Room and high temperature flexural failure of spark plasma sintered boron carbide
Room and high temperature flexural failure of spark plasma sintered boron carbide
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DOI：
10.1016/j.ceramint.2016.01.088
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发表时间：
2016-05
影响因子：
5.2
通讯作者：
O. Vasylkiv;D. Demirskyi;P. Badica;T. Nishimura;A. Tok;Y. Sakka;H. Borodianska
中科院分区：
文献类型：
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作者：
O. Vasylkiv;D. Demirskyi;P. Badica;T. Nishimura;A. Tok;Y. Sakka;H. Borodianska
在 Ar 或 N2 气氛中通过火花等离子烧结 (SPS) 制备的致密 (95–98.6%) 块状碳化硼在室温和 1600 °C 下进行了三点弯曲测试。通过 SPS 对市售 B4C 粉末使用八种不同的固结条件。所得样品具有相似的晶粒尺寸，不超过 4 µm，室温弯曲强度 (σ25 °C) 为 300–600 MPa，表明 σ25 °C 的差异是由于 SPS 加工过程中整体碳化硼陶瓷中二次相的形成所致。为了解释这种差异，通过 XRD 和拉曼光谱观察到碳化硼和第二相的组成。碳化硼 490 cm−1 处拉曼峰强度的变化表明碳化硼成分发生了变化，较高的强度与较高的室温弯曲强度 (σ25 °C) 和维氏硬度 (HV) 相关。第二相可以改变一些不依赖于添加剂（有一些例外）或技术的总体趋势内的机械特性水平。即，当断裂韧性（KIC）较高时，HV增加，σ25°C降低，且比值σ1600°C/σ25°C（σ1600°C-1600°C弯曲强度）较低。 σ1600°C/σ25°C 的比值显示了两个低 KIC 区域和高 KIC 区域，由 KIC=4.1 MPa m0.5 界定：在低 KIC 区域，碳化硼样品是在氮气中生产的。
Dense (95–98.6%) bulk boron carbide prepared by Spark Plasma Sintering (SPS) in Ar or N2atmospheres were subject to three-point flexural tests at room and at 1600 °C. Eight different consolidation conditions were used via SPS of commercially available B4C powder. Resulting specimens had similar grain size not exceeding 4 µm and room-temperature bending strength (σ25 °C) of 300–600 MPa, suggesting that difference inσ25 °Cis due to development of secondary phases in monolithic boron carbide ceramics during SPS processing. To explain such difference the composition of boron carbide and secondary phases observed by XRD and Raman spectroscopy. The variation in intensity of the Raman peak at 490 cm−1of boron carbide suggests modification of the boron carbide composition and a higher intensity correlates with a higher room-temperature bending strength (σ25 °C) and Vickers hardness (HV). Secondary phases can modify the level of mechanical characteristics within some general trends that are not dependent on additives (with some exceptions) or technologies. Namely, HV increases,σ25 °Cdecreases, and the ratioσ1600 °C/σ25 °C(σ1600 °C– bending strength at 1600 °C) is lower when fracture toughness (KIC) is higher. The ratioσ1600 °C/σ25 °Cshows two regions of low and highKICdelimited byKIC=4.1 MPa m0.5: in the lowKICregion, boron carbide specimens are produced in nitrogen.