The Effect of Amorphous Polysilazane and Infiltration Method on The Densification of SiCf/SiC Composites

Abstract

In this study, we investigated the ability of polysilazane as starting materials to fabricate SiCf/SiC composite prepared by slurry infiltration method, i.e., vacuum infiltration (VI) and electrophoretic infiltration (EPI). After infiltration, sintering was performed using hot pressing vacuum furnace at 1750 °C for 1 h in Ar atmosphere and applied pressure of 20 MPa. Phase analysis revealed the formation of a-SiC for EPI, while a-SiC and p-SiC were detected for VI. It seems the transformation of (3- to a-SiC enhances significantly in the EPI, resulting in single-phase a-SiC. Moreover, the presence of excess carbon after sintering indicated that the amount of Si and C was not stoichiometry. The density of SiCf/SiC composite infiltrated by VI and EPI was 2.68 and 2.92 g/cm3, respectively, corresponding to 81.6 and 90.9% of theoretical density. Although the density is quite different, the average flexural strength for VI and EPI was 174 ± 5 and 200 ± 7 MPa, respectively, which does not differ significantly. However, the tail extension was observed for both samples, indicates the toughness increase compared to monolithic ceramic. This study indicates that polysilazane can be used as an alternative precursor for the fabrication of SiCf/SiC composites using a slurry infiltration method.