Relationship between matrix porosity and flexural strength of short fiber reinforced all-oxide ceramic matrix composites

This study analyzes the influence of porosity on Nextel TM 610/Al 2 O 3 -ZrO 2 short-fiber-reinforced composites for the first time. Its goal was the comparison of a short-fiber-reinforced all-oxide ceramic matrix composite (SF-Ox/Ox) with a fabric-reinforced material. Since the matrix system and the processing were the same for both materials, differences can be related to the use of short-fibers instead of fabrics. Zirconium-n-butoxide was infiltrated to decrease the porosity from 32% to 46%, which increased the bending strength and the Young’s modulus from 85±19 MPa to 120±23 MPa and 40±10 GPa to 82±12 GPa, respectively. The strain decreased with decreasing porosity from 0.25±0.05% to 0.16±0.03%. The damage-tolerant behavior was maintained for all samples, which was never shown for SF-Ox/Ox in such a porosity range. The less anisotropic alignment of the short-fibers is therefore advantageous for crack-deflection. This offers the possibility to obtain damage-tolerance while having a denser matrix system.