Composition design of transition metal diboride-based ultra-refractory ceramics containing SiC for extreme applications

MB2 with SiC additions (M= Zr, Hf, Ti) in various amount and shape (particulate, whisker, short fiber) is an emblematic example of composition design of materials which has captured the attention of the UHTC community. This class of composites brings efficiently together the combination of excellent mechanical properties and resistance to oxidation at very high temperature. The drive is indeed the need of leading edges for future hypersonic vehicles with sharp profile. Such passive components are subject to very stressful heat fluxes in corrosive plasmas from atmosphere, and temperatures above 2300K for several minutes may become a projected service condition. Actually, methods for enhancing the resistance to oxidation when the protection of external glassy silica-based films begins to fail are currently studied. Refractory carbides like B4C or WC are of great interest in relation to the multiple favorable effects they induce on densification and properties once added to MB2-SiC composites. Microstructure and key properties of hot-pressed ZrB2-SiC materials processed with the addition of third phases such WC and/or B4C were analyzed, and compared to other ZrB2-SiC doped with (limited content of) Si-bearing third phases. Resistance to oxidation in oxidizing furnaces was investigated and compared to that obtained by using an arc-jet testing facility