High‐temperature strength of liquid‐phase‐sintered silicon carbide ceramics: A review

Abstract

Silicon carbide (SiC) is a promising ceramic material for high-temperature structural applications, owing to its high flexural strength and room temperature (RT) strength retention ability at elevated temperatures (≥1400°C). This study reviews the influence of critical factors (grain-boundary structure, additive composition, additive content, microstructure, and testing atmosphere) on the RT strength retention at high temperatures and the high-temperature strength of LPS-SiC ceramics. The review suggests that (1) the minimization of additive content and careful selection of additive composition are crucial for achieving high flexural strength and excellent RT strength retention at ≥1500°C, and (2) additive compositions without Al compounds exhibit great potential to achieve excellent RT strength retention at ≥1500°C.

Low‐temperature Pr3Si2C2‐assisted liquid‐phase sintering of SiC with improved thermal conductivity

“…Therefore, it is a widely used method for the fabrication of SiC and SiC‐based ceramic matrix composites 6 . However, even though the liquid‐phase sintering additives are employed, sintering temperatures in the range of 1700–2100°C are usually required to consolidate SiC ceramics to near fully density 6,16 . On the other hand, the mechanical properties of SiC fibers are significantly deteriorated at temperatures above 1500°C, due to the grain growth of SiC fibers 25–27 .…”

“…7 Therefore, various sintering additives have been employed to improve consolidation of SiC, including both the solid-state sintering additives, such as B 4 C-C, B-C, and Al-B-C, [8][9][10] and the liquid-phase sintering additives, such as Al 2 O 3 , AlN, and rare-earth oxides (RE 2 O 3 ). [11][12][13][14][15][16][17] Liquid-phase sintering additives have been proven to be more efficient, due to a significantly higher diffusion rate of atoms achieved in a liquid when compared to a solid.…”

“…6 However, even though the liquid-phase sintering additives are employed, sintering temperatures in the range of 1700-2100 • C are usually required to consolidate SiC ceramics to near fully density. 6,16 On the other hand, the mechanical properties of SiC fibers are significantly deteriorated at temperatures above 1500 • C, due to the grain growth of SiC fibers. [25][26][27] Hence, the sintering temperature of SiC-based ceramic matrix composites should be as low as possible to inhibit the grain growth of SiC fibers.…”

Microstructural, electrical, and mechanical properties of conductive SiC ceramics fabricated by spark plasma sintering

“…[1][2][3] Owing to these advantages, SiC is one of the most important structural ceramics used in heat exchangers, gas turbine components, and accident-tolerant fuel cladding in light-water reactors. [4][5][6][7] However, conventional SiC ceramics have high electrical resistivity, hardness, and brittleness, which makes the processing of complex components difficult. Materials with low-electrical resistivity (<100 Ω cm) can be efficiently machined with high precision into complex surfaces through electric discharge machining (EDM).…”

In situ observation of evolution of internal structure of alumina during sintering by swept‐source OCT

“…Currently, most of the ceramics are produced by molding raw powder, followed by sintering. [1][2][3][4][5][6][7][8][9][10][11] During powder processing, sintering is caused via dynamic mass transfer, resulting in densification and microstructure development. Therefore, understanding and controlling sintering is extremely important for producing better ceramics.…”