Optimization method for self-healing improver in fiber-reinforced ceramics using SiC healing agent

Abstract

An optimization method for lowering the effective self-healing temperature of fiber-reinforced self-healing ceramics (shFRC) was investigated using B₄C as a self-healing improver. B₄C was selected based on its ability to oxidize at lower temperatures than SiC, a typical self-healing agent. B₄C/SiC powder mixtures were studied for their high-temperature oxidation behavior, revealing reaction initiation around 600°C during constant heating rate. At 1000°C, B₄C oxidation accelerated SiC oxidation by 15 times. Several shFRCs with B₄C/ SiC interlayer were fabricated to investigate self-healing behavior. Results showed strength recovery after heat treatment at 650°C for 1 h with ≥6 vol% B₄C, and at 600°C for 1 h with ≥12 vol% B₄C. However, treatments above 700°C led to no strength recovery due to component degradation from oxide formation. The study concludes that optimizing self-healing improvers requires consideration of their stability prior to reaction, heat generation relative to the amount added, and characteristics of the produced oxide. In the case of B₄C, 12 vol% with maximized self-healing performance at 600°C is optimal. This research demonstrates the potential of B₄C in lowering the effective self-healing temperature of shFRCs, while emphasizing the importance of balancing improver content and treatment temperature to maintain the composite's integrity.