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A.R. Boccaccini et al./Composites: Part A 32(2001)997-1006 5 vvvv 050 -10V 20V △仓白 Fig. 5. EPD of boehmite sols on to Ni-coated carbon fibre mats. Graphs of the(a)electrophoretic deposit weight and(b)electrophoretic deposit thickness, as a atmosphere for one day and left in normal air for another lomerates within the suspension. EPD experiments day before being pressureless sintered at 1250C for 2 h were carried out under vacuum in order to eliminate under nitrogen atmosphere. the undesirable formation and entrapment of bubbles To prepare green and sintered fibre reinforced ceramic within the deposit due to the electrolysis(evolution of matrix composite(CMC) samples for cross-sectional scan gases)of the aqueous sol dispersion medium. Under ning electron microscopy (SEM), the specimens were vacuum, very fine boehmite can penetrate placed in a vacuum chamber and vacuum-impregnated deep into the inter/intra-fibre filling all the with Epofix resin. Impregnated green and sintered CMC voids, resulting in the formation samples were left to harden overnight and then cut into green(and sintered) composites slices using a diamond saw. A high resolution scanning The graphs in Fig. 5(a) and(b) show the results of electron microscope ( Field Emission Gun, FEG SEM lectrophoretic deposit weight and thickness, respec Hitachi S4000, Japan) was employed to characterise the tively, as a function of deposition time for different various microstructural features of the infiltrated and applied voltages. EPD experiments were performed for intered composite bodies, including grain shape and size, up to 500 s, as this gave a deposit thickness of about porosity distribution and location, ductile interface, deposit 660 um which was enough to produce a composite with thickness and infiltration of the matrix into the fibre arch an acceptable green density. The deposit thickness tecture in both green and sintered samples increased with increasing deposition time. When aqueous-based sols are used in EPD experiments, one 3. 2. Evaluation of EPD experiments associated problem is the electrolysis of the water. Higher voltages resulted in rapid deposit formation, The boehmite sol used was kinetically stable and well but also in the undesirable formation and entrapment dispersed, as there were no big heteroflocculated of bubbles within the deposit due to the electrolysis ( 64A5 4 ( - 9 " : % & & "7!:% (( ((& ! + : ( ( ( "M ! 1( M!1 7!: 0 7&E555 @ % ( (( ( ( , ( ( 2 & ( 6939 2 2 =' - ( 2 .( ( !#$ ( ( (( ( ( ( "( % '(( ( (( I & ( &'( " % - M A"% "% ( 2 & ( !#$ ( A55 2 ( BB5 ( ( - 2 K '((& ( !#$ 0 ( ( ( ( ( -9(9 1 9 : )' 8 - 63 *3 + !!;< 655> M A !#$ / & 1 "% "% 2 (