A.R. Boccaccini, 1. Zhitomirsky/ Current Opinion in Solid State and Materials Science 6(2002)251-260 presented in Ref [50] where the fabrication of compos- ites of tubular shape is demonstrated. The EPD cell used is shown schematically in Fig. 2[50]. Major advances in this area are expected, in particular related to the furthe development of the EPD technique for the fabrication of oxide fibre-oxide matrix ceramic composites with high systems are those by Kooner et al. [51] and Manocha et al [48]. Efforts should however concentrate on the production of complex shape components, for which the EPD tech- nique may represent the most technically viable and cost effective option. 2. 6. Laminated and graded composites Fig. 1. SEM micrograph of EPD-infiltrated SiC (Nicalon")fibre mat using a mixed colloidal suspension of mullite composition. A high-level EPD has been used successfully to fabricate ceramic infiltration is seen which leads to porous-f laminated composites and graded materials. Developments opposites [44 up to 2000 are covered in Ref [**3]. Recent advances in functionally graded materials(FGM) have been reported by Put et al. [52, 53. They manufactured graded wC-Co fibre preforms are now quite well composites using a suspension of wc powder in acetone understood The pH of the solution, the applied with variable Co powder content. In another significant voltage and deposition time are shown to have a strong development by the same group, anodic co-deposition of ence on the quality of the infiltration. Good particle Al,O3 and CeO, -stabilised zirconia powders was used to packing and a high solids-loading can be achieved, produc- obtain cylindrical and tubular-shaped Al, O, /zirconia ing firm ceramic deposits which adhered to the fibres, thus FGM components [*54] leading to pore-free composites after a post-EPD heat- Current efforts are devoted to the development of EPD treatment process. The typical microstructure of a mullite fabrication approaches for laminated ceramic composites, matrix composite reinforced by SiC (Nicalon ) fibres in particular in the system zirconia/alumina, due to the fabricated by EPD is shown in Fig. I high fracture resistance of these structures [55-57. The Most previous research summarized in Ref. [**44] has significance of the papers by Moreno and Ferrari [56] and been focused on components of simple planar shape. The by Uchikoshi et al. [571, is that they focus on optimized use of EPD for near-net shape fabrication of 3-D compo- aqueous suspensions, which should be always preferred ite components of complex shapes is starting to be over organic suspensions due to environmental and econ- investigated. A pioneering development in this area is omic considerations. Based on the promising results balance woven fibre mat in tube form as deposition electrode(-)d. c. central electrode+dc outer electrode(+)d.c boehmite(r-AlOOHD) sol glass container Fig. 2. Schema of the EPD cell recently introduced for the fabrication of tubular metal fibre reinforced alumina matrix composites [ 50](diagram courtesy Dr C Kaya, University of Birmingham, UK)254 A.R. Boccaccini, I. Zhitomirsky / Current Opinion in Solid State and Materials Science 6 (2002) 251–260 presented in Ref. [*50], where the fabrication of compos￾ites of tubular shape is demonstrated. The EPD cell used is shown schematically in Fig. 2 [*50]. Major advances in this area are expected, in particular related to the further development of the EPD technique for the fabrication of oxide fibre-oxide matrix ceramic composites with high oxidation resistance. Recent promising results in these systems are those by Kooner et al. [51] and Manocha et al. [48]. Efforts should however concentrate on the production of complex shape components, for which the EPD tech￾nique may represent the most technically viable and cost￾effective option. 2 .6. Laminated and graded composites  Fig. 1. SEM micrograph of EPD-infiltrated SiC (Nicalon ) fibre mat EPD has been used successfully to fabricate ceramic using a mixed colloidal suspension of mullite composition. A high-level of ceramic infiltration is seen which leads to porous-free ceramic laminated composites and graded materials. Developments composites [**44]. up to 2000 are covered in Ref. [**3]. Recent advances in functionally graded materials (FGM) have been reported by Put et al. [52,53]. They manufactured graded WC–Co infiltration of the fibre preforms are now quite well composites using a suspension of WC powder in acetone understood [**44]. The pH of the solution, the applied with variable Co powder content. In another significant voltage and deposition time are shown to have a strong development by the same group, anodic co-deposition of influence on the quality of the infiltration. Good particle Al O and CeO -stabilised zirconia powders was used to 23 2 packing and a high solids-loading can be achieved, produc- obtain cylindrical and tubular-shaped Al O /zirconia 2 3 ing firm ceramic deposits which adhered to the fibres, thus FGM components [*54]. leading to pore-free composites after a post-EPD heat- Current efforts are devoted to the development of EPD treatment process. The typical microstructure of a mullite fabrication approaches for laminated ceramic composites,  matrix composite reinforced by SiC (Nicalon ) fibres in particular in the system zirconia/alumina, due to the fabricated by EPD is shown in Fig. 1. high fracture resistance of these structures [55–57]. The Most previous research summarized in Ref. [**44] has significance of the papers by Moreno and Ferrari [56] and been focused on components of simple planar shape. The by Uchikoshi et al. [57], is that they focus on optimized use of EPD for near-net shape fabrication of 3-D compo- aqueous suspensions, which should be always preferred site components of complex shapes is starting to be over organic suspensions due to environmental and econ￾investigated. A pioneering development in this area is omic considerations. Based on the promising results Fig. 2. Schema of the EPD cell recently introduced for the fabrication of tubular metal fibre reinforced alumina matrix composites [*50] (diagram courtesy Dr C. Kaya, University of Birmingham, UK)