A high relative desity C/ C-SiC composites were prepared by pressureless reactive infiltration of mol鄄
ten Si or Si0. 9Zr0. 1 alloy into the porous C/ C preform at 1 550益. Effects of different carbon matrixes of porous C/ C
preform including pyrolytic carbon and chemical vapor deposited carbon on the behaviors of melt Si or Si0. 9Zr0. 1 alloy
infiltration into the porous perform, the degree of reaction, the reaction phases contents and microstructures were in鄄
vestigated. The results showed that the molten Si or Si0. 9Zr0. 1 alloy was infiltrated into the large pores among adjacent
carbon fiber bundles and some small pores among carbon fibers. The melts were infiltrated more easily into the porous
C/ C preform with pyrolytic carbon and reacted completely between pyrolytic carbon and melts. The composite was
composed of SiC, ZrC, ZrSi2 phases and without free Si. Some carbon fibers reacted partially with melt in the porous
C/ C preform with pyrolytic carbon, which leaded to potential damage of the carbon fibers. However, the chemical va鄄
por deposited carbon of outer surface of the carbon fiber only reacts with infiltrating melts to form a thin SiC layer,
which protected carbon fibers and maintained the improved performances. The microstructural formation mechanism of
the C/ C-SiC composites prepared by reactive melt infiltration was proposed:the formation of the early stage was con鄄
trolled by solution鄄precipitation,and the subsequent growth was controlled by diffusion of C through the SiC layer.