Fabrication and characteristics of Hi-Nicalon SiC fiber reinforced RBSC filter with asymmetric structure

Abstract

Hi-Nicalon SiC fiber reinforced reaction bonded SiC (RBSC) filter was fabricated by Si melt infiltration method to use in the hot gas filter of IGCC (Intergrated Gasification Combined Cycle) system. The chopped Hi-Nicalon SiC fiber with 200~500 ㎛ in length were used for reinforcements in porous RBSC matrix. The pore size and porosity for SiC fiber reinforced RBSC was controlled by varying the amount of residual Si in porous RBSC matrix, the size of SiC particle, and SiC fiber fraction used. The pore size and porosity for fabricated SiC fiber reinforced RBSC filter support were about 80~100 ㎛ and 32~38 vol. %, respectively. The pore size of RBSC filtration layer was less than 10 ㎛. It was found that about small amounts (about 4~7 vol.%) of SiC fiber in RBSC matrix was good enough to improve the mechanical properties of RBSC filter. The flexural strengths of SiCf-RBSC filter were in the range of 35-66 MPa depending on the amounts of residual Si in RBSC matrix, which was maintained at 900oC. It was revealed that Hi-Nicalon SiCf reinforced RBSC filter fabricated in this study showed the partial delayed fracture behavior during bending tests.