An ultra-high temperature Mo-Si-B based coating for oxidation protection of NbSS/Nb5Si3 composites

A Mo-Si-B based coating was prepared on an NbSS/Nb5Si3 composite by a two-step process consisting of the initial deposition of Mo followed by pack cementation co-deposition of Si and B. After a conditioning treatment, an aluminoborosilica layer fully covered the sample. Following oxidation at 1300 °C for 24 h, the coated sample demonstrated a weight loss of about 0.55 mg/cm2 and the uncoated sample exhibited catastrophic oxidation with a weight gain of 87.6 mg/cm2. These results demonstrate that the Mo-Si-B based coating can enable the use of the NbSS/Nb5Si3 composites at temperature up to 1300 °C in an oxidizing environment.