Microstructural and high-temperature cyclic oxidation response of NiCoCrAlY coatings with and without SiC + ZrB2 reactive-element dispenser

• Published in: Corrosion science Vol. 189; p. 109617
• Main Authors: Vásquez Hernández, Gabriel Israel, González Albarrán, Marco Aurelio, Rodríguez de Anda, Eduardo, Díaz Guillen, Juan Carlos, Jiménez Alemán, Omar, Portilla Zea, Karla Guadalupe, Olmos, Luis
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 15.08.2021; Elsevier BV
• Subjects: Aluminum oxide; Beta phase; Cycling oxidation; Diffusion layers; High temperature; Interfaces; Intermetallics; Mixed oxides; Oxidation; Refractory materials; Scale (corrosion); Silicon carbide; Silicon compounds; XRD; Zirconium compounds; Interfaces; Intermetallics; XRD; Cycling oxidation
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2021.109617

•The SiC-ZrB2 can be used as a reactive-element (Si) compound dispenser.•Silicon behaves as a reactive-element reducing the oxidation.•Coatings with 1 % SiC-ZrB2 displayed thinner TGO layers and a lower oxidation rate.•Silicon seems to promote the stabilization of α-Al2O3 at earlier stages of oxidation. In this study, the microstructural and cyclic-oxidation evolution behavior of bond coats (BC) containing SiC + ZrB2 dispersed particles were evaluated. The SiC + ZrB2 dispersed particles at the oxidation temperature of 1130 °C, dissolved at early stages, stabilizing the beta phase, diminishing the aluminum outward diffusion. The silicon at the BC/TC interface, or very close to it, behaved as a reactive element promoting the rapid formation and stabilization of α-Al2O3 (TGO), and a second scale layer of mixed oxides and silicon-rich compounds, jointly limiting inward oxygen diffusion and resulting in thinner TGO layers, whose kinetic oxidation follows a sub-parabolic behavior, increasing oxidation life-span.