热压辅助先驱体裂解制备的三维C_f/Si—O—C复合材料的微观结构与力学性能

Microstructures and mechanical properties of carbon fiber reinforced silicon oxycarbide composites fabricated via hot-pressing assisted pyrolysis of polysiloxane

采用聚硅氧烷(PSO)先驱体浸渍裂解工艺制备出碳纤维三维编织物增强Si—O—C复合材料(3D-B C_(?)/Si—O—C)。研究发现,第一周期采用热压辅助裂解可以显著提高材料的力学性能与致密度。第一周期经1600℃、10MPa的条件热压裂解处理5min后,材料的弯曲强度和断裂韧性从未处理前的246.2MPa和9.4MPa·m^(1/2)提高到502MPa和23.7MPa·m^(1/2)。该材料的弯曲强度在真空中可以保持到1400℃。探讨了工艺参数对材料结构与力学性能的影响。高温裂解弱化界面结合同时提高纤维就位强度以及加压提高材料致密度是热压辅助裂解能提高材料力学性能的主要原因。

Three-dimensional braided carbon fiber reinforced silicon oxycarbide composites(3DB C_f/Si—O—C) were fabricated via polysiloxane infiltration and pyrolysis. It was found that the density and mechanical properties of 3D-B C_f/ Si—O—C could be increased remarkably if the first pyrolysis was assisted by hot-pressing. When the first pyrolysis was carried out at 1600℃ for 5min with a pressure of 10MPa, the flexural strength and fracture toughness of the resultant 3D-B C_f/ Si—O—C were increased from 246.2MPa and 9.4MPa·m^(1/2) to 502MPa and 23.7MPa·m^(1/2), which was attributed to the desirable interracial bonding, increased in-situ strength and density as the results of high temperature and pressure. In high temperature flexural tests, the strength of the composite at room temperature was maintained to 1400℃ under vacuum.