HfC-HfO2-SiO2 nanocomposite ceramic coating formed on TiAlNb medium-entropy alloy by LPDS: Microstructure evolution and ablation behavior

HfC-HfO2-SiO2 nanocomposite ceramic coating was prepared on the TiAlNb medium-entropy alloy by a novel one-step liquid plasma-assisted particle deposition sintering (LPDS) method to improve the ablation resistance. Meanwhile, PEO coatings were prepared as a comparison at different voltages (400 V, 450 V, 500 V). When the PEO coating fabricated at 500 V was ablated for 360 s, the peeling area was the largest at 41.05 %, which was 2.3 times larger than the PEO coating (400 V, 18.03 %). However, the HfC-HfO2-SiO2 nanocomposite coating exhibits no surface peeling. The surface particles of the coating were sintered together, reducing the presence of pores and enhancing the structure density. Additionally, a large amount of HfO2 and stable HfSiO4 particles were embedded in the amorphous SiO2 layer, which improved the melting point and stability of the glass layer while reducing oxygen permeability. The formed HfSiO4 after ablation acted as "nails", effectively suppressing the generation of cracks.