Effect of powder pre-oxidation on the microstructure and ablation resistance of ZrB₂–SiC coating

To further improve the densification and properties of ZrB₂–SiC coating, the ZrB₂–SiC powder was pre-oxidized at different temperatures before plasma spraying. And the ablation property of the obtained coatings were assessed using an oxyacetylene torch flame. A core-shell structure powder was obtained after the pre-oxidation treatment at 800 °C. And the oxidized shell was dense and integral with an uniform thickness. Compared with the IPS-coating, the porosity percent of the corresponding pre-oxidized coating showing a classical lamellar structure decreased from 12.7% to 8.8%. The pre-oxidized coating showed a dense ZrO₂ surface with a honeycomb-structure after ablation at 1800 °C for 60s.