This work investigated the behaviour of introducing ZrSi₂ layer between the top coat layer Yttria-stabilized zirconia (YSZ) and the bond coat layer CoNiCrAlY in thermal barrier coatings where ZrSi₂ layer helped self-healing of the cracks. Powder mixtures of ZrSi₂/8YSZ and ZrSi₂ /CoNiCrAlY were used to imitate the real case. At 800 °C under argon, there was no change in the chemical composition of both ZrSi₂ and 8YSZ. ZrSi₂ was oxidized in case of treatment in air atmosphere at 800 °C with no evidence for any self-healing reactions. At 1000 and 1200 °C under argon the formation of ZrSiO₄ phase was detected which was a strong evidence of self-healing reaction. ZrSiO₄ phase was also detected at 1200 °C in air with the appearance of SiO₂ phase. A limited interaction was detected at 1000 °C between ZrSi₂ and CoNiCrAlY under vacuum. Si was detected in the surface of CoNiCrAlY grains and Ni was detected in the composition of ZrSi₂. This behavior could contribute to a chemical bonding between ZrSi₂ and CoNiCrAlY layers. The obtained data were confirmed by XRD, SEM and EDX analyses.

Keywords: Self-healing, zirconium silicide, thermal barrier coatings