Influence of crystallinity on the corrosion rate of chemically vapor‐infiltrated SiCf/SiC composites under 310°C hydrothermal condition

• Published in: International journal of applied ceramic technology 2022-01, Vol.19 (1), p.258-267
• Main Authors: Han, Jangwon, Kim, Daejong, Lee, Hyeon‐Geun, Kim, Weon‐Ju, Park, Chan, Park, Ji Yeon
• Format: Article
• Language: English
• Subjects: Ceramic fiber reinforced ceramics; Columnar structure; Composite materials; composites; corrosion; Corrosion effects; Corrosion rate; Corrosion tests; Crystal structure; Crystallinity; Diffraction; Infiltration; Mathematical analysis; Raman spectroscopy; Silicon carbide; Weight loss
• ISSN: 1546-542X; 1744-7402
• DOI: 10.1111/ijac.13821

The rationale of this work was to investigate the effect of crystallinity on corrosion rate of chemically vapor‐infiltrated (CVI) SiCf/SiC composites. SiCf/SiC composites were fabricated from fabric preform with densifying by CVI. To evaluate the effect of crystallinity on the behavior of SiCf/SiC composite, the infiltration temperature was increased from 1000 to 1100°C with 25°C intervals. X‐ray diffraction and Raman spectroscopy results indicated the diffraction peaks, as the infiltration temperature elevated, become sharp and the transverse optical (TO) and longitudinal optical (LO) phonon peak of the composite increased, respectively. Hydrothermal corrosion tests were performed on the polished surface in a static autoclave at a DI water for 7 and 30 days to evaluate the relation of crystallinity and the microstructure of the composite. Low infiltration temperature revealed columnar growth structure at the matrix after corrosion while weight loss behavior had a linear decreasing tendency from 1000 to 1075°C. These findings are particularly important for determining the infiltration temperature which changes the crystallinity of the SiC phase, and hence the corrosion rate of SiCf/SiC composites.