Phase constitutions of Mo‒Si‒N anti-oxidation multi-layer coatings on C‒C composites by fused slurry

To improve the oxidation resistance of Mo{single bond}Si fused slurry coating fabricated in vacuum, Mo{single bond}Si{single bond}N multi-layer coatings were synthesized on C/C composites in nitrogen atmosphere by fused slurry using same Mo and Si element powders. The phase compositions and microstructures were characterized by X-ray diffractometry (XRD), optical microscopy (OM), scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS). The results indicate that the Mo{single bond}Si{single bond}N coating contains SiC inner layer and MoSi₂/Si main layer, which was similar with Mo{single bond}Si coating. Additionally, a thin outer layer with nano-filiform morphology has been found on the coating surface, which consists of SiC, Si₃N₄, AlN, Al₂O₃ and sialon phase. Oxidation experiments show that the Mo{single bond}Si{single bond}N multi-layer coating exhibits excellent oxidation resistance at 1400 °C and anti-oxidizing potential ability at 1450 °C.