Zirconium diboride based ceramics, owing to their superior high temperature properties are potential materials for use as leading edge components in hypersonic space vehicles. However, the difficulty in sintering these ultra high temperature ceramics limit their applications to some extent. Sintering of such materials is usually accomplished by resorting to advanced sintering techniques such as Spark Plasma Sintering (SPS) accompanied by sinter aids to improve the sinterability. In this backdrop, the current work investigates the effect of Ti addition on the mechanical properties and sinterability of ZrB 2 based ceramic composites. Tailored addition of Ti to ZrB 2 18 wt. % SiC baseline composites not only improves the densification but also increases hardness and indentation toughness, when sintered using Multi Stage Spark Plasma Sintering technique. Microstructure and X-ray diffraction analysis reveals the presence of ultrafine grains of ZrB 2 and SiC, which is found to be effective in obtaining a good hardness (up to 29 GPa) and reliable indentation toughness (up to 9 MPa•m 1/2).

Among ultra high temperature ceramics (UHTCs), ZrB 2 -based ceramics have received the most attention for applications in hypersonic space vehicles. However, UHTCs encounter several challenges pertaining to their processing to achieve the desired properties in order to optimally exploit their potential. In this perspective, the present work illustrates some of the sintering related challenges using a case study of ZrB 2 -SiC based ceramics. Multi stage spark plasma sintering is carried out on ZrB 2 -SiC based ceramics at 1500°C with metallic Titanium as sinter-aid. High hardness of up to 28 GPa is obtained in dense ceramics with finer microstructure. Furthering towards design and fabrication of real scale hypersonic application such as thermal protection system, efforts have been taken to prove the scalability of the ceramics by consolidating up to w100 mm ceramic discs.

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