A computational analysis of a ZrO2–SiO2 scale for a ZrB2–ZrC–Zr ultrahigh temperature ceramic composite system

Reactive Processing of a ZrB2/ZrC/Zr–Si Ceramic Composite with a Controlled Oxygen Potential

“…A silica layer forming around a liquid Zr silicide can protect it from oxidizing fully in air to ZrO 2 and SiO 2 for 44 h at 1973 K and 49 h at 2273 K, as reported, respectively, by Petla et al . and Peña, Ramos and Bronson .…”

“…The silica layer also serves as an oxygen barrier during oxidation, although SiO 2 vaporization through SiO(g) limits its usefulness at temperatures >1700°C, as explained by Opeka et al, 4 Jacobson 14 and Bronson and Chessa. 15 A silica layer forming around a liquid Zr silicide can protect it from oxidizing fully in air to ZrO 2 and SiO 2 for 44 h at 1973 K and 49 h at 2273 K, as reported, respectively, by Petla et al 13 and Peña, Ramos and Bronson. 16 The formation of three phases consisting of SiO 2 , ZrO 2 , and Zr-Si liquid maintained the oxygen potential at~10 À16.5 atm at 1973 K along the internal wall of the SiO 2 layer.…”

“…The Zr–Si liquid was intended for the ultimate development of a dual‐layer scale consisting of SiO 2 and ZrO 2 , similar to the protective layers for the ZrB 2 –SiC system, as explained by Tripp, Davis and Graham, Rezale, Fahrenholtz and Hilmas, and Petla et al . . The liquid silicate‐boria layer seals any pores or cracks developed on the ZrB 2 –SiC scale at temperatures >1200°C.…”

“…The Zr-Si liquid was intended for the ultimate development of a dual-layer scale consisting of SiO 2 and ZrO 2 , similar to the protective layers for the ZrB 2 -SiC system, as explained by Tripp, Davis and Graham, 11 Rezale, Fahrenholtz and Hilmas, 12 and Petla et al. 13 The liquid silicate-boria layer seals any pores or cracks developed on the ZrB 2 -SiC scale at temperatures >1200°C. The silica layer also serves as an oxygen barrier during oxidation, although SiO 2 vaporization through SiO(g) limits its usefulness at temperatures >1700°C, as explained by Opeka et al, 4 Jacobson 14 and Bronson and Chessa.…”

The Temperature‐Dependent Ideal Tensile Strength of ZrB2, HfB2, and TiB2

“…Precise knowledge of the temperature‐dependent single‐crystal properties is not only required for the continuum‐based simulations of mesoscale features, but it is also important for the high‐temperature structural applications . The hardness, elastic constants, and thermal expansion at elevated temperatures of some single crystals of the AlB 2 ‐like diborides were investigated.…”