Paper number 378

EVALUATION OF ADVANCED SIC FIBERS FOR REINFORCEMENT OF CMC

H. Serizawa¹, C.A. Lewinsohn², G.E. Youngblood², R.H. Jones², D.E. Johnston³,

and A. Kohyama4
1Joining and Welding Research Institute, Osaka University
11-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
2Pacific Northwest National Laboratory,
MSIN:P8-15, P.O.Box 999, Richland, WA 99352, USA
3Department of Materials Science and Engineering, University of Washington
Robert Hall P.O.Box 352120, Seattle, WA 98195, USA
4Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan

Summary

As a result of R & D efforts for silicon carbide (SiC) fibers, a near-stoichiometric and highly crystalline SiC fiber (Hi-Nicalon type S) has been developed. In this research, to evaluate Hi-Nicalon type S for reinforcement of ceramic matrix composites, fiber tensile tests at high temperature, fiber oxidation tests and fiber bend stress relaxation tests were carried out. Hi-Nicalon fibers were also tested to compare with Hi-Nicalon type S. The strength-gauge length relationship of Hi-Nicalon type S was found to follow the weakest-link rule, described by a Weibull distribution. The results of tensile tests at high temperature indicated that the strength of oxidized Hi-Nicalon type S decreases at elevated temperature. From the SEM observation results of oxidized fibers, the oxidation behavior of Hi-Nicalon type S was found to fit the Deal/Grove linear-parabolic model. Finally, Hi-Nicalon type S fibers were more resistant to bend stress relaxation than Hi-Nicalon fibers.

Keywords

SiC fiber, high temperature, fiber tensile strength, oxidation, creep, ceramic matrix composites.