J. Am. Ceram. Soc., 90 [8 2657 DO:10.1111551-2916 c The American Ceramic Society journal Fabrication of Fiber- Reinforced Ceramic Composites by the modified Slurry Infiltration Technique Sea-Hoon Lee, Markus Weinmann, and Fritz Aldinger Max-Planck-Institut fur Metallforschung and Institut fur Nichtmetallische Anorganische Materialien, Universitat Stuttgart, Pulvermetallurgisches Laboratorium, D-70569 Stuttgart, Germany A new technique for the homogeneous infiltration of concentrat- sant. The 5 potential of SiC suspensions containing 1. 3 wt% ed and viscous ceramic filler slurries into stacked 2D-woven PEI was monitored using a E potential probe(Zetamaster, Mal fabrics has been developed by introducing a flexible mold. The vern Instrument Ltd, Malvern, U. K ) and the influence of the inner space of the mold expanded during slurry infiltra h value in the range of 6.5-9.3 on the viscosity of the slurrie hich enhanced penetration of the viscous slurry into the woven 30 vol% SiC, 1.5 wt% PED was determined using a viscometer fabric layers. The subsequent precursor impregnation and (SR-500, Rheometric Scientific, Piscatay pyrolysis process yielded fiber-reinforced ceramic composites For infiltration, 12 layers of 2D-woven carbon fabrics(T300 with scarce macropores between the fabric layers 3K, Toray, Tokyo, Japan) coated with a pyrocarbon were tacked in the conventional press casting or the modified de- form casting mold. The size of the stacked fabrics was 35 mm x 35 mm x 6 mm. Aqueous SiC slurries containing 30, 33 37,40,43,or45vol%SiC RECURSOR impregnation and pyrolysis(PIP) has been inves- uated mold by using an Ar gas pressure of 0. 125 MPa(absolute tigated as a low-temperature technique for the fabrication of pressure). After the infiltration, external pressure was applied to geneous infiltration of highly concentrated slurries into stacked the deform casting mold by tightening screws to squeeze excess woven fabrics is still a challenging research topic in terms of the and dried at so C for 24 h to remove entrapped gas and woven fabrics is frequently not completely filled by the filler dispersoid, respectively. Subsequently, the molds were vacu- material. During the fatigue testing, the large pores(so-called um-dried at 350C/0. 1 Pa to remove residual moisture from he compact before the impregnation of the liquid precursor romoting fatigue damage of FRC. The theoretical density of the Cfiber-Sicfiller compact In the present paper, we report on a technique for the prep- (Pcompact) was calculated by using the following equation: aration of FRC with minimized macro-inter-yarn porosity by Pcarbon +Isic. Psic(pearl making use of a deformable injection mold. The new processin 3.22g/cm3) he volume fraction of carbon(carbon)and Sic allows for an efficient infiltration of highly concentrated Si (Isic) was obtained from their volume, which was a quotient of lurries into stacked woven fabrics the weight of each component divided by its theoretical density The true density of the compact was estimated by dimensional II. Experimental Procedure The processing conditions and properties of the FRC are de- bed elsewhere in detail. I The microstructure of the FrC was Figure I displays schemes of the conventional vacuum/pressure analyzed with scanning electron casting(termed press casting) and the modified process termed 6400, Tokyo, Japan) deform casting. Infiltration of the aqueous slurry containing Sic particles(A-10, H. C. Starck, Goslar, Germany, irregular shape, dso: 0.51 um, oxygen content: 0.9 wt%)into the stacked II Results and discussion woven fabrics was mainly performed by applied pressure and capillary force. The uniqueness of the modified technique is the (1) SiC Slurries application of a mold with a deformable foil at the bottom The free space in the stacked woven fiber fabrics, which should A mold equipped with a polytetrafluoroethylene foil(Ado Sci- be filled with a precursor-derived ceramic matrix by repeated ence, Tokyo, Japan, thickness: 0.2 mm, commercial name: PIP processes, can be reduced by introducing filler materials and Teflon) was used in order to allow infiltration of a liquid by increasing the packing density of the filler materials. The polysilazane (VL20, polysilazane, KION, Huntingdon valley. preparation of highly concentrated slurries is a reasonable ap- PA)and subsequent thermal cross-linking. roach for this purpose slurries was adjusted by using polyethyleneimine(PEl, ati Aqueous Sic slurries have been reported to exhibit high To improve the infiltration further, the rhec eology of the Mw: 25000, Aldrich Chemical Co., Milwaukee, WI)as a dis slurries are not desirable because of the chemical reaction be tween the base and the precursor. Consequently, a dispersant A. Bandyopadhyay-contributing editor was applied to adjust the ph value of the slurry near 7. PEl was selected as the dispersant. The isoelectric point of aqueous Sic slurry has been reported in the literature to be near pH 2.Ob- viously, PEl shifts this value to pH9.8 by the protonation of the Manuscript No 22694 Received January 16, 2007: approved April 18, 2007. amine group in the molecule. The maximum 5 potential (36 Author to whom correspondence should be addressed. e-mail: mV) was attained at pH 6 'Present address: Composite Material Group, National Institute for Materials Science, Table I presents data on about the effect of ph on the vis- osity of 30 vol% slurries containing 1.5 wt% PEL. The lowest 2657
Fabrication of Fiber-Reinforced Ceramic Composites by the Modified Slurry Infiltration Technique Sea-Hoon Lee,w,z Markus Weinmann, and Fritz Aldinger Max-Planck-Institut fu¨r Metallforschung and Institut fu¨r Nichtmetallische Anorganische Materialien, Universita¨t Stuttgart, Pulvermetallurgisches Laboratorium, D-70569 Stuttgart, Germany A new technique for the homogeneous infiltration of concentrated and viscous ceramic filler slurries into stacked 2D-woven fabrics has been developed by introducing a flexible mold. The inner space of the mold expanded during slurry infiltration, which enhanced penetration of the viscous slurry into the woven fabric layers. The subsequent precursor impregnation and pyrolysis process yielded fiber-reinforced ceramic composites with scarce macropores between the fabric layers. I. Introduction PRECURSOR impregnation and pyrolysis (PIP) has been investigated as a low-temperature technique for the fabrication of fiber-reinforced ceramic matrix composites (FRC).1 The homogeneous infiltration of highly concentrated slurries into stacked woven fabrics is still a challenging research topic in terms of the PIP technique.2,3 The large free space between the individual woven fabrics is frequently not completely filled by the filler material. During the fatigue testing, the large pores (so-called macro-inter-yarn porosity) enhance the crack initiation, thus promoting fatigue damage of FRC.4,5 In the present paper, we report on a technique for the preparation of FRC with minimized macro-inter-yarn porosity by making use of a deformable injection mold. The new processing allows for an efficient infiltration of highly concentrated SiC slurries into stacked woven fabrics. II. Experimental Procedure Figure 1 displays schemes of the conventional vacuum/pressure casting (termed press casting) and the modified process termed deform casting.6 Infiltration of the aqueous slurry containing SiC particles (A-10, H. C. Starck, Goslar, Germany, irregular shape, d50: 0.51 mm, oxygen content: 0.9 wt%) into the stacked woven fabrics was mainly performed by applied pressure and capillary force. The uniqueness of the modified technique is the application of a mold with a deformable foil at the bottom. A mold equipped with a polytetrafluoroethylene foil (Ado Science, Tokyo, Japan, thickness: 0.2 mm, commercial name: Teflon) was used in order to allow infiltration of a liquid polysilazane (VL20, polysilazane, KION, Huntingdon Valley, PA) and subsequent thermal cross-linking. To improve the infiltration further, the rheology of the slurries was adjusted by using polyethyleneimine (PEI, Mw: B25 000, Aldrich Chemical Co., Milwaukee, WI) as a dispersant.7 The x potential of SiC suspensions containing 1.3 wt% PEI was monitored using a x potential probe (Zetamaster, Malvern Instrument Ltd., Malvern, U.K.), and the influence of the pH value in the range of 6.5–9.3 on the viscosity of the slurries (30 vol% SiC, 1.5 wt% PEI) was determined using a viscometer (SR-500, Rheometric Scientific, Piscataway, NJ). For infiltration, 12 layers of 2D-woven carbon fabrics (T300J 3K, Toray, Tokyo, Japan) coated with a pyrocarbon were stacked in the conventional press casting or the modified deform casting mold.8 The size of the stacked fabrics was 35 mm 35 mm 6 mm. Aqueous SiC slurries containing 30, 33, 35, 37, 40, 43, or 45 vol% SiC were introduced into the evacuated mold by using an Ar gas pressure of 0.125 MPa (absolute pressure). After the infiltration, external pressure was applied to the deform casting mold by tightening screws to squeeze excess slurry (Fig. 1(f)). After infiltration, the molds were evacuated and dried at 801C for 24 h to remove entrapped gas and dispersoid, respectively. Subsequently, the molds were vacuum-dried at 3501C/0.1 Pa to remove residual moisture from the compact before the impregnation of the liquid precursor. The theoretical density of the CfiberSiCfiller compact (rcompact) was calculated by using the following equation: rcompact5 tcarbon rcarbon1tSiC rSiC (rcarbon 5 1.81 g/cm3 , rSiC 5 3.22 g/cm3 ).8–10 The volume fraction of carbon (tcarbon) and SiC (tSiC) was obtained from their volume, which was a quotient of the weight of each component divided by its theoretical density. The true density of the compact was estimated by dimensional measurement. The processing conditions and properties of the FRC are described elsewhere in detail.11 The microstructure of the FRC was analyzed with scanning electron microscopy (SEM, JEOL, JSM- 6400, Tokyo, Japan). III. Results and Discussion (1) SiC Slurries The free space in the stacked woven fiber fabrics, which should be filled with a precursor-derived ceramic matrix by repeated PIP processes, can be reduced by introducing filler materials and by increasing the packing density of the filler materials. The preparation of highly concentrated slurries is a reasonable approach for this purpose. Aqueous SiC slurries have been reported to exhibit high negative x potentials at high pH values.12 However, strong alkaline slurries are not desirable because of the chemical reaction between the base and the precursor.13 Consequently, a dispersant was applied to adjust the pH value of the slurry near 7. PEI was selected as the dispersant. The isoelectric point of aqueous SiC slurry has been reported in the literature to be near pH 2.14 Obviously, PEI shifts this value to pH 9.8 by the protonation of the amine group in the molecule.15 The maximum x potential (36 mV) was attained at pH 6.5. Table I presents data on about the effect of pH on the viscosity of 30 vol% slurries containing 1.5 wt% PEI. The lowest A. Bandyopadhyay—contributing editor w Author to whom correspondence should be addressed. e-mail: LEE.Seahoon@ nims.go.jp z Present address: Composite Material Group, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan. Manuscript No. 22694. Received January 16, 2007; approved April 18, 2007. Journal J. Am. Ceram. Soc., 90 [8] 2657–2660 (2007) DOI: 10.1111/j.1551-2916.2007.01795.x r 2007 The American Ceramic Society 2657
2658 Commmunications of the American Ceramic Society Vol. 90. No. 8 Pressed fiber bundles Macro pore near the Infiltrated between mold woven fabrics between fabrics Deformable foi back of acked fabrics Reduction of△P Deformation of foil enlargement of macro Fiber bundles Relaxed fiber bundles slurry Residual slurry Enlargement of gap between fabric QOooooe ●●●●●● thickne Fig. 1. S ted pressure casting and a new deform casting process.(a, b) Conventional fixture of a firm Mold with a deformable foil during initial infiltration. The fabrics are pressed by the difference ssure(AP)inside and outside of the mold (d)Onset of outward deformation of the foil by the slurry(e)Completion of the foil deformation and infiltration of the slurry. (f)Removal of excess slurry by squeezing the mold viscosity was attained at pH 6.5, whereas this value increased in where h is the distance of liquid introduced within a period I alkaline slurries. Based on these results, the ph of the aqueous K the permeability of the porous body, n the viscosity of liquid (2) Slurry Infiltration K= m Lange et al. reported that the infiltration of dry, porous medi (2) um with slurry occurs by capillary force and applied pressure. The applied pressure enhances the infiltration into rather large where is the pore fraction, m the mean hydraulic radius (pore ces(Fig. 1). The capillary force becomes important as the size fraction divided by the wetted surface area), and ko of capillary decreases, e.g., at the free space between the indi- The above formulae inform that the viscosity of slurry and vidual fibers size art rtant factors for infiltration The flow of liquid into a porous medium by differential pres- Figure 2 shows the relative density of CiberSi Ciller compacts sure AP is described by Darcy's law with increasing solid loading of the infiltrated slurries. when sing conventional press casting, relative density of the com- 2K△P pacts decreases from 62% to 49%. This is a consequence of the ncomplete infiltration of the slurry(Fig 3), which became more obvious with increasing the solid loading of the slurry. After drying, the compacts infiltrated with 37 vol% slurry were Table 1. Viscosity(Pa s)of 30 Vol% SiC Slurries(+1.5 demolded, and were split into 12 layers. The infiltration oc- Wt% PED)at Varying pH Values curred both at the center and side of the fabrics. The slurry reached to the fourth layer from the side of the stack, but could Shear rates(s-) not penetrate the third layer to the middle area. Infiltration pH 6.5 0.155 3.4 x 10-2 1.1x10-2 of the central area of the stacked fabrics was therefore the bot 1.2x10-2 tleneck during press casting(Fig 3(2) pH8.3 5.1×10-2 15×10-2 At the onset of infiltration, part of the slurry migrated into pH 9.3 0.301 59×10-2 1. x 10-2 the largest gap, i. e, between the stacked fabrics and the mold (Fig. 1). When the fabrics are subjected to compression during mold closing, the pores and gaps between the fibers, the tows
viscosity was attained at pH 6.5, whereas this value increased in alkaline slurries. Based on these results, the pH of the aqueous SiC/PEI slurries was adjusted to this value before infiltration. (2) Slurry Infiltration Lange et al. 1 reported that the infiltration of dry, porous medium with slurry occurs by capillary force and applied pressure. The applied pressure enhances the infiltration into rather large spaces (Fig. 1). The capillary force becomes important as the size of capillary decreases, e.g., at the free space between the individual fibers. The flow of liquid into a porous medium by differential pressure DP is described by Darcy’s law1 : h ¼ 2KDP Z 1 2 t 1 2 (1) where h is the distance of liquid introduced within a period t, K the permeability of the porous body, Z the viscosity of liquid. The permeability has been related with the pore size16: K ¼ fm2 k0 (2) where f is the pore fraction, m the mean hydraulic radius (pore fraction divided by the wetted surface area), and k0 a constant. The above formulae inform that the viscosity of slurry and the pore size are important factors for infiltration. Figure 2 shows the relative density of Cfiber/SiCfiller compacts with increasing solid loading of the infiltrated slurries. When using conventional press casting, relative density of the compacts decreases from 62% to 49%. This is a consequence of the incomplete infiltration of the slurry (Fig. 3), which became more obvious with increasing the solid loading of the slurry. After drying, the compacts infiltrated with 37 vol% slurry were demolded, and were split into 12 layers. The infiltration occurred both at the center and side of the fabrics. The slurry reached to the fourth layer from the side of the stack, but could not penetrate the third layer to the middle area. Infiltration of the central area of the stacked fabrics was therefore the bottleneck during press casting (Fig. 3 (2)). At the onset of infiltration, part of the slurry migrated into the largest gap, i.e., between the stacked fabrics and the mold (Fig. 1). When the fabrics are subjected to compression during mold closing, the pores and gaps between the fibers, the tows Table I. Viscosity (Pa s) of 30 Vol% SiC Slurries (11.5 Wt% PEI) at Varying pH Values Shear rates (s1 ) 1 10 100 pH 6.5 0.155 3.4 102 1.1 102 pH 7.5 0.186 3.9 102 1.2 102 pH 8.3 0.248 5.1 102 1.5 102 pH 9.3 0.301 5.9 102 1.9 102 PEI, polyethyleneimine. Fig. 1. Schematics of molds for conventional vacuum-assisted pressure casting and a new deform casting process. (a, b) Conventional fixture of a firm mold. Woven fabrics suppress the infiltration of slurry. (c) Mold with a deformable foil during initial infiltration. The fabrics are pressed by the difference of pressure (DP) inside and outside of the mold. (d) Onset of outward deformation of the foil by the slurry. (e) Completion of the foil deformation and infiltration of the slurry. (f) Removal of excess slurry by squeezing the mold. 2658 Communications of the American Ceramic Society Vol. 90, No. 8
August 2007 Communications of the American Ceramic Society 2659 the 43 vol% slurry Slurry with a solid loading of 45 vol% could (b) not homogeneously infiltrate the stack filtration through the gap between the stacked woven fab- rics and the mold is the bottleneck in the case of deform casting Once the slurry reaches the bottom of the mold and induces 8 outward deformation of the foil, the pressure that was applied to he stacked fabrics is released(Fig. 1(d)). Because the free space in the mold increases, together with the release of pressure 0≥的 pringback of the compressed stack occurs and the gap between e fabrics and the size of the macropores near the fiber bundles increase. As a result, infiltration of the slurry into the stacked promoted Because the size of the that causes the bottleneck of deform casting(gap betw stack and the mold) is la the fiber bund the stack can be infiltrated with more viscous slurry by deform Solid loading of Sic slurry (Vol%) After the infiltration, external pressure is applied to the mold to squeeze excess slurry (Fig. I (d). Because part of the excess Fig. 2. Relative density of CfberSiCiller compacts after infiltration of slurry remains after the squeezing step, the distance between the Sic slurries with increasing solid loading into 12 layers of carbon fiber fabrics increases but with the advantage that the micro-inter- fabrics. (a) press casting and(b)deform casting yarn porosity is mostly filled and the filler particles are more densely packed due to the application of slurries with increased solid loading. The samples obtained using deform casting were ind the fabrics are reduced. During press casting, the size of thus ca. 20% thicker than those fabricated by press casting pores and gaps was not strongly affected by the infiltration be cause the fabrics were stacked tightly for the high volume frac (3) FRC tion. Consequently, the infiltration was impeded when applying lurries with a high solid loading due to the increase of viscosity Figure 4 shows the results of sEM investigations performed on On the other hand, with deform casting, the density increases the FRC after 10 impregnation/pyrolysis cycles. A uniform mi- ven with increased solid loading(Fig. 2), and concentrated crostructure with a dense matrix in between the woven fiber lurries with solid loading of up to 43 vol% could fabrics can be clearly observed. In contrast to ceramic matrix homogeneously into the fabrics(Fig. 3(c)).A home composites made by the conventional PlP technique, which gen- distribution of the filler was observed throughout the sheets, and erally contains macro-inter-yarn pores even after several im- pregnation/pyrolysis cycles, such large cavities were nearly a maximum relative density of 72% was obtained when using completely filled in the samples obtained using the deform cast ing and PIP approach. A modified technique for the homogeneous infiltration of con centrated slurries into 2D-woven fiber fabrics was developed. Compared with the conventional pressure casting, the infiltra- tion behavior of viscous slurries was improved by the applic tion of a fiexible mold. The relative density of the Ciber/Sicfiller impacts fabricated by the modified technique reached up to 72%. The macro-inter-yarn pores were successfully filled by the Sic-reinforced precursor-derived Si-C-N ceramic matrix (a) Fig 3. Caber SiCiller compacts after infiltration of Sic slurries with different solid loading(a)30 vol% SiC, (b)33 vol% SiC using conven- tional press casting and after infiltration by deform casting, and(c)usin a 43 vol% SiC slurry. The images exhibit the bottom of injection was performed from the reverse side. Penetration of the slurry press casting occurred sufficiently only with low viscous 30 vo iC slurry. In contrast, homogeneous impregnation could be achieved Fig 4. Microstructure of the fiber-reinforced nc matrix compos- tn6ig the deform casting method even if 43 vol%slurry was used only to a minor extent
and the fabrics are reduced.17 During press casting, the size of pores and gaps was not strongly affected by the infiltration because the fabrics were stacked tightly for the high volume fraction. Consequently, the infiltration was impeded when applying slurries with a high solid loading due to the increase of viscosity. On the other hand, with deform casting, the density increases even with increased solid loading (Fig. 2), and concentrated slurries with solid loading of up to 43 vol% could be injected homogeneously into the fabrics (Fig. 3 (c)). A homogeneous distribution of the filler was observed throughout the sheets, and a maximum relative density of 72% was obtained when using the 43 vol% slurry. Slurry with a solid loading of 45 vol% could not homogeneously infiltrate the stack. Infiltration through the gap between the stacked woven fabrics and the mold is the bottleneck in the case of deform casting. Once the slurry reaches the bottom of the mold and induces outward deformation of the foil, the pressure that was applied to the stacked fabrics is released (Fig. 1 (d)). Because the free space in the mold increases, together with the release of pressure, springback of the compressed stack occurs and the gap between the fabrics and the size of the macropores near the fiber bundles increase.18 As a result, infiltration of the slurry into the stacked fabrics is promoted. Because the size of the capillary that causes the bottleneck of deform casting (gap between the stack and the mold) is larger than that of press casting (pores near the woven fiber bundles), the stack can be infiltrated with more viscous slurry by deform casting. After the infiltration, external pressure is applied to the mold to squeeze excess slurry (Fig. 1 (d)). Because part of the excess slurry remains after the squeezing step, the distance between the fabrics increases but with the advantage that the micro-interyarn porosity is mostly filled and the filler particles are more densely packed due to the application of slurries with increased solid loading. The samples obtained using deform casting were thus ca. 20% thicker than those fabricated by press casting. (3) FRC Figure 4 shows the results of SEM investigations performed on the FRC after 10 impregnation/pyrolysis cycles. A uniform microstructure with a dense matrix in between the woven fiber fabrics can be clearly observed. In contrast to ceramic matrix composites made by the conventional PIP technique, which generally contains macro-inter-yarn pores even after several impregnation/pyrolysis cycles,19 such large cavities were nearly completely filled in the samples obtained using the deform casting and PIP approach. IV. Conclusions A modified technique for the homogeneous infiltration of concentrated slurries into 2D-woven fiber fabrics was developed. Compared with the conventional pressure casting, the infiltration behavior of viscous slurries was improved by the application of a flexible mold. The relative density of the Cfiber/SiCfiller compacts fabricated by the modified technique reached up to B72%. The macro-inter-yarn pores were successfully filled by the SiC-reinforced precursor-derived Si–C–N ceramic matrix Fig. 2. Relative density of Cfiber/SiCfiller compacts after infiltration of SiC slurries with increasing solid loading into 12 layers of carbon fiber fabrics. (a) press casting and (b) deform casting. Fig. 3. Cfiber/SiCfiller compacts after infiltration of SiC slurries with different solid loading (a) 30 vol% SiC, (b) 33 vol% SiC using conventional press casting and after infiltration by deform casting, and (c) using a 43 vol% SiC slurry. The images exhibit the bottom of the specimen: injection was performed from the reverse side. Penetration of the slurry using press casting occurred sufficiently only with low viscous 30 vol% SiC slurry. In contrast, homogeneous impregnation could be achieved using the deform casting method even if 43 vol% slurry was used ( ) : infiltrated area). Fig. 4. Microstructure of the fiber-reinforced ceramic matrix composites after 10 impregnation/pyrolysis cycles. The space between fibers is filled homogeneously. Flaws ( ) ) were detected only to a minor extent. August 2007 Communications of the American Ceramic Society 2659
2660 Commmunications of the American Ceramic Society Vol. 90. No. 8 because of the homogeneous infiltration of the slurry into the tacked woven fabrics loS. H. Lee, M. Weinmann, and F Aldinger, "Particulate-Reinforced Precursor- tion of Pyrolysis Atmosphere and Sched- S. H. Lee, ""Processing of Carbon Fiber Reinforced Composites With Partic References ulate-Filled Precursor-Derived Si-C-N Matrix Phases", Ph D. Thesis, University compsites bey ing Precursor infiltration T. Kennedy, M. Poorteman, F Cambier, and S Hampshire, "Silicon Nitride- Silicon Carbide Nanocomposites Prepared by Water Processing of Commercially and Pyrolysis Method. Mater. Sci. Eng. A Struct, 195[1-2] 145-50 17[21917 TechnicalbuLletinfromtheProducerhttp://www.kioncorp.com/bulletins/ R.N. Singh and A R. Gaddipati ""Fiber-Containing Composite: U. SPatent Baklouti Ix. and J. F. Baumard. ""Processing 3A. Donato. C. A. Nannetti. A. Alberto. E. Borsella, S. Botti. S. Casadio ous -Al O3, -SiOz and a-SiC Suspensions With Polyelectrolytes, G. D'Alessandro. A. A. Licciulli S. Mattelli, and A. Masci, ""Process for Produc- C.,17[121387- ng Ceramic Matrix Composites by liquid Infiltration of Ceramic Polymeric Pre- IX. Zhu. F. Tang. T.S. Suzuki and Y. Sakka. "Role of the Initial Degree of cursors: U.S. Patent No. 5.853.653, 1997. mine in the Dispersion of Silicon Carbide Nanoparti- ng the Creep Behavior eram. Soc., 86[1] 18 of a 2.5D CrSiC Composite-l. Morphology and Microstructure of the As-Re- 6J. S. Reed, "Liquid Permeability of Packed Particles: Why Perpetuate the Miyashita, K. Kanda, S. Zhu, M. Mizuno, and A J. McEvily "M. Grujic, K. M. Chitajallu, and s. Walsh, - Lattice boltzma ann Method C/iC Composites at and Elevated ures, Int J. Fatigue, 24[2-4 241-8(2002 Performs, J. Mater. Sci. 41[23]7989-8000(200 eW. Krenkel and P. Schanz. "Fiber Ceramic Structures Based on Liquid Im- V Rohatgi and L.J. Lee. ""Moldability of Tactified Fiber Performs in Liquid J Compos Mater. 31 [7]720-44(1997) emperature-Induced Direct Casting of SiC: pp. 15-40. Ph. D. Thesis Takagi, M. Hatori S Aoki, and H. Matsubara. "Synthesis and Evaluation of Stuttgart. 20 of Three-Dimensional Fiber Reinforced Ceramics" pp 33546 in Ceramic Trans- alReferencefromtheProducerhttp://www.torayca.com/techreff ction, Vol 99, Edited by N. Takeda, L M. Sheppard, and J. Kon. The American index. html Ceramic Society. Westerville. OH, 1998
because of the homogeneous infiltration of the slurry into the stacked woven fabrics. References 1 F. F. Lange, W. C. Tu, and A. G. Evans, ‘‘Processing of Damage-Tolerant, Oxidation-Resistant Ceramic–Matrix Composites by a Precursor Infiltration and Pyrolysis Method,’’ Mater. Sci. Eng. A Struct., 195 [1–2] 145–50 (1995). 2 R. N. Singh and A. R. Gaddipati, ‘‘Fiber-Containing Composite’’; U.S. Patent, No. 5,407,734, 1988. 3 A. Donato, C. A. Nannetti, A. Alberto, E. Borsella, S. Botti, S. Casadio, G. D’Alessandro, A. A. Licciulli, S. Mattelli, and A. Masci, ‘‘Process for Producing Ceramic Matrix Composites by Liquid Infiltration of Ceramic Polymeric Precursors’’; U.S. Patent No. 5,853,653, 1997. 4 G. Boitier, J. Vicens, and J. L. Chermant, ‘‘Understanding the Creep Behavior of a 2.5D Cf–SiC Composite-1. Morphology and Microstructure of the As-Received Material,’’ Mater. Sci. Eng. A., 279 [1–2] 73–80 (2000). 5 Y. Miyashita, K. Kanda, S. Zhu, Y. Mutoh, M. Mizuno, and A. J. McEvily, ‘‘Observation of Fatigue Damage Process in SiC/SiC Composites at Room and Elevated Temperatures,’’ Int. J. Fatigue, 24 [2–4] 241–8 (2002). 6 W. Krenkel and P. Schanz, ‘‘Fiber Ceramic Structures Based on Liquid Impregnation Technique,’’ Acta Astronautica, 28, 159–69 (1992). 7 R. Li, ‘‘Temperature-Induced Direct Casting of SiC’’; pp. 15–40, Ph.D. Thesis, University of Stuttgart, 2001. 8 Technical Reference from the Producer, http://www.torayca.com/techref/ index.html 9 http://en.wikipedia.org/wiki/Silicon_carbide 10S. H. Lee, M. Weinmann, and F. Aldinger, ‘‘Particulate-Reinforced PrecursorDerived Si–C–N Ceramics: Optimization of Pyrolysis Atmosphere and Schedules,’’ J. Am. Ceram. Soc., 88 [11] 3024–31 (2005). 11S. H. Lee, ‘‘Processing of Carbon Fiber Reinforced Composites With Particulate-Filled Precursor-Derived Si–C–N Matrix Phases’’; Ph.D. Thesis, University of Stuttgart, 2004, pp. 24–61. 12T. Kennedy, M. Poorteman, F. Cambier, and S. Hampshire, ‘‘Silicon Nitride– Silicon Carbide Nanocomposites Prepared by Water Processing of Commercially Available Powders,’’ J. Eur. Ceram. Soc., 17 [12] 1917–23 (1997). 13Technical Bulletin from the Producer, http://www.kioncorp.com/bulletins/ heatcurable.html 14S. Baklouti, C. Pagnoux, T. Chartier, and J. F. Baumard, ‘‘Processing of Aqueous a-Al2O3, a-SiO2 and a-SiC Suspensions With Polyelectrolytes,’’ J. Eur. Ceram. Soc., 17 [12] 1387–92 (1997). 15X. Zhu, F. Tang, T. S. Suzuki, and Y. Sakka, ‘‘Role of the Initial Degree of Ionization of Polyethylenimine in the Dispersion of Silicon Carbide Nanoparticles,’’ J. Am. Ceram. Soc., 86 [1] 189–91 (2003). 16J. S. Reed, ‘‘Liquid Permeability of Packed Particles: Why Perpetuate the Carmen–Kozeny Model,’’ J. Am. Ceram. Soc., 76 [2] 547–8 (1993). 17M. Grujicic, K. M. Chittajallu, and S. Walsh, ‘‘Lattice Boltzmann Method Based Computation of the Permeability of the Orthogonal Plane-Weave Fabric Performs,’’ J. Mater. Sci., 41 [23] 7989–8000 (2006). 18V. Rohatgi and L. J. Lee, ‘‘Moldability of Tactified Fiber Performs in Liquid Composite Molding,’’ J. Compos. Mater., 31 [7] 720–44 (1997). 19T. Takagi, M. Hatori, S. Aoki, and H. Matsubara, ‘‘Synthesis and Evaluation of Three-Dimensional Fiber Reinforced Ceramics’’; pp. 335–46 in Ceramic Transaction, Vol. 99, Edited by N. Takeda, L. M. Sheppard, and J. Kon. The American Ceramic Society, Westerville, OH, 1998. & 2660 Communications of the American Ceramic Society Vol. 90, No. 8
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