Colloidal Processing of Complex-Shaped ZrB₂-Based Ultra-High-Temperature Ceramics: Progress and Prospects

Ultra-high-temperature ceramics (UHTCs), such as ZrB₂-based ceramics, are the most promising candidates for ultra-high-temperature applications. Due to their strong covalent bonding and low self-diffusion, ZrB₂-based UHTCs are always hot-pressed at temperatures above 1800 °C. However, the hot-pressing technique typically produces disks or cylindrical objects limiting to relatively simple geometrical and moderate sizes. Fabrication of complex-shaped ZrB₂-based UHTC components requires colloidal techniques. This study reviews the suspension dispersion and colloidal processing of ZrB₂-based UHTCs. The most important issues during the colloidal processing of ZrB₂-based UHTCs are summarized, and an evaluation of colloidal processing methods of the ZrB₂-based UHTCs is provided. Gel-casting, a net or near-net colloidal processing technique, is believed to exhibit a great potential for the large-scale industrialization of ZrB₂-based UHTCs. In addition, additive manufacturing, also known as 3D printing, which has been drawing great attention recently, has a great potential in the manufacturing of ZrB₂-based UHTC components in the future.