Analysis of failure mechanisms of Oxide - Oxide ceramic matrix composites

The failure mechanisms of Oxide-Oxide ceramic matrix composites AS-N610 were studied at both room temperature and high temperature using tensile and fatigue tests with and without lateral and laminar notches. The unnotched coupons had an average tensile strength of 423 MPa with elastic modulus of 97 GPa at room temperature showing a perfect elastic behaviour whereas the laminar notched samples shown similar strength of 425 MPa with elastic modulus (98 GPa) revealing pseudo-ductile behaviour. A reduction in tensile strength of the oxide ceramic matrix composites was observed at high temperatures. Thermal shock experiments revealed that the retained strength of the samples quenched from 1100 degrees C deteriorated by similar to 10 % (395 +/- 15 MPa). In all samples, fracture origin was observed on the mid-plane showing a higher degree of fiber pull-out, delamination and pseudo ductile behaviour. Finite element analysis confirmed higher stress concentration on the areas of failures.

Automated summary

The failure mechanisms of Oxide-Oxide ceramic matrix composites AS-N610 were investigated in this study. The unnotched samples showed perfect elastic behavior at room temperature, while the notched samples exhibited pseudo-ductile behavior. The tensile strength of the composites decreased at high temperatures. Thermal shock experiments revealed a reduction in retained strength of the samples. Fracture origin was observed on the mid-plane of all samples, indicating higher fiber pull-out, delamination, and pseudo-ductile behavior. Finite element analysis confirmed stress concentration on the failure areas.