Influence of the Active Particles on the Self-Healing Efficiency in Glassy Matrix

In the present paper, we present the influence of the composition of the active particles on the self-healing property in glass-particles (B, B(4)C, VB, V, or VC) composites. The thermogravimetric curves and oxidation kinetics at 700 degrees C of the active particles are reported. We show that the oxidation rate is higher with vanadium-based particles than with boron-base ones, mainly due to the formation of B(2)O(3) that acts as a diffusion barrier to oxygen. In situ healing of cracks in composites was observed using high-temperature environmental scanning electron microscopy (HT-ESEM). The composition of the phases formed by reaction between the oxidation products and the glassy matrix is systematically determined. Self-healing occurs as a consequence of oxidation of active particles, which leads to the formation of an oxide, such as V(2)O(5) and/or B(2)O(3) that is fluid enough to fill in the crack at high temperature. The crack healing is obtained whatever the nature of the active particle.