| This paper is focused on space light reflecting mirror. Developed the study on preparation technology of short SiC fiber reinforced Silicon Carbide Ceramic Matrix Composite (SiCf/SiC). Weaved the short SiC fiber to needle punching felt. SiC coating on the surface of SiC fiber was prepared through Chemical Vapor Deposition (CVD) process. SiCf/C composite were fabricated through Precursor Infiltration Pyrolysis (PIP) process. In the end used GSI process obtain compact SiCf/SiC composite. Discussed the performance of SiCf/C composite which fabricated through different PIP process cycles, the relationship between the content of pyrolysis C and the constituent of the SiCf/SiC composite after ihrigizing reactive sintering was studied, along with the thermotics, mechanical and the microstructure. Analyzed the change of pyrolysis C and porous ratio of the SiCf/C composite which dealed with high temperature, discussed the change of capability of this time's SiCf/SiC composite.(1) The content of pyrolysis C in the SiCf/C composite was mathematically analysis. Theoretical model was builded based on the porous ratio of the SiC fiber felt, and then work out the best theory content of pyrolysis C and porosity were 41.3% and 48.7%.(2) Discussed the performance of SiCf/C composite which fabricated through different PIP cycles. Along with the PIP cycles increase, the density increased, the porosity reduced and the rapidity of the density's increased was slower. The porosity of SiCf/C composite which fabricated through 2-cycles PIP process was 46.7%, best closed to the theory porosity.(3) The component, mechanical and thermotics performance of the SiCf/SiC composite which reactive sintering by different PIP cycles was researched. The result indicated that along with the the PIP cycles increased, the residual Si content was lower and residual C was higher. The mechanical of SiCf/SiC composite was best of all when the PIP cycles were 2 and the porosity of SiCf/C composite was 46.7%, the flexural strength were 160.45MPa and 242.62Gpa. The CTE of SiCf/SiC composite was reduced along with the increase of PIP cycles. The CTE were 4.4×10-6/K, 4.2×10-6/K, 4.1×10-6/K, 3.8×10-6/K.(4) Discussed the change of capability of the SiCf/SiC composite that obtained by SiCf/C composite which dealed with high temperature. The residual Si content was lower and SiC content was higher when the density increased. But the mechanical of the SiCf/SiC composite was reduced. The flexural strength was from 160.5MPa reduced to 116.9MPa when the porosity of SiCf/C was closed.
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