Processing, Characterization, and Thermomechanical Performance of YSZ/SiCN Ceramic Matrix Composites Under Hydrogen Combustion

Ceramic matrix composites (CMCs) are promising thermal-protection materials for hydrogen-fueled gas turbines, where components are exposed to high temperatures, steam-rich combustion products, and pressure-driven heat transfer. This study investigates yttria-stabilized zirconia (YSZ) fiber-reinforced polymer-derived ceramic composites fabricated by polymer infiltration and pyrolysis (PIP) using Durazane-1800 as the preceramic precursor. Eight-layer YSZ preforms were rigidized, vacuum-infiltrated, cured, and pyrolyzed at 950 °C in nitrogen; repeated PIP cycles were used to increase matrix densification. Under hydrogen torch exposure at a heat flux of 180–190 W/cm2, the front-face temperature of the CMC coupon reached approximately 1400 °C while the back-face temperature stabilized near 600 °C during a 10 min test, with no observed delamination or burn-through. Post-test SEM/EDS and XRD characterization indicated oxidation of the SiCN matrix and the deposition of a silica-rich substance on the material surface. In a hydrogen-combustion rig, the CMC liner reduced the external wall temperature relative to the unlined wall by approximately 32 °C at 1 atm and 17 °C at 5 atm. Transient thermal simulations reproduced the measured temperature trends with differences of approximately 3.8–7.8% for selected temperatures at 1 atm and 6.2% for the liner back-face temperature at 5 atm. Increasing the number of PIP cycles from two to seven increased fracture strength from 7.87 to 19.77 MPa and flexural modulus from 4.05 to 24.34 GPa. These results demonstrate the potential of YSZ-reinforced polymer-derived CMCs as thermal barriers for hydrogen-combustion environments and identify porosity control as a key requirement for improved high-pressure performance.