SA fibers

Excellent Heat-Resistant SiC-Based Fiber (SA Fiber). 118... 

As can be seen from this figure, the heat-resistance was remarkably improved by the drastic changes in the microstructure from amorphous to polycrystalline structure. Another type of SiC-based fiber, SA fiber (2), has a sintered SiC polycrystalline structure and includes very small amounts of aluminum. This fiber exhibits outstanding high temperature strength, coupled with much improved thermal conductivity and thermal stability compared with the Nicalon and Hi-Nicalon fibers. The fabrication cost of the SA fiber is also reduced to near half of that of the Hi-Nicalon Type S [ 17]. The SA fiber makes SiC/SiC composites even more attractive to the many applications [18]. In the next section, the production process, microstructure and physical properties of the SA fiber are explained in detail. 

Fig. 10 Structural transition from Si-Al-C-O fiber to SA fiber at high temperatures...

SA fiber showed high tensile strength and modulus of over 2.5 GPa and over 300 GPa, respectively. The initial strength was preserved after heat-treatment... 

Fig. 12A,B The relation between the aluminum content and the fracture behavior of the SA fiber...

Next, the alkali-resistance of SA fiber is described in detail compared with other type of SiC polycrystalline fiber using boron instead of aluminum as the... 

Fig. 15 The result of the creep-resistance of SA fiber in comparison with other SiC-based fibers...

Fig. 19 8HS fabric made of a very thin SA fiber (diameter 7 8 ]im)... 

Thermally Conductive, Tough Ceramic Making the Best Use of Production Process of SA Fiber... 

R. Yamada, N. Igawa, and T. Taguchi, Thermal DifFusivity/Conductivity of Tyranno SA fiber and Hi-Nicalon Type S Fiber-reinforced 3-D SiC/SiC Composites, J, Nucl. Mater., 329-333, 497-501 (2004). 

In order to investigate the effectiveness of EPD for carbon coating on the SiC fibers, carbon coating was formed on Tyranno SA fibers by dip-coating and vacuum infiltration, and the appearances of the carbon coating on SiC fibers by these processes were compared with that of carbon coating by EPD (Yoshida, Matsukawa,... 

Schematic illustrations of EPD equipment for interface coating on SiC fibers and the formation of SiC matrix within SiC fiber preform are shown in Figure 5. Polycrystalline Tyranno SA fibers were uni-directionally aligned and then fixed on a jig, and the silver paste was applied on the upside of the SiC fiber preform. Aqueous suspension of graphite particles for EPD was prepared using a commercial colloidal graphite aqueous solution, and the concentration of colloidal graphite suspension was set at 0.1, 0.2 and 0.3 wt%. A small amount of n-butylamine was added to the suspension to adjust the pH to 10. The uni-directional SiC fiber preform and graphite plates were used as the anode and the cathode, respectively. They were placed at a distance of 10 mm in the colloidal graphite aqueous suspension under an applied voltage of 3 V for 1 h.

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