Cyclic-Dependent Damage Evolution in Self-Healing Woven SiC/[Si-B-C] Ceramic-Matrix Composites at Elevated...

Area of Science:

• Materials Science
• Ceramic Matrix Composites (CMCs)
• Mechanical Engineering

Background:

• Self-healing ceramic matrix composites (CMCs) offer enhanced durability in high-temperature applications.
• Understanding cycle-dependent damage evolution is critical for predicting the service life of CMCs.
• Previous research has not fully elucidated the interplay of environmental and loading factors on damage progression in these specific CMC systems.

Purpose of the Study:

• To investigate the cycle-dependent damage evolution in self-healing Hi-Nicalon™ SiC/[Si-B-C] and Hi-Nicalon™ SiC/[SiC-B₄C] ceramic matrix composites.
• To establish relationships between damage parameters and fatigue mechanisms at 600 °C and 1200 °C.
• To predict the fatigue behavior of these CMCs under varying conditions.

Main Methods:

• Experimental investigation of damage parameters including internal friction, dissipated energy, Kachanov's damage parameter, and broken fiber fraction.
• Testing of 2.5D woven Hi-Nicalon™ SiC/[Si-B-C] and 2D woven Hi-Nicalon™ SiC/[SiC-B₄C] composites at 600 °C and 1200 °C.
• Analysis of damage evolution under different temperatures, peak stresses, and loading frequencies.

Main Results:

• For Hi-Nicalon™ SiC/[Si-B-C], temperature is a key factor; internal friction behavior differs significantly between 600 °C and 1200 °C, with lower interface shear stress at 1200 °C.
• For Hi-Nicalon™ SiC/[SiC-B₄C] at 1200 °C, loading frequency governs fatigue; lower frequencies (0.1 Hz) lead to higher interface shear stress degradation rates.
• The study established predictive models for fatigue damage development based on experimental data.

Conclusions:

• Cycle-dependent damage evolution in self-healing CMCs is sensitive to temperature, testing environment, peak stress, and loading frequency.
• Temperature critically influences the fatigue of Hi-Nicalon™ SiC/[Si-B-C] composites, affecting internal friction and interface shear stress.
• Loading frequency is a dominant factor in the fatigue of Hi-Nicalon™ SiC/[SiC-B₄C] composites at high temperatures.