Infiltration Behavior of the Molten Ca33Mg9Al13Si45 Layer on SiCf/SiC Under Air and Water-Vapor Conditions at 1300 °C

In this study, the Ca33Mg9Al13Si45 layer was fabricated on the SiCf/SiC surface by APS to simulate the coexistence of high-velocity impact and molten-state deposition. Subsequently, the corrosion and infiltration behaviors of the molten Ca33Mg9Al13Si45 in air and water-vapor environments (H2O:O2 = 90:10 vol%) at 1300 °C for 300 h were investigated. The results indicated that, during corrosion, the molten Ca33Mg9Al13Si45 infiltrated into the interior of the SiCf/SiC through interconnected pores. Under high-temperature air corrosion, Ca and Mg remained restricted to the upper-part pore-filling region. Compared with high-temperature air corrosion, Ca and Mg infiltrated deeper along the pores into the interior of the SiCf/SiC under high-temperature water-vapor corrosion. Once the molten Ca33Mg9Al13Si45 filled these pores, no obvious elemental diffusion or further infiltration was detected at the interface between the molten Ca33Mg9Al13Si45 and SiCf/SiC, suggesting good interfacial chemical stability. The flexural strength of the original SiCf/SiC was 445 ± 43 MPa, while the SiCf/SiC with the molten Ca33Mg9Al13Si45 after high-temperature air corrosion and water-vapor corrosion exhibited flexural strengths of 409 ± 30 MPa and 440 ± 33 MPa. These results demonstrated that the infiltration behavior of the molten Ca33Mg9Al13Si45 had a relatively minor impact on the mechanical behavior of SiCf/SiC, enabling the materials to retain mechanical performance close to the original level after high-temperature exposure.