Microstructural evolution and performance of carbon fiber-toughened ZrB2 ceramics with SiC or ZrSi2 additive

Abstract

ZrB 2 -SiC/ZrSi 2 ceramics containing 30 vol% carbon fiber (C f ) additive were fabricated by hot pressing at low temperature (1500 ℃) using submicron ZrB 2 powders, and their microstructural evolution and performance were investigated. The addition of SiC or ZrSi 2 significantly reduced the onset sintering temperature and enhanced the densification of ZrB 2 . ZrB 2 -ZrSi 2 -C f showed poor performance owing to the serious fiber degradation, while the fiber degradation was effectively inhibited in ZrB 2 -SiC-C f resulting in high fracture toughness, substantial fiber pull-out, and non-brittle fracture mode for such material. The critical thermal shock temperature difference of ZrB 2 -SiC-C f was up to 741 ℃, significantly higher than those of ZrB 2 -SiC/ZrSi 2 and ZrB 2 -ZrSi 2 -C f . Moreover, this composite displayed a good oxidation resistance at 1500 ℃ in air.

Investigation on microstructure and mechanical properties of short-carbon-fiber/Ti3SiC2 composites

“…Additionally, the length of C sf in the Ti 3 SiC 2 matrix was apparently shorter than their original length (3-5 mm). The reduction in C sf length is caused by the applied pressure during sintering process or C sf might hide in the inner of the samples [23]. And, no pores were found in these composites, indicating that the well dispersed C sf could promote the densi cation of Ti 3 SiC 2 matrix.…”

Sol-gel derived porous ultra-high temperature ceramics

“…Ultra-high temperature ceramics (UHTCs) are a class of nonmetallic and inorganic materials that have melting point over 3000 ℃ and are typically borides, carbides, and nitrides of early transition metals (e.g., Zr, Hf, Nb, Ta) [1][2][3][4][5][6][7][8]. Due to the combination of series of excellent physical and chemical properties, such as high hardness, good high-temperature stability, and excellent solid-phase stability, UHTCs are considered as promising candidate materials for high-temperature structural applications, including engines, hypersonic vehicles, plasma arc electrode, cutting tools, furnace elements, and high-temperature shielding [7,[9][10][11][12][13]. UHTCs are difficult to densify without sintering additives and external pressure.…”

Molten salt synthesis, formation mechanism, and oxidation behavior of nanocrystalline HfB2 powders

“…As members of ultra-high temperature ceramics, transition-metal borides (TMB 2 ) ceramics have attracted considerable attentions for potential applications in aircraft, atomic, and astronautic manufacturing industries, since they exhibit high melting point, high hardness, high thermal conductivity, and excellent chemical stability [1][2][3]. The synthesis of TMB 2 powders is critical for implementing their extensive applications.…”