuring fracture toughness: I. Direct crack measurements. J Am Ceram Soc 1981: 64: 533-8. [18] Lawn BR. Indentation of ceramics with spheres: A century after Acknowledgement Hertz. J Am Ceram Soc 1998: 81(8): 1977-94. [19] Warren PD, Hills DA, Dal DN. Mechanics of Hertzian cracking. Tribol int1995;28(6):357-62. Work supported in part by the European Commu- [20] Rhee Y-W, Kim H-W, Deng Y, Lawn BR. Brittle fracture versus nity's Human Potential Programme under contract HPRN-CT-2002-00203, [SICMAC] and by the Spanish Ceram Soc200148(3):56l-5. Ministry of Science and Technology, through grant [21] Roberts sG, La Cw. Bisrat Y. Warren PD. Hills DA. MAT200200368 Determination of surface residual stresses in brittle materials by Hertzian indentation: Theory and experiment. J Am Ceram So L C. and F.C. acknowledge the financial provided through the European Communitys 2] Warren PD, Hills DA. The influence of elastic mismatch between Potential Programme under contract HPRN-C indenter and substrate on hertzian fracture. J Mater 00203 [SICMAC]. E.J.P. acknowledges the 2860-6. support provided by the Generalitat de Catalunya [23]Kara H, Roberts SG. Polishing behavior and surface quality of alumina and alumina/silicon carbide nanocomposites. JAm Grant RED-15/2002 Ceram Soc2000;83(5):1219-254. Conclusions The alumina surface of Al2O3/Al2O3 + ZrO2 lami￾nated structure exhibited an apparent fracture tough￾ness higher than that of monolithic alumina. Under the explored experimental conditions when this material is subjected to cyclic loading, and the resultant surface damaged produced is compared to a monolithic alumina with a similar microstructure, two different types of behaviour are observed depending on the number of cy￾cles: At a low number of cycles, the A/AZ is more resis￾tant to the development of ring cracks than the MA. At high numbers of cycles, a highly damaged surface appears in the A/AZ. This difference is attributed to the enhanced apparent fracture toughness of the A/AZ material, which implied a higher resistance to ring and cone cracking. This enhanced apparent fracture toughness also implies a higher tendency to shear microcracking, that is, to quasi-plasticity. At very high number of cycles, this microcracking leads to material spallation at the contact surface. In previous works [12,20] the difference in behaviour (cone cracking vs quasi-plasticity) was studied as a func￾tion of grain size (which gives a change in toughness). However in this study this difference is attributed solely to the presence of residual stress, as microstructure of both laminates and monolithic material can be consid￾ered almost similar. This is a novel result that has to be taken into account in designing laminated materials with residual stresses. Thus, although the A/AZ material presents a better resistance to the development of dam￾age at low and intermediate numbers of cycles, at high numbers of cycles spallation of the material occurs, in￾stead of multiple cone cracking. It is then important to properly use these laminate materials in order to take advantage in their contact resistance while avoiding sur￾face chipping, specially if used in a application where tri￾bological and wear properties are important. Acknowledgement Work supported in part by the European Commu￾nity
s Human Potential Programme under contract HPRN-CT-2002-00203, [SICMAC] and by the Spanish Ministry of Science and Technology, through grant MAT-2002-00368. L.C. and F.C. acknowledge the financial support provided through the European Community
s Human Potential Programme under contract HPRN-CT-2002- 00203 [SICMAC]. E.J.P. acknowledges the financial support provided by the Generalitat de Catalunya, Grant RED-15/2002. References [1] Fischer-Cripps AC, Lawn BR. Stress analysis of contact defor￾mation in quasi-plastic ceramics. J Am Ceram Soc 1996;79(10): 2609–18. [2] Moya JS. Layered ceramics. Adv Mater 1995;7(2):185–9. [3] Harner MP, Chan HM, Miller GA. Unique opportunities for microstructural engineering with duplex and laminar ceramic composites. J Am Ceram Soc 1992;75(7):1715–28. [4] Sa´nchez-Herencia AJ, James L, Lange FF. Bifurcation in alumina plates produced by a phase transformation in central alumina/ zirconia thin layers. J Eur Ceram Soc 2000;20(9):1297–300. [5] Chan HM. Layered ceramics: Processing and mechanical behav￾iour. Annu Rev Mater Sci 1997;27:249–82. [6] Mawdsley JR, Kovar D, Halloran JW. Fracture behaviour of alumina/monazite multilayer laminates. J Am Ceram Soc 2000; 83(4):802–8. [7] Marshall DB, Ratto JJ, Lange FF. Enhanced fracture toughness in layered microcomposites of Ce–ZrO2 and Al2O3. J Am Ceram Soc 1991;74(12):2979–87. [8] Sorensen BF, Horsewell A. Crack growth along interfaces in porous ceramic layers. J Am Ceram Soc 2001;84(9):2051–9. [9] Requena J, Moreno R, Moya JS. Alumina and alumina/zirconia multilayer composites obtained by slip casting. J Am Ceram Soc 1989;72(8):1511–3. [10] Goretta KC, Gutierrez-Mora F, Picciolo JJ, Routbort JL. Joining alumina/zirconia ceramics. Mater Sci Eng A 2003;341:158–62. [11] Toschi F, Melandri C, Pinasco P, Roncari E, Guicciardi S, De Portu G. Influence of residual stress on the wear behaviour of alumina/alumina–zirconia laminated composites. J Am Ceram Soc 2003;86(9):1547–53. [12] Lee SK, Lawn BR. Contact fatigue in silicon nitride. J Am Ceram Soc 1999;82(5):1281–8. [13] Kim DK, Jung Y-G, Peterson IM, Lawn BR. Cyclic fatigue of intrinsically brittle ceramics in contact with spheres. Acta Mater 1999;47(18):4711–25. [14] Fett T, Keller R, Munz D, Ernst E, Thun G. Fatigue of alumina under contact loading. Eng Fract Mech 2003;70:1143–52. [15] Jime´nez-Pique´ E, Ceseracciu L, Chalvet F, Anglada M, de Portu Hertzian G. contact fatigue on alumina/alumina-zirconia lami￾nated composites. J Eur Ceram Soc, in press. [16] Fiori C, de Portu G. Tape casting: A technique for preparing and studying new materials., In: Davidge RW, editor. British Ceramic Proccedings no. 38, Novel ceramic fabrication processes and applications. Shelton, Stoke-on-Trent, UK, December 1986. p. 213. [17] Anstis GR, Chantikul P, Lawn BR. A critical evaluation of indentation techniques for measuring fracture toughness: I. Direct crack measurements. J Am Ceram Soc 1981;64:533–8. [18] Lawn BR. Indentation of ceramics with spheres: A century after Hertz. J Am Ceram Soc 1998;81(8):1977–94. [19] Warren PD, Hills DA, Dal DN. Mechanics of Hertzian cracking. Tribol Int 1995;28(6):357–62. [20] Rhee Y-W, Kim H-W, Deng Y, Lawn BR. Brittle fracture versus quasi plasticity in ceramics: A simple predictive index. J Am Ceram Soc 2001;48(3):561–5. [21] Roberts SG, Lawrence CW, Bisrat Y, Warren PD, Hills DA. Determination of surface residual stresses in brittle materials by Hertzian indentation: Theory and experiment. J Am Ceram Soc 1999;82(7):1809–16. [22] Warren PD, Hills DA. The influence of elastic mismatch between indenter and substrate on Hertzian fracture. J Mater Sci 1994;23: 2860–6. [23] Kara H, Roberts SG. Polishing behavior and surface quality of alumina and alumina/silicon carbide nanocomposites. J Am Ceram Soc 2000;83(5):1219–25. L. Ceseracciu et al. / International Journal of Refractory Metals & Hard Materials 23 (2005) 375–381 381