CERAMICS INTERNATIONAL ELSEVIER Ceramics International 32(2006)613-616 Fabrication and interfacial structure of AlO3/Ni laminar ceramics Kai Hui zuo, Dong Liang Jiang", Qing Ling Lin The State Key Laboratory of High Performance Ceramics and Superfine Structure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, PR Chin Received 3 March 2005: received in revised form 12 March 2005: accepted 23 April 2005 Abstract AlO, /Ni laminar ceramic composite was fabricated by aqueous tape casting with close control of the thickness of Al2O3 and nickel layers Owing to a high flexibility and strength, green tapes of Al2O3 and Ni could be laminated easily at room temperature. The compact, defect free interfacial structures of Al,, /Ni laminar composites sintered by hot-pressing(HP) at 1400"C were investigated by X-ray diffraction(XRD) and energy dispersive X-ray analysis (EDX). It is shown that the diffusion of Al and Ni caused a progressive boundary between Al2O3 and Ni layers. The Al,O/Ni laminar composite was mostly composed of Al,O3 and Ni phases, together with a small amount of MgAl2, Al,Ni3 and NiAl1oO16 phases C 2005 Elsevier Ltd and Techna Group S.r.l. All rights reserved Keywords: A. Tape casting: B. Interfaces; C. Diffusion; D. Al2O3 1. Introduction electrophoresis deposition(EPD)[10-12], tape casting [6] plasma spraying [13], electroless plating, etc Although ceramics with high strength are good structural We tried using aqueous tape casting to produce nickel materials, the lack of damage tolerance ability constrains thin layers and Al2O3 thick layers. Al203/Ni laminate their application From a biomimetic point view, laminated materials were obtained by hot-pressing(HP)sintering composites have an advantage of insensitivity to defects. technology. The diffusion of interfacial elements and the Clegg and co-workers [1-4] had produced laminated Sic interfacial structure were investigated by X-ray diffraction ith graphite interface layers, which composite showed (XRD) and EDX stepped stress-strain behavior with higher apparent tough ness and work of fracture than monolithic Sic. The ceramic/ metal composite as a part of laminated composites 2. Experimental procedure ombines some advantages of the ceramics and metals. When crack stretches to the metal interlayer, due the Aqueous tape casting of Al2O3 and Ni was used to produce ductility of the metal, they can be deflected, bridged, etc. green tapes due to environmental and health considerations which behaviors generally improve the toughness of the The composition of the high solid(56. 4 wt%)alumina tape asting slurry is given in Table 1. Ni electrolytic powders Thick layers of laminar ceramic composites are usually (dso=265 um, Shanghai Jiuling Smelting Co Ltd, China) prepared by tape casting /5, 6), slip casting [7], centrifugal with amido, fatty acid and alcohol group show good casting[8]and self-propagating high temperature synthesis [1]. Thin layers can be realized by screen printing [9], dispersion and plasticity in the Pva water solution [14, 15]. Thus, Ni tap Corresponding author. Tel. +86 21 5241 2606: fax: +86 21 5241 3903 Tape casting was performed on Procast Precision Tape E-mail address: dujiang@ sum. shcnc ac cn(D.L. Jiang) Casting Equipment (Division of the International Inc 0272-8842/$30.00 2005 Elsevier Ltd and Techna Group S.r.L. All rights reserved doi:10.1016 j ceramist.2005.04027
Fabrication and interfacial structure of Al2O3/Ni laminar ceramics Kai Hui Zuo, Dong Liang Jiang *, Qing Ling Lin The State Key Laboratory of High Performance Ceramics and Superfine Structure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, PR China Received 3 March 2005; received in revised form 12 March 2005; accepted 23 April 2005 Available online 25 July 2005 Abstract Al2O3/Ni laminar ceramic composite was fabricated by aqueous tape casting with close control of the thickness of Al2O3 and nickel layers. Owing to a high flexibility and strength, green tapes of Al2O3 and Ni could be laminated easily at room temperature. The compact, defect free interfacial structures of Al2O3/Ni laminar composites sintered by hot-pressing (HP) at 1400 8C were investigated by X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX). It is shown that the diffusion of Al and Ni caused a progressive boundary between Al2O3 and Ni layers. The Al2O3/Ni laminar composite was mostly composed of Al2O3 and Ni phases, together with a small amount of MgAl2O4, Al4Ni3 and NiAl10O16 phases. # 2005 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Keywords: A. Tape casting; B. Interfaces; C. Diffusion; D. Al2O3 1. Introduction Although ceramics with high strength are good structural materials, the lack of damage tolerance ability constrains their application. From a biomimetic point view, laminated composites have an advantage of insensitivity to defects. Clegg and co-workers [1–4] had produced laminated SiC with graphite interface layers, which composite showed stepped stress–strain behavior with higher apparent toughness and work of fracture than monolithic SiC. The ceramic/ metal composite as a part of laminated composites combines some advantages of the ceramics and metals. When crack stretches to the metal interlayer, due the ductility of the metal, they can be deflected, bridged, etc. which behaviors generally improve the toughness of the composition. Thick layers of laminar ceramic composites are usually prepared by tape casting [5,6], slip casting [7], centrifugal casting [8] and self-propagating high temperature synthesis [1]. Thin layers can be realized by screen printing [9], electrophoresis deposition (EPD) [10–12], tape casting [6], plasma spraying [13], electroless plating, etc. We tried using aqueous tape casting to produce nickel thin layers and Al2O3 thick layers. Al2O3/Ni laminate materials were obtained by hot-pressing (HP) sintering technology. The diffusion of interfacial elements and the interfacial structure were investigated by X-ray diffraction (XRD) and EDX. 2. Experimental procedure Aqueous tape casting of Al2O3 and Ni was used to produce green tapes due to environmental and health considerations. The composition of the high solid (56.4 wt%) alumina tape casting slurry is given in Table 1. Ni electrolytic powders (d50 = 26.5 mm, Shanghai Jiuling Smelting Co. Ltd., China) with amido, fatty acid and alcohol group show good dispersiton and plasticity in the PVA water solution [14,15]. Thus, Ni tape casting slurry was composed by Ni electrolytic powder, water and PVA. Tape casting was performed on Procast Precision Tape Casting Equipment (Division of the International Inc., www.elsevier.com/locate/ceramint Ceramics International 32 (2006) 613–616 * Corresponding author. Tel.: +86 21 5241 2606; fax: +86 21 5241 3903. E-mail address: dljiang@sunm.shcnc.ac.cn (D.L. Jiang). 0272-8842/$30.00 # 2005 Elsevier Ltd and Techna Group S.r.l. All rights reserved. doi:10.1016/j.ceramint.2005.04.027
614 K H. Zuo et al. /Ceramics International 32(2006)613-616 Table 1 Composition of the alumina tape casting slurry Function Shanghai Wusong Fertilizer Factory, China Home- made Kalium polyacrylate(Lopon 895) Dispersant Bk giulini chemic representative office Meo Sintering assistant Shanghai Chemical Reagent Corp, China PVA Binder Shanghai Chemical Reagent Corp, China 1,2-C3HgO2 Shanghai Chemical Reagent Corp, China Ringoes, New Jersey) with a blade height of 200-500 um AlO AL2O3/Ni laminar composites were fabricated by periodi cally stacking Al2O3 and Ni layers(Fig. 1). Every layer Fig. 1. Schematic illustration of the Al2O3/Ni laminate contained some green films of Al2O3 or Ni. Subsequently, JEOL SEI 20. 0kV JE0LsE↓20,0k 180108m地 Fig. 2. SEM micrographs of Al2O3 and Ni green films after binder removal (left upper: optical graphs of Al2O3 and Ni green films) COMPO 100kv X300 10um Fig 3. SEM micrographs of the Al2O,/Ni interface (right is the magnified view of a small area from the left image)
Ringoes, New Jersey) with a blade height of 200–500 mm. Al2O3/Ni laminar composites were fabricated by periodically stacking Al2O3 and Ni layers (Fig. 1). Every layer contained some green films of Al2O3 or Ni. Subsequently, 614 K.H. Zuo et al. / Ceramics International 32 (2006) 613–616 Table 1 Composition of the alumina tape casting slurry Ingredient Function Manufacture Al2O3 (d50 = 0.6 mm) Ceramic powder Shanghai Wusong Fertilizer Factory, China Deionized water Solvent Home-made Kalium polyacrylate (Lopon 895) Dispersant Bk guiulini chemic representative office MgO Sintering assistant Shanghai Chemical Reagent Corp., China PVA Binder Shanghai Chemical Reagent Corp., China 1,2-C3H8O2 Plasticizer Shanghai Chemical Reagent Corp., China Fig. 2. SEM micrographs of Al2O3 and Ni green films after binder removal (left upper: optical graphs of Al2O3 and Ni green films). Fig. 3. SEM micrographs of the Al2O3/Ni interface (right is the magnified view of a small area from the left image). Fig. 1. Schematic illustration of the Al2O3/Ni laminate
K H. Zuo et al. /Ceramics International 32(2006)613-616 615 organic additives were removed at 800C for 2 h in a vacuum drying oven. Then ntered by hot pressing at 25 MPa under an argon atmosphere at 1400C for I h Surface properties and microstructure characterizations of Al2O3 and Ni green films were measured by optical microscopy(Olympus BX5IM, Japan) and by SEM JSM- 6700F, Japan). Energy dispersive X-ray analysis(EDX, EPMA-8705QH2) was performed across the interface order to determine the diffusion of elements from adjacent layers. The crystal structure was obtained from X-ray diffraction(Rigaku D/max 2550VX, Cu Ka) 3. Results and discussion Fig. 4. Element analysis from a scan through an interface of the Al2o,/Ni laminar compos The qualities of green film, such as homogeneity, surface quality, absence of bubbles and cracks greatly affect the graphs of Al2O3 and Ni green films and SEM micrographs a similar gradually varying trend, suggesting some diffusion after binder removal are given in Fig. 2. Films do not present of Al and Ni species. Based on estimation, the diffusion bubbles and cracks(left upper graphs of Fig. 2). The dark distance of Ni in Al2O3 layer is about 10-25 um. The areas in SEM micrographs are holes formed during the diffusion distance of Al is longer than the length of Ni layer rganic matter removal, especially PvA. The homogeneous(Fig. 3)and the distribution of Al in Ni layer is not distribution of holes indicates the homogeneity of the green homogenous. The reason is the lower solid content of Ni film. These films have very good strength and flexibility, and green film. After binder removal, holes in Ni film form the can be easily cut and stacked together route for al diffusion SEM micrographs of interfaces between Al2O3 and Ni XRD analysis(Fig. 5)was used to detect compounds in layers are shown in Fig 3. The grey area is Al,O3 and the the Al2O3/Ni laminar composites. In order to detect the dark area is Ni. Al2O3 and Ni layers are all compact without different compounds with changing the thickness ratio of Ni/ delamination and voids. However, it is difficult to detect Al2O3 layer, samples from Al2O3/Ni-1# to Al,O/Ni-4# with exactly the boundary between the Al2O3 and Ni layer from decreasing thickness ratio were used. The Al2 O3/Ni lamina the left graph of Fig 3, which is the magnified view of a composite is mostly composed of Al2O3 and Ni phases, small area from the right image. This might be due to the together with little MgAl2O4, Al4Ni3 and NiAl1oO16 phases diffusion of elements This result confirms the diffusion of al and ni elements To observe clearly the diffusion phenomena, sampl And contents of Ni compounds decreasing from Al2O3/Ni with the thicker of Ni interlayer were characterized by EDX, 1# to Al2O3/Ni-4# indicate that the element diffusion benefit as shown in fig 4. Al and ni elements diffusion lines exhibit from a thicker Ni interlayer. AIONi-4#. ALO /Ni-3# ⊥⊥。Ld O ALO A|.ON-2# Igel ☆NA|O Al ON-1#i Al, o3 Fig. 5. XRD analysis of Al2O/Ni laminar structures
organic additives were removed at 800 8C for 2 h in a vacuum drying oven. Then Al2O3/Ni laminates were sintered by hot pressing at 25 MPa under an argon atmosphere at 1400 8C for 1 h. Surface properties and microstructure characterizations of Al2O3 and Ni green films were measured by optical microscopy (Olympus BX51M, Japan) and by SEM JSM- 6700F, Japan). Energy dispersive X-ray analysis (EDX, EPMA-8705QH2) was performed across the interface in order to determine the diffusion of elements from adjacent layers. The crystal structure was obtained from X-ray diffraction (Rigaku D/max 2550 V X, Cu Ka). 3. Results and discussion The qualities of green film, such as homogeneity, surface quality, absence of bubbles and cracks greatly affect the properties of Al2O3/Ni laminar compositions. Optical graphs of Al2O3 and Ni green films and SEM micrographs after binder removal are given in Fig. 2. Films do not present bubbles and cracks (left upper graphs of Fig. 2). The dark areas in SEM micrographs are holes formed during the organic matter removal, especially PVA. The homogeneous distribution of holes indicates the homogeneity of the green film. These films have very good strength and flexibility, and can be easily cut and stacked together. SEM micrographs of interfaces between Al2O3 and Ni layers are shown in Fig. 3. The grey area is Al2O3 and the dark area is Ni. Al2O3 and Ni layers are all compact without delamination and voids. However, it is difficult to detect exactly the boundary between the Al2O3 and Ni layer from the left graph of Fig. 3, which is the magnified view of a small area from the right image. This might be due to the diffusion of elements. To observe clearly the diffusion phenomena, samples with the thicker of Ni interlayer were characterized by EDX, as shown in Fig. 4. Al and Ni elements diffusion lines exhibit a similar gradually varying trend, suggesting some diffusion of Al and Ni species. Based on estimation, the diffusion distance of Ni in Al2O3 layer is about 10–25 mm. The diffusion distance of Al is longer than the length of Ni layer (Fig. 3) and the distribution of Al in Ni layer is not homogenous. The reason is the lower solid content of Ni green film. After binder removal, holes in Ni film form the route for Al diffusion. XRD analysis (Fig. 5) was used to detect compounds in the Al2O3/Ni laminar composites. In order to detect the different compounds with changing the thickness ratio of Ni/ Al2O3 layer, samples from Al2O3/Ni-1# to Al2O3/Ni-4# with decreasing thickness ratio were used. The Al2O3/Ni laminar composite is mostly composed of Al2O3 and Ni phases, together with little MgAl2O4, Al4Ni3 and NiAl10O16 phases. This result confirms the diffusion of Al and Ni elements. And contents of Ni compounds decreasing from Al2O3/Ni- 1# to Al2O3/Ni-4# indicate that the element diffusion benefit from a thicker Ni interlayer. K.H. Zuo et al. / Ceramics International 32 (2006) 613–616 615 Fig. 4. Element analysis from a scan through an interface of the Al2O3/Ni laminar composite. Fig. 5. XRD analysis of Al2O3/Ni laminar structures
K H. Zuo et al. /Ceramics International 32(2006)613-616 4. Conclusions 4]AJ. Phillipps, W.J. Clegg, T w. Clyne, The correlation of interfacial d acroscopic toughness in SiC laminates, Composites 24(2)(1993) 17 Tape casting is a useful technique in fabricating laminar 5] K.s. Blanks, A. Kristoffersson, E. Carlstrom, wJ. Clegg. Crack ceramic composites with close control of the thickness of deflection in ceramic laminates using porous interlayers, J. Eur. green film. Green films exhibit good qualities, such as Ceram.Soc.18(13)(1998)1945-195 homogeneity of composition, smooth surface, being free from bubbles and cracks, and so on. The interface bonding of [6]ZChen,JJ.Mecholskym, Toughening by 76(5)(1993)1258- the Al2O3/Ni laminar composite seems almost macro defect [7 J. Requena, R. Moreno, J.S. Moya, Alumina and alumina/zirconia free. Al and Ni elements diffuse near the boundary region layer composites obtained by slip casting, J. Am. Ceram Soc. 72 forming an interphase area composed of Al2O3, Ni, (8)(1989)1511-1513 MgAl2O4, AlANi3, NiAl1oO16 phases D B. Marshall, J.J. Ratto, F.F. Lange. Enhanced fracture toughness in yered microcomposites of Ce-zrO2 and Al2O3. J. Am. Ceram Soc. 74(12)(1991)2979-2987 Acknowledgment [9] T.X. Liang, J.G. Zhu, B. Yang. B.Z. Zhang, X.L. Peng, Sintering esses in co-sintered AIN/w multilayer substrates. J. Chin. Ceram. Soc.26(3)(1998)286-291 This work is supported by the Science and Technology [10] P. Sarkar, P.S. Nicholson, Electrophoretic deposition(EPD):mechan- ommittee of Shanghai Municipal under the project No ism, kinetics and application to ceramics, J. Am. Ceram. Soc. 79(8 02DJ14065 and by Chinese Academy of Science under the (1996)1987-2002 project No. ICGCX2-Sw-602-3 [11 o.O. Van der Biest, LJ. Vandeperre, Electrophoretic deposition of materials, Annu. Rev. Mater. Sci. 29(1999)327-352. [12] C. You, D L. Jiang, S.H. Tan, SiC/TiC laminated structure haped by elec-trophoretic deposition, Ceram. Int. 30(5)(2004) References 813-815 [13] J.L. He, W.Z. Li, H D. Li, C.H. Liu, Plastic properties of nano-scale [1] wJ. Clegg K. Kendall, N M. Alford, T W. Button, J.D. Birchall,A eramic-metal multilayers, Surf. Coat. Technol. 103-104(1998)276- 455-457 [14 R Moreno. The role of slip additives in tape-casting technology Part l. vents and dispersants. Am. Ceram Soc. Bull. 71(10)(1992)1521- 3] A.J. Phillipps, w.J. Clegg. T.w. Clyne, Fracture behavior of cer [15]R. Moreno, The role of slip additives in tape-casting technology. Part laminates in bending. L. modeling of crack propagation, Acta Metall I. Binders and plasticizers, Am. Ceram Soc. Bull. 71(11)(1992) Mater.41(3)(1993)805-817 1647-1657
4. Conclusions Tape casting is a useful technique in fabricating laminar ceramic composites with close control of the thickness of green film. Green films exhibit good qualities, such as homogeneity of composition, smooth surface, being free from bubbles and cracks, and so on. The interface bonding of the Al2O3/Ni laminar composite seems almost macro defect free. Al and Ni elements diffuse near the boundary region, forming an interphase area composed of Al2O3, Ni, MgAl2O4, Al4Ni3, NiAl10O16 phases. Acknowledgment This work is supported by the Science and Technology Committee of Shanghai Municipal under the project No. 02DJ14065 and by Chinese Academy of Science under the project No. ICGCX2-SW-602-3. References [1] W.J. Clegg, K. Kendall, N.M. Alford, T.W. Button, J.D. Birchall, A simple way to make tough ceramics, Nature (London) 347 (4) (1990) 455–457. [2] W.J. Clegg, The fabrication and failure of laminar ceramic composites, Acta Metall. Mater. 40 (11) (1992) 3085–3093. [3] A.J. Phillipps, W.J. Clegg, T.W. Clyne, Fracture behavior of ceramic laminates in bending. I. modeling of crack propagation, Acta Metall. Mater. 41 (3) (1993) 805–817. [4] A.J. Phillipps, W.J. Clegg, T.W. Clyne, The correlation of interfacial and acroscopic toughness in SiC laminates, Composites 24 (2) (1993) 166–176. [5] K.S. Blanks, A. Kristoffersson, E. Carlstrom, W.J. Clegg, Crack deflection in ceramic laminates using porous interlayers, J. Eur. Ceram. Soc. 18 (13) (1998) 1945–1951. [6] Z. Chen, J.J. Mecholskym, Toughening by metallic lamina in nickel/ alumina composites, J. Am. Ceram. Soc. 76 (5) (1993) 1258– 1264. [7] J. Requena, R. Moreno, J.S. Moya, Alumina and alumina/zirconia multilayer composites obtained by slip casting, J. Am. Ceram. Soc. 72 (8) (1989) 1511–1513. [8] D.B. Marshall, J.J. Ratto, F.F. Lange, Enhanced fracture toughness in layered microcomposites of Ce-ZrO2 and Al2O3, J. Am. Ceram. Soc. 74 (12) (1991) 2979–2987. [9] T.X. Liang, J.G. Zhu, B. Yang, B.Z. Zhang, X.L. Peng, Sintering stresses in co-sintered AlN/W multilayer substrates, J. Chin. Ceram. Soc. 26 (3) (1998) 286–291. [10] P. Sarkar, P.S. Nicholson, Electrophoretic deposition (EPD): mechanism, kinetics and application to ceramics, J. Am. Ceram. Soc. 79 (8) (1996) 1987–2002. [11] O.O. Van der Biest, L.J. Vandeperre, Electrophoretic deposition of materials, Annu. Rev. Mater. Sci. 29 (1999) 327–352. [12] C. You, D.L. Jiang, S.H. Tan, SiC/TiC laminated structure shaped by elec-trophoretic deposition, Ceram. Int. 30 (5) (2004) 813–815. [13] J.L. He, W.Z. Li, H.D. Li, C.H. Liu, Plastic properties of nano-scale eramic-metal multilayers, Surf. Coat. Technol. 103–104 (1998) 276– 280. [14] R. Moreno, The role of slip additives in tape-casting technology. Part I. Solvents and dispersants, Am. Ceram. Soc. Bull. 71 (10) (1992) 1521– 1531. [15] R. Moreno, The role of slip additives in tape-casting technology. Part II. Binders and plasticizers, Am. Ceram. Soc. Bull. 71 (11) (1992) 1647–1657. 616 K.H. Zuo et al. / Ceramics International 32 (2006) 613–616