Thermal Stability of Melt Infiltrated SiC/SiC Composites

Ceramic Matrix Composite Vane Subelement Burst Testing

“…The material has been well documented [6][7][8] and consists of Sylramic® SiC fibers with In-Situ BN interface [ 8 ] and a Chemical Vapor Infiltration (CVI), slurry cast and Melt Infiltrated matrix. Because analyses predicted the occurrence of significant interlaminar stresses at the trailing edge, a fabric was developed to provide reinforcement in the high stress region.…”

Modeling the Thermostructural Stability of Meltinfiltrated SiC/SiC Composites

“…In a companion paper [ 5 ] , stress-free thermal exposure studies were performed to evaluate the UTS retention of SiC/BN/SiC composites with Sylramic-iBN Sic fibers and silicon-containing MI Sic matrices. In this paper, a simple UTS degradation analytical model was developed based on fiber attack by silicon diffusion through CVI Sic coated tows.…”

“…Fabrication methods, test procedures, and UTS test results for the thermally exposed Sylramic-iBN fiber-reinforced MI SiC/BN/SiC-Si composites are presented in a companion paper [5]. In the as-fabricated condition, these 2D 0/90 composites displayed an average UTS value of -400 MPa with -37 total volume % fibers.…”

“…As a possible explanation for this last observation, it has recently been determined that Sic fibers can lose strength within MI SiC/BN/SiC-Si composites even under stressTfree high-temperature conditions [5]. This intrinsically controlled property loss is manifested by a reduction in the ultimate tensile strength (UTS) of composites after thermal exposure between 1300 and 1400°C for up to 500 hours in air.…”

“…1 and 2 and other UTS degradation results under different conditions [ 5 ] , three simplifying assumptions were made. First, the migration of elemental silicon into the tows occurs by thermally activated diffusion through the CVI Sic interphase overcoating.…”