Fabrication Of Carbon Fiber Reinforced SiC And Si₃N₄ Composites Via Polymer Pyrolysis Assisted By Hot-Pressing

In this paper, three-dimensional braided carbon fiber(3D-B Cf) reinforced Cf/SiC and Cf/Si3N4 composites were fabricated via precursor infiltration and pyrolysis.The influence of different hot-press temperature on the densities and the properties of Cf/SiC via pyrolysis of polycarbosilane (PCS) was studied.The pivotal factor on precursor infiltration and pyrolysis (PIP) was researched via pyrolysis of polysilazane (PSZ) by different heating rates.The influence of different surface of carbon fibers on the properties of compoites was discussed.The results showed that the properties of the composites were improved greatly by using hot -pressing after first dipping during the processing of PIP. 1600℃ was the most suitable hot-press temperature on the processing of fabricating Cf/SiC via pyrolysis of PCS.At this temperature,the average flexural strength preponderated over 500MPa, the most excellent composite could reach 672MPa and the fracture toughness was 18.9 MPa · m1/2.By the research,we found that the heating rate was the pivotal factor on PIP,also it was the major reason of good properties of composites fabricated by PIP assisted by hot-pressing.The average flexural strength of the Cf/Si3N4 composites amounted to 604MPa.The results also showed that different surface of carbon fibers should influence the properties of the composites greatly.The Jilin-carbon fibers of 2# pastern fit to fabricating Cf/SiC ceramic matrix composites by using PIP processing.