2D C/ SiC ZrB2 composites were fabricated by combining chemical vapor infiltration, slurry infiltration
and polymer infiltration and pyrolysis (PIP) process. Effects of PIP cycle number and heat treatment on the microstruc ture and mechanical properties of the C/ SiC ZrB2 were investigated. Two densification processes were compared: PIP
combining with CVI and by using CVI alone on porous C/ SiC infiltrated slurry. The results indicated that, at the same
heat treatment temperature, the times of heat treatment had little effect on the open porosity and flexural strength. The
flexural strength increased nonlinearly with increasing PIP cycles. After twice PIP processes, the flexural strength of the
composite increased, and reached its maximum value at the fifth PIP cycle. The open porosity and flexural strength of
the composite fabricated by 5 times PIP are 8. 0% and 423 MPa, respectively. After slurry infiltration, this hybrid
process of PIP and CVI is more suitable to densification of the composite than single CVI process.