Oxidation and cracking resistances of La2O3 modified ZrB2–SiC coating on SiC coated graphite in static air

A La2O3 modified ZrB2–SiC coating on SiC coated graphite was prepared by slurry brushing and subsequent siliconizing. The coating exhibited much better oxidation and cracking resistances compared with ZrB2–SiC coating. The weight gain of ZrB2–SiC–La2O3 coated sample was 3.85 × 10−3 g/cm2 after isothermal oxidation at 1800 °C for 30 min and it was 6.49 × 10−3 g/cm2 after short cyclic oxidation at 1500 °C for 30 times, while they were 4.25 × 10−3 g/cm2 and -7.12 × 10−3 g/cm2 for the ZrB2–SiC coated sample, respectively. The good comprehensive performance of La2O3 modified ZrB2–SiC coating was attributed to the continuous La dissolved oxide scale with lower oxygen permeability and lower internal stress. •La2O3 modified ZrB2–SiC coating was prepared by slurry brushing and siliconizing.•ZrB2–SiC–La2O3 coating showed excellent anti-oxidation properties at 1800 °C.•ZrB2–SiC–La2O3 coating exhibited excellent cracking resistance.•The oxidation and cracking processes of the coatings were discussed in detail.