Hexagonal boron nitride(h-BN)powders were introduced into carbon fiber preform by powder addition and subsequent combined with chemical vapor infiltration(CVI)for densification to prepare carbon fiber reinforced/carbo...Hexagonal boron nitride(h-BN)powders were introduced into carbon fiber preform by powder addition and subsequent combined with chemical vapor infiltration(CVI)for densification to prepare carbon fiber reinforced/carbon and boron nitride dual matrix composites(C/C-BN).Microstructures and mechanical properties of C/C composites with three different volume contents of h-BN powders were investigated in comparison to pure C/C composites.Results indicated that the introduction of h-BN powders into C/C composites significantly reduced the size of Py C and the anisotropy of thermal contraction in matrix,leading to a gradual disappearance of ring defects as the h-BN content increased.In addition,an enhanced interfacial bonding between fiber and matrix obtained due to higher-textured Py C and rougher fiber surface.Thereby,the flexural strengths and modulus of as-prepared composites decreased firstly and then increased,while the impact toughness presented a decreasing tendency as the content of BN powders increased.Furthermore,with the increasing of h-BN content,anisotropies of compressive properties were weakened,and the compressive strength of C/C-BN composites were always higher than that of pure C/C composit.However,when C/C composites modified by 13.5 vol%content of h-BN,excessive loose BN aggregates appeared in C/C-BN composites,leading to a relatively slight reduction of compressive strength.展开更多
基金the financial supports from the Natural Science Foundation of Hunan Province(Grant No.2019JJ50768)National Natural Science Foundation of China(Grant No.51575536)+1 种基金the National High Technology Research and Development Program(Grant No.2015AA033503)Graduate degree thesis Innovation Foundation of Central South University(Grant No.2018ZZTS414)
文摘Hexagonal boron nitride(h-BN)powders were introduced into carbon fiber preform by powder addition and subsequent combined with chemical vapor infiltration(CVI)for densification to prepare carbon fiber reinforced/carbon and boron nitride dual matrix composites(C/C-BN).Microstructures and mechanical properties of C/C composites with three different volume contents of h-BN powders were investigated in comparison to pure C/C composites.Results indicated that the introduction of h-BN powders into C/C composites significantly reduced the size of Py C and the anisotropy of thermal contraction in matrix,leading to a gradual disappearance of ring defects as the h-BN content increased.In addition,an enhanced interfacial bonding between fiber and matrix obtained due to higher-textured Py C and rougher fiber surface.Thereby,the flexural strengths and modulus of as-prepared composites decreased firstly and then increased,while the impact toughness presented a decreasing tendency as the content of BN powders increased.Furthermore,with the increasing of h-BN content,anisotropies of compressive properties were weakened,and the compressive strength of C/C-BN composites were always higher than that of pure C/C composit.However,when C/C composites modified by 13.5 vol%content of h-BN,excessive loose BN aggregates appeared in C/C-BN composites,leading to a relatively slight reduction of compressive strength.
