In situ Formation of Oxidation Resistant Refractory Coatings on SiC ‐Reinforced ZrB 2 Ultra High Temperature Ceramics

In situ oxidation resistant and solid refractory coatings have been generated on 20 vol% SiC ‐reinforced ZrB 2 ultra high temperature ceramics containing 10 wt% rare earth ( RE ) additives such as LaB 6 , La 2 O 3 , and Gd 2 O 3 fabricated by spark plasma sintering. Oxidation for 1 h at 1600°C in static air led to formation of a dense layer (up to 250 μm thick) of ZrO 2 and RE ‐zirconates on the composite systems underneath which were intermediate layers (50–100 μm) containing heterogeneous crystalline oxides such as La 2 Zr 2 O 7 and amorphous silicate phases. The benefits of predominating solid oxidation products over having substantial volumes of liquid present in aerospace leading edge applications are discussed.