Combination of PIP and LSI processes for SiC/SiC ceramic matrix composites

Silicon carbide fiber-reinforced silicon carbide matrix composites (SiC/SiC CMCs) are promising candidates for hot gas components in jet engines. Three common manufacturing routes are chemical vapor infiltration, reactive melt infiltration (RMI) and polymer infiltration and pyrolysis (PIP). A combination of the processes seems attractive: the remaining porosity after PIP process can be closed by subsequent siliconization, resulting in a dense material. This work describes a new approach of a combined PIP and RMI process. SiC/SiC CMCs were manufactured by PIP process using Hi-Nicalon Type S fibers. An additional RMI was carried out after a reduced number of PIP cycles. Microstructure was examined via mu CT, SEM and EDS. Bending strength was determined to 433 MPa; strain to failure was 0.60%. The overall processing time was reduced by 55% compared to standard PIP route. The hybrid material contained 70% less unreacted carbon than material produced by LSI process alone.