Characterization and control of the fiber-matrix interface in ceramic ...

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98 Table 10.1. Property summary for Nicalon/SiC composite specimens. Theoretical Flexure Sample Density density strength No. Position (g/cm3> (8) (MPa) 170 TOP Middle Bottom 2.4333. 03 2.3533. 03 2.2833.03 171 TOP 2.41f0.04 Middle 2.34f0.04 Bottom 2.22k0.04 172 TOP Middle Bottom 2.48fO. 03 2.36k0.03 2.20f0.04 173 TOP 2.46f0.03 Middle 2.35f0.01 Bottom 2. 1133 .03 83.5k1.0 80.9fl. 0 78.4k1.2 82.8fl. 3 80.5kl. 5 76. If1 .3 85.3k0.9 81. lfl. 0 75.6fl. 3 84.6f1.0 80.820.3 72.4fl. 0 99.0k4.1 82.2215.5 82.7f3.9 424.8224.9 414.9210.5 326.758.3 109.529.7 88.3f13.3 125.2f16.7 100.3f14.2 77.8f8.9 61.827 .8 174 TOP 2.51k0.03 86.2f0.9 419.3f24.4 Middle 2.44k0.02 83.8f0.7 380.754.2 Bottom 2.31f0.04 79.2f1.4 369.2f11.6 175 TOP Middle Bottom 2.40f0.01 2.2720.06 2.09k0.05 82.5k0.5 78.0f2.0 71.9fl. 9 176 TOP 2.50f0.03 85.9f0.9 Middle 2.48k0.05 85.3f1. 7 Bottom 2.35k0.01 80.8f0.5 177 TOP Middle Bottom 178 TOP Middle Bottom 2.42f0.03 2.35f0.05 2.13f0.07 2.47f0.01 2.37f0.03 2.18k0.03 83. lfl. 6 80.921.7 73.3f2.6 84.850.3 81.5fl. 2 74.9f1.2 179 TOP 2.3920.02 82.1fO. 8 Middle 2.2420.04 77.051.5 Bottom 1.87k0.04 64.2fl.4 180 TOP Middle Bottom 180 Topa (oxidized) Middlea Bottoma asingle specimen 2.53f0.01 2 r42f0.02 2.23f0.01 2.51 2.40 2.21 87.250.1 83.3f0.4 76.8f0.4 86.4 82.6 76.0 98.0f7.2 401.224.9 286.2219.6 91.022.8 91.155.1 94.1f4.5 138.8529.5 104.0+8.2 99.0+21.0 89.1k9.5 82.0212.4 74.7k8.3 61.8f23.5 77.729 .O 32.052.2 419.2fl. 9 375.324.4 346.0+10.9 207.3 173.1 185.2
99 compared with the dimensions acquired using the ocular scale of the indentor. A summary of the calculated interfacial frictional stresses is given in Table 10.2. 10.3 Fib er Tensile Streneth The tensile strengths of the coated and heat-treated Nicalon fiber yarns are listed in Table 10.3. The listed results include data retrieved from the literature (119-123). Nicalon tows coated with either silicon from silane or silicon carbide from methylsilane could not be tested. The fibers failed during heat treatment, and therefore, the strength of these samples could not be evaluated. 10.4 Fracture Behavior and Interf acial Stresses 10.4.1 Silicon carbide coatina The sample composed of uncoated fibers and the composites prepared from preforms treated with thin coatings of SIC from methylsilane exhibited low flexure strength. The specimens displayed completely brittle failure, with no signs of fiber pull-out. Load-deflection curves and photomicrographs of the fracture surface of these composites are shown in Figure 10.3. Auger analysis of fracture surfaces of composite specimens with silicon carbide coatings, either from methylsilane or MTS, provided evidence of an oxygen-rich layer on the fiber surfaces and in the pull- out grooves (Figures 10.4 and 10.5). A silica layer forms on the surface of the fibers during heating, and this layer adheres well to the fiber and the subsequent Sic coating. SEM photographs of fracture surfaces of
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ORNL/TM-11039 Metals and Ceramics D
Page 6 and 7:
Page 9.3 Composite Fabrication . .
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LIST OF TABLES Table Page 5,l. Prop
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Figure 8.3. 9.1.. 9.2. 9.3. 9.4. 9.
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Figure 10.18. 10.19. 10.20. 10. 21.
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ACKNOWLEDGMENTS The author wishes t
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CWCTERIZATION AND CONTROL OF THE FI
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1. INTRODUCTION During the last sev
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The development of low-density, hig
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3. FABRICATION TECHNIQUES 3.1 Intro
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11 isostatic pressing (HIP), can be
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13 utilizing the comparatively low-
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16 ORN L- DWG 85- 4 i 4 18RS HEAT1
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5. COMPOSITE DESIGN 5.1 Introductio
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21 5,2 Mechanical Considerations Th
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23 GRNL-DWG 88-74 26 Figure 5.1. Th
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25 Equation (6) shows that the stre
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27 of reinforcement. There are two
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29 in strength. Conversely, the fib
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-I_- Table 5.2. Thermally induced a
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33 1.2 ID 0.8 ;.r 1 e fi v 0.6 a4 Q
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35 will affect the interface and, t
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38 fiber-matrix bonding; thus, a fu
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40 In the analysis of the mechanica
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42 1.2 I .o .6 - E f aa '3 0.6 cn 3
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44 will result in the matrix being
Page 64 and 65: I I MATRIX MATRIX Figure 7.1. Schem
Page 66 and 67: 48 F = 2a2H, where H is the hardnes
Page 68 and 69: 50 OWL-PHOTO 6866-86 i d c I 20pm F
Page 70 and 71: 52 where Af is the surface area of
Page 72 and 73: 54 Figure 7.4. Tensile and shear st
Page 74 and 75: 56 I I I / -c rc -c / . Om / / I /
Page 76 and 77: 58 ORNL-OWG 87-i 8234 F Figure 7.7.
Page 78 and 79: coating and the distribution of she
Page 80 and 81: 62 O m PHOTO 6676-87 i SIC FIBERS -
Page 83 and 84: the composite, therefore an interme
Page 85 and 86: methane as the reactant and is, thu
Page 87 and 88: 9. EXPERIMENTAL PROCEDURES 9.1 Depo
Page 89 and 90: 71 furnace. The furnace is, therefo
Page 91 and 92: 73 further protection. A 6.5-cm-dia
Page 94 and 95: 76 of the specimen slowly decreased
Page 96 and 97: 78 The programmer is also equipped
Page 98 and 99: 80 graphite holders through multipl
Page 100 and 101: 82 temperature by simply switching
Page 102 and 103: 84 ORNk DWG 87- 4494 3 METAL LOGR A
Page 104 and 105: 86 9.5 Fracture Surface Analvsis Th
Page 106 and 107: 88 treated and untreated halves wer
Page 108 and 109: 90 9.8.2 Tensile testinq In an init
Page 110 and 111: 92 ORNL-DUG 85-11767R.2 ? ! 2 f CEN
Page 112 and 113: 94 fracture of individual Nicalon f
Page 114: 96 Figure 10.1. SiC-infiltrated Nic
Page 119 and 120: 101 Table 10.3. Strength and modulu
Page 121 and 122: 100 ORNL- DWG 87-1 6292 R CVI-I73 7
Page 123 and 124: BULK FIBER SAMPLE NO. 173: FIBER SU
Page 125 and 126: 107 similar samples show the film o
Page 127 and 128: Figure 10.7. SEM micrographs showin
Page 129 and 130: 111 Table 10.4. Thermochemical eval
Page 131 and 132: 100 ORNL-DUG 87-15969R CVI- 170 75
Page 133 and 134: 115 Analysis conversion of of the m
Page 135 and 136: 117 A 1 I S N 31 N I I'd I LN 3H 3
Page 137 and 138: 119 n 0 W n 9 v P n w- n v
Page 139 and 140: 121 s m f c I m z - Ir 2 a 0 9 In u
Page 141 and 142: Figure 10.14. SEM micrographs of in
Page 143 and 144: J ORNL-DWC 88-6289 z cF u) w I- z O
Page 145 and 146: 127 300 I CVI-480 I I 1 0 R N L-DWG
Page 147 and 148: io0 I I I I CVI- 172 75 - - 0 z v -
Page 149 and 150: 131 RAL 033021 RAL 033023 Figure 10
Page 151: 133 include: the reaction of boron
Page 154 and 155: 136 that BN coatings react with the
Page 156 and 157: 75 7 ORNL-DWG 87-48234 50 - - c5 z
Page 158 and 159: 140 Table 10.9. Thermochemical eval
Page 160 and 161: OANL-bwo 88-9025 ORNL-DWG 66-9027 I
Page 162 and 163: 144 uncoated tows were 14 k 2 pm; t
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11. DISCUSSION 11.1 Constituent Pro
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149 The properties of CVD Sic have
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151 11.2.1 Matrix cracking In the N
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153 OWL-DWG 88-10677 CVI- (78 22 I
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155 Table 11.3. Property comparison
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157 a f ““f f- L c I Figure 11.
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159
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161 The equations demonstrate that
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163 calculations of the matrix depo
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165 In four of the samples, the fib
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167 Table 11.4. Properties of glass
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169 rare-earth magnets and coils to
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171 stress fields along the fiber i
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173 11.3.2 Tensile testinp, The use
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17 5 contraction have been ignored,
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177 the system, and when the result
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180 reduces fiber strength. The str
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182 15. R. A. J. Sambell, D. H. Bow
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184 41. A. J. Caputo et al., "Fiber
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186 71, N. F. DOW, Study of Stresse
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188 98. M. H. Rawlins et al., "Inte
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190 125. R. Warren and C-H. Anderss
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192 155. M. F. Doerner and W, D. Ni
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APPENDIX A. AUGER ELECTRON SPECTROS
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APPENDIX B DETAILS OF THE FIBER-SHE
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200 Those for the fiber (primed) ar
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202 89-92. 93. 94. 95" 96. 97. 98-9
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204 130-133. E. I. DUPONT DE NEMOUR
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206 173. NATIONAL ACADEMY OF SCIENC
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208 203 - 204. 20s. 206 - 207. 208.
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Characterization and control of the fiber-matrix interface in ceramic ...

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