Silicon Nitride/Molybdenum Disilicide Composite with Superior Long‐Term Oxidation Resistance at 1500°C

The long‐term high‐temperature cyclic oxidation (100 cycles, 10 4 h, 1500°C) of a Si 3 N 4 material and a Si 3 N 4 /MoSi 2 composite, both fabricated with Y 2 O 3 as a sintering additive, was studied. Both materials exhibited similar oxidation rates because of surface SiO 2 formation described by an almost parabolic law and a total weight gain of 3–4 mg/cm 2 after 10 4 h. As a consequence of oxidation processes in the bulk, microstructural damage was found in the Si 3 N 4 material. These effects were not observed in the composite. The remarkable microstructural stability observed offers the high potential of Si 3 N 4 /MoSi 2 composites for long‐term structural applications at elevated temperatures up to 1500°C.