N.P. Bansal, J.A. Setlock/Composites: Part A 32(2001)1021-1029 1029 observed indicating toughening behavior. An sem micro- References graph of the polished cross-section of a Hi-Nicalon/BN/ BSAS composite, formed under more aggressive processing [1] Talmy IG. Haught DA. Ceramics in the system BaO-AlO3'2SiO2- conditions and flexure tested at room temperature under SrOAlOr 2SiO2 for advanced radome application. Naval Surface ambient conditions, is presented in Fig. 12. Debonding at the Warfare Center Technical Report. NSWC TR 89-162, September, fiber-matrix interface and crack deflection around the rein- [2] Lee KN. Current status of environmental barrier coatings for Si-based forcing fibers is observed, indicating a tough composite. The ceramics. Presented at The Intemational Conference on Metallic results of this study clearly indicate that reinforcement of Coatings and Thin Films(ICMCTF), San Diego, CA, April 10-14, BSAS matrix with Hi-Nicalon fibers having a duplex BN/ SiC coating results in a strong and tough composite at room [3] Bansal NP. Ceramic fiber reinforced glass-ceramic matrix compo- temperature. site. US Patent 5, 214, 004, May 25, 1993. [4] Bansal NP. Method of producing a silicon carbide fiber reinforced strontium aluminosilicate glass-ceramic matrix composite. US Patent 4. Summary 5,389,321, February14.1995 [5 Bansal NP. CVD SiC fiber-reinforced barium aluminosilicate ass-ceramic matrix composites. Mater Sci Engng. A Hot pressing of a mixed powder of BSAs composition 1996:220(1-2):129-39 obtained from calcination of metal carbonates and oxides 6 Bansal NP. Formation of monoclinic celsian in silicon results in monoclinic celsian with complete absence of the fiber-reinforced barium aluminosilicate undesirable hexacelsian phase. A method has been developed composites. NASA Technical Memorandum 10699 for the fabrication of small diameter multifilament tow fiber- reinforced ceramic matrix composites. BN/SiC-coated Hi- [7] Takeuchi Y. A detailed investigation of the structure of hexagonal BaAl2Si2Os with reference to its a-B inversion. Miner J Jp Nicalon fiber-reinforced monoclinic celsian composites have been produced by impregnation of the matrix slurry into the [8] Bahat D. Kinetic study on the hexacelsian-celsian phase transforma- ber tows, winding the tows on a drum cutting and stacking of tion. J Mater Sci 1970: 5: 805-10 the prepreg tapes, and hot pressing. Strong, tough, and almost transformation in SrAlSiyOs J Am Ceram Soc 1993: 76(5): 1321-4 fully dense unidirectional composites having -42 vol of [10] Bansal NP, Hyatt MJ, Drummond CH Crystallization and properties fibers were obtained. These composites exhibited graceful of Sr-Ba aluminosilicate glass-ceramic matrices. Ceram Engng sci failure with extensive fiber pull out in a three-point flexure Proc1991;12(7-8):122-34 test. The yield stress of -400-470 MPa and ultimate strength [11] Bansal NP, McCluskey P, Linsey G, Murphy D, Levan G Nicalon high as 960 MPa have been observed. The yield strain was fiber-reinforced celsian glass-ceramic matrix composites. Proceed- -0. 26-0.28%. The Youngs modulus of the composite was ings of Annual HITEMP Review, Cleveland, OH. October 23-25 measured to be -165 GPa 1995. NASA Conference Proceedings 10178, vol 3, 1995.p41-1- 41-14 [12] Bansal NP Processing and properties of HPz fiber-reinforced celsian 5 Conclusions c matrix composites, In preparation. [13] Bansal NP. Solid state synthesis and properties of monoclinic celsian. J Mater Sci1998:33(19):4711-5 It may be concluded that reinforcement of the monoclinic [14] Takeda M, Sakamoto J, Imai Y, Ichikawa H, Ishikawa T Properties of celsian with BN/SiC-coated Hi-Nicalon fiber results in stoichiometric silicon carbide fiber derived from polycarbosilane almost fully dense composites which are strong and tough Ceram Engng Sci Proc 1994: 15(4): 133-41 at room temperature [15] Takeda M, Sakamoto J, Saeki S, Imai Y, Ichikawa H. High silicon carbide fiber Hi-Nicalon for ceramic matrix sites. Ceram Engng Sci Proc 1995: 16(4): 37-44. Acknowledgements [16] Prewo KM. Fiber-reinforced glasses and glass-ceramics. In: Lewis MH, editor. Glasses and Glass-Ceramics. New York: Chapman Thanks are due to Rob Dickerson, Terry Kacik, Ron Hall1989.p.336-68. [17] Gouadec G, Colomban P, Bansal NP. Raman study of Hi-Nicalon Phillips and Ralph Garlick for technical assistance during fiber reinforced celsian matrix composites. Part 1: distribution and this research nanostructure of different phases. J Am Ceram Soc, in press   &  &  &   ;4  &       $  %%'%      &&  &     L                
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