Characterization of self-healing glassy composites by high-temperature environmental scanning electron microscopy (HT-ESEM).

In situ high-temperature healing of cracks in composites made of glass and vanadium boride (VB) particles was observed using an environmental scanning electron microscope equipped with a high-temperature chamber (HT-ESEM). HT-ESEM is an adequate tool for studying the self-healing property of these materials. The change in crack length as a function of redox atmospheric conditions is reported. No self-healing behaviour was observed under reducing conditions, while a complete and rapid healing of the cracks was measured under oxidizing conditions. HT-ESEM image analyses enabled the monitoring of the healing effect. The self-healing mechanism was identified as a consequence of the VB active particles oxidation and subsequent pouring of fluid oxides into the cracks. These innovative composites offer an interesting potential in the domain of solid oxide fuel cell sealants.