Abstract
The operation of the process of chemical vapor infiltration using a combination of pressure pulsing and thermal gradients is theoretically investigated in this study. Past studies had shown that pulsing of the pressure in the gas phase can lead to a dramatic reduction of the density gradients in the densifying structure, in comparison to those seen in isobaric diffusion-driven Pinfiltration, with significant gradients present only in the vicinity of the external surface of the preforms. Using a detailed model for chemical vapor infiltration under unsteady nonisothermal conditions, we show that temperature gradients, created in our study through microwave heating, can, in conjunction with pressure pulsing, eliminate the density gradients in the final product. Moreover, appropriate tuning of the operational parameters can lead to a situation where densification proceeds from the interior of the preform toward the external surface.
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References
G. Savage, Carbon-Carbon Composites (Chapman and Hall, London, 1993).
K. K. Chawla, Ceramic Matrix Composites (Chapman and Hall, London, 1993).
R. Naslain, in Ceramic Matrix Composites, edited by R. Warren (Chapman and Hall, Glasgow, 1992).
K. Sugiyama and Y. Kurisu, J. Mater. Sci. 27, 4070–4074 (1992).
S. V. Sotirchos, AIChE J. 37, 1365–1378 (1991).
S. V. Sotirchos, in High Temperature Ceramic Matrix Composites, edited by R. Naslain, J. Lamon, and D. Doumeingts (6th European Conference on Composite Composite Materials, Bordeaux, France, 1993).
W. H. Sutton, A. Ceram. Soc. Bull. 68, 376–386 (1989).
D. Gupta and J. W. Evans, J. Mater. Res. 6, 810–818 (1991).
D. Gupta and J. W. Evans, J. Am. Ceram. Soc. 76, 1924–1929 (1993).
J. I. Morell, D. J. Economou, and N. R. Amundson, J. Mater. Res. 8, 1057–1067 (1993).
D. J. Devlin, R. P. Currier, R. S. Barbero, and B. F. Espinoza, Ceram. Eng. Sci. Proc. 14 (9/10), 761–767 (1993).
M. S. Spotz, D. J. Skamser, P. S. Day, H. M. Jennings, and D. L. Johnson, Proc. 17th Annual Conference on Advanced Composites and Advanced Ceramic Materials, Cocoa Beach, FL (1993), pp. 753–760.
K. Sugiyama and Y. Ohzawa, J. Mater. Sci. 25, 4511–4517 (1990).
E. A. Mason and A. P. Malinauskas, Gas Transport in Porous Media: The Dusty-Gas Model (Elsevier, New York, 1983).
R. Jackson, Transport in Porous Catalysts (Elsevier, New York, 1977).
S. V. Sotirchos, AIChE J. 35, 1953–1961 (1989).
V. N. Burganos and S. V. Sotirchos, Chem. Eng. Sci. 44, 2451–2462 (1989).
M. M. Tomadakis and S. V. Sotirchos, J. Chem. Phys. 98, 616–626 (1993a).
S. Kirkpatrick, Rev. Mod. Phys. 45, 574 (1973).
M. M. Tomadakis and S. V. Sotirchos, AIChE J. 39, 397–412 (1993b).
R. C. Reid and T. K. Sherwood, The Properties of Gases and Liquids (McGraw-Hill, New York, 1966).
C. A. Balanis, Advanced Engineering Electromagnetics (John Wiley, New York, 1989).
K. G. Ayappa, H. T. Davis, E. A. Davis, and J. Gordon, AIChE J. 37, 313–322 (1991).
D. J. Devlin, R. P. Currier, R. S. Barbero, B. F. Espinoza, and N. Elliot, in Chemical Vapor Deposition of Refractory Metals and Ceramics II, edited by T. M. Besmann, B. M. Gallois, and J. Warren (Mater. Res. Soc. Symp. Proc. 250, Pittsburgh, PA, 1992), pp. 245–250.
M. A. Janney, H. D. Kimrey, J.O. Kiggans, in Microwave Processing of Materials III, edited by R. L. Beatty, W. H. Sutton, and M. F. Iskander (Mater. Res. Soc. Symp. Proc. 269, Pittsburgh, PA, 1992), pp. 173–185.
R. E. Treybal, Mass Transfer Operations (McGraw-Hill, Tokyo, 1981).
G. D. Papasouliotis and S. V. Sotirchos, in Gas-Phase and Surface Chemistry in Electronic Materials Processing, edited by T. J. Mountziaris, G. R. Paz-Pujatt, F. T. J. Smith, and P. R. Westmoreland (Mater. Res. Soc. Symp. Proc. 334, Pittsburgh, PA, 1994), pp. 111–116.
K. Brennfleck, E. Fitzer, G. Schoch, and M. Dietrich, in Proc. Ninth Int. Conf. on CVD, edited by M. Robinson, C. H. J. van den Brekel, G. W. Cullen, J.M. Blocher, and P. Rai-Choudhury (The Electrochem. Soc., Pennington, NJ, 1984), pp. 649–662.
C. DeBoor, A Practical Guide to Splines (Springer-Verlag, New York, 1978).
C. W. Gear, Numerical Initial Value Problems in Ordinary Differential Equations (Prentice Hall, Englewood Cliffs, NJ, 1971).
I. B. Fieldhouse, J.C. Hedge, J.I. Lang, and T. E. Waterman, Thermal Properties of High Temperature Materials, Armour Research Foundation, WADC-TR-57-487, AD-150954, Contract AF-33(616)-3701 (1958).
Refractory Ceramics for Aerospace, edited by J.R. Hague, J.F. Lynch, A. Rudnick, F. C. Holden, and W.H. Duckworth (ACS, Columbus, OH, 1960).
G. A. Slack, J. Phys. Chem. Solids 34, 321–335 (1973).
M. Tawil, L. D. Bentsen, S. Baskaran, and D. P. H. Hasselman, J. Mater. Sci. 20, 3201–3212 (1985).
R. B. Bird, W. E. Stewart, and E. N. Lightfoot, Transport Phenomena (John Wiley, New York, 1960).
C. R. Wilke, J. Chem. Phys. 18, 517–519 (1950).
R. A. Svehla, NASA Tech. Rept. R-132, Lewis Research Center, Cleveland, OH (1962).
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Ofori, J.Y., Sotirchos, S.V. Dynamic convection-driven thermal gradient chemical vapor infiltration. Journal of Materials Research 11, 2541–2555 (1996). https://doi.org/10.1557/JMR.1996.0320
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DOI: https://doi.org/10.1557/JMR.1996.0320