Advances in ultra-high temperature ceramics, composites, and coatings

Abstract

Ultra-high temperature ceramics (UHTCs) are generally referred to the carbides, nitrides, and borides of the transition metals, with the Group IVB compounds (Zr & Hf) and TaC as the main focus. The UHTCs are endowed with ultra-high melting points, excellent mechanical properties, and ablation resistance at elevated temperatures. These unique combinations of properties make them promising materials for extremely environmental structural applications in rocket and hypersonic vehicles, particularly nozzles, leading edges, and engine components, etc. In addition to bulk UHTCs, UHTC coatings and fiber reinforced UHTC composites are extensively developed and applied to avoid the intrinsic brittleness and poor thermal shock resistance of bulk ceramics. Recently, highentropy UHTCs are developed rapidly and attract a lot of attention as an emerging direction for ultra-high temperature materials. This review presents the state of the art of processing approaches, microstructure design and properties of UHTCs from bulk materials to composites and coatings, as well as the future directions.

Equiatomic 9-cation high-entropy carbide ceramics of the IVB, VB, and VIB groups and thermodynamic analysis of the sintering process

“…Since bulk high-entropy (HE) oxide ceramics were first reported in 2015 [1], the HE ceramics have become a new family of advanced ceramics [2][3][4]. HE nonoxide ceramics are important branches of the HE ceramic family and have received extensive research in recent years.…”

High-aspect-ratio single-crystalline (HfxZr(1−x))B2 micron-rods: low-temperature, highly-efficient synthesis and oriented growth mechanism

“…In recent decades, IVB–VIB transition-metal diborides (termed TMB 2 ), as representative members in the family of ultra-high-temperature ceramics (UHTCs), were regarded as the most promising candidates for versatile high-temperature structural applications including the nozzles and leading edges of hypersonic and reentry vehicles, owing to their ideal combination of high melting point, excellent ablation resistance, high hardness, good erosion resistance, high specific strength/stiffness, etc. 1,2 However, UHTCs also suffered from the performance shortcomings of low high-temperature oxidation resistance, moderate toughness and the resulting poor thermal shock resistance, 3,4 which severely restricted their broader application.…”

Recent Progress in 1D Nanostructures Reinforced Carbon/Carbon Composites

“…Owning to the excellent structural advantages and superior properties, such as low density (<2.0 g cm -3 ), high specific strength and modulus, low coefficient of thermal expansion (CTE), high thermal conductivity, high mechanical properties retention at high temperatures in inert environment, and good friction/ wear properties, carbon fiber reinforced carbon matrix (carbon/carbon, C/C) composites are considered to be one of the most promising ultrahigh temperature thermal protection structural materials, which are widely applied in the aviation, aerospace, and some civil fields. [1][2][3][4][5] With the rapid development of aerospace vehicles and the complexity of service environ ment, it is urgent to develop new generation of C/C composites with the greatly improved performance and integrated multifunctions. [6][7][8][9][10][11][12] For example, for traditional C/C composites, carbon matrix is strengthened by carbon fibers in macroscale, but carbon matrix between carbon fiber bundles and between carbon fibers in bundle cannot be effectively strengthened in nanoscale.…”

“…Owning to the excellent structural advantages and superior properties, such as low density (<2.0 g cm –3 ), high specific strength and modulus, low coefficient of thermal expansion (CTE), high thermal conductivity, high mechanical properties retention at high temperatures in inert environment, and good friction/wear properties, carbon fiber reinforced carbon matrix (carbon/carbon, C/C) composites are considered to be one of the most promising ultrahigh temperature thermal protection structural materials, which are widely applied in the aviation, aerospace, and some civil fields. [ 1–5 ]…”