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

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180 reduces fiber strength. The strongest composites having the largest displacement to failure resulted from the thicker carbon precoats. The fibers were well protected from chemical attack, the coatings did not react chemically with the fibers, and the materials provided adequate bonding and slip, thereby preventing brittle failure. Continuing development will be aimed at observation of the smaller filaments in an SEM while applying the load. The method is versatile and rather uncomplicated; it can be applied to a large number of fiberinterlayer-matrix systems more easily than other techniques. A morecomplete analysis of the mechanics of the system is also necessary to account for factors such as Poisson's contraction and nonlinear distribution of forces along the interface. An instrumented indentation system is in the development stages. Work was initiated in collaboration with T. Coyle, D. Cranmer, and E. Fuller at the National Bureau of Standards (now National Institute of Standards and Technology), Gaithersburg, Maryland, in examining the various phenomena associated with fiber debonding and slip. In contrast to the work being completed by Marshall and Oliver (156) using the Nanoindentor to apply a load to the fibers in a composite to examine these stages of fiber displacement, a standard microhardness indentor is employed. This allows the loads to be increased to 20 N compared with the Nanoindentor's 0.12 N limit. The instrument(s) will be used to investigate the individual forces of debonding and frictional sliding. It appears that a thorough understanding of both forces is necessary to explain observed mechanical behavior in composite materials.
REFERENCES 1. A. H. Cotrell, "Strong Solids," PKOC. R. SOC. London A282, 2-9 (1963). 2. A. Kelly, "The Strengthening of Metals by Dispersed Particles," Proc, R. SOC. London A282, 63-79 (1964). 3. H. W. Rauch, W. H. Sutton, and L. R. McCreiglit, Ceram.i.c Fibers and Fibrous Composite Materials, Academic Press, New York, 1968. 4. J. D. Walton and W. J. Corbett, "Metal Fiber Reinforced Ceramics, pp. 223-38 in Fiber Composite Materials, American Society of Metals Seminar, October 1964. 5. D. C. Phillips, "Fibre Reinforced Cerami.cs9" pp. 373-428 in fiatidhook of Composites, Volrime 4 - Fabrication of Composites, edited by A. Kelly and S. T. Mileiko, Elsevier Science Publishers B. V., North- Holland, The Netherlands, 1983. 6. L. S. Millberg, ''The Search for Ductile Ceramics," J. Metals 39(11), 10-13 (1987). 7. L. Holiday, "Ceramic Systems," pp. 91-127 in Composit-e Materials, Elsevier Publishing Company, New York, 1966. 8. Y. Baskin, A. Arenberg, and J. H. Handwerk, "Thoria Reinforced by Metal Fibers," Ceram. Bull. 38, 345-48 (1959). 9. Y. Baskin, Y. Horado, and J. M. EIandwerk, "Some Physical. Properties of Thoria Reinforced by Metal Fibers," J. Am. Ceram. Soc. 43, [+98-92 (1960). 10. J. R. Tinklegaugh, "Ceramic-Metal Fibre Gonipsite Systeiiis, I' p. 579 in Strengthening Meehanisms: Metals and Ceramics, edited by J. J, Burke, N. L. Reed, and V. Weiss, 1.2th Sagamore Army Materials Research Conference, Syracuse University Press, 1965. 11. D. C. Phillips, "The Fracture Energy of Carbon-Fiber Reinforced Glass," J. Mater. Sci. 7, 1175-91 (1972). 12. a. C. Phillips, "Interfacial Bonding and the Toughness of Carbon Fibre Reinforced Glass and Glass-Ceramics, 'I J. Mater. Sc.i. 9, 1847- 54 (1974) . 13, D, C. Phillips, R. A. J. Sambell, and D. H. Bowen, "The Mechanical Properties of Carbon Fibre Reinforced Pyrex Glass," J. Mater. Sci. 7, 1454-64 (1972). 14. R. A. J. Sambell et al., "Carbon Fiber Composites with Ceramic and Glass Matrices, Part 2: Continuous Fibres," J. Mater. Sci. 7 , 676-81 (1972). 181
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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
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I I MATRIX MATRIX Figure 7.1. Schem
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48 F = 2a2H, where H is the hardnes
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50 OWL-PHOTO 6866-86 i d c I 20pm F
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52 where Af is the surface area of
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54 Figure 7.4. Tensile and shear st
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56 I I I / -c rc -c / . Om / / I /
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58 ORNL-OWG 87-i 8234 F Figure 7.7.
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coating and the distribution of she
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62 O m PHOTO 6676-87 i SIC FIBERS -
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the composite, therefore an interme
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methane as the reactant and is, thu
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9. EXPERIMENTAL PROCEDURES 9.1 Depo
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71 furnace. The furnace is, therefo
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73 further protection. A 6.5-cm-dia
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76 of the specimen slowly decreased
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78 The programmer is also equipped
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80 graphite holders through multipl
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82 temperature by simply switching
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84 ORNk DWG 87- 4494 3 METAL LOGR A
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86 9.5 Fracture Surface Analvsis Th
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88 treated and untreated halves wer
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90 9.8.2 Tensile testinq In an init
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92 ORNL-DUG 85-11767R.2 ? ! 2 f CEN
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94 fracture of individual Nicalon f
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96 Figure 10.1. SiC-infiltrated Nic
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99 compared with the dimensions acq
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101 Table 10.3. Strength and modulu
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100 ORNL- DWG 87-1 6292 R CVI-I73 7
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BULK FIBER SAMPLE NO. 173: FIBER SU
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107 similar samples show the film o
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Figure 10.7. SEM micrographs showin
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111 Table 10.4. Thermochemical eval
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100 ORNL-DUG 87-15969R CVI- 170 75
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115 Analysis conversion of of the m
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117 A 1 I S N 31 N I I'd I LN 3H 3
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119 n 0 W n 9 v P n w- n v
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121 s m f c I m z - Ir 2 a 0 9 In u
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Figure 10.14. SEM micrographs of in
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J ORNL-DWC 88-6289 z cF u) w I- z O
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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
Page 165 and 166: 11. DISCUSSION 11.1 Constituent Pro
Page 167 and 168: 149 The properties of CVD Sic have
Page 169 and 170: 151 11.2.1 Matrix cracking In the N
Page 171 and 172: 153 OWL-DWG 88-10677 CVI- (78 22 I
Page 173 and 174: 155 Table 11.3. Property comparison
Page 175 and 176: 157 a f ““f f- L c I Figure 11.
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Page 179 and 180: 161 The equations demonstrate that
Page 181 and 182: 163 calculations of the matrix depo
Page 183 and 184: 165 In four of the samples, the fib
Page 185 and 186: 167 Table 11.4. Properties of glass
Page 187 and 188: 169 rare-earth magnets and coils to
Page 189 and 190: 171 stress fields along the fiber i
Page 191 and 192: 173 11.3.2 Tensile testinp, The use
Page 193 and 194: 17 5 contraction have been ignored,
Page 195: 177 the system, and when the result
Page 200 and 201: 182 15. R. A. J. Sambell, D. H. Bow
Page 202 and 203: 184 41. A. J. Caputo et al., "Fiber
Page 204 and 205: 186 71, N. F. DOW, Study of Stresse
Page 206 and 207: 188 98. M. H. Rawlins et al., "Inte
Page 208 and 209: 190 125. R. Warren and C-H. Anderss
Page 210 and 211: 192 155. M. F. Doerner and W, D. Ni
Page 213 and 214: APPENDIX A. AUGER ELECTRON SPECTROS
Page 215: APPENDIX B DETAILS OF THE FIBER-SHE
Page 218 and 219: 200 Those for the fiber (primed) ar
Page 220 and 221: 202 89-92. 93. 94. 95" 96. 97. 98-9
Page 222 and 223: 204 130-133. E. I. DUPONT DE NEMOUR
Page 224 and 225: 206 173. NATIONAL ACADEMY OF SCIENC
Page 226 and 227: 208 203 - 204. 20s. 206 - 207. 208.
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