Microstructures and mechanical behaviors of CVI-based C/C composites containing h-BN powdered additives

• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2019,（12）
• 页码范围: 2824-2831
• 页数: 8页
• 语种: 英文

摘要

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 PyC 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 PyC 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 ofh-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.