Residual stress and interface debonding behavior in Si3N4w reinforced SiCN composites prepared by the PIP process: A case study

Abstract

Polymer infiltration and pyrolysis (PIP), as a preparation route for ceramic matrix composites, employs the polymer-to-ceramic transformation inside the preforms to gradually buildup the matrix. The effects of the structural transformation on the residual stress and on the interface debonding behavior of PIP derived Si3N4 whisker reinforced SiCN (Si3N4w/SiCN) composites are analyzed. Accordingly, the Si3N4w whisker in the composites are under residual compressive stress after the formation of the polymer-derived ceramic matrix. An increase in the pyrolysis heating rate from 1 to 10 ℃/min effectively lowers the residual stress from 195.8 to 91.3 MPa. Interface fracture energies of Si3N4w/SiCN derived from the debonding behavior significantly rise from <11.91 to 21.82 J/m2 with the annealing temperature from 900 to 1400 ℃. The residual stress and interfacial behavior are related to the in-situ densification/shrinkage and structural rearrangement during pyrolysis and annealing.