激光增材/渗硅复合成形Csf/SiC复合材料的界面性能研究OA

Aiming at the problem that the internal short carbon fiber(Csf)of carbon fiber reinforced silicon carbide(Csf/SiC)composites prepared by laser powder bed molten/liquid silicon permeation(LPBF/LSI)is prone to be eroded by molten Si,which limits the strengthening and toughening effect of fibers on the matrix and restricts the performance improvement of Csf/SiC composites formed by LPBF/LSI.This study propose to coat pyrolytic carbon(PyC)and silicon carbide(SiC)coatings respectively on the surface of Csf by hydrothermal carbonization and dip coating-pyrolysis processes,and Csf/SiC composites are prepared through LPBF/LSI.The influence of the fiber surface coating on the microstructure and mechanical properties of Csf/SiC composites is studied.The results show that the SiC coating can prevent the direct contact between Csf and molten Si,avoid the dissolution-precipitation reaction at the interface between the two,and thereby protect Csf.Compared with the Csf/SiC composites with Csf and Csf@PyC,the internal fibers of the Csf/SiC composites with Csf@SiC still retained better original structure,while the Csf inside the former two showed reactive erosion.The fibers retained due to SiC coating protection improved the flexural strength and fracture toughness of Csf/SiC composites to a certain extent through crack deflection,coating de-bonding and fiber pulling mechanisms,which are 7.1％and 8.3％higher than those of Csf/SiC composites with Csf and Csf@PyC,respectively.The maximum reaches 246.09 MPa and 3.28 MPa·m1/2.In this study,the synergistic improvement of the strength and toughness of Csf/SiC composites is achieved through the optimization of fiber surface coatings,providing a certain theoretical basis for the preparation of high-performance Csf/SiC composites by LPBF/LSI.