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<p>SiC<sub>f</sub>/SiC composites were fabricated by a novel two-stage precursor infiltration and pyrolysis (PIP) process. The two types of SiC fibers (C3-BN and C3-BN-1800) were used as reinforcements. The C3-BN was the third-generation SiC fibers coated with an in-situ boron nitride (BN) layer, C3-BN-1800 was obtained by a 1&#xa0;min continuous pyrolysis of C3-BN at 1800&#xa0;°C. In stage I, the SiC<sub>f</sub>/SiC composites (CMC-Is) achieved initial densification by low-temperature PIP process, while the matrix consisted of low crystallinity SiC and amorphous SiO<i>x</i>C<i>y</i>. At 1600&#xa0;°C-1&#xa0;h, the crystallization of SiC matrix and decomposition of SiO<i>x</i>C<i>y</i> led to a significant reduction in the strength of the CMC-Is (30% strength retention). Through several cycles of high-temperature PIP process (stage II), the SiC<sub>f</sub>/SiC composites (CMC-IIs) had higher density than CMC-Is, and the matrix had high crystallinity SiC and significantly decreased oxygen content. Thus the CMC-IIs have better thermal resistance and the strength retention is near 50% at 1600&#xa0;°C-10&#xa0;h.</p>

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Effects of in-situ BN coating on thermostructural properties of SiCf/SiC composites prepared via PIP process

  • 期刊论文

  • 发表日期：

    2025年4月1日

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  • Senyan Zheng,
  • Ying Liang,
  • Qi Wang,
  • Huibin Tu,
  • Lifu Chen,
  • Siwei Li

摘要

SiCf/SiC composites were fabricated by a novel two-stage precursor infiltration and pyrolysis (PIP) process. The two types of SiC fibers (C3-BN and C3-BN-1800) were used as reinforcements. The C3-BN was the third-generation SiC fibers coated with an in-situ boron nitride (BN) layer, C3-BN-1800 was obtained by a 1 min continuous pyrolysis of C3-BN at 1800 °C. In stage I, the SiCf/SiC composites (CMC-Is) achieved initial densification by low-temperature PIP process, while the matrix consisted of low crystallinity SiC and amorphous SiOxCy. At 1600 °C-1 h, the crystallization of SiC matrix and decomposition of SiOxCy led to a significant reduction in the strength of the CMC-Is (30% strength retention). Through several cycles of high-temperature PIP process (stage II), the SiCf/SiC composites (CMC-IIs) had higher density than CMC-Is, and the matrix had high crystallinity SiC and significantly decreased oxygen content. Thus the CMC-IIs have better thermal resistance and the strength retention is near 50% at 1600 °C-10 h.