Tensile Properties and Microstructural Evolution of SiC Fibres from Room Temperature to 2000 ℃

doi:10.15541/jim20260075

Abstract

Abstract:

Continuous silicon carbide (SiC) ceramic fibres serve as reinforcements for composites used in aerospace and advanced nuclear energy applications. High-temperature tensile performance is a key property for ceramic fibres employed in extreme environments. However, reports on the in-situ high-temperature tensile properties of SiC fibres remain limited. In this study, in-situ high-temperature tensile tests using both cold-grip and hot-grip methods were employed to systematically investigate the relationships among composition, microstructure, and mechanical properties of SiC fibres from room temperature up to 2000 ℃ under different atmospheres. The high-temperature tensile strength of fibre tows is influenced by the atmosphere. At 1200 ℃, oxidation in air causes the tensile strength to decrease from 1632 MPa at room-temperature value to 417 MPa, retaining 44.4% of the original strength. In contrast, in an argon atmosphere at the same temperature, the tensile strength is 843 MPa, corresponding to a retention of 89.7%. In an argon atmosphere, the tensile strength retentions at 1400 and 1600 ℃ are 76.1% and 63.5%, respectively. Above 1700 ℃, the tensile strength decreases significantly, owing to rapid coarsening of β-SiC grains and the formation of pore defects from the decomposition of some amorphous phases. At 2000 ℃, the fibre strength drops to only 331 MPa, retaining only 22.5% of its original strength. This study reveals that SiC fibres exhibit relatively high strength retention in argon below 1600 ℃, and elucidates the mechanisms governing the evolution of high-temperature mechanical properties above 1700 ℃, including grain coarsening, partial phase decomposition and phase transformation. Therefore, this study provides critical fundamental data to support the high-temperature engineering application of domestic SiC fibres.

Key words: silicon carbide fibre, in-situ high-temperature tensile strength, tensile property, microstructure, grain coarsening

CLC Number:

TQ343

HE Tao, WANG Xingang, WANG Xiaofei, WANG Ming, XU Jingcheng, LÜ Songze, CHEN Yue, LIU Chenyu, JIANG Danyu. Tensile Properties and Microstructural Evolution of SiC Fibres from Room Temperature to 2000 ℃[J]. Journal of Inorganic Materials, 2026, 41(10): 1415-1424.

Figures/Tables 14

Table 1 Basic properties of Cansas-III silicon carbide fibre tows

Fibre	Filament diameter/ μm	Density/ (g·cm^-3)	Linear density/ tex	Tensile strength/ GPa	Tensile modulus/ GPa	Fracture strain/ %
Cansas-III	12±1	3.01	178	4.28	375	1.13

Fig. 1 Schematic diagrams of high-temperature tensile test apparatus for fibres (a) Cold-end clamping method; (b) Hot-end clamping method

Fig. 2 Tensile properties of SiC fibre tows at different temperatures (25-1200 ℃) (a) Tensile strength; Tensile strength retention based on the strength at (b) room temperature (25 ℃) and (c) 800 ℃; (d) Elastic modulus

Fig. 3 XRD patterns of as-received fibres before and after tensile test under different atmospheres and temperatures

Fig. 4 SEM images of SiC fibres after tensile testing at different temperatures and atmospheres (a) As received; (b-e) Air: (b) 200, (c) 600, (d) 800 and (e) 1200 ℃; (f-i) Ar: (f) 200, (g) 600, (h) 800 and (i) 1200 ℃

Fig. 5 SEM images and EDS analysis of the fracture surface and surface of fibres (a, b) Fracture surface; (c) Surface; (d) Fracture surface from manual cutting

Fig. 6 Weibull parameter fitting curve of SiC single filaments

Table 2 Weibull parameters (${{m}_{\mathbf{s}}}$, ${{\sigma }_{0,s}}$), coefficient of determination (R2), statistical average strength ($\bar{\sigma }$), and mean strength (${{\bar{\sigma }}_{\mathbf{s}}}$) obtained by single filament tensile test

Fibre	${{m}_{\text{s}}}$	σ_0,s/GPa	R²	σ¯/GPa	σ¯_s/GPa
Cansas-III	6.7	4.2	0.97	3.9	4.1

Table 3 Comparison of the Weibull parameters obtained from the tensile tests of SiC filaments and tows

Fibre	${{m}_{\text{s}}}$	${{m}_{\text{tow}}}$	${{\sigma }_{0,\text{s}}}$/GPa	${{\sigma }_{0,\text{tow}(\text{GL}=25)}}$/GPa
Cansas-III	6.7	6.3	4.2	3.3

Fig. 7 (a) Tensile strength and (b) strength retention of SiC fibre tows at different temperatures by hot-end gripped method

Fig. 8 (a) Force-displacement curves of SiC fibre tows at different temperatures; (b) Room-temperature tensile strength of sizing-removed fibre tows at different gauge lengths Colorful figures are available on website

Fig. 9 (a) XRD patterns and (b) grain size of SiC fibres after tensile test at different temperatures by hot-end gripped method

Fig. 10 SEM images of SiC fibres after tensile test at 1400-2000 ℃ by hot-end gripped method (a) 1400 ℃; (b) 1700 ℃; (c) 1800 ℃; (d) 2000 ℃

Fig. 11 (a, c) TEM and (b, d) high resolution TEM images of SiC fibres after high-temperature tensile test (a, b) 1200 ℃; (c, d) 2000 ℃

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