Availableonlineatwww.sciencedirect.com DIRECT E≈RS ELSEVIER Journal of the European Ceramic Society 26(2006)1567-1576 www.elsevier.com/locate/jeurcera Fabrication technologies for oxide-oxide ceramic matrix composites based on electrophoretic deposition E. Stoll a P MahraH-G. Kruger aH. Kern a B.J. C. Thomas.AR. BoccacciniD,* a Institute of Materials Technology. Technical University of ILmenau. D-98684 Ilmenau, Germany b Department of Materials, Imperial College London, Prince Consort Road, London SW72BP. UK Received 29 November 2004: received in revised form 17 March 2005; accepted 19 March 2005 Available online 17 May 2005 Abstract Electrophoretic deposition(EPD) was used to fabricate alumina matrix composites with high volume fraction of woven fibre mat(Nextel M 720)reinforcement in a multilayer structure. Colloidal suspensions of Al,O3 nanoparticles in ethanol medium with addition of 4-hydrobezoic acid were used for EPD. Two different techniques were developed for fabrication of Al2O3 matrix/Nextel TM 720 fibre composites. The first method is a combination of standard EPD of single fibre mats with a subsequent lamination procedure to fabricate the multilayered composite The second method involves the simultaneous infiltration of several( three or more)NextelTM 720 fibre mats by EPD in a tailor-made cell. The mposites exhibit a homogeneous matrix microstructure, characterised by a very high particle packing density and relatively low porosity after sintering at 1300C. The EPD cell allows production of relatively large bodies(10 cm diameter). By combination of the multilayer EPD infiltration and lamination processes developed here, thick ceramic matrix composite components(>10mm thickness)can be fabricated, which opens the possibility of greater industrial application of the materials o 2005 Elsevier Ltd. All rights reserved. Keywords: Suspensions; Composites; Al2O3; Electrophoretic deposition 1. Introduction and fibres 15,16 18-25 The main advantages of Epd over a con- ventional slurry route are the reduced processing times and Continuous fibre-reinforced oxide ceramic matrix com- improved control over green body microstructure. 5,6Aque- posites( CMCs) have attracted significant scientific and tech- ous or non-aqueous suspensions of ceramic(nano)particles nological interest for high temperature structural applications are usually considered for forming the matrix, and both con- in gas turbines, rocket engines, heat exchangers and hot fil- ductive(e.g SiC Nicalon, carbon) and non-conductive(e.g. ters, due to their low specific weight, damage-tolerant be NextelTM)fibres have been used as reinforcement. 8-25In haviour, oxidation resistance and high resistance to cree the case of non-conductive fibres, the fibre weave is placed in front of the deposition electrode and the ceramic deposit expended in the optimisation of CMCs, with particular em- forms on the electrode and grow around and through the fibre phasis on the establishment of reliable and cost effective fab- mat. 5.25 A schema of a typical EPD cell, commonly used for rication procedures. -14 the infiltration of single non-conductive fibre mats, is shown Electrophoretic deposition(EPD)is the process by which in Fig charged particles in a liquid medium move under an applied This paper presents EPD based methods for the fabrication potential towards an oppositely charged electrode and coagu of multilayer NextelTM 720 fibre-reinforced alumina matrix late there to form a stable deposit. -EPD has been used for composites. Two techniques are described, based or the production of CMCs with a variety of ceramic matrices Corresponding author. Tel. +44 207594 6731: fax: +44 20 7594675 (i)EPD of single NextelTM 720 fibre mats and subsequer E- Jmail address: a boccaccini@imperial ac uk(A R. Boccaccini lamination using Al2O3 paste to form the matrix and 0955-2219/S-see front matter 2005 Elsevier Ltd. All rights reserved. doi: 10. 1016/j-jeurceramsoc. 2005.03.251Journal of the European Ceramic Society 26 (2006) 1567–1576 Fabrication technologies for oxide–oxide ceramic matrix composites based on electrophoretic deposition E. Stoll a, P. Mahr a, H.-G. Kruger ¨ a, H. Kern a, B.J.C. Thomas b, A.R. Boccaccini b,∗ a Institute of Materials Technology, Technical University of Ilmenau, D-98684 Ilmenau, Germany b Department of Materials, Imperial College London, Prince Consort Road, London SW7 2BP, UK Received 29 November 2004; received in revised form 17 March 2005; accepted 19 March 2005 Available online 17 May 2005 Abstract Electrophoretic deposition (EPD) was used to fabricate alumina matrix composites with high volume fraction of woven fibre mat (NextelTM 720) reinforcement in a multilayer structure. Colloidal suspensions of Al2O3 nanoparticles in ethanol medium with addition of 4-hydrobezoic acid were used for EPD. Two different techniques were developed for fabrication of Al2O3 matrix/NextelTM 720 fibre composites. The first method is a combination of standard EPD of single fibre mats with a subsequent lamination procedure to fabricate the multilayered composite. The second method involves the simultaneous infiltration of several (three or more) NextelTM 720 fibre mats by EPD in a tailor-made cell. The composites exhibit a homogeneous matrix microstructure, characterised by a very high particle packing density and relatively low porosity after sintering at 1300 ◦C. The EPD cell allows production of relatively large bodies (10 cm diameter). By combination of the multilayer EPD infiltration and lamination processes developed here, thick ceramic matrix composite components (>10 mm thickness) can be fabricated, which opens the possibility of greater industrial application of the materials. © 2005 Elsevier Ltd. All rights reserved. Keywords: Suspensions; Composites; Al2O3; Electrophoretic deposition 1. Introduction Continuous fibre-reinforced oxide ceramic matrix com￾posites (CMCs) have attracted significant scientific and tech￾nological interest for high temperature structural applications in gas turbines, rocket engines, heat exchangers and hot fil￾ters, due to their low specific weight, damage-tolerant be￾haviour, oxidation resistance and high resistance to creep and thermal shock.1–6 Significant research effort is being expended in the optimisation of CMCs, with particular em￾phasis on the establishment of reliable and cost effective fab￾rication procedures.1–14 Electrophoretic deposition (EPD) is the process by which charged particles in a liquid medium move under an applied potential towards an oppositely charged electrode and coagu￾late there to form a stable deposit.15–17 EPD has been used for the production of CMCs with a variety of ceramic matrices ∗ Corresponding author. Tel.: +44 20 7594 6731; fax: +44 20 75946757. E-mail address: a.boccaccini@imperial.ac.uk (A.R. Boccaccini). and fibres.15,16,18–25 The main advantages of EPD over a con￾ventional slurry route are the reduced processing times and improved control over green body microstructure.15,16 Aque￾ous or non-aqueous suspensions of ceramic (nano)particles are usually considered for forming the matrix, and both con￾ductive (e.g. SiC Nicalon®, carbon) and non-conductive (e.g. NextelTM) fibres have been used as reinforcement.18–25 In the case of non-conductive fibres, the fibre weave is placed in front of the deposition electrode and the ceramic deposit forms on the electrode and grow around and through the fibre mat.15,25 A schema of a typical EPD cell, commonly used for the infiltration of single non-conductive fibre mats, is shown in Fig. 1. This paper presents EPD based methods for the fabrication of multilayer NextelTM 720 fibre-reinforced alumina matrix composites. Two techniques are described, based on: (i) EPD of single NextelTM 720 fibre mats and subsequent lamination using Al2O3 paste to form the matrix and 0955-2219/$ – see front matter © 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.jeurceramsoc.2005.03.251