High temperature oxidation behavior of liquid phases sintered SiC ceramics with ZrB 2 addition

The oxidation property of liquid-phase sintered silicon carbide (LPS-SiC) ceramics with ZrB 2 addition was studied after oxidation test in air at 1400 degrees C. The results indicate that the addition of ZrB 2 decreased the degree of polymerization (DOP) of the silicate networks in the oxide layer, suppressing the additional oxidation caused by residual bubbles in the oxide layer of LPS-SiC, which bypassed the layer and directly corroded the material internally. After 100 h of oxidation, the additional oxidation depth was found to be 125 mu m in the sample without ZrB 2 and 0 mu m in those containing 10 wt% ZrB 2 . Simultaneously, the decrease in DOP facilitates the migration of crystalline phases. The generated ZrSiO 4 can migrate and aggregate at the interface between the surface oxide layer and the SiC/ZrB 2 matrix, forming a continuous ZrSiO 4 barrier. This impedes the diffusion of the oxidant and enhances the oxidation resistance. However, an insufficient ZrB 2 content leads to a discontinuous ZrSiO 4 layer, thereby weakening its protective effect. Simultaneously, a decrease in DOP increases the rate of oxygen diffusion, resulting in an increase in the oxidation layer thickness. This study contributes to a better understanding of the failure mechanisms of LPS-SiC in oxidizing environments and provide a reference for the design of oxidationresistant LPS-SiC materials.