Open Access Research Article Issue
Oxidation behaviors of carbon fiber reinforced multilayer SiC-Si3N4 matrix composites
Journal of Advanced Ceramics 2022, 11 (2): 354-364
Published: 11 January 2022

Oxidation behaviors of carbon fiber reinforced SiC matrix composites (C/SiC) are one of the most noteworthy properties. For C/SiC, the oxidation behavior was controlled by matrix microcracks caused by the mismatch of coefficients of thermal expansion (CTEs) and elastic modulus between carbon fiber and SiC matrix. In order to improve the oxidation resistance, multilayer SiC-Si3N4 matrices were fabricated by chemical vapor infiltration (CVI) to alleviate the above two kinds of mismatch and change the local stress distribution. For the oxidation of C/SiC with multilayer matrices, matrix microcracks would be deflected at the transition layer between different layers of multilayer SiC-Si3N4 matrix to lengthen the oxygen diffusion channels, thereby improving the oxidation resistance of C/SiC, especially at 800 and 1000 ℃. The strength retention ratio was increased from 61.9% (C/SiC-SiC/SiC) to 75.7% (C/SiC-Si3N4/SiC/SiC) and 67.8% (C/SiC-SiC/Si3N4/SiC) after oxidation at 800 ℃ for 10 h.

Open Access Research Article Issue
Microstructure and mechanical properties of Zr3Al3C5-based ceramics synthesized by Al–Si melt infiltration
Journal of Advanced Ceramics 2021, 10 (3): 529-536
Published: 15 April 2021

In this work, bulk Zr3Al3C5-based ceramics were synthesized by the infiltration of Al–Si melt into zirconium carbide (ZrC) perform. The phase composition, microstructure, and mechanical properties of as-fabricated ceramics were studied. The results demonstrate that Si is more effective to reduce the twin boundary energy of ZrC than Al, and thus promotes the decrease of formation temperature of Zr3Al3C5. With the infiltration temperatures increasing from 1200 to 1500 ℃, the Zr3Al3C5 content increases from 10 to 49 vol%, which is contributed to the increase of flexural strength from 62±9 to 222±10 MPa, and fracture toughness (KIC) from 2.8±0.2 to 4.1±0.3 MPa·m1/2. The decrease of mechanical properties for the samples fabricated at 1600 ℃ is ascribed to the abnormal growth of Zr3Al3C5 grains.

Open Access Research Article Issue
Effect of pyrolytic carbon interphase on mechanical properties of mini T800-C/SiC composites
Journal of Advanced Ceramics 2021, 10 (2): 219-226
Published: 27 February 2021

The effect of pyrolytic carbon (PyC) thickness on the tensile property of mini T800 carbon fiber reinforced SiC matrix composites (C/SiC) was studied. PyC interphase was prepared by chemical vapor infiltration (CVI) process using C3H6-Ar as gas source, the PyC thickness was adjusted from 0 to 400 nm, and then the SiC matrix was prepared by CVI process using methyltrichlorosilane (MTS)-H2-Ar as precursor and gas source. The results showed that the tensile strength of mini T800-C/SiC increased first and then decreased with the increase of the PyC thickness. When the thickness of PyC was 100 nm, the average strength reached the maximum value of 393 ± 70 MPa. The Weibull modulus increased from 2.0 to 8.06 with the increase of PyC thickness, and the larger the Weibull modulus, the smaller the dispersion, which indicated that the regulation of PyC thickness was conducive to improve tensile properties.

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