Ïwµ½D¨(Y»PCfAEA~mPC_)/Cg}gbNX¡Þ¿ÌC ÷\¢yÑÍw¨«ÉyÚ·MÌe¿ (aeQñ) @ÑE½cDm åwåw@Hw¤Èim\¢ae[Þ¿HwêUC8900065 sS³ 12140 Influence of heat treatment at 10001500 C for 24 h on phases, microstructures and mechanical properties was studied for laminated SiC satin or aluminosilicate plain fabric/mullite matrix composites. Composites were produced by a polymer impregnation and pyrolysis method (PIP) using a mullite precursor. A mullite precursor solution of the mixtures of Si(OC 2 H 5 ) 4 and Al(NO 3 ) 3 was

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... regnated into the green layered fabric/mullite powder (filler) composite and was pyrolyzed at 500 C in air. This polymer impregnation and pyrolysis process was repeated 10 times. The SiC fabric (2527 vol÷)/mullite matrix composite with a relative density 7275÷ showed weight loss after heat treatment in an Ar atmosphere (oxygen partial pressure'0.75 Pa) at 1300 1500 C. This weight loss was due to the formation of volatile SiO gas resulting from the pyrolysis of mullite matrix (3Al 2 O 3 E2SiO 2 (s)¨3Al 2 O 3 (s){2SiO(g){O 2 (g)) and active oxidation of the SiC fiber (SiC(s){O 2 (g) SiO(g){CO(g)). The heattreated SiC fabric/mullite matrix composites showed an elastic deformation in the initial stage of the stressdisplacement curve, followed by pseudoductility. The strength (186 MPa) after the 1000 C heat treatment decreased to 17 MPa after the 1500 C heat treatment. The energy of fracture was 14 kJ/ m 2 in the heat treatment temperature range from 1000 to 1500 C.On the other hand, the aluminosilicate fabric (2530 vol÷)/mullite matrix composite with a relative density 7173÷ showed no weight loss after heat treat ment at 10001500 C in air. The porosity of the composite decreased with increasing heat treatment temperature because of the densification of the mullite matrix. This composite also showed pseudoductility after the heat treatment. The strength for the composite was slightly enhanced by increasing the heat treatment temperature. [