TiB2、CNT双相增韧碳化硼复合陶瓷及其性能研究

在1 500 ℃的真空条件下,通过液相渗硅法(liquid silicon infiltration, LSI)制备了碳化硼/二硼化钛-碳纳米管(B₄C-TiB₂-CNT)陶瓷复合材料,对其成分、形貌、性能和增韧机理进行了分析表征和研究。结果表明:复合材料的主要组成相为B₁₂(C, Si, B)₃、SiC和Si。二硼化钛和碳纳米管显著提高了液相渗硅烧结碳化硼陶瓷的力学性能,在TiB₂和CNT的添加量分别为10%和0.4%时,复合陶瓷的弯曲强度和断裂韧性达到了(390±18) MPa和(5.38±0.38) MPa·m^1/2,分别比B₄C陶瓷高了31%和53%。本文的研究从片状SiC颗粒和CNT的拔出、TiB₂的颗粒增韧以及裂纹的偏转等方面解释了B₄C-TiB₂-CNT复合材料的增韧机理。

Preparation and Characterization of TiB2 and CNT Dual-Phases Toughened B4C Ceramic Composites

B₄C-TiB₂-CNT ceramic composites were fabricated by the liquid silicon infiltration (LSI) sintering at 1 500 ℃ in vacuum. The compositions, morphologies, mechanical properties and toughening mechanism of the fabricated composites were investigated. The results show that the main constituent phases of the composites are B₁₂(C, Si, B)₃, SiC and Si. The additions of TiB₂ and CNT significantly improve the mechanical properties of liquid-phase silicon sintered B₄C ceramics. The flexural strength and fracture toughness of the composite ceramics reach (390±18) MPa and (5.38±0.38) MPa·m^1/2 with TiB₂ and CNT additions of 10% and 0.4% respectively, which are 31% and 53% higher than pure B₄C caremics. The toughening mechanisms of B₄C-TiB₂-CNT ceramic composites are explained by the pullout of plate-like SiC particles and CNT, the particle toughening of TiB₂ and the deflection of cracks.