Experimental investigation of the evolution of pore structures and seepage characteristics of 2D plain-woven ceramic matrix composites under high-temperature environments

Ceramic matrix composites are lightweight, high-temperature-resistant porous materials with wide applications in thermal protection under high-temperature and high-heat-flux environments in aerospace. Utilizing their in-situ woven pores for transpiration cooling is an effective method for thermal protection of aero-engine hot-section components. However, the evolution of internal pores under high-temperature conditions remains unclear. In this study, CT was employed to characterize the internal pore structures of C/SiC ceramic matrix composites fabricated from woven preforms. Pore models were established based on CT results at four temperatures (25 °C, 400 °C, 700 °C, and 900 °C), revealing pore evolution during heating and elucidating the evolution of internal pore morphology and porosity of the porous medium. On this basis, this study developed modified ceramic matrix composites suitable for high-temperature transpiration cooling applications by adjusting weaving parameters. Transpiration seepage tests were conducted at flow rates ranging from 0 to 35 Nm 3 /h, and the permeability and inertial constant were calculated based on curves fitted using the Darcy-Forchheimer equation. Experimental results indicate that the modified material exhibits seepage properties similar to those of sintered metal porous media. This study is of scientific significance for clarifying seepage and transpiration cooling mechanisms and provides guidance for the development of transpiration cooling technology.