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.