| In this paper,the series of continuous SiC_f/SiC-CMCs were prepared by PIP process with continous SiC fibers and polycarbosilane(PCS) produced by ourselves. The manufacturing process was optimized. The effects of the types and arrangement of the SiC fibers on the structure and properties of the SiC_f/SiC-CMCs were systematically studied. Carbon coating was treated on the continuous SiC fibers in order to improve the fracture toughness of the SiC_f/SiC-CMCs. The manufacturing process of the carbon coating was researched and the structure and properties of the composites were characterized. The effects of the carbon coating on the properties, especially the fracture toughness of the SiC_f/SiC-CMCs were studied. The thermal conductivity properties of the SiC_f/SiC-CMCs were systematically researched by laser flash method, SEM, and energy spectrum analysis.The SiC_f/SiC-CMCs were prepared by PIP process with different types (common and containing aluminum) and arrangement(short-fibers,uni-direction,orthogonal laying) of SiC fibers. The results showed that the optimum manufacturing process were:the proportion of the slurry(weight) was that SiC micro-powder: PCS:Xylene=1:1:1; the rolling velocity of fibers was 5-10m/min. The pressure was 8-12MPa and the temperature was about 205℃.At room temperature, the flexural strengths of the uni-direction common SiC_f/SiC-CMCs and SiC_f/SiC-CMCs containing aluminum were 307MPa and 268.7MPa. The fracture toughness of them were 8.24MPa?m1/2 and 6.68MPa?m1/2. The common SiC fibers exhibited better reinforcement than the SiC fiber containing aluminum. The flexural strengths of the uni-direction common SiC_f/SiC-CMCs could satisfy the application requirement,but their fracture toughness is too low. The flexural strengths and fracture toughness of the orthogonal laying common SiC_f/SiC-CMCs are 170.7MPa and 9.62 MPa?m1/2. Their fracture toughness are better than uni-direction SiC_f/SiC-CMC, but the flexural strengths are too low. The results of the high- temperature strengths of the uni-direction common SiC_f/SiC-CMCs showed that their flexural strengths are 368MPa at 1000℃in vacuum environment, the retention rate was about 120%. The SiC_f/SiC-CMCs offer good high-temperature properties.Due to the low fracture toughness of the SiC_f/SiC-CMCs, carbon coating was treated on the continuous SiC fibers with batelite and pitch and the SiC_f/SiC-CMCs with the carbon coating were prepared. The results showed that the optimum manufacturing process of the carbon coating derived from batelite and pitch were that:the concentration of batelite/alcohol was 20g/L, the pyrolysis temperature was 800℃and the concentration of pitch/xylene was 4g/L, the pyrolysis temperature was 800℃.Study on the properties of the SiC_f/SiC-CMCs with carbon coating showd that the flexural strengths and fracture toughness of the common SiC_f/SiC-CMCs with carbon coating derived from batelite were 229.8MPa and 6.40 MPa?m1/2 and those of the common SiC_f/SiC-CMCs with carbon coating derived from pitch were 293.5MPa and 10.71 MPa?m1/2; as the same, those of the SiC_f/SiC-CMCs containing aluminum with carbon coating derived from pitch were 277.9MPa and 10.73 MPa?m1/2. The fracture toughness of the SiC_f/SiC-CMCs with carbon coating derived from pitch increased obviously and the flexural strength had no remarkable decrease. The purpose of improving the fracture toughness was accomplished.The effects on the thermal conductivity properties of the SiC_f/SiC-CMCs were researched, containing the types of SiC fibers,the heat treatment temperature, the arrangement of fibers,carbon coating, fibers volume fraction,porosity,and so on. The results showed that the thermal conductivity properties of the common SiC_f/SiC-CMCs (3.10W/mK)were better than the SiC_f/SiC-CMCs containing aluminum (1.51W/mK), but lower than the common short-cutted SiC_f/SiC-CMCs (4.71W/mK). Directions parallel and vertical to the fibers of the uni-direction common SiC_f/SiC-CMCs were 4.10W/mK and 3.10W/mK, the direction parallel to SiC fibers was better than the other direction. The thermal conductivity properties of the orthogonal laying common SiC_f/SiC-CMCs(2.9W/mK) was similar with the uni-direction common SiC_f/SiC-CMCs. The thermal conductivity of SiC_f/SiC-CMCs was improved by raising fiber volume fraction and heat treatment temperature, but decreased by treated with carbon coating. The thermal conductivity of the SiC_f/SiC-CMCs increased with their porosity decreased. The densification of the SiC_f/SiC-CMCs shoud be enhanced in order to improving the thermal conductivity.
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