Mechanical Properties Of 2D-SiC_f/SiC High-temperature Structural Absorbing Materials

The structural radar absorbing materials, with the dual functions of high mechanical properties and reducing radar cross section, were the key means of stealth technique implementation, especiallly to the battleplane and cruise missile and other armament in the sky, which part work temperature reached 700℃even above 1000℃. So the demands of high-temperature structural radar absorbing materials were very imminent .The absorbing properties of the 2D-SiC_f/SiC composites which were made by the KD-I SiC fibre were investigated; the technique was confirmed to decarbonize on the surface of SiC fibre; the damage mechanism of the 2D-SiC_f/SiC composites was discussed. The mechanical properties of the 2D-SiC_f/SiC composites, which was prepared by the air heat-treatment fibre, manufactured by PIP were investigated; the mechanical properties of the 2D-SiC_f/SiC composites and SiC fibre and carbon fibre laminated composites manufactured by PIP were investigated.Firstly, the absorbing properties of the 2D-SiC_f/SiC composites which was made by the KD-I SiC fibre were investigated, the result showed the 2D-SiC_f/SiC composites reflected radar very strongly. The electric properties of SiC fibre was varied by heat-treatment in the air, the heat-treatment condition of SiC fibre used for the 2D-SiC_f/SiC structural absorbing materials was 600℃/60min. Because of the serious physical damage to SiC fibre, caused by the matrix shrink during the PCS pyrolysis process, and the strong-bonding of the interface between fiber and martrix, the mechanical properties of the 2D-SiC_f/SiC composites which was prepared by the air heat treatment fibre decreased seriously.The mechanical properties of the 2D-SiC_f/SiC composites which was made by decarbonized SiC fibre were investigated by pretreatment technique. The interface of the fibre-martrix in the composites can be improved through the phenolic resin pyrolysis on the surface of the fibre, and the mechanical properties of the composites can be improved, when the mass point of phenolic resin was 20% in the solution, the flexural strengths of the composites can reach 81.6MPa, but the effects of this fiber treatment process were not evident. In order to improve the mechanical properties of the 2D-SiC_f/SiC composites furtherly, the CVD SiC coating technique was introduced. The effects of the thickness of SiC coating on the mechanical properties of the 2D-SiC_f/SiC composites were studied. When the thickness of SiC coating was approxiamte, the interface between the fiber and martrix in the composites can be improved effectively, so the mechanical properties of the composites can increase, when the CVD SiC deposition process was 1100℃/1hr. The flexural strength of the 2D-SiC_f/SiC composites can reach 125.9MPa.The mechanical properties of laminated composites which were made up of SiC fibre and carbon fibre were investigated from structural design in this paper. The 2D-Cf/SiC composites as reflective layer at the bottom of the structural radar absorbing materials played a key role in improving the mechanical properties of the composites. The mechanical properties of laminated composites which was made up of different layers SiC fibre and carbon fibre were investigated. The effects of different pyrolysis temperature on the properties of layers composites were investigated. When the number of C cloth from 2 layers increasing to 12 layers in the compsites, the flexural strength of laminated composites was inproved from 93.7MPa to 323.5MPa at 1000℃.