Effect of Argon Atmosphere Heat Treatment on Mechanical Properties and Microstructural Evolution of Shicolon-II SiC Fibers

doi:10.15541/jim20250052

Abstract

Abstract:

Silicon carbide fibers are considered ideal reinforcing materials for ceramic matrix composites due to their excellent mechanical properties and high-temperature performance. Different types of fibers necessitate individual investigation due to variations in their composition and fabrication processes. This study presents a comprehensive investigation into evolution of the mechanical properties, surface microstructure, and composition of Shicolon-II fibers subjected to argon heat treatment at temperatures ranging from 1300 ℃ to 1700 ℃. The Shicolon-II fibers are composed of small-sized β-SiC grains, SiC_xO_y amorphous phase, and a minor amount of graphite microcrystals. Following treatment in an argon atmosphere at 1300 ℃, the fibers maintain a monofilament tensile strength of 3.620 GPa, corresponding to a retention of 98.32%. This strength diminishes to 2.875 GPa, equating to a retention of 78.08%, after treatment at 1500 ℃. The reduction in mechanical properties of the fibers can be ascribed to the decomposition of the amorphous phase and the growth of β-SiC grains. Furthermore, creep resistance is an essential factor influencing the long-term performance of composite materials. After treatment at temperatures above 1400 ℃, the high-temperature creep resistance of the fibers is significantly enhanced due to growth of β-SiC grains. This study offers valuable theoretical insights into high-temperature applications of second-generation fibers, contributing to an enhanced understanding of their performance under extreme conditions.

Key words: Shicolon-II SiC fiber, heat treatment, mechanical property, microstructure

CLC Number:

TQ343

YUAN Wang, HU Jianbao, ZHOU Liang, KAN Yanmei, ZHANG Xiangyu, DONG Shaoming. Effect of Argon Atmosphere Heat Treatment on Mechanical Properties and Microstructural Evolution of Shicolon-II SiC Fibers[J]. Journal of Inorganic Materials, 2026, 41(1): 119-128.

Figures/Tables 11

Table 1 Relevant parameters of Shincolon-II SiC fibers

Fiber	Diameter/μm	C/Si	Oxygen/% (in atom)	Young's modulus/GPa	Average tensile strength/GPa
Shincolon-II	8.1±1.0	1.46	1.4	326.6	3.682

Fig. 1 Average monofilament tensile strengths (a) and Weibull plots (b) of the fibers

Fig. 2 Fiber wrapping schematic (a) and bend stress relaxation results of fibers (b)

Fig. 3 (a) Stress relaxation ratio of heat-treated fibers at different test temperature; (b) β-SiC grain size and 1400 ℃ BSR results of different heat-treated fibers

Fig. 4 TEM and HRTEM images of as-received fiber (a, b), fiber after heat treatment at 1500 ℃ (c, d), and corresponding SAED images (insets in (a, c))

Fig. 5 XRD patterns of Shicolon-II SiC fibers after argon treatment at different temperatures (a) and size of β-SiC crystallites versus heat treatment temperature (b)

Fig. 6 Morphologies of Shicolon-II SiC fibers after heat treatment at different temperatures

Fig. 7 Cross-sectional morphologies of Shicolon-II SiC fibers after heat treatment at different temperatures

Fig. 8 Full and fine XPS spectra of Shicolon-II SiC fibers (a, b) As-received fiber; (c, d) Fiber after heat treatment at 1500 ℃

Fig. 9 AES results of Shicolon-II SiC fibers (a) As-received fiber; (b) Fiber after heat treatment at 1400 ℃

Fig. 10 Raman spectra of heat-treated fibers (a) and ID/IG values after heat treatment at different temperatures (b)

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