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Structure and Formation Kinetics of Mosi2 Composites Formed by Reactive Vapor Infiltration Process

Published online by Cambridge University Press:  15 February 2011

W.B. Hillig ,
R.M. Ramakrishnan ,
M. Broglio  and
N. Patibandla
W.B. Hillig
Affiliation:
Rensselaer Polytechnic Institute, Troy, NY 12180-3590
R.M. Ramakrishnan
Affiliation:
Xomox Corp., 4444 Cooper Rd., Cincinnati, OH 45242
M. Broglio
Affiliation:
Rensselaer Polytechnic Institute, Troy, NY 12180-3590
N. Patibandla
Affiliation:
New York State Energy Development Authority, Albany, NY, 12223
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Abstract

Reactive Vapor Infiltration is a convenient new process for producing high purity MoSi2 matrix composites by reacting compacted mixed Mo + MoSi2 powders ranging from 0 to 80 wt. % MoSi2 with H2 + SiCl4 vapors at temperatures from 1000 to 1400°C. Consideration must be taken of the volumetric increase that accompanies this conversion. The kinetics of the advance of the MoSi2 growth layer and the gravimetric uptake are given as a function of temperature and the composition. The parabolic growth rate constant was independent of composition at least up to 30% MoSi2 composition, but then showed a strong, linear increase with increasing MoSi2 content. There appeared to be a levelling off of rate above 70% MoSi2. The corresponding gravimetric rate constant was relatively insensitive to the starting MoSi2 content. This behavior is at variance with a simple one-dimensional diffusive growth model. Possible reasons for this variance are offered.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 365: Symposium M – Ceramic Matrix Composites–Advanced High-Temperature Structural Materials , 1994 , 153
Copyright
Copyright © Materials Research Society 1995

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References

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