High-temperature performances of Si-HfO2-based environmental barrier coatings via atmospheric plasma spraying

To improve high-temperature bearing capability of coatings, novel agglomerated Si-HfO2 powders were prepared by adding HfO2 powders into original Si powders by spray drying method. Three-layer environmental barrier coatings (EBCs) with Si-HfO2 bond layer, Yb2Si2O7 intermediate layer and Yb2SiO5 surface layer were prepared on SiC ceramic substrates by atmospheric plasma spraying (APS). The high temperature properties of coatings were systematically investigated. The results indicated that the coatings had good high temperature oxidation resistance, and remained intact after being oxidized or steam corrosion at 1400 °C for 500 h, so the addition of HfO2 improved the thermal cycling performances of the coating. The HfO2 in Si bond coating could effectively inhibit the growth of thermal grown oxide at high temperatures. This work indicates that the high temperature properties of the coatings are improved by this novel EBCs using the novel agglomerated Si-HfO2 powders.