EFFECT OF TEST TEMPERATURE ON THE CHARACTERIZATION OF MELT INFILTRATEDSiC/SiCCOMPOSITES

Abstract

The high temperature property of SiC/SiC composites fabricated by the melt infiltration (MI) process has been investigated. SiC/SiC composites reinforced with BN/SiC double coated Hi-Nicalon SiC fibers were fabricated by infiltrating molten silicon into a braiding fibric preform containing C and SiC particles. The mechanical properties of MI- SiC/SiC composites were carried out at the elevated temperatures using the three point bending test. The microstructure of MI- SiC/SiC composites was examined by means of SEM and EDS. The matrix region of MI- SiC/SiC composites represented the chemical fluctuation depending on the composition ratio of Si and C elements. The flexural strength of MI- SiC/SiC composites greatly decreased at the temperatures higher than 1100 °C, due to microstructural instabilities such as interfacial debonding and matrix oxidation.