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

Dewei Ni,Ji-Xuan Liu,Hejun Li,Guo-Jun Zhang,Qiangang Fu,Shaoming Dong,Jiecai Han,Haoyang Wu,Ji Zou,Bowen Chen,Yuan Cheng,Xinghong Zhang,Jiaping Zhang

doi:10.1007/s40145-021-0550-6

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.

Highlights

Ultra-high temperature ceramics (UHTCs) refer to a number of special materials which are chemically stable at ultra-high temperatures and in reactive atmosphere, usually including borides, carbides, and nitrides of transition metals, and other high-melting point compounds [1–5]
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 strong covalent structure endows the UHTCs with ultra-high melting points, excellent mechanical properties, and ablation resistance at elevated temperatures

Summary

Introduction

Ultra-high temperature ceramics (UHTCs) refer to a number of special materials which are chemically stable at ultra-high temperatures (above 2000 °C) and in reactive atmosphere (i.e., atomic oxygen environment), usually including borides, carbides, and nitrides of transition metals, and other high-melting point compounds [1–5]. Compared with carbides or borides, the mechanical properties of nitride-based UHTCs are lower They normally possess high CTE (7×10–6–10×10–6 K–1) and low thermal conductivity (19–23 W·m–1·K–1). Continuous fiber-reinforced UHTC matrix composites (UHTCMCs) overcome the inherent brittleness and poor thermal shock resistance of bulk UHTCs [20–23]. (3) UHTC coatings An alternative approach to avoid the catastrophic failure of large monolithic UHTC component is to deposit them on tough and heat resistant substrates [36–42], i.e., carbon fiber-reinforced composites and graphite. By combining the progress on ceramics, composites, and coatings, this review tries to provide guidelines for the researchers to design, select, and manufacture suitable forms of ultra-high temperature materials for demanding environments

Bulk UHTCs

UHTC coatings

High-entropy UHTCs

Findings

Summary and outlook