A novel process for fabricating SiCf/SiC by liquid silicon infiltration using CVI-derived porous carbon in fiber preform

Abstract

This study introduces a novel process developed to minimize residual carbon and silicon in the SiC matrix of liquid silicon infiltrated SiC<inf>f</inf>/SiC (LSI-SiC<inf>f</inf>/SiC) by depositing porous carbon into a fiber preform via chemical vapor infiltration (CVI) process. The CVI process was conducted using acetylene gas at 1000–1200 °C for 5 h under 2.66 kPa. During deposition, both porous carbon and a dense carbon coating layer were simultaneously formed within the SiC fabrics. As the deposition temperature increased, the particle size of the porous carbon decreased and the formation of porous carbon was promoted, while the thickness of the dense carbon coating layer decreased. The LSI-SiC<inf>f</inf>/SiC fabricated with porous carbon deposited in SiC fabric at 1200 °C exhibited almost no residual carbon in the SiC matrix. The residual silicon content in the SiC matrix was 14 % and the LSI-SiC<inf>f</inf>/SiC presented a flexural strength of 470 MPa.