4D C/SiC composite nozzle was fabricated using LSI and characterized for mechanical, thermal, and ablation properties. Average flexural and compressive strengths in the Z-direction were found to be 119 and 110 MPa, while in the U-, V-and W-directions, they were 99 and 55MPa, respectively. Coefficient of thermal expansion was found to be varied in the range 0-1.5 9 10 À6 /°C (25-1050°C), while thermal diffusivity was 40-5 mm 2 /s (25-1200°C). Ablation behavior of the nozzle was evaluated under UH25/N 2 O 4 propulsion system for 30 s. The overall mass erosion rate and the linear ablation rate were found to be 0.119 kg/m 2 s and 0.05 mm/s, respectively.